DE102020008033B4 - Method for transmitting an ultrasonic burst with a distance-dependent number of instantaneous ultrasonic frequencies - Google Patents

Abstract

Method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps
- Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS);
- Step 2: Receiving an ultrasonic burst reflected by an object (O);
- Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst;
- Step 4: Repeating steps 1 to 4, wherein the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2), characterized in that
- that the number of ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) and the associated number of frequency curves (SF1, SF2, SF3) of these ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic burst (UB) depends on the distance (D).

Description

Field of invention

The invention relates to a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles.

General introduction

Autonomous driving requires increasingly sophisticated measurement devices to assess the vehicle's surroundings. The bandwidth of the ultrasonic signals that can be transmitted and received is significantly limited, as the ultrasonic transducers used exhibit a strong resonance with high Q and thus a narrow bandwidth.

An optimization of the modulation frequency curve within a chirp signal is therefore necessary.

In this context, we would like to point out the WO 2010 / 063 510 A1 The WO 2010 / 063 510 A1 describes a detection device and a method for detecting the surroundings of a vehicle. WO 2010 / 063 510 A1 uses such signals, which are particularly interesting in connection with the use of ultrasound in vehicles.

From the EP 1 231 481A2 A method for operating an ultrasonic multi-sensor array is known that does not address the bandwidth problem.

From the US 7 693 007 B2 An ultrasonic sensor with a separate ultrasonic transmitter and ultrasonic receiver is known.

From the WO 2010 / 063 510 A1 A detection device is known, in particular for detecting the surroundings of a vehicle. WO 2010 / 063 510 A1 This does not address the bandwidth issue.

From the DE 10 2008 002 232 A1 A method and device for determining the distance and/or speed of an object relative to a vehicle is known. DE 10 2008 002 232 A1 This does not address the bandwidth issue.

From the DE 101 45 292 A1 A method for measuring distance using ultrasound is known. DE 101 45 292 A1 This does not address the bandwidth issue.

From the JP S58-50 484 A A guidance device for reversing a motor vehicle using ultrasound is known. JP S58-50 484 A This does not address the bandwidth issue.

None of the presented writings solves the bandwidth problem or contributes to such a solution.

Task

The proposal is therefore based on the task of creating a solution which does not have the above-mentioned disadvantages of the prior art and has further advantages.

This problem is solved by a proposal according to the claims. More precisely, its solution is supported by the proposal according to the claims. Further refinements are the subject of the subclaims.

Solution to the task

1. 1. Schritt 1: Aussenden eines Ultraschallbursts mit einer Ultraschallburstdauer (bd), die eine maximale Ultraschallburstdauer (bd) nicht überschreitet, durch ein Ultraschallsensorsystem (USS);
2. 2. Schritt 2: Empfangen eines durch ein Objekt (O) reflektierten Ultraschallbursts;
3. 3. Schritt 3: Bestimmen des Abstands (D) zwischen dem Ultraschallsensorsystem (USS) und dem Objekt (O) in Abhängigkeit von dem empfangenen reflektierten Ultraschallburst;
4. 4. Schritt 4: Wiederholen der Schritte 1 bis 4, wobei die Ultraschallburstdauer (bd) von dem ermittelten Abstand (D, s1, s2) abhängt.

The invention relates to a method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles. The method comprises the following steps:

1. 1. Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS);
2. 2. Step 2: Receiving an ultrasonic burst reflected by an object (O);
3. 3. Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) depending on the received reflected ultrasonic burst;
4. 4. Step 4: Repeat steps 1 to 4, whereby the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2).

The method is characterized in that the number of ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) and the associated number of frequency curves (SF1, SF2, SF3) of these ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic burst (UB) depends on the distance (D).

One method for adapting the ultrasonic signals, more precisely the ultrasonic bursts (UB) to the object to be examined in the environment of a vehicle is the adaptation of the transmission amplitude and the transmission frequency when detecting an object depending on the object properties, as in for example, distance and/or reflectivity. For this purpose, the received amplitude is recorded by an ultrasonic measuring device, the ultrasonic sensor system (USS), using appropriate ultrasonic receivers and/or ultrasonic transducers (US1, US2, US3) and compared with a target received amplitude curve. If the received amplitude is too high at a particular time, the ultrasonic transducers are dampened individually or jointly. The dampening of one or more ultrasonic transducers is preferably achieved by connecting damping elements, for example, by connecting resistors in parallel to the ultrasonic transducers (US1, US2, US3). If the amplitude is too low, the relevant ultrasonic transducer is supplied with more vibration energy.

Another method is the control of the ultrasonic burst amplitude (A) with which the ultrasonic transducer (US1, US2, IS3) transmits. This involves attempting to keep the received amplitude of the echoes constant when received by the ultrasonic transducer (US1, US2, US3) at the location of the respective ultrasonic transducer or at the location of the ultrasonic sensor system (USS), which comprises multiple ultrasonic transducers (USS). A central idea of this disclosure is the adaptation of ultrasonic burst properties to the previously detected environment. It is ultimately irrelevant whether detection was carried out using ultrasound or other methods such as radar and/or lidar and/or image analysis of camera images. Such an adaptation of an ultrasonic burst property for transmitted ultrasonic bursts can, for example, be an increase and/or decrease in the ultrasonic burst amplitude when transmitting the ultrasonic burst depending on the distance of an object to be examined or detected. In a similar manner, the instantaneous frequency of the ultrasonic burst can also be increased or decreased during the transmission of the ultrasonic burst depending on the distance of the object. A substantially hyperbolic curve of the instantaneous frequency of the ultrasonic burst as a function of time within an ultrasonic burst is particularly preferred for improved Doppler robustness.

For the detection of a small object, for example, the size of a moth, a sound pressure of 130 dB with a 10 ms ultrasonic burst duration and a 110 ms time interval between two consecutive ultrasonic bursts is typically appropriate at a distance of 15 m. High sound pressure, low frequency, long pulse duration, and low pulse repetition rate are important.

• • exakte 3D-Lokalisierung
• • Strukturerfassung (Objektklassifizierung, Größe, sensitive Objektkomponenten (z.B. bestimmte zu schützende Körperteile eines Menschen))
• • Kompensation des Dopplereffekts

When approaching an object in the vehicle environment that has been identified as important, the tasks

• • exact 3D localization
• • Structure detection (object classification, size, sensitive object components (e.g. certain body parts of a person to be protected))
• • Compensation of the Doppler effect

• • Kurz mit hoher Wiederholrate (80 bis 90 Ultraschallbursts /Sekunde bei Annäherung),
• • bis zu 200 Ultraschallbursts /Sekunde in der Nähe des Objekts,
• • Breitbandige Aussendung und Empfang der Ultraschallbursts, um mehr spektrale Information zu erhalten,
• • Lineare oder hyperbolisch abwärts weisende Frequenzmodulation der Ultraschallbursts,
• • Reduktion der Ultraschallburstamplitude in der Nähe des Objekts, was Übersteuerungen verhindert.

Ultrasound bursts in this phase:

• • Short with high repetition rate (80 to 90 ultrasonic bursts / second when approaching),
• • up to 200 ultrasonic bursts per second near the object,
• • Broadband transmission and reception of ultrasonic bursts to obtain more spectral information,
• • Linear or hyperbolic downward frequency modulation of the ultrasonic bursts,
• • Reduction of the ultrasonic burst amplitude near the object, which prevents overloading.

During the approach phase to the object or a group of objects, the sequence and shape of the ultrasonic bursts are preferably continuously varied during the approach: At greater distances, the ultrasonic bursts are preferably loud, with a large ultrasonic burst amplitude and a relatively low-frequency instantaneous ultrasonic frequency, and preferably narrowband. Frequency-modulated chirps with a higher starting frequency and a quieter, i.e., smaller, ultrasonic burst amplitude are preferably used near the object or objects. For good processing, very fast signal processing for high pulse repetition frequencies is advisable.

A 3D localization option for objects may be achieved using multiple ultrasound transducers that are appropriately positioned relative to one another. If the ultrasound transducers are very broadband, two sensors can be placed next to each other at "ear's distance." This paper proposes increasing the broadband capability by coupling multiple ultrasound transducers to form an ultrasound sensor system. Direction can be determined, in particular, using time-of-flight differences. The evaluation of such time-of-flight differences can be performed using a neural network. The relationship between the height of the reflecting object and the frequency content of the echo can also be evaluated using a neural network. The method, which will be further developed below, involves two ultrasonic transducers placed close together. One of these two ultrasonic transducers should be equipped with a low resonant frequency, and the other of the two ultrasonic transducers should be equipped with a high resonant frequency, which are activated at different distances from the object to emit the ultrasonic bursts.

1. a. Abstandsfehler: Überschätzung der Entfernung zum Objekt,
2. b. Genauigkeitsfehler: Das Objekt kann nicht mehr so präzise lokalisiert werden (Aufweitung der CCF-Kurve)

A vehicle moving towards an object must compensate for two Doppler errors:

1. a. Distance error: overestimation of the distance to the object,
2. b. Accuracy error: The object can no longer be located as precisely (widening of the CCF curve)

1. 1. Beide Fehler werden verringert, wenn bei gleichbleibender Ultraschallburstdauer die Bandbreite erhöht wird, oder bei gleichbleibender Bandbreite, die Ultraschallburstdauer reduziert wird.
2. 2. Da das Fahrzeug sich in der Regel auf das interessierende Objekt zubewegt führt dies zu einer Unterschätzung des Abstands auf Basis von Laufzeitbestimmungen. Dies kann die Überschätzung durch den Dopplereffekt bei einer bestimmten Distanz zum Objekt kompensieren. Der Ultraschallburst wird daher vorschlagsgemäß laufend entsprechend angepasst, damit der kompensierte Abstand dem realen Abstand entspricht. Bevorzugt wird hierfür ein neuronales Netz verwendet. Dieses neuronale Netz regelt bevorzugt auf Basis eines oder mehrerer empfangener Ultraschalsignale oder auf Basis von aus den empfangenen Ultraschallsignalen abgeleiteten Signalen einen oder mehrere Ultraschallburstparameter eines oder mehrerer zeitlich nachfolgender Ultraschallbursts.
3. 3. Eine vollständige Kompensation des Genauigkeitsfehlers erfolgt nur bei einer streng hyperbolischen Frequenzmodulation der Ultraschallburstmomentanfrequenz während des Ultraschallbursts in Abhängigkeit von der Zeit (t).

Grundsätzlich ist also eine kurze Ultraschallburstdauer bei hoher Bandbreite erstrebenswert, um ein Maximum an Informationen zu erhalten. Durch Training eines neuronalen Netzes für die Anpassung der Ultraschallbursteigenschaften der in Zukunft zu sendenden Ultraschallbursts kann dieses neuronale Netz für die Bestimmung und Einstellung dieser Ultraschallbursteigenschaften vor der Aussendung eines Ultraschallbursts genutzt werden. Ziel ist dabei die optimale Ultraschallburstanpassung für variablen kompensierenden Abstand.Compensation is necessary for this:

1. 1. Both errors are reduced if the bandwidth is increased while maintaining the same ultrasonic burst duration, or if the ultrasonic burst duration is reduced while maintaining the same bandwidth.
2. 2. Since the vehicle is typically moving toward the object of interest, this leads to an underestimation of the distance based on time-of-flight determinations. This can compensate for the overestimation due to the Doppler effect at a certain distance from the object. Therefore, the proposed approach proposes continuously adjusting the ultrasonic burst so that the compensated distance corresponds to the actual distance. A neural network is preferably used for this purpose. This neural network preferably controls one or more ultrasonic burst parameters of one or more subsequent ultrasonic bursts based on one or more received ultrasonic signals or on signals derived from the received ultrasonic signals.
3. 3. A complete compensation of the accuracy error occurs only with a strictly hyperbolic frequency modulation of the ultrasonic burst instantaneous frequency during the ultrasonic burst as a function of time (t).

In principle, a short ultrasonic burst duration with a high bandwidth is desirable to obtain maximum information. By training a neural network to adapt the ultrasonic burst characteristics of future ultrasonic bursts, this neural network can be used to determine and adjust these ultrasonic burst characteristics before an ultrasonic burst is transmitted. The goal is optimal ultrasonic burst adaptation for variable compensating distances.

For structural detection and/or object classification, it is useful to evaluate the fine structure of the echoes of the ultrasonic bursts. This takes advantage of the fact that each part of an object, such as a pedestrian, reflects the ultrasonic burst at slightly different times. The resulting temporal fine structure of the echo can then be used to create a "depth profile" of the object. At the same time, spectral differences also arise due to the different reflection/absorption behavior of different materials on the object's various surfaces.

As with 3D localization, differences between the received signals from multiple ultrasonic sensor systems with multiple ultrasonic transducers are evaluated. The environment of the ultrasonic sensor system, such as the type of mounting or the structure of the surfaces surrounding the ultrasonic sensor system, and other components, typically add further frequency filtering, for which the neural network used for evaluation must be trained.

Another method relates to a method for transmitting an ultrasonic signal using an ultrasonic sensor system (USS). The ultrasonic signal has an ultrasonic burst (UB), wherein the ultrasonic burst has at least two, but typically considerably more, ultrasonic pulses (P ₀ to P ₇ ). Each of the at least two ultrasonic pulses (P ₀ to P ₇ ) has a temporal ultrasonic pulse start and a temporal ultrasonic pulse end. In this case, for example, the intersection point of the burst-like fluctuating sound pressure during the ultrasonic burst with the 50% sound pressure amplitude based on the maximum sound pressure occurring during an ultrasonic pulse can be used to determine the ultrasonic pulse start and the ultrasonic pulse end. The ultrasonic period (T ₁ to T ₇ ) of an individual ultrasonic pulse (P ₀ to P ₇ ) in the sense of this document is the time from the temporal ultrasonic pulse end of the immediately preceding ultrasonic pulse to the temporal ultrasonic pulse end of the respective ultrasonic pulse. These definitions are chosen in order to be able to determine an instantaneous ultrasonic frequency (f _m ) in the time of the ultrasonic pulse. In the broadest sense, an ultrasonic pulse within the meaning of this document is a wavelet whose stretching factor can be varied during the duration of the ultrasonic pulse. In this respect, any type of time-limited wavelet with a time-limited wavelet duration is therefore encompassed by the term ultrasonic pulse within the meaning of this document. The wavelet duration corresponds to the ultrasonic pulse duration (dh) of the ultrasonic period (T ₁ to T ₇ ). The respective ultrasonic The instantaneous sound frequency (f _m1 to f _m7 ) is the inverse of the respective ultrasonic period (T ₁ to T ₇ ) of the respective ultrasonic pulse (P ₀ to P ₇ ). The rate of change (v _f ) of the instantaneous ultrasonic frequency (f _m ) is thus the first derivative of the instantaneous ultrasonic frequency (f _m ) with respect to time (t). The ultrasonic burst (UB) begins at an ultrasonic burst start (UBS) that is the same as the ultrasonic pulse start of the first pulse (P ₀ ) of the ultrasonic burst (UB). The ultrasonic burst (UB) ends at an ultrasonic burst end (UBE) that is the same as the ultrasonic pulse end of the last pulse (P ₇ ) of the ultrasonic burst (UB). The ultrasonic burst (UB) has a burst duration (BD) that is the value of the time difference between the ultrasonic burst start (UBS) and the ultrasonic burst end (UBE). In this disclosure, it is now proposed that the ultrasonic burst (UB) can be divided in time into a first burst phase (t _1a ) and a second burst phase (t _1b ) by a first half-frequency time point (t _1/50% ). The first half-frequency time point (t _1/50% ) is the time within the transmission time of an ultrasonic burst (UB) at which the instantaneous ultrasonic frequency (f _m ) corresponds to the first upper half-maximum amplitude frequency (f _1o ) or the first lower half-maximum amplitude frequency (f _1u ). At the first upper half-maximum amplitude frequency (f _1o ), the amplitude (A) of the sound radiation from the first ultrasonic transducer (US1) is half the first amplitude maximum (A _max1 ) of the sound radiation from the first ultrasonic transducer (US1) at its first resonance frequency (f ₁ ). The first upper half-maximum amplitude frequency (f _1o ) of the first ultrasonic transducer (US1) is above the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1). At the first lower half-maximum amplitude frequency (f _1u ), the amplitude (A) of the sound radiation from the first ultrasonic transducer (US1) is also half the first amplitude maximum (A _max1 ) of the sound radiation from the first ultrasonic transducer (US1) at its first resonance frequency (f ₁ ). The first lower half-maximum amplitude frequency (f _1u ) of the first ultrasonic transducer (US1) is below the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1).

This method is characterized in that the amount of the average rate of change (v _f ) of the instantaneous ultrasonic frequency (f _m ) in the first burst phase (t _1a ) differs from the amount of the average rate of change (v _f ) of the instantaneous ultrasonic frequency (f _m ) in the second burst phase (t _1b ) preferably by more than 10% and/or better by more than 20% and/or better by more than 50% and/or better by more than 100%.

Preferably, the first burst phase (t _1a ) has a temporal length that differs from the temporal length of the second burst phase (t _1b ) by more than 10% and/or by more than 20% by more than 50% by more than 100%.

Likewise preferably, the time length of the first burst phase (t _1a ) is more than 10% and/or more than 20%, more than 50%, more than 75% shorter than the time length of the second burst phase (t _1b ).

According to the proposal, this method can be carried out at several instantaneous ultrasonic frequencies (f _m1 , f _m2 ) simultaneously, which provides additional information about objects that may be located in the vicinity of the vehicle. This then involves a method for emitting an ultrasonic signal, wherein the ultrasonic signal has an overall ultrasonic burst (UB) and wherein the overall ultrasonic burst (UB) comprises a first ultrasonic partial burst and wherein the overall ultrasonic burst (UB) comprises a second ultrasonic partial burst. Each ultrasonic partial burst of the ultrasonic partial bursts has at least two, typically considerably more, ultrasonic pulses (P ₀ to P ₇ ). Each of the at least two ultrasonic pulses (P ₀ to P ₇ ) of an ultrasonic partial burst again has a temporal ultrasonic pulse start and a temporal ultrasonic pulse end. The ultrasonic period (T ₁ to T ₇ ) of an individual ultrasonic pulse (P ₀ to P ₇ ) of an ultrasonic subburst, hereinafter referred to as the respective ultrasonic pulse, is again the time from the temporal ultrasonic pulse end of the ultrasonic pulse immediately preceding the respective ultrasonic pulse to the temporal ultrasonic pulse end of the respective ultrasonic pulse. The first instantaneous ultrasonic frequency (f _1m ) of the first ultrasonic subburst is the reciprocal of the instantaneous ultrasonic period (T _1m ) of the first ultrasonic subburst. The second instantaneous ultrasonic frequency (f _2m ) of the second ultrasonic subburst is the reciprocal of the instantaneous ultrasonic period (T _2m ) of the second ultrasonic subburst. The first ultrasonic subburst begins at a first start time (t _1s ), which is the same as the ultrasonic pulse start of the first ultrasonic pulse (P ₀ ) of the first ultrasonic subburst. The first ultrasonic subburst ends at a first end time (t _1e ), which is equal to the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the first ultrasonic subburst. The first ultrasonic subburst has a first ultrasonic subburst duration (t _1e -t _1s ), which is the value of the time difference between the first end time (t _1e ) minus the first start time (t _1s ). The second ultrasonic subburst begins at a second start time (t _2s ), which is equal to the start of the ultrasonic pulse of the first ultrasonic pulse (P ₀ ) of the second ultrasonic subburst. The second ultrasonic subburst ends at a second end time (t _2e ), which is equal to the ultrasonic pulse end of the last ultrasonic pulse (P7) of the second ultrasonic subburst. The second ultrasonic subburst has a second ultrasonic subburst duration (t _2e -t _2s ), which is the value of the time difference between the second end time (t _2e ) minus the second start time (t _2s ). This method variant is characterized in that the first instantaneous ultrasonic frequency (f _1m ) is different from the second instantaneous ultrasonic frequency (f _2m ) at least at one point in time between the first start time (t _1s ) and the first end time (t _1e ) and simultaneously between the second start time (t _2s ) and the second end time (t _2e ). Thus, two instantaneous ultrasonic frequencies (fm1, fm2) are always emitted by the ultrasonic sensor system (USS).

A first method variant provides that the second start time (t _2s ) lies between the first start time (t _1s ) and the first end time (t _1e ) and/or that the second start time (t _2s ) is equal to the first start time (t _1s ).

In another variant, the second end time (t _2e ) is between the first start time (t _1s ) and the first end time (t _1e ) and/or the second end time (t _2e ) is equal to the first end time (t _1e ).

In some applications it may be useful for the first instantaneous ultrasonic frequency (f _1m ) at the first end time (f _1e ) to be equal to the second instantaneous ultrasonic frequency (f _2m ) at the second end time (f _2e ).

In other applications, it may be useful if the first instantaneous ultrasonic frequency (f _1m ) at the first start time (f _1s ) is equal to the second instantaneous ultrasonic frequency (f _2m ) at the second start time (f _2s ).

In other applications, it may be useful if the first instantaneous ultrasonic frequency (f _1m ) at the first start time (f _1s ) is different from the second instantaneous ultrasonic frequency (f _2m ) at the second start time (f _2s ).

And in yet other applications it may be useful if the first instantaneous ultrasonic frequency (f _1m ) at the first end time (f _1e ) is different from the second instantaneous ultrasonic frequency (f _2m ) at the second end time (f _2e ).

1. a. des Erzeugens des ersten Ultraschallteilbursts mit einem ersten Ultraschall-Transducer (UBS1) und/oder
2. b. des Erzeugens des zweiten Ultraschallteilbursts mit einem zweiten Ultraschall-Transducer (UBS2), der vom ersten Ultraschall-Transducer (UBS1) verschieden ist.

A method for transmitting an ultrasonic signal developed from the above methods comprises the steps

1. a. generating the first ultrasonic subburst with a first ultrasonic transducer (UBS1) and/or
2. b. generating the second ultrasonic subburst with a second ultrasonic transducer (UBS2) which is different from the first ultrasonic transducer (UBS1).

Preferably, the first ultrasonic transducer (US1) has a first resonance frequency (f ₁ ) and the second ultrasonic transducer (US2) has a second resonance frequency (f ₂ ), wherein the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) is different from the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2). This allows additional information to be used for object classification of the objects (O).

1. a. die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o) minus des Betrags der zweiten unteren Halbmaximalamplitudenfrequenz (f_2m) bevorzugt größer ist als die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o) minus des Betrags der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u) und /oder
2. b. die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o) minus des Betrags der der zweiten unteren Halbmaximalamplitudenfrequenz (f_2m) bevorzugt größer ist als die Differenz des Betrags der zweiten oberen Halbmaximalamplitudenfrequenz (f_2o) minus des Betrags der der zweiten unteren Halbmaximalamplitudenfrequenz (f_2m) oder
3. c. die Differenz des Betrags der zweiten oberen Halbmaximalamplitudenfrequenz (f_2o) minus des Betrags der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u) bevorzugt größer ist als die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o) minus des Betrags der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u) und /oder
4. d. die Differenz des Betrags der zweiten oberen Halbmaximalamplitudenfrequenz (f_2o) minus des Betrags der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u) bevorzugt größer ist als die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o) minus des Betrags der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u).

The first ultrasonic transducer (US1) preferably has a first bandwidth (Δf ₁ ) with a first upper half-maximum amplitude frequency (f _1o ) and a first lower half-maximum amplitude frequency (f _1u ). The second ultrasonic transducer (US1) preferably has a second bandwidth (Δf ₂ ) with a second upper half-maximum amplitude frequency (f _2o ) and a second lower half-maximum amplitude frequency (f _2m ). The first bandwidth (Δf ₁ ) and the second bandwidth (Δf ₂ ) overlap in the frequency range. This has the advantage that a frequency sweep can be carried out over a larger frequency range. It is therefore preferred that

1. a. the difference between the magnitude of the first upper half-maximum amplitude frequency (f _1o ) minus the magnitude of the second lower half-maximum amplitude frequency (f _2m ) is preferably greater than the difference between the magnitude of the first upper half-maximum amplitude frequency (f _1o ) minus the magnitude of the first lower half-maximum amplitude frequency (f _1u ) and/or
2. b. the difference between the magnitude of the first upper half-maximum amplitude frequency (f _1o ) minus the magnitude of the second lower half-maximum amplitude frequency (f _2m ) is preferably greater than the difference between the magnitude of the second upper half-maximum amplitude frequency (f _2o ) minus the magnitude of the second lower half-maximum amplitude frequency (f _2m ) or
3. c. the difference between the magnitude of the second upper half-maximum amplitude frequency (f _2o ) minus the magnitude of the first lower half-maximum amplitude frequency (f _1u ) is preferably greater than the difference between the magnitude of the first upper half-maximum amplitude frequency (f _1o ) minus the magnitude of the first lower half-maximum amplitude frequency (f _1u ) and/or
4. d. the difference between the magnitude of the second upper half-maximum amplitude frequency (f _2o ) minus the magnitude of the first lower half-maximum amplitude frequency (f _1u ) is preferably greater is the difference between the magnitude of the first upper half-maximum amplitude frequency (f _1o ) minus the magnitude of the first lower half-maximum amplitude frequency (f _1u ).

Furthermore, it is advantageous if the angle-dependent first energy density of the first sound emission of the first ultrasonic transducer (US1) differs from the angle-dependent second energy density of the second sound emission of the second ultrasonic transducer (US2) and/or the angle-dependent first sound amplitude of the first sound emission of the first ultrasonic transducer (US1) differs from the angle-dependent second sound amplitude of the second sound emission of the second ultrasonic transducer (US2). As explained in the figures, this allows information about the angular range and the distance of an object (O1, O2) to be obtained from the reflection signal.

In addition to the methods for transmitting ultrasonic bursts described so far, there are also analogous methods for receiving the ultrasonic bursts.

1. a. des Empfangs des reflektierten Ultraschallsignals mit einem ersten Ultraschall-Transducer (US1) als erstes Ultraschallempfangssignal, wobei der erste Ultraschall-Transducer eine erste Resonanzfrequenz (f1) aufweist, und
2. b. des Empfangs des reflektierten Ultraschallsignals mit einem zweiten Ultraschall-Transducer (US2) als zweites Ultraschallempfangssignal, wobei der zweite Ultraschall-Transducer (US2) eine zweite Resonanzfrequenz (f2) aufweist, und
3. c. des Verarbeitens des ersten Ultraschallempfangssignals und des zweiten Ultraschallempfangssignals und
4. d. des Schließens auf Abstände von Objekten (O1, O2), die das Ultraschallsignal reflektiert haben, zu dem gemeinsamen Ultraschallsystem (USS) und
5. e. des Schließens auf einen Winkel zwischen der Sichtlinie von dem gemeinsamen Ultraschallsystem (USS) zu Objekten (O1, O2), die das Ultraschallsignal reflektiert haben, einerseits und der Ultraschallsystemachse (USA) des gemeinsamen Ultraschallsystems (USS) andererseits oder Schließen auf einen Winkelbereich in dem sich die Objekte (O1, O2) jeweils befinden.

The ultrasonic signal that is now received, which was typically previously reflected by an object, was preferably generated using one of the previously described methods. The complex structure of the ultrasonic signals is discussed in more detail in the figure descriptions. Therefore, it is recommended to briefly glance over the figures with the frequency curves in order to understand which type of ultrasonic bursts are to be received. A first ultrasonic transducer (US1) and a second ultrasonic transducer (US2) are to be part of a common ultrasonic sensor system (USS). The ultrasonic sensor system (USS) is to have an ultrasonic system axis (USA). The method for receiving the complex ultrasonic bursts comprises the steps

1. a. receiving the reflected ultrasonic signal with a first ultrasonic transducer (US1) as the first ultrasonic reception signal, wherein the first ultrasonic transducer has a first resonance frequency (f1), and
2. b. receiving the reflected ultrasonic signal with a second ultrasonic transducer (US2) as a second ultrasonic reception signal, wherein the second ultrasonic transducer (US2) has a second resonance frequency (f2), and
3. c. processing the first ultrasonic reception signal and the second ultrasonic reception signal and
4. d. inferring distances from objects (O1, O2) that have reflected the ultrasonic signal to the common ultrasonic system (USS) and
5. e. inferring an angle between the line of sight from the common ultrasound system (USS) to objects (O1, O2) that have reflected the ultrasound signal, on the one hand, and the ultrasound system axis (USA) of the common ultrasound system (USS) on the other hand, or inferring an angular range in which the objects (O1, O2) are respectively located.

From what has been described so far, a method for determining an object position results, the implementation of a method with the aid of the different sound cones of the different ultrasound transducers (US1-US2, US3) with the aid of a first common ultrasound system (USS1) to determine a first distance (s1) and a first angle or first angular range, and the analogous implementation of this method with the aid of a preferably, but not necessarily identical, second common ultrasound system (USS2), which is different from the first common ultrasound system (USS1) - i.e. not identical to it - and spaced apart, to determine a second distance (s2) and a second angle or a second distance and second angular range. According to this method, a spatial coordinate or a spatial region in which an object (O) is located that has reflected the ultrasound signal is then determined based on the first distance (s1) and the second distance (s2), as well as the determined first angular range and the determined second angular range. The information corresponding to the first angular range and the first distance (s1) corresponds to a first spatial region approximately in the shape of a first torus at the first distance from the first ultrasonic sensor system (USS1). The information corresponding to the second angular range and the second distance (s1) corresponds to a second spatial region approximately in the shape of a second torus at the second distance from the second ultrasonic sensor system (USS2). The intersection of the spatial points located within both the first spatial region and the second spatial region results in a reduced, further spatial region in which the object in question should be located.

• - Schritt 1: Aussenden eines Ultraschallbursts mit einer Ultraschallburstdauer (bd), die eine maximale Ultraschallburstdauer (bd) nicht überschreitet, durch ein Ultraschallsensorsystem (USS);
• - Schritt 2: Empfangen eines durch ein Objekt (O) reflektierten Ultraschallbursts;
• - Schritt 3: Bestimmen des Abstands (D) zwischen dem Ultraschallsensorsystem (USS) und dem Objekt (O) in Abhängigkeit von dem empfangenen reflektierten Ultraschallburst;
• - Schritt 4: Wiederholen der Schritte 1 bis 4, wobei die Ultraschallburstdauer (bd) von dem ermittelten Abstand (D, s1, s2) abhängt.

Furthermore, another method for transmitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles is disclosed, comprising the following steps:

• - Step 1: Emission of an ultrasonic burst with an ultrasonic burst duration (bd) not exceeding a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS);
• - Step 2: Receiving an ultrasonic burst reflected by an object (O);
• - Step 3: Determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst;
• - Step 4: Repeat steps 1 to 4, whereby the ultrasonic burst duration (bd) depends on the determined distance (D, s1, s2).

It has been shown that it is advantageous if the ultrasonic burst length of the ultrasonic burst duration (bd) is multiplied by the fourth root of the determined distance (D) according to the formula $$\text{bd}={\text{bd}}_{\text{1}}*{\text{D}}^{-1/4}+{\text{bd}}_{\text{0}}{\text{ mit bd}}_{\text{0}}{\text{ und bd}}_{\text{1}}\text{ als Konstanten}$$ is extended in time, i.e. its magnitude is increased. This has the advantage that the total energy that returns to the emitting ultrasound transducer upon reflection allows conclusions to be drawn about the object, since this amount of energy no longer depends on the distance, but only on the size and reflectivity of the object. It is sufficient if such ultrasound pulses, corrected for the burst length (bd), are emitted from time to time. For example, if several objects have been located at different distances, it may be useful to emit an ultrasound burst (UB) for each detected object, optimized for the distance of this object.

• - Schritt 1: Aussenden eines Ultraschallbursts mit einer Ultraschallbursteigenschaft durch ein Ultraschallsensorsystem (USS);
• - Schritt 2: Empfangen eines durch ein Objekt (O) reflektierten Ultraschallbursts;
• - Schritt 3: Bestimmen und Bewerten einer Eigenschaft des Objekts (O) in Abhängigkeit von dem empfangenen reflektierten Ultraschallburst und/oder ggf. mehreren empfangenen reflektierten Ultraschallbursts;
• - Schritt 4: Wiederholen der Schritte 1 bis 4, wobei zumindest eine Ultraschallbursteigenschaft eines nachfolgend ausgesendeten Ultraschallbursts von der Bewertung der ermittelten Eigenschaft abhängt.

This then results in a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps:

• - Step 1: Emitting an ultrasonic burst having an ultrasonic burst characteristic by an ultrasonic sensor system (USS);
• - Step 2: Receiving an ultrasonic burst reflected by an object (O);
• - Step 3: Determining and evaluating a property of the object (O) as a function of the received reflected ultrasonic burst and/or possibly several received reflected ultrasonic bursts;
• - Step 4: Repeating steps 1 to 4, wherein at least one ultrasonic burst property of a subsequently emitted ultrasonic burst depends on the evaluation of the determined property.

It is important that one of the subsequently transmitted ultrasonic bursts does not have to follow immediately on the previous ultrasonic burst. Rather, it is conceivable to transmit further ultrasonic bursts with different measuring tasks between these two ultrasonic bursts. Such sequences of ultrasonic bursts can be mixed. Thus, the ultrasonic burst property of an ultrasonic burst to be transmitted can depend on one or more objects in the vicinity of the ultrasonic sensor system (USS) or the environment of the ultrasonic sensor system (USS). Thus, the ultrasonic burst property of an ultrasonic burst to be transmitted can depend on one or more objects in the vicinity of a vehicle or the environment of the vehicle if such an ultrasonic sensor system (USS) is installed in the vehicle. Several ultrasonic burst properties are described below, which can also affect the properties of several ultrasonic bursts.

• - Schritt 1: Aussenden eines ersten Ultraschallbursts mit einer Ultraschallbursteigenschaft mit einem ersten Ultraschallbursteigenschaftswert durch ein Ultraschallsensorsystem (USS);
• - Schritt 2: Empfangen eines durch ein erstes Objekt (O) reflektierten ersten Ultraschallbursts;
• - Schritt 3: Bestimmen und Bewerten einer ersten Eigenschaft des ersten Objekts (O1) in Abhängigkeit von dem empfangenen reflektierten ersten Ultraschallburst und/oder ggf. mehreren empfangenen reflektierten ersten Ultraschallbursts;
• - Schritt 4: Aussenden eines zweiten Ultraschallbursts mit der Ultraschallbursteigenschaft mit einem zweiten Ultraschallbursteigenschaftswert durch das Ultraschallsensorsystem (USS);
• - Schritt 5: Empfangen eines durch ein zweites Objekt (O) reflektierten zweiten Ultraschallbursts;
• - Schritt 6: Bestimmen und Bewerten einer zweiten Eigenschaft des zweiten Objekts (O2) in Abhängigkeit von dem empfangenen reflektierten zweiten Ultraschallburst und/oder ggf. mehreren empfangenen reflektierten zweiten Ultraschallbursts;
• - Schritt 7: Wiederholen der Schritte 1 bis 6,
  • ▪ wobei zumindest die erste Ultraschallbursteigenschaft eines nachfolgend ausgesendeten ersten Ultraschallbursts von der Bewertung der ermittelten ersten Eigenschaft abhängt und
  • • wobei zumindest die zweite Ultraschallbursteigenschaft eines nachfolgend ausgesendeten zweiten Ultraschallbursts von der Bewertung der ermittelten zweiten Eigenschaft abhängt.

This may then result, for example, in a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, which comprises the following steps:

• - Step 1: Emitting a first ultrasonic burst having an ultrasonic burst characteristic with a first ultrasonic burst characteristic value by an ultrasonic sensor system (USS);
• - Step 2: Receiving a first ultrasonic burst reflected by a first object (O);
• - Step 3: Determining and evaluating a first property of the first object (O1) as a function of the received reflected first ultrasonic burst and/or possibly a plurality of received reflected first ultrasonic bursts;
• - Step 4: Emission of a second ultrasonic burst with the ultrasonic burst property with a second ultrasonic burst property value by the ultrasonic sensor system (USS);
• - Step 5: Receiving a second ultrasonic burst reflected by a second object (O);
• - Step 6: Determining and evaluating a second property of the second object (O2) as a function of the received reflected second ultrasonic burst and/or possibly a plurality of received reflected second ultrasonic bursts;
• - Step 7: Repeat steps 1 to 6,
  • ▪ wherein at least the first ultrasonic burst property of a subsequently emitted first ultrasonic burst depends on the evaluation of the determined first property and
  • • wherein at least the second ultrasonic burst property of a subsequently emitted second ultrasonic burst depends on the evaluation of the determined second property.

It's important to note that additional ultrasonic bursts can also be inserted for other purposes. The first ultrasonic bursts can also be emitted more or less frequently than the second ultrasonic bursts.

Just as the ultrasonic burst duration (bd) can be optimized depending on the object, the ultrasonic burst amplitude can also be optimized depending on the object. It can be useful if the amplitude (A) of at least three ultrasonic bursts emitted in immediate or non-immediate temporal succession is essentially proportional to (D+D ₀ ) ^1/k , with 2≤k≤5 or preferably k=2 or k=4, and depends on the determined distance (A), where D ₀ is a constant that can be zero. In this case, additional ultrasonic bursts (UB) can be emitted between these ultrasonic bursts (UB) to measure other objects and environmental properties.

Typically, several ultrasonic bursts (UB) are emitted at a temporal ultrasonic burst interval, wherein the first temporal ultrasonic burst interval is the temporal interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst, and wherein the second temporal ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the third ultrasonic burst immediately following this second ultrasonic burst depends on the determined distance (D) of an object (O, O, O2).

Another possible variation of an ultrasonic burst property is a variation of the temporal ultrasonic burst spacing of the ultrasonic bursts. The temporal ultrasonic burst spacing of the ultrasonic bursts can, for example, become shorter with decreasing spatial distance (D) between the ultrasonic sensor system and the object (O). Preferably, when the spatial distance (D) between the ultrasonic sensor system and the object (O) is shortened by a length I, the temporal ultrasonic burst spacing of the ultrasonic bursts is shortened by a time 2*I/c, where c is the speed of sound, with a tolerance of +/- 25% and/or better with a tolerance of +/- 10% and/or better with a tolerance of +/- 5%.

As a further variation possibility of an ultrasonic burst property, the number of ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) and the associated number of frequency curves (SF1, SF2, SF3) of these ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic burst (UB) can depend on the distance (D).

• • eine Single-Mode-Zeit (smt₁, smt₂, smt₃, smt1, smt2) und/oder
• • eine Dual-Mode-Zeit (dmt₁₂, dmt₂₃, dmt1, dmt2) und/oder
• • eine Tri-Mode-Zeit (t_mt, tmt₁₂₃, tmt₁₁₂).

A further modification of an ultrasonic burst property may be that an ultrasonic burst has at least two of the following time period types:

• • a single-mode time (smt ₁ , smt ₂ , smt ₃ , smt1, smt2) and/or
• • a dual-mode time (dmt ₁₂ , dmt ₂₃ , dmt1, dmt2) and/or
• • a tri-mode time (t _mt , tmt ₁₂₃ , tmt ₁₁₂ ).

This ultrasonic burst property can also depend on objects in the surroundings or the environment in part or as a whole. Such ultrasonic sensor systems are preferably used in vehicles. In this case, it is preferably an ultrasonic sensor system (USS) for a vehicle, with a first ultrasonic transducer (US1) and a second ultrasonic transducer (US2). Of course, the ultrasonic sensor system can also have more than two ultrasonic transducers (US1, US2, US3). In our example, the first ultrasonic transducer (US1) has a first resonant frequency (f ₁ ) and the second ultrasonic transducer (US2) has a second resonant frequency (f ₂ ), wherein the first resonant frequency (f ₁ ) is different from the second resonant frequency (f ₂ ).

Preferably, the first ultrasonic transducer (US1) has a first bandwidth (Δf ₁ ) and the second ultrasonic transducer (US2) has a second bandwidth (Δf ₂ ). To ensure that a chirp can be performed across the full bandwidth without significant amplitude drops, it is advantageous for the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) and the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) to overlap.

Preferably, the ultrasonic sensor system (USS) is designed such that the ultrasonic sensor system (USS) can emit an ultrasonic burst (UB) with an instantaneous ultrasonic burst frequency (f _m ) dependent on time (t), which cannot be emitted by an ultrasonic transducer of the ultrasonic transducers (US1, US2) of the ultrasonic sensor system (USS) at at least one point in time during the emission of the ultrasonic burst (UB). This thus describes an increase in the bandwidth compared to a single ultrasonic transducer with regard to emission.

In analogy, the ultrasonic sensor system (USS) is preferably designed so that the ultrasonic sensor system (USS) generates an ultrasonic burst (UB) with an instantaneous ultrasonic burst frequency (f _m ) dependent on time (t), which cannot be received by an ultrasonic transducer of the ultrasonic transducers (US1, US2) of the ultrasonic sensor system (USS) at least at one point in time during the emission of the ultrasonic burst (UB). This thus describes an increase in bandwidth compared to a single ultrasonic transducer with regard to reception.

Preferably, the ultrasonic sensor system (USS) can emit an ultrasonic burst (UB) having more than one ultrasonic burst instantaneous frequency (f _m1 , f _m2 , f _m3 ) in its spectrum, wherein each of the ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) during such an ultrasonic burst lies substantially within the bandwidth (Δf ₁ , Af ₂ , Af ₃ ) of at least one of the ultrasonic transducers (US1, US2, US3). This is also an ultrasonic burst property that can depend on the examination target, typically an object (O, O1, O2) in the environment of the ultrasonic sensor system or the vehicle. Conversely, the ultrasonic sensor system (USS) can then typically receive an ultrasonic burst (UB) which has more than one ultrasonic burst instantaneous frequency (f _m1 , f _m2 , f _m3 ) in its spectrum, wherein each of the ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) during such an ultrasonic burst lies substantially within the bandwidth (Δf ₁ , Af ₂ , Af ₃ ) of at least one of the ultrasonic transducers (US1, US2, US3). Preferably, the output signals of the ultrasonic transducers are then combined to form an ultrasonic reception signal. In the simplest case, this can be done, for example, by summing the output signals of the ultrasonic transducers.

An ultrasonic sensor system (USS) is also conceivable in which the ultrasonic sensor system (USS) can receive an ultrasonic burst (UB) which has more than one ultrasonic burst instantaneous frequency (f _m1 , f _m2 , f _m3 ) in its spectrum at least at one time during the burst duration (bd),
wherein each of the ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) during such an ultrasonic burst lies substantially in the bandwidth (Δf ₁ , Af ₂ , Af ₃ ) of at least one of the ultrasonic transducers (US1, US2, US3) and wherein at least one of these ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) during such an ultrasonic burst is not in the bandwidth (Δf ₁ , Af ₂ , Af ₃ ) of at least one of the ultrasonic transducers (US1, US2, US3) at at least one point in time. The use of multiple ultrasonic transducers therefore results in an increase in the bandwidth with regard to reception.

In one possible configuration, multiple ultrasonic transducers (US1, US2) of an ultrasonic sensor system (USS) are driven by a common control signal (AS). This has the advantage that such an ultrasonic sensor system (USS) essentially behaves like a single ultrasonic transducer for control circuits.

Similarly, a common ultrasonic reception signal can be generated from the output signals of the ultrasonic transducers (US1, US2), which can also have several sub-signals.

Such an ultrasonic sensor system (USS) can be designed such that the sound radiation lobe of the first ultrasonic transducer (US1) has a first vertical opening angle (α _V ) and the sound radiation lobe of the second ultrasonic transducer (US2) has a second vertical opening angle (β _V ) or such that the receiving lobe of the first ultrasonic transducer (US1) has a first vertical opening angle (α _V ) and the receiving lobe of the second ultrasonic transducer (US2) has a second vertical opening angle (β _V ). In this case, the first vertical opening angle (α _V ) should be different from the second vertical opening angle (β _V ) so that a reflected ultrasonic signal has different frequencies which encode the angular range in which the reflecting object may be located around the axis (USA) of the ultrasonic sensor system (USS).

In an analogous manner, the sound radiation lobe of the first ultrasonic transducer (US1) has a first horizontal opening angle (α _H ) and the sound radiation lobe of the second ultrasonic transducer (US2) has a second vertical opening angle (β _V ), or the reception lobe of the first ultrasonic transducer (US1) has a first horizontal opening angle (α _H ) and the reception lobe of the second ultrasonic transducer (US2) has a second vertical opening angle (β _V ). Here, too, the first horizontal opening angle (α _H ) is preferably different from the second vertical opening angle (β _V ), which results in an analogous advantage.

Most preferably, the proposed ultrasonic sensor system comprises further ultrasonic transducers in addition to the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2), resulting in an ultrasonic transducer array in which the ultrasonic transducers (US1, US2, US3) have different resonance frequencies (f ₁ , f ₂ , f ₃ ). In the simplest case, the proposed ultrasonic sensor system comprises further ultrasonic transducers (US1) and the second ultrasonic transducer (US2) also has a third ultrasonic transducer (US3), wherein the third ultrasonic transducer (US3) has a third resonance frequency (f ₃ ), which is preferably different from the second resonance frequency (f ₂ ) and from the first resonance frequency (f ₁ ).

In this case, with three ultrasonic transducers (US1, US2, US3), the ultrasonic transducers (US1, US2, US3) are preferably arranged in an isosceles triangle. The edge lengths of this isosceles triangle are preferably less than ten times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and/or better still, less than five times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and/or better still, less than three times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and/or better still, less than twice the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3).

• • Empfangen des Ultraschallgesamtbursts (UB), mittels eines Ultraschallsensorsystems (USS) mit zumindest einem ersten Ultraschall-Transducer (US1) und einem zweiten UltraschallTransducer (US2), wobei der erste Ultraschall-Transducer (US1) eine erste Resonanzfrequenz (f₁) und eine erste Bandbreite (Δf₁) aufweist und wobei der zweite Ultraschall-Transducer (US2) eine zweite Resonanzfrequenz (f₂) und eine zweite Bandbreite (Δf₂) aufweist und wobei die erste Resonanzfrequenz (f₁) von der zweiten Resonanzfrequenz (f₂) verschieden ist und wobei die erste Bandbreite (Δf₁) die zweite Bandbreite (Δf₂) überlappt und wobei der erste Ultraschalltransducer (US1) ein erstes Ultraschallempfangsteilsignal erzeugt und wobei der zweite Ultraschalltransducer (US2) ein zweites Ultraschallempfangsteilsignal erzeugt;
• • Erzeugen eines Ultraschallempfangssignals aus dem ersten Ultraschallempfangsteilsignal und dem zweiten Ultraschallempfangsteilsignal, wobei das Ultraschallempfangssignal mehrere Teilempfangssignale umfassen kann und wobei ein oder mehrere Teilempfangssignale mit Ultraschallempfangsteilsignalen übereinstimmen können;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals.

In an analogous manner, a method for receiving an ultrasonic signal results, wherein the ultrasonic signal comprises an overall ultrasonic burst (UB) which comprises a first ultrasonic partial burst and a second ultrasonic partial burst. Here, too, each ultrasonic partial burst of the ultrasonic partial bursts comprises at least two ultrasonic pulses (P ₀ to P ₇ ), of which each of the at least two ultrasonic pulses (P ₀ to P ₇ ) of an ultrasonic partial burst has a temporal ultrasonic pulse start and a temporal ultrasonic pulse end. As before, the ultrasonic period (T ₁ to T ₇ ) of an individual ultrasonic pulse (P ₀ to P ₇ ) of an ultrasonic partial burst, hereinafter referred to as the respective ultrasonic pulse, is the time from the temporal ultrasonic pulse end of the ultrasonic pulse immediately preceding the respective ultrasonic pulse to the temporal ultrasonic pulse end of the respective ultrasonic pulse. The first instantaneous ultrasonic frequency (f _1m ) of the first ultrasonic sub-burst is again the inverse of the instantaneous ultrasonic period (T _1m ) of the first ultrasonic sub-burst and the second instantaneous ultrasonic frequency (f _2m ) of the second ultrasonic sub-burst is again the inverse of the instantaneous ultrasonic period (T _2m ) of the second ultrasonic sub-burst. The first ultrasonic sub-burst begins at a first start time (t _1s ), which is the same as the start of the ultrasonic pulse of the first ultrasonic pulse (P ₀ ) of the first ultrasonic sub-burst. The first ultrasonic sub-burst ends at a first end time (t _1e ), which is the same as the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the first ultrasonic sub-burst. The first ultrasonic sub-burst has a first ultrasonic sub-burst duration (t _1e -t _1s ) which corresponds to the value of the time difference between the first end time (t _1e ) minus the first start time (t _1s ). The second ultrasonic sub-burst begins at a second start time (t _2s ), which is the same as the start of the ultrasonic pulse of the first ultrasonic pulse (P ₀ ) of the second ultrasonic sub-burst. The second ultrasonic sub-burst ends at a second end time (t _2e ), which is the same as the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the second ultrasonic sub-burst. The second ultrasonic sub-burst has a second ultrasonic sub-burst duration (bd = t _2e - t _2s ), which corresponds to the value of the time difference between the second end time (t _2e ) minus the second start time (t _2s ). The first instantaneous ultrasonic frequency (f _1m ) is preferably different from the second instantaneous ultrasonic frequency (f _2m ) at least at one time between the first start time (t _1s ) and the first end time (t _1e ) and simultaneously between the second start time (t _2s ) and the second end time (t _2e ). The reception procedure then includes the following steps:

• • Receiving the total ultrasound burst (UB) by means of an ultrasound sensor system (USS) with at least a first ultrasound transducer (US1) and a second ultrasound transducer (US2), wherein the first ultrasound transducer (US1) has a first resonance frequency (f ₁ ) and a first bandwidth (Δf ₁ ) and wherein the second ultrasound transducer (US2) has a second resonance frequency (f ₂ ) and a second bandwidth (Δf ₂ ) and wherein the first resonance frequency (f ₁ ) is different from the second resonance frequency (f ₂ ) and wherein the first bandwidth (Δf ₁ ) overlaps the second bandwidth (Δf ₂ ) and wherein the first ultrasound transducer (US1) generates a first ultrasound reception sub-signal and wherein the second ultrasound transducer (US2) generates a second ultrasound reception sub-signal;
• • Generating an ultrasonic reception signal from the first ultrasonic reception sub-signal and the second ultrasonic reception sub-signal, wherein the ultrasonic reception signal may comprise a plurality of sub-reception signals and wherein one or more sub-reception signals may correspond to ultrasonic reception sub-signals;
• • Determining environmental information based on the ultrasonic reception signal.

Typically, at least one time during the burst duration (bd) of the total ultrasound burst, the first instantaneous ultrasound frequency (f _1m ) is not within the first bandwidth (Δf ₁ ) of the first ultrasound transducer (US1), but within the second bandwidth (Δf ₂ ) of the second ultrasound transducer (US2), and/or the first instantaneous ultrasound frequency (f _1m ) is not within the second bandwidth (Δf ₂ ) of the second ultrasound transducer (US2), but within the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1), the second ultrasonic instantaneous frequency (f _2m ) not within the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) but within the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2), and/or the second ultrasonic instantaneous frequency (f _2m ) not within the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) but within the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1).

A refinement of the method may include the step of inferring a distance to an object (O1, O2) and an angular range in which this object (O1, O2) is located based on differences between the first ultrasonic reception sub-signal and the second ultrasonic reception sub-signal or based on differences in signals derived therefrom. In particular, neural networks or other pattern recognition methods may be used for this purpose.

• • eine Single-Mode-Zeit (smt₁, smt₂, smt₃, smt1, smt2) und/oder
• • eine Dual-Mode-Zeit (dmt₁₂, dmt₂₃, dmt1, dmt2) und/oder
• • eine Tri-Mode-Zeit (t_mt, tmt₁₂₃, tmt₁₁₂)

The method for receiving an ultrasonic total burst may be characterized in that a received ultrasonic total burst has at least two of the following time period types:

• • a single-mode time (smt ₁ , smt ₂ , smt ₃ , smt1, smt2) and/or
• • a dual-mode time (dmt ₁₂ , dmt ₂₃ , dmt1, dmt2) and/or
• • a tri-mode time (t _mt , tmt ₁₂₃ , tmt ₁₁₂ )

• • Empfang des Ultraschallgesamtbursts und Erzeugung des besagten Ultraschallempfangssignals, das mehrere Teilempfangssignale umfassen kann;
• • Feststellen der ersten Zeitabschnittsart zu einem ersten Zeitpunkt innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals in Abhängigkeit von der festgestellten ersten Zeitabschnittsart.

Under these conditions, the procedure may include, among other steps:

• • Receiving the total ultrasound burst and generating said ultrasound reception signal, which may comprise a plurality of partial reception signals;
• • Determining the first time period type at a first time within the burst duration (bd) of the total ultrasound burst;
• • Determining environmental information based on the ultrasonic reception signal depending on the first time period type detected.

• • Feststellen der zweiten Zeitabschnittsart zu einem zweiten Zeitpunkt innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts, der vom ersten Zeitpunkt verschieden ist;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals in Abhängigkeit von der festgestellten ersten Zeitabschnittsart innerhalb eines ersten Zeitabschnitts innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals in Abhängigkeit von der festgestellten zweiten Zeitabschnittsart innerhalb eines zweiten Zeitabschnitts innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts,

This procedure can be refined by including the following steps:

• • Determining the second time period type at a second time within the burst duration (bd) of the total ultrasound burst, which is different from the first time;
• • Determining environmental information on the basis of the ultrasound reception signal depending on the determined first time period type within a first time period within the burst duration (bd) of the total ultrasound burst;
• • Determining environmental information on the basis of the ultrasound reception signal depending on the detected second time period type within a second time period within the burst duration (bd) of the total ultrasound burst,

The first and second time periods should preferably not overlap. At the very least, they should not completely overlap.

This document has always referred to ultrasound transducers. It is obvious to a person skilled in the art that, with regard to the transmission of the total ultrasound bursts, ultrasound transmitters can also be used which are only used and/or suitable for transmitting the total ultrasound bursts. It is also obvious to a person skilled in the art that, with regard to the reception of the total ultrasound bursts, ultrasound receivers can also be used which are only used and/or suitable for receiving the total ultrasound bursts. In this respect, the claims with regard to reception also include combinations of ultrasound transducers with one or more pure ultrasound receivers using the term "ultrasound transducer", and with regard to the transmission of total ultrasound bursts, the claims with regard to the term "ultrasound transducer" also include combinations of ultrasound transducers with one or more pure ultrasound transmitters using the term "ultrasound transducer".

In extreme cases, these may only be pure ultrasonic receivers or pure ultrasonic transmitters.

For example, it is conceivable to combine one or a few ultrasonic transducers used for transmitting and receiving with a larger number of pure ultrasonic receivers. The pure ultrasonic receivers can be manufactured inexpensively using MEMS, while the ultrasonic transmitters, in the form of ultrasonic transducers, can be constructed using piezo-based vibrating ceramics.

On this basis, an ultrasonic sensor system (USS), in particular for a vehicle or a robot or another mobile machine, can then be defined, which has a first, typically smaller number of ultrasonic transmitters and/or ultrasonic transducers, each having a piezoceramic as a sound-generating transmitting element, and which comprises a second number of pure ultrasonic receivers. Preferably, at least one of these ultrasound receivers is a MEMS-based ultrasound receiver. Most preferably, the number of pure MEMS ultrasound receivers is particularly high. Preferably, at least some of the ultrasound transmitters and/or ultrasound transducers and/or ultrasound receivers form an ultrasound system, as described above.

Advantage

Such an ultrasonic sensor system (USS) enables, at least in some implementations, the transmission and/or reception of more complex ultrasonic bursts than those possible with individual ultrasonic transducers and/or transmitters. This is particularly important in the context of creating environment maps and point clouds for autonomous driving. However, the advantages are not limited to this.

List of characters

• 1a as part of the 1 shows the course of the ultrasound burst amplitude (A) as a function of the burst duration (bd).
• 1b as part of the 1 shows a suggested burst duration depending on the object distance (D) to the nearest object.
• 1c as part of the 1 shows the ultrasonic burst amplitude (A) as a function of the object distance (D).
• 2a shows a simplified schematic of the temporal signal curve of a single, selected exemplary ultrasonic burst (UB).
• 2b shows the corresponding time course of the ultrasonic burst instantaneous frequency (f _m ) plotted against time (t) over the burst duration (bd).
• 2c 2c shows an exemplary course of the frequency change rate (v _f ) of the ultrasonic burst instantaneous frequency (f _m ) over the time (t) of the burst duration (bd).
• 3 shows an exemplary first spectral ultrasonic burst amplitude (A1) of a first ultrasonic transducer (US1) for the amplitude (A) of the sound radiation of this ultrasonic transducer (US1) when excited with a first excitation signal with the first excitation frequency (f _A1 ).
• 4 shows an exemplary second spectral ultrasonic burst amplitude (A2) for the amplitude (A) of the sound radiation of a second ultrasonic transducer (US2) when excited with a second excitation signal (AS2) with the second excitation frequency (f _A2 ).
• 5 5 shows an exemplary third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the sound radiation of a third ultrasonic transducer (US3) when excited with a transmission signal of the third excitation frequency (fA3).
• 6 6 shows, as an example, the superposition of a first, second and third amplitude spectrum in two extreme configurations.
• 7 to 10 show basically possible types of a frequency sweep.
• 11 shows an exemplary arrangement consisting of a first ultrasonic transducer (US1) and a second ultrasonic transducer (US2) and a third ultrasonic transducer (US3).
• 12 corresponds to the 7 with the difference that now a frequency sweep is generated using three ultrasonic sensors (US1, US2, US3).
• 13 shows a simplified and schematic example of a system for generating the exemplary frequency response of the 12 .
• 14 corresponds in essential parts to the 12 , whereby the excitation signal (AS) now temporarily comprises more than one excitation frequency (fA).
• 15 shows a simplified and schematic example of a system for generating the exemplary frequency response of the following 16 .
• 16 corresponds to the 12 with the difference that now a first frequency response (SF1), a second frequency response (SF2) and a third frequency response (SF3) are used together to generate an ultrasonic burst (UB).
• 17 corresponds to the 16 with the difference that now all frequency curves (SF1, SF2, SF3) end at a common end frequency (f _e ) as the respective instantaneous ultrasonic frequency (f _m1 , f _m2 , f _m3 ) at a common end time (t _e ).
• 18 and 19 The sound radiation of an ultrasonic sensor system (USS) with different resonance frequencies and aperture angles.
• 20 illustrates how the different types of modulation described above can now be used when approaching an important object (O), for example an obstacle.
• 21 illustrates the situation when using two ultrasonic sensor systems (USS1, USS2)
• 22 shows the course of the instantaneous ultrasound frequencies and their effect on the Doppler strength.

Description of the characters

Figure 1

1 shows in 1a the course of the ultrasonic burst amplitude (A) as a function of the burst duration (bd) (see also 2 ). As the ultrasonic burst lengthens, i.e., the burst duration (bd) increases, the ultrasonic burst amplitude (A) decreases.

1b shows a suggested burst duration as a function of the object distance (D) to the nearest object. The burst duration is not only increased with increasing object distance (D). Preferably, the ultrasonic burst length of the ultrasonic burst duration (BD) increases with the square root or the fourth root of the object distance (D). This increases the latency. However, the increase in the signal reflected by the object is carried out in such a way that the reduction in received amplitude of 1/D ⁴ is improved to a reduction of 1/D ^2. Even more preferably, the ultrasonic burst length of the ultrasonic burst duration (bd) is increased with the fourth root of the distance according to the formula bd = bd ₁ * D ^-1/4 + bd ₀ with bd ₀ and bd ₁ as constants. As a result, the total signal amplitude remains constant after reception and correlation in a correlator for the object to be measured.

To avoid overloading in the near field, not only is the burst duration (bd) reduced near the object, but preferably the ultrasonic burst amplitude is also reduced near the object. This allows the reception amplitude to be kept constant after reception and correlation, even when shortening the burst duration (bd) is no longer appropriate. Therefore, it is proposed here to adjust the burst duration of the ultrasonic bursts and the ultrasonic burst amplitude (A) so that the reception amplitude of the observed object remains constant or follows a predetermined sensitivity curve. 1c shows the ultrasonic burst amplitude (A) as a function of the object distance (D).

Figure 2

2a shows a simplified schematic of the temporal signal curve of a single, exemplary ultrasonic burst (UB). The ultrasonic burst (UB) begins at the time of the ultrasonic burst start (UBS). The ultrasonic burst (UB) ends at the time of the ultrasonic burst end (UBE). The time between the ultrasonic burst start (UBS) and the ultrasonic burst end (UBE) is the burst duration (BD). The ultrasonic burst (UB) has an ultrasonic burst amplitude (A), which can be understood here as the average amplitude of the ultrasonic burst (UB) over the burst duration (BD) of the respective ultrasonic burst (UB).

In the example of 2a The ultrasonic burst (UB) shown there has eight ultrasonic periods, each with one ultrasonic pulse, i.e., in this case, eight ultrasonic pulses (P ₀ to P ₇ ), for example. The zeroth ultrasonic pulse (P ₀ ) is assigned to the zeroth ultrasonic period, which is only half present. The ultrasonic periods (P ₀ to P ₇ ) of the ultrasonic burst (UB) have eight ultrasonic period durations (T ₀ to T ₇ ). The zeroth ultrasonic period duration (T ₀ ) is defined in this document as twice the temporal pulse width of the zeroth ultrasonic pulse (P ₀ ). The instantaneous ultrasonic frequency (f _jm ) of the jth ultrasonic pulse (P _j ) of the jth ultrasonic period is understood in this document to be the reciprocal of the jth ultrasonic period duration (T _j ) of the jth ultrasonic period. $$f_{\text{j}}=\frac{1}{T_{\text{j}}}$$

In 2b The corresponding temporal progression of the ultrasonic burst instantaneous frequency (f _m ) is plotted against time (t) over the burst duration (bd) as a sketch and example. In the example of the 2b The instantaneous frequency of the ultrasonic burst (f _m ) increases rapidly due to the beginning of the ultrasonic burst (UB) at the time of the ultrasonic burst start (UBS). In the example of the 2a the ultrasonic burst instantaneous frequency (f _m ) is then preferably continuously reduced, at least temporarily, following a hyperbola until the ultrasonic burst end (UBE).

2c shows an example of a curve of the rate of change of frequency (v _f ) of the instantaneous frequency of an ultrasonic burst (f _m ) over time (t) of the burst duration (bd). Initially, the frequency increases with a large positive rate of change of frequency (v _f ) as a result of the ultrasonic burst start (UBS) of 0 Hz. In this example, the rate of change of frequency (v _f ) is then briefly strongly negative and then increases linearly. The absolute value of the rate of change of frequency (v _f ) decreases linearly in this example.

Figure 3

3 is used here to explain basic terminology for understanding terms used in this document. 3 shows an exemplary first spectral ultrasonic burst amplitude (A1) of a first ultrasonic transducer (US1) for the amplitude (A) of the sound radiation of this ultrasonic transducer (US1) upon excitation with a first excitation signal having the first excitation frequency (f _A1 ). The exemplary first spectral ultrasonic burst amplitude (A1) has a first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) at a first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1). The exemplary first ultrasonic transducer (US1) has, in the example of 3 a first bandwidth (Δf ₁ ) of the first spectral ultrasonic burst amplitude (A1) for the amplitude (A) of the sound radiation of a first ultrasonic transducer (US1). In this document, this first bandwidth (Δf ₁ ) of a first spectral ultrasonic burst amplitude (A1) for the amplitude (A) of the first sound emission of a first ultrasonic transducer (US1) is defined here such that this first bandwidth (Δf ₁ ) of the first ultrasonic sensor (US1) is the first upper half-maximum amplitude frequency (f _1o ), at which the amplitude (A) of the sound emission of the first ultrasonic transducer (US1) is half of the first amplitude maximum (A _max1 ) of the sound emission of the first ultrasonic transducer (US1) at its first resonance frequency (f ₁ ), minus the first lower half-maximum amplitude frequency (f _1u ), at which the amplitude (A) of the sound emission of the first ultrasonic transducer (US1) is also half of the first amplitude maximum (A _max1 ) of the sound emission of the first ultrasonic transducer (US1) at its first resonance frequency (f ₁ ).

Figure 4

4 is used here to explain basic terminology for understanding terms used in this document. 4 shows an exemplary second spectral ultrasonic burst amplitude (A2) for the amplitude (A) of the sound radiation of a second ultrasonic transducer (US2) upon excitation with a second excitation signal (AS2) having the second excitation frequency (f _A2 ). The exemplary second spectral ultrasonic burst amplitude (A2) has a second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) at a second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2). The exemplary second ultrasonic transducer (US2) has, in the example of 4 a second bandwidth (Δf ₂ ) of the second spectral ultrasonic burst amplitude (A2) for the amplitude (A) of the sound radiation of a second ultrasonic transducer (US2). In this document, this second bandwidth (Δf ₂ ) of a second amplitude spectrum (A2) for the amplitude (A) of the second sound emission of a second ultrasonic transducer (US2) is defined here such that this second bandwidth (Δf ₂ ) of the second ultrasonic sensor (US2) is the second upper half-maximum amplitude frequency (f _2o ), at which the amplitude (A) of the sound emission of the second ultrasonic transducer (US2) is half of the second amplitude maximum (A _max2 ) of the sound emission of the second ultrasonic transducer (US2) at its second resonance frequency (f ₂ ), minus the second lower half-maximum amplitude frequency (f _2u ), at which the amplitude (A) of the sound emission of the second ultrasonic transducer (US2) is also half of the second amplitude maximum (A _max2 ) of the sound emission of the second ultrasonic transducer (US2) at its second resonance frequency (f ₂ ).

Figure 5

5 is also used here to explain basic terminology for understanding terms used in this document. 5 shows an exemplary third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the sound radiation of a third ultrasonic transducer (US3) when excited with a transmission signal of the third excitation frequency (f _A3 ). The exemplary third spectral ultrasonic burst amplitude (A3) has a third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) at a third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3). The exemplary third ultrasonic transducer (US3) has, in the example of 5 a third bandwidth (Δf ₃ ) of the third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the sound radiation of a third ultrasonic transducer (US3). In this document, this third bandwidth (Δf ₃ ) of a third spectral ultrasonic burst amplitude (A3) for the amplitude (A) of the third sound emission of a third ultrasonic transducer (US3) is defined here such that this third bandwidth (Δf ₃ ) of the third ultrasonic sensor (US3) is the third upper half-maximum amplitude frequency (f _3o ), at which the amplitude (A) of the sound emission of the third ultrasonic transducer (US3) is half of the third amplitude maximum (A _max3 ) of the sound emission of the third ultrasonic transducer (US3) at its third resonance frequency (f ₃ ), minus the third lower half-maximum amplitude frequency (f _3u ), at which the amplitude (A) of the sound emission of the third ultrasonic transducer (US3) is also half of the third amplitude maximum (A _max3 ) of the sound emission of the third Ultrasonic transducer (US3) at its third resonance frequency (f ₃ ).

Figure 6

6 shows, by way of example, in two extreme configurations, the superposition of a first amplitude spectrum in the form of a first spectral ultrasonic burst amplitude (A1) of a first ultrasonic transducer (US1) and a second amplitude spectrum in the form of a second spectral ultrasonic burst amplitude (A2) of a second ultrasonic transducer (US2) and a third amplitude spectrum in the form of a third spectral ultrasonic burst amplitude (A3) of a third ultrasonic transducer (US3).

Figure 6a

In the 6a the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US12) is smaller than the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1).

In addition, the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US12) is smaller than the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2).

Furthermore, the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) is less than half the sum of the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) and the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2)

In the 6a In addition, the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3) is smaller than the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2).

In addition, the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3) is smaller than the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

Furthermore, the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3) is less than half the sum of the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

In the example of 6a In addition, the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) is approximately equal to the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

In the example of 6a the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) is approximately equal to the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3).

The advantage of selecting the parameters of the different ultrasound transducers lies in the possible combination of the three ultrasound transducers (US1, US2, US3) shown here as examples into a single ultrasound transducer system with increased bandwidth. Instead of ultrasound transducers, ultrasound transmitters can be used to transmit ultrasound bursts and ultrasound receivers to receive them. This means that the transmitting function can be separated from the receiving function. If ultrasound receivers are used instead of ultrasound transducers, the receiving bandwidth of the entire system is also expanded accordingly, which offers many advantages.

For example, it is possible to transmit an ultrasonic burst as an ultrasonic signal through such an ultrasonic sensor system (USS), whose required frequency bandwidth fully utilizes the total frequency bandwidth (Δf _g ) of the ultrasonic sensor system (USS) with several ultrasonic transducers (US1, US2, US3). In the example, the 6a the exemplary total frequency bandwidth (Δf _g ) of the ultrasonic sensor system (USS) comprising the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) and the third ultrasonic transducer (US3) is greater than the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) and greater than the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and greater than the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

This makes it possible for a first ultrasonic transducer to emit more than 50% of the sound energy at a first frequency during the transmission of an ultrasonic burst and a second ultrasonic transducer to emit less than 50% of the sound energy at this first frequency at a first time point during the transmission of the ultrasonic burst, while a second ultrasonic transducer to emit less than 50% of the sound energy at a second frequency at a second time point during the transmission of the ultrasonic burst and the second ultrasonic transducer to emit more than 50% of the sound energy at this second frequency. The first and second times are spaced apart in time, and the first frequency is different from the second frequency.

Conversely, in the case of a receiving operation of the ultrasound transducers, it is possible that at a first point in time during the reception of a reflected ultrasound burst, a first of the ultrasound transducers (US1) receives more than 50% of the received amplitude at a first frequency and a second of the ultrasound transducers (US2) receives less than 50% of the received amplitude at this first frequency, while at a second point in time during the reception of the reflected ultrasound burst, the first of the ultrasound transducers (US1) receives less than 50% of the received amplitude at a second frequency and the second of the ultrasound transducers (US2) receives more than 50% of the received amplitude at this second frequency. The first point in time and the second point in time are spaced apart in time from one another, and the first frequency is different from the second frequency.

This enables the transmission of ultrasonic bursts with more complex coding and a wider frequency bandwidth, which significantly increases the signal-to-noise ratio and thus the range. It also enables the detection of better-resolved reflection signals from the ultrasonic burst.

Figure 6b

In the 6b the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) is greater than the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1).

In addition, the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) is greater than the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2).

Furthermore, the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) is greater than half the sum of the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) and the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2)

In the 6b In addition, the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3) is greater than the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2).

In addition, the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3) is greater than the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

Furthermore, the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3) is greater than half the sum of the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

In the example of 6b In addition, the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) is approximately equal to the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

In the example of 6b the frequency spacing (Δf ₁₂ ) between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) is approximately equal to the frequency spacing (Δf ₂₃ ) between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3).

When selecting the parameters of the ultrasound transducers (US1, US2, US3) according to the 6b Although more complex signals can also be transmitted, a continuous frequency sweep (chirp) is no longer possible, as it leads to significant amplitude drops when the common excitation frequency (f _A ) of the ultra ultrasonic transducers (US, US2, US3) in a frequency range between the amplitude spectra, here the three exemplary spectral ultrasonic burst amplitudes (A1, A2, A3) of the exemplary three ultrasonic transducers (US1, US2, US3). The corresponding amplitude dips of the 6a are considerably lower.

1. a) Im ersten Betriebsmodus werden alle Ultraschall-Transducer (US1, US2, US3) mit dem gleichen Ansteuersignal (AS) und damit mit der gleichen Ansteuermomentanfrequenz (f_A) und phasensynchron angesteuert. Liegt die gemeinsame Ansteuermomentanfrequenz (f_A) innerhalb der Gesamtfrequenzbandbreite (Δf_g) des Ultraschallsensorsystems (USS), so schwingt mindestens einer der Ultraschallsender (US1, US2, US3) an.
2. b) Im zweiten Betriebsmodus wird zumindest einer der Ultraschall-Transducer (US1, US2, US3) mit einem anderen Ansteuersignal (AS1, AS2, AS3) und damit typischerweise nicht mehr mit der gleichen Ansteuermomentanfrequenz (f_A), sondern mit einer anderen Ansteuermomentanfrequenz (f_A1, f_A2, f_A3) und nicht phasensynchron angesteuert.

Basically, two basic operating modes are possible for such an ultrasonic sensor system:

1. a) In the first operating mode, all ultrasonic transducers (US1, US2, US3) are controlled with the same control signal (AS) and thus with the same instantaneous control frequency (f _A ) and in phase synchronization. If the common instantaneous control frequency (f _A ) lies within the total frequency bandwidth (Δf _g ) of the ultrasonic sensor system (USS), at least one of the ultrasonic transmitters (US1, US2, US3) will oscillate.
2. b) In the second operating mode, at least one of the ultrasonic transducers (US1, US2, US3) is controlled with a different control signal (AS1, AS2, AS3) and thus typically no longer with the same control instantaneous frequency (f _A ), but with a different control instantaneous frequency (f _A1 , f _A2 , f _A3 ) and not in phase synchronism.

Figures 7 to 10

The 7 to 10 show basically possible types of a frequency sweep. In a frequency sweep, one or more ultrasonic transducers (US1, US2, US2) are controlled with a control signal (AS), in which the control instantaneous frequency (f _A ) is a function of time and changes during the transmission of an ultrasonic burst (UB) by this ultrasonic transducer. In the examples of the 7 to 10 Various possible ultrasonic sweeps with a non-linear curve of the ultrasonic burst instantaneous frequency (f _m ) are shown. The ultrasonic burst instantaneous frequency (f _m ) is directly linked to the control instantaneous frequency (f _A ) of the control signal (AS) of the ultrasonic transducers (US1, US2, US3) and typically follows this. In the examples of 7 to 10 For example, initially only a first ultrasonic transducer (US1) of the ultrasonic transducers (US1, US2, US3) is used to transmit the ultrasonic burst (UB).

7b represents the course of the first spectral ultrasonic burst amplitude (A1) of the first ultrasonic transducer (US1) as a function of the instantaneous control frequency (f _A ) in the vertical direction corresponding to the 7a represents.

7a represents the first frequency curve (SF1) of the ultrasonic burst instantaneous frequency (f _m ) of a first ultrasonic partial burst of the control signal for generating an ultrasonic burst (UB) by means of the first ultrasonic transducer (US1). The first ultrasonic transducer (US1) has a first upper half-maximum amplitude frequency (f _1o ) and a first lower half-maximum amplitude frequency (f _1u ). At a first transmission start time (t _1s ), in the example, the 7a the first ultrasonic transducer (US1) transmits with an ultrasonic burst instantaneous frequency (f _m ) corresponding to a first start frequency (f _1s ) and emits sound. For this purpose, the first ultrasonic transmitter (US1) is typically controlled with a control signal (AS) with a corresponding instantaneous first start control frequency [f _A1s] . At a first half-frequency time (t _1/50% ), the first ultrasonic transducer (US1) transmits with a first half-frequency (f _1/50% ). For this purpose, the first ultrasonic transducer (US1) is typically controlled with a control signal with a corresponding instantaneous first half-frequency control frequency [f A1 _/50%] . At a first transmission end time (t _1e ), in the example, the 7a The first ultrasonic transducer (US1) starts the transmission process at a first final frequency (f _1e ). For this purpose, the first ultrasonic transmitter (US1) is typically controlled at this first transmission end time (t _1e ) with a control signal having a corresponding instantaneous first final control frequency [f _A1e ].

The first half-frequency control frequency [f _A1/50% ] is calculated as follows in the sense of this document: $$f_{\text{A}1/50\%}=\frac{f_{\text{1s}}-f_{\text{1e}}}{2}+f_{\text{1e}}$$

The first starting frequency (f _1s ) naturally lies between the first upper half-maximum amplitude frequency (f _1o ) and the first lower half-maximum amplitude frequency (f _1u ).

The first half frequency (f _1/50% ) is also located between the first upper half-maximum amplitude frequency (f _1o ) and the first lower half-maximum amplitude frequency (f _1u ).

The first final frequency (f _1e ) also lies between the first upper half-maximum amplitude frequency (f _1o ) and the first lower half-maximum amplitude frequency (f _1u ).

The ultrasonic burst duration (bd) is obtained in the example of 7 as the time difference between the first transmission end time (t _1e ) minus the first transmission start time (t _1s ). $$\text{bd}={\text{t}}_{\text{1e}}-{\text{t}}_{1\text{s}}$$

The half-frequency time point (t _1/50% ) at which the control signal of the first ultrasonic transducer (US1) has the half-frequency control frequency [f _A1/50% ] or at which the transmission frequency of the sound radiation of the first ultrasonic transducer (US1) has the first half-frequency (f _1/50% ) divides the burst duration (bd) into a first temporal burst phase (t _1a ) and an immediately subsequent second temporal burst phase (t _1b ). It is proposed that the first burst phase (t _1a ) be designed to be significantly different in terms of temporal length than the second burst phase (t _1b ). This divides the burst duration (bd) into two temporal burst phases (t _1a , t _1b ) of unequal temporal length. Furthermore, it is proposed that the frequency response of the instantaneous ultrasonic burst frequency (f _m ) be monotonic, preferably even strictly monotonic, either decreasing or increasing. For the sake of simplicity, the initial and final phases of the sound emission for switching the exemplary first ultrasonic transducer (US1) on and off are not taken into account in this monotonicity condition, since the switching-on process is naturally always increasing (increasing from 0 Hz) and the switching-off process is always decreasing (falling to 0 Hz). In the example of the 7a the frequency curve (SF1) of the instantaneous ultrasonic burst frequency (f _m ) of a first ultrasonic subburst is, for example, strictly monotonically decreasing and the first temporal burst phase (t _1a ) is considerably shorter in time than the second temporal burst phase (t _1b ).

Figure 8

8b corresponds to the 7b . Please refer to the corresponding description.

8a corresponds to the 7a with the difference that the frequency curve (SF1) of the ultrasonic burst instantaneous frequency (f _m ) of a first ultrasonic subburst within an ultrasonic burst (UB) is, for example, strictly monotonically increasing and the first temporal burst phase (t _1a ) is considerably shorter in time than the second temporal burst phase (t _1b ).

Figure 9

9b corresponds to the 7b . Please refer to the corresponding description.

9a corresponds to the 7a with the difference that the frequency curve (SF1) of the ultrasonic burst instantaneous frequency (f _m ) of a first ultrasonic subburst within an ultrasonic burst (UB) is, for example, strictly monotonically increasing and the first temporal burst phase (t _1a ) is considerably longer in time than the second temporal burst phase (t _1b ).

Figure 10

10b corresponds to the 7b . Please refer to the corresponding description.

10a corresponds to the 7a with the difference that the frequency curve (SF1) of the instantaneous ultrasonic burst frequency (f _m ) of a first ultrasonic subburst within an ultrasonic burst (UB) is, for example, strictly monotonically decreasing and the first temporal burst phase (t _1a ) is considerably longer in time than the second temporal burst phase (t _1b ).

Figure 11

11 shows an exemplary arrangement consisting of a first ultrasonic transducer (US1) and a second ultrasonic transducer (US2) and a third ultrasonic transducer (US3). In the example of 11 The ultrasonic transducers (US1, US2, US3) are arranged in an isosceles triangle, the edge length of which is less than twice the diameter of the sound radiation surfaces of the ultrasonic transducers (US1, US2, US3). In the example of the 11 The sound radiation surfaces are, for example, circular and, for example, the same size for all three ultrasonic transducers (US1, US2, US3). The first ultrasonic transducer (US1), when it transmits, transmits at a first instantaneous ultrasonic burst frequency (f _1m ). The second ultrasonic transducer (US2), when it transmits, transmits at a second instantaneous ultrasonic burst frequency (f _2m ). The third ultrasonic transducer (US3), when it transmits, transmits at a third instantaneous ultrasonic burst frequency (f _3m ).

Preferably, the ultrasonic transducers (US1, US2, US3) are arranged in an isosceles triangle, the edge lengths of which are less than ten times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and/or less than five times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and/or less than three times the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3) and/or better less than twice the diameter of the sound emitting surfaces of the ultrasonic transducers (US1, US2, US3).

Figure 12

12 corresponds to the 7 with the difference that now a frequency sweep is generated using three ultrasonic sensors (US1, US2, US3).

In the example of 12 For example, all three ultrasound transducers (US1, US2, US3) should be are controlled by the same control signal with the same instantaneous control frequency (f _A ) and therefore emit sound with the same ultrasonic burst instantaneous frequency (f _1m , f _2m , f _3m ). In this respect, in the example of the 12 in contrast to 11 all three exemplary ultrasonic transducers (US1, US2, US3) with a respective ultrasonic burst instantaneous frequency (f _1m , f _2m , f _3m ) corresponding to the instantaneous drive frequency (f _A ) or not or only negligibly if the instantaneous drive frequency (f _A ) is just outside their respective bandwidth (Δf ₁ , Af ₂ , Af ₃ ) of the respective ultrasonic transducer (US1, US2, US3).

The first ultrasonic transducer (US1) has a first spectral ultrasonic burst amplitude (A1) of the first ultrasonic transducer (US1).

The second ultrasonic transducer (US2) has a second spectral ultrasonic burst amplitude (A2) of the second ultrasonic transducer (US2).

The third ultrasonic transducer (US3) has a third spectral ultrasonic burst amplitude (A3) of the third ultrasonic transducer (US3).

These spectral ultrasonic burst amplitudes (A1, A2, A3) are intended to exemplify the situation of the exemplary 6a Refer to the corresponding description of the 6a is expressly referred to here.

In contrast to the transmission of the ultrasonic burst (UB) according to the 7a Ultrasonic burst instantaneous frequencies (f _m ) are now emitted, which lie outside the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1). This means that the frequency bandwidth of the 12 The frequency bandwidth of the emitted ultrasonic burst (UB) is considerably wider than the frequency bandwidth of the 7a emitted ultrasonic bursts (UB).

It is important here that the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) overlaps with the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and that the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) overlaps with the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

This makes it possible for the first frequency curve (SF1) of the instantaneous frequency (f _m ) of the ultrasonic burst within the ultrasonic burst (UB) to follow any curve within the total frequency bandwidth (Δf _g ) of the ultrasonic sensor system (USS) increased by the coupling of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) and the third ultrasonic transducer (US3). 12 only one particularly preferred course of many courses that become possible.

At a third transmission start time (t _3s ) the 12 the third ultrasonic transducer (US3) with the transmission of an ultrasonic partial burst with a third start frequency (f _3s ), which corresponds to a third excitation start frequency [f _A3s ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of 12 The third ultrasonic transducer (US3) then emits the ultrasonic burst with an instantaneous ultrasonic burst frequency (f _m ) that corresponds to the third starting frequency (f _{3s ) at this transmission start time (t 3s )} . The third starting frequency (f _3s ) necessarily lies within the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3). In the example of the 12 the third start frequency (f _3s ) lies outside the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and outside the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1). For the duration of a third single-mode time (smt ₃ ), only the third ultrasonic transducer (US3) transmits. During this period of a third single-mode time (smt ₃ ), significant excitation of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) with the current excitation frequency (f _A ) by means of the control signal (AS) is not possible.

The control device (AV) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 12 Now the current control frequency (f _A ) is continuously decreased within the third single-mode time (smt ₃ ). At a second transmission start time (t _2s ) the 12 the second ultrasonic transducer (US2) also in a fixed phase relationship to the transmission of the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal at a second start frequency (f _2s ), which corresponds to a second excitation start frequency [f _A2s ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of 12 corresponds to a jointly controlled excitation signal. Starting at this second transmission start time (t _2s ), the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) transmit in phase synchronization with the same instantaneous ultrasonic burst frequency (f _m ) in this example. This begins a first dual-mode time (dmt ₂₃ ), during which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) transmit sound simultaneously.

The control device (AV) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 12 Now the instantaneous control frequency (f _A ) within the dual-mode time (dmt ₂₃ ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound, continues to decrease. As a result, the instantaneous ultrasonic burst frequency (f _m ) with which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound also continues to decrease. At a third transmission end time (t _3e ), in the example, the 12 the third ultrasonic transducer (US3) transmits its ultrasonic signal at a third final frequency (f _3e ), which corresponds to a third excitation final frequency [f _A3e ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of 12 This is where the common excitation signal (AS) begins in this example. 12 a second single-mode time (smt ₂ ) in which only the second ultrasonic transducer (US2) emits sound.

The control device (AV) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 12 Now the instantaneous drive frequency (f _A ) continues to decrease continuously within the second single-mode time (smt ₂ ). This also further decreases the instantaneous ultrasonic burst frequency (f _m ) with which the second ultrasonic transducer (US2) emits sound. At a first transmission start time (t _1s ), in the example, the 12 the first ultrasonic transducer (US1) also in a fixed phase relationship to the transmission of the second ultrasonic transducer (US2) with the transmission of an ultrasonic signal at a first start frequency (f _1s ), which corresponds to a first excitation start frequency [f _A1s ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of 12 corresponds to a jointly controlled excitation signal. Starting at this first transmission start time (t _1s ), the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) transmit in phase synchronization with the same instantaneous ultrasonic burst frequency (f _m ) in this example. This begins a second dual-mode time (dmt ₁₂ ) during which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) transmit sound.

The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 12 The instantaneous drive frequency (f _A ) within the dual-mode time (dmt ₁₂ ) during which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound continues to decrease continuously. As a result, the instantaneous ultrasonic burst frequency (f _m ) at which the second ultrasonic transducer (US2) and the first ultrasonic transducer (US1) emit sound also continues to decrease.

At a second transmission end time (t _2e ) the 12 the second ultrasonic transducer (US2) transmits an ultrasonic signal at a second final frequency (f _2e ) which corresponds to a second excitation final frequency [f _A2e ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of 12 This means that at this point in time, the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound with an instantaneous ultrasonic burst frequency (f _m ) that corresponds to this second wide end frequency (f _2e ). In this example, this is where the 12 a first single-mode time (smt ₁ ) in which only the first ultrasonic transducer (US1) emits sound.

The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 12 Now the instantaneous drive frequency (f _A ) within the first single-mode time (smt ₁ ), in which only the first ultrasonic transducer (US1) is emitting sound, continues to decrease. As a result, the instantaneous ultrasonic burst frequency (f _m ) with which the remaining first ultrasonic transducer (US1) is still emitting sound also continues to decrease. At a first transmission end time (t _1e ), in the example, the 12 the first ultrasonic transducer (US1) transmits an ultrasonic signal at a first final frequency (f _1e ) corresponding to a first excitation final frequency [f _A1e ] for the frequency of the three ultrasonic transducers (US1, US2, US3) in the example of 12 This means that at this point in time the first ultrasonic transducer (US1) emits sound with an instantaneous ultrasonic burst frequency (f _m ) that corresponds to this second wide end frequency (f _2e ). In this example, this ends the 12 the emission of the ultrasonic burst (US) and thus the burst duration (bd). The sound emission then ends altogether, and the ultrasonic burst (UB) is terminated.

Figure 13

13 shows a simplified and schematic example of a system for generating the exemplary frequency response of the 12 For example, an ultrasonic sensor system (USS) is used 11 used. A control device (AV) can be part of the ultrasonic sensor system (USS) or can be arranged outside the ultrasonic sensor system (USS).

The control device (AV) generates one or more control signals (AS) that here at is fed, for example, in parallel to a plurality of ultrasonic transducers (US1, US2, US3). Thus, the ultrasonic transducers (US1, US2, US3) of the plurality of ultrasonic transducers (US1, US2, US3) are excited to oscillate at the same control frequency (f _A ) of the control signal (AS). However, the ultrasonic transducers (US1, US2, US3) only oscillate when the instantaneous control frequency (f _A ) of the control signal (AS) lies within their respective bandwidth (Δf ₁ , Δf ₂ , Δf ₃ ).

Figure 14

14 corresponds in essential parts to the 12 . However, the excitation signal (AS) now temporarily comprises more than one excitation frequency (f _A ). For example, the control signal (AS) can comprise a first excitation frequency (f _A1 ) of a first excitation signal component, a second excitation frequency (f _A2 ) of a second excitation signal component, and a third excitation frequency (f _A3 ) of a third excitation signal component. The first excitation signal component, the second excitation signal component, and the third excitation signal component are then preferably superimposed by summation to form the actual excitation signal (AS).

In the example of 14 In a first phase of the exemplary ultrasonic burst (UB), all three ultrasonic transducers (US1, US2, US3) are to be controlled with the same control signal (AS) with the same first control instantaneous frequency (f _A1 ). In this case, in the example, the 14 in contrast to 11 all three exemplary ultrasonic transducers (US1, US2, US3) again with the frequencies corresponding to the instantaneous control frequencies (f _A1 , f _A2 ) or not or only negligibly if the instantaneous control frequencies (f _A1 , f _A2 ) are just outside their respective bandwidths (Δf ₁ , Δf ₂ , Δf ₃ ).

The first ultrasound transducer (US1) has, as in 12 a first spectral ultrasonic burst amplitude (A1) of the first ultrasonic transducer (US1).

The second ultrasound transducer (US2) has the following characteristics: 12 a second spectral ultrasonic burst amplitude (A2) of the second ultrasonic transducer (US2).

The third ultrasound transducer (US3) has the following characteristics: 12 a third spectral ultrasonic burst amplitude (A3) of the third ultrasonic transducer (US3).

These spectral ultrasonic burst amplitudes (A1, A2, A3) should be used here as in 12 exemplary of the situation of the exemplary 6a Refer to the corresponding description of the 6a is expressly referred to here.

In contrast to the transmission of the ultrasonic burst (UB) according to the 12 are now in the 14 temporarily more than two ultrasonic burst instantaneous frequencies within the radiated ultrasonic burst. That is, the frequency bandwidth of the 14 transmitted ultrasonic burst (UB) is also, in relation to individual transmission times during the burst duration (bd) of the ultrasonic burst (UB), at least temporarily considerably wider than the instantaneous frequency bandwidth of the 12 emitted ultrasonic bursts (UB).

It is also important here that the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1) overlaps with the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and that the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) overlaps with the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3).

This makes it possible for the first frequency curve (SF1) of the first excitation frequency (f _A1 ) of a first signal component of the control signal (AS) for generating an ultrasonic burst (UB) by means of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) and the third ultrasonic transducer (US3) to follow any curve within the thus enlarged overall bandwidth as the first ultrasonic subburst within the ultrasonic burst (UB) and thus the first frequency curve (SF1) of the instantaneous ultrasonic frequency (f _m1 ). 14 only one particularly preferred course of many courses that become possible.

Furthermore, it is also possible that, in addition to the first frequency curve (SF1), a second frequency curve (SF2) of a second ultrasonic burst instantaneous frequency (f _m2 ) of a second ultrasonic subburst within an ultrasonic burst (UB) and, if appropriate, a third frequency curve (SF3) (not shown) of a third ultrasonic burst instantaneous frequency (f _m3 ) of a third ultrasonic subburst within the ultrasonic burst (UB) follow any second curve or third, not shown curve within the thus enlarged total bandwidth, independent of the first frequency curve (SF1) of the first ultrasonic instantaneous frequency (f _m1 ). In this respect, the 14 only a particularly preferred course of many possible courses and frequency course combinations. Theoretically, n frequency courses, with n as a positive integer, n ultrasonic burst instantaneous frequencies of Ultrasonic subbursts within the ultrasonic burst (UB) follow any curves within the thus enlarged total bandwidth independent of the first frequency response (SF1) of the first ultrasonic instantaneous frequency (f _m1 ) (f _A1 )

At a third transmission start time (t _3s ) the 14 the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal with a third start frequency (f _3s ) as the first ultrasonic instantaneous frequency (f _m1 ), which corresponds to a third excitation start frequency [f _A3s ] for the first excitation frequency (f _A1 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 jointly driving excitation signal (AS). The third start frequency (f _3s ) lies within the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3). In the example of the 14 the third start frequency (f _3s ) lies outside the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and outside the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1). For the duration of a third single-mode time (smt ₃ ), only the third ultrasonic transducer (US3) transmits at the first instantaneous ultrasonic frequency (f _m1 ). During this period of a third single-mode time (smt ₃ ), significant excitation of the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) with the instantaneous first excitation frequency (f _A1 ) is not possible.

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 13 Now the instantaneous first control frequency (f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the third single-mode time (smt ₃ ) continuously decreases. At a second transmission start time (t _2s ) in the example the 14 the second ultrasonic transducer (US2) also in a fixed phase relationship to the transmission of the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal with a first instantaneous ultrasonic frequency (f _m1 ) at a second start frequency (f _2s ), which corresponds to a second excitation start frequency [f _A2s ] for the instantaneous first control frequency (f _A1 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 jointly controlled excitation signal (AS). This begins a dual-mode time (dmt ₂₃ ), during which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound at the first instantaneous ultrasonic frequency (f _m1 ).

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the first instantaneous control frequency (f _A1 ) within the dual-mode time (dmt ₂₃ ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound with the first instantaneous ultrasonic frequency (f _m1 ), continues to be continuously transmitted. At a third transmission end time (t _3e ), in the example, the 14 the third ultrasonic transducer (US3) transmits an ultrasonic signal with the first instantaneous ultrasonic frequency (f _m1 ) at a third end frequency (f _3e ), which corresponds to a third excitation end frequency [f _A3e ] for the instantaneous first control frequency (f _A1 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 This is where the common excitation signal (AS) begins in this example. 14 a second single-mode time (smt ₂ ) in which only the second ultrasonic transducer (US2) emits sound with the first instantaneous ultrasonic frequency (f _m1 ).

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the instantaneous first control frequency (f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the second single-mode time (smt ₂ ) continues to decrease continuously. At a first transmission start time (t _1s ) in the example, the 14 the first ultrasonic transducer (US1) also in a fixed phase relationship to the transmission of the second ultrasonic transducer (US2) with the transmission of an ultrasonic signal of the first ultrasonic instantaneous frequency (f _m1 ) at a first start frequency (f _1s ), which corresponds to a first excitation start frequency [f _A1s ] for the control frequency (f _A1 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 jointly controlled excitation signal (AS). This begins a dual-mode time (dmt ₁₂ ) in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound at the first instantaneous ultrasonic frequency (f _m1 ).

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the current first control frequency (f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the dual-mode time (dmt ₁₂ ), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound with the first instantaneous ultrasonic frequency (f _m1 ), continues to be continuously reduced. At a second transmission end time (t _2e ), in the example, the 14 the second ultrasonic transducer (US2) transmits an ultrasonic signal with the first ultrasonic instantaneous frequency (f _m1 ) at a second end frequency (f _2e ) which corresponds to a second excitation end frequency [f _A2e ] for the first drive frequency (f _A1 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 This is where the common excitation signal (AS) begins in this example. 14 a first single-mode time (smt ₁ ) in which only the first ultrasonic transducer (US1) emits sound with the first instantaneous ultrasonic frequency (f _m1 ).

The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 then the instantaneous first control frequency (f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the first single-mode time (smt ₁ ), in which only the first ultrasonic transducer (US1) emits sound with the first instantaneous ultrasonic frequency (f _m1 ), continues to decrease continuously. At a first transmission end time (t _1e ), in the example, the 14 the first ultrasonic transducer (US1) transmits the proportional ultrasonic signal with the first instantaneous ultrasonic frequency (f _m1 ) at a first end frequency (f _1e ), which corresponds to a first excitation end frequency [f _A1e ] for the instantaneous first control frequency (f _A1 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 This is where the excitation signal ends in this example. 12 the emission of the ultrasonic burst (US) and thus the burst duration (bd). The sound emission then ends.

In contrast to the 12 Now, at least for a temporal portion of the burst duration (bd), parallel to the first ultrasound subburst having the first frequency profile (SF1) of the first instantaneous ultrasound frequency (f _m1 ), a second ultrasound burst component having a second frequency profile (SF2) of the second instantaneous ultrasound frequency (f _m2 ) is superimposed, preferably by summation, in the control signal (AS). Thus, in the time periods of this superposition, the control signal (AS) typically has a first instantaneous ultrasound frequency (f _m1 ) as the first frequency component and a second instantaneous ultrasound frequency (f _m2 ) as the frequency components.

In the example of 14 is, for example, in the first single-mode time (smt ₁ ) by generating this second frequency curve (SF2) of the second ultrasonic burst instantaneous frequency (f _m2 ) of a second ultrasonic subburst within an ultrasonic burst (UB) from the structure of the ultrasonic burst of the 12 deviated.

At a further third transmission start time (t _3sb ) the 14 the third ultrasonic transducer (US3) with the transmission of an additional ultrasonic partial burst with the third start frequency (f _3s ) as the second ultrasonic instantaneous frequency (f _m2 ), which again corresponds to the third excitation start frequency [f _A3s ] for the second excitation frequency (f _A2 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 jointly controlling excitation signal (AS). From this point in time, the third transmission start time (t _3sb ), the control signal (AS) therefore includes not only a first ultrasonic partial burst with a first instantaneous ultrasonic frequency (f _m1 ), but also a second ultrasonic partial burst with a second instantaneous ultrasonic frequency (f _m2 ). The third start frequency (f _3s ) is, as before, typically within the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3). It is assumed here to be unchanged. In the example of the 14 the third start frequency (f _3s ) lies outside the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2) and outside the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1). For the duration of a third dual-mode time (dmt ₁₃ ), in the example, the 14 the third ultrasonic transducer (US3) with a second instantaneous ultrasonic frequency (f _m2 ) and the first ultrasonic transducer (US1) with a first instantaneous ultrasonic frequency (f _m1 ) each emit a sound signal.

Since the first instantaneous control frequency (f _A1 ) in this third dual-mode time (dmt ₁₃ ) is below the third lower half-maximum amplitude frequency (f _3u ), the third ultrasonic transducer (US3) does not oscillate at the first instantaneous control frequency (f _A1 ).

Since the first instantaneous control frequency (f _A1 ) in this third dual-mode time (dmt ₁₃ ) is also below the second lower half-maximum amplitude frequency (f _2u ), the second ultrasonic transducer (US2) also does not oscillate at the first instantaneous control frequency (f _A1 ).

Since the second instantaneous drive frequency (f _A2 ) in this third dual-mode time (dmt ₁₃ ) is above the second upper half-maximum amplitude frequency (f _2o ), the second ultrasonic transducer (US2) does not oscillate at the second instantaneous drive frequency (f _A2 ).

Since the second instantaneous drive frequency (f _A2 ) in this third dual-mode time (dmt ₁₃ ) is above the first upper half-maximum amplitude frequency (f _1o ), the first ultrasonic transducer (US1) does not oscillate at the second instantaneous drive frequency (f _A2 ).

During this period of a third dual-mode time (dmt ₁₃ ), a significant excitation of the first ultrasound transducer (US1) and the second ultrasound transducer (US2) with the current second excitation frequency (f _A2 ) is not possible.

During this period, which is a third dual-mode time (dmt ₁₃ ), a significant excitation of the third ultrasound transducer (US3) and the second ultrasound transducer (US2) with the current first excitation frequency (f _A1 ) is not possible.

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the instantaneous first control frequency (f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) and the instantaneous second control frequency (f _A2 ) and thus the second instantaneous ultrasonic frequency (f _m2 ) within the third dual-mode time (dmt ₁₃ ) together continuously decrease. At a further second transmission start time (t _2sb ) in the example the 14 the second ultrasonic transducer (US2) also in a fixed phase relationship to the transmission of the third ultrasonic transducer (US3) with the transmission of an ultrasonic signal with the second ultrasonic instantaneous frequency (f _m2 ) at a second start frequency (f _2s ), which corresponds to a second excitation start frequency [f _A2s ] for the instantaneous second control frequency (f _A2 ) of the second signal component of the three ultrasonic transducers (US1, US2, US3) in the example of 14 jointly controlled excitation signal (AS). This begins a tri-mode time (tmt ₁₂₃ ) in which the third ultrasonic transducer (US3) emits sound at the second instantaneous ultrasonic frequency (f _m2 ), the second ultrasonic transducer (US2) emits sound at the second instantaneous ultrasonic frequency (f _m2 ), and the first ultrasonic transducer (US1) emits sound at the first instantaneous ultrasonic frequency (f _m1 ).

Since the first instantaneous control frequency (f _A1 ) in this third dual-mode time (dmt ₁₃ ) is below the third lower half-maximum amplitude frequency (f _3u ), the third ultrasonic transducer (US3) does not oscillate at the first instantaneous control frequency (f _A1 ).

Since the first instantaneous control frequency (f _A1 ) in this third dual-mode time (dmt ₁₃ ) is also below the second lower half-maximum amplitude frequency (f _2u ), the second ultrasonic transducer (US2) also does not oscillate at the first instantaneous control frequency (f _A1 ).

Since the second instantaneous control frequency (f _A2 ) in this third dual-mode time (dmt ₁₃ ) is now below the second upper half-maximum amplitude frequency (f _2o ) and above the second lower half-maximum amplitude frequency (f _2u ), the second ultrasonic transducer (US2) now oscillates at the second instantaneous control frequency (f _A2 ) and emits sound at the second ultrasonic instantaneous frequency (f _m2 ).

Since the second instantaneous drive frequency (f _A2 ) in this third dual-mode time (dmt ₁₃ ) is above the first upper half-maximum amplitude frequency (f _1o ), the first ultrasonic transducer (US1) does not oscillate at the second instantaneous drive frequency (f _A2 ) and emits sound of the first ultrasonic instantaneous frequency (f _m1 ).

During this period of a third tri-mode time (tmt ₁₂₃ ), a significant excitation of the first ultrasound transducer (US1) with the current second excitation frequency (f _A2 ) is not possible.

During this period of a third tri-mode time (tmt ₁₂₃ ), a significant excitation of the third ultrasound transducer (US3) and the second ultrasound transducer (US2) with the current first excitation frequency (f _A1 ) is not possible.

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the first instantaneous control frequency (f _A1 ) and the second instantaneous control frequency (f _A2 ) and thus the first ultrasonic instantaneous frequency (f _m1 ) and the second ultrasonic instantaneous frequency (f _m2 ) within the tri-mode time (tmt ₁₂₃ ), in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) and the first ultrasonic transducer (US1) emit sound, continue to decrease continuously. At a further third transmission end time (t _3eb ), the 14 the third ultrasonic transducer (US3) transmits the ultrasonic signal with the second instantaneous ultrasonic frequency (f _m2 ) at a third end frequency (f _3e ), which corresponds to a third excitation end frequency [f _A3e ] for the instantaneous second control frequency (f _A2 ) of the signal portion of the three ultrasonic transducers (US1, US2, US3) in the example of 14 This is where the common excitation signal (AS) begins in this example. 14 a fourth dual-mode time (dmt _12b ) in which only the second ultrasonic transducer (US2) with the second instantaneous ultrasonic frequency (f _m2 ) and the first ultrasonic transducer (US1) with the first instantaneous ultrasonic frequency (f _m1 ) emit sound.

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the instantaneous first control frequency (f _A1 ) and the instantaneous second control frequency (f _A2 ) and thus the first ultrasonic instantaneous frequency (f _m1 ) and the second ultrasonic instantaneous frequency (f _m2 ) within the fourth dual-mode time (dmt _12b ) continue to decrease continuously. At a first transmission start time (t _1s ) in the example, the 14 the first ultrasonic transducer (US1) also in a fixed phase relationship to the transmission of the second ultrasonic transducer (US2) with the transmission of a second ultrasonic subburst of the ultrasonic signal at a first start frequency (f _1s ) which corresponds to a first Excitation start frequency [f _a1s ] for the second control frequency (f _A2 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 jointly controlled excitation signal (AS). The special feature here is that the first ultrasonic transducer (US1) must oscillate at two frequencies: the first instantaneous ultrasonic frequency (f _m1 ) and the second instantaneous ultrasonic frequency (f _m2 ). This is not always possible. As a rule, the instantaneous control frequencies (f _A1 , f _A2 ) are so close to one another at this point in time that the oscillation of the first ultrasonic transducer (US1) beats.

This begins a second tri-mode time (dmt ₁₂ ), in which the first ultrasonic transducer (US1) emits sound at the first instantaneous ultrasonic frequency (f _m1 ) and simultaneously at the second instantaneous ultrasonic frequency (f _m2 ) and the second ultrasonic transducer (US2) emits sound at the second instantaneous ultrasonic frequency (f _m2 ), whereby the first ultrasonic transducer oscillates at two instantaneous ultrasonic frequencies (f _m1 and f _m2 ).

The control device (AS) of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Now the instantaneous first control frequency (f _A1 ) and the instantaneous second control frequency (f _A2 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) and the second instantaneous ultrasonic frequency (f _m2 ) within the second tri-mode time (tmt ₁₁₂ ), in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound, continue to decrease continuously. At a second transmission end time (t _2e ), in the example, the 14 the second ultrasonic transducer (US2) transmits an ultrasonic signal with the second ultrasonic instantaneous frequency (f _m2 ) at a second end frequency (f _2e ) which corresponds to a second excitation end frequency [f _A2e ] for the second control frequency (f _A1 ) of the second signal component of the three ultrasonic transducers (US1, US2, US3) in the example of 14 This is where the common excitation signal (AS) begins in this example. 14 a final dual-mode time (dmt _11b ), in which only the first ultrasonic transducer (US1) emits sound. The first ultrasonic transducer (US1) initially oscillates at two instantaneous ultrasonic frequencies (f _m1 , f _m2 ). Towards the end, the 14 the frequency difference between the first ultrasonic instantaneous frequency (f _m1 ) and the second ultrasonic instantaneous frequency (f _m2 ) until finally the two ultrasonic instantaneous frequencies (f _m1 , f _m2 ) in the example of 14 are equal.

The control device of the three ultrasonic transducers (US1, US2, US3) lowers in the example of the 14 Thus, the current first control frequency (f _A1 ) and the current second control frequency (f _A2 ) continue to decrease continuously within the last dual-mode time (dmt _11b ), in which only the first ultrasonic transducer (US1) emits sound. At a first transmission end time (t _1e ), the 14 the first ultrasonic transducer (US1) transmits the proportional ultrasonic signal at a first final frequency (f _1e ), which corresponds to a first excitation final frequency [f _A1e ] for the current first control frequency (f _A1 ) and the current second control frequency (f _A2 ) of the three ultrasonic transducers (US1, US2, US3) in the example of 14 The excitation signal (AS) that is to be controlled jointly ends the 14 the emission of the ultrasonic burst (US) and thus the burst duration (bd). The sound emission then ends.

Figure 15

15 shows a simplified and schematic example of a system for generating the exemplary frequency response of the following 16 For example, an ultrasonic sensor system (USS) is used 11 used.

In contrast to the system of 13 The first ultrasonic transducer (US1) now has its own first control device (AV1). The second ultrasonic transducer (US2) now has its own second control device (AV2). The third ultrasonic transducer (US3) now has its own third control device (AV3).

The first control device (AV1) controls the first ultrasonic transducer (US1) using a first control signal (AS1).

The second control device (AV2) controls the second ultrasonic transducer (US2) using a second control signal (AS2).

The third control device (AV3) controls the third ultrasonic transducer (US3) using a third control signal (AS3).

A control unit (SG) controls the first control device (AV1) via a data bus (DB).

The control unit (SG) controls the second control device (AV2) via the data bus (DB).

The control unit (SG) controls the third control device (AV3) via the data bus (DB).

Preferably, the control devices (AV1, AV2, AV3) are synchronized via the data bus. In this case, the control devices (AV1, AV2, AV3) preferably contain their own time bases, for example, clock generators or timers, which maintain synchronization for a sufficiently long period of time without additional synchronization signals from the control unit (SG).

Thus, the ultrasonic transducers (US1, US2, US3) of the plurality of ultrasonic transducers (US1, US2, US3) can be excited to oscillate individually and independently with identical or unequal control frequencies (f _A1 , f _A2 , f _A3 ) of the control signals (AS1, AS2, AS3). However, the ultrasonic transducers (US1, US2, US3) only oscillate when the instantaneous control frequencies (f _A1 , f _A2 , f _A3 ) of the respective control signals (AS1, AS2, AS3) lie within their respective, associated bandwidths (Δf ₁ , Δf ₂ , Δf ₃ ).

Figure 16

16 corresponds to the 12 with the difference that a first frequency curve (SF1) of the first instantaneous excitation frequency (f _A1 ) of a first signal component of the control signal (AS) is used to generate an ultrasonic burst (UB) together with a second frequency curve (SF2) of the second instantaneous excitation frequency (f _A2 ) of a second signal component of the control signal (AS) to generate an ultrasonic burst (UB) and together with a third frequency curve (SF3) of the third instantaneous excitation frequency (f _A3 ) of a third signal component of the control signal (AS) to generate an ultrasonic burst (UB). As a result, the ultrasonic sensor system (USS) emits, at least temporarily, an ultrasonic signal which comprises a first ultrasonic partial burst with a first instantaneous ultrasonic frequency (f _m1 ) and a second ultrasonic partial burst with a second instantaneous ultrasonic frequency (f _m2 ) and a third ultrasonic partial burst with a third instantaneous ultrasonic frequency (f _m3 ) in a summed and superimposed manner.

The corresponding signal can be transmitted by means of a device corresponding 15 , as well as by means of a device corresponding 13 be generated.

Since the first frequency response (SF1) remains entirely within the first bandwidth (Δf ₁ ) of the first ultrasonic transducer (US1), it is possible to generate this portion of the ultrasonic burst using only the first ultrasonic transducer (US1), with the first ultrasonic transducer then being controlled using a first control signal (AS1) that preferably only includes the first control frequency (f _A1 ). The first ultrasonic transducer (US1) then emits a first ultrasonic subburst having the first instantaneous ultrasonic frequency (f _m1 ), which corresponds to the first control frequency (f _A1 ).

Since the second frequency response (SF2) remains entirely within the second bandwidth (Δf ₂ ) of the second ultrasonic transducer (US2), it is possible to generate this portion of the ultrasonic burst using only the second ultrasonic transducer (US2), with the second ultrasonic transducer then being controlled using a second control signal (AS2) that preferably only includes the second control frequency (f _A2 ). The second ultrasonic transducer (US2) then emits a second ultrasonic subburst with the second instantaneous ultrasonic frequency (f _m2 ), which corresponds to the second control frequency (f _A2 ).

Since the third frequency response (SF3) remains entirely within the third bandwidth (Δf ₃ ) of the third ultrasonic transducer (US3), it is possible to generate this portion of the ultrasonic burst using only the third ultrasonic transducer (US3). The third ultrasonic transducer is then controlled using a third control signal (AS3) that preferably only includes the third control frequency (f _A3 ). The third ultrasonic transducer (US3) then emits a third ultrasonic subburst with the third instantaneous ultrasonic frequency (f _m3 ), which corresponds to the third control frequency (f _A3 ).

At a first transmission start time (t _1s ), the first ultrasonic transducer (US1) begins to oscillate at the first start frequency (f _1s ) as the first instantaneous ultrasonic frequency (f _m1 ) and to emit its sound signal at this first instantaneous ultrasonic frequency (f _m1 ). For this purpose, a control device (AV) or a first control device (AV1) controls the first ultrasonic transducer (US1) with a momentary first control frequency (f _A1 ), which essentially corresponds to the desired first instantaneous ultrasonic frequency (f _m1 ) of the sound emission. In the example of the 15 the control device (AV) or the first control device (AV1) reduces the instantaneous first control frequency (f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) of the sound emission of the first ultrasonic transducer (US1) as time progresses. At a first transmission end time (t _1e ), the first ultrasonic transducer (US1) then stops the sound emission at a first end frequency (f _1e ) as the first instantaneous ultrasonic frequency (f _m1 ).

At a second transmission start time (t _2s ), the second ultrasound transducer then begins (US2) with the second starting frequency (f _2s ) as the second instantaneous ultrasonic frequency (f _m2 ) and to emit its sound signal with this second instantaneous ultrasonic frequency (f _m2 ). For this purpose, a control device (AV) or a second control device (AV2) controls the second ultrasonic transducer (US2) with a momentary second control frequency (f _A2 ) which essentially corresponds to the desired second instantaneous ultrasonic frequency (f _m2 ). In the example of the 15 the control device (AV) or the second control device (AV2) reduces the instantaneous second control frequency (f _A2 ) and thus the second instantaneous ultrasonic frequency (f _m2 ) of the sound emission of the second ultrasonic transducer (US2) as time progresses. At a second transmission end time (t _2e ), the second ultrasonic transducer (US2) then ceases sound emission at a second end frequency (f _2e ) as the second instantaneous ultrasonic frequency (f _m2 ).

At a third transmission start time (t _3s ), the third ultrasonic transducer (US3) begins to oscillate at the third start frequency (f _3s ) as the third instantaneous ultrasonic frequency (f _m3 ) and to emit its sound signal at the third instantaneous ultrasonic frequency (f _m3 ). For this purpose, a control device (AV) or a third control device (AV3) controls the third ultrasonic transducer (US3) with a momentary third control frequency (f _A3 ), which essentially corresponds to the desired instantaneous oscillation frequency. In the example of the 15 The control device (AV) or the third control device (AV3) reduces the current third control frequency (f _A3 ) and thus the third instantaneous ultrasonic frequency (f _m3 ) of the sound emission of the third ultrasonic transducer (US3) as time progresses. At a third transmission end time (t _3e ), the third ultrasonic transducer (US3) then stops the sound emission at a third end frequency (f _3e ) as the third instantaneous ultrasonic frequency (f _m3 ).

In the example of 16 The first start time (t _1s ) occurs before the second start time (t _2s ) and the third start time (t _3s ). This results in a first single-mode time (smt ₁ ) in which only the first ultrasonic transducer (US1) emits sound at the first instantaneous ultrasonic frequency (f _m1 ).

In the example of 16 The second start time (t _2s ) occurs after the first start time (t _1s ) and before the third start time (t _3s ). This results in a first dual-mode time (dmt ₁ ) in which only the first ultrasonic transducer (US1) with the first instantaneous ultrasonic frequency (f _m1 ) and the second ultrasonic transducer (US2) with the second instantaneous ultrasonic frequency (f _m2 ) emit sound with different instantaneous ultrasonic frequencies (f _m1 , f _m2 ).

After the third start time (t _3s ), the third ultrasonic transducer (US3) also begins to emit sound at the third instantaneous ultrasonic frequency (f _m3 ). This results in a first tri-mode time (tmt) in a period beginning with the third start time (t _3s ) and ending with the first end time (t _1e ) in which all three ultrasonic transducers (US1, US2, US3) emit sound at three different frequencies. The first ultrasonic transducer (US1) emits sound at the first instantaneous ultrasonic frequency (f _m1 ). The second ultrasonic transducer (US2) emits sound at the second instantaneous ultrasonic frequency (f _m2 ). The third ultrasonic transducer (US3) emits sound at the third instantaneous ultrasonic frequency (f _m3 ).

In the example of 16 The first end time (t _1e ) occurs before the second end time (t _2e ) and the third end time (t _3e ). This results in a second dual-mode time (dmt ₂ ) in which only the second ultrasonic transducer (US2) emits sound at the second instantaneous ultrasonic frequency (f _m2 ) and the third ultrasonic transducer (US3) emits sound at the third instantaneous ultrasonic frequency (f _m3 ). The second dual-mode time (dmt ₂ ) ends with the second end time (t _2e ).

In the example of 16 The second end time (t _2e ) occurs after the first end time (t _1e ) and before the third end time (t _3e ). This results in a second single-mode time (smt ₂ ) in which only the third ultrasonic transducer (US3) emits sound at the third instantaneous ultrasonic frequency (f _m3 ). The second single-mode time (smt ₂ ) ends with the third end time (t _3e ). This also marks the end of the ultrasonic burst.

Figure 17

17 corresponds to the 12 with the difference that now a first frequency curve (SF1) of the first instantaneous ultrasonic frequency (f _m1 ) of a first ultrasonic partial burst corresponding to the frequency curve of the first instantaneous excitation frequency (f _A1 ) of a first signal component of the control signal (AS) for generating an ultrasonic burst (UB) together with a second frequency curve (SF2) of the second instantaneous ultrasonic frequency (f _m2 ) of a second ultrasonic partial burst corresponding to the second instantaneous excitation frequency (f _A2 ) of a second signal component of the control signal (AS) for generating an ultrasonic burst (UB) and together with a third frequency curve (SF3) of the third instantaneous ultrasonic frequency (f _m3 ) corresponding to the third instantaneous excitation frequency (f _A3 ) of a third signal component of the control signal (AS) to generate an ultrasonic burst (UB). In contrast to the previous 16 All frequency curves (SF1, SF2, SF3) now end at a common end frequency (f _e ) as the respective instantaneous ultrasonic frequency (f _m1 , f _m2 , f _m3 ) at a common end time (t _e ). This common end frequency (f _e ) is chosen so that it can be generated by all three exemplary ultrasonic transducers (US1, US2, US3). Two of the frequency curves are monotonically decreasing, one monotonically increasing.

Figure 18 & Figure 19

The sound radiation of the ultrasonic sensor system (USS) corresponds to a multipole expansion of a spherical wave function, neglecting the distance between the ultrasonic sensors (US1, US2, US3) and the dimensions of the ultrasonic sensor system (USS) itself. This means that the sound radiation lobe of an ultrasonic transducer (US1, US2, US3) of the ultrasonic sensor system (USS) each has an aperture angle. The sound radiation lobe of an ultrasonic sensor has a lobe axis. If the sound radiation lobe is cut perpendicular to the lobe axis in a cross-section, the intensity distribution of the sound in this cross-section is generally not rotationally symmetrical around the point where the lobe axis intersects this cross-section plane, but rather elliptical. Preferably, the aperture angle of the sound radiation of an ultrasonic sensor in the vertical direction is often different from the aperture angle of the sound radiation in the horizontal direction. 18 The horizontal opening angles are designated with the index H and the vertical opening angles with the index V. The 18a outlines the situation in supervision. The 18b sketches the situation in side view.

The sound beam of the first ultrasonic transducer (US1) of the ultrasonic system (USS) has the vertical opening angle α _V and the horizontal opening angle α _H .

The sound beam of the second ultrasonic transducer (US2) of the ultrasonic system (USS) has the vertical opening angle β _V and the horizontal opening angle β _H .

The sound beam of the third ultrasonic transducer (US3) of the ultrasonic system (USS) has the vertical opening angle γ _v and the horizontal opening angle γ _H .

In the example of 18 For example, the opening angles of the first ultrasonic transducer (US1) are designed to be larger than the opening angles of the second ultrasonic transducer (US2) and larger than the opening angles of the third ultrasonic transducer (US3).

In the example of 18 the opening angles of the second ultrasonic transducer (US2) are smaller than the opening angles of the first ultrasonic transducer (US1) and larger than the opening angles of the third ultrasonic transducer (US3).

The different aperture angles can be achieved, for example, by adjusting the membrane size relative to the sound wavelength. The resonance frequencies can be adjusted by material selection and thickness. The choice of excitation frequency (f _A1 , f _A2 , f _A3 ) of the respective ultrasonic transducer (US1, US2, US3) also changes the dimensions of the radiation beam.

This has the advantage that at different excitation frequencies the reflections of objects (O1, O2) that are equally far away from the ultrasound system (see also 19 ) by the spectral composition of the reflected signal. This makes it possible to determine the angle.

Figure 20

20 illustrates how the different types of modulation described above can now be used when approaching an important object (O), for example an obstacle.

In the example of 20 the burst duration (bd) is shortened as the object (O) is approached.

The number of simultaneously transmitted frequency responses (SF1, SF2, SF3) increases from two to three when the distance between the ultrasonic sensor system (USS) and the object (O, O1, O2) falls below a certain threshold. The number of simultaneously transmitted frequency responses (SF1, SF2, SF3) therefore changes as the sensor approaches the object (O). Within an ultrasonic burst, the number of frequency responses initially increases from 1 to 2. As the sensor approaches closer, the number of frequency responses within an ultrasonic burst then increases from 1 to 3.

The frequency curves are in the example of 20 all always decrease strictly monotonically within an ultrasonic burst, whereby the decay rate of the instantaneous ultrasonic frequencies (f _m1 , f _m2 , f _m3 ) and thus that of the excitation frequencies (f _A ) decreases within an ultrasonic burst (UB). The starting frequency (f _1s ) of the first frequency response (SF1) within an ultrasonic burst (UB) is changed as the object (O) approaches. First, the starting frequency (f _1s ) of the first frequency response (SF1) within an ultrasonic burst is increased as the object (O) approaches, and then decreases again as the object approaches. All ultrasonic bursts in the example of the 20 a single-mode time (smt), in which only the ultrasonic subburst with the first frequency response (SF1) is transmitted. One time period of the ultrasonic burst transmission (UB) has a dual-mode time (dmt), in which only the ultrasonic subbursts with the first frequency response (SF1) and with the second frequency response (SF3) are transmitted. Another part of the ultrasonic bursts has a tri-mode time (tmt), in which the ultrasonic subbursts with the first frequency response (SF1), with the second frequency response (SF3), and with the third frequency response (SF3) are transmitted.

Figure 21

21 illustrates the situation when using two ultrasonic sensor systems (USS1, USS2).

In this example, for better explanation, each of the two exemplary ultrasonic sensor systems (USS1, USS2) corresponds approximately to the exemplary ultrasonic sensor system (USS) of the 11 .

Each of the ultrasonic sensor systems (USS1, USS2) receives the corresponding 18 and different instantaneous ultrasonic frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic sensor system, three different ultrasonic reflection signals with different instantaneous ultrasonic frequencies (f _m1 , f _m2 , f _m3 ). These three example ultrasonic reflection signals can be evaluated in the ultrasonic sensor system (USS1, USS2) and then transmitted to a control unit (SG) or can be compressed without being evaluated and largely unprocessed, transmitted to a control unit (SG), and then evaluated in the control unit (SG). Depending on the distance (D, s1, s2) of the object (O) from the respective ultrasonic sensor system (USS1, USS2), the ultrasonic reflection signal arrives at the respective ultrasonic sensor system (USS1, USS2) at different times, which can also be evaluated.

Figure 22

22 shows the effect of the different ultrasound bursts with regard to their Doppler resistance.

22 shows four examples of the influence of ultrasonic burst frequency bandwidth and frequency modulation curvature on Doppler-related range errors at a vehicle speed of 8 ms ^-1 . The top row shows spectrograms of four ultrasonic burst echo pairs. The bottom row shows the envelopes of the corresponding cross-correlation function (CCF signal) between the ultrasonic burst signal emitted by the moving vehicle and the signal reflected by a stationary object after reception by the ultrasonic sensor system located in the moving vehicle. The arrows indicate the actual time delay of 8 ms between the time of emission and the time of reception of the echo. The vertical lines show the position of the peak in the CCF signal.

As can easily be seen, a greater broadband of the ultrasound burst leads to a reduction of the Doppler error.

For frequency measurement of simultaneously present frequencies

For greater clarity, it is briefly mentioned here how the presence of multiple frequencies at one time should be measured.

Samples of the signal to be assessed are continuously saved as memory values. A storage time can always be assigned to the memory values. The memory values are multiplied by a window signal. This can be one of the following window signals, for example: rectangular window, von Hann window, Hamming window, Blackman window, Blackman-Harris window, Blackman-Nuttall window, flat-top window, Bartlett window, Bartlett-Hann window, cosine window, Tukey window, Lanczos window, Kaiser window, Gaussian window. Other window types are conceivable. The window function has a reference time. The temporal length of the respective window should be less than the ultrasound burst duration (bd). Preferably, the temporal length of the respective window should be less than 1/10 of the ultrasound burst duration (bd). The memory values are multiplied by the window function for the respective reference time. In this process, a stored value is always multiplied by the value of the window signal to produce a windowed sample value whose time within the window signal corresponds to the sampling time of the stored value, taking the reference time into account. The windowed samples then produce a windowed signal that can be subjected to a Fourier transformation or a Z-transformation. If multiple frequencies are then evident in the transformed signal, then multiple frequencies are present in the signal at the reference time. The reference time is shifted, and the same analysis is repeated over and over again. This process is known as time-frequency analysis (TFA).

List of reference symbols

A

Ultrasound burst amplitude;

A1

first spectral ultrasonic burst amplitude of the first ultrasonic transducer (US1);

A2

second spectral ultrasonic burst amplitude of the second ultrasonic transducer (US2);

A3

third spectral ultrasonic burst amplitude of the third ultrasonic transducer (US3);

Amax1

first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f ₁ ). The first amplitude maximum (A _max1 ) of the sound radiation can be measured by exciting the first ultrasonic transducer (US1) with a first excitation frequency (f _A1 ), whereby the first excitation frequency (f _A1 ) is tuned and the first excitation frequency (f _A1 ) is determined at which the first ultrasonic transmitter (US1) absorbs the maximum active power. The sound power emitted in this way is understood in this document as the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1);

Amax2

second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonance frequency (f ₂ ). The second amplitude maximum (A _max2 ) of the sound radiation can be measured by exciting the second ultrasonic transducer (US2) with a second excitation frequency (f _A2 ), whereby the second excitation frequency (f _A2 ) is tuned and the second excitation frequency (f _A2 ) is determined at which the second ultrasonic transmitter (US2) absorbs the maximum active power. The sound power emitted in this way is understood in this document as the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2);

Amax3

third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonance frequency (f ₃ ). The third amplitude maximum (A _max3 ) of the sound radiation can be measured by exciting the third ultrasonic transducer (US3) with a third excitation frequency (f _A3 ), whereby the third excitation frequency (f _A3 ) is tuned and the third excitation frequency (f _A3 ) is determined at which the third ultrasonic transmitter (US3) absorbs the maximum effective power. The sound power emitted in this way is understood in this document as the third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3);

AS

control signal;

AS1

first control signal of the first ultrasonic transducer (US1);

AS2

first control signal of the second ultrasonic transducer (US2);

AS3

first control signal of the third ultrasonic transducer (US3);

AV

control device;

AV1

first control device of the first ultrasonic transducer (US1);

AV2

second control device of the second ultrasonic transducer (US2);

AV3

third control device of the third ultrasonic transducer (US3);

bd

Burst duration of an ultrasonic burst. The burst duration begins with the ultrasonic burst start (UBS) and ends with the ultrasonic burst end (UBE);

D

Object distance between the nearest relevant object and the ultrasonic measuring system;

Δf1

first bandwidth of the first ultrasonic transducer (US1). The first bandwidth is the first upper half-maximum amplitude frequency (f _1o ) at which the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonant frequency (f ₁ ), minus the first lower half-maximum amplitude frequency (f _1u ) at which the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is also half the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonant frequency (f ₁ );

Δf12

Frequency spacing between the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1) and the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2);

Δf2

second bandwidth of the second ultrasonic transducer (US2). The second bandwidth is the second upper half-maximum amplitude frequency (f _2o ) at which the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonant frequency (f ₂ ), minus the second lower half-maximum amplitude frequency (f _2u ) at which the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is also half the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonant frequency (f ₂ );

Δf23

Frequency spacing between the second resonance frequency (f ₂ ) of the second ultrasonic transducer (US2) and the third resonance frequency (f ₃ ) of the third ultrasonic transducer (US3);

Δf3

third bandwidth of the third ultrasonic transducer (US3). The third bandwidth is the third upper half-maximum amplitude frequency (f _3o ) at which the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half the third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonant frequency (f ₃ ), minus the third lower half-maximum amplitude frequency (f _3u ) at which the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is also half the third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonant frequency (f ₃ );

Δfg

Total frequency bandwidth of the ultrasonic sensor system (USS);

dmt12

second dual-mode time in 12 in which the first ultrasonic transducer (US1) and the second ultrasonic transducer (US2) emit sound;

dmt23

first dual-mode time in 12 in which the third ultrasonic transducer (US3) and the second ultrasonic transducer (US2) emit sound;

f1

first resonance frequency of the first ultrasonic transducer (US1). The first resonance frequency of the first ultrasonic transducer (US1) is determined within the meaning of this document such that the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) is sought by detuning the first excitation frequency (f _A1 ) of the first ultrasonic transducer (US1) with the excitation amplitude of the first excitation signal (AS1) of the first ultrasonic transducer (US1) preferably remaining locally constant at least over time. The first amplitude maximum (A _max1 ) can be measured by exciting the first ultrasonic transducer (US1) with a first excitation frequency (f _A1 ), wherein the first excitation frequency (f _A1 ) is tuned and the first excitation frequency (f _A1 ) is determined at which the first ultrasonic transmitter (US1) absorbs the maximum active power. The radiated sound power is defined in this document as the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1). The first excitation frequency (f _A1 ) at which this first amplitude maximum (A _max1 ) occurs is the first resonance frequency of the first ultrasonic transducer (US2);

f1/50%

first half-frequency. The first half-frequency is given by f _1/50% =(f _1s -f _1e )/2+f _1e ;

f1e

first final frequency;

f1m

first ultrasonic burst instantaneous frequency at which the first ultrasonic transmitter (US1) emits sound;

f1o

first upper half-maximum amplitude frequency (f _1o ). At the first upper half-maximum amplitude frequency (f _1o ), the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonant frequency (f ₁ ). The first upper half-maximum amplitude frequency (f _1o ) of the first ultrasonic transducer (US1) is above the first resonant frequency (f ₁ ) of the first ultrasonic transducer (US1);

f1s

first starting frequency;

f1u

first lower half-maximum amplitude frequency (f _1u ). At the first lower half-maximum amplitude frequency (f _1u ), the amplitude (A) of the sound radiation of the first ultrasonic transducer (US1) is half the first amplitude maximum (A _max1 ) of the sound radiation of the first ultrasonic transducer (US1) at its first resonance frequency (f ₁ ). The first lower half-maximum amplitude frequency (f _1u ) of the first ultrasonic transducer (US1) is below the first resonance frequency (f ₁ ) of the first ultrasonic transducer (US1);

f2

second resonance frequency of the second ultrasonic transducer (US2). The second resonance frequency of the second ultrasonic transducer (US2) is determined within the meaning of this document such that the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) is sought by detuning the second excitation frequency (f _A2 ) of the second ultrasonic transducer (US2) with the excitation amplitude of the second excitation signal of the second ultrasonic transducer (US2) preferably remaining locally constant at least over time. The second amplitude maximum (A _max2 ) can be measured by exciting the second ultrasonic transducer (US2) with a second excitation frequency (f _A2 ), wherein the second excitation frequency (f _A2 ) is tuned and the second excitation frequency (f _A2 ) is determined at which the second ultrasonic transmitter (US2) absorbs the maximum active power. The radiated sound power is referred to in this document as the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2). The second excitation frequency (f _A2 ) at which this second amplitude maximum (A _max2 ) occurs is the second resonance frequency of the second ultrasonic transducer (US2).

f2/50%

second half-frequency. The second half-frequency is given by f _2/50% =(f _2s -f _2e )/2+f _2e ;

f2e

second final frequency;

f2m

second ultrasonic burst instantaneous frequency at which the second ultrasonic transmitter (US2) emits sound;

f2o

second upper half-maximum amplitude frequency (f _2o ). At the second upper half-maximum amplitude frequency (f _2o ), the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonant frequency (f ₂ ). The second upper half-maximum amplitude frequency (f _2o ) of the second ultrasonic transducer (US2) is above the second resonant frequency (f ₂ ) of the second ultrasonic transducer (US2);

f2s

second starting frequency;

f2u

second lower half-maximum amplitude frequency (f _2u ). At the second lower half-maximum amplitude frequency (f _2u ), the amplitude (A) of the sound radiation of the second ultrasonic transducer (US2) is half the second amplitude maximum (A _max2 ) of the sound radiation of the second ultrasonic transducer (US2) at its second resonant frequency (f ₂ ). The second lower half-maximum amplitude frequency (f _2u ) of the second ultrasonic transducer (US2) is below the second resonant frequency (f ₂ ) of the second ultrasonic transducer (US2);

f3

third resonance frequency of the third ultrasonic transducer (US3). The third resonance frequency of the third ultrasonic transducer (US3) is determined within the meaning of this document such that the third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) is sought by detuning the third excitation frequency (f _A3 ) of the third ultrasonic transducer (US3) with the excitation amplitude of the third excitation signal of the third ultrasonic transducer (US3) preferably remaining at least locally constant over time. The third amplitude maximum (A _max3 ) can be measured by exciting the third ultrasonic transducer (US3) with a third excitation frequency (f _A3 ), wherein the third excitation frequency (f _A3 ) is tuned and the third excitation frequency (f _A3 ) is determined at which the third ultrasonic transmitter (US3) absorbs the maximum active power. The radiated sound power is defined in this document as the third amplitude maximum (A _max3 ) of the sound radiation of the first ultrasonic transducer (US1). The third excitation frequency (f _A3 ) at which this third amplitude maximum (A _max3 ) occurs is the third resonance frequency of the third ultrasonic transducer (US3);

f3/50%

third half-frequency. The third half-frequency is given by f _3/50% =(f _3s -f _3e )/2+f _3e ;

f3e

third final frequency;

f3m

third ultrasonic burst instantaneous frequency at which the third ultrasonic transmitter (US3) emits sound;

f3o

third upper half-maximum amplitude frequency (f _3o ). At the third upper half-maximum amplitude frequency (f _3o ), the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half the third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonant frequency (f ₃ ). The third upper half-maximum amplitude frequency (f _3o ) of the third ultrasonic transducer (US3) is above the third resonant frequency (f ₃ ) of the third ultrasonic transducer (US3);

f3s

third starting frequency;

f3u

third lower half-maximum amplitude frequency (f _3u ). At the third lower half-maximum amplitude frequency (f _3u ), the amplitude (A) of the sound radiation of the third ultrasonic transducer (US3) is half the third amplitude maximum (A _max3 ) of the sound radiation of the third ultrasonic transducer (US3) at its third resonant frequency (f ₃ ). The third lower half-maximum amplitude frequency (f _3u ) of the third ultrasonic transducer (US3) is below the third resonant frequency (f ₃ ) of the third ultrasonic transducer (US3);

fa

Control instantaneous frequency;

fA1

first control frequency of the first ultrasonic transducer (US1);

fA1/50%

first half-frequency control frequency;

fA1e

first final control frequency;

fA1s

first start control frequency;

fA2

second control frequency of the second ultrasonic transducer (US2);

fA2/50%

second half-frequency control frequency;

fA2e

second final control frequency;

fA2s

second start control frequency;

fA3

third control frequency of the third ultrasonic transducer (US3);

fA3/50%

third half-frequency control frequency;

fA3e

third final control frequency;

fA3s

third start control frequency;

fm

Ultrasonic burst instantaneous frequency;

fm,0

zeroth ultrasonic instantaneous frequency of the zeroth ultrasonic pulse (P ₀ ) in the zeroth ultrasonic period with the zeroth ultrasonic period duration (T ₀ ) within an ultrasonic burst (UB);

fm,1

first ultrasonic instantaneous frequency of the first ultrasonic pulse (P ₁ ) in the first ultrasonic period with the first ultrasonic period duration (T ₁ ) within an ultrasonic burst (UB);

fm,2

second ultrasonic instantaneous frequency of the second ultrasonic pulse (P ₂ ) in the second ultrasonic period with the second ultrasonic period duration (T ₂ ) within an ultrasonic burst (UB);

fm,3

third ultrasonic instantaneous frequency of the third ultrasonic pulse (P ₃ ) in the third ultrasonic period with the third ultrasonic period duration (T ₃ ) within an ultrasonic burst (UB);

fm,4

fourth ultrasonic instantaneous frequency of the fourth ultrasonic pulse (P ₄ ) in the fourth ultrasonic period with the fourth ultrasonic period duration (T ₄ ) within an ultrasonic burst (UB);

fm,5

fifth ultrasonic instantaneous frequency of the fifth ultrasonic pulse (P ₅ ) in the fifth ultrasonic period with the fifth ultrasonic period duration (T ₅ ) within an ultrasonic burst (UB);

fm,6

sixth ultrasonic instantaneous frequency of the sixth ultrasonic pulse (P ₆ ) in the sixth ultrasonic period with the sixth ultrasonic period duration (T ₆ ) within an ultrasonic burst (UB);

fm,7

seventh ultrasonic instantaneous frequency of the seventh ultrasonic pulse (P ₇ ) in the seventh ultrasonic period with the seventh ultrasonic period duration (T ₇ ) within an ultrasonic burst (UB);

fm,j

j-th ultrasonic instantaneous frequency of the j-th ultrasonic pulse (P _j ) in the j-th ultrasonic period with the j-th ultrasonic period duration (T _j ) within an ultrasonic burst (UB) (here j stands for a positive integer);

O

Object;

O1

first object;

O2

second object;

P0

zeroth ultrasonic pulse in the zeroth ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P1

first ultrasonic pulse in the first ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P2

second ultrasonic pulse in the second ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P3

third ultrasonic pulse in the third ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P4

fourth ultrasonic pulse in the fourth ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P5

fifth ultrasonic pulse in the fifth ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P6

sixth ultrasonic pulse in the sixth ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

P7

seventh ultrasonic pulse in the seventh ultrasonic period of the exemplary ultrasonic burst (UB) of the 2a ;

Pj

j-th ultrasonic pulse in the j-th ultrasonic period of the exemplary ultrasonic burst (UB) (here j stands for a positive integer);

SF1

first frequency curve of the ultrasonic burst instantaneous frequency (f _m ) or the first ultrasonic burst instantaneous frequency (f _m1 ) of a first ultrasonic subburst within an ultrasonic burst (UB);

SF2

second frequency curve of the second ultrasonic burst instantaneous frequency (f _m2 ) of a second ultrasonic subburst within an ultrasonic burst (UB). Within the ultrasonic burst (UB), this second ultrasonic subburst is typically superimposed on the first ultrasonic subburst, preferably by summation;

SF3

third frequency curve of the third ultrasonic burst instantaneous frequency (f _m3 ) of a third ultrasonic subburst within an ultrasonic burst (UB). Within the ultrasonic burst (UB), this third ultrasonic subburst is typically superimposed on the first ultrasonic subburst and the second ultrasonic subburst, preferably by summation;

s1

first distance of the first ultrasonic sensor system (USS1) from the object (O)

s2

second distance of the second ultrasonic sensor system (USS2) from the object (O)

smt1

first single-mode era;

smt2

second single-mode time;

smt3

third single-mode time;

USA

Ultrasound system axis;

USS

Ultrasonic sensor system;

USS1

first ultrasonic sensor system;

USS2

second ultrasonic sensor system;

t

Time;

t1/50%

First half-frequency time point. At this first half-frequency time point (t _1/50% ), the first ultrasound transducer (US1) transmits at a first half-frequency (f _1/50% );

t1a

first temporal burst phase;

t1b

second temporal burst phase;

t1s

first broadcast start time;

t1e

first broadcast end time;

t2/50%

second half-frequency time point. At this second half-frequency time point (t _2/50% ), the second ultrasound transducer (US2) transmits at a second half-frequency (f _2/50% ).

t2s

second broadcast start time;

t2e

second transmission end time;

t3/50%

Third half-frequency time point. At this third half-frequency time point (t _3.50% ), the third ultrasound transducer (US3) transmits at a second half-frequency (f _3/50% ).

t3s

third broadcast start time;

t3e

third broadcast end time;

T0

zeroth ultrasonic period duration of the zeroth ultrasonic period of the zeroth ultrasonic pulse (P ₀ );

T1

first ultrasonic period duration of the first ultrasonic period of the first ultrasonic pulse (P ₁ );

T2

second ultrasonic period duration of the second ultrasonic period of the second ultrasonic pulse (P ₂ );

T3

third ultrasonic period duration of the third ultrasonic period of the third ultrasonic pulse (P ₃ );

T4

fourth ultrasonic period duration of the fourth ultrasonic period of the fourth ultrasonic pulse (P ₄ );

T5

fifth ultrasonic period duration of the fifth ultrasonic period of the fifth ultrasonic pulse (P ₅ );

T6

sixth ultrasonic period duration of the sixth ultrasonic period of the sixth ultrasonic pulse (P ₆ );

T7

seventh ultrasound period duration of the seventh ultrasound period of the seventh ultrasound pulse (P ₇ );

Tj

j-th ultrasonic period duration of the j-th ultrasonic period of the j-th ultrasonic pulse (P _j ) (here j stands for a positive integer);

UB

Ultrasonic burst;

UBS

Ultrasonic burst start;

UBE

Ultrasonic burst end

US1

first ultrasound transducer;

US2

second ultrasound transducer;

US3

third ultrasound transducer;

USS

Ultrasonic sensor system;

USS1

first ultrasonic sensor system;

USS2

second ultrasonic sensor system;

vf

Frequency change rate of the ultrasonic burst instantaneous frequency (f _m ) over time (t);

Claims (6)

A method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps of: - Step 1: emitting an ultrasonic burst with an ultrasonic burst duration (bd) that does not exceed a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS); - Step 2: receiving an ultrasonic burst reflected by an object (O); - Step 3: determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst; - Step 4: Repeating steps 1 to 4, the ultrasonic burst duration (bd) depending on the determined distance (D, s1, s2), characterized in that - the number of ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) and the associated number of frequency curves (SF1, SF2, SF3) of these ultrasonic burst instantaneous frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic burst (UB) depends on the distance (D). Procedure according to Claim 1 , - where the ultrasonic burst length of the ultrasonic burst duration (bd) is increased by the fourth root of the determined distance (D). Procedure according to Claim 1 and/or 2 - wherein the amplitude (A) of the emitted ultrasonic burst depends essentially proportionally to (D+D ₀ ) ^1/k , with 2≤k≤5 or preferably k=2 or k=4, on the determined distance (D), where D ₀ is a constant which can be zero. Method according to one or more of the Claims 1 until 3 - wherein at least several ultrasonic bursts (UB) are emitted at a temporal ultrasonic burst interval and - wherein the first temporal ultrasonic burst interval is the temporal interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst - wherein the second temporal ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the third ultrasonic burst immediately following this second ultrasonic burst depends on the determined distance (D). Method according to one or more of the Claims 1 until 4 - whereby the temporal ultrasonic burst spacing of the ultrasonic bursts becomes shorter with decreasing spatial distance (D) between the ultrasonic sensor system and the object (O). Procedure according to Claim 5 - wherein the temporal ultrasonic burst spacing of the ultrasonic bursts becomes shorter by a time 2*l/c with c as the speed of sound with a tolerance of +/- 25% and/or with a tolerance of +/- 10% and/or with a tolerance of +/- 5% when the spatial distance (D) between the ultrasonic sensor system and the object (O) is shortened by a length l.