WO2018120335A1 - Capacitive sensor for absolute angular displacement measurement - Google Patents

Abstract

A capacitive sensor for absolute angular displacement measurement, characterized in that the capacitive sensor for absolute angular displacement measurement comprises a sensitive structure (1), a signal modulation-demodulation circuit (2) and an error compensation and fusion module (3); the sensitive structure (1) comprises a first stator (11), a rotor (12) and a second stator (13) which are longitudinally provided in parallel; an accurate measurement collecting electrode (111) is provided at the outer side of the top portion of the first stator (11), and an accurate measurement exciting electrode (112) is provided at the inner side of the top portion of the first stator (11); an accurate measurement sensitive electrode (121) is provided at the outer side of the bottom portion of the rotor (12), an accurate measurement coupling electrode (122) is provided at the inner side of the bottom portion of the rotor (12), a rough measurement sensitive electrode (123) is provided at the outer side of the top portion of the rotor (12), a rough measurement coupling electrode (124) is provided at the inner side of the top portion of the rotor (12), the accurate/and rough measurement sensitive electrodes (121, 123) and the accurate/and rough measurement coupling electrodes (122, 124) are equipotential bodies; a rough measurement collecting electrode (131) is provided at the outer side of the bottom portion of the second stator (13), and a rough measurement exciting electrode (132) is provided at the inner side of the bottom portion of the second stator (13); the signal modulation-demodulation circuit (2) is used for measuring accurate angular displacement and rough angular displacement; the error compensation and fusion module (3) is used for calculating absolute angular displacement after error compensation. The invention can be widely used in sensors for angular displacement measurement.

Description

Absolute capacitance angular displacement measuring sensor Technical field

The invention relates to an angular displacement sensor, in particular to an absolute capacitance angular displacement measuring sensor, belonging to the field of angular displacement sensors.

Background technique

The angular displacement sensor is a displacement sensor that converts physical quantities such as rotational angular position and angular displacement into electrical signals. It is a sensor used to detect angle, velocity, length, displacement and acceleration in the field of automation. Its application is large to CNC machine tools and robots. The position detection and transmission speed control of packaging machinery, printing machinery, elevators, factory automation related equipment, and the measurement and control of the amount of rotation of office automation equipment such as disks and printers have become an indispensable part of various fields.

At present, there are a variety of rotary angular displacement sensors available on the market. According to the principle of detection, optical encoders and magnetic encoders can be classified. Among them, optical rotary encoders are used more, magnetic encoders are second, and existing angular displacement measurements are available. The sensor has high precision, but it has the disadvantages of large volume, complicated processing, high cost, harsh environment requirements and poor dynamic characteristics. For example, the magnetic encoder is complicated to process, high in cost, heavy in weight and sensitive to electromagnetic environment. The lower capacitive angular displacement sensor has high stability and can be used for non-contact measurement, dynamic response and adapt to harsh environments. It has been recognized by more and more people as the most promising sensor.

At home and abroad, there are many researches on the measurement of angular displacement of capacitive sensors. It has also made great breakthroughs, mainly focusing on the improvement of sensitive structures. The conventional sensitive structure is fan-shaped and split-type, and the ability to acquire diagonal displacement information is limited. Sensitivity is also limited by processing accuracy, and the demodulation circuit is complex, and absolute angular position measurement cannot be achieved. Most capacitive angular displacement sensors can only be used for relative measurement and have a limited dynamic range.

Summary of the invention

In view of the above problems, an object of the present invention is to provide an absolute capacitance angular displacement measuring sensor with high precision, high sensitivity, high adaptability and low cost.

To achieve the above object, the present invention adopts the following technical solution: an absolute capacitance angular displacement measuring sensor, wherein the angular displacement measuring sensor comprises a sensitive structure, a signal modulation and demodulation circuit, an error compensation and fusion module, and a power module; The sensitive structure includes a stator and a rotor, the stator includes a first stator and a second stator, the first stator, the rotor and the second stator are sequentially disposed in parallel in a longitudinal direction; the first stator includes a precision measuring electrode Qualifying the excitation electrode and the first charge amplifier, the first stator is fixedly disposed on the bottom of the first stator, and the fine measurement acquisition electrode is disposed outside the first stator top, the first stator top The fine excitation electrode is disposed on the inner side; the rotor includes a precision sensing electrode, a precision coupling electrode, and a coarse electrode Detecting a sensitive electrode and a coarse measuring coupling electrode, the rotor is fixedly connected to the moving member through a main shaft, the fine sensing sensitive electrode is disposed outside the bottom of the rotor, the fine measuring coupling electrode is disposed inside the bottom of the rotor, and the fine measuring is performed The sensitive electrode and the precision measuring coupling electrode are equipotential bodies; the rough sensing sensitive electrode is disposed outside the top of the rotor, the coarse measuring coupling electrode is disposed inside the top of the rotor, and the coarse sensing sensitive electrode and the coarse measuring coupling electrode are An equal potential body; the second stator includes a coarse measurement acquisition electrode, a coarse measurement excitation electrode, and a second charge amplifier, wherein the second stator top is fixedly disposed with the second charge amplifier, and the second stator bottom is disposed outside The coarse measurement acquisition electrode is disposed on the inner side of the bottom of the second stator; the fine measurement acquisition electrode and the precision measurement electrode are directly opposite to form a precision measurement capacitance, and the precision measurement excitation electrode and the fine measurement coupling The electrode is facing oppositely to form a precision measurement coupling capacitor, and the coarse measurement acquisition electrode and the coarse measurement sensitive electrode are opposite to form a rough measurement measurement capacitance, and the coarse measurement excitation electrode and the coarse measurement coupling current Forming a coarse measurement coupling capacitor; the signal modulation and demodulation circuit includes a fine measurement/and coarse measurement cyclode demodulation module and a fine measurement/and coarse measurement angle signal modulation module, and the fine measurement/and coarse measurement rotational solution The modulation module processes the output carrier signal to the fine/and coarse measurement excitation electrodes and acts on the fine measurement/and coarse measurement coupling electrodes through the fine measurement/and coarse measurement coupling capacitance, the fine measurement/ And the coarse-measurement coupling electrode transmits the carrier signal to the fine/measured sensitive electrode, and the fine measurement/and coarse measurement is performed by the fine measurement/and the coarse measurement measurement capacitance to the fine measurement/and coarse measurement acquisition electrode. The capacitance signal, the fine measurement/and the coarse capacitance measurement signal are obtained through the corresponding charge amplifier and the fine measurement/and coarse measurement angle modulation module to obtain the fine measurement/and coarse measurement orthogonal rotation signal, and then the fine measurement/and coarse measurement rotation The demodulation module solves the refined/and coarse angular displacement; the error compensation and fusion module is used for error compensation of the fine angular displacement and the coarse angular displacement, and the compensated fine angular displacement and coarse angle The displacement is calculated by the absolute displacement; the power module is used for each part Power supply.

An absolute capacitance angular displacement measuring sensor, characterized in that the angular displacement measuring sensor comprises a sensitive structure, a signal modulation and demodulation circuit, an error compensation and fusion module and a power module; the sensitive structure comprises a stator and a rotor, and the The stator and the rotor are arranged in parallel; the stator comprises a fine measuring collecting electrode, an excitation electrode, a rough measuring collecting electrode and a charge amplifier, wherein the charge amplifier is fixedly arranged on the bottom of the stator, and the top of the stator is arranged in order from the outside to the inside. Measuring the collecting electrode, the exciting electrode and the rough measuring collecting electrode; the rotor comprises a fine sensing sensitive electrode, a coupling electrode and a coarse sensing sensitive electrode; the bottom of the rotor is arranged with the fine sensing sensitive electrode, the coupling electrode and the thick from the outside to the inside Sensing the sensitive electrode, the rotor is fixedly connected to the moving piece through the main shaft; the fine measuring collecting electrode and the fine measuring sensitive electrode are facing each other to form a fine measuring capacitance, and the excitation electrode and the coupling electrode are facing each other to form a coupling capacitance, and the rough measuring The collecting electrode and the rough sensing sensitive electrode are facing each other to form a rough measuring capacitance; the signal modulation and demodulation circuit includes a measurement/and coarse measurement cyclone demodulation module and a fine measurement/and coarse measurement rotation angle signal modulation module, wherein the fine measurement/and coarse measurement cyclone demodulation module processes the output carrier signal to the excitation electrode and Acting on the coupling electrode by a coupling capacitor that transmits a carrier signal to the fine/measured sensitive electrode and acts on the fine/and coarse measurement by means of a fine/and coarse measurement capacitance Acquisition electrode The fine measurement/and coarse measurement capacitance signal is obtained, and the fine measurement/and coarse measurement capacitance signal is obtained through the corresponding charge amplifier and the fine measurement/and coarse measurement angle modulation module to obtain the fine measurement/and coarse measurement orthogonal rotation signal. The measurement/and coarse measurement and demodulation module are solved to obtain the fine measurement/and coarse measurement angular displacement; the error compensation and fusion module is used for error compensation of the precision angular displacement and the coarse angular displacement, and the compensated fine The angular displacement and the coarse angular displacement are calculated by the absolute displacement; the power module is used to supply power to each component.

Further, the signal modulation and demodulation circuit further includes a fine measurement carrier signal conditioning module and a coarse measurement carrier signal conditioning module; the fine measurement carrier signal conditioning module is configured to output a carrier signal to the fine measurement and demodulation module Performing conditioning; the coarse measurement carrier signal conditioning module is configured to perform conditioning on a carrier signal output by the coarse measurement and demodulation module.

Further, the change of the rotation angle of the stator and the rotor is converted into a four-way precision measurement capacitance signal by the precision measurement capacitance, and the specific process is: the fine sensing sensitive electrode is a function

And function

a ring-shaped petal structure region, wherein R represents a polar circle radius of the petal-like precision sensing electrode, τ represents a half of the width of the fine sensing electrode, and N represents a sine included in the precision sensing electrode The number of cycles,

Denoting a mechanical rotation angle of the rotor and the stator; dividing the oppositely-shaped fine measuring acquisition electrode into a sector-shaped region at intervals of 90° in a sinusoidal period of the precision sensing electrode, and dividing into a sector within a sinusoidal period The four sectoral regions are denoted as S ₀ , S ₉₀ , S ₁₈₀ and S ₂₇₀ , respectively, and the four sector regions are divided into eight sector regions by the inner and outer circles of radius R, respectively:

Where θ represents the measured output angle and has a relationship:

The _outer region connecting _the region S ₀ S _180, S ₉₀ are connected _{in the} region _{outside the} region S _270, S _{180 in the} region _outside the connection area S ₀ and _the area S ₉₀ S ₂₇₀ connected to _{an outer} area of the obtained fine sensing electrodes and sensitive Fine The four facing areas of the facing area of the collecting electrode that vary with the angle of rotation are expressed as:

Wherein A represents the DC component of the facing area, and B represents the amplitude determined by the parameters R, τ; and the four facing regions formed by the fine sensing sensitive electrode and the fine measuring collecting electrode in each sinusoidal period are respectively connected:

A multi-stage capacitor formed by four facing regions within one sinusoidal period is denoted as C ₁ , C ₂ , C ₃ and C ₄ , respectively, and a multi-stage capacitor C ₁ of N sinusoidal periods in the precision sensing electrode C ₂ , C ₃ and C ₄ are connected to obtain four precision measurement capacitor signals C _N1 , C _N2 , C _N3 and C _N4 .

Further, the four-way precision capacitance signal is obtained by the corresponding charge amplifier and the fine-precision cyclode demodulation module to obtain two-way precision orthogonal transformation signals, and then the calculated angular displacement is calculated. The specific process is: four-way precision measurement. The four precision measured charge signals obtained by the capacitor signal passing through the corresponding charge amplifier are respectively expressed as:

Wherein w represents the frequency at which the fine-tuning resolver demodulation module outputs a sinusoidal excitation signal, sin(wt) represents a carrier signal acting on the fine excitation electrode, and d represents a spacing between the stator and the rotor; The road fine charge signal is obtained by the fine angle signal modulation module to obtain two precision orthogonal polarization signals, which are respectively represented as:

U _{fine sin} =Usin(wt)sin(θ)

U _{fine cos} = Usin(wt)cos(θ)

The obtained two-way fine orthogonal vibration signal is solved by the fine-precision cyclode demodulation module to obtain the refined angular displacement θ _fine .

Further, the change of the rotation angle of the stator and the rotor is converted into two coarse-orthogonal orthogonal rotation signals by the coarse measurement capacitance, the corresponding charge amplifier, and the coarse-measurement demodulation module, thereby calculating the coarse angular displacement. The specific process is: the rough sensing sensitive electrode is an eccentric ring with an eccentricity d, and the ring-shaped coarse measuring collecting electrode is divided into a sector-shaped area every 90°, and the four sector-shaped areas are further divided by a circle with a radius of R. into eight fan-shaped area, are represented by S _{'the 0,} S' _{within 90,} S _{'within 180 [,} S' _{within 270,} S _{'0, the} S' _{90, the} S 'and _{outer 180 [S' 270, but} the The area S' _{0 is outside the} connection area S' ₁₈₀ , the area S' _{90 is outside the} connection area S' ₂₇₀ , the area S' _{180 is outside the} connection area S' _0, and the area S' _{270 is outside the} connection area S' _90. The four pairs of positive facing areas of the coarse sensing sensitive electrode and the coarse measuring collecting electrode vary with the rotation angle; the multi-level capacitance formed by the four facing regions in one sinusoidal period is denoted as C ₅ , C ₆ , C _{7 respectively} and C _8; corresponding to the charge amplifier coarse acquisition collected four electrodes Coarse capacitance signal into four coarse charge signals, and converts the rotational angle detected by the coarse signal conditioning module two orthogonal coarse resolver signal, wherein:

_{The crude} U _{sin = Usin (wt) sin (} θ)

U _{coarse cos} = Usin(wt)cos(θ)

The obtained two-way coarse-measurement orthogonal rotatory signal is solved by the coarse-measurement variable-rotation demodulation module to obtain a coarse angular displacement θ _coarse .

Further, the error compensation and fusion module includes a fine measurement/and coarse measurement error compensation module; the fine measurement/and coarse measurement error compensation module performs error compensation on the fine measurement/and coarse measurement angular displacement, and the compensated precision The measured/and coarse angular displacement is calculated by the absolute displacement. The specific process is: respectively determine the error type of the fine measurement and the coarse measurement, the error type includes the harmonic component error, the signal amplitude error and the noise error; and according to the error type, The acquired data is identified by data, and the error compensation parameters of the fine measurement and the coarse measurement are calculated; the fine measurement/and the coarse angular displacement are obtained; and the compensation function is generated according to the obtained error compensation parameter and the fine measurement/and coarse measurement angular displacement. The correction value and the coarse angle measurement are respectively corrected by the compensation function to obtain the correction value of the fine measurement/and the coarse angular displacement; the refined angular displacement is calculated according to the formula θ _{R fine} n*θ _R The number of divisions of the coarse angular displacement is n; the absolute angular displacement θ _is calculated according to the formula θ _real = n * θ _R.

The invention adopts the above technical solutions, and has the following six advantages: 1. The invention realizes the displacement measurement based on the spin-on demodulation technology, and can be easier under the single excitation effect compared with the existing non-contact capacitive displacement sensor. Achieve high precision and large range measurements. 2. The invention obtains the precision angular displacement and the coarse angular displacement by two-way measurement, and then obtains absolute displacement after error correction by error compensation and fusion module, which has good sensitivity, robustness, dynamic characteristics and fault tolerance. 3. The invention realizes time division multiplexing of the signal modulation and demodulation circuit through the setting of the switch, has the advantages of simple structure, small size and low cost, and can be widely applied to the angular displacement measuring sensor.

DRAWINGS

Figure 1 is a schematic view of the principle of the present invention;

Figure 2 is a schematic structural view of Embodiment 1 of the present invention;

3 is a schematic view showing an electrode distribution of a first stator in Embodiment 1 of the present invention;

Figure 4 is a schematic cross-sectional view of Figure 2;

Figure 5 is a schematic view showing the distribution of electrodes at the bottom of the rotor in Embodiment 1 of the present invention;

Figure 6 is a schematic view showing the distribution of electrodes at the top of the rotor in Embodiment 1 of the present invention;

7 is a schematic view showing an electrode distribution of a second stator in Embodiment 1 of the present invention;

Figure 8 is a waveform diagram of the SIN function of the fine measurement signal or the coarse measurement signal output in the present invention;

Figure 9 is a waveform diagram of a COS function of the fine measurement signal or the coarse measurement signal output in the present invention;

Figure 10 is a waveform diagram of the fine measurement envelope signal and the coarse measurement envelope signal output by the present invention;

11 is a schematic flow chart of an error compensation and fusion module in the present invention;

Figure 12 is a schematic diagram of an error compensation function in the present invention;

13 is a schematic diagram of an angle output effect after error compensation in the present invention;

Figure 14 is a schematic structural view of Embodiment 2 of the present invention;

Figure 15 is a cross-sectional structural view of Figure 14;

Figure 16 is a schematic view showing the electrode distribution of the stator in the second embodiment of the present invention;

Figure 17 is a schematic view showing the electrode distribution of the rotor in the second embodiment of the present invention.

detailed description

The invention is described in detail below with reference to the accompanying drawings. It is to be understood, however, that the appended claims In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for the purpose of description only and are not to be construed as indicating or implying relative importance.

Example 1:

As shown in FIG. 1, the absolute capacitance angular displacement measuring sensor of the present invention comprises a sensitive structure 1, a signal modulation and demodulation circuit 2, and an error compensation and fusion module 3.

As shown in FIG. 2, the sensitive structure 1 includes a first stator 11, a rotor 12, and a second stator 13, and the annular first stator 11, the annular rotor 12, and the annular second stator 13 are the same in shape and are longitudinally arranged in parallel.

As shown in FIG. 3, the first stator 11 includes a fine measurement collecting electrode 111, a fine excitation electrode 112 and a first charge amplifier (not shown); a first charge amplifier is fixedly disposed at the bottom of the first stator 11 An annular fine measurement collecting electrode 111 is disposed on the outer side of the top of the stator 11, and a ring-shaped fine excitation electrode 112 is disposed on the inner side of the top of the first stator 11.

As shown in FIGS. 4-6, the rotor 12 includes a precision sensing electrode 121, a precision coupling electrode 122, a coarse sensing electrode 123, and a coarse coupling electrode 124. The rotor 12 is fixedly coupled to the moving member through the main shaft 125, and the rotor 12 is disposed outside the bottom of the rotor 12. The petal structure fine-measures the sensitive electrode 121, and the ring-shaped precision measuring coupling electrode 122 is disposed on the inner side of the bottom of the rotor 12, and the fine-sensing sensitive electrode 121 and the fine-measuring coupling electrode 122 are equipotential bodies; an eccentric circular-shaped rough sensing sensitive electrode is disposed on the outer side of the rotor 12 123. A ring-shaped coarse-coupling coupling electrode 124 is disposed on the inner side of the top of the rotor 12, and the coarse sensing-sensitive electrode 123 and the coarse-measuring coupling electrode 124 are equipotential bodies.

As shown in FIG. 7, the second stator 13 includes a coarse measurement acquisition electrode 131, a coarse measurement excitation electrode 132, and a second charge amplifier (not shown); a second charge amplifier is fixedly disposed on the top of the second stator 13, and the second stator The annular rough measurement acquisition electrode 131 is disposed on the outer side of the bottom of the bottom portion of the bottom of the second stator 12, and the annular rough measurement excitation electrode 132 is disposed on the inner side of the bottom of the second stator 12; the fine measurement acquisition electrode 111 and the fine measurement sensitive electrode 121 are oppositely formed to form the measurement capacitance, and the excitation electrode 112 is finely measured. The precision measuring coupling electrode 122 forms a precision measuring coupling capacitor, the coarse measuring collecting electrode 131 and the coarse sensing sensitive electrode 123 form a rough measuring capacitance, and the rough measuring excitation electrode 132 and the coarse measuring coupling electrode 124 form a coarse measuring coupling capacitor. .

The signal modulation and demodulation circuit 2 includes a fine measurement and demodulation module 21, a fine carrier signal conditioning module 22, a fine angle signal modulation module 23, a coarse measurement and demodulation module 24, a coarse measurement carrier signal conditioning module 25, and a coarse The rotation angle signal modulation module 26; the error compensation and fusion module 3 includes a fine measurement error compensation module 31, a coarse measurement error compensation module 32, a main processor module 33, and a power module 34.

The precision measurement and demodulation module 21 applies the output carrier signal to the fine measurement excitation electrode 112 via the fine measurement carrier signal conditioning module 22, and then acts on the fine measurement coupling electrode 122 through the fine measurement coupling capacitance, and the precision measurement coupling electrode 122 transmits the carrier signal. It is transmitted to the fine sensing electrode 121, and the four-way precision measuring capacitance signal is obtained by the fine measuring and measuring capacitance applied to the fine measuring collecting electrode 111 (this is not limited thereto, and can be determined according to actual needs), and the four-way fine measuring is performed. The capacitor signal is converted into a four-way fine-charged charge signal by the first charge amplifier, and two precise precision orthogonally-rotated signals are obtained by the fine-angle measurement signal modulation module 23, and then refined by the fine-precision cyclode demodulation module 21 to obtain a fine measurement. Angular displacement.

At the same time, the coarse measurement and demodulation module 24 applies the output carrier signal to the coarse measurement excitation electrode 132 via the coarse measurement carrier signal conditioning module 25, and then acts on the coarse measurement coupling electrode 124 through the coarse measurement coupling capacitance, and the coarse measurement coupling electrode 124 will The carrier signal is transmitted to the coarse sensing sensitive electrode 123, and the four-way coarse measuring capacitance signal is obtained by the coarse measuring capacitance applied to the coarse measuring collecting electrode 131, and the four-way coarse measuring capacitance signal is converted into four rough measured charging signals by the second charging amplifier. And obtaining the coarse coarse-rotation signal by the coarse-measurement angle modulation module 26, and then calculating the coarse angular displacement by the coarse-measurement demodulation module 24.

The precision angular displacement is compensated by the fine error compensation module 31, and the coarse angular displacement is compensated by the coarse error compensation module 32. The compensated fine angular displacement and the coarse lateral angular displacement are calculated by the existing fusion algorithm. The absolute angular displacement is sent to the main processor module 33, which is used to power the absolute capacitive angular displacement measuring sensor of the present invention.

In a preferred embodiment, the fine sensing electrode 121 is a function

And function

a ring-shaped annular petal structure region, wherein R represents a polar circle radius of the petal-like precision measuring electrode 121 (ie, an inner and outer divided circle radius of the fine measuring electrode 111), and τ represents a half of the width of the fine sensing electrode 121, N Representing the number of sinusoidal periods included in the precision sensing electrode 121,

Representing the mechanical rotation angle of the rotor and the first stator; in a sinusoidal period of the precision sensing electrode 121, the right fine measurement collecting electrode 111 is divided into a sector area every 90° apart, and four are divided into one sinusoidal period. The fan-shaped areas are denoted as S ₀ , S ₉₀ , S ₁₈₀ and S ₂₇₀ , respectively, and the four sector-shaped areas are further divided into eight sector-shaped areas by the inside and outside of the circle of radius R, which are respectively expressed as:

Where θ represents the measured output angle and has a relationship:

The area S _{0 is outside the} connection area S ₁₈₀ , the area S _{90 is outside the} connection area S ₂₇₀ , the area S _{180 is outside the} connection area S ₀ and the area S _{270 is outside the} connection area S ₉₀ (ie, the different color areas in FIG. 3) The four positively-oriented regions obtained by respectively connecting the corresponding areas of the fine sensing sensitive electrode 121 and the fine measuring collecting electrode 111 with the rotation angle are respectively represented as:

Wherein, A represents a direct current component of the facing area, and B represents an amplitude determined by the parameters R, τ; and the four positive facing regions formed by the fine sensing sensitive electrode 121 and the fine measuring collecting electrode 111 in each sinusoidal period are respectively connected to each other:

The multi-stage capacitors formed by the four facing regions in one sinusoidal period are denoted as C ₁ , C ₂ , C ₃ and C ₄ , respectively, and the multi-stage capacitor C ₁ of N sinusoidal periods in the sensitive electrode 121 is finely measured, C ₂ , C ₃ and C ₄ are respectively connected to obtain four-way precision capacitance signals C _N1 , C _N2 , C _N3 and C _N4 . At this time, the rotation angle change of the first stator 11 and the rotor 12 is converted into four-way fine measurement. Capacitance signal.

In a preferred embodiment, the four precision charge signals obtained after the four precision capacitance signals pass through the first charge amplifier are respectively expressed as:

Wherein w represents the frequency at which the precision varistor demodulation module 21 outputs the sinusoidal excitation signal, sin(wt) represents the carrier signal acting on the fine excitation electrode 112, and d represents the spacing between the first stator 11 and the rotor 12.

As shown in FIG. 8 to FIG. 9 , the two-way fine-accurate orthogonal variable-rotation signals obtained by the four-way fine-measurement charge signal through the fine-angle measurement signal modulation module 23 are as follows:

U _{fine sin} =Usin(wt)sin(θ)

U _{fine cos} = Usin(wt)cos(θ)

The obtained two-way fine orthogonal vibration signal is solved by the precision measurement and vibration demodulation module 21 to obtain the refined angular displacement θ _fine .

In a preferred embodiment, the coarse sensing electrode 123 is an eccentric ring with an eccentricity d, and the annular rough measurement collecting electrode 131 is divided into a sector by 90° intervals, and the four sector regions are further rounded by a radius R. is divided into eight fan-shaped areas inside and outside, are represented by S _{'the 0,} S' _{within 90,} S _{'within 180 [,} S' _{within 270,} S _{'outside 0,} S' _{90 outer,} S 'and _{outer 180 [S' 270 outer} , the _outer region S _{'within 0} connection region S' _180, the region S _'90 connection region S' _{270, the} area S _'180 connector region S' _{0 outside} and a region S _'270 connector region S' _{90 outer} obtained The four pairs of positively facing areas of the rough sensing sensitive electrode 123 and the coarse measuring collecting electrode 131 vary with the angle of rotation; the multi-level capacitors formed by the four facing regions in one sinusoidal period are denoted as C ₅ , C ₆ , respectively C ₇ and C ₈ , at this time, the change of the rotation angle of the rotor 12 and the second stator 13 is converted into a four-way coarse capacitance signal; the second charge amplifier 133 converts the four-way coarse capacitance signal collected by the coarse measurement acquisition electrode 131 into Four way to measure the charge signal and convert it into two paths by the coarse measurement angle signal modulation module 26. Sensing resolver quadrature signal, wherein:

U _{coarse sin} =Usin(wt)sin(θ)

U _{coarse cos} = Usin(wt)cos(θ)

Two coarse resolver quadrature signal obtained by the resolver 24 Solutions coarse count to obtain a crude demodulation module measuring angular displacement θ _crude.

In a preferred embodiment, a switch is respectively disposed on the circuit of the four-way precision measurement capacitor signal and the four-way coarse measurement capacitor signal for realizing time division multiplexing of the signal modulation and demodulation circuit 2, when measuring the precision angular displacement Turn on the switch for controlling the precision measurement capacitor signal, turn off the switch for controlling the coarse measurement capacitance signal; when measuring the coarse angle measurement displacement, turn off the switch for controlling the fine measurement capacitance signal, and turn on to control the coarse measurement capacitance Signal switch.

In a preferred embodiment, as shown in FIG. 10, the absolute differential rotation signal and the coarse orthogonal rotation signal outputted during operation of the absolute capacitance angular displacement measuring sensor of the present invention are shown.

As shown in FIG. 11, the error compensation and fusion module 3 performs error correction on the fine measurement and the coarse measurement of the angular displacement, and the specific process is as follows:

1. Determine the error types of fine measurement and coarse measurement respectively. The error types include harmonic component error, signal amplitude error, noise error, etc.; and according to the error type, the acquired data is identified by data, and the precision measurement and coarse are calculated. Measured error compensation parameters;

2. Obtaining the precision angular displacement and the coarse angular displacement; and generating a compensation function according to the obtained error compensation parameter and the precision angular displacement and the coarse angular displacement, and performing the precision measurement and the coarse angular displacement value respectively through the compensation function Correction, obtaining the correction value of the refined angular displacement and the coarse angular displacement;

3. Calculate the number of splits n of the refined angular displacement relative to the coarse angular displacement according to the formula θ _{R fine} n*θ _R ;

4, _{the solid} according to the formula [theta] = _R * [theta] to give _fine calculated absolute angular n-displacement [theta] _solid.

The specific process of the error compensation and fusion module 3 will be described in detail below with reference to specific embodiments:

Due to the existence of various types of errors, the sine wave and cosine wave of the two obtained orthogonal rotational signals are respectively expressed as:

Where A ₀ and B ₀ represent the DC component of the orthogonal string-changing signal, and A _m and B _m represent the amplitude of the orthogonal string-changing signal, which is the signal amplitude error source;

with

It represents the sum of higher harmonics and is the source of harmonic component error; δ _e represents electrical noise and is the source of noise.

As shown in Figures 12 to 13, the angular displacement after demodulation in this embodiment has a regular and stable error. For high-precision operation requirements, after the angular displacement measurement is completed, it is necessary to correct the above-mentioned error source to establish a trigonometric function. Model protection, compensated by error compensation and fusion module 3 is expressed as:

θ _R =θ _c +(Acos(w ₁ t)+Bcos(2w ₁ )+Ccos(4w ₁ ))

Where θ _R is the angular displacement after compensation, θ _c is the angular displacement before compensation, A, B, and C are the parameters of the compensation function, w ₁ is the electrical cycle frequency; θ _fine and θ are _coarsely compensated to obtain θ _{R fine} And θ _{R is thick} ; the number n of the fine angular displacement relative to the coarse angular displacement is calculated by the formula θ _{R fine} * n*θ _{R coarse} , and the absolute angular displacement is calculated by the formula θ _real = n * θ _R θ _{is actually} sent to the main processor module 2-9.

In a preferred embodiment, the material of the sensitive structure 1 is not limited to the PCB board, but a method of sputtering metal on the glass substrate or directly etching the wire on the silicon substrate may be employed.

In a preferred embodiment, the sensitive structure 1 can be trimmed by laser to reduce the associated manufacturing accuracy.

Example 2:

This embodiment is basically the same as the structure of Embodiment 1, except that the present embodiment replaces the three-piece annular first stator 11, the annular rotor 12, and the annular second stator 13 of the same size in the first embodiment into a two-piece type. The annular stator 14 and the annular rotor 15 of the same size are arranged in parallel with each other as shown in Figs. 14 to 17, and the stator 14 includes the fine measuring collecting electrode 141, the exciting electrode 142, the rough measuring collecting electrode 143 and the charge amplifier ( The rotor 15 includes a precision sensing electrode 151, a coupling electrode 152 and a coarse sensing electrode 153. The bottom of the stator 14 is fixedly provided with a charge amplifier, and the top of the stator 14 is provided with an annular precision measuring electrode 141 from the outside to the inside. The annular excitation electrode 142 and the annular rough measurement acquisition electrode 143; the bottom of the rotor 15 is provided with an annular petal structure precision sensing electrode 151, a ring coupling electrode 152 and an eccentric circular rough sensing sensitive electrode 153 from the outside to the inside, and the rotor 15 passes through the main shaft 154. The fixed connection moving piece; the fine measuring collecting electrode 141 and the fine measuring sensitive electrode 151 are opposite to form a precision measuring capacitance, and the excitation electrode 142 and the coupling electrode 152 are opposite to form a coupling capacitance, and the rough measuring is performed. The collector electrode 143 and the coarse sensing electrode 153 are opposite to each other to form a coarse measurement capacitance.

The above embodiments are only used to illustrate the present invention, and various implementation steps and the like of the method may be changed. Any equivalent transformation and improvement based on the technical solution of the present invention should not be excluded from the present invention. Outside the scope of protection.

Claims (7)

1. An absolute capacitance angular displacement measuring sensor, characterized in that the angular displacement measuring sensor comprises a sensitive structure, a signal modulation and demodulation circuit, an error compensation and fusion module and a power module;

   The sensitive structure includes a stator and a rotor, the stator includes a first stator and a second stator, and the first stator, the rotor and the second stator are sequentially disposed in parallel in a longitudinal direction;

   The first stator includes a fine measurement collecting electrode, a fine excitation electrode and a first charge amplifier, and the first stator bottom is fixedly disposed with the first charge amplifier, and the first stator is disposed outside the top of the first stator Measuring the collecting electrode, the fine sensing excitation electrode is disposed inside the top of the first stator;

   The rotor comprises a precision sensing electrode, a precision measuring coupling electrode, a coarse sensing sensitive electrode and a coarse measuring coupling electrode, wherein the rotor is fixedly connected to the moving member via a main shaft, and the fine sensing sensitive electrode is disposed outside the bottom of the rotor, the rotor The fine sensing coupling electrode is disposed on the inner side of the bottom, and the fine sensing sensitive electrode and the fine measuring coupling electrode are equipotential bodies; the rough sensing sensitive electrode is disposed outside the top of the rotor, and the rough measuring is disposed inside the top of the rotor Coupling the electrode, and the coarse sensing sensitive electrode and the coarse measuring coupling electrode are equipotential bodies;

   The second stator includes a coarse measurement acquisition electrode, a coarse measurement excitation electrode and a second charge amplifier, the second stator top is fixedly disposed with the second charge amplifier, and the second stator bottom is disposed outside the bottom of the second stator. The coarse measuring excitation electrode is disposed on the inner side of the bottom of the second stator; the fine measuring collecting electrode and the fine sensing sensitive electrode are facing each other to form a fine measuring capacitance, and the fine measuring excitation electrode and the fine measuring coupling electrode are facing each other to form a fine Measuring a coupling capacitance, the coarse measurement acquisition electrode and the coarse measurement sensitive electrode are directly opposite to form a rough measurement capacitance, and the coarse measurement excitation electrode and the coarse measurement coupling electrode are opposite each other to form a coarse measurement coupling capacitance;

   The signal modulation and demodulation circuit comprises a fine measurement/and coarse measurement cyclode demodulation module and a fine measurement/and coarse measurement angle signal modulation module, and the fine measurement/and coarse measurement cyclone demodulation module outputs the output carrier signal Applying to the fine/measured excitation electrode after treatment and acting on the fine/cobalt coupling electrode through a fine/and coarse coupling coupling, the fine/coupling coupling electrode will be a carrier signal Passing to the fine/measured sensitive electrode, and performing fine measurement/and coarse measurement capacitance signal by fine measurement/and coarse measurement measurement capacitance to the fine measurement/and coarse measurement acquisition electrode, fine measurement/and coarse The measured capacitance signal is obtained by the corresponding charge amplifier and the fine measurement/and coarse measurement angle modulation module to obtain the fine measurement/and coarse measurement orthogonal rotation signal, and then the fine measurement is obtained by the fine measurement/and coarse measurement and demodulation module. / and coarse angular displacement;

   The error compensation and fusion module is used for error compensation of the precision angular displacement and the coarse angular displacement, and the compensated fine angular displacement and the coarse angular displacement are calculated to obtain an absolute displacement; the power module is used for each The parts are powered.
2. An absolute capacitance angular displacement measuring sensor characterized in that the angular displacement measuring sensor package Including sensitive structure, signal modulation and demodulation circuit, error compensation and fusion module and power module;

   The sensitive structure includes a stator and a rotor, and the stator and the rotor are disposed in parallel;

   The stator includes a fine measurement acquisition electrode, an excitation electrode, a coarse measurement acquisition electrode and a charge amplifier, and the charge amplifier is fixedly disposed on a bottom of the stator, and the fine measurement acquisition electrode and the excitation electrode are sequentially disposed from the outside to the inside of the stator top. And coarse measurement acquisition electrodes;

   The rotor includes a precision sensing electrode, a coupling electrode and a coarse sensing sensitive electrode; the bottom of the rotor is arranged with the fine sensing sensitive electrode, the coupling electrode and the coarse sensing sensitive electrode in order from the outside to the inside, and the rotor is fixedly connected through the spindle. The fine measurement collecting electrode and the fine sensing sensitive electrode are facing each other to form a fine measuring capacitance, the excitation electrode and the coupling electrode are facing each other to form a coupling capacitance, and the coarse measuring collecting electrode and the coarse measuring sensitive electrode are facing each other to form a rough measuring Measuring capacitance;

   The signal modulation and demodulation circuit comprises a fine measurement/and coarse measurement cyclode demodulation module and a fine measurement/and coarse measurement angle signal modulation module, and the fine measurement/and coarse measurement cyclone demodulation module outputs the output carrier signal After the treatment, the excitation electrode is applied to the excitation electrode and the coupling electrode is applied to the coupling electrode, and the coupling electrode transmits a carrier signal to the fine/measured sensitive electrode, and measures the capacitance through the fine measurement and the coarse measurement. Fine measurement/and coarse measurement capacitance signals are obtained to the fine measurement/and coarse measurement acquisition electrodes, and the fine measurement/and coarse measurement capacitance signals are obtained through the corresponding charge amplifiers and the fine measurement/and coarse measurement angle signal modulation modules to obtain fine measurement/and coarse After measuring the orthogonal cyclorotation signal, the fine measurement/and coarse measurement angular displacement is obtained by the fine measurement/and coarse measurement cyclode demodulation module;

   The error compensation and fusion module is used for error compensation of the precision angular displacement and the coarse angular displacement, and the compensated fine angular displacement and the coarse angular displacement are calculated to obtain an absolute displacement; the power module is used for each The parts are powered.
3. The absolute capacitance angular displacement measuring sensor according to claim 1 or 2, wherein the signal modulation and demodulation circuit further comprises a fine measurement carrier signal conditioning module and a coarse measurement carrier signal conditioning module; The carrier signal conditioning module is configured to perform conditioning on the carrier signal output by the fine-measurement variable-rotation demodulation module; and the coarse-measurement carrier signal conditioning module is configured to perform conditioning on the carrier signal output by the coarse-measurement-determined demodulation module.
4. The absolute capacitance angular displacement measuring sensor according to claim 3, wherein the change in the rotation angle of the stator and the rotor converts the rotation angle information into an orthogonal measurement signal by measuring the capacitance change of the fine measurement and the coarse measurement. The specific process is:

   The fine sensing sensitive electrode is a function

   

   And function

   

   

   a ring-shaped petal structure region, wherein R represents a polar circle radius of the petal-like precision sensing electrode, τ represents a half of the width of the fine sensing electrode, and N represents a sine included in the precision sensing electrode The number of cycles,

   

   Denoting a mechanical rotation angle of the rotor and the stator; dividing the oppositely-shaped fine measuring acquisition electrode into a sector-shaped region at intervals of 90° in a sinusoidal period of the precision sensing electrode, and dividing into a sector within a sinusoidal period The four sectoral regions are denoted as S ₀ , S ₉₀ , S ₁₈₀ and S ₂₇₀ , respectively, and the four sector regions are divided into eight sector regions by the inner and outer circles of radius R, respectively:

   

   Where θ represents the measured output angle and has a relationship:

   

   The _outer region connecting _the region S ₀ S _180, S ₉₀ are connected _{in the} region _{outside the} region S _270, S _{180 in the} region _outside the connection area S ₀ and _the area S ₉₀ S ₂₇₀ connected to _{an outer} area of the obtained fine sensing electrodes and sensitive Fine The four facing areas of the facing area of the collecting electrode that vary with the angle of rotation are expressed as:

   

   Wherein A represents the DC component of the facing area, and B represents the amplitude determined by the parameters R, τ; and the four facing regions formed by the fine sensing sensitive electrode and the fine measuring collecting electrode in each sinusoidal period are respectively connected:

   

   A multi-stage capacitor formed by four facing regions within one sinusoidal period is denoted as C ₁ , C ₂ , C ₃ and C ₄ , respectively, and a multi-stage capacitor C ₁ of N sinusoidal periods in the precision sensing electrode C ₂ , C ₃ and C ₄ are connected to obtain four precision measurement capacitor signals C _N1 , C _N2 , C _N3 and C _N4 .
5. An absolute capacitance angular displacement measuring sensor according to claim 4, wherein the carrier signal is applied to the coupling electrode of the rotor without contact by the excitation electrode of the stator design, and the stator is designed according to the above design. The four-channel precision measurement capacitor signal amplified by the corresponding charge amplifier is obtained on the collection electrode, and the four-way precision measurement capacitance signal is obtained, and the two-way precision measurement orthogonal rotation signal is obtained through the fine rotation angle signal modulation module, and the rotation is obtained. The demodulation module cooperates with the obtained two-way precision orthogonal torsion signal and the output carrier signal to calculate the precise angular displacement. The specific process is as follows:

   The four-way fine-charged charge signals obtained by the four-way precision-measured capacitor signals through the corresponding charge amplifiers are respectively expressed as:

   

   Wherein w represents the frequency at which the fine-tuning resolver demodulation module outputs a sinusoidal excitation signal, sin(wt) represents a carrier signal acting on the fine excitation electrode, and d represents a spacing between the stator and the rotor; The road fine charge signal is obtained by the fine angle signal modulation module to obtain two precision orthogonal polarization signals, which are respectively represented as:

   U _{fine sin} =Usin(wt)sin(θ)

   U _{fine cos} = Usin(wt)cos(θ)

   The obtained two-way fine orthogonal vibration signal is solved by the fine-precision cyclode demodulation module to obtain the refined angular displacement θ _fine .
6. The absolute capacitance angular displacement measuring sensor according to claim 5, wherein the change in the rotation angle of the stator and the rotor is converted into a capacitance by a rough measurement, a corresponding charge amplifier, and the coarse-measurement demodulation module Two-way coarse measurement of the orthogonal rotation signal, and then calculate the coarse angular displacement, the specific process is:

   The coarse sensing sensitive electrode is an eccentric ring with an eccentricity d, and the ring-shaped coarse measuring collecting electrode is divided into a sector-shaped area every 90°, and the four sector-shaped regions are further divided into eight sectors by a circle having a radius R. region, are represented by S _{'the 0,} S' _{within 90,} S _{'within 180 [,} S' _{within 270,} S _{'outside 0,} S' _{90, the} S _{'180 [outer} and S' _{270 outside} the region S _{'0 The} rough sensing sensitive electrode is obtained _{outside the inner} connecting region S' _{180, outside the} connecting region S' _{270 in the} region S' _{90, outside the} connecting region S' _{0 in the} region S' _{180 ,} and _{outside the} connecting region S' _{90 in the} region S' _270. And the four pairs of positively facing areas of the rough-measured collecting electrode vary with the angle of rotation; the multi-level capacitors formed by the four facing regions in one sinusoidal period are denoted as C ₅ , C ₆ , C ₇ and C _{8 , respectively} ; The corresponding charge amplifier converts the four-way coarse-measurement capacitance signal collected by the coarse-measurement acquisition electrode into four-way coarse-measurement charge signal, and converts the two-way coarse-measurement orthogonal-rotation signal by the coarse-measurement angle-angle signal modulation module. among them:

   U _{coarse sin} =Usin(wt)sin(θ)

   U _{coarse cos} = Usin(wt)cos(θ)

   The obtained two-way coarse-measurement orthogonal rotatory signal is solved by the coarse-measurement variable-rotation demodulation module to obtain a coarse angular displacement θ _coarse .
7. The absolute capacitance angular displacement measuring sensor according to claim 6, wherein the error compensation and fusion module comprises a fine measurement/and coarse measurement error compensation module; and the fine measurement/and coarse measurement error compensation module The error compensation is performed on the fine measurement/coarse angular displacement, and the compensated fine measurement/and coarse measurement angular displacement are calculated by the absolute displacement. The specific process is:

   Determine the error type of fine measurement and coarse measurement respectively. The error types include harmonic component error, signal amplitude error and noise error. According to the error type, the acquired data is identified by data, and the error of fine measurement and coarse measurement is calculated. Compensation parameter

   Obtaining the fine measurement/and coarse measurement angular displacement; and generating a compensation function according to the obtained error compensation parameter and the fine measurement/and coarse measurement angular displacement, and correcting the fine measurement/and coarse measurement angular displacement values respectively by the compensation function to obtain the fine Correction value of measured/and coarse angular displacement;

   Calculating the number n of the fine angular displacement relative to the coarse angular displacement according to the formula θ _{R fine} n*θ _R ;

   The absolute angular displacement θ _is calculated according to the formula θ _real = n * θ _R.

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