DE102022213659A1 - Method and position detection system for generating a robust position signal - Google Patents

Abstract

The invention relates to a method for generating a robust position signal for determining a position of a movable element, wherein the movable element is arranged in the xy plane with respect to an x,y,z coordinate system and is movable in an x-direction, comprising
at least one first magnet (1) which has a magnetization and which is arranged on or in relation to the movable element and to which a first magnetic field is assigned, and
at least one Hall sensor which is arranged relative to the first magnet (1) for detecting the first magnetic field and which is designed to generate a position signal which represents the position of the movable element along the x-direction.
Furthermore, the invention relates to a position detection system and a use.

Description

The invention relates to a method for generating a robust position signal for determining a position of a movable element as well as a position detection system and a use.

Magnetic field sensors can be used to measure magnetism, such as the direction, strength, or relative change of the magnetic field at a particular location. Such information can be used in a variety of applications, where the sensed magnetic field parameters can be used to control electronic systems.

Magnetic sensors include, for example, magnetoresistive sensors and Hall effect sensors (Hall sensors). A Hall sensor is a transducer that varies its output voltage (Hall voltage) in response to a magnetic field. It is based on the Hall effect, which uses the Lorentz force. The Lorentz force causes moving charge to deflect in the presence of a magnetic field that is perpendicular to the current flowing through the sensor or Hall plate. A Hall plate can be a thin piece of semiconductor or metal. The deflection causes charge separation, which creates an electric field. This electric field acts on the charge in the opposite direction to the Lorentz force. Both forces cancel each other out, creating a potential difference perpendicular to the direction of current flow. The potential difference can be measured as what is called the Hall voltage, and it varies in a linear relationship with the magnetic field.

However, such Hall sensors have a disadvantage in terms of range and stray field robustness. Stray fields are magnetic fields introduced by magnetic harsh environments or other external means located in the immediate vicinity of the sensor. A magnetic harsh environment can be caused by large current densities near the sensor (hybridization of vehicles) or electric motors next to the sensing location. Stray field disturbance can cause inaccuracies in the signals generated by the sensor and can affect the overall behavior of the sensor system, for example in terms of range.

The EN 10 2012 205902 A1 discloses a displacement sensor for contactlessly measuring a position of a magnet relative to a reference point, which comprises: the magnet, which is displaceable along a movement axis, a plurality of magnetic field sensors arranged in series, which are arranged parallel to the movement axis, and a calculation unit for forming a position signal which indicates the position of the magnet relative to the reference point, wherein each magnetic field sensor has a zero point and a displacement measuring range and is designed such that it outputs an output signal which indicates a position of the magnet relative to the zero point of the magnetic field sensor, and the accuracy with which the output signal indicates the position of the magnet decreases with increasing distance of the magnet from the zero point, the plurality of magnetic field sensors arranged in series are arranged such that the displacement measuring ranges of adjacent magnetic field sensors overlap in an overlap region, and the calculation unit is designed such that, when the position of the magnet is contained in an overlap region, it forms the position signal on the basis of output signals which are output by the Magnetic field sensors are output whose position measuring ranges overlap in the overlap region, and if the position of the magnet is not contained in an overlap region, it forms the position signal based on the output signal output by the magnetic field sensor in whose position measuring range the magnet is located, and the overlap region between two position measuring ranges of adjacent magnetic field sensors is selected such that the total error of the position signal formed by the calculation unit in this overlap region is smaller than a maximum tolerable error.

It is therefore an object of the invention to provide a method and a position detection system for generating a stray field robust position signal of a movable element with the greatest possible range.

This object is achieved by a method having the features of claim 1 and a position detection system having the features of claim 9 and a use having the features of claim 12.

The subclaims list further advantageous measures which can be suitably combined with one another to achieve further advantages.

• - Erfassen einer auf das x,y,z- Koordinatensystem abgestimmten ersten magnetischen Raumkoordinate, und einer zweiten magnetischen Raumkoordinate und einer dritten magnetischen Raumkoordinate, anhand einer magnetischen Flussdichte des ersten Magnetfeldes des zumindest einen ersten Magneten, wobei die zweite magnetische Raumkoordinate anhand einer entsprechenden Anordnung des Hallsensors und/oder des zumindest einen ersten Magneten erzeugt wird,
• - Bestimmen eines ersten magnetischen Winkels anhand der ersten Raumkoordinate und der dritten Raumkoordinate und eines zweiten im Bereich von 180° gegenüber dem ersten magnetischen Winkel verschobenen zweiten magnetischen Winkels,
• - Bereitstellen eines Schwellenwertes für den ersten magnetischen Winkel, welcher auf die Anordnung des zumindest einen ersten Magneten und den Hallsensor abgestimmt ist,
• - Heranziehen des ersten magnetischen Winkels als Positionssignal wenn der erste magnetische Winkel unterhalb des Betrags des Schwellenwertes liegt, und
• - wenn der erste magnetische Winkel oberhalb des Schwellenwertes liegt:
  • o Erhöhen des zweiten magnetischen Winkels um etwa 180°, wenn die zweite magnetische Raumkoordinate positiv ist und heranziehen des so erhöhten zweiten magnetischen Winkels als Positionssignal,
  • o Reduzieren des zweiten magnetischen Winkels um etwa 180°, wenn die zweite magnetische Raumkoordinate negativ ist und heranziehen des so reduzierten zweiten magnetischen Winkels als Positionssignal.

The object is achieved by a method for generating a robust position signal for determining a position of a movable element, wherein the movable element is arranged in relation to an x,y,z coordinate system in the xy plane and is movable in an x direction, comprising at least one first magnet which has a magnetization and which is arranged on or in relation to the movable element and to which a first magnetic field is assigned, and
at least one Hall sensor which is arranged relative to the at least one first magnet for detecting the first magnetic field and which is designed to generate a position signal which represents the position of the movable element along the x-direction,
comprising the steps:

• - detecting a first magnetic spatial coordinate, which is coordinated with the x,y,z coordinate system, and a second magnetic spatial coordinate and a third magnetic spatial coordinate, based on a magnetic flux density of the first magnetic field of the at least one first magnet, wherein the second magnetic spatial coordinate is generated based on a corresponding arrangement of the Hall sensor and/or the at least one first magnet,
• - determining a first magnetic angle based on the first spatial coordinate and the third spatial coordinate and a second magnetic angle shifted in the range of 180° with respect to the first magnetic angle,
• - Providing a threshold value for the first magnetic angle, which is adapted to the arrangement of the at least one first magnet and the Hall sensor,
• - Using the first magnetic angle as a position signal if the first magnetic angle is below the threshold value, and
• - if the first magnetic angle is above the threshold:
  • o Increasing the second magnetic angle by approximately 180° if the second magnetic spatial coordinate is positive and using the thus increased second magnetic angle as a position signal,
  • o Reducing the second magnetic angle by approximately 180° if the second magnetic spatial coordinate is negative and using the reduced second magnetic angle as a position signal.

In particular, the x,y,z coordinate system is a Cartesian coordinate system. In particular, the x,y,z coordinate system only serves to describe the relative coordinates and the spatial coordinates to one another; the method can be applied, for example, to a rotated or different coordinate system. Thus, the x-direction/z-direction can also be designed as a different direction and only serves here to set the individual components in relation to one another and should therefore not represent a restriction. In particular, the at least one first magnet has a magnetization in the z-direction.
The magnetization can also be in a different direction, for example; the method can also be applied to magnets with magnetization in the x-direction, for example.

In particular, the second magnetic angle is reduced or increased by exactly 180°.

By a corresponding arrangement of the Hall sensor in relation to the at least one first magnet, the second magnetic spatial coordinate has a value other than zero.

The Hall sensor, in particular a 3D Hall sensor, is arranged above/below the at least one first magnet as seen in the z-direction.

The direction of movement (x-direction) of the element corresponds to the direction of movement of at least a first magnet.

The method according to the invention uses a further, here second, spatial coordinate, in addition to the first spatial coordinate and third spatial coordinate required to calculate the magnetic angle, to increase the range. Using a first magnetic angle and a second magnetic angle shifted by 180°, as well as a threshold value, a combined magnetic stray field robust angle can be generated, which has a greater range, taking into account a positive or negative value of the second spatial coordinate. This takes into account that the second spatial coordinate changes sign along the x-direction.

In particular, as described, the second spatial coordinate is used, which has a value not equal to zero due to a corresponding arrangement, in particular here due to a tilting of the magnetization, and/or tilting of the magnet and/or rotation of the sensor.

This knowledge is now used to generate the different magnetic angles depending on the sign change and the threshold value.

In a further development, the threshold value is selected depending on the distance between the two magnets and the Hall sensor. Furthermore, the threshold value is also selected in relation to the desired range extension. In particular, the threshold value is selected so that the second spatial coordinate is already outside the zone of the sign change around the zero point.

In a further embodiment, the magnetic angle is formed using the arctan function or the atan2 function.

In further development, the Hall sensor is designed as a stray field robust 3D Hall sensor.

As a result, the resulting second spatial coordinate, which has a value other than zero due to the corresponding arrangement, such as here the tilting of the magnetization, or tilting of the magnets, rotation of the sensor, is also formed by subtracting the two second different magnetic measured values.

In a further embodiment, the first magnet has a magnetization, and at least one second magnet is provided, which has a magnetization that is different from the first magnet, for example mirrored along the z-direction and identical along the y-direction or rotated, in particular by between 140° and 220°, and which is arranged on or in relation to the movable element at a defined distance from the first magnet, and to which a second magnetic field is assigned, and wherein the first magnetic field and the at least second magnetic field form a resulting total magnetic field, and wherein the Hall sensor, which is arranged relative to the at least one first magnet and the second magnets, detects the resulting total magnetic field. Furthermore, several magnets can also be present.

In a further embodiment, the Hall sensor measures two first different magnetic measurement values and two second different magnetic measurement values and two third different magnetic measurement values on opposite sides of the Hall sensor based on the resulting magnetic field, and wherein the respective spatial coordinate is formed by the difference between the respective corresponding measurement values and wherein the magnetic angle is formed using the atan function or the atan2 function from the first spatial coordinate and the third spatial coordinate.

In a further embodiment, a measurable second spatial coordinate is generated by rotating the Hall sensor about the z-axis in relation to the x-direction of the movable element. This means in particular that the 3D Hall sensor generates a dBy component that is not equal to zero and therefore has a value that is different from zero.

This rotation increases the asymmetry between the left and right sides of the Hall sensor with respect to the y-component. A rotation of around 20° is sufficient.

In a further embodiment, the measurable second spatial coordinate is generated by tilting the magnets in relation to the x-direction, i.e. here the x-axis, of the movable element. Optionally or additionally, the measurable second spatial coordinate is realized by magnetizing the at least one magnet tilted around the x-axis. This breaks the symmetry of the magnetic field in the y-direction. The symmetry can also be broken by moving the magnet and sensor relative to each other along the y-axis.

In further development, the tilt of the magnet(s) or their magnetization is in the range of 20°.

Furthermore, the object is achieved by a position detection system for generating a robust position signal for determining a position of a movable element, wherein the movable element is arranged in the xy plane with respect to an x,y,z coordinate system and is moved in an x-direction. bar, comprising at least a first magnet which has a magnetization and which is arranged on or in relation to the movable element and to which a first magnetic field is assigned, and
at least one Hall sensor which is arranged relative to the at least one first magnet for detecting the first magnetic field and which is designed to generate a position signal which represents the position of the movable element along the x-direction, and
wherein the Hall sensor is designed to generate a first magnetic spatial coordinate matched to the x,y,z coordinate system and a second magnetic spatial coordinate and a third magnetic spatial coordinate based on a magnetic flux density of the first magnetic field of the at least one first magnet,
and/or wherein the Hall sensor is rotated about the z-axis with respect to the x-direction of the movable element, for generating a measurable second spatial coordinate by the Hall sensor and/or wherein the at least one first magnet is tilted with respect to the x-direction of the movable element and/or its magnetization is tilted with respect to the x-direction of the movable element, for generating a measurable second spatial coordinate.

The advantages of the method can be transferred to the position detection system. In particular, the position detection system is designed to carry out the method.

Furthermore, the position detection system has an evaluation unit for determining a first magnetic angle based on the first spatial coordinate and the third spatial coordinate and a second magnetic angle shifted in the range of 180° relative to the first magnetic angle, and wherein a storage unit is also provided with a threshold value for the first magnetic angle, wherein the threshold value is matched to the arrangement of the at least one first magnet and the Hall sensor,
and a calculation module is provided which is designed to use the first magnetic angle as a position signal if the first magnetic angle is below the amount of the threshold value and which is further designed to increase the second magnetic angle by approximately 180° if the second magnetic spatial coordinate is positive and to use the second magnetic angle thus shifted as a position signal and wherein the calculation module is further designed to reduce the second magnetic angle by approximately 180° if the second magnetic spatial coordinate is negative and to use the second magnetic angle thus shifted as a position signal.

In particular, the x,y,z coordinate system is a Cartesian coordinate system. In particular, the x,y,z coordinate system only serves to describe the relative coordinates and the spatial coordinates to one another; the method can be applied, for example, to a rotated or different coordinate system. Thus, the x-direction/z-direction can also be designed as a different direction and only serves to relate the individual components to one another. In particular, the first magnet has a magnetization in the z-direction. The magnetization can also be in a different direction, for example; the method can also be applied to magnets with a magnetization in the x-direction, for example.

In a further embodiment, the first magnet has a magnetization, and at least one second magnet is provided which has a magnetization that is different from the first magnet, for example mirrored along the z-direction and identical along the y-direction or rotated, in particular by between 140° and 220°, and which is arranged on or in relation to the movable element at a defined distance from the first magnet, and to which a second magnetic field is assigned, and wherein the first magnetic field and the at least second magnetic field form a resulting total magnetic field, and wherein the Hall sensor is arranged relative to the at least one first magnet and to the second magnet for detecting the resulting total magnetic field.

Furthermore, the object is achieved by using the method as described above and/or the position detection system as described above in a linear system or in an angle measuring system which is designed to carry out angle measurements in a limited angular range.

In particular, the angle measuring system is designed for angle measurements in the range of +/-30°.

This can be the case, for example, in a system with a height sensor.

• 1: ein Erfassungssystem für eine Position gemäß dem Stand der Technik,
• 2: ein 3D-Hallsensor,
• 3: die Magnetanordnung gemäß dem Stand der Technik,
• 4: ein Diagramm zu der Magnetanordnung in 3,
• 5: das erfindungsgemäße Verfahren,
• 6: eine Anordnung der beiden Magnete zur Erzeugung einer zweiten Raumkoordinate,
• 7: ein Diagramm zu der Anordnung in 6,
• 8: eine weitere Anordnung der beiden Magnete zur Erzeugung einer zweiten Raumkoordinate,
• 9: ein Diagramm zu der Anordnung in 8,
• 10: ein Diagramm mit den gemessenen magnetischen Winkeln,
• 11: die generierten verschiedenen magnetischen Winkel gemäß der Erfindung,
• 12: schematisch ein lineares Positionssensorsystem mit einem einzelnen Scheibenmagneten,
• 13: ein Diagramm zu der Anordnung in 12,
• 14: die generierten verschiedenen magnetischen Winkel zu obiger Anordnung,
• 15: Verwendung eines erfindungsgemäßen Positionserfassungssystem und einem Verfahren in einem Winkelsensor.

Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying figures, which schematically show:

• 1 : a position detection system according to the state of the art,
• 2 : a 3D Hall sensor,
• 3 : the magnet arrangement according to the state of the art,
• 4 : a diagram of the magnet arrangement in 3 ,
• 5 : the method according to the invention,
• 6 : an arrangement of the two magnets to generate a second spatial coordinate,
• 7 : a diagram of the arrangement in 6 ,
• 8th : another arrangement of the two magnets to generate a second spatial coordinate,
• 9 : a diagram of the arrangement in 8th ,
• 10 : a diagram with the measured magnetic angles,
• 11 : the generated different magnetic angles according to the invention,
• 12 : schematically a linear position sensor system with a single disc magnet,
• 13 : a diagram of the arrangement in 12 ,
• 14 : the generated different magnetic angles to the above arrangement,
• 15 : Use of a position detection system according to the invention and a method in an angle sensor.

1 shows a detection system 100 for a position according to the prior art. This has an element 101 that is movable in the x-direction.

A first magnet 102 and a second magnet of the same size 104 are arranged on the movable element 101. The movable element 101 has an x,y,z coordinate system and can be moved in the x direction.

The first magnet 102 has a magnetization in the positive z-direction. Furthermore, a first magnetic field 103 is assigned to the first magnet 102.

The second magnet 104 has a magnetization in the negative z-direction. Furthermore, a second magnetic field 106 is assigned to the second magnet 104.

A magnetic field sensor 105 is arranged in a fixed position in the z-direction. This is designed to detect the resulting total magnetic field formed by the first magnetic field 103 and the second magnetic field 106.

The magnetic field sensor 105 is thus designed to detect two orthogonal magnetic field components that are coordinated with the x, y, z coordinate system, namely the magnetic spatial coordinate Bx, which runs along the direction of movement (x direction), where Bx is the first magnetic spatial coordinate and Bz is a third magnetic spatial coordinate that runs perpendicular to it. The magnetic field sensor 105 detects these based on the magnetic flux density of the resulting total magnetic field of the first magnet 102 and the second magnet 104.

The magnetic field sensor 105 is designed to generate a magnetic angle α _mag as an angle signal for determining the position of the movable element 101, wherein the angle signal indicates the angle at which the magnetic field lines emanating from the magnets 102, 104 of the movable element 101 strike the magnetic field sensor 105.

In particular, the magnetic field sensor 105 can be implemented as a 3D Hall sensor 109.

2 shows a typical Hall plate arrangement as a so-called 3D Hall sensor 109. This has a plate center 112 and several horizontal or vertical Hall plates 108 (only two shown here) as well as a right Hall plate side 110 and a left Hall plate side 111.

For a conventional (not stray field robust) evaluation, the flux densities Bx1 and Bz1 measured on the rightmost side of the Hall plate 110 are used to determine the magnetic angle α _mag as follows: $${\alpha }_{maG}=\text{atan2}\left(\frac{B_{z1}}{B_{x1}}\right)$$

For a stray field robust evaluation of a magnetic angle α _mag of an angle signal as a position signal, the flux densities Bx1, Bx4 and Bz1, Bz4 measured at the extreme right Hall plate side 110 and the extreme left Hall plate side 111 are used as follows: $${\alpha }_{maG}=\text{atan2}\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="B\; z"\; filenames="DE102022213659A1\_0011.png,DE102022213659A1\_0012.png"\; state="\{\{state\}\}">B</figure-callout>}}_z-B_{z4}}{B_{x1}-B_{x4}}\right)$$

From (II) it can be seen that the resulting angle α _mag is not influenced by a homogeneous stray field which has the same amplitude on both sides of the Hall plate 110,111, since it is compensated in the calculation.

However, the achievable range is greatly limited with such 3D Hall sensors 109. On the one hand, the magnetic field amplitude must be above a certain value so that the noise and the drift within the sensor do not distort the position signal too much. On the other hand, the range of the magnetic angle α _mag that is covered on the path must be below 360°. Otherwise, the position signal is not clear.

This problem is exacerbated in the stray field robust measurement, since the magnetic angle α _mag increases over the travel path up to twice as fast as in the conventional (non-strewn field robust) evaluation.

If such a 3D Hall sensor is used in 3 or 1 used, the difference dBy between the measured flux densities By1 and By4 is zero.

3 shows the magnet arrangement with the first magnet 102 and the second magnet 104 for a linear sensor system. The magnets 102,104 are cuboid-shaped with a length of 10mm, a width of 6mm and a height of 3mm and consist of sintered NdFeB magnets. The magnets 102,104 have opposing magnetic poles (arrows).

In this example the air gap is 5mm and the distance between the magnets is 2mm.

4 shows the diagram of the magnet arrangement in 3 calculated magnetic angle α _mag as a function of the range in mm. This magnetic angle α _mag can be mapped to the position of the magnets 102,104. In the case of the stray field robust calculation, this is almost linear.

The diagram shows a 2pi jump in the position signal beyond 18mm for a non-stray field robust evaluation (conventional) or 12mm for a stray field robust evaluation (stray field robust). From this position onwards, the position signal is no longer clear. It can be seen from the diagram that in the conventional case a measuring range (range) of 36mm (18mm +18mm) is possible, but in the stray field robust case only a measuring range (range) of 24mm (12mm +12mm) is possible.

5 shows the method according to the invention schematically. This also has a movable element as in the prior art. The movable element has an x,y,z coordinate system and can be moved in the x direction as the x direction. However, all coordinate axes can be interchanged, the method can also be used if the movable element is detected in the y direction, for example, with a correspondingly generated magnetic field, or the entire coordinate system is rotated. The movable element comprises a first magnet 1 and a second magnet of the same size 2 ( 6 ) are arranged. Several magnets can also be arranged. The magnets 1,2 have a tilted magnetization in order to produce a value of dBy that is not equal to zero, ie in order to maintain the symmetry with respect to the Hall plate sides 110,111 ( 2 ) towards By ( 6 ) to break.

In the z-direction, a 3D Hall sensor 3 ( 8th ) which is arranged relative to the first magnet 1 and second magnet 2 for detecting the total magnetic field.

Furthermore, the 3D Hall sensor 3 ( 8th ) designed to detect magnetic spatial coordinates dBx, dBy, dBz coordinated to the x,y,z coordinate system, where dBx forms a first magnetic spatial coordinate and dBy a second magnetic spatial coordinate and dBz a third magnetic spatial coordinate.

These are detected in a first step S1 based on a magnetic flux density of the resulting total magnetic field of the at least two magnets 1, 2. The second magnetic spatial coordinate dBy is thereby achieved based on a corresponding offset arrangement of the magnetic field sensor in the y-direction and the at least two magnets 1, 2 relative to one another in order to obtain a spatial coordinate dBy that is different from zero.

Such an arrangement is in 6 and an alternative or additional arrangement in 8th shown.

6 shows such a first arrangement to obtain a spatial coordinate dBy that is different from zero. dBy corresponds to a stray field robust second spatial coordinate, which is determined by a difference between the spatial coordinate measured by the 3D Hall sensor 3 ( 8th ) measured left flux density By4 and right flux density By1.

In order to obtain such a value that is not equal to zero, the arrangement is constructed in such a way that the symmetry with respect to the y-component of the magnetic field is broken. This is achieved here by tilting the magnetization of the magnets 1,2 around the x-axis (arrow), with the tilt being in the range of about 20°. This makes it possible to achieve a sufficiently large measurement value of the second spatial coordinate dBy.

Alternatively or additionally, the symmetry with respect to the y-component of the magnetic field can be broken by tilting the magnets 1, 2 themselves. A combination of tilting the magnetization and the magnets 1, 2 can also be present. The symmetry can also be broken by moving the magnets 1, 2 and the 3D Hall sensor 3 relative to each other along the y-axis.

7 shows the second spatial coordinate dBy in a diagram with such a tilting due to the tilting of the magnets 1,2 or the tilting of the magnetization of the magnets 1,2 against the range. The strength of the amplitude in mT, of an arrangement with non-tilted magnets as dBy standard and with magnetically tilted magnets 1,2 as dBy-option1, is plotted against the range in mm. It can be seen that the value of dBy (dBy-standard) is zero for non-tilted magnets, and a value other than zero for magnets1,2 with tilted magnetization (alternatively or additionally tilted magnets 1,2) (dBy-option1). The difference norm diff.norm-option1 is also plotted, which is determined from the spatial coordinates dBx and dBz components. The decrease in the difference norm is, however, very small compared to the original difference norm diff.norm-standard, and is therefore not significant.

8th shows another arrangement of the two magnets 1,2 to obtain a spatial coordinate dBy different from zero.

In this arrangement, the 3D Hall sensor 3 is also rotated around the z-axis. This rotation can also be carried out alternatively. The rotation can, for example, be in the range of 20° relative to the direction of movement (x-direction) of the magnets 1, 2 (shown here as arrows). This rotation further increases the asymmetry between the left and right sides of the 3D Hall sensor 3 in relation to the y-component.

Alternatively or additionally, in addition to the rotation and tilting of the magnets 1,2, a linear displacement of the 3D Hall sensor 3 along y can also contribute to increasing the value of dBy (not shown).

9 shows the second spatial coordinate dBy (dBy-option2) in a diagram with a magnetic tilt and such an additional rotation of the 3D Hall sensor 3. In the diagram it can be seen that the additional rotation of the 3D Hall sensor 3 (here marked as dBy-option2) increases the second spatial coordinate dBy by more than a factor of two compared to only tilted arrangement/magnetization (dBy-option1).

The difference norm diff.norm-option 2 is also shown, which is determined from the spatial coordinates dBx and dBz components. This is still acceptable.

It can be seen that the sign of the second spatial coordinate dBy (dBy-option2) changes in the direction of movement of the element. Below a position of |x|<5mm, the spatial coordinate dBy changes sign in this example. In this example, above a position of |x| = 5mm, the value of dBy is large enough, i.e. dBy no longer changes sign.

Therefore, the sign of the second spatial coordinate dBy can be used to extend the measuring range, i.e. the range.

Ferner wird ein um 180° verschobener Winkel α_{mag,verschoben} erzeugt.For this purpose, in a second step S2 ( 5 ), after the three spatial coordinates dBx, dBy, dBz have been recorded by the 3D Hall sensor 3, the magnetic angle α _mag is first determined: $${\alpha }_{maG}=\text{atan2}\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="B\; z"\; filenames="DE102022213659A1\_0011.png,DE102022213659A1\_0012.png"\; state="\{\{state\}\}">B</figure-callout>}}_z-B_{z4}}{B_{x1}-B_{x4}}\right)$$

Furthermore, an angle α _mag,shifted is generated that is shifted by 180°.

In 10 A diagram shows the magnetic angle α _mag measured for the magnet/Hall sensor arrangement option 2 as a function of the range in mm and the magnetic angle α _{mag shifted by 180°, shifted} with the 2pi jumps.

In a further step S3 ( 5 ) a threshold value β is set for α _mag . The threshold value β depends on the respective arrangement, for example how far the 3D Hall sensor 3 is from the magnets 1,2 and how far the range is to be extended. In this example, the threshold value β is selected as 90°. This ensures that dBy is already outside the zone of the sign change around the zero point.

In a subsequent step S4, the magnetic angle α _mag is _{combined as α mag} ( 11 ) to determine the position of the magnets 1,2 and thus of the movable element. The magnetic angle α _mag is only used if α _mag is smaller than the selected threshold value β: $$-\mathrm{\beta <}{\alpha }_{maG}<\mathrm{\beta }$$

In an alternative step S4a ( 5 ) the sum of α _{mag,is shifted} and 180° _{combined as α mag,} ( 11 ) is used to determine the position of the magnets 1,2 and thus of the movable element. The sum of α _{mag, shifted} and 180° is only used if the sign of dBy is positive: $${\alpha }_{maG,kOmbiniert}={\alpha }_{maG,verscHOben}+180°\text{only then}\text{, if dBy}>0$$

In an alternative step S4b, the difference of α _{mag, shifted} and 180° is used as α _{mag, combined} to determine the position of the magnets 1,2 and thus of the movable element.
The difference of α _mag,shifted and 180° is only used if the sign of dBy is negative: $${\alpha }_{maG,kOmbiniert}={\alpha }_{maG,verscHOben}-180°\text{only then}\text{, if dBy}<0$$

This takes into account the fact that, for example, from a position of |x|<5m the second spatial coordinate dBy changes sign.

The combined magnetic angle α _mag,combined can now cover a larger range.

$${\alpha }_{mag,kombiniert}={\alpha }_{mag,verschoben}-180°\text{ nur dann}\text{, wenn dBy}>0$$

It should be noted that in the case of reverse magnetization the same applies with opposite signs, ie: $${\alpha }_{maG,kOmbiniert}={\alpha }_{maG,verscHOben}+180°\text{only then}\text{, if dBy}<0$$

$${\alpha }_{maG,kOmbiniert}={\alpha }_{maG,verscHOben}-180°\text{only then}\text{, if dBy}>0$$

11 shows the magnetic angle α _{mag, combined} as well as the magnetic angle α _mag and the magnetic angle α _{mag, shifted} over the range in mm in a diagram.

It can be seen that in this example, due to the magnetic angle α _{mag, a combined} measuring range of approx. +/-20mm is possible, which means an increase of approx. 66% compared to the original range.

It should be noted that this can vary depending on the sensor. In contrast, the problem with the 2pi jump is inherent and can be overcome according to the invention by the method/position sensor system.

By means of such a method according to the invention, the range can therefore be significantly increased with a stray field robust evaluation.

The method according to the invention can also be transferred to angle measurements with a limited angle range, for example +/-30°, for example in a height sensor.

12 shows a schematic of a linear position sensor system with a single disc magnet 4. In this example, it has a diameter of 8 mm and a height of 4.5 mm and an air gap of 5 mm.

13 shows the second spatial coordinate dBy in this example as a diagram. Originally the magnetization points in the z direction, so that no dBy component occurs due to the symmetry (dBy standard). Now the magnetization is rotated by 30° (dBy option1). This leads to a value for dBy that is different from zero. If the sensor (not shown) is now moved by 2 mm along y, the value dBy increases further (dBy option2).

In 14 It can be seen that the combined signal α _mag,combined provides clear information up to 30 mm, which, however, should not be fully exploited due to the low amplitude.

In 15 shows the use of a position detection system according to the invention and a method in an angle sensor 5 for angle measurements in a limited angular range, for example +/-30°.

List of reference symbols

100

Recording system (state of the art)

101

movable element (state of the art)

102

first magnet (state of the art)

103

first magnetic field (state of the art)

104

second magnet (state of the art)

106

second magnetic field (state of the art)

107

Magnetic field sensor 1 (state of the art)

108

Hall plates (state of the art)

109

3D Hall sensor (state of the art)

110

right side of the reverb plate (state of the art)

111

left side of the reverb plate (state of the art)

112

Plate center (state of the art)

1

first magnet

2

second magnet

3

3D Hall sensor

4

Disc magnet

5

Angle sensor

QUOTES INCLUDED IN THE DESCRIPTION

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Cited patent literature

• DE 102012205902 A1 [0005]

Claims (12)

Method for generating a robust position signal for determining a position of a movable element, wherein the movable element is arranged in relation to an x,y,z coordinate system in the xy plane and is movable in an x-direction, comprising at least one first magnet (1) which has a magnetization and which is arranged on or in relation to the movable element and to which a first magnetic field is assigned, and at least one Hall sensor which is arranged relative to the first magnet (1) for detecting the first magnetic field and which is designed to generate a position signal which represents the position of the movable element along the x-direction, characterized by the steps: - detecting a first magnetic spatial coordinate (dBx) matched to the x,y,z coordinate system, and a second magnetic spatial coordinate (dBy) and a third magnetic spatial coordinate (dBz), based on a magnetic flux density of the first magnetic field of the at least one first magnet (1), wherein the second magnetic spatial coordinate (dBy) is determined based on a corresponding arrangement of the Hall sensor and/or the at least one first magnet (1), - determining a first magnetic angle (α _mag ) based on the first spatial coordinate (dBx) and the third spatial coordinate (dBz) and a second, in the range of 180° in magnitude, second magnetic angle (α _{mag , shifted} ) shifted relative to the first magnetic angle (α mag ), - providing a threshold value (β) for the first magnetic angle, which is matched to the arrangement of the at least one first magnet (1) and the Hall sensor, - using the first magnetic angle (α _mag ) as a position signal if the first magnetic angle (α _mag ) is below the amount of the threshold value (β), - if the first magnetic angle (α _mag ) is above the threshold value (β): ◯ increasing the second magnetic angle (α _{mag, shifted} ) by approximately 180° if the second magnetic spatial coordinate (dBy) is positive and using the thus increased second magnetic angle (α _mag,shifted ) as a position signal, or ◯ reducing the second magnetic angle (α _mag,shifted ) by about 180° if the second magnetic spatial coordinate (dBy) is negative and using the thus reduced second magnetic angle (α _mag,shifted ) as a position signal. Procedure according to Claim 1 , characterized in that the threshold value (β) is selected depending on the distance of the at least one first magnet (1) to the Hall sensor. Method according to one of the preceding claims, characterized in that the first magnet (1) has a magnetization, and wherein at least one second magnet (2) is provided which has a different magnetization to the first magnet and which is arranged on or in relation to the movable element at a defined distance from the first magnet (1), and to which a second magnetic field is assigned, and wherein the first magnetic field and the at least second magnetic field form a resulting total magnetic field, and wherein the Hall sensor, which is arranged relative to the at least one first magnet (1) and the second magnet (2), detects the resulting total magnetic field. Procedure according to Claim 3 , characterized in that the Hall sensor (3) measures two first different magnetic measured values and two second different magnetic measured values and two third different magnetic measured values on opposite sides of the Hall sensor (3) based on the resulting magnetic field, and wherein the respective spatial coordinate (dBx, dBy, dBz) is formed by the difference between the respective corresponding measured values, and wherein the magnetic angle (α _mag ) is formed using the atan function or the atan2 function from the first spatial coordinate (dBx) and the third spatial coordinate (dBz). Method according to one of the preceding claims, characterized in that the measurable second spatial coordinate (dBy) is generated by rotating the Hall sensor about the z-axis. Method according to one of the preceding claims, characterized in that the measurable second spatial coordinate (dBy) is generated by tilting the at least one magnet (1) about the x-axis. Method according to one of the preceding claims, characterized in that the measurable second spatial coordinate (dBy) is realized by a magnetization of the at least one magnet (1) tilted about the x-axis. Position detection system for generating a robust position signal for determining a position of a movable element, wherein the movable element is arranged in the xy plane with respect to an x,y,z coordinate system and is movable in an x-direction, comprising at least one first magnet (1) which has a magnetization and which is arranged on or in relation to the movable element and to which a first magnetic field is assigned, and at least one Hall sensor which is arranged relative to the at least one first magnet (1) for detecting the magnetic field and which is designed to generate a position signal which represents the position of the movable element along the x-direction, characterized in that the Hall sensor is designed to generate a first magnetic spatial coordinate (dBx) matched to the x,y,z coordinate system and a second magnetic spatial coordinate (dBy) and a third magnetic spatial coordinate (dBz) based on a magnetic flux density of the first magnetic field of the at least one first magnet (1), and/or wherein the Hall sensor is rotated about the z-axis is rotated with respect to the x-direction of the movable element to generate a measurable second spatial coordinate (dBy) by the Hall sensor and/or wherein the at least one first magnet (1) is tilted with respect to the x-direction of the movable element and/or its magnetization is tilted with respect to the x-direction of the movable element to generate a measurable second spatial coordinate (dBy). Position detection system according to Claim 8 , characterized in that an evaluation unit is provided for determining a first magnetic angle (α _mag ) based on the first spatial coordinate (dBx) and the third spatial coordinate (dBz) and a second magnetic angle (α _{mag , shifted ) shifted in the range of 180° in magnitude relative to the first magnetic angle (α mag} ), and wherein a storage unit is also provided with a threshold value (β) for the first magnetic angle (α _mag ), wherein the threshold value (β) is matched to the arrangement of the at least one first magnet (1) and the Hall sensor, and a calculation module is provided which is designed to use the first magnetic angle (α _mag ) as a position signal when the first magnetic angle (α _mag ) is below the amount of the threshold value (β) and which is further designed to increase the second magnetic angle (α _{mag, shifted} ) by approximately 180° when the second magnetic spatial coordinate (dBy) is positive and to use the thus shifted second magnetic angle (α _{mag, shifted} ) as a position signal and wherein the calculation module is further designed to reduce the second magnetic angle (α _{mag, shifted} ) by approximately 180° if the second magnetic spatial coordinate (dBy) is negative and to use the thus shifted second magnetic angle (α _{mag, shifted} ) as a position signal. Position detection system according to Claim 9 , characterized in that the first magnet (1) has a magnetization, and wherein at least one second magnet (2) is provided which has a different magnetization to the first magnet and which is arranged on or in relation to the movable element at a defined distance from the first magnet (1), and to which a second magnetic field is assigned, and wherein the first magnetic field and the at least second magnetic field form a resulting total magnetic field, and wherein the Hall sensor is arranged relative to the at least one first magnet (1) and to the second magnet (2) for detecting the resulting total magnetic field. Use of the method according to one of the preceding Claims 1 until 7 and/or the position detection system according to one of the preceding Claims 8 until 10 in a linear system or in an angle measuring system designed to carry out angle measurements in a limited angular range. Use according to Claim 11 , characterized in that the angle measuring system is designed for angle measurement in the range of +/- 30°.

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