Method and detection system for detecting an angular position

Abstract

The present invention relates to a method (100) for detecting the angular position (α) of a rotating member (22) rotatable about a rotation axis (24) via a sensor unit (26), the sensor unit having a fixed sensor element (30) and a rotating element (28) rotatable relative to the sensor element and co-rotating with the rotating member (22), wherein the sensor element (30) outputs first and second sensor signals (S1, S2) related to the angular position to an evaluation unit (102), from which the evaluation unit calculates an angular signal and an angular error (ε) describing the angular position. The angular signal describes the angular position, wherein the orthogonal error (φ), which describes the orthogonal deviation between the first sensor signal and the second sensor signal (S1, S2) and is associated with the angular error (ε), is calculated by: detecting the first angular gradient (G1) of the angular signal in the first rotational position of the rotating member (22), and detecting the second angular gradient (G2) of the angular signal in the second rotational position of the rotating member (22) different from the first rotational position; then calculating the orthogonal error (φ) in relation to the first angular gradient and the second angular gradient (G1, G2); and further, calculating the angular position (α) f The orthogonal error (φ) is eliminated. Furthermore, the present invention relates to a detection system.

Description

TECHNICAL FIELD

[0001] The invention relates to a method for detecting an angular position according to the preamble of claim 1. Furthermore, the invention relates to a detection system for detecting an angular position. BACKGROUND

[0002] A method for detecting an angular position of a rotary member is known, for example, from WO 2018 / 219388 A1. Therein, a method for detecting an angular position of a rotary member rotatable about a rotary axis is described, in which the angular position of the rotary member is received by a sensor device arranged radially spaced apart from the rotary axis. A magnet ring fixedly and concentrically arranged at the rotary member causes a varying magnetic field relative to the sensor device, which is detected by the sensor device, wherein the signals received by the sensor device are evaluated with respect to the angular position. The signals received by the sensor device are evaluated with respect to amplitude information of the magnetic field and a correction parameter is derived from the amplitude information, by means of which an angular error of the angular position received from the signals of the sensor device is determined. The angular error is then used to correct the angular position derived from the signals output by the sensor device. SUMMARY

[0003] It is an object of the invention to detect an angular position of a rotary member more precisely and more quickly. The angular position of the rotary member should be derivable with as little computational effort as possible. Furthermore, the detection of the angular position should be more cost- effectively performed.

[0004] At least one of the objects is achieved by a method for detecting an angular position of a rotary member rotatable about a rotary axis via a sensor unit, the sensor unit having a fixed sensor element and a rotary element rotatable relative to the sensor element and in common with the rotary member, wherein the sensor element outputs a first sensor signal and a second sensor signal related to the angular position to an evaluation unit, from which an angular signal describing the angular position and an angular error are calculated, wherein an orthogonal error associated with the angular error, describing an orthogonal deviation between the first sensor signal and the second sensor signal, is calculated in that a first angular gradient of the angular signal is detected in a first rotary position of the rotary member and a second angular gradient of the angular signal is detected in a second rotary position of the rotary member deviating from the first rotary position, the orthogonal error is then calculated in relation to the first angular gradient and the second angular gradient, and the orthogonal error is furthermore eliminated for the angular position.

[0005] Thereby, the angular position of the rotary member can be detected more precisely. Measurement errors can be reduced with little computational effort.

[0006] The orthogonal error can be caused by a tilt of the rotary member about the rotary axis.

[0007] The sensor unit and the rotary member can be provided in a vehicle. The rotary member can be associated with a parking lock device. The parking lock device can have a parking lock actuator with the rotary member. The parking lock actuator can have an electric motor with a stator and a rotor rotatable relative thereto. The rotary member can be connected to the rotor against rotation. The electric motor can be connected to the hydraulic pump in a driving manner. The sensor unit can detect an angular position of the rotor relative to the stator. Thereby, commutation of the electric motor can be improved.

[0008] The rotary member can be provided at an actuator for operating a clutch of a vehicle.

[0009] The rotary member and the rotary element can be concentrically rotatably provided.

[0010] The sensor unit can be configured as an angle sensor.

[0011] The sensor elements can be Hall sensors. The sensor unit can have at least two sensor elements. The sensor unit can have four sensor elements.

[0012] The rotary element can be a ring of magnets. The rotary element can be a permanent magnet. The rotary element can be diagonally magnetized.

[0013] The sensor unit can output a first sensor signal associated with a first detection position and a second sensor signal associated with a second detection position around the rotary axis perpendicular to the first detection position. The sensor elements can be arranged radially offset from the rotary axis. Thereby, the first sensor signal and / or the second sensor can be a periodic signal, in particular caused by a rotation of the rotary element. The first sensor signal can be a cosine signal and the second sensor signal can be a sine signal.

[0014] The angle signal can be calculated from the first sensor signal and the second sensor signal by applying an atan2 function. The proposed method can then be performed.

[0015] The angle error can have an amplitude error describing an amplitude difference between the first sensor signal and the second sensor signal and / or an offset error. These errors can have been reduced or eliminated before calculating the quadrature error. The first sensor signal and the second sensor signal can have eliminated possible offset errors and / or possible amplitude errors before applying the proposed method, for example by using a max-min method.

[0016] The proposed method can be performed in a vehicle during operation of the application side of the rotary member. The angle signal can be smoothed with a smoothing average method before detecting the first angular gradient and the second angular gradient.

[0017] In a preferred embodiment of the application it is advantageous to detect the first angle gradient and the second angle gradient by rotating the rotating member at a constant rotational speed. The rotating member can be free of a driving torque. During the detection of the first angle gradient and the second angle gradient the moment of inertia of the members involved in the rotational movement, including the rotating member, can cause a constant rotational speed which is almost constant with a deviation of less than 10%, in particular less than 5%, particularly preferably less than 1%.

[0018] The angle gradient G* can be calculated as follows:

[0019]

[0020] If the first angle gradient and the second angle gradient are detected at a constant rotational speed, the angle gradient G can be calculated simply according to

[0021] G = Δα

[0022]

[0023] If the angle gradient is calculated according to the correlation, the calculation effort and the numerical noise occurring with division can be reduced.

[0024] In a preferred embodiment of the application it is advantageous to detect the first angle gradient and the second angle gradient by rotating the rotating member, in particular around the rotational axis, through at least 90°. Thereby, the second measurement value can be detected and at the same time the method can be performed more quickly. The rotating member can be rotated through at least one full revolution in order to detect the first angle gradient and the second angle gradient.

[0025] In a preferred embodiment of the application it is advantageous for the first rotational position to be at 45° and the second rotational position to be at 135°. The first angle gradient G1 can be detected at 135° and the second angle gradient G2 can be detected at 45°.

[0026] The following preferred design of the application is advantageous, in which an error parameter is calculated in relation to the quotient of the first angle gradient and the second angle gradient. The error parameter γ can be calculated as follows:

[0027]

[0028] In a preferred embodiment of the application it is advantageous to calculate the orthogonal error in relation to the error parameter γ. The orthogonal error

[0029]

[0030] In a particular design of the application it is advantageous to calculate the angle error in relation to the orthogonal error​ angular error can be calculated as follows:

[0031]

[0032] In the case of small orthogonal errors the correlation (1) can be simplified to:

[0033]

[0034] In a preferred embodiment of the application it is proposed to subtract the angular error

[0035]

[0036] At least one of the objects set forth above is further achieved by a detection system for detecting the angular position of a rotating member by the method given above, said detection system having an evaluation unit and a sensor unit, said sensor unit having a stationary sensor element and a rotating element which is rotatable relative to said sensor element and jointly with the rotating member.

[0037] In an advantageous embodiment of the application it is proposed that the detection system is associated with a parking lock device.

[0038] Further advantages and advantageous design of the application result from the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0039] The application is described in detail below with reference to the drawings. Specifically shown is:

[0040] Figure 1 A cross section of a parking lock actuator with a detection system of a specific embodiment of the application is shown.

[0041] Figure 2 A flow chart of a method of a specific embodiment of the application is shown.

[0042] Figure 3 A change curve of a measured and ideal angular signal is shown.

[0043] Figure 4 An angular gradient in said change curve with respect to the rotational position is shown.

[0044] Figure 5 A change curve of the angular error with respect to the rotational position is shown.

[0045] Figure 6 A comparison of compensation powers in the calculation of the angular position is shown. DETAILED DESCRIPTION

[0046] Figure 1 A cross section of a parking lock actuator 10 of a detection system having a particular embodiment of the application is shown. The parking lock actuator 10 is preferably an electronic parking lock actuator 10 and is provided in a vehicle for operating a parking lock device. Here, the parking lock device can be switched between a locking position in which a parking position of the vehicle is fixed and a release position in which the vehicle is movable. The switching takes place via the parking lock actuator 10, which for this purpose has an electric motor 12 having a stator 14 and a rotor 16 which is movable relative to the stator.

[0047] The rotor 16 is connected to a hydraulic pump 20 via a drive shaft 18 in order to transmit a drive torque. Rotational movements of the rotor 16 are transmitted to the hydraulic pump 20, which thereby causes a change in fluid pressure in order to control the parking lock device. The drive shaft 18 can be rotated about an axis of rotation 24 as a rotational member 22 and the angular position of the rotational member 22 can be detected via a sensor unit 26.

[0048] The sensor unit 26 has a rotational element 28 which is fixedly connected to the rotational member 22. The rotational element 28 is fixedly connected to the drive shaft 18 and is preferably embodied as an angularly magnetized permanent magnet. The sensor unit 26 furthermore comprises a sensor element 30 which is connected to a housing 32 axially relative to the rotational element 28. The rotational element 28 is here rotatable relative to the sensor element 30. The sensor element 30 preferably comprises Hall sensors which are arranged radially offset from the rotational axis and which identify the angular position of the rotational member 22 via a magnetic field provided by the rotational element.

[0049] The sensor element 30 here preferably has two sensor members which are located in one plane and are perpendicular to one another and are each radially offset from the axis of rotation, the normal to the plane being parallel to the axis of rotation 24. In an ideal case, the sensor signals are periodic signals which are offset by 90° relative to one another in the case of rotational movements of the rotational member 22.

[0050] Figure 2 A flow chart of a method 100 in a particular embodiment of the application is shown. The following description refers to Figure 2 , however, partly to other figures in detail, so that the other figures are explained.

[0051] The sensor unit 26 outputs a first sensor signal S1 and a second sensor signal S2 which is ideally 90° out of phase with the first sensor signal, i.e. ideally orthogonal. For example, the first sensor signal S1 is a cosine signal and the second sensor signal S2 is a sine signal. The first and second sensor signals S1, S2 are received by the evaluation unit 102 and processed therein into an angular position a of the rotary member f . Preferably, the angular position a f is calculated from the first and second sensor signals S1, S2 via an atan2 function. The atan2 function is an extension of the inverse trigonometric function arctangent and as such is the inverse function of the trigonometric function tangent. It has two real numbers as arguments, in contrast to the conventional arctangent which has only one real number for the argument. By this, the atan2 has enough information to be able to output a function value in the value range of 360°, i.e. in all four quadrants, and does not have to be limited to two quadrants as the conventional arctangent.

[0052] The angular position a f may have an angular error here. For example, the first and second sensor signals S1, S2 can be out of phase with each other by a phase value which is not equal to 90°. A deviation from the orthogonal position of the first and second sensor signals S1, S2 causes an orthogonality error as an error component in the angular error of the angular position a f .

[0053] The method 100 described in more detail below is preferably designed for reducing or compensating for the orthogonality error. First, the rotary member is rotated by at least 90° while the rotational speed is kept as constant as possible. The setting of the rotational speed can be effected, for example, by decoupling the rotary member from the drive torque and allowing it to rotate freely. The rotational speed can be maintained almost constant temporarily by the moment of inertia of the rotary member and the components which are rotationally effectively connected thereto.

[0054] During the rotational movement, the angular position a f detected by the sensor unit 26 and output by the evaluation unit 102 is recorded as an angular signal. Before starting the atan2 function, the angular signal can eliminate possible amplitude errors and / or possible offset errors, for example by applying a max-min method.

[0055] In Figure 3 , a change curve of the angular position a with respect to the rotational position D of the rotary member is shown in a comparison between the measured angular signal a f and an ideal angular signal a t which has no orthogonality error. It can be seen that the orthogonality error causes a periodic change in the ideal angular signal a t . For example, the orthogonality error can occur due to a tilt of the rotary member about the rotational axis.

[0056] Back to Figure 2 Let the rotating member rotate at least 90°, preferably one full revolution. Subsequently, in a calculation step 104, the gradient of the angle signal is detected as the respective angle gradient at the two measuring positions. The first angle gradient Gl is preferably prescribed at 135° and the second angle gradient G2 is preferably prescribed at 45°.

[0057] In Figure 4 The angle gradient G is plotted in relation to the rotational position D of the rotating member. The angle gradient G measured over one full revolution m is preferably determined via a smoothing average method in order to reduce the influence of noise. The determined angle gradient G p is preferably continued to be used. It can be determined here that the minimum angle gradient exists at 45° and the maximum angle gradient exists at 135°.

[0058] Back to Figure 2 , the first and second angle gradients Gl, G2, i.e. the angle gradient existing at 45° and the angle gradient existing at 135°, are subsequently passed to a preparation step 106 in which an error parameter γ is calculated in relation to the quotient of the first and second angle gradients Gl, G2.

[0059] The error parameter γ is forwarded to a subsequent processing step 108 in which the quadrature error of the angle signal is calculated from it. In a subsequent conversion step 110, the quadrature error b is converted into a calculated angle error ε f , which is forwarded to a downstream output step in which the measured angle position α b is eliminated by the calculated angle error ε and output as the calculated angle position α.

[0060] The calculation step 104, the preparation step 106 and the conversion step 110 can be executed in a training process or learning process and can call up the quadrature error for example, the training process and / or the learning process can be executed before and / or during the operation of the application side of the rotating member, for example in a vehicle. The conversion step 110 can call up the trained quadrature error during the operation of the application side of the rotating member and process it as described.

[0061] Figure 5 The curve of the angle error ε in relation to the rotational position D is shown. The angle error ε of the measured angle signal m stretches periodically due to the contained quadrature error. By means of the method described above, the calculated angle error ε bThe angular error in the angle signal is thus reduced to a residual angular error ε r .

[0062] Figure 6 The comparison of the compensation of the power A when calculating the angular position is shown in Figure 6 a). The angular error ε is shown in relation to the quadrature error . The angular error ε of the measured angle signal m is greater than the residual angular error ε r when the proposed method is applied. The smaller the quadrature error , the greater the relative difference.

[0063] Figure 6 b) shows the compensation power A for the error compensation for calculating the angular position. In the case of a small quadrature error , the error compensation is maximally possible. Since the quadrature error actually expected is usually less than 20°, the compensation power A itself is thus greater than 90% here.

[0064] Legend of the figures

[0065] 10 parking lock actuator

[0066] 12 electric motor

[0067] 14 stator

[0068] 16 rotor

[0069] 18 drive shaft

[0070] 20 hydraulic pump

[0071] 22 rotary member

[0072] 24 rotary axis

[0073] 26 sensor unit

[0074] 28 rotary element

[0075] 30 sensor element

[0076] 32 housing

[0077] 100 method

[0078] 102 evaluation unit

[0079] 104 calculation step

[0080] 106 preparation step

[0081] 108 processing step

[0082] 110 conversion step

[0083] S1 first sensor signal

[0084] S2 second sensor signal

[0085] a calculated angular position

[0086] a f angular position

[0087] a t angular position

[0088] D rotational position

[0089] G angular gradient

[0090] G m measured angular gradient

[0091] G p calculated angular gradient

[0092] G1 first angular gradient

[0093] G2 second angular gradient

[0094] γ error parameter orthogonal error ε angular error ε b calculated angular error

Claims

1. A method (100) for detecting the angular position (α) of a rotating member (22) rotatable about a rotation axis (24) via a sensor unit (26), said sensor unit having a fixed sensor element (30) and a rotating element (28) rotatable relative to said sensor element and co-rotating with said rotating member (22), wherein The sensor element (30) outputs a first sensor signal and a second sensor signal (S1, S2) related to the angular position to the evaluation unit (102), from which the evaluation unit calculates the angular signal and the angular error (ε). The angular signal indicates the angular position. Its features are, The orthogonal error (φ), which describes the orthogonal deviation between the first sensor signal and the second sensor signal (S1, S2) and is associated with the angular error (ε), is calculated as follows: The first angular gradient (G1) of the angular signal is detected in the first rotational position of the rotating member (22), and the second angular gradient (G2) of the angular signal is detected in the second rotational position of the rotating member (22) different from the first rotational position. The orthogonality error (φ) is then calculated in relation to the first angular gradient and the second angular gradient (G1, G2), and Furthermore, regarding the angular position (α) f Eliminate the orthogonal error (φ).

2. The method (100) according to claim 1, Its features are, The first angular gradient (G1) and the second angular gradient (G2) are detected by rotating the rotating member (22) at a constant rotational speed.

3. The method (100) according to claim 2, Its features are, The first angular gradient (G1) and the second angular gradient (G2) are detected by rotating the rotating member (22) by at least 90°.

4. The method (100) according to claim 3, Its features are, The first rotation position is at 45° and the second rotation position is at 135°.

5. The method (100) according to any one of the preceding claims, Its features are, The error parameter (γ) is calculated in relation to the quotient of the first angular gradient and the second angular gradient (G1, G2).

6. The method (100) according to claim 5, Its features are, The orthogonal error (φ) is calculated in relation to the error parameter (γ).

7. The method (100) according to claim 6, Its features are, The angular error (ε) is calculated in relation to the orthogonality error (φ). b ).

8. The method (100) according to claim 7, Its features are, From the measured angular position (α) f Subtract the angular error (ε) from the original value. b ).

9. A detection system for detecting the angular position (α) of a rotating member (22) by means of the method (100) according to any one of the preceding claims and having an evaluation unit (102) and a sensor unit (26), the sensor unit having a fixed sensor element (30) and a rotating element (28) rotatable relative to the sensor element and together with the rotating member (22).

10. The detection system according to claim 9, Its features are, The detection system is associated with the parking lock device.

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