Inductive position sensor

Abstract

Disclosed is a sensor (9) for detecting an angle of rotation (22) of a shaft (7, 11) and a torque angle (16) dependent on a torque acting on the shaft (7, 11), in which the shaft (7, 11) is divided into a first shaft section (11), a second shaft section (7) and a torsion element separating the first shaft section (11) and the second shaft section (7), the sensor (9) comprising: a coarse track (18) arranged circumferentially around the first shaft section (11), and having a plurality of coarse track elements (29) arranged equidistantly from each other (hereinafter represented by symbol A); -a fine track (17) arranged circumferentially around the second shaft section (7) and having a plurality of fine track elements (27) arranged equidistantly from one another (hereinafter in symbol B), the number of fine track elements being greater than the number of coarse track elements; and-a detection unit (19) configured to detect the rotation angle (22) and the torque angle (16) in accordance with the angular position (34) of the coarse track (18) and the angular position (33) of the fine track (17) within a maximum torque angle range (hereinafter, represented by symbol T) and a maximum rotation angle range (51) (hereinafter, represented by symbol S); -wherein the number of coarse track elements and the number of fine track elements are in a non-integer ratio to each other, characterized in that the number of coarse track elements and the number of fine track elements satisfy the following condition: Formula (I), i.e., where the function gcd () represents the determination of the greatest common divisor and the symbol [theta] represents a full angle measurement.

Description

Technical Field

[0001] This invention relates to a sensor for detecting the rotation angle of a shaft and a torque angle that depends on the torque acting on the shaft. The invention also relates to a method of using the sensor and a control device for performing the method. Background Technology

[0002] EP 1 081 454 A1 discloses an angle sensor comprising an oscillator circuit, multiple receiver coils, and a coarse track and a fine track in the form of movable inductively coupled elements. Angular position is evaluated using the Vernier algorithm, where the coarse and fine tracks must have different divisions. Importantly, the number of periodic repetitions of the elements of the coarse and fine tracks is a non-integer ratio to each other throughout the entire measurement range of the angle sensor. However, no specific instructions for selecting the divisions are disclosed. Summary of the Invention

[0003] The purpose of this invention is to improve the angle sensor.

[0004] This objective is achieved through the features of the independent claim. Preferred further developments are the subject of the dependent claim.

[0005] According to one aspect of the invention, a sensor is provided for detecting the rotation angle of a shaft and a torque angle depending on the torque acting on the shaft, wherein the shaft is divided into a first shaft segment, a second shaft segment, and a torsion element separating the first shaft segment and the second shaft segment, the sensor comprising: - A coarse track, arranged circumferentially around the first axis segment, and having a plurality of coarse track elements (hereinafter referred to as A) arranged equidistantly from each other. - A fine track, circumferentially arranged around the second axis segment, and having a plurality of fine track elements (hereinafter denoted by symbol B) equidistant from each other, wherein the number of fine track elements is greater than the number of coarse track elements; and - A detection unit is configured to detect the rotation angle and the torque angle based on the angular position of the coarse track and the angular position of the fine track within a maximum torque angle range (hereinafter denoted by the symbol T) and a maximum rotation angle range (hereinafter denoted by the symbol S); The number of the coarse orbital elements and the number of the fine orbital elements are in a non-integer ratio, characterized in that: The number of coarse track elements and the number of fine track elements satisfy the following condition: , The function gcd() determines the greatest common divisor, and the symbol θ represents the full angle (360°) angle measurement.

[0006] Starting with the initially mentioned sensor, the disclosed sensor is designed to integrate torque detection while using the coarse track and the fine track to determine the rotation angle.

[0007] Based on this motivation, the disclosed sensor is built upon the initial consideration that, when the torque acts on the shaft, the coarse track and the fine track are displaced relative to each other, resulting in distortion of the angular position detection. Although algorithms exist to correct such distortion, these algorithms can only operate reliably if the torque acting on the shaft remains within a torque angular limit that is not further defined.

[0008] In this regard, the disclosed sensor aims to solve this problem by bringing the coarse track and the fine track as close as possible to the torque angle limit range, which is achieved by means of the conditions according to the invention.

[0009] In a further development of the disclosed sensor, the coarse track and the fine track are configured to alter the electrical and / or magnetic properties of the space, wherein the electrical and / or magnetic properties of the space are a function of the angular positions of the coarse track and the fine track, and, in order to detect the angular positions of the coarse track or the fine track, the detection unit is configured to generate an electrical coarse track signal or a fine track signal, respectively, wherein the coarse track signal or the fine track signal depends on the electrical and / or magnetic properties of the space.

[0010] These signals can be processed in a simple manner using information technology to determine the torque and rotation angle using a torsion element with a spring stiffness assumed to be known, since the spring stiffness is freely selectable.

[0011] In a further development of the disclosed sensor, the number of fine track elements and the number of coarse track elements share a common divisor. In this way, the maximum measurable torque angle can be maximized.

[0012] In another further development of the disclosed sensor, the detection unit is configured to detect coarse orbital signal errors with electrical properties (hereinafter referred to as E). A The coarse orbit signal and the fine orbit signal error with electrical properties (hereinafter referred to as E) are the coarse orbit signal and the fine orbit signal error with electrical properties. B The fine track signal (represented by E) is selected such that the number of the coarse track elements and the number of the fine track elements are chosen such that the torque angle error (hereinafter referred to as E) is... T (This indicates that) the following conditions must be met: , The symbol C can be any real value that can be chosen.

[0013] In this way, a margin for measurement error that occurs during the detection of the torque can be taken into account. A constant E A and E B Measurement error E T The idea of ​​minimization is based on choosing A and B as large as possible. In this case, the arbitrary real value C can represent a fundamentally unknown value that describes the additional measurement error generated during the operation of the sensor.

[0014] In another further development of the disclosed sensor, the maximum rotation angle range is selected to satisfy the following condition: , Preferred .

[0015] Without using information from the satellite gears, the maximum achievable definite rotation angle S is characterized in that it is always less than or equal to a complete rotation. The maximum achievable definite rotation angle S is determined by the following formula: .

[0016] It is clear from the formula that, in order to achieve a large value of S, it is advantageous to choose A and B so that the greatest common divisor is as small as possible.

[0017] The maximum achievable definite rotation angle S is characterized in that it is greater than a full rotation of 360°, typically on the order of several full rotations of ±1000°. Since a direct proportional relationship is clearly visible in the formula, it is obviously advantageous to choose A and B such that the greatest common divisor is as small as possible in order to achieve a large maximum achievable definite rotation angle S.

[0018] Taking into account the coarse orbit signal and the fine orbit signal, as well as the measurement accuracy typically expected for the satellite gears, scaling factors of 19 and 9.5 were empirically determined.

[0019] In this way, the disclosed sensor's function of detecting the rotation angle achieves the Automotive Safety Integrity Level (ASIL) specified in standard ISO 26262 (2018), Road Vehicles – “Functional Safety, International Organization for Standardization”. ISO 26262 defines four Automotive Safety Integrity Levels (ASIL A to D), with ASIL D representing the highest safety level. Through the aforementioned conditions... When using signals from satellite gears with a hypothetical single point of failure metric (SPFM) of ≥97%, safety level ASIL C can be achieved, and by meeting the aforementioned conditions... Furthermore, when using signals from satellite gears with an SPFM assumption of ≥98%, even a safety level of ASIC D can be achieved with the help of additional diagnostics.

[0020] In another further development of the disclosed sensor, the maximum torque angle range is selected to satisfy the following condition: .

[0021] In order to achieve the maximum possible range of specific torque angles T, it is evident from the formula that A and B must be chosen such that the quotient of the product of the greatest common divisor of A and B and the product of A and B is as large as possible.

[0022] In yet another further development of the disclosed sensor, the number of the coarse orbital elements and the number of the fine orbital elements are selected from: A=9 and B=6, or A=10 and B=6, or A=12 and B=8, or A=12 and B=9, or A=15 and B=6, or A=15 and B=10, or A=18 and B=12.

[0023] Due to this selection of the number of coarse orbital elements and the number of fine orbital elements, optimal results can be achieved for the measurable torque angle range T and the measurable rotation angle range S (or SM when using the satellite gears). For the selection of A and B, T, SM, and E at the system level... T The competitive requirements necessitate choosing the combination of A and B that is most advantageous for their respective applications.

[0024] Therefore, choosing A=9 and B=6 can cover a torque angle range T of ±10°, an angle range SM of ±1140°, and a torque angle error E of ±0.16°. T .

[0025] Choosing A=10 and B=6 covers a torque angle range T of ±6°, an angle range SM of ±1710°, and a torque angle error E of ±0.15°. T .

[0026] Choosing A=12 and B=8 covers a torque angle range T of ±7.5°, an angle range SM of ±855°, and a torque angle error E of ±0.12°. T .

[0027] Choosing A=12 and B=9 covers a torque angle range T of ±5°, an angle range SM of ±1140°, and a torque angle error E of ±0.12°. T .

[0028] Choosing A=15 and B=6 covers a torque angle range T of ±6°, an angle range SM of ±1140°, and a torque angle error E of ±0.14°. T .

[0029] Choosing A=15 and B=10 covers a torque angle range T of ±6°, an angle range SM of ±684°, and a torque angle error E of ±0.10°. T .

[0030] Choosing A=18 and B=2 can cover a torque angle range T of ±5°, an angle range SM of ±570°, and a torque angle error E of ±0.09°. T .

[0031] Based on this selection, the combination of A=12 and B=9 has been proven to be the most suitable for the field of steering angle technology in vehicles.

[0032] According to another aspect of the present invention, a method for detecting the rotation angle of an axis using a disclosed sensor is provided, the method comprising the following steps: - Detect the angular position of the coarse track; - Detect the angular position of the fine track; - Based on the detected angular position of the coarse orbit, determine the number of full periods of the angular position of the fine orbit that has been traversed; and - The angular position of the fine orbit is corrected based on the number of whole cycles of the determined angular position of the fine orbit.

[0033] In a further development, the disclosed method includes the following steps: - Detect the angular position of the satellite gear; - Based on the detected angular position of the satellite gear, determine the number of integer cycles of the angular position of the traversed fine orbit; and - The angular position of the fine orbit is corrected based on the number of integer cycles of the determined angular position of the fine orbit.

[0034] According to another aspect of the present invention, a control device for performing a disclosed method is provided.

[0035] In a further development of the disclosed apparatus, the apparatus includes a memory and a processor. The disclosed method is stored in the memory as a computer program, and the processor is configured to execute the method when the computer program is loaded from the memory into the processor.

[0036] According to another aspect of the present invention, a computer program is provided, the computer program including program code means for performing all steps of the disclosed method when the computer program is executed on an electronic device or a disclosed apparatus.

[0037] According to another aspect of the present invention, a computer program product is provided, the computer program product comprising program code stored on a computer-readable data carrier, wherein when the program code is executed on a data processing device, the program code performs the disclosed method. Attached Figure Description

[0038] The above-described features, characteristics, and advantages of the present invention, as well as the ways in which they are implemented, will become more apparent from the following description of exemplary embodiments, which will be explained in more detail with reference to the accompanying drawings. The drawings are shown below: Figure 1 This is a structural diagram of a vehicle equipped with sensors for detecting rotation angle and torque; Figure 2 yes Figure 1 A structural diagram of a sensor used to detect rotation angle and torque; Figure 3 It is used for explanation Figure 2 A structural diagram showing the determination of the rotation angle in a sensor; Figure 4 yes Figure 2 and Figure 3 Time progression diagrams of coarse and fine orbit signals from the sensor; Figure 5 It originates from Figure 4 Time-course plot of the resulting position signal from the coarse and fine orbit signals; Figure 6 yes Figure 2 and Figure 3 Another position signal in the sensor and Figure 5 The time progression graph of the resulting position signal; and Figure 7 It originates from Figure 2 and Figure 3 The rotation angle signal of the other position signal in the sensor and Figure 6 The resulting position signal time progression graph. Specific Implementation In the accompanying drawings, the same technical elements are labeled with the same reference numerals and are described only once. The drawings are merely schematic and do not, in particular, represent actual geometric relationships.

[0040] First refer to Figure 1It schematically shows a perspective view of a vehicle 1 with a steering system 2.

[0041] In this exemplary embodiment, vehicle 1 includes a chassis 5 supported on two front wheels 3 and two rear wheels 4. The front wheels 3 can be steered by a steering system 2, enabling vehicle 1 to travel on curves.

[0042] The steering system 2 includes a steering wheel 6 mounted on a first steering shaft 7, which is arranged to rotate about a rotation axis 8. The first steering shaft 7 is guided to a sensor 9 for detecting position, specifically angular position, and is connected in the sensor 9 to a torsion element 10 (the connection method is not described in detail here). The torsion element has a freely selectable spring stiffness, preferably constant and linear, thereby converting the applied torque into a measurable torque angle. On the side of the torsion element 10 opposite to the first steering shaft 7, along the rotation axis 8, is a second steering shaft 11, which terminates at a steering gear 12. When the steering wheel 6 rotates with a torque in the form of a steering torque 13, the steering torque 13 is correspondingly transmitted through the steering shafts 7 and 11 to the steering gear 12, in response to which the steering gear 12 causes the front wheels 3 to turn with a wheel steering angle 14.

[0043] Steering is assisted by an auxiliary motor 15, which additionally drives the second steering shaft 11 to rotate. For this purpose, the steering torque 13 originates from the rotational angle difference 16 between the first steering shaft 7 and the second steering shaft 11, which is detected by an inductive sensor 9. The auxiliary motor 15 then drives the second steering shaft 11 to rotate, specifically as a function of the detected steering torque 13.

[0044] To detect the aforementioned rotational angle difference 16 in order to detect the steering torque 13, sensor 9 includes a fine track 17 connected to the first steering shaft 7 and a coarse track 18 connected to the second steering shaft 11, which will be discussed in more detail later. Sensor 9 also includes a measuring circuit 19, which is fixed in position relative to vehicle 1. The measuring circuit 19 detects the angular positions of the fine track 17 and the coarse track 18 and thereby determines the rotational angle difference 16. This will also be discussed in more detail later. Based on the rotational angle difference 16, control device 20 can drive auxiliary motor 15 with a suitable control signal 21.

[0045] In addition to the rotation angle difference 16, the measurement circuit 19 of sensor 9 also determines the overall rotation angle 22 of steering shafts 7, 11 for use, for example, in vehicle dynamics systems.

[0046] The following is for reference. Figure 2 The structure of the sensor 9 described in this exemplary embodiment will be described in more detail.

[0047] The coarse track 18 is directly fixed to the second steering shaft 11 by rotation, while the fine track 17 is held on the first steering shaft 7 by a support sleeve 23. An input gear 24, also fixed to the support sleeve 23 by rotation, drives the output gear 25 of the multi-angle detection device 26 in a manner described later.

[0048] In this embodiment, the fine track 17 is designed as an impeller with multiple fine track blades 27 made of metal. The individual fine track blades 27 are equidistantly distributed in a circumferential direction around the first steering shaft 7 and held on the fine track carrier 28. For further explanation, it is assumed that the number of fine track elements is twelve fine track blades 27, although in Figure 2 More fine track blades 27 are clearly shown in the image.

[0049] Similarly, the coarse track 18 in this embodiment is also designed as an impeller with multiple coarse track blades 29 made of metal. The individual coarse track blades 29 are similarly equidistantly distributed in a circumferential direction around the first steering axis 7 and, similar to the fine track 17, are held on the coarse track carrier 30. For further explanation, assume the number of coarse track elements is eight coarse track blades 29. Figure 2 Not all of these rough track blades 29 are visible in the perspective view.

[0050] Using coarse track blade 29 and fine track blade 27, measuring circuit 19 can determine rotation angle 22. For this purpose, measuring circuit 19 can be designed essentially as described in EP 3 865 824 A1.

[0051] The measuring circuit 19 has a fine track side 31 facing the fine track blade 27 and a coarse track side 32 facing the coarse track blade 29. On each side of the measuring circuit 19, a transmitting coil (not shown in further detail) and at least one receiving coil (not shown in further detail) are arranged, wherein the transmitting coil is preferably used to excite a high-frequency magnetic field, which induces a voltage in the receiving coil. Thus, on the fine track side 31, a voltage is generated in its corresponding receiving coil. Figure 3 The fine track signal 33 shown is generated in its corresponding receiving coil on the coarse track side 32. Figure 3 The rough track signal 34 shown is illustrated.

[0052] In this configuration of the measurement circuit 19, the blades 27 and 29 interfere with the magnetic fields generated by the respective transmitting coils. As a result, the fine track signal 33 and the coarse track signal 34 vary as a function of the rotation angles of the respective tracks 17 and 18. This basic configuration can be extended to, for example, make the measurement system more robust to measurement errors. Such extensions are discussed in EP 3 865 824A1, which has already been cited. However, such extensions are not necessary for understanding this embodiment.

[0053] Ultimately, to understand this embodiment, it is only necessary for the blades 27 and 29 of tracks 17 and 18 to generate track signals 33 and 34, which change periodically with the angular position of each track 17 and 18.

[0054] In addition to track signals 33 and 34, the multi-angle detection device 26 also outputs... Figure 3 The magnetic angle signal 35 is shown. The magnetic angle signal 35 is generated based on the radial magnetization magnet 36 in the magnetic sensor element 37. The radial magnetization magnet 36 is disposed on the side of the output gear 25 facing the circuit board 19 and rotates above the magnetic sensor element 37 via the output gear 25.

[0055] Then, based on track signals 33 and 34 and magnetic angle signal 35, the overall rotation angle 22 of steering shafts 7 and 11 is calculated on circuit board 19 and output through output interface 38. The following will refer to... Figures 3 to 7 The calculations described will be discussed in detail.

[0056] First, each signal 33 to 35 is converted into a sawtooth wave signal in the corresponding conversion unit, thereby obtaining a coarse track sawtooth wave signal 39, a fine track sawtooth wave signal 40, and a magnetic sawtooth wave signal 41.

[0057] Subsequently, the coarse track sawtooth wave signal 39 and the fine track sawtooth wave signal 40 are combined in the combining unit based on a suitable Vernier algorithm to form the intermediate angle signal 42.

[0058] Reference Figure 4 and 5 To explain this combination in more detail, the signal values ​​43 of each signal are qualitatively plotted with respect to the rotation angle 22 to be measured.

[0059] In this case, sawtooth wave signals 39 and 40 are generated such that their respective signal values ​​43 increase directly proportionally to the rotation angle 22, with a scaling factor of 1.

[0060] Based on the number of fine track elements in the 12 fine track blades and the number of coarse track elements in the 8 coarse track blades, the fine track sawtooth wave signal 40 has a fine track period length of 30° 44, and the coarse track sawtooth wave signal 39 has a coarse track period length of 45° 45. Since the least common multiple of these two period lengths is 90°, the intermediate angle signal 42 can be measured based on the intermediate angle period length 46 of 90° for these two sawtooth track signals 39 and 40.

[0061] To form the intermediate angle signal 42, the Bezout coefficients of the corresponding linear combination 50 of the fine orbital sawtooth wave signal 40 and the coarse orbital sawtooth wave signal 39 are 3 for the fine orbital sawtooth wave signal 40 and 2 for the coarse orbital sawtooth wave signal 39. Thus, the intermediate angle signal 42 can be formed according to this linear combination. If necessary, if the intermediate angle signal 42 is less than or equal to 0, the linear combination must have an offset of the intermediate angle period length 46. The resulting intermediate angle signal 42 is as follows: Figure 4 As shown.

[0062] However, the intermediate angle signal 42 may be distorted, especially when the torque is applied to the steering shafts 7, 11 as a whole. This will lead to measurement errors. To avoid these measurement errors, a modular division 47 is applied to the intermediate angle signal 42, with the fine track sawtooth wave signal 40 as the divisor. The quotient 48 of the modular division 47 is then multiplied by the fine track sawtooth wave signal 40, and the remainder of the modular division 47 is discarded. If the coarse track sawtooth wave signal 39 is therefore offset relative to the fine track sawtooth wave signal 40 and the intermediate angle signal 42 is therefore affected by the error, the error is filtered out by the method described above. In this context, it should be noted that the tracks 17, 18 of the sawtooth wave signals 39, 40 used as the basis for determining the corresponding correction of the intermediate angle signal 49 should be arranged on the side facing the steering wheel 6 in order to detect the steering angle 13 without error. Although the coarse track sawtooth wave signal 39 can also be used in principle for the correction method described above, the fine track sawtooth wave signal 40 inherently has higher resolution and is therefore more suitable for correction.

[0063] Finally, in a further linear combination 50, in the case of the corrected intermediate angle signal 49 and the magnetic sawtooth wave signal 41, the rotation angle 22 to be finally determined is calculated. If all the aforementioned sawtooth wave signals are generated such that the signal value 43 changes directly proportionally to the rotation angle 22, where the scaling factor is 1, then the rotation angle 22 can be directly read from the result of the second linear combination, as follows. Figure 7 As shown.

[0064] Here, the rotation angle 22 is reliably detected within an angle range of ±855° 51.

Claims

1. A sensor (9) for detecting a rotation angle (22) of a shaft (7, 11) and a torque angle (16) depending on the torque acting on the shaft (7, 11), wherein the shaft (7, 11) is divided into a first shaft segment (11), a second shaft segment (7), and a torsion element separating the first shaft segment (11) and the second shaft segment (7), the sensor (9) comprising: - A coarse track (18) is arranged circumferentially around the first shaft segment (11) and has a plurality of coarse track elements (29) arranged equidistantly from each other (hereinafter referred to as A). - Fine track (17), circumferentially arranged around the second axis segment (7), and having a plurality of fine track elements (27) (hereinafter referred to as B) arranged equidistantly from each other, wherein the number of fine track elements is greater than the number of coarse track elements; as well as - The detection unit (19) is configured to detect the rotation angle (22) and the torque angle (16) based on the angular position (34) of the coarse track (18) and the angular position (33) of the fine track (17) within the maximum torque angle range (hereinafter referred to as T) and the maximum rotation angle range (51) (hereinafter referred to as S). - The number of the coarse orbital elements and the number of the fine orbital elements are non-integer ratios between each other. Its features are: The number of coarse track elements and the number of fine track elements satisfy the following condition: ， The function gcd() determines the greatest common divisor, and the symbol θ represents the full angle measurement.

2. The sensor (9) according to claim 1, wherein the number of the coarse track elements and the number of the fine track elements have a common divisor.

3. The sensor (9) according to claim 1 or 2, wherein the coarse track (18) and the fine track (17) are configured to change the electrical and / or magnetic properties of the space, wherein the electrical and / or magnetic properties of the space are a function of the angular positions (34, 33) of the coarse track (18) and the fine track (17), and wherein, In order to detect the angular position (34, 33) of the coarse track (18) or the fine track (17), the detection unit (19) is configured to generate an electrical coarse track signal (39) or a fine track signal (40), respectively, wherein the coarse track signal (39) or the fine track signal (40) depends on the electrical and / or magnetic properties of the space.

4. The sensor (9) according to claim 3, wherein the detection unit (19) is configured to detect a coarse orbital signal error having electrical characteristics (hereinafter referred to as E). A The coarse orbit signal (39) and the fine orbit signal error (hereinafter referred to as E) are represented by the symbol E. B The fine track signal (40) is represented by the coarse track element, and the number of the coarse track element and the number of the fine track element are selected such that the torque angle error (16) (hereinafter referred to as E) is equal to the torque angle error (16). T (This indicates that) the following conditions must be met: ， The symbol C can be any real value that can be chosen.

5. The sensor (9) according to any one of the preceding claims, wherein, The maximum rotation angle range (51) is selected to satisfy the following conditions: ， Preferred .

6. The sensor (9) according to any one of the preceding claims, wherein, The maximum torque angle range (51) is selected to satisfy the following conditions: 。 7. The sensor (9) according to any one of the preceding claims, wherein, The number of coarse track elements and the number of fine track elements are selected from: - A=9 and B=6, or - A=10 and B=6, or - A=12 and B=8, or - A=12 and B=9, or - A=15 and B=6, or - A=15 and B=10, or - A=18, B=12.

8. A method for detecting the rotation angle (22) of an axis (7, 11) using a sensor (9) according to any one of the preceding claims, the method comprising: - Detect the angular position (34) of the coarse track (18); - Detect the angular position (33) of the fine track (17); - Based on the angular position (34) of the detected coarse orbit (18), determine the number of integer cycles (44) of the angular position (33) of the fine orbit (17) that have been traversed; and - Based on the number of whole cycles (44) of the determined angular position (33) of the fine orbit (17), the angular position (33) of the fine orbit (17) is corrected.

9. The method according to claim 8, wherein, The angular position (33) of the fine orbit (17) is added to a determined number of integer periods (44) in order to correct the angular position (33) of the fine orbit (17).

10. A control device (19) for performing the method according to any one of the preceding claims.

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