Guidance position sensor
The sensor design with specific track element ratios minimizes measurement errors for torque and rotation angle detection, ensuring accurate measurements across multiple rotations and meeting automotive safety standards.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- PHARMA BONES INC
- Filing Date
- 2024-07-01
- Publication Date
- 2026-07-21
AI Technical Summary
Existing angle sensors fail to provide accurate torque and rotation angle measurements across a wide range due to the relative displacement of coarse and fine tracks under torque, and existing correction algorithms are unreliable beyond a known torque limit.
A sensor design with a first and second shaft portion, each circumferentially arranged with coarse and fine tracks, respectively, where the ratio of track elements satisfies specific conditions to minimize measurement errors, allowing for accurate torque and rotation angle detection within a large range.
The sensor achieves accurate torque and rotation angle detection up to several full rotations with minimized measurement errors, meeting automotive safety integrity levels ASIL C and D, and is applicable in steering angle technology for vehicles.
Smart Images
Figure 2026524199000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a sensor for detecting a torque angle that depends on the rotational angle of a shaft and the torque acting on the shaft, a method using the sensor, and a control device for implementing the method.
Background Art
[0002] From European Patent Publication No. 1081454, an angle sensor is known that includes an oscillation circuit, a plurality of receiving coils, and both a coarse track and a fine track in the form of a movable inductive coupling element. The angular position is evaluated by applying a Vermeer algorithm, in which the distinction between the coarse track and the fine track needs to be different. Over the entire measurement range of the angle sensor, it is important that the number of periodic repetitions of the elements of the coarse track and the fine track is a ratio that is not an integer to each other. However, no specific instructions for selecting the distinction are given.
Summary of the Invention
Problems to be Solved by the Invention
[0003] An object of the present invention is to improve the angle sensor.
Means for Solving the Problems
[0004] This object is achieved by the features of the independent claims. Preferred further developments are the subject matter of the dependent claims. [[ID=,33]]
[0005] According to one aspect of the present invention, there is provided a sensor for detecting a torque angle that depends on the rotational angle of a shaft and the torque acting on the shaft, the shaft being divided into a first shaft portion, a second shaft portion, and a torsion element separating the first shaft portion and the second shaft portion, the sensor Arranged circumferentially around the first shaft portion, and denoted by the symbol A below, are a coarse track having a large number of coarse track elements, arranged at equal distances from each other. Arranged circumferentially around the second shaft section, and denoted by the symbol B below, fine tracks are arranged at equal distances from each other and have a greater number of fine track elements than the number of coarse track elements. The system includes a detection unit configured to detect rotation angle and torque angle within the maximum torque angle range indicated by symbol T and the maximum rotation angle range indicated by symbol S, based on the angular positions of the coarse and fine tracks. In a sensor where the ratio of the number of coarse track elements to the number of fine track elements is not an integer, The number of coarse track elements and the number of fine track elements are as follows:
number
[0006] Starting with the sensor mentioned at the beginning, the disclosed sensor is based on the motivation to integrate torque detection, while using both coarse and fine tracks to determine the rotation angle.
[0007] Based on this motivation, the disclosed sensor is based on the preliminary consideration that when torque is applied to the shaft, the coarse and fine tracks will be displaced relative to each other, thereby causing erroneous detection of the angular position. Algorithms to correct such errors already exist, but these algorithms only work reliably if the torque acting on the shaft remains within the torque angle limit that is no longer known.
[0008] At this point, the disclosed sensor addresses this problem with the idea of bringing the coarse and fine tracks as close as possible to this torque angle limit, which is achieved by the conditions of the present invention.
[0009] In further developed forms of the disclosed sensors, coarse tracks and fine tracks are configured to modify the electrical and / or magnetic properties of space as a function of their relative angular positions, and a detection unit for detecting the angular position of the coarse or fine track is configured to generate an electrical coarse track signal or a fine track signal, respectively, that depends on the electrical and / or magnetic properties of space.
[0010] These signals can be processed in a simple manner from an information technology perspective, and the torque can be determined using a torsional element with a spring stiffness that is assumed to be known and freely selectable, as well as the rotation angle.
[0011] In further development examples of the disclosed sensor, the number of fine track elements and the number of coarse track elements have a common common denominator. In this way, the maximum measurable torque angle can be maximized.
[0012] In a further developed form of the disclosed sensor, the detection unit is configured to detect a coarse track signal having an electrical coarse track signal error indicated below by the symbol EA, and a fine track signal having an electrical fine track signal error indicated below by the symbol EB, where the number of coarse track elements and the number of fine track elements are subject to the following conditions: the torque angle error, referred to below by the symbol ET, is subject to the following conditions
number
[0013] In this way, a margin can be considered for the measurement error that occurs during torque detection. The idea of minimizing the measurement error ET for the constants EA and EB is based on selecting A and B to be as large as possible. In this context, any real value C represents a basically unknown value that describes a further measurement error that occurs during the operation of the sensor.
[0014] In another further development example of the disclosed sensor, the range of the maximum rotation angle is selected to satisfy the following conditions
Number
Number
[0015] A definite maximum rotation angle S that can be achieved without using information from the satellite gear is always characterized by being less than one full rotation. This is determined by the following
Number
[0016] It is clear from the formula that in order to achieve a large value of S, it is advantageous to select A and B such that the greatest common divisor is as small as possible.
[0017] A definite maximum rotation angle S that can be achieved is characterized by being greater than one full rotation of 360° and typically on the order of several full rotations of ±1000°. From the obvious proportionality in the formula, it is clear that in order to increase the maximum rotation angle S that can be achieved, it is advantageous to select A and B such that the greatest common divisor is as small as possible.
[0018] The scaling factors 19 and 9.5 are determined empirically taking into account the coarse track signal and the fine track signal, and the measurement accuracy typically expected for the satellite gear.
[0019] In this way, the function of detecting the rotation angle of the disclosed sensor can achieve the automotive safety integrity level (ASIL) defined in the "Functional Safety" standard ISO 26262 (2018) of the International Organization for Standardization. The ISO 26262 standard defines four automotive safety integrity levels (ASIL A - D), and ASIL D represents the highest safety integrity level. When
Number
Number
[0020] In another further development example of the disclosed sensor, the maximum torque angle range is selected to satisfy the following conditions.
Number
[0021] It is clear from the formula that to achieve the maximum torque angle range T that is as clear as possible, it is necessary to select A and B such that the quotient 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 development example of the disclosed sensor, 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 and B = 12.
[0023] Selecting the number of coarse and fine track elements in this way yields the best results in terms of the measurable torque angle range T and the measurable rotation angle range S (or SM if using satellite gears). Regarding the selection of A and B, due to the conflicting system-level requirements of T, SM, and ET, it is necessary to select the combination of A and B that is most advantageous for each application.
[0024] Therefore, for selections A=9 and B=6, a torque angle range T of ±10°, an angle range SM of ±1140°, and a torque angle error ET of ±0.16° can be covered. When A=10 and B=6, a torque angle range T±6°, angle range SM±1710°, and torque angle error ET±0.15° can be covered.
[0025] For selections A=12 and B=8, the torque angle range T can cover ±7.5°, the angle range SM can cover ±855°, and the torque angle error ET can cover ±0.12°. For selections A=12 and B=9, the torque angle range T can cover ±5°, the angle range SM can cover ±1140°, and the torque angle error ET can cover ±0.12°.
[0026] For selections A=15 and B=6, the torque angle range T can cover ±6°, the angle range SM can cover ±1140°, and the torque angle error ET can cover ±0.14°. For selections A=15 and B=10, the torque angle range T can cover ±6°, the angle range SM can cover ±684°, and the torque angle error ET can cover ±0.10°.
[0027] For selections A=18 and B=12, the torque angle range T can cover ±5°, the angle range SM can cover ±570°, and the torque angle error ET can cover ±0.09°. This selection proves that the combination of A=12 and B=9 is the most suitable in the field of steering angle technology for vehicles.
[0028] According to a further aspect of the present invention, a method for detecting the rotation angle of a shaft using one of the disclosed sensors is: A process for detecting the angular position of a rough track, A process for detecting the precise angle position of the track, A process of determining the length of multiple time periods over which the angular positions of the finer tracks have already passed, based on the detected angular positions of the coarse tracks, The process includes correcting the angular position of the fine tracks based on the number of determined period lengths for the angular position of the fine tracks.
[0029] In further developmental examples, the disclosed method includes the following steps: A process for detecting the angular position of the satellite gear, A step of determining the number of time lengths over which the angular position of the fine track has already passed, based on the detected angular position of the satellite gear, A process for correcting the angular position of fine tracks based on the number of determined period lengths for the angular position of fine tracks.
[0030] According to a further aspect of the present invention, the control device is configured to perform one of the disclosed methods.
[0031] In a further development of the disclosed control device, the control device comprises memory and a processor. The disclosed method is stored in memory in the form of a computer program, and the processor is configured to execute the method when the computer program is loaded from memory into the processor.
[0032] According to a further aspect of the present invention, the computer program comprises program code means for performing all steps of the disclosed method when the computer program is executed on an electronic control device or on one of the disclosed control devices.
[0033] According to a further aspect of the present invention, a computer program product comprises program code stored on a computer-readable data carrier, which, when executed on a data processing device, performs the disclosed method. [Brief explanation of the drawing]
[0034] The characteristics, features, and advantages of the present invention described above, as well as the methods by which they are achieved, will become more apparent in conjunction with the following description of exemplary embodiments, which will be explained in more detail with reference to the drawings. [Figure 1] This is a structural diagram of a vehicle equipped with sensors that detect rotation angle and torque. [Figure 2] Figure 1 shows the structure of the sensor used to detect rotation angle and torque. [Figure 3] This is a structural diagram showing the determination of the rotation angle in the sensor shown in Figure 2. [Figure 4] Figures 2 and 3 show the temporal progression of coarse and fine track signals in the sensors shown. [Figure 5] Figure 4 shows the temporal progression of position signals obtained from coarse and fine track signals. [Figure 6] Figures 2 and 3 show the temporal progression of the position signals in the sensors, and Figure 5 shows the resulting position signals. [Figure 7] Figures 2 and 3 show the temporal progression of the rotation angle signal derived from the additional position signals in the sensors, and Figure 6 shows the resulting position signal. [Modes for carrying out the invention]
[0035] In drawings, identical technical elements are indicated by the same reference numeral and are described only once. Drawings are purely schematic and do not, in particular, represent actual geometric relationships.
[0036] First, refer to Figure 1, which schematically shows a perspective view of vehicle 1 equipped with the control system 2. In this embodiment, the vehicle 1 comprises a chassis 5 supported by two front wheels 3 and two rear wheels 4. The front wheels 3 can be steered via a steering system 2, allowing the vehicle 1 to navigate curves.
[0037] The control system 2 includes a control handle 6, which is mounted on a first control shaft 7 that is rotatably positioned around a pivot axis 8. The first control shaft 7 is guided to a sensor 9 for detecting position, which here takes the form of an angular position, and is connected to a torsion element 10 in a manner not further described.
[0038] The torsional element has a freely selectable spring stiffness, which is preferably selected to be constant and linear, so that the applied torque is converted into a torque angle that can be detected by measurement. On the side of the torsional element 10 facing the first steering shaft 7, the second steering shaft 11 is adjacent along the rotation axis 8 and terminates at the steering gear 12.
[0039] When the steering handle 6 rotates with torque in the form of steering torque 13, the steering torque 13 is transmitted accordingly to the steering gear 12 via the steering shafts 7 and 11, which in turn steers the front wheels 3 to a wheel steering angle 14 for cornering.
[0040] The steering operation is assisted by an auxiliary motor 15, which further rotates the second steering shaft 11. For this purpose, the steering torque 13 is derived from the difference 16 in rotation angles between the first steering shaft 7 and the second steering shaft 11, and this difference in rotation angles is detected by an inductive sensor 9. The auxiliary motor 15 then rotates the second steering shaft 11, in particular in response to the detected steering torque 13.
[0041] To detect the aforementioned difference in rotation angle 16, and consequently the steering torque 13, the 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. These will be explained in more detail later.
[0042] The sensor 9 is further fixed in position relative to the vehicle 1 and includes a measuring circuit 19 that detects the angular position of the coarse track 18 as well as the fine track 17, and determines the difference 16 in rotation angle from the angular position. This will be described in more detail at a later time. Based on the difference 16 in rotation angle, the control unit 20 can then actuate the auxiliary motor 15 with an appropriate control signal 21.
[0043] In addition to the difference in rotation angle 16, the measurement circuit 19 of the sensor 9 further determines the rotation angle 22 of the entire steering shaft 7, 11, which is used, for example, in a vehicle dynamics system. The configuration of the sensor 9, which forms the basis for the description of this embodiment, will be explained in detail below with reference to Figure 2. The coarse track 18 is fixed in the rotational direction and directly attached to the second control shaft 11, while the fine track 17 is held on the first control shaft 7 via a carrier sleeve 23. The input gear 24 is also fixed in the rotational direction to this carrier sleeve 23 and drives the output gear 25 for the multi-angle detection device 26, as will be described later.
[0044] In this embodiment, the fine track 17 is designed as an impeller having a number of metal fine track blades 27. Each fine track blade 27 is distributed equidistant circumferentially around the first steering shaft 7 and is held on a fine track carrier 28. For further explanation, Figure 2 shows a number of fine track blades 27, but a fine track number of 12 fine track blades 27 is assumed.
[0045] Similarly, the coarse track 18 in this embodiment is also designed as an impeller having a number of metal coarse track blades 29. Each individual coarse track blade 29 is similarly distributed equidistantly in the circumferential direction around the first steering shaft 7 and, like the fine track 17, is held on the coarse track carrier 30. For further explanation, a coarse track number of eight coarse track blades 29 is assumed. Not all of these coarse track blades 29 are visible in the perspective view of Figure 2.
[0046] Using coarse track blades 29 and fine track blades 27, the measuring circuit 19 can determine the rotation angle 22. For this purpose, the measuring circuit 19 can, in principle, be designed as described in European Patent Publication No. 3865824.
[0047] The measurement circuit 19 has a fine track side 31 facing the fine track vanes 27 and a coarse track side 32 facing the coarse track vanes 29. On both sides of the measurement circuit 19 are a transmitting coil (not shown in more detail) which is preferably used to excite a high-frequency magnetic field, and at least one receiving coil (not shown in more detail) on which a voltage is induced by the magnetic field. On the fine track side 31, the fine track signal 33 shown in Figure 3 is generated in the corresponding receiving coil, while on the coarse track side 32, the coarse track signal 34 shown in Figure 3 is generated in the corresponding receiving coil.
[0048] In this configuration of the measurement circuit 19, the track vanes 27 and 29 disturb the magnetic fields generated by their respective transmitting coils, resulting in fine track signals 33 and coarse track signals 34 changing as a function of the rotation angles of the respective tracks 17 and 18. This basic configuration can be extended, for example, to make the measurement system more robust to measurement errors. Such extensions are described in the previously cited European Patent Publication No. 3865824. However, such extensions are not essential for understanding this embodiment.
[0049] Ultimately, to understand the embodiment, it is only important that the track vanes 27, 29 of tracks 17, 18 generate track signals 33, 34 that change periodically with the angular position of each track 17, 18.
[0050] In addition to track signals 33 and 34, the multi-angle detection device 26 also outputs a magnetic angle signal 35, as shown in Figure 3. This magnetic angle signal 35 is generated in a magnetic sensor element 37 based on a radially magnetized magnet 36, which is located on the side of an output gear 25 facing the circuit board 19 and rotated by the output gear 25 above the magnetic sensor element 37.
[0051] From the track signals 33, 34 and the magnetic angle signal 35, the overall rotation angle 22 of the steering shafts 7 and 11 is calculated on the circuit board 19 and output via the output interface 38. This calculation will be described in detail below with reference to Figures 3 to 7.
[0052] First, the individual signals 33-35 are converted into sawtooth signals in corresponding conversion units, such that there are sawtooth signals 39 for coarse tracks, sawtooth signals 40 for fine tracks, and magnetic sawtooth signals 41. Next, the sawtooth signal 39 of the coarse track and the sawtooth signal 40 of the fine track are combined in a synthesis unit based on a suitable vernier algorithm to form an intermediate angle signal 42.
[0053] This combination will be explained in more detail with reference to Figures 4 and 5. In these figures, the signal values 43 of each signal are qualitatively plotted over the rotation angle 22 to be measured. In this case, the sawtooth signals 39 and 40 are generated such that their respective signal values 43 increase directly in proportion to the rotation angle 22 with a proportionality constant of 1.
[0054] Based on the fine track count of the 12 fine track blades and the coarse track count of the 8 coarse track blades described above, the sawtooth signal 40 of the fine track has a fine track period length 44 of 30°, while the sawtooth signal 39 of the coarse track has a coarse track period length 45°. Since the least common multiple of these two period lengths is 90°, the intermediate angle signal 42 can be measured from these two sawtooth track signals 39 and 40 over an intermediate angle period length 46 of 90°.
[0055] The Bezoux coefficients of the corresponding linear combination 50 of the fine-track sawtooth signal 40 and the coarse-track sawtooth signal 39 for forming the intermediate angle signal 42 are 3 for the fine-track sawtooth signal 40 and 2 for the coarse-track sawtooth signal 39, so the intermediate angle signal 42 can be constructed from this linear combination. If necessary, the linear combination must be offset by the intermediate angle period length 46 if the intermediate angle signal 42 is 0 or less. The intermediate angle signal 42 obtained in this way is shown in Figure 4.
[0056] However, the intermediate angle signal 42 can become distorted, especially when torque is applied to the entire control shaft 7, 11. This can lead to measurement errors. To avoid these measurement errors, modulo division 47 is applied to the intermediate angle signal 42, with the divisor being the fine track sawtooth signal 40. Next, the quotient 48 of this modulo division 47 is multiplied by the fine track sawtooth signal 40, and the remainder of the modulo division 47 is discarded.
[0057] In this way, if the sawtooth signal 39 of the coarse track is shifted relative to the sawtooth signal 40 of the fine track, and the intermediate angle signal 42 is affected by the error, this error is filtered out by the method described above.
[0058] In this context, it should be noted that the tracks 17 and 18 of the sawtooth signals 39 and 40, used as a reference for determining the corresponding corrected intermediate angle signal 49, should be positioned on the side opposite the steering handle 6 in order to detect the steering angle 13 without error. While the sawtooth signal 39 with a coarse track can, in principle, also be used in the correction method described above, the sawtooth signal 40 with a fine track inherently has higher resolution and is therefore more suitable for correction. While the sawtooth signals 39 of coarse tracks can, in principle, be used in the correction method described above, the sawtooth signals 40 of fine tracks are inherently more suitable for correction because they have higher resolution.
[0059] Finally, the final determined rotation angle 22 is calculated by a further linear combination 50 of the corrected intermediate angle signal 49 and the magnetic sawtooth signal 41. If all the aforementioned sawtooth signals are generated such that the signal value 43 changes in direct proportion to the rotation angle 22 with a proportionality constant of 1, the rotation angle 22 can be read directly from the result of the second linear combination, as shown in Figure 7. Here, the rotation angle 22 is reliably detected within an angular range 51 of ±855°.
Claims
1. A sensor (9) for detecting the rotation angle (22) of a shaft (7,11) and a torque angle (16) that depends on the torque acting on the shaft (7,11), wherein the shaft (7,11) is divided into a first shaft portion (11), a second shaft portion (7), and a torsion element separating the first shaft portion (11) and the second shaft portion (7), A rough track (18) is arranged circumferentially around the first shaft portion (11), and is denoted by the symbol A, and is arranged at equal distances from each other, having a large number of rough track elements (29). A fine track (17) is arranged circumferentially around the second shaft (7), and is denoted by the symbol B, and is arranged at equal distances from each other, having a large number of fine track elements (27) that are greater than the number of coarse track elements. The system includes a detection unit (19) configured to detect rotation angle and torque angle within a maximum torque angle range indicated by symbol T and a maximum rotation angle range indicated by symbol S, based on the angular position (34) of the coarse track (18) and the angular position (33) of the fine track (17). In a sensor where the ratio of the number of coarse track elements to the number of fine track elements is not an integer, The number of coarse track elements and the number of fine track elements are as follows: [Number 9] Satisfying the requirements, Here, the function gcd(A,B) represents the determination of the greatest common divisor, and the symbol Θ represents the measurement of a full-angle angle, characterized in that this is a sensor.
2. The sensor (9) according to claim 1, wherein the number of coarse track elements and the number of fine track elements have a common common denominator.
3. The coarse track (18) and the fine track (17) are configured to modify the electrical and / or magnetic properties of space as a function of the angular positions (34, 33) of the tracks (17, 18), and a detection unit (19) for detecting the angular positions (34, 33) of the coarse track (18) or the fine track (17) is configured to generate an electrical coarse track signal (39) or a fine track signal (40), respectively, which depends on the electrical and / or magnetic properties of space, the sensor (9) according to claim 1 or 2.
4. The detection unit (19) is configured to detect a coarse track signal (39) having an electrical coarse track signal error indicated by the symbol EA, and a fine track signal (40) having an electrical fine track signal error indicated by the symbol EB, where the number of coarse track elements and the number of fine track elements are determined by the torque angle error (16) denoted by the symbol ET. [Number 10] The sensor (9) according to claim 3, selected to satisfy the following conditions, where the symbol C can be selected as any real value.
5. The aforementioned maximum rotation angle range (51) is, [Math 11] Preferably [Math 12] A sensor (9) according to any one of claims 1 to 4, selected to satisfy the following conditions.
6. The aforementioned maximum torque angle range is subject to the conditions [Number 13] A sensor (9) according to any one of claims 1 to 5, selected to satisfy the following conditions.
7. The number of coarse track elements and the number of fine track elements are 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 sensor (9) according to any one of claims 1 to 6, selected from A=18 and B=12.
8. A method for detecting the rotation angle (22) of a shaft (7, 11) using a sensor (9) according to any one of claims 1 to 7, A process for detecting the angular position (34) of the rough track (18), A process for detecting the angular position (33) of the fine track (17), A step of determining the length of multiple periods (44) over which the angular position (33) of the fine track (17) has already passed, based on the angular position (18) of the detected coarse track, A method comprising the step of correcting the angular position (33) of a fine track (17) based on the number of determined period lengths (44) of the angular position (33) of the fine track (17).
9. The method according to claim 8, wherein the angular position (33) of the fine track (17) is added to the number of determined period lengths (44) in order to correct the angular position (33) of the fine track (17).
10. A control device (19) for carrying out the method described in claim 8 or 9.