Method for determining a translation path or a position of a push rod in a steering system of a vehicle

Abstract

Method for determining a push rod position and / or a translation path of a push rod (1) in a steering system of a vehicle, comprising - generating a translational movement (S1) of the push rod (1) and a rotational movement of the rotatable element (3) by a rotation angle, - determining a first angle of rotation measured value (S2) with the first angle sensor (6), based on a received value of the first output signal, - determining a second angle of rotation measured value (S3) with the second angle sensor (10) based on a received value of the second output signal, - determining, in particular calculating, the numerical value of the angle of rotation (S4) of the rotatable element (3) from the first angle of rotation measurement value and the second angle of rotation measurement value, - Determining the numerical value (S5) of the translation path or the position of the push rod (1) from the numerical value of the angle of rotation.

Description

[0001] The invention relates to a method for determining a translation path or the position of a push rod in a steering system of a vehicle and a steering system of a vehicle which allows the determination of the translation path or the position of a push rod.

[0002] Determining the pushrod position in a steer-by-wire steering system requires absolute position measurement (true power-on). Position determination must be significantly more precise than in conventional steering systems with a mechanical coupling to the steering wheel. This places special demands on the accuracy of the sensors and safety, and thus also represents a cost factor.

[0003] If the entire travel of the rack is to be measured with a single sensor element, it must either be very large or enable a very high angular resolution. With current measurement technology, the angular accuracy cannot be measured with sufficient precision, is not absolute, or only at great expense. For example, measuring the rack position directly at the rack using a linear measurement method would be very costly.

[0004] EP 2 180 296 A1 discloses a rotation angle determination device for determining the rotation angle position of a rotating shaft, comprising: a main rotor coupled to the rotating shaft, on which a first sensor unit is arranged for determining the rotation angle position of the main rotor; an auxiliary rotor rotationally coupled to the main rotor, on which a second sensor unit is arranged for determining the rotation angle position of the auxiliary rotor; wherein the sensor units comprise at least one inductively acting sensor and at least one magnetically acting sensor. This solution is mechanically / structurally complex.

[0005] The following position detection devices are also known from the state of the art:

[0006] DE 10 2019 207 070 A1 discloses a rotor position sensor for determining the angular position of a rotor shaft of an electric motor, comprising a sensor element which can be fastened to the end of the rotor shaft and which has at least one centrally arranged sensor magnet, and comprising at least one magnetic field sensor which can be positioned opposite the sensor magnet on a circuit carrier in the extension of the motor shaft and which is designed to output a first sensor signal which is dependent on the angular position of the sensor element, wherein at least one electrically conductive region which is delimited in a circumferential direction surrounding the sensor magnet is provided on the sensor element for inductive interaction with a coil system arranged on the circuit carrier for generating a second sensor signal which is dependent on the angular position of the sensor element, as well as a steering system for a motor vehicle comprising the rotor position sensor according to the invention.

[0007] FR 3 123 118 A1 relates to a position detection device for installation in a vehicle with a drive shaft extending along a longitudinal axis of rotation and at the end of which a target is mounted, the target comprising a gear and a magnet fixed in the center of the gear, the device comprising: - a housing provided with a bottom wall, - a printed circuit comprising a surface fixed to the bottom wall and an upper side on which the following are mounted: an inductive sensor comprising at least one coil arranged in a circle around a center point, a magnetic sensor whose center point coincides with the center point of the inductive sensor, the upper side of the printed circuit being intended to be mounted to the right of the target.

[0008] The object of the present invention is to provide a method for accurately determining a translational path or the position of a push rod in a vehicle steering system, wherein the method should be feasible with the lowest possible construction and cost. Furthermore, the invention should provide a steering system designed for this purpose.

[0009] This object is achieved by a method for determining a translational path or the position of a push rod in a steering system of a vehicle and a steering system of a vehicle according to the independent claims. Specific embodiments of the invention are specified in the subclaims and in this description.

[0010] The invention relates to a method for determining a push rod position and / or a translation path of a push rod in a steering system of a vehicle, wherein the push rod is coupled to a rotatable element in such a way that a translational movement of the push rod is accompanied by a rotational movement of the rotatable element and a numerical value of a translational path can be assigned to a numerical value of a rotational angle of the rotatable element, wherein the rotatable element is rotatable about a rotation axis and has a first sensor element of a first angle sensor and a second sensor element of a second angle sensor, wherein the first sensor element and the second sensor element are connected to the rotatable element in a rotationally fixed manner and each have at least two planes of symmetry, the intersection line of which is congruent or aligned with the rotation axis, wherein, upon rotation of the rotatable element about the axis of rotation, the first angle sensor generates a rotation angle-dependent first output signal, and the second angle sensor generates a rotation angle-dependent second output signal, wherein the first output signal is repeated periodically x times during a rotational movement of the rotating element by 360°, where x is a fixed value of x ≥ 0, wherein the second output signal is repeated periodically y times during a rotational movement of the rotatable element by 360°, where y is a fixed value of y > 0, and y > x, the method comprising: - Generating a translational movement of the push rod and a rotational movement of the rotating element by a rotation angle, - Determining a first rotation angle measurement value with the first angle sensor, based on a received value of the first output signal, and preferably further based on the value of x, - Determining a second rotation angle measurement value with the second angle sensor on the basis of a received value of the second output signal, and preferably further on the basis of the value of y, - Determining, in particular calculating, the numerical value of the angle of rotation of the rotating element from the first angle of rotation measurement value and the second angle of rotation measurement value, - Determining the numerical value of the translation path and / or the position of the push rod (push rod position) from the numerical value of the angle of rotation.

[0011] The specified sensor combination enables high-precision angle detection and high-precision position determination of the push rod on a single axis, without the need for a mechanical reduction stage for a second angle sensor. The solution is cost-effective, robust against dust and dirt, and electromagnetically compatible.

[0012] The invention allows for spatial separation between the encoder elements of the angle sensors and the receiver elements. This spatial separation allows a rotary encoder to become wet without significantly degrading the signal quality.

[0013] According to the invention, both angle sensors are advantageously arranged on the same axis of rotation, which represents a significant structural simplification.

[0014] The steering system is preferably a steer-by-wire system.

[0015] The method can be used to determine a translational path of the push rod and / or the push rod position. The push rod position can be determined from the translational path and a reference position (assumed to be known), which can be, for example, a zero position or an end position.

[0016] A zero position is preferably a position of ideal straight-ahead travel. A zero position can be determined relative to a reference object, for example, a steering housing. The zero position can be defined as a coordinate relative to the reference object, for example, the steering housing.

[0017] In one embodiment of the invention, the push rod may be a rack.

[0018] In the steering system, a translational movement of the push rod can preferably be converted into a pivoting movement of movable wheels, wherein the wheels are coupled to the push rod, for example via tie rods.

[0019] The fact that a translational movement of the push rod is accompanied by a rotational movement of the rotating element says nothing about whether the push rod is a driving or driven element. The rotating element can be part of an actuator that acts on the push rod to move it translationally. For example, the actuator can be a ball screw drive (KGT). In another variant, the rotating element can be driven by the push rod to serve purely as a measuring device. In other embodiments, the rotating element can be a steering pinion or another rotating element of a steer-by-wire steering system.

[0020] The push rod can be mechanically and / or electrically coupled to a rotating element.

[0021] The rotatable element preferably has one or more end faces. The first angle sensor and the second angle sensor can be mounted on different end faces or on the same end face, which is preferred because it allows for a space-saving and simple design. The axis of rotation runs through the end face, preferably centrally. Mounting on an end face of a rotatable element, especially if this is a shaft, is also referred to as end-of-shaft positioning.

[0022] The first angle sensor preferably has the first sensor element and a further sensor element. The first sensor element of the first angle sensor can be a transmitter element or a receiver element. If the first sensor element of the first angle sensor is a transmitter element, which is preferred, an associated receiver element is provided as the further sensor element. If the first sensor element of the first angle sensor is a receiver element, an associated transmitter element is provided as the further sensor element. Upon a rotational movement of the rotatable element about the rotation axis, the first sensor element rotates relative to the further sensor element.

[0023] The second angle sensor preferably has the second sensor element and a further sensor element. The second sensor element of the second angle sensor can be a transmitter element or a receiver element. If the second sensor element of the second angle sensor is a transmitter element, which is preferred, an associated receiver element is provided as the further sensor element. If the second sensor element of the second angle sensor is a receiver element, an associated transmitter element is provided as the further sensor element. Upon a rotational movement of the rotatable element about the rotation axis, the second sensor element rotates relative to the further sensor element.

[0024] The further sensor element of the first angle sensor and the second angle sensor can be structurally integrated, for example on a common circuit board.

[0025] The first and second output signals are preferably electrical signals. The first and second output signals each represent at least one signal. For example, one or more additional first and / or second output signals may be present, which may depend on the sensor type.

[0026] The first angle sensor can be selected from a Hall sensor, a TMR sensor, a GMR sensor, an AMR sensor, or an inductive sensor.

[0027] The second angle sensor can be selected from a Hall sensor, a TMR sensor, a GMR sensor, an AMR sensor, or an inductive sensor, with an inductive sensor being preferred.

[0028] The first and second angle sensors can be calibrated using one or more reference sensors. Such calibration is preferably performed specifically for an individual vehicle. A reference sensor is preferably a highly accurate or calibrated sensor that preferably measures relative to a reference position already mentioned above. Calibration data of the first and / or second angle sensors are preferably stored in software, for example, in an electronic control unit (ECU).

[0029] In one embodiment of the method, x = 0, so that the first output signal does not repeat periodically at a rotation angle of 360°. In this embodiment, the first angle sensor can map up to one complete revolution of the rotating element without having to consider the period in which the first output signal was obtained.

[0030] In a further embodiment of the method, x = 1.

[0031] In one embodiment of the invention, x and y are integers.

[0032] In one embodiment of the method, y ≥ 8, so that the second output signal repeats periodically at least 8 times for a rotation angle of 360°, correspondingly the number of periods = y + 1 = 9. Even more preferably, y ≥ 10, y ≥ 11, y ≥ 13, y ≥ 15, y ≥ 17, y ≥ 19, y ≥ 21, y ≥ 23, y ≥ 25, y ≥ 27, or y ≥ 29, so that the second output signal repeats periodically by the corresponding specified number. In this embodiment, increasingly higher accuracies of the second angle sensor can be achieved with an increasingly reduced measuring range.

[0033] In one embodiment of the method, the second angle sensor has a smaller angle measuring range than the first angle sensor, wherein the measuring range of the first angle sensor is 360° / (x+1) and the measuring range of the second angle sensor is 360° / (y+1). It applies that y > x. Example: The measuring range of the first angle sensor 360° / (x+1) is, for example, 360° / (1+1) = 180° for a single periodic repetition (x = 1). The measuring range of the second angle sensor 360° / (y+1) is, for example, 360° / (9+1) = 36° for a nine-fold periodic repetition (y = 9). The ratios 1:(x+1) and 1:(y+1) are each also referred to as the transmission ratio of mechanical to electrical revolution, or as the electrical transmission ratio. In this embodiment, the second angle sensor covers a smaller measuring range with preferably higher resolution, which allows more accurate results to be achieved.

[0034] In one embodiment of the method, the second angle sensor has a lower percentage or absolute measurement error than the first angle sensor.

[0035] Due to the higher accuracy of the second angle sensor, preferably in conjunction with a smaller measuring range, as stated in the previous embodiment, a higher accuracy of the angle determination can be achieved.

[0036] In one embodiment of the method, in a period of the first output signal, each value of the first output signal is assigned an angle value (also referred to as electrical angle value) in the range of β = 0 - 360° and the first rotation angle measurement value is determined according to the following relationship: first angle measurement value = β / (x+1).

[0037] In one embodiment of the method, in a period of the second output signal, each value of the second output signal is assigned an angle value (also referred to as electrical angle value) in the range of γ = 0 - 360° and the second rotation angle measurement value is determined according to the following relationship: second angle measurement value = γ / (y+1).

[0038] In the previous embodiment, the ratios 1:(x+1) and 1:(y+1), each also referred to as the transmission ratio of mechanical to electrical revolution, are used to easily obtain the first and second rotation angle measurement values, respectively. As already stated in previous embodiments, it is advantageous to use a relatively low value for x, preferably 0 or 1, and a comparatively high value for y (exemplary embodiments given above).

[0039] The determination, in particular the calculation, of the numerical value of the rotation angle of the rotating element from the first rotation angle measurement value and the second rotation angle measurement value can be performed using a Vernier algorithm, also known as a Vernier algorithm. Methods for evaluation using the Vernier method are disclosed, for example, in Matteo Dalboni and Alessandro Soldati, "Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method," IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 72, 2023.

[0040] In one embodiment of the method, the numerical value of the angle of rotation of the rotatable element is determined from the first angle of rotation measurement value and the second angle of rotation measurement value as follows: The first angle measurement is used to determine the numerical value of the angle of rotation of the rotating element as a rough value, and this rough value is refined using the second angle measurement as a fine value to obtain the numerical value of the angle of rotation of the rotating element. It is particularly advantageous to evaluate the first angle measurement and the second angle measurement, or the first and second output signals, using a Vernier algorithm, also known as a Vernier algorithm.

[0041] In one embodiment, which can be particularly advantageously combined with previous embodiments, a uniquely assigned numerical value of the angle of rotation can be assigned to a value pair consisting of the first and second angle of rotation measured values, or a value pair consisting of the first output signal and the second output signal, or can be determined from the value pair. In this embodiment, the numerical value of the angle of rotation, also referred to as the total angle, is determined from the combination of the first and second angle of rotation measured values, or from the combination of the first output signal and the second output signal.

[0042] In its installed position, the push rod has a total stroke, also referred to as the maximum stroke. Preferably, a pair of values for a combination of the first and second angle measurement values, or a pair of values for a combination of the first output signal and the second output signal, repeats during the movement of the push rod only after its total stroke has been covered. In other words, each of the aforementioned pairs of values occurs only once during the total stroke.

[0043] In one embodiment of the method, the second sensor element (of the second angle sensor) is arranged concentrically around the first sensor element (of the first angle sensor). The first sensor element can be, for example, a magnet of a Hall sensor arranged on the rotation axis and pierced by the rotation axis. The second sensor element can be, for example, a sensor coil of an inductive sensor surrounding the rotation axis. In another embodiment, the arrangement can be reversed, so that the first sensor element is arranged concentrically around the second sensor element.

[0044] In a further aspect, the invention relates to a steering system of a vehicle, comprising a push rod which is coupled to a rotatable element in such a way that a translational movement of the push rod is accompanied by a rotational movement of the rotatable element and a numerical value of a translational path can be assigned to a numerical value of a rotational angle of the rotatable element, wherein the rotatable element is rotatable about a rotation axis and has a first sensor element of a first angle sensor and a second sensor element of a second angle sensor, wherein the first sensor element and the second sensor element are connected to the rotatable element in a rotationally fixed manner and each have at least two planes of symmetry whose intersection line is congruent or aligned with the rotation axis, wherein, upon rotation of the rotatable element about the axis of rotation, the first angle sensor generates a rotation angle-dependent first output signal, the second angle sensor generates a rotation angle-dependent second output signal, wherein the first output signal is repeated periodically x times during a rotational movement of the rotating element by 360°, where x is a fixed value of x ≥ 0, wherein the second output signal is repeated periodically y times during a rotational movement of the rotatable element by 360°, where y is a fixed value of y > 0 and y > x, The steering system further comprises: - a device for determining a translation path of the push rod, which is designed to - in generating a translational movement of the push rod and a rotational movement of the rotatable element by a rotation angle - to obtain a first angle of rotation measured value of the first angle sensor, wherein the first angle of rotation measured value can be determined on the basis of a received value of the first output signal, - to obtain a second angle of rotation measured value of the second angle sensor, wherein the second angle of rotation measured value can be determined on the basis of a received value of the second output signal, - to determine the numerical value of the angle of rotation of the rotating element from the first angle of rotation measurement value and the second angle of rotation measurement value, - to determine a translational path of the push rod from the numerical value of the angle of rotation.

[0045] The steering system according to the invention can be configured for any method according to the invention described above. Structural features described in previous methods can also be features of the steering system according to the invention. Conversely, the method according to the invention can utilize any structural element of a steering system according to the invention.

[0046] In one embodiment, the method according to the invention further comprises: The comparison between the determined position of the push rod and a push rod position calculated by an engine position sensor.

[0047] Furthermore, the method according to the invention can comprise: Detection of a belt jump in the event of a deviation of the determined position of the push rod from the push rod position calculated by an engine position sensor.

[0048] The belt is part of the steering system. The belt is preferably a power transmission means in the steering system between a motor, which has the motor position sensor, and the wheels.

[0049] According to this further inventive idea, a comparison of this sensor information with an engine position sensor can be used to detect a belt jump. There is an engine position sensor that detects an angle on the steering system motor. According to this further inventive idea, a comparison is made between the push rod position determined using the inventive method and a push rod position calculated by the engine position sensor. If these positions differ from one another while driving or after a restart, a belt jump (belt jumps over the belt pulleys in high-load situations (e.g. workshop test)) can be concluded or detected. If a belt jump occurs too frequently, this indicates a fault in the steering system (e.g. moisture in the belt compartment, belt is damaged, axle distances are too small, etc.).

[0050] If a belt jump is detected, the driver can be notified of an error.

[0051] The invention is described below using exemplary embodiments. They show: Fig. 1 shows a structure according to the invention for carrying out a method according to the invention; Fig. 2 a plan view of a structure according to Fig. 1; Fig. 3 a structure of a second angle sensor; Fig. 4 shows a relationship between the rack position and the electrical angle values of the first angle sensor and the second angle sensor; Fig. 5 a first sensor element of a first sensor according to a further embodiment; Fig. 6 shows a relationship between the rack position and the rotation angle measured values of the first angle sensor and the second angle sensor according to a further embodiment; Fig. 7 shows an example procedure.

[0052] in Fig. 1 shows a rack 1, a special embodiment of a connecting rod. The rack 1 is coupled to the rotating element 3 via the mechanical coupling element 2 in a manner shown only schematically. A coupling element 2 is not mandatory. The rotating element 3 could also be a pinion whose teeth engage directly with the rack 1. Furthermore, the rotating element 3 and the rack 1 are not shown to scale.

[0053] The rack 1 is coupled to the rotatable element (3) in such a way that a translational movement of the rack 1 is accompanied by a rotational movement of the rotatable element 3 and a numerical value of a rotational angle of the rotatable element 3 can be assigned a numerical value of a translational path of the rack 1 in the direction X1 or X2.

[0054] The rotating element 3 is rotatable about the rotation axis D. The rotating element 3 is, for example, a round disc in side view, through whose center the rotation axis D runs.

[0055] A first sensor element 5 of the first angle sensor 6 is mounted on the end face 4 of the rotating element 3. In this case, the first sensor element 5 is embedded in the rotating element 3 on the end face 4. The first angle sensor has the additional sensor element 7. The first angle sensor 6 is a Hall sensor, with the first sensor element 5 being a two-pole magnet that serves as a sensor magnet, and the additional sensor element 7 being an integrated circuit in which a first output signal 13 (coarse track ASIL-D) is generated, which determines the absolute rack position. The additional sensor element 7 is mounted on a stationary circuit board 8.

[0056] On the front side 4 of the rotating element 3, a second sensor element 9 of the second angle sensor 10 is also mounted. This is a metal toothed ring, which corresponds to the following Fig. 2. The additional sensor element 11 of the second angle sensor 10 is also mounted on the circuit board 8. The additional sensor element 11 is a wire coil. In this example, the second angle sensor 10 is an inductive sensor, for example a CIPOS® sensor, which, via the evaluation unit 19, delivers a periodic output signal (fine track, ASIL-D) as a second output signal 14, which is used to determine the relative rack position.

[0057] Fig. Figure 2 shows a top view of the rotating element 3, the first sensor element 5, and the second sensor element 9. Two exemplary planes of symmetry E1 and E2 are shown, which are perpendicular to the drawing plane and form the intersection line SG, which is also perpendicular to the drawing plane. The intersection line SG is congruent with the rotation axis D.

[0058] Fig. Figure 3 shows an embodiment of a second angle sensor 10, which is a CIPOS® sensor. The second sensor element 9 is a metal ring with 18 teeth. This results in an electrical ratio of 18 to 1. The sensor provides a periodic output signal that repeats every 360° / 18 = 20° upon rotation of the second sensor element 9 relative to the further sensor element 11, which is a coil. The second sensor element 9 is a Fig. 3 a metal ring with 6 teeth, with an electrical ratio of 6 to 1 and a period that repeats every 60°.

[0059] The structure of the sensor in Fig. 2 shows only the 2nd angle sensor, not the one in Fig. 1 shown first angle sensor. It should be connected to the Fig. 2 only illustrates the structure of the elements of the second angle sensor. Therefore, the circuit board is designated as 8', because it differs from the circuit board 8 in Fig. 1 at least in that there is a hole in the middle and no integrated circuit as a further sensor element 7 of the first angle sensor.

[0060] Fig. Figure 4 shows, in one exemplary embodiment, a relationship between the position of the rack 1 and the rotation angle measurements of the first angle sensor 6 with the first output signal 13 (coarse track) and of the second angle sensor 10 with the second output signal 14 (fine track). The rotatable element 3 rotates 360° with a rack stroke of 210 mm.

[0061] The output signals (sensor signals) 13 of the coarse track are provided redundantly with a high level of availability and accuracy (ASIL-D). The first angle sensor 6 in the center, on the rotation axis, is an ASIL-D-compatible sensor with a digital output, e.g., an "Allegro A33022" (Hall-based) Sent output signal. Alternatively, a sensor with 2x ASIL-B(D) and Fusion within the electronic control unit (ECU) can be used (e.g., TDK HAR 3930). This sensor has realistic angular accuracy according to all tolerances: approximately +-0.8° according to the data sheet. This results in a measurement error in the rack position of +-0.47 mm with ASIL-D when translating rack 1. This first angle sensor 6 serves to comply with the FUSI limit. The first angle sensor 6 in the center is used as the coarse track.

[0062] The outer track is designed with the second angle sensor 10 as an inductive sensor. This has a ratio of 30:1. This means: For an angle change of 360 degrees at the sensor encoder, the electrical output signal 14 of the inductive sensor repeats 30 times (Note: in Fig. 3, the second angle sensor has an electrical ratio of 18:1. The second angle sensor 10 is used as a fine track. The fine track signals can be provided with a lower availability (ASIL-B).

[0063] The calculation of the absolute position of rack 1 is as follows: Based on the coarse track with the first angle sensor 6 (with a larger angle error) it can be determined roughly where the rack 1 is located.

[0064] Using the fine track with the second angle sensor 6, the rack position P can be determined more precisely (an output signal accuracy of +-2° is expected, corresponding to a rack position accuracy of +-0.039 mm). The 2° refers to the electrical accuracy of the fine track. For example, with an electrical ratio of 1:30, this means a mechanical accuracy of 0.067 degrees. This signal can be provided redundantly with high quality (up to ASIL-D) or simply as a functional signal (no ASIL, no redundancy, more cost-effective).

[0065] β denotes the electrical angle value of the first output signal of the first angle sensor 6.

[0066] γ denotes the electrical angle value of the second output signal of the second angle sensor 10.

[0067] The evaluation and combination of both sensor information, from the first angle sensor 6 and the second angle sensor 10, into an absolute angle, the numerical value of the angle of rotation of the rotating element 3, takes place directly on the ECU. In this example, the evaluation is performed as follows: The coarse track angle available with ASIL-D indicates which electrical revolution the outer sensor (fine track) is on. For example, the coarse track indicates the rack position P of x +- 0.039 mm in the range from 0 to 210 mm. Now you can look at the fine track, which does not cover the entire rack stroke (e.g. the signal repeats every 7 mm (corresponds to 30 electrical revolutions for one mechanical revolution). However, the accuracy for this limited range is significantly more precise. This allows a precise rack position P to be obtained from the combination of both sensors. The coarse track is used to determine which revolution of the fine track you are on. The fine track provides the high level of accuracy.

[0068] Another embodiment according to Fig. 5 and Fig. 6 illustrate the application of the Vernier principle: The first sensor element 12 of the first angle sensor is in Fig. 5 a magnet with four magnetic poles 15, 16, 17, 18. Thus, one mechanical revolution results in two electrical revolutions of the sensor signal (x = 1, x +1 = 2).

[0069] If the inductive sensor has an unequal multiple of electrical revolutions, an overall position can be determined from the combination of the two.

[0070] Fig. Figure 6 shows the simplest case for illustration. The reference symbols have the same meaning as in previous figures, for example as in Fig. 4. The first angle sensor 6 (Hall sensor) makes two electrical revolutions per complete mechanical revolution of the rotating element. The second angle sensor 10 (inductive sensor) makes three electrical revolutions per complete mechanical revolution of the rotating element.

[0071] Because each electrical angle combination (including tolerances) of the first angle sensor and the second angle sensor is unique over a 360° rotation, only one mechanical angle position can be the correct one by combining both angles. Example:

[0072] The mechanical angle (numerical value of the angle of rotation of the rotating element) is 180°. The electrical angle of the first sensor (2-fold translation, coarse track) is 360°, which looks like 0° to the sensor.

[0073] The electrical angle of the second sensor (29 gear ratio, fine track) is 29*180°= 5220°, which looks like 180° to the sensor.

[0074] This combination only occurs once. Therefore, it can be concluded that you are not at the mechanical 0° position, but at the mechanical 180° position.

[0075] For further information on the evaluation method, please refer to the publication: Matteo Dalboni and Alessandro Soldati, Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method, IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 72, 2023.

[0076] Fig. Figure 7 shows a method sequence according to the invention. The method relies on previously described features and the following: S1: Generating a translational movement of the push rod 1 and a rotational movement of the rotatable element 3 by a rotation angle. The rotatable element 3 can be an actuator and drive the push rod 1 or can be driven by the push rod 1, for example, if the push rod 1 is driven by another actuator. S2: Determining a first angle measurement value with the first angle sensor 6, based on a received value of the first output signal. The first angle sensor 6 provides the first output signal, from which a rotation angle is determined, which is the first angle measurement value. S3: Determining a second angle measurement value with the second angle sensor 10 based on a received value of the second output signal. The first angle sensor 10 provides the second output signal, from which a rotation angle is determined, which is the second angle measurement value. S4: Determining, in particular calculating, the numerical value of the rotation angle of the rotatable element 3 from the first rotation angle measurement value and the second rotation angle measurement value. For this purpose, a Vernier algorithm, for example, is used. S5: Determine the numerical value (S5) of the translation path or the position of the push rod (1) from the numerical value of the angle of rotation.

[0077] S1 to S5 do not necessarily have to occur in this order if technically possible. Other sequences or simultaneous processes are possible. This applies in particular to S3 and S4. List of reference symbols 1 push rod / rack 2 coupling element 3 rotating element 4 Front side 5 first sensor element of the first angle sensor 6 first angle sensor 7 additional sensor element of the first angle sensor 8 circuit board 8' circuit board 9 second sensor element of the second angle sensor 10 second angle sensor 11 additional sensor element of the second angle sensor 12 first sensor element of the first angle sensor 13 first output signal 14 second output signal 15 magnetic pole 16 magnetic pole 17 Magnetic pole 18 magnetic pole 19 Evaluation unit D axis of rotation E1 plane of symmetry E2 plane of symmetry SG intersection line P Rack position X1 direction X2 direction β electrical angle value of the first output signal γ electrical angle value of the second output signal QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 180 296 A1

[0004] DE 10 2019 207 070 A1

[0006] FR 3 123 118 A1

[0007] Cited non-patent literature

[0000] Matteo Dalboni and Alessandro Soldati, Absolute Two-Tracked Optical Rotary Encoders Based on Vernier Method, IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 72, 2023 [0039, 0075]

Claims

[1] Method for determining a push rod position and / or a translation path of a push rod (1) in a steering system of a vehicle, wherein the push rod (1) is coupled to a rotatable element (3) in such a way that a translational movement of the push rod (1) is accompanied by a rotational movement of the rotatable element (3), and a numerical value of a translational path can be assigned to a numerical value of a rotational angle of the rotatable element (3), wherein the rotatable element is rotatable about a rotational axis (D) and has a first sensor element (5) of a first angle sensor (6) and a second sensor element (9) of a second angle sensor (10), wherein the first sensor element (5) and the second sensor element (9) are connected to the rotatable element (3) in a rotationally fixed manner and each have at least two planes of symmetry (E1, E2) whose intersection line (SG) is congruent or aligned with the rotational axis (D), wherein, upon rotation of the rotatable element (3) about the rotation axis (D), the first angle sensor (6) generates a rotation angle-dependent first output signal (13), and the second angle sensor (10) generates a rotation angle-dependent second output signal (14), wherein the first output signal is repeated periodically x times during a rotational movement of the rotatable element (3) by 360°, where x is a fixed value of x ≥ 0, wherein the second output signal is repeated periodically y times during a rotational movement of the rotatable element (3) by 360°, where y is a fixed value of y > 0, and y > x, the method comprising: - generating a translational movement (S1) of the push rod (1) and a rotational movement of the rotatable element (3) by a rotation angle, - determining a first angle of rotation measured value (S2) with the first angle sensor (6), based on a received value of the first output signal (13), - determining a second angle of rotation measured value (S3) with the second angle sensor (10) on the basis of a received value of the second output signal (14), - determining, in particular calculating, the numerical value of the angle of rotation (S4) of the rotatable element (3) from the first angle of rotation measurement value and the second angle of rotation measurement value, - Determine the numerical value (S5) of the push rod position and / or the translation path from the numerical value of the angle of rotation. [2] Method according to claim 1, wherein x = 0, so that the first output signal (13) does not repeat periodically at a rotation angle of 360°, [3] Method according to claim 1 or 2, wherein y ≥ 8, so that the second output signal (14) repeats periodically at least 8 times at a rotation angle of 360°, [4] Method according to one of the preceding claims, wherein the second angle sensor (10) has a smaller angle measuring range than the first angle sensor (6), wherein the measuring range of the first angle sensor (6) is 360° / (x+1) and the measuring range of the second angle sensor (10) is 360° / (y+1). [5] Method according to one of the preceding claims, wherein the second angle sensor (10) has a lower percentage or absolute measurement error than the first angle sensor (6). [6] Method according to one of the preceding claims, wherein in a period of the first output signal, each value of the first output signal (13) is assigned an angle value in the range of β = 0 - 360° and the first rotation angle measurement value is determined according to the following relationship: first angle measurement value = β / (x+1). [7] Method according to one of the preceding claims, wherein in a period of the second output signal, each value of the second output signal (14) is assigned an angle value in the range of y = 0 - 360° and the second rotation angle measurement value is determined according to the following relationship: second angle measurement value = γ / (y+1). [8] Method according to one of the preceding claims, wherein the numerical value of the angle of rotation of the rotatable element (3) is determined as follows: from the first angle of rotation measurement value, the numerical value of the angle of rotation of the rotating element (3) is determined as a coarse value and this coarse value is made more precise by the second angle of rotation measurement value as a fine value in order to obtain the numerical value of the angle of rotation of the rotating element (3). [9] Method according to one of the preceding claims, wherein the second sensor element (9) is arranged concentrically around the first sensor element (5). [10] Steering system of a vehicle, comprising a push rod (1) coupled to a rotatable element (3) such that a translational movement of the push rod (1) is accompanied by a rotational movement of the rotatable element (3), and a numerical value of a translational path can be assigned to a numerical value of a rotational angle of the rotatable element (3), wherein the rotatable element (3) is rotatable about a rotational axis (D) and has a first sensor element (5) of a first angle sensor (6) and a second sensor element (9) of a second angle sensor (10), wherein the first sensor element (5) and the second sensor element (9) are connected to the rotatable element (3) in a rotationally fixed manner and each have at least two planes of symmetry (E1, E2) whose intersection line (SG) is congruent or aligned with the rotational axis (D), wherein, upon rotation of the rotatable element (3) about the axis of rotation (D), the first angle sensor (6) generates a rotation angle-dependent first output signal (13), the second angle sensor (10) generates a rotation angle-dependent second output signal (14), wherein the first output signal (13) is repeated x times periodically during a rotational movement of the rotatable element (3) by 360°, where x is a fixed value of x ≥ 0, wherein the second output signal (14) is repeated y times periodically during a rotational movement of the rotatable element (3) by 360°, where y is a fixed value of y > 0 and y > x, The steering system further comprises: - a device for determining a translation path of the push rod (1), which is designed to - in generating (S1) a translational movement of the push rod (1) and a -Rotational movement of the rotating element (3) by a rotation angle - to obtain a first rotation angle measurement value of the first angle sensor (6), wherein the first rotation angle measurement value can be determined on the basis of a received value of the first output signal (13), - to obtain a second rotation angle measurement value of the second angle sensor (10), wherein the second rotation angle measurement value can be determined on the basis of a received value of the second output signal (14), - to determine the numerical value of the angle of rotation of the rotating element (3) from the first angle of rotation measurement value and the second angle of rotation measurement value (S4), - to determine a translation path of the push rod (1) from the numerical value of the angle of rotation (S5).

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