Method for calibrating and / or initializing a steering sensor of a steering system - Patents.com

Abstract

The invention takes as its starting point a method for calibrating and / or initializing a steering sensor (10) of a steering system (12), in particular during operation of the steering system (12) in a vehicle (14), the steering system (12) comprising a steering wheel (16) and a torque sensor (18) assigned to said steering wheel (16), the steering sensor (10) being provided for capturing a displacement position of the steering wheel (16). It is proposed here to determine a torque characteristic quantity (20) by determining a torque in each case for a number of different displacement positions of the steering wheel (16) and to compare it with a reference characteristic quantity (22) for the calibration and / or initialization of the steering sensor (10).

Description

[Technical field]

[0001] The invention starts from a method for calibrating and / or initialising a steering sensor of a steering system according to the preamble of claim 1 and a vehicle according to the preamble of claim 9. The invention also relates to a control device with a computing unit for implementing such a method. [Background technology]

[0002] From the prior art, vehicles are known which comprise a conventional steering system, for example with a steering wheel in the form of a steering wheel, a wheel turning angle regulator in the form of a steering gear and a steering shaft for mechanically connecting the steering wheel to the wheel turning angle regulator. Also known are vehicles with steer-by-wire steering systems which make do without a direct mechanical connection between the steering wheel and the vehicle wheels to be steered and in which the steering settings at the steering wheel are transferred exclusively electrically. The latter comprise an operating unit which can be operated by the driver and at least one wheel turning angle regulator which is mechanically separated from the operating unit. Furthermore, steering systems of this kind in both cases comprise sensors, for example torque sensors and / or steering angle sensors, for controlling the operation of the steering system. Steering systems of this kind are known, for example, from DE 102008037870 A1 and DE 102018123615 A1.

[0003] Furthermore, the sensors used are safety-critical components that require particularly precise calibration and / or setting in order to avoid errors during driving operation. In this case, the corresponding calibration is usually performed manually during production or in the factory using special tools, such as leveling tools. However, simple recalibration and automation, which may be necessary, for example, due to aging and / or wear effects, cannot be achieved using the known calibration methods. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Patent No. 102008037870 [Patent Document 2] DE 102018123615 A1 Summary of the Invention [Problem to be solved by the invention]

[0005] Starting from these, the object of the present invention is to provide a method for calibrating and / or initializing a steering sensor and a vehicle having improved properties, in particular with regard to operational reliability and / or functional form. This object is achieved by the characterizing features of claims 1, 8 and 9, whereas preferred embodiments and developments of the invention can be read from the dependent claims. [Means for solving the problem]

[0006] Disclosure of the Invention The invention starts from a method, in particular a computer-implemented method, for calibrating and / or initializing a steering sensor of a steering system, in particular during operation of the steering system in a vehicle, in particular automatically and / or automatically, where the steering system comprises a steering wheel and a torque sensor assigned to the steering wheel. The torque sensor is provided in particular for capturing a torque acting on the steering wheel. The steering sensor is provided for capturing a displacement position of the steering wheel. "Provided" is to be understood in particular as meaning dedicatedly programmed, designed and / or equipped. An object being provided for a particular function is to be understood in particular as meaning that this object fulfills and / or performs this particular function in at least one application and / or operating state.

[0007] It is proposed here to determine a torque characteristic quantity, in particular by means of a torque sensor, for a number of different displacement positions of the steering wheel, in particular by determining a torque associated with the corresponding displacement position, and to compare it with a reference characteristic quantity, in particular for an automatic and / or automated calibration and / or initialization of the steering sensor. The torque characteristic quantity thus comprises a number of value pairs of the displacement position of the steering wheel and the associated torque. The reference characteristic quantity can be, for example, a further torque characteristic quantity equivalent to the torque characteristic quantity, which is determined, for example, by means of a redundant further torque sensor. However, preferably, a work set variable that is previously applied to the torque characteristic quantity is used as the reference characteristic quantity. In this case, the reference characteristic quantity can be determined, for example, in a calibrated reference system, in advance, for example, by means of test measurements, and can be stored in the operating memory of the vehicle. Particularly preferably, the torque characteristic quantity and the reference characteristic quantity are vectors. Based on this comparison, a difference and / or deviation between the torque characteristic quantity and the reference characteristic quantity is then determined and used for the calibration and / or initialization of the steering sensor. This embodiment can increase the operational reliability and / or improve the functional form. In particular, a particularly accurately calibrated and / or configured steering sensor can be provided, and greater versatility and better adaptation to changed operating conditions can be achieved.

[0008] Preferably, a torque is determined for at least four different displacement positions of the steering wheel, preferably at least 20 different displacement positions, particularly preferably at least 30 different displacement positions. Also preferably, the displacement positions are evenly distributed over the entire displacement range of the steering wheel. In this case, if the steering wheel is configured as a steering wheel, every displacement range is equivalent to one complete rotation of the steering wheel. This allows a particularly simple and / or accurate evaluation and calibration and / or initialization of the steering sensor to be achieved.

[0009] It is further proposed to use a Fourier transform, in particular a discrete Fourier transform (DFT) or preferably a fast Fourier transform (FFT), for the comparison of the torque characteristic quantity with the reference characteristic quantity. In so far as the torque characteristic quantity corresponds to a sinusoidal signal, the calibration and / or initialization of the steering sensor can be carried out here directly on the basis of the result of the Fourier transform. In this case, preferably on the basis of the actual and virtual ratios, in particular the angle ratios, of the result of the Fourier transform, the difference and / or deviation between the torque characteristic quantity and the reference characteristic quantity can be determined and used for the calibration and / or initialization of the steering sensor. This makes it possible, inter alia, to achieve particularly simple and / or resource-friendly evaluation algorithms.

[0010] Furthermore, it is proposed to use a cross-correlation for the comparison of the torque characteristic quantity with the reference characteristic quantity. In particular, in this case, a cross-correlation between the torque characteristic quantity and the reference characteristic quantity is calculated. In this connection, preferably, based on the maximum value of the cross-correlation, a difference and / or deviation between the torque characteristic quantity and the reference characteristic quantity is determined and used for the calibration and / or initialization of the steering sensor. An evaluation of this kind is particularly conceivable when the torque characteristic quantity deviates from a sinusoidal signal to a certain extent. As a result, inter alia, a particularly accurate evaluation can be achieved, whereby preferably a precisely calibrated and / or set steering sensor can be provided.

[0011] The steering wheel can be displaced, for example, manually and / or manually, in order to determine the torque characteristic quantity. However, it is preferably proposed that the steering system comprises at least one, in particular an electric and / or electronic, actuator unit in operative connection with the steering wheel, the steering wheel being displaced by a drive control of the actuator unit in order to determine the torque characteristic quantity. In particular, the steering wheel is in this case displaced automatically and / or automatically by a drive control of the actuator unit, whereby when the respective displacement position is reached, a corresponding torque is determined by means of a torque sensor, whereby a value corresponding to the torque is stored together with the corresponding displacement position as a value pair. The total of all value pairs thus determined from the displacement position of the steering wheel and the associated torque then forms the torque characteristic quantity. Furthermore, the steering system can in this case in particular be configured as a conventional steering system, in particular as an electric power steering, and can include a mechanical lead-in. In this case, the actuator unit can be configured as a steering actuator for assisting the manual moment applied to the steering wheel. However, preferably, the steering system is configured as a steer-by-wire steering system and in particular comprises an operating unit and at least one wheel turning angle regulator that is mechanically separated from the operating unit and is provided for varying the wheel turning angle of at least one wheel depending on the steering setting. In this case, the actuator unit is preferably part of the operating unit and is mechanically coupled to the steering wheel. Particularly preferably, the actuator unit is configured here as a feedback actuator for generating a steering resistance and / or a restoring moment at the steering wheel. The actuator unit is also preferably configured as an electric three-phase alternating current machine, in particular as a synchronous machine, particularly preferably as a permanently excited synchronous machine, and is preferably driven and controlled in at least one operating state using signals of a torque sensor and / or a steering sensor. As a result, a preferred automation can be achieved.

[0012] Furthermore, preferably, if the torque characteristic quantities are determined at times and / or in states where no contact connection with the steering wheel occurs and / or is not made, in particular in so-called hand-off states, the torque characteristic quantities can be determined accurately and independently of external influences.

[0013] Furthermore, the invention relates to a control device with a calculation unit for carrying out the above-mentioned method. A "calculation unit" is to be understood here in particular as meaning an electrical and / or electronic unit with an information input, an information processing and an information output. Advantageously, the calculation unit further comprises at least one processor, at least one operating memory, at least one input means and / or output means, at least one operating program, at least one open-loop control routine, at least one closed-loop control routine, at least one calculation routine, at least one calculation routine and / or at least one calibration routine. In particular, the calculation unit is provided for determining a torque characteristic quantity. In this case, the calculation unit is provided in particular for determining a torque for each of a number of different displacement positions of the steering wheel and generating a torque characteristic quantity therefrom. Furthermore, the calculation unit is provided in particular for comparing the torque characteristic quantity with a reference characteristic quantity for the calibration and / or initialization of the steering sensor. Furthermore, the calculation unit may be provided for driving an actuator unit, whereby the steering wheel is displaced automatically and / or automatically. The calculation unit is preferably integrated in a control device of the vehicle, which is here configured as a steering control device, as a result of which, inter alia, the advantages already mentioned above can be achieved.

[0014] Furthermore, a vehicle, in particular a motor vehicle, is proposed, which comprises a steering system including a steering wheel, a steering sensor assigned to the steering wheel for capturing the displacement position of the steering wheel, a torque sensor assigned to the steering wheel for capturing the torque, and a calculation unit arranged for determining a torque for each of different displacement positions of the steering wheel and generating a torque characteristic quantity therefrom, the calculation unit arranged for comparing the torque characteristic quantity with a reference characteristic quantity for calibration and / or initialization of the steering sensor. The steering system here can be configured as a conventional steering system, in particular as an electric power steering, and can include mechanical feed-throughs. However, preferably, the steering system is configured as a steer-by-wire steering system, in particular including an operating unit and at least one wheel turning angle regulator that is mechanically separated from the operating unit and arranged for changing the wheel turning angle of at least one wheel as a function of the steering setting. This makes it possible to achieve, in particular, the advantages already mentioned above.

[0015] The method, control device and vehicle for calibrating and / or initializing a steering sensor should not be limited to the above-mentioned applications and embodiments. In particular, the method, control device and vehicle for calibrating and / or initializing a steering sensor may have a number of individual elements, parts and units different from the number of individual elements, parts and units listed in this specification in order to fulfill the functions described in this specification.

[0016] Further advantages will become apparent from the following description of the drawings, in which an embodiment of the invention is shown. [Brief description of the drawings]

[0017] [Figure 1a] FIG. 1 is a schematic diagram illustrating a vehicle having a steering system configured as an exemplary steer-by-wire steering system. [Figure 1b] FIG. 1 is a schematic diagram illustrating a vehicle having a steering system configured as an exemplary steer-by-wire steering system. [Figure 2a] FIG. 2 is an exemplary diagram illustrating various signals for calibrating and / or initializing a steering sensor of a steering system. [Figure 2b] FIG. 2 is an exemplary diagram illustrating various signals for calibrating and / or initializing a steering sensor of a steering system. [Diagram 3] 4 is an exemplary flow chart including the main method steps of a method for calibrating and / or initializing a steering sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Description of the embodiment 1a and 1b show a schematic representation of a vehicle 14, exemplarily configured as a passenger car, with a number of wheels 32 and a steering system 12. The steering system 12 has an operative connection with the wheels 32 and is provided for influencing the direction of travel of the vehicle 14. Furthermore, the steering system 12 is configured in the present case as a steer-by-wire steering system, which transfers the steering setting electrically to the wheels 32 in at least one operating state. In principle, however, the steering system can also be configured as a conventional steering system, in particular as an electric power steering system.

[0019] The steering system 12 comprises a wheel turning angle adjuster 34, which is known per se. The wheel turning angle adjuster 34 is configured, for example, as a central adjuster. The wheel turning angle adjuster 34 has an active connection with at least two wheels 32, in particular the two front wheels, and is provided for converting the steering setting into a steering movement of the wheels 32. For this purpose, the wheel turning angle adjuster 34 comprises a steering adjustment element 36, which is configured, for example, as a rack, and an actuator unit 38 which cooperates with the steering adjustment element 36. The actuator unit 38 is configured as a steering actuator, in particular as an electric motor, and is provided for driving and controlling the steerable wheels 32. In principle, the steering system can of course also comprise several wheel turning angle adjusters, which are configured, in particular, as single wheel adjusters. Furthermore, the actuator unit can also comprise several electric motors. It is also possible for the wheel turning angle adjuster to be configured, in principle, as a conventional steering gear and to be mechanically connected to the steering wheel via a steering shaft.

[0020] Furthermore, the steering system 12 comprises an operating unit 40, which can be operated in particular by the driver and / or passengers. The operating unit 40 is configured mechanically separated from the wheel turning angle regulator 34. The operating unit 40 is connected purely electrically to the wheel turning angle regulator 34. The operating unit 40 comprises a steering wheel 16, for example in the form of a steering wheel, and a further actuator unit 26, which is in particular mechanically coupled to the steering wheel 16. The further actuator unit 26 is configured as a feedback actuator and is provided for generating at least a steering resistance and / or a reset moment at the steering wheel 16. For this purpose, the further actuator unit 26 comprises at least one electric motor (not shown), which is in particular configured as a permanently excited synchronous motor.

[0021] The operating unit 40 also comprises at least one torsion element 42, in the present case in particular a torsion bar, which is provided for rotating depending on the movement of the steering wheel 16. Alternatively, the steering wheel can also be configured as a joystick, a joystick and / or a joystick ball, etc. Furthermore, the further actuator unit can also comprise a number of electric motors. It is also conceivable to interconnect the operating unit and the wheel steering angle regulator, for example by means of a steering shaft, as in conventional steering systems. In this case, the further actuator unit can be omitted.

[0022] Furthermore, the steering system 12 comprises at least one torque sensor 18, which in the present case is part of an operating unit 40 and is arranged in particular in the region of the torsion element 42. The torque sensor 18 is assigned here to the steering wheel 16. The torque sensor 18 is provided for capturing a torque which is generated by the steering wheel 16 and which is correlated to a rotation of the torsion element 42. In principle, however, the torque sensor can also be configured separately from the operating unit, as for example in conventional steering systems.

[0023] The steering system 12 further comprises at least one steering sensor 10, which in the present case is part of the operating unit 40. The steering sensor 10 is here assigned to the steering wheel 16. The steering sensor 10 is provided for capturing the displacement position of the steering wheel 16. In the present case, the steering sensor 10 is exemplarily configured as a steering angle sensor and is provided for capturing the steering angle. In principle, however, the steering sensor can also be configured separately from the operating unit, as in, for example, conventional steering systems. It is also conceivable to arrange the steering sensor directly on the steering wheel.

[0024] The vehicle 14 further comprises a control device 28, which in the present invention is configured as a central steering control device by way of example and is therefore part of the steering system 12. The control device 28 has an electrical connection to the wheel turning angle regulator 34. The control device 28 further comprises an electrical connection to an operating unit 40, in particular to the torque sensor 18 and the steering sensor 10. The control device 28 is provided for controlling the operation of the steering system 12. In the present invention, the control device 28 is provided for controlling the actuator unit 38 as a function of a signal from the operating unit 40, for example as a function of the steering setting and / or the manual torque. The control device 28 is further provided for controlling the further actuator unit 26 as a function of a signal from the wheel turning angle regulator 34.

[0025] For this purpose, the control device 28 comprises a calculation unit 30. The calculation unit 30 comprises at least one processor (not shown), for example in the form of a microprocessor, and at least one operating memory (not shown). The calculation unit 30 also comprises at least one operating program stored in the operating memory, which comprises at least one control routine, at least one calculation routine, at least one calculation routine and at least one calibration routine. In principle, it is also possible for the vehicle to comprise several control devices. In that case, a first control device with at least one first calculation unit is assigned to the operating unit, whereas a second control device with at least one second calculation unit is assigned to the wheel steering angle regulator. In this case, the first and second control devices can electrically communicate with each other. Furthermore, it is also possible for one control device to be configured as a central control device, for example of the vehicle, which is separate from the steering system.

[0026] The sensors used are essentially safety critical components. Therefore, in order to avoid errors during driving operation, the torque sensor 18 and the steering sensor 10 must be particularly precisely calibrated and / or configured. The following description now focuses on the calibration and / or initialization of the steering sensor 10.

[0027] Therefore, in the following, a method is described for calibrating and / or initializing the steering sensor 10 in order to increase the operating reliability and / or improve the functional form. The method is here in particular implemented during operation of the steering system 12 and thus of the steering sensor 10 in the vehicle 14, i.e. preferably implemented in the stationary state of the vehicle 14. In order to carry out the calibration and / or initialization of the steering sensor 10, the vehicle 14 may comprise a special service operating mode which can be activated, for example, by the driver and / or passengers of the vehicle 14 or by a service person, for example by means of an on-board computer. The execution of the method can here essentially be repeated at regular time intervals or depending on the situation, for example at each system start or as required. In the case of the present invention, in particular the calculation unit 30 is provided for carrying out the method and for this purpose contains a computer program with in particular corresponding program code means. However, it is alternatively also possible to provide a first calculation unit of the first control device, which is assigned to an operating unit, for carrying out the method. Further, the method may alternatively or additionally be performed during a driving mode of the vehicle 14, for example during an automated driving mode.

[0028] In the present invention, for the calibration and / or initialization of the steering sensor 10, the torque characteristic quantity 20 is determined by determining a torque for each of a number of different displacement positions of the steering wheel 16 using the torque sensor 18. In the present invention, the corresponding torques are determined for at least 30 different displacement positions of the steering wheel 16, which are evenly distributed over the entire displacement range of the steering wheel 16, i.e., in the present case, over one complete revolution of the steering wheel 16 configured as a steering wheel. For this purpose, the steering wheel 16 is automatically and / or automatically displaced by the drive control of the further actuator unit 26, and the corresponding torque is determined by the torque sensor 18 when the respective displacement position is reached. Furthermore, the value corresponding to the torque is stored together with the corresponding displacement position as a value pair, for example in the operating memory of the calculation unit 30. The torque characteristic quantity 20 thus comprises a number of value pairs of the displacement positions of the steering wheel 16 and the associated torques. Preferably, the torque characteristic quantity 20 is present here as a vector. Furthermore, in order to be able to determine the torque characteristic quantity 20 independently of external influences, the torque characteristic quantity 20 is determined at times and / or in states where no contact connection with the steering wheel 16 occurs and / or is not made, in particular in so-called hand-off states.

[0029] The torque characteristic quantity 20 is then compared with a reference characteristic quantity 22 for the calibration and / or initialization of the steering sensor 10. This reference characteristic quantity 22 is likewise preferably present as a vector. On the basis of this comparison, the difference and / or deviation between the torque characteristic quantity 20 and the reference characteristic quantity 22 is then determined and used for the calibration and / or initialization of the steering sensor 10. As the reference characteristic quantity 22, in the present invention, a work set quantity applied to the torque characteristic quantity 20 is used, which may in particular have been determined beforehand by means of test measurements and which may be stored, for example, in the operating memory of the calculation unit 30.

[0030] Furthermore, for the comparison of the torque characteristic quantity 20 with the reference characteristic quantity 22, a Fourier transformation is used, in the present case in particular a fast Fourier transformation (FFT). In so far as the torque characteristic quantity 20 corresponds to an almost perfect sinusoidal signal, the calibration and / or initialization of the steering sensor 10 can be carried out directly on the basis of the result of the Fourier transformation. In this case, on the basis of the actual and virtual ratios, in particular the angular ratios, of the result of the Fourier transformation, the difference and / or deviation between the torque characteristic quantity 20 and the reference characteristic quantity 22 can be determined and used for the calibration and / or initialization of the steering sensor 10. However, as a rule, the torque characteristic quantity 20 deviates more or less significantly from the corresponding sinusoidal signal, for example on the basis of system-inherent deviations or corresponding errors. In this case, a deviated evaluation can be considered. Here, a cross-correlation 24 is used for the comparison of the torque characteristic quantity 20 with the reference characteristic quantity 22. For this purpose, a cross-correlation 24 between the torque characteristic quantity 20 and the reference characteristic quantity 22 is calculated and, based on the maximum value of this cross-correlation 24, the difference and / or deviation between the torque characteristic quantity 20 and the reference characteristic quantity 22 is determined. The difference and / or the deviation thus determined can then be used for the calibration and / or initialization of the steering sensor 10. The characteristic of the torque characteristic quantity 20, which repeats periodically over the entire displacement range of the steering wheel 16, in this connection allows the calculation of the cross-correlation using a fast Fourier transform (FFT) and an inverse function for the fast Fourier transform (IFFT). The cross-correlation 24 is calculated using the cross-correlation function k according to the following relationship: k=IFFT(FFT (reference characteristic quantity) · FFT (torque characteristic quantity)) holds true.

[0031] 2a and 2b show exemplary diagrams of various signals for the calibration and / or initialization of the steering sensor 10. FIG.

[0032] In Fig. 2a, the torque is plotted on the vertical axis 44 in [Nm]. On the horizontal axis 46, the displacement of the steering wheel 16 is shown, in the present invention, particularly in the form of a steering angle in [°]. Fig. 2a shows here particularly the entire displacement range of the steering wheel 16. A characteristic curve 48 shows the course of the torque characteristic variable 20. A characteristic curve 50 shows the course of the reference characteristic variable 22 which corresponds to the torque characteristic variable 20.

[0033] On the basis of the profile of the torque characteristic quantity 20, it can be seen that the torque determined by means of the torque sensor 18 varies as a function of the displacement position of the steering wheel 16. For this reason, the torque is determined for a number of different displacement positions of the steering wheel 16, which are then selected in this case in such a way that they are evenly distributed over the entire displacement range of the steering wheel 16. Furthermore, since the profiles of the torque characteristic quantity 20 and the reference characteristic quantity 22 deviate relatively strongly from a sinusoidal signal in the illustrated case, a cross-correlation 24 is used in this case for comparing the torque characteristic quantity 20 with the reference characteristic quantity 22.

[0034] In Fig. 2b, the vertical axis 52 is configured as a variable axis, whereas on the horizontal axis 54 the displacement of the steering wheel 16 is plotted, in the present invention particularly in the form of a steering angle in [°]. A characteristic curve 56 shows in this case the cross-correlation 24 calculated from the torque characteristic quantity 20 and the reference characteristic quantity 22.

[0035] On the basis of the illustrated cross-correlation 24, in particular on the basis of the maximum value of the cross-correlation 24, the difference and / or deviation between the torque characteristic quantity 20 and the reference characteristic quantity 22 can be easily determined. The difference and / or the deviation thus determined can then be used for the calibration and / or initialization of the steering sensor 10.

[0036] Finally, in FIG. 3 an exemplary flow chart is shown including the main method steps of a method for calibration and / or initialization of the steering sensor 10.

[0037] Method step 60 corresponds to a calculation step, in which the torque characteristic quantity 20 is determined. In this case, first a service operating mode is activated, followed by determining a torque for each of a number of different displacement positions of the steering wheel 16 in order to determine the torque characteristic quantity 20 by means of the torque sensor 18. For this purpose, the steering wheel 16 is preferably displaced by actuation of the further actuator unit 26, whereupon a corresponding torque is determined by means of the torque sensor 18 when the respective displacement position is reached. Furthermore, a value corresponding to the torque is stored together with the corresponding displacement position as a value pair, for example in an operating memory of the calculation unit 30.

[0038] Method step 62 corresponds to a comparison step, in which the previously determined torque characteristic quantity 20 is compared with a reference characteristic quantity 22 for the calibration and / or initialization of the steering sensor 10. For the comparison of the torque characteristic quantity 20 with the reference characteristic quantity 22, a Fourier transform is used here, in the present case in particular a fast Fourier transform (FFT). Furthermore, a cross-correlation 24 between the torque characteristic quantity 20 and the reference characteristic quantity 22 is calculated and, on the basis of the maximum value of this cross-correlation 24, the difference and / or deviation between the torque characteristic quantity 20 and the reference characteristic quantity 22 is determined.

[0039] Method step 64 corresponds to a calibration and / or initialization step in which the steering sensor 10 is calibrated and / or initialized, whereby differences previously determined, for example by means of a Fast Fourier Transform (FFT) and / or a cross-correlation 24, and / or deviations previously determined, for example by means of a Fast Fourier Transform (FFT) and / or a cross-correlation 24, are used for the calibration and / or initialization of the steering sensor 10.

[0040] The exemplary flow chart of Fig. 3 is merely an exemplary description of a method for calibrating and / or initializing the steering sensor 10. In particular, individual method steps can also be modified or additional method steps can also be added. In this context, for example, it is also conceivable to apply the method accordingly to conventional steering systems, in particular to electric power steering, in which case a steering actuator is used as the actuator unit for assisting the manual moment applied to the steering wheel in this case.

Claims

1. A method for calibrating and / or initializing a steering sensor (10) of a steering system (12), in particular during operation of said steering system (12) in a vehicle (14), comprising: The steering system (12) includes a steering wheel (16) and a torque sensor (18) assigned to the steering wheel (16); The steering sensor (10) is provided for capturing a displacement position of the steering wheel (16), 2. A method for determining a torque characteristic quantity (20) by determining a torque for each of a number of different displacement positions of the steering wheel (16) and comparing the torque characteristic quantity (20) with a reference characteristic quantity (22) for calibration and / or initialization of the steering sensor (10).

2. 2. The method of claim 1, wherein a torque is determined for at least four different displacement positions of the steering wheel (16), the displacement positions being evenly distributed over the entire displacement range of the steering wheel (16).

3. 2. The method according to claim 1, wherein a Fourier transformation, in particular a fast Fourier transformation, is used for the comparison of the torque characteristic quantity (20) with the reference characteristic quantity (22).

4. 2. The method according to claim 1, wherein a cross-correlation (24) is used for comparing the torque characteristic quantity (20) with the reference characteristic quantity (22).

5. 5. The method according to claim 4, further comprising determining a difference and / or deviation between the torque characteristic quantity and the reference characteristic quantity based on the maximum value of the cross-correlation and using the difference and / or deviation for calibrating and / or initializing the steering sensor.

6. 2. The method according to claim 1, wherein the steering system (12) comprises at least one actuator unit (26) in operative connection with the steering wheel (16), the steering wheel (16) being displaced by driving control of the actuator unit (26) in order to determine the torque characteristic quantity (20).

7. 2. The method according to claim 1, wherein the torque characteristic quantity (20) is determined at times and / or in states where no contact connection of the steering wheel (16) occurs and / or is not made, in particular in so-called hand-off states.

8. A control device (28) comprising a computing unit (30) for carrying out the method according to claim 1.

9. In a vehicle (14), in particular a motor vehicle, equipped with a steering system (12) comprising a steering wheel (16), a steering sensor (10) assigned to the steering wheel (16) for capturing a displacement position of the steering wheel (16), and a torque sensor (18) assigned to the steering wheel (16) for capturing a torque, a calculation unit (30) is provided for determining a torque for each of a number of different displacement positions of the steering wheel (16) and generating a torque characteristic quantity (20) therefrom, the calculation unit (30) being provided for comparing the torque characteristic quantity (20) with a reference characteristic quantity (22) for calibration and / or initialization of the steering sensor (10), A vehicle (14).

10. 10. The vehicle (14) of claim 9, wherein the steering system (12) is a steer-by-wire steering system.

11. The vehicle (14) of claim 9, wherein the computing unit (30) is arranged to perform the method of claim 1.

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