METHOD FOR DETERMINING A STEERING HYSTERESIS REQUIREMENT, STEERING SYSTEM, COMPUTER PROGRAM PRODUCT AND STORAGE MEDIUM

Abstract

The present disclosure relates to a method for determining a steering hysteresis requirement of a steering device of a vehicle, a steering system, a computer program product and a computer-readable storage medium. The steering device is part of a steering system of the vehicle and is coupled to at least one actuator. The actuator is set up to apply a steering torque to the steering device. The method comprises at least the step of determining the steering hysteresis requirement based on at least one rack force of the steering system. The steering hysteresis requirement forms at least a component of a target steering torque which can be applied to the steering device by the at least one actuator.

Claims

1. A method for determining a steering hysteresis requirement of a steering device of a vehicle, wherein the steering device is part of a steering system of the vehicle and is coupled to at least one actuator which is set up to apply a steering torque to the steering device, the method comprising the step of: determining the steering hysteresis requirement based on at least one rack force of the steering system, wherein the steering hysteresis requirement forms at least a component of a target steering torque which can be applied to the steering device by the at least one actuator.

2. The method according to claim 1, wherein the steering hysteresis requirement is further determined based at least on one of a vehicle speed, on a steering position determined by the steering system of the vehicle and on a steering speed determined by the steering system.

3. The method according to claim 1, wherein the steering hysteresis requirement is characterized by an absolute limit value and an absolute gradient value, and wherein the rack force is taken into account both when determining the absolute limit value and also when determining the absolute gradient value of the steering hysteresis requirement.

4. The method according to claim 3, wherein the method further comprises the steps of: multiplying at least a first function value and a second function value in order to determine the absolute limit value of the steering hysteresis requirement, wherein the first function value is determined at least as a function of the rack force, and wherein the second function value is determined at least as a function of thea vehicle speed, and multiplying a third function value and a fourth function value in order to determine the absolute gradient value of the steering hysteresis requirement, wherein the third function value depends on at least the absolute limit value of the steering hysteresis requirement, thea steering position determined by the steering system, a steering speed determined by the steering system and the steering hysteresis requirement, and wherein the fourth function value is determined as a function of at least the vehicle speed.

5. The method according to claim 4, wherein at least one of the first to fourth function values is determined based on at least partially defined functions and/or characteristic curves and/or characteristic fields and/or look-up tables.

6. The method according to claim 5, wherein the at least partially defined functions and/or characteristic curves and/or characteristic fields and/or look-up tables are variable as a function of a desired steering feel.

7. The method according to claim 1, wherein the rack force is provided, based on a measurement, on an estimate from a steering model or on a vehicle model.

8. The method according claim 1, wherein the method is computer-implemented.

9. A steering system for a vehicle, wherein the steering system comprisingcomprises at least one steering device, a rack, a control device and at least one actuator, wherein the control device is coupled to the actuator, wherein the control device is set up to determine a steering hysteresis requirement of the steering device according to the method according to claim 4, and wherein the steering hysteresis requirement forms at least a component of a target steering torque which can be applied to the steering device by the at least one actuator.

10. The steering system according to claim 9, wherein the control device comprises at least one processor and is coupled to a memory device, wherein at least partially defined functions and/or characteristics and/or characteristic fields and/or look-up tables are stored in the memory device, so that at least one of the first to fourth function values can be determined by the control device based on data from the memory device, and wherein the processor is designed so that it determines the steering hysteresis requirement.

11. The steering system according to claim 9, wherein the steering system further comprises at least one sensor by which a rack force applied to the rack can be measured.

12. The steering system according to claim 9, wherein the steering system is a steering-by-wire steering system.

13. A computer program product, comprising commands which, when the program is executed by a computer, cause the computer to determine the steering hysteresis requirement according to the method according to claim 1.

14. A computer-readable storage medium, comprising commands which, when the program is executed by a computer, cause the computer to determine a steering hysteresis requirement based on at least one rack force of the steering system.

15. The method according to claim 2, wherein the steering hysteresis requirement is characterized by an absolute limit value and an absolute gradient value, and wherein the rack force is taken into account both when determining the absolute limit value and also when determining the absolute gradient value of the steering hysteresis requirement.

16. A steering system for a vehicle, wherein the steering system comprises at least one steering device, a rack, a control device and at least one actuator, wherein the control device is coupled to the actuator, wherein the control device is set up to determine a steering hysteresis requirement of the steering device according to the method according to claim 1, and wherein the steering hysteresis requirement forms at least a component of a target steering torque which can be applied to the steering device by the at least one actuator.

17. The steering system according to claim 9, wherein the steering system is an electromechanical steering system.

18. The method according to claim 4, wherein the rack force is provided, based on a measurement, on an estimate from a steering model or on a vehicle model.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0075] The disclosure and further advantageous exemplary arrangements and developments thereof are described and explained in more detail below with reference to the examples shown in the drawings. The features to be seen in the description and the drawings can be used individually or collectively in any combination according to the disclosure. In the drawings:

[0076] FIG. 1 is a simplified schematic representation of the determination of a total steering torque requirement according to the prior art,

[0077] FIG. 2 is a simplified schematic representation of a steering system,

[0078] FIG. 3 is a simplified schematic representation of the determination of the steering return torque requirement according to one exemplary arrangement,

[0079] FIG. 4 is a simplified schematic representation of the determination of the steering hysteresis requirement according to one exemplary arrangement, and

[0080] FIG. 5 is a simplified schematic representation of the determination of the steering damping requirement according to one exemplary arrangement.

DETAILED DESCRIPTION

[0081] FIG. 2 is a simplified schematic representation of a steering system 30. The steering system 30 comprises a steering device 32, in this case a steering wheel. The steering device 32 is coupled to an axle 34. An actuator 36 which interacts with the axis 34 is arranged on the axle. A manipulated variable can be applied to the actuator 36 in order to exert a torque on the axle 34 in accordance with the manipulated variable and thus to report a desired steering feel to the driver.

[0082] The steering device 32 and its axle 34 are mechanically separated from the rest of the steering system 30, of which the steerable wheels 40A, 40B are shown here by way of example. The wheels 40A, 40B are each coupled to a wheel carrier 42A, 42B, which in turn are in each case coupled to a tie rod 44A, 44B. A rack 46 is arranged between the tie rods 44A, 44B. The rack 46 provides a mechanical coupling for the wheels 40A, 40B so that they are always aligned parallel to one another.

[0083] An actuator 48 (pinion) is coupled to the rack 46 and can move the rack out of its central position in order to cause a deflection of the wheels 40A, 40B relative to their normal position.

[0084] A sensor 50 which measures the rack force is also coupled to the rack 46. For example, the sensor 50 can be a strain gauge.

[0085] There is also a second sensor 52. The second sensor 52 is set up to determine a relative position of the wheel carrier 42A relative to its normal position. This relative position represents a steering position determined by the steering system of the vehicle. The sensor 52 is also set up to measure the rotational speed of the wheel carrier 42A with respect to the center of rotation when the position of the wheel 40B changes. Of course, this does not mean the wheel rotation, but the steering rotation. This rotational speed represents a steering speed determined by the steering system of the vehicle.

[0086] The steering system further comprises a control device 54 having a processor. The control device 54 is coupled both to the actuator 36 and also to the sensors 50, 52. The sensors 50, 52 transmit corresponding measured values for the rack force, the steering position and the steering speed to the control device 54. The control device also receives information about the vehicle speed. The vehicle speed can optionally also be determined by the sensor 52 or by suitable other devices. The control device 54 is set up to determine at least a steering return torque requirement and/or a steering hysteresis requirement and/or a steering damping requirement based on the information received. Alternatively, or cumulatively, the control device 54 can also determine a total target torque requirement from a desired combination of the individual torques.

[0087] The control device 54 can optionally be coupled to a memory device in which partially defined functions, characteristic values or reference tables can be stored in order to be able to use them in the determination by the control device 54.

[0088] Optionally, the control device 54 can be set up to compare the specific steering torque requirement with an actual steering torque. A manipulated variable for the actuator 36 can then be determined and transmitted to the actuator in order to match the actual steering torque to the steering torque requirement. In any case, the specific steering torque requirement is the variable on which the control of the actuator 36 is based, in order to convey the desired steering feel to the driver.

[0089] FIG. 3 is a simplified schematic representation of the determination of the steering return torque requirement according to one exemplary arrangement 60.

[0090] A first function value is determined in the block 62 as a function of a steering position Pos, which is determined by the steering system of the vehicle, and the vehicle speed Vspd. A second function value is determined in the block 64 as a function of the rack force RackF. The first and second function values are multiplied in the block 66 to determine a product value. The steering speed Vel determined by the steering system of the vehicle is then subtracted from the product value in the block 68. In this way a base target speed is determined.

[0091] In the block 70 a third function value is determined based on a steering position Pos, which is determined internally by the steering system or externally in the vehicle, and the vehicle speed Vspd. In block 72, a fourth function value is determined based on the rack force RackF. The third and fourth function values represent a proportionality factor. The third and fourth function values are then multiplied in the block 74 by the product value from the block 68, that is to say the base target speed. As a result, the steering return torque requirement can be determined in the block 76.

[0092] The blocks 62, 64, 70, 72 can comprise at least partially defined functions and/or characteristic values and/or characteristic fields and/or reference tables in order to be able to adapt the values determined in each case to a desired driving feel.

[0093] FIG. 4 is a simplified schematic representation of the determination of the steering hysteresis requirement according to an exemplary arrangement 80.

[0094] In the block 82, a first function value is determined as a function of the rack force RackF, In the block 84, a second function value is determined based on the vehicle speed Vspd. The first and second function values are multiplied in the block 86. As a result, an absolute limit value (Limit) of the steering hysteresis requirement is determined.

[0095] In addition, a third function value is determined in the block 90 based on the steering position Pos determined by the steering system, the steering speed Vel determined by the steering system and the limit value determined beforehand. As an additional input variable for determining the third function value, the block 90 comprises a feedback loop, so that the determined steering hysteresis requirement is also taken into account.

[0096] In the block 92, a fourth function value is determined based on he rack force RackF.

[0097] The third and fourth function values are multiplied in the block 94 in order to determine the absolute gradient value (Slope) of the steering hysteresis requirement,

[0098] As a result, the steering hysteresis requirement is determined both in the limit value and in the gradient, so that the situation-dependent steering hysteresis requirement is determined in the block 98.

[0099] The blocks 82, 84, 90, 92 can comprise at least partially defined functions and/or characteristic values and/or characteristic fields and/or reference tables in order to be able to adapt the values determined in each case to a desired driving feel.

[0100] FIG. 5 shows a simplified schematic representation of the determination of the steering damping requirement according to an exemplary arrangement 100.

[0101] A first function value is determined in the block 102 as a function of a vehicle speed Vspd, a steering position Pos determined by the steering system of the vehicle and a steering speed Vel determined by the steering system of the vehicle. Based on the rack force RackF, a second function value is determined in the block 104. The first and second function values are multiplied in the block 106 in order to determine the steering damping requirement in the block 108.

[0102] The blocks 102, 108 can comprise at least partially defined functions and/or characteristic values and/or characteristic fields and/or reference tables in order to be able to adapt the values determined in each case to a desired driving feel,

[0103] Although the disclosure has been shown and described with respect to one or more implementations, those skilled in the art upon reading and understanding this description and the accompanying drawings will identify equivalent changes and modifications. Furthermore, while a particular feature of the disclosure may have been disclosed in relation to only one of a plurality of implementations, this feature can be combined with one or more other features of the other implementations.