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

Abstract

The present disclosure relates to a method for determining a steering damping 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 which is configured to apply a steering torque to the steering device. The method comprises at least the step of determining the steering damping requirement based on at least one rack force of the steering system, wherein the steering damping requirement forms at least a portion of a target steering torque with which the steering device can be acted upon by the at least one actuator.

Claims

1. A method for determining a steering damping 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 configured to apply a steering torque to the steering device, the method comprising: determining a steering damping requirement based on at least one rack force of the steering system, wherein the steering damping requirement forms at least a portion of a target steering torque with which the steering device can be acted upon by the at least one actuator.

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

3. The method according to claim 1, wherein the method further comprises at least the step of: multiplying at least a first function value and a second function value in order to determine the steering damping 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 a vehicle speed, a steering position determined by the steering system and a steering velocity determined by the steering system.

4. The method according to claim 3, wherein at least one of the first to second function values is determined based on at least sectionally defined functions and/or by characteristic curves and/or by characteristic diagrams and/or look-up tables.

5. The method according to claim 4, wherein the at least sectionally defined functions and/or characteristic curves and/or characteristic diagrams and/or look-up tables are variable as a function of a desired steering feel.

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

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

8. 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, the control device being coupled to the actuator, wherein the control device is configured to determine a steering damping requirement of the steering device according to the method according to claim 1, and wherein the steering damping requirement forms at least a portion of a target steering torque with which the steering device can be acted upon by the at least one actuator.

9. The steering system according to claim 8, wherein the control device is configured to determine the steering damping requirement according to the method according to claim 3, wherein the control device comprises at least one processor and is coupled to a memory device, wherein at least sectionally defined functions and/or characteristic curves and/or characteristic diagrams and/or look-up tables are stored in the memory device, so that at least one of the first and second function values can be determined by the control device based on data from the memory device, and wherein the processor is designed to determine the steering damping requirement according to the method according to claim 3.

10. The steering system according to claim 8, wherein the steering system further comprises at least one sensor device configured to measure a rack force applied to the rack.

11. The steering system according to claim 8, wherein the steering system is one of a steering-by-wire steering system and an electromechanical steering system.

12. A computer program product, comprising instructions which, when the program is executed by a computer, cause the computer to determine the steering damping requirement according to the method according to claim 1.

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

14. The method according to claim 2, wherein the method further comprises at least the step of: multiplying at least a first function value and a second function value in order to determine the steering damping 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 the vehicle speed, the steering position determined by the steering system and a steering velocity determined by the steering system.

15. The method according to claim 14, wherein at least one of the first to second function values is determined based on at least sectionally defined functions and/or by characteristic curves and/or by characteristic diagrams and/or look-up tables.

16. The method according to claim 15, wherein the rack force is based on a measurement, an estimate from a steering model or on a vehicle model and is provided.

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 taken from 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 illustration of the determination of a total steering torque requirement according to the prior art,

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

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

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

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

DETAILED DESCRIPTION

[0081] FIG. 2 is a simplified schematic illustration 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 axle 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 feedback 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 coupled to a tie rod 44A, 44B. A toothed 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 the wheels 40A, 40B to deflect relative to their normal position.

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

[0085] There is also a second sensor 52. The second sensor 52 is configured 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 configured to measure the rotational velocity of the wheel carrier 42A relative 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 velocity represents a steering velocity 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 to the sensors 50, 52. The sensors 50, 52 transmit corresponding measured values for a rack force, the steering position and the steering velocity to the control device 54. The control unit also receives information about the vehicle speed. The vehicle speed can optionally also be determined by the sensor 52 or by other suitable devices. The control device 54 is configured 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 sectionally 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 configured 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 thereto 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 illustration of a determination of the steering return torque requirement according to one exemplary arrangement 60.

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

[0091] In block 70, a third function value is determined based on a steering position Pos 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 block 74 by the product value from block 68, i.e. the base target velocity. As a result, the steering return torque requirement can be determined in block 76.

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

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

[0094] In block 82, a first function value is determined as a function of the rack force RackF. In block 84, a second function value is determined based on the vehicle speed Vspd. The first and second function values are multiplied in 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 block 90 based on the steering position Pos determined by the steering system, the steering velocity Vel determined by the steering system and the limit value determined beforehand. As an additional input variable for determining the third function value, block 90 comprises a feedback loop, so that the determined steering hysteresis requirement is also taken into account.

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

[0097] The third and fourth function values are multiplied in block 94 in order to determine the absolute slope 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 slope, so that the situation-dependent steering hysteresis requirement is determined in block 98.

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

[0100] FIG. 5 is a simplified schematic illustration of the determination of the steering damping requirement according to one exemplary arrangement 100.

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

[0102] The blocks 102, 108 can include at least sectionally defined functions and/or characteristic values and/or characteristic diagrams and/or reference tables in order to be able to adapt the values determined in each case to a desired driving experience.

[0103] While the disclosure has been illustrated and described with respect to one or more implementations, upon reading and understanding this specification and the accompanying drawings, those skilled in the art 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, that feature may be combined with one or more other features of the other implementations.