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DE-102024133187-A1 - Method for the cooperative control of a steer-by-wire steering system of a motor vehicle, steer-by-wire steering system and motor vehicle

DE102024133187A1DE 102024133187 A1DE102024133187 A1DE 102024133187A1DE-102024133187-A1

Abstract

The disclosure generally relates to a method (50) for the cooperative control of a steer-by-wire steering system (12) of a motor vehicle (10), a steer-by-wire steering system (12), and a motor vehicle (10). The steer-by-wire steering system (12) comprises at least a steering wheel (20), a steering wheel actuator (34) coupled to the steering wheel (20), a steering wheel sensor (38), a road wheel actuator (26) coupled to at least one steerable vehicle wheel (22) of the motor vehicle (10), and a control device (40). The control device (40) is coupled to at least the steering wheel actuator (34), the steering wheel sensor (38), and the road wheel actuator (26). The control device (40) executes at least one algorithm (44) for controlling the steering wheel actuator and the road wheel actuator and is coupled to a higher-level vehicle control device (16). The higher-level vehicle control device (16) performs at least a semi- or fully automatic path-following function (18). A target angle request for an initial target angle for the steering wheel (20) is received by the control device (40) from the higher-level vehicle control device (16) based on the path-following function (18). The steering wheel (20) is controlled by the control device (40) such that it is adjusted to the target angle by means of the steering wheel actuator (34). The steering wheel (20) can be adjusted to a different steering wheel angle by the driver using an additional driver torque. The steering wheel angle is detected by the steering wheel sensor (38). The steering wheel (20) is acted upon by the control device (40) with a feedback torque via the steering wheel actuator (34). The feedback torque depends on the difference between the actual detected steering wheel angle and the initial target angle.

Inventors

  • Oliver Nehls
  • Sergio Codonesu
  • Alexander Ein Waldt
  • Hannah Denomme

Assignees

  • FORD GLOBAL TECHNOLOGIES, LLC

Dates

Publication Date
20260513
Application Date
20241113

Claims (13)

  1. Method (50) for the cooperative control of a steer-by-wire steering system (12) of a motor vehicle (10) comprising at least a steering wheel (20), a steering wheel actuator (34) coupled to the steering wheel (20), a steering wheel sensor (38), a road wheel actuator (26) coupled to at least one steerable vehicle wheel (22) of the motor vehicle (10), and a control device (40), wherein the control device (40) is coupled at least to the steering wheel actuator (34), the steering wheel sensor (38), and the road wheel actuator (26), wherein the control device (40) executes at least one algorithm (44) for controlling the steering wheel actuator and the road wheel actuator and is coupled to a higher-level driving control device (16), wherein the higher-level driving control device (16) performs at least a semi- or fully automatic path following functionality (18), wherein the method (50) comprises at least the following steps: - Receiving a Target angle requirement of a - the control device (40) determines the original target angle for the steering wheel (20) from the higher-level driving control device (16) based on the path following functionality (18), - the control device (40) adjusts the steering wheel (20) by means of the steering wheel actuator (34) according to the target angle, wherein the steering wheel (20) can be adjusted by the driver to a different steering wheel angle with an additional driver torque, - the steering wheel sensor (38) detects a steering wheel angle, - the control device (40) applies a feedback torque to the steering wheel (20) by means of the steering wheel actuator (34), wherein the feedback torque depends on a difference between the actual detected steering wheel angle and the original target angle, - the control device determines a wheel target angle for at least one steerable vehicle wheel of the motor vehicle based on the actually detected steering wheel angle, - the control device determines an actuation signal for the road wheel actuator corresponding to the wheel target angle, and - Output of the control signal to the road wheel actuator.
  2. Procedure (50) according to Claim 1 , characterized in that the control device (40) returns the steering wheel (20) to the target angle by means of the steering wheel actuator (34) if a driver ends an application of an additional driver torque to the steering wheel (20).
  3. Procedure (50) according to Claim 1 or 2 , characterized in that the torque capability of the steering wheel actuator (34) is limited by the control device (40).
  4. Method according to one of the preceding claims, characterized in that the feedback torque is limited based on a maximum permissible feedback torque of the steering wheel actuator (34).
  5. Procedure (50) according to Claim 4 , characterized in that, if the driver applies a driver torque to the steering wheel (20) in such a way that no feedback can be provided for a portion of the driver torque in the form of an excessive torque, since the feedback torque corresponds to the maximum permissible feedback torque, the target angle of the steering wheel (20) is adjusted by the control device (40) to an adapted target angle until the feedback torque is less than the maximum permissible feedback torque of the electric motor (36) of the steering wheel actuator (34).
  6. Procedure (50) according to Claim 4 , characterized in that the control device (40) sums the actual target angle with a portion of a target angle difference between the actual target angle and the original target angle corresponding to the target angle requirement in each control period to adjust an actual target angle to the target angle corresponding to the target angle requirement.
  7. Procedure according to Claim 6 , characterized in that the control device (40) sums the actual target angle with a component of a target angle difference between the actual target angle and the original target angle corresponding to the target angle requirement only if the feedback torque is less than the maximum permissible feedback torque of the electric motor (36) of the steering wheel actuator (34).
  8. Procedure (50) according to Claim 3 , characterized in that the control device (40) returns the steering wheel (20) to the target angle by means of the steering wheel actuator (34) based on a basic steering feel algorithm, wherein the basic steering feel algorithm is also used when controlling the steering wheel (20) according to the target angle in the case of exclusively manual steering.
  9. Procedure (50) according to Claim 8 characterized in that the control device (40) for adjusting an actual target angle to the target angle corresponding to the target angle requirement sums the actual target angle with a portion of a target angle difference between the actual target angle and the original target angle corresponding to the target angle requirement in each control period, if the feedback torque is less than the maximum permissible feedback torque of the electric motor (36) of the steering wheel actuator (34).
  10. Method (50) according to one of the preceding claims, characterized in that the control device (40) determines a wheel target angle for at least one steerable vehicle wheel (22) based on the detected steering wheel angle and outputs a control signal corresponding to the wheel target angle to the road wheel actuator (26).
  11. Procedure (50) according to Claim 10 , characterized in that the control device (40) determines the wheel target angle at least on the basis of a lookup table, optionally additionally using a detected or determined The vehicle speed of the motor vehicle (10) is taken into account, or that the control device (40) determines the wheel target angle at least on the basis of an algorithm of the manual control mode, which is also used in determining the wheel target angle in the case of exclusively manual steering.
  12. Steer-by-wire steering system (12) for a motor vehicle (10) comprising at least a steering wheel (20), a steering wheel actuator (34) coupled to the steering wheel (20), a steering wheel sensor (38), a road wheel actuator (26) coupled to at least one steerable vehicle wheel (22) of the motor vehicle (10), and a control device (40), wherein the control device (40) is coupled at least to the steering wheel actuator (34), the steering wheel sensor (38), and the road wheel actuator (26), wherein the control device (40) executes at least one algorithm (44) for controlling the steering wheel actuator and the road wheel actuator and for cooperative control, and is coupled to a higher-level driving control device (16), whereby the higher-level driving control device is configured at least to execute at least one semi- or fully automatic path following functionality (18), whereby the control device (40) is configured at least to: - a to receive a target angle request of an initial target angle for the steering wheel (20) from the higher-level driving control device (16) based on the path following functionality (18), - to control the steering wheel (20) such that the steering wheel (20) is adjusted by means of the steering wheel actuator (34) according to the target angle, wherein the steering wheel (20) can be adjusted by the driver to a different steering wheel angle with an additional driver torque, wherein the steering wheel sensor (38) is configured to detect a steering wheel angle, and in which the control device (40) is configured at least to: - apply a feedback torque to the steering wheel (20) by means of the steering wheel actuator (34), wherein the feedback torque depends on a difference between the actual detected steering wheel angle and the initial target angle, - determine a wheel target angle for at least one steerable vehicle wheel of the motor vehicle based on the actually detected steering wheel angle, - determine a control signal for the road wheel actuator corresponding to the wheel target angle, and the To send a control signal to the road wheel actuator.
  13. motor vehicle (10) with a steer-by-wire steering system (12) according to Claim 12 or a steer-by-wire steering system (12) which is implemented according to the method (50) according to one of the Claims 1 until 11 is operational.

Description

The disclosure generally relates to a method for the cooperative regulation of a steer-by-wire steering system of a motor vehicle, a steer-by-wire steering system and a motor vehicle. Modern motor vehicles possess advanced features, such as path-following functions, which allow the vehicle's path to be controlled semi-autonomously or fully autonomously. For such vehicles, the driver has at least two options for interacting with the path-following function in relation to the electrically assisted power steering. On the one hand, the driver can typically completely disengage the lane-following function, for example by using a switch, pressing the speed reduction pedal, or applying a torque to the steering wheel that is greater than a predetermined torque threshold, thus restoring full steering control to the driver. On the other hand, the driver can typically override the steering wheel's target angle, defined by the path-following function, by applying a desired steering wheel angle. As soon as the driver releases the steering wheel, the vehicle resumes following the external angle input defined by the path-following function. The ability to influence the vehicle's lateral control without completely overriding it is generally referred to as "cooperative control." In addition, modern motor vehicles often feature steer-by-wire steering systems (hereinafter referred to as SBW steering systems), which represent an emerging steering technology. This eliminates the direct mechanical connection between the steering wheel and the vehicle wheel. This connection is replaced by two actuators: a steering wheel actuator with feedback, which generates a feedback torque at the steering wheel for the driver, and a road wheel actuator, which controls at least one, but typically several, steerable vehicle wheels into the desired position. The feedback torque provides the driver with a sense of the vehicle's lateral stability. To determine the feedback torque corresponding to the vehicle's lateral stability, the SBW steering system includes a control device that executes a so-called "basic feedback algorithm." Since SBW steering systems have significant differences compared to previous mechanically coupled steering systems, such as EPS steering systems (EPS: “Electric Power Steering”), for example with regard to possible independent control of the steering wheel and road wheels, the previous approaches to cooperative control are not readily transferable. There is therefore a need to be able to use SBW steering systems within a cooperative control framework. In particular, there is a need to be able to make steering inputs simultaneously by the driver and according to a path-following function, whereby the vehicle's lateral control should be regulated according to a smooth transition between these input methods in order to increase driver comfort compared to previous approaches. The problem is solved by the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims and the subsequent description, each of which, individually or in (sub-)combination, can represent aspects of the disclosure. Some features are explained with regard to methods, others with regard to apparatus. However, the corresponding aspects are interchangeable. According to one aspect, some embodiments of the disclosure relate to a method for the cooperative control of a self-steering vehicle (SBW) steering system of a motor vehicle. The SBW steering system comprises at least a steering wheel, a steering wheel actuator coupled to the steering wheel, a steering wheel sensor, a road wheel actuator coupled to at least one steerable wheel of the motor vehicle, and a control device. The control device is coupled to at least the steering wheel actuator, the steering wheel sensor, and the road wheel actuator. The control device executes at least one algorithm for controlling the steering wheel actuator and the road wheel actuator and is coupled to a higher-level vehicle control device. The higher-level vehicle control device performs at least a semi- or fully automatic path-following function. The method comprises at least the following steps: - A target angle request of an initial target angle for the steering wheel is received by the control device from the higher-level vehicle control device based on the path following functionality, The steering wheel is controlled by the control device such that it is adjusted to the target angle by means of the steering wheel actuator. The steering wheel can be adjusted by the driver with an additional turn of the steering wheel. moment adjustable to a different steering wheel angle , - The steering wheel angle is detected by the steering wheel sensor, - The steering wheel is subjected to a feedback torque by the control device via the steering wheel actuator. The feedback torque depends on the difference between the actual detected steering wheel angle and the original target angle.