Method for operating a steering system of a vehicle
The disclosure relates to a method for operating a steering system of a vehicle, in particular a motor vehicle, in which the steering system is designed as a steer-by-wire steering system having an at least partially fail-operational operating unit with at least one steering handle and with at least one feedback actuator that interacts with the steering handle, and having at least one wheel steering angle control element, which is operatively connected to the operating unit, for changing a steering angle of at least one vehicle wheel. The method includes changing a steering characteristic of the steering system in at least one operating state in which an initial error of the operating unit is ascertained, and modifying a steering feel in a controlled manner, in particular by means of a feedback actuator operation that is adapted to the initial error.
1 . A method for operating a steering system of a vehicle, in which the steering system is designed as a steer-by-wire steering system and comprises (i) an operating unit with at least one steering handle and with at least one feedback actuator that interacts with the steering handle, and (ii) at least one wheel steering angle control element, which is operatively connected to the operating unit, for changing a steering angle of at least one vehicle wheel, the operating unit being at least partially fail-operational, the method comprising:
ascertaining an initial error of the operating unit; and
changing a steering characteristic of the steering system, in at least one operating state in which the initial error of the operating unit is ascertained, by gradually modifying a steering feel of the at least one steering handle produced by the at least one feedback actuator in a controlled manner from a normal steering feel to a modified steering feel over a fade phase time period.
2 . The method according to claim 1 , wherein the gradual modifying of the steering feel includes using an integrator for cross-fading from the normal steering feel to the modified steering feel, said integrator being activated in the operating state by an error signal correlated with the initial error.
3 . The method according to claim 1 , wherein the fade phase time period is at least 10 s.
4 . The method according to claim 1 , wherein the modified steering feel provides feedback to a driver, said feedback being at least temporarily between the normal steering feel and a passive steering feel without an active feedback torque.
5 . The method according to claim 1 , wherein the modified steering feel has a characteristic which corresponds to a passive steering feel without active feedback torque by the feedback actuator.
6 . The method according to claim 1 , wherein the modified steering feel reproduces a characteristic corresponding to an inherent frictional behavior of the operating unit.
7 . The method according to claim 1 , wherein the modified steering feel does not simulate a centering of the steering handle.
8 . The method according to claim 1 , wherein a maximum torque level of the modified steering feel is above a maximum torque level of a passive steering feel without active feedback torque by the feedback actuator.
9 . The method according to claim 1 , wherein the modified steering feel simulates a damping behavior, the damping behavior being adapted based on a steering speed of the steering handle and/or a vehicle speed.
10 . A computing unit comprising:
at least one operating memory; and
at least one processor configured to execute program instructions stored in the at least one operating memory to carry out the method according to claim 1 .
11 . A steering system comprising:
the computing unit according to claim 10 ;
the operating unit, which comprises the at least one steering handle and the at least one feedback actuator that interacts with the steering handle; and
the at least one wheel steering angle control element, which is operatively connected to the operating unit and is configured to control the steering angle of the at least one vehicle wheel.
12 . A vehicle comprising:
the steering system according to claim 11 .
13 . The vehicle according to claim 12 , wherein the vehicle is a motor vehicle.
14 . The steering system according to claim 11 , wherein the steering system is a steer-by-wire steering system in which the at least one wheel steering angle control element is mechanically separate from the at least one operating unit.
15 . The method according to claim 1 , wherein the gradual change from the normal steering feel to the modified steering feel takes place by using a moving average.