US 12,116,051 B2
Degradation concept for a steer-by-wire steering system
Pèter Kakas, Budapest (HU); Yosuke Ojima, Wako (JP); Yuya Tanno, Wako (JP); Takaya Yamaguchi, Wako (JP); and Munetsugu Hanji, Wako (JP)
Assigned to THYSSENKRUPP PRESTA AG, Eschen (LI); and HONDA MOTOR CO., LTD., Tokyo (JP)
Filed by thyssenkrupp Presta AG, Eschen (LI); and Honda Motor Co., Ltd., Tokyo (JP)
Filed on Oct. 19, 2022, as Appl. No. 17/969,007.
Application 17/969,007 is a continuation of application No. PCT/EP2020/061017, filed on Apr. 20, 2020.
Prior Publication US 2023/0040044 A1, Feb. 9, 2023
Int. Cl. B62D 5/04 (2006.01)
CPC B62D 5/0484 (2013.01) 23 Claims
OG exemplary drawing
 
13. A method of controlling a steer-by-wire steering system for a motor vehicle or a steering system for an autonomous driving motor vehicle, the steering system including a controller configured or programmed to control steering of steerable road wheels depending on a driver's input or an input of an autonomous driving unit, and to include operation modes including a normal mode of operation with full steering functionality and no quality problems, a first degraded mode with degraded operation of the steering system, a second degraded mode with degraded operation of the steering system, and a third degraded mode with degraded operation of the steering system, the method comprising:
evaluating a state of performance degradation of the steering system by evaluation to provide an evaluation result; and
setting the controller to the normal mode or to one of the at least two degraded modes based on the evaluation result; wherein
the operation modes each correspond to specific ranges of percentages of a performance limit of the steering system;
the normal mode of operation is in a range between 100% of available performance of the steering system and a first lower limit;
the first degraded mode is in a range between a first upper limit and a second lower limit;
the second degraded mode is in a range between a second upper limit and a third lower limit;
the third degraded mode is in a range between a third upper limit and zero available performance of the steering system;
the first degraded mode provides full steering functionality;
the second degraded mode provides full steering functionality, and the controller of the steering system is configured or programmed to provide a vehicle speed limitation to a vehicle drive controller in the second degraded mode; and
in the third degraded mode, the performance of the steering system is too low to finish the steering maneuvers, the vehicle speed limitation is set to allow the vehicle to safely stop without performance of the steering system while the steering system provides information about its degradation state, and a vehicle level external actuator is used to control lateral movement of the motor vehicle or the autonomous driving motor vehicle.