Vehicle steering device and control method for vehicle steering device

A controller for a vehicle steering device for a vehicle including a steering wheel operable by a driver and having a steering wheel shaft connected thereto, a turning mechanism operable to turn at least one steered wheel, a turning actuator operable to apply torque to the turning mechanism, a reaction force actuator connected to the steering wheel to apply a steering reaction force thereto, and a selectively engageable clutch positioned between the steering wheel and the turning mechanism and including a first rotary member mechanically connected to the turning mechanism, a second rotary member mechanically connected to the steering wheel shaft, and an engaging piece interposed between the first rotary member and the second rotary member, the clutch having an engaged position when the engaging piece is in wedging engagement between the first rotary member and the second rotary member wherein the steering wheel shaft is mechanically connected to the turning mechanism for turning the at least one steered wheel, and the clutch having a disengaged position when the engaging piece is in intermediate position between the first rotary member and the second rotary member wherein the steering wheel shaft is mechanically separated from the turning mechanism for steer-by-wire control of the at least one steered wheel, the controller comprising:

• means for controlling the turning actuator such that a turning angle of the at least one steered wheel corresponds to a steering angle of the steering wheel and for simultaneously controlling the reaction force actuator such that a steering reaction force is applied to the steering wheel;
• and
• means for reducing a relative angular acceleration between the steering wheel and the turning mechanism when the steering reaction force is higher than a prescribed steering reaction force by controlling at least one of the turning actuator and the reaction force actuator.

A control method of a vehicle steering device for a vehicle including a steering wheel operable by a driver and having a steering wheel shaft connected thereto, a turning mechanism operable to turn at least one steered wheel, a turning actuator operable to apply torque to the turning mechanism, a reaction force actuator connected to the steering wheel to apply a steering reaction force thereto, and a selectively engageable clutch positioned between the steering wheel and the turning mechanism and including a first rotary member mechanically connected to the turning mechanism, a second rotary member mechanically connected to the steering wheel shaft, and an engaging piece interposed between the first rotary member and the second rotary member, the clutch having an engaged position when the engaging piece is in wedging engagement between the first rotary member and the second rotary member wherein the steering wheel shaft is mechanically connected to the turning mechanism for turning the at least one steered wheel, and the clutch having a disengaged position when the engaging piece is in intermediate position between the first rotary member and the second rotary member wherein the steering wheel shaft is mechanically separated from the turning mechanism for steer-by-wire control of the at least one steered wheel, the method comprising:

• controlling the turning actuator such that a turning angle of the at least one steered wheel corresponds to a steering angle of the steering wheel and simultaneously controlling the reaction force actuator such that a steering reaction force is applied to the steering wheel;
• and
• reducing a relative angular acceleration between the steering wheel and the turning mechanism in response to detection of an operating condition by controlling at least one of the turning actuator and the reaction force actuator.