Patent ID: 7690477
Filing Date: 2010-04-06
Classification: B62D

Abstract:
1. A vehicular steering system having a steering mechanism which includes a steering wheel installed on a vehicle and an electrically controlled auxiliary steering angle superposition mechanism for steering steerable road wheels of the vehicle, the system comprising: a steering wheel angle detection section that detects a steering angle of the steering wheel as a steering wheel angle; an auxiliary steering angle detection section that detects an auxiliary steering angle to be superposed by the auxiliary steering angle superposition mechanism; a steered angle detection section that detects a steered angle of the steerable road wheels as an absolute angle; a travel state detection section that detects the traveling state of the vehicle; a transmission characteristic setting section that sets a transmission characteristic between the steering wheel angle and the steered angle in accordance with the traveling state of the vehicle; a target auxiliary steering angle calculation section that calculates a target auxiliary steering angle to be superposed by the auxiliary steering angle superposition mechanism based on the steering wheel angle and the transmission characteristic; a driving control section that controls driving of the auxiliary steering angle superposition mechanism so as to make the auxiliary steering angle coincide with the target auxiliary steering angle; and an activation angle setting section that sets an initial value of the steering wheel angle detected by the steering wheel angle detection section as an activation steering wheel angle based on the steered angle and the transmission characteristic at the start of control of the auxiliary steering angle superposition mechanism, and also sets an initial value of the auxiliary steering angle detected by the auxiliary steering angle detection section as an activation auxiliary steering angle.