Patent ID: 7155327
Filing Date: 2006-12-26
Classification: B62D

Abstract:
1. A control apparatus for an electric power steering system, which controls a motor for applying assist steering torque to a steering line of a vehicle at least according to steering torque signal of the steering line detected by a steering torque sensor, vehicle velocity signal detected by a vehicle velocity sensor and motor current signal detected by a motor current detector, the control apparatus comprising: a target current controller that receives the steering torque signal and is operational to set target current signal for driving the motor according to the steering torque signal; a deviation calculator that receives the target current and motor current signals and is operational to compute a deviation between the target current and motor current signals; an attenuator that receives the deviation and adjusts the deviation by an attenuator gain; the attenuator including a first determinator that determines a first gain based on the vehicle velocity signal, a second determinator that determines a second gain based on a differential of the steering torque signal, and an adder that computes the attenuator gain by adding the first and second gains; a proportional element operational to execute proportional control for the motor according to the adjusted deviation; and an integral element operational to execute integral control for the motor according to the adjusted deviation.