Patent ID: 6729435
Filing Date: 2004-05-04
Classification: B62D

Abstract:
An apparatus for controlling an electric power steering system located between a steering wheel and a steered vehicle wheel, wherein the electric power steering system includes a motor, and wherein the motor generates assist force for reducing steering force of the steering wheel and compensation force for compensating for movement of the steering wheel, the apparatus comprising:first calculation means for calculating an assist current command value that corresponds to the assist force based on the steering torque of the steering wheel; second calculation means, wherein the second calculation means estimates the angular velocity of the steering wheel based on a terminal-to-terminal voltage of the motor and calculates a compensation current command value that corresponds to the compensation force based on the estimated steering wheel angular velocity; control means for controlling the motor based on the sum of the assist current command value and the compensation current command value; and detection means for detecting an abnormality of a terminal voltage of the motor, wherein, when an abnormality of the terminal voltage is detected, the second calculation means substitutes a predetermined fixed value for the steering wheel angular velocity and then calculates the compensation current command value.