Patent ID: 7349781
Filing Date: 2008-03-25
Classification: B62D

Abstract:
1. An electric power steering apparatus for a vehicle comprising: a motor for generating steering assist power; a torque determination part for determining steering torque; a storing part for storing a relationship between the steering torque and basic assist torque, in which the relationship is stored as assist characteristic; a steering angle correspondence value determination part for determining steering angle correspondence value corresponding to steering angle of the vehicle; a storing part for storing a relationship between the steering angle correspondence value and motor output correction value, in which the relationship is stored as correction characteristic; and a correcting part for correcting the output of the motor, which is required in order to generate the basic assist torque, in accordance with the motor output correction value determined on the basis of the determined steering angle correspondence value and said correction characteristic, in which the basic assist torque is determined on the basis of the determined steering torque and said assist characteristic; wherein said correction characteristic is set so that the denominator in the frequency transfer function of the motor output correction value to the steering angle correspondence value has a term which includes the resonance angular frequency of the yaw motion of the vehicle, and a term which includes the damping ratio of the yaw motion of the vehicle.