Patent ID: 7918306
Filing Date: 2011-04-05
Classification: B62D

Abstract:
1. An electric power steering apparatus, comprising: a motor for generating steering assist power; a torque sensor for detecting steering torque; a storage element for storing a corresponding relationship between the steering torque and a target output value of said motor; a calculation element for calculating the target output value with the detected steering torque and the corresponding relationship; a detection element for detecting an actual output value of said motor; an output control element for controlling output of said motor according to an output command value corresponding to a deviation between said target output value and said actual output value so as to eliminate said deviation; a phase control element for controlling a phase of a signal corresponding to the detected steering torque; and a steering state judgment element for judging whether a steering wheel is in a return steering state in which the steering wheel is steered toward the straight traveling steering position or a feed steering state in which the steering wheel is steered away from the straight traveling steering position, wherein a phase control characteristic of said phase control element is changed according to the judgment by said steering state judgment element so that a response of a variation of said target output value to a variation of said detected steering torque in the return steering state decreases in comparison with that in the feed steering state, and an output control characteristic of said output control element is changed according to the judgment by said steering state judgment element synchronously with the change of the phase control characteristic of said phase control element so that a response of a variation of said output command value to a variation of the deviation between said target output value and said actual output value in the return steering state decreases in comparison with that in the feed steering state.