Electric power steering system

Abstract

An electric power steering system determines a steering state of a steering wheel on the basis of a current (Im) of a motor applying assist force to a steering system and a steering speed (ωs) of the steering wheel. A state where the steering wheel is retained at a position other than a neutral position is a retained state, and a state where the steering wheel is placed at the neutral position is a neutral state. When the steering speed (ωs) is lower than a determination value (ωa) and the motor current (Im) is larger than a reference value (Ix), it is determined whether the steering state is the neutral state. When the steering speed (ωs) is lower than the determination value (ωa), the motor current (Im) is larger than the reference value (Ix), and the steering state is determined to be the neutral state at immediately preceding determination, the steering state is determined to be the neutral state.

Dependencies are inferred from the claim text.