Nsk Corporation

Masahiro Ieyasu

Masahiro Maeda

[Problem] An object of the present invention is to provide a high-performance electric power steering apparatus that reduces uncomfortable feeling of a driver by improving judgment of turning or returning and performing fine control of a steering state to improve a function of convergence control. [Means for solving the problem] An electric power steering apparatus comprises: a turning or returning state index calculating section that calculates a turning or returning state index based on a steering torque and a motor angle velocity; a turning or returning state ratio calculating section that calculates a turning or returning state ratio with a nominal value as a reference based on the turning or returning state index; and a convergence control section that comprises a sensitive gain section that calculates a turning gain and a returning gain based on the steering torque, a vehicle speed and the motor angle velocity, a gain correcting section that performs gain correction for the turning gain and the returning gain by the turning or returning state ratio, and an output processing section that outputs a convergence control value by performing output processing of a gain signal from the gain correcting section based on an absolute value and a sign inversion signal of a yaw rate estimation value.

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Maebashi, Japan

Masahiro Ieyasu