Nsk Corporation

Satoshi Shimokawabe

Takahiro Tsubaki

Tetsuya Kitazume

Toru Sakaguchi

Toshikazu Onoe

The present invention is the electric power steering apparatus that drives a motor based on the current command value and assist-controls a steering system by a driving-control of the motor, comprising: a handle-returning control section to calculate the target steering angle velocity for handle-returning based on the steering torque, the current command value, a vehicle speed, a steering angle, calculate the handle-returning control current based on a deviation between the steering angle velocity and the target steering angle velocity, and interpose a filter, which motion characteristic, in a calculation path of the target steering angle velocity, wherein the motor is driven by the corrected current command value by using the handle-returning control current.

Electric power steering apparatus

An electric power steering apparatus that drives a motor based a current command value and assist-controls a steering system by a driving-control of the motor. The apparatus includes a handle-returning control section that calculates a target steering angular velocity by using a steering angle, the vehicle speed, the steering torque and the current command value, calculates a handle-returning control current by using a limit-target steering angular velocity which is obtained by limiting the target steering angular velocity depending on steering angular velocity, and drives the motor by a compensated current command value which is obtained by adding the handle-returning control current to the current command value.

An electric power steering apparatus that includes a function to perform a handle-returning control being consistent with an intention of a driver by using, for a calculation of a target steering angular velocity, only a steering input due to the intention of the driver which is included in a steering torque and the assist current or only vehicle motion characteristics based on the steering input, in the handle-returning control which performs a PID-control depending on a deviation between the target steering angular velocity and a steering angular velocity.

[Problem] An object of the present invention is to provide an electric power steering apparatus that constitutes a control system based on a physical model, constitutes a model following control that an output (a distance to a rack end) of a controlled object follows-up to a reference model, suppresses the occurrences of a noisy sound and a shock force at an end hitting without giving any uncomfortable steering feeling to a driver, and is capable of smoothly steering. [Means for solving the problem] In the electric power steering apparatus that calculates a first current command value based on at least a steering torque and performs an assist-control of a steering system by driving a motor based on the first current command value, the apparatus comprises a configuration of a model following control comprising a feed-back control section including a viscoelastic model as a reference model within a predetermined angle at front of a rack end, wherein the configuration of the model following control comprises a feed-back control section, and the model following control has a noise-reducing function to reduce a noise so as to suppress a rack end hitting.

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Maebashi, Japan

Satoshi Shimokawabe