Electric power steering apparatus

Abstract

The invention provides electric power steering apparatus includes an operation amount detecting unit for detecting an operation amount of an operation member for steering a motor vehicle; a reference assist characteristics setting unit for setting reference assist characteristics which are reference characteristics of a motor driving target value corresponding to the operation amount of the operation member; a motor driving target value setting unit for setting a motor driving target value in accordance with corrected assist characteristics obtained by shifting the reference assist characteristics along an axis of coordinates of the operation amount; a yaw rate detecting unit for detecting or estimating a yaw rate of the motor vehicle; and a shifting amount setting unit for setting a shifting amount of the corrected assist characteristics with respect to the reference assist characteristics corresponding to the yaw rate of the motor vehicle.

Description

technical field [0001] The present invention relates to an electric power steering device having a structure in which a driving force generated by an electric motor is transmitted to a steering mechanism as a steering assist force. Background technique [0002] There has been conventionally used an electric power steering apparatus having a structure in which a driving force generated by an electric motor is mechanically transmitted to a steering mechanism through a gear mechanism (reduction mechanism) or a direct transmission system, thereby assisting steering. [0003] In such an electric power steering apparatus, an assist characteristic determining the steering torque applied to the steering wheel and the steering torque applied to the steering mechanism from the electric motor is predetermined and stored in the memory as an assist map. Relationship between assist torque target values. Then, an assist torque target value corresponding to the steering torque is read from...

AI Technical Summary

Problems solved by technology

[0006] In an electric power steering system to which such an assist characteristic is applied, there is a problem in that, when the return steering is performed to rotate the steering wheel toward the midpoint of the steering angle, the steering angle toward the midpoint of the steering angle is stronger than the driver's expectation. Returned steering feel (so-called spring feel)

However, in the above-mentioned prior art, since the assist amount is increased, it may be felt that the feel at the time of cutting is impaired immediately after the steering speed becomes zero.

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