Phase plane based transitional damping for electric power steering

Abstract

A method for controlling a motor in an electrical power steering system is provided. The method generates a damping torque command for reducing an undesired torque to be generated by the motor. The method generates an assist torque command that specifies a desired torque to be generated by the motor. The method determines whether to send the damping torque command to the motor as a function of a hand wheel velocity and a hand wheel angle. The method combines the assist torque command and the damping torque command to send to the motor when it is determined that the damping torque command is to be sent to the motor.

Description

Background technique [0001] In a typical vehicle electric power steering (EPS) system, a steering wheel torque sensor is used to determine the driver's requested assist torque. When the steering wheel torque sensor becomes malfunctioning and does not function properly, the EPS system may not be able to provide assist torque. In some situations, the vehicle also enters a limp mode, where the vehicle operates in a restricted manner, where the steering wheel torque sensor performance degrades. Accordingly, it would be desirable to have an EPS system that better handles steering wheel torque sensor degradation. [0002] In an electric power steering (EPS) system, the assist torque provided by the electric machine typically reduces the steering effort applied by the driver. In certain situations, such as when the performance of the torque sensor used to determine the driver's required assist torque drops, the assist torque is cut off immediately. When the EPS system ceases to pr...

AI Technical Summary

Problems solved by technology

When the EPS system ceases to provide assist torque, a sudden perceptible change in steering wheel torque felt by the driver may occur

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