Electric power steering system and method having abnormality compensation function

Abstract

A vehicle electric power steering system comprises a torque sensor including a torsion bar that detects a steering force applied to the steering wheel. A first rotation angle detection device detects a rotation angle of a steering shaft connected to the torsion bar, and a second rotation angle detection device detects a rotation angle of a pinion shaft connected to the torsion bar. A steering controller detects an abnormality in an output of the torque sensor. The steering controller detects the steering torque in place of the torque sensor based on the rotation angle of the steering shaft and the pinion shaft when an abnormality of the torque sensor is detected.

Description

technical field [0001] The present invention relates to an electric steering system and method; more particularly, the present invention relates to a torque sensor fault compensation for an electric steering system based on an estimated twist angle of the torque sensor. Background technique [0002] In an electric power steering system for assisting a driver's wheel steering operation, when an abnormality of a torque sensor is detected, the assist is cut off by a fail-safe device. That is, immediately after the abnormality is detected, the current applied to the assist motor is reduced to zero. As a result, the steering wheel's operating force can suddenly become very high due to the loss of power assist produced by the electric motor. [0003] Compensate for these situations by testing alternative torque sensors used to control the steering wheels, or by stopping power assist etc. as a fail-safe operation. However, this substitution torque sensor reduces the mountability ...

AI Technical Summary

Problems solved by technology

[0005] In the above documents, the first and second documents have problems with the accuracy of the steering torque caused by the location of the steering angle sensor at the steering wheel end, or the pinion end of the torsion bar connected to the steering shaft

Moreover, the second document forces the driver to finally apply steering effort (without assist) to increase

In addition to the lack of power, the third document has the same accuracy problems as the first and second documents

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