Friction estimation and detection for an electric power steering system

摘要

A method of estimating friction in a steering system controlled by a control module is provided. The method includes performing by the control module, estimating a steering load gain; estimating a steering load hysteresis; and determining friction based on the steering load gain, the steering load hysteresis, and a reference model.

主权项

1. A method of estimating friction in a steering system controlled by a control module, comprising:
performing by the control module,
computing lateral acceleration based on steering angle and vehicle speed;estimating a steering load gain by determining a difference between a steering load and an average hysteresis value, and dividing the difference by the lateral acceleration;estimating a steering load hysteresis comprising: a first hysteresis value based on the lateral acceleration increasing as the steering load minus the steering load gain multiplied by the lateral acceleration, and a second hysteresis value based on the lateral acceleration decreasing as the steering load minus the steering load gain multiplied by the lateral acceleration, the average hysteresis value being an average of time delayed values of the first and second hysteresis values;determining friction in the steering system based on the steering load gain, the steering load hysteresis, and a reference model; andinitiating a warning signal when the friction in the steering system exceeds at least one threshold.