Active Tracking Control for Steer-by-Wire System With Disturbance Observer

Abstract

The operation of the steer-by-wire (SBW) system without physical transmission mechanism is relied on the control of steering actuation. The main disturbance during the tracking control of steering actuation is the nonlinear rack force caused by the vehicle tire-road interaction. To improve the steering performance of SBW system, a steering controller with an active rack force compensation concept is proposed in this paper for the tracking control algorithm design. Three kinds of disturbance observers are established to show the efficiency of rack force estimation during the steering control. By utilizing an extended disturbance observer into a robust sliding mode control, an active tracking controller with feedforward compensation is designed for the SBW system. The proposed algorithms are validated with different driving test cycles from ISO standards in software-in-loop and hardware-in-loop experiments. The results have shown the effectiveness of the rack force estimation and tracking performance by the proposed controller, even in the extreme testing conditions.