A Robust Backward Steering Controller Design for Combination Vehicles

This paper considers robust controller design applied to a backward steering system for tow-vehicle/trailer combinations. An Inverse Linear Quadratic Regulator (ILQR) approach is followed. It combines pole assignment methods with conventional LQ problem. It overcomes two problems associated with these separate methods. It overcomes the robustness problems of pole placement methods, and overcomes the trial and error required in the LQR method. A Kalman observer is used, but is modified by using the loop transfer recovery (LTR) technique. The combination of the robust LQ problem and robust filter is called a ILQG/LTR controller.

The proposed controller is applied to both 2WS and 4WS tow-vehicle and shows significantly more robust performance than previous controllers. Moreover, employing a 4WS tow-vehicle significantly expands the range and effectiveness of the control.