This dissertation describes the robust controller design methods applied to the problem of an automatic steering system for tow-vehicle/trailer combinations. This study followed an Inverse Linear Quadratic Regulator (ILQR) approach and combined pole assignment methods with conventional Linear Quadratic Regulator (LQR) methods. It overcomes two concerns associated with these separate methods: the robustness problems associated with pole placement methods and the trial and error required in the application of the LQR method. The combination of the robust regulator and robust filter is called a ILQR/LTR controller.; The proposed ILQR/LTR controller enhances the forward motion stability and maneuverability of the combination vehicles at high speeds. Furthermore, when combined with ILQG/LTR, the new method, called Parameter Robustness Control, is applied to forward motion control. In addition, for improvement of the backward motion control a multiwheel control method with four-wheel steering (4WS) tow-vehicle is proposed by using ILQG/LTR method. This method reduces off-tracking and improves the protection against jackknifing with sufficient parameter robustness.; To evaluate the stability and robustness of the controllers, simulations were conducted using a detailed nonlinear model. All the proposed controllers are significantly more robust than the previous controllers and continue to operate effectively in spite of parameter perturbations that would cause previous controllers to enter limit cycles or to lose stability. In addition, implementation issues, including the digital redesign, required sensors, and reconfiguration procedures for failure recovery are presented.
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