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This paper presents an optimal control strategy for assigning wheel slips on all of the wheels of a tractor/trailer combination. Most ABS controllers work on a wheel by wheel or an axle by axle basis without consideration for overall system stability. This controller is based on a linear program (LP) and assigns wheel slips for each wheel in accordance with one of the following criteria: 1) During an emergency braking maneuver, optimal wheel slips are determined which maximize stopping while constraining the system to be stable, or 2) During a nonemergency braking maneuver, the controller is used to maximize stability while maintaining an achievable (commanded) deceleration. Computer simulations, which modeled a full tanker truck, were run to compare the response of the proposed controller with two controllers which incorporated select-low control and individual control ABS systems on various axles.

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.