Enhancement of lateral stability of car-trailer systems using model-reference adaptive control

Abstract

Car-Trailer (CT) systems exhibit reduced maneuverability in curved-path negotiations and display low lateral stability under high-speed evasive maneuvers. Therefore, the objective of this thesis is to design a Lyapunov-Stability-based Model Reference Adaptive Controller (MRAC) for an active trailer steering system to enhance the lateral stability of CT systems considering parametric uncertainties and unknown dynamics of the actuator. To this end, a reference model is designed using a 3-DOF (degrees of freedom) linear CT model with active trailer steering; the virtual vehicle, i.e., the nonlinear CT model with 22-DOF, is developed in CarSim software; the MRAC controller is constructed in Simulink/MATLAB. To explore the robustness of the Lyapunov-Stability-based MRAC controller with respect to uncertainties, co-simulations are carried out by integrating the virtual CT developed in CarSim, the reference model and MRAC controller designed in Simulink/MATLAB. Simulations reveal that the proposed controller adapts to external disturbances and parametric variations very well. Specifically, the research leads to the insightful finding that the adaptive controller based active trailer steering system can effectively improve the lateral stability of CT systems, and the proposed design methodology will provide a valuable guideline for the development of advanced active safety systems for CT systems in the future.