Coordinated trajectory tracking control for an underactuated tractor-trailer vehicle via MPC and SMC approaches

This paper presents a double closed-loop control strategy to achieve a coordinated path tracking control for an underactuated tractor-trailer vehicle, subject to the nonholonomic constraint, uncertain disturbance and various physical limits. The proposed double closed-loop control structure consists of a model predictive control (MPC) based posture controller and a sliding mode control (SMC) based dynamic controller on the outer and inner loops, respectively. The former MPC-based controller can make the midpoint of two parallel plating wheels for the underactuated trailer follow an arbitrary reference trajectory given by earth-fixed frame, as well as satisfying various physical limits. Meanwhile, the latter SMC-based controller will drive the vehicle velocities to track the desired velocities produced by the former one, and the global asymptotical convergence of inner closed-loop is strictly guaranteed in sense of stability theorem. The simulation results validate the proposed control strategy is rather effective and efficient in the case of the underactuated tractor-trailer vehicle, thereby demonstrating the effectiveness and feasibility of the designed controllers.