Steering control for lateral stability and maneuverability of tug-aircraft system on motion deck

A tug-aircraft combination working on a warship is a special class of articulation system. The mobility of such a nonlinear system is subjected to the hinge joint and aircraft giant shape, especially the uncertain warship movements which generate time-varying contact forces on the system. It leads to many challenges in control strategies. Herein, a back stepping sliding mode variable structure controller is developed to increase the lateral performance and maneuverability of a tug-aircraft combination on deck (TACD) using active tug four-wheels steering. Firstly, a nonlinear and time-varying dynamic model of TACD is constructed, which couples the warship motions. A control strategy is then proposed, in which the steering of the rear wheel of the tug is defined as the input, and additional dynamic compensatory steering of the front wheel is introduced to improve maneuverability. A constructive back-stepping sliding mode variable structure controller has been implemented on the augmented system model, which introduces the second-order models of the steering assembly. The simulation results confirm the effectiveness and robustness of the proposed control algorithm.