Continuous integral-type sliding mode tracking control of under-actuated cranes: theory and experiments

Abstract

We propose continuous integral-type sliding mode tracking control (CIT-SMTC) for a class of under-actuated gantry/bridge cranes. Compared to the available sliding-mode-based approaches for crane systems, the notable improvements of the proposed CIT-SMTC include: (i) the assurance of the soft start through the trajectory tracking control mode; (ii) the enhancement of system performance in terms of convergence time and control accuracy; (iii) the continuity of the control action; and (iv) the complete stability analysis of the overall closed-loop system. In the proposed control structure, an integral-type sliding surface is first designed such that during the sliding phase, the stability of the closed-loop system is guaranteed and the control performance of crane systems is enhanced. Then, by employing the introduced integral manifold and the super-twisting-like algorithm, the CIT-SMTC is proposed such that the states are restricted to the sliding surface in finite time and the continuous control signal is imposed. Rigorous analysis is provided to prove the stability of the overall closed-loop system. Finally, experimental results are shown to verify the superiority of the proposed CIT-SMTC.