Model-Free Adaptive Integral Sliding Mode Control for 4-DOF Tower Crane Systems

An adaptive integral sliding mode control (AISMC) method with payload sway reduction is presented for 4-DOF tower cranes in this paper. The designed controller consists of three parts: the integral sliding mode control (ISMC) is used to provide the robust behavior; the adaptive control is utilized to present the adaptive performance; the swing-damping term is added to suppress and eliminate the payload swing angles. Different from existing sliding mode control (SMC) methods, the proposed AISMC method doesn't include the switching action, therefore, it is continuous and chattering free. Moreover, a prior knowledge of the system parameters including the payload mass, the trolley mass, the cable length, the moment of inertia of the jib, the friction-related coefficients is not required for the designed controller thanks to the adaptive control. Lyapunov-based analysis and LaSalle's invariance principle are employed to support the theoretical derivations without linearizing the nonlinear dynamics. Experimental results are illustrated to show the superior control performance of the designed controller.