Fixed time trajectory tracking control for Marine crane with anti-saturation input and unmatched disturbances

Even through the Marine crane have been widely used in maritime logistics, port construction, and military sectors, the precise tracking control should address a lot of challenges, such as the complex external disturbances, the input saturation characteristics and the unknown/unmatched disturbances et al. Therefore, a preset-performance fixed-time control method is proposed considering the anti-saturation input and unmatched disturbances. Firstly, in order to precisely estimate and compensate the unmatched disturbances, a novel fixed time disturbances observer is designed in detail. Then, a fixed time adaptive trajectory tracking controller is designed step-by-step way, by integrating the preset trajectories, the disturbances observer, and the dynamic sliding mode. And, the convergence and stability of the system are analyzed, and the sufficient conditions for uniformly globally fixed-time stability are given based on Lyapunov theory. Finally, both the simulations and hardware experimental are conducted with comparative methods. The experimental results demonstrate that the proposed method substantially enhances operational accuracy and safety in Marine cranes.