Fixed-Time Backstepping Tracking Control for 5-DOF Marine Cranes With Error Constraints and Unavailable Velocity Information

With the development of Marine technology, Marine cranes have been widely deployed in various maritime operations. However, their complex model parameters, external disturbances, and underactuated characteristics pose significant challenges to achieving fast and accurate payload transportation with rapid anti-swing performance. This article proposes a fixed-time trajectory tracking control with error constraints for degrees of freedom 5-DOF Marine cranes. First, to handle unavailable velocity information and unknown model parameters, a fixed-time extended state observer (FTESO) and a fixed-time differentiator are designed. Then, to enhance tracking performance, a preset performance error constraint signal is designed. Subsequently, by integrating error constraints, preset trajectories, and fixed-time theory, a fixed-time tracking controller is designed via backstepping method. Furthermore, sufficient conditions for uniformly globally fixed-time stability are established based on Lyapunov theory. Finally, simulation experiments are conducted on the proposed controller, and comparative tests and robustness tests are carried out on the hardware experimental platform. Experimental results demonstrate that the proposed method significantly improves the operational accuracy and safety of Marine cranes.