Energy-Based Coupling Control for 5-DOF Marine Cranes with Fuzzy Observation and Adaptive Gravity Compensation

With the rapid development of offshore engineering, marine cranes are widely deployed in critical maritime operations, such as the precision installation of wind turbine blades. However, their highly coupled three-dimensional spatial dynamics, uncertain payload mass, and susceptibility to severe external sea wave disturbances pose significant challenges in achieving fast, accurate payload transportation and rapid anti-swing performance. To address these issues, this paper proposes a novel energy-based intelligent coupling control strategy utilizing fuzzy logic and adaptive gravity compensation for 5-DOF (5-Degrees of Freedom) marine cranes. Firstly, to handle the severe underactuation and facilitate natural energy dissipation, a novel set of error coupling variables is constructed, organically linking the actuated crane structure with the unactuated payload swing dynamics. Then, an adaptive gravity compensation mechanism is designed to dynamically estimate the uncertain payload mass in real time, eliminating the need for precise prior mathematical models. Subsequently, to counteract complex external environmental disturbances and unmodeled internal dynamics, a targeted fuzzy observer is developed based on the universal approximation theorem, providing robust, real-time perturbation compensation. The sufficient conditions for the asymptotic stability of the closed-loop system are rigorously proven based on the Lyapunov method and LaSalle’s invariance principle. Finally, extensive comparative simulations are conducted, demonstrating that the proposed method significantly improves the operational accuracy, anti-swing capability, and safety of marine cranes under varying load conditions and persistent wave disturbances.