Research on dual coupling model for dynamic analysis of USV-assisted floating pipe docking for TSHDs

Pump-ashore floating pipe docking relies on manual connection for trailing suction hopper dredgers (TSHDs), leading to efficiency and safety bottlenecks. A docking solution involving a cabled unmanned surface vehicle (Cabled-USV) is proposed to address the complexities associated with multibody interactions and nonlinear disturbances. First, a TSHD hanging point model is established considering environmental loads and TSHD responses. Second, a dynamics model of the Cabled-USV is developed using a segmented lumped-mass method to capture the effects of variable cable constraints. Third, these sub-models are integrated to form a dual multibody framework with unidirectional constraint coupling from the TSHD to the Cabled-USV by a collaborative tracking strategy. A PID-based tracking strategy is employed to compensate for time-varying cable tension and variable stiffness constraints, ensuring precise trajectory tracking under different sea conditions. The USV seakeeping performance was examined through model tests. Simulation results for Sea States 1 and 2 indicated that the system achieved real-time tracking, with average deviations of 0.154 and 0.695 m, respectively. The robustness of the model and control strategy was further validated using real sea data (Sea State 2), yielding an average tracking error of 0.775 m, despite irregular acceleration disturbances. Finally, through inverse statistical analysis of the thrust demands, minimum power configuration criteria were established for USV operation.