Robust Safety-Preserving Rendezvous Control for Coordinated Heterogeneous Marine Vehicles: An Observer-Based Structure-Keeping Port-Hamiltonian Approach.

This article studies the 3-D dynamic rendezvous control problem for coordinated heterogeneous marine vehicles, including an uncrewed underwater vehicle (UUV) and an autonomous surface vehicle (ASV). An observer-based safety-preserving rendezvous control approach is proposed to robustly stabilize the rendezvous errors under the port-Hamiltonian (PH) framework. First, an interconnection and damping assignment passivity-based control (IDA-PBC) method is adopted to provide a basic stabilizing control framework. In this problem, both vehicles are faced with hydrodynamic model uncertainties and unknown external disturbances. Then, to preserve the rendezvous safety under uncertain dynamics, the prescribed performance control (PPC) transformation is implemented for the ascending motion to get the equivalent approaching-constrained PH system. The intuitive design procedure provided by the IDA-PBC method, along with the collision-free rendezvous safety guaranteed by the auxiliary PPC technique, reduces the controller design complexity while providing a smooth rendezvous trajectory. Besides, a structure-keeping uncertainty observer algorithm is designed and incorporated to simultaneously handle model uncertainties and environmental disturbances without destroying the interconnection structure. Under the proposed approach, the UUV-ASV rendezvous errors can be effectively stabilized with rigorous closed-loop stability analysis. Finally, both simulations and comparative experiments are conducted to demonstrate the effectiveness and advantages of the proposed approach.