NONLINEAR MOTION CONTROL OF MULTIPLE AUTONOMOUS UNDERWATER VEHICLES

This paper addresses the problem of steering a group of underactuated Autonomous Underwater Vehicles (AUVs) along given spatial paths, while holding a desired inter-vehicle formation pattern (coordinated path-following, abbreviated CPF). Exploiting Lyapunov-based techniques and graph theory, a decentralized control law is derived that takes into account the dynamics of the cooperating vehicles, the constraints imposed by the topology of the inter-vehicle communications network, and the cost of exchanging information. The CPF problem is divided into the motion control task of making each vehicle track a virtual target moving along the desired path, and the dynamic assignment task of adjusting the speeds of the virtual targets so as to achieve vehicle coordination. At the path-following level, the controller derived exhibits an inner-outer loop structure. Convergence and stability of the overall system are proved formally. Simulations results are presented and discussed.