Path following for multiple underactuated Autonomous Underwater Vehicles with formation constraints

This paper addresses the problem of steering a group of underactuated Autonomous Underwater Vehicles along specified paths while keeping a desired spatial formation. The controller proposed consists of a nonlinear path following control law and a coordination control law. The new type of path following control law takes an arbitrary variable but not necessarily the curvilinear abscissas variable to describe the referenced path, by which the stringent initial condition constrains existed in current path following controllers are extended; The coordination control strategy proposed only need the vehicles communicate the information of the coordinated variable, so the information flow is small and satisfies with a practical standpoint. For the overall closed-loop system, it is shown in detail how Lyapunov-based techniques and graph theory can be brought together to design a decentralized control structure, where the vehicle dynamics and the constraints imposed by the topology of the inter-vehicle communication network are explicitly taken into account.