Coordinated path-following control of multiple autonomous underwater vehicles

The concept of multiple Autonomous Underwater Vehicles (AUVs) cooperatively performing a mission offers several advantages over single vehicles working in a non-cooperative manner such as increased efficiency, performance, reconfigurability, robustness and the emergence of new capabilities. This paper introduces the concept of coordinated path-following control of multiple AUVs. The vehicles are required to follow pre-specified spatial paths while keeping a desired inter-vehicle formation pattern in time. We show how Lyapunovbased techniques and graph theory can be brought together to yield a decentralized control structure where the dynamics of the cooperating vehicles and the constraints imposed by the topology of the intervehicle communications network are explicitly taken into account. Path-following for each vehicle amounts to reducing an appropriately defined geometric error to a small neighborhood of the origin. Vehicle coordination is achieved by adjusting the speed command of each vehicle along its path according to information on the positions of a subset of the other vehicles, as determined by the communications topology adopted. We illustrate our design procedure for underwater vehicles moving in three-dimensional space. Simulations results are presented and discussed.