Formation control of multiple marine vehicles with velocity reference estimation-based passivity-control design

This paper addresses the problem of coordination path following control of multiple autonomous vehicles. Stated briefly, the problem consists of steering a group of vehicles along a specified path, while holding a desired inter-ship formation pattern. Path following for each vehicle amounts to reducing an appropriately defined geometric error to zero. We first show a passivity property for the path following system and, next, combine this with a passivity-based synchronisation algorithm to coordinate the vehicles along their paths. Vehicle coordination is achieved by adjusting the speed of each vehicle along its path according to information exchanged on the positions of a subset of the other vehicles, as determined by the communication topology adopted. We further assume the unavailability of the reference velocity to each vehicle; we consider the situation where this information is only available to a leader of this formation. Distributed observers are designed for the follower vehicles, under the assumption that the velocity of the leader cannot be measured in real time. Simulations results are presented and discussed.