Nonlinear formation control of marine craft with experimental results

Decentralized formation control schemes for a fleet of vessels with a small amount of intervessel communication are proposed and investigated. The control objective for each vessel is to maintain its position in the formation relative to a formation reference point, which follows a predefined path. This is done by constructing an individual parametrized path for each vessel so that when the parametrization variables are synchronized, the vessels are in formation. To obtain this, an individual maneuvering problem is solved for each vessel, with an extension of a synchronization feedback function in the dynamic control laws to ensure that the vessels stay assembled in the desired formation. This setup assures that all vessels will have the same priority, i.e. no leader. Performance and theoretical results are validated by experiments for a scaled model ship and a computer simulated ship in a marine control laboratory.