Synchronization control of multiple surface vessels without velocity measurements

In this paper, we study the position synchronization problem of multiple surface vessels with model uncertainties and external disturbances. The synchronization controller is proposed under the situation when velocity measurements are unavailable. Extended state observer is employed to estimate the velocity measurements and the unknown external disturbances. Coupling errors are introduced to design the feedback control laws. It is shown that with the developed cooperative scheme, position synchronization can be achieved under an undirected connected communication graph. Based on the Lyapunov stability analysis, all the closed-loop signals are guaranteed to be uniformly ultimately bounded. Simulation results are given to demonstrate the effectiveness of the proposed methods.