Nonlinear Formation Control of a Group of Underactuated Ships

This paper addresses a nonlinear formation control of a group of underactuated ship at a dynamic level of planar formation control, while holding a desired inter-ship formation pattern. In particular we propose a combination of the virtual structure and the path following approaches to derive the formation architecture. Ship coordination is achieved by adjusting the speed of each of the ships along its path, in the sense that the derivative of the path is left as a free input to synchronize the ships motion. The proposed controller is basically based on Lyapunov direct method and backstepping technique. Simulations illustrate the efficacy of the proposed approach.