Target Circumnavigation Control with an Unmanned Surface Vehicle based on Relative Range Measurements

This paper considers the problem of uncooperative target circumnavigation with an unmanned surface vehicle (USV) in the marine environment. The vehicle is driven to circumnavigate the target with the desired radius. A coordinate-free controller with a designed saturation function is proposed using only the local relative range information. The stability of the proposed algorithm is theoretically guaranteed by Lyapunov control theory. Moreover, a second-order sliding mode (SOSM) observer combined with linear and nonlinear terms is designed to estimate the range rate with respect to the target. The global stability and convergence are also proved using the Lyapunov theory. Finally, numerical simulations and real experiments with a USV are carried out to show the effectiveness of proposed approach. The results show that the steady-state circumnavigation error converges to zero and the SOSM observer can recover the real range rate within finite time.