Distributed Control of Unmanned Marine Vehicles for Target Circumnavigation in Communication-Denied Environments

This article considers the problem of target circumnavigation using multiple unmanned marine vehicles in the communication-denied environment. The vehicles are required to circumnavigate the target maintaining a desired radius and evenly spaced positions relying solely on local relative range measurements. A novel distributed control strategy with a saturation function design is proposed for cooperatively circumnavigating both static and dynamic targets. Via the Lyapunov control theory and the input-to-state property, the closed-loop stability with only the relative range information is achieved. The steady-state circumnavigation error converges to zero and is uniformly ultimately bounded for the static and dynamic targets, respectively. In addition, a second-order sliding mode observer is developed to estimate the range rate information. The observer incorporates linear and nonlinear correction terms and is proven to be global asymptotically stable. The finite time convergence property also contributes to the control performance. Finally, numerical simulations and real experiments involving three unmanned surface vehicles are conducted. Compared with the existing approach, the proposed method shows convenience in implementations and better circumnavigation control performance especially for dynamic targets.