Risk-Free Formation Reconfiguration Guidance for Unmanned Surface Vehicles Based on Polar-Coordinate Vector Fields

This paper investigates the formation reconfiguration of multiple underactuated unmanned surface vehicles (USVs) navigating a complex marine environment with multiple static obstacles. A formation reconfiguration guidance method is proposed for multiple USVs such that a collision-free behavior is achieved during the transformation of formation patterns. First, a polar-coordinate vector field (PCVF) method is implemented to generate local parameterized guidance vector fields around the static and dynamic obstacles. Next, a hybrid PCVFs is obtained by mixing all PCVFs based on a weight-based fusion method. Then, the orientation of the hybrid PCVFs is integrated with the desired formation reconfiguration heading through a moving weight average method. Finally, a saturated formation reconfiguration guidance method is proposed to depict the resultant speed and the yaw rate signals to track the desired composite heading signal, resulting in a collision-free formation reconfiguration behavior. It is proven that the closed-loop formation reconfiguration guidance system is input-to-state stable. Simulation results are provided to demonstrate the proposed risk-free formation reconfiguration guidance method for USVs.