Prescribed-time safe fencing control of multiple unmanned surface vehicles with multiple obstacle constraints

This paper addresses the safe fencing control issue of multiple unmanned surface vehicles (USVs) with multiple obstacle constraints. A prescribed-time distributed safe fencing hierarchical control method is proposed. In the guidance layer, a distributed asymptotic average fencing guidance method is employed to ensure that the formation converges around the target with uniformly distributed relative angles within a prescribed-time. When the formation encounters multiple obstacles, a smooth control barrier function (CBF) based on Boolean logic is utilized to approximate the multiple obstacle constraints. Furthermore, a Quadratic Programming problem is established based on the smooth CBF to optimize the velocity commands from the guidance layer, generating safe velocity commands in real-time to ensure safe distances among USVs and between USVs and multiple obstacles. In the control layer, a prescribed-time adaptive sliding mode control method is designed to ensure accurate tracking of the safe velocity commands. The theoretical validity of the proposed method is proved through Lyapunov analysis. Numerical simulations further validate both the efficacy and advantages of the proposed control strategy.