Prescribed-time formation control of surface vessels with asymmetric constraints on LOS range and bearing angles

This paper investigates a prescribed-time formation control problem for a group of underactuated surface vessels (USVs) with asymmetric constraints on the line-of-sight range and bearing angle tracking errors. To cope with the time-varying constraints, we present a control method based on asymmetric barrier Lyapunov functions. A scaling function is introduced in the control law with which the settling time can be prescribed in advance as needed. The controllers are developed under the backstepping method framework, with the environmental disturbance being estimated by a novel prescribed-time observer, to ensure the global prescribed-time convergence of the USV formation. We prove that under the proposed control method, despite the interference of environmental disturbance, the formation tracking errors can converge to zero in the prescribed time without violating the constraints on the tracking errors. Simulation results further illustrate the effectiveness of the method proposed in this paper.