Fault tolerant finite-time leader follower formation control for autonomous surface vessels with LOS range and angle constraints

In this work, we present a novel fault tolerant leader-follower formation control scheme for a group of underactuated autonomous surface vessels with partially known control input gain functions, where the line-of-sight (LOS) range and angle tracking errors are required to be constrained. Both parametric system uncertainties with time-varying unknown functions and nonparametric system uncertainties satisfying norm-bounded conditions are discussed. To address LOS range and angle constraints and finite time convergence, time-varying tan-type barrier Lyapunov functions (BLFs) are incorporated with the control scheme. For the formation control, only measurements of LOS range and angle are used for control implementation, no other information about the leader is required. We show that under the proposed control method, despite the presence of actuator faults and system uncertainties, the formation tracking errors can converge into arbitrarily small neighborhoods around zero in finite time, while the constraint requirements on the LOS range and angle will not be violated. All closed loop signals are bounded. Simulation results further demonstrate the effectiveness of the proposed method. (C) 2016 Elsevier Ltd. All rights reserved.