Coordinated Path Following for Multiple Underactuated Surface Vehicles with Error Constraints

In this paper, the coordinated path following control of multiple underactuated surface vehicles with error constraints is studied. By combining tan-type barrier Lyapunov functions, a novel coordinated guidance law composed by desired surge speed and heading angle for each vehicle is proposed. The coordination task is completed by assigning the same number of parametric paths to vehicles, introducing coordination error variables based on graph theory, and then the desired update law for each parameter of path is proposed. In order to quickly and accurately track the desired guidance signal with high robustness, a neural network controller was designed for each unmanned vehicle using backstepping method, in which the neural network is used to quickly estimate unknown dynamic disturbances. All closed-loop tracking errors are proved to be uniform ultimately bounded by Lyapunov theory. In addition, the coordinated path following errors are bounded in the prescribed boundaries.