Adaptive target tracking for 6-degrees underactuated vehicle

This paper deals with a control strategy for underactuated underwater vehicle moving in 6-degrees of freedom whose target is the tracking of a space trajectory. The control algorithms proposed build upon Lyapunov's method and backstepping technique, which force the vehicle follow any smooth time-varying bounded trajectory, despite of the uncertainty in the damping coefficient and absence of the force of sway and heavy. The error of tracking and parameter estimation are ultimately confined to a ball that can be made arbitrarily small.