Further Results on Fixed-Time Stabilization and Tracking Control of a Marine Surface Ship Subjected to Output Constraints

A stabilization control can be used to maintain the position and attitude of the ship, mooring manipulation, and tracking control can force ships to enter the preplanned route from any initial position and finally reach the destination along the route. In this article, both the prespecifiable fixed-time stabilization control and adaptive trajectory tracking control are considered for a kind of fully actuated ocean surface ship under output constraints. Barrier Lyapunov function (BLF) is utilized to remedy with the output limitation constraints. By combining the fixed-time control and switching techniques, and choosing the appropriate symmetric Lyapunov function, the control algorithm of fixed-time stabilization is designed guaranteeing that the closed-loop system state trajectories tend to zero in a fixed time and meanwhile not going beyond the preset operating range in the control process. The adaptive tracking control law is proposed by using the asymmetric BLF and adaptive control technologies. Under the adaptive controller, the output constraints are also achieved, and the tracking errors are adaptively converge to steady zero states, respectively, while keeping all the signals bounded in the control process. The simulations are carried out to demonstrate the effectiveness of the presented control methods.