Dynamic positioning of a marine vessel using DTVSC and robust control allocation

This paper presents a discrete-time variable-structure control (DTVSC) for the dynamic positioning system of a marine vessel. The DTVSC guarantees robustness with respect to environmental disturbances. Moreover, the allocation problem, in the case of vessels with azimuth thrusters, represents a challenging problem since a non-convex nonlinear problem must be solved. In this paper, the allocation problem is solved using the Damped Least Squares method. The proposed solution is compared with a PID-based control. Reported simulations show that the proposed solution produces better performance.