Adaptive control of unmanned surface vessels matching an optimized reference model

In this paper, adaptive control of unmanned marine surface vessel has been investigated in the presence of uncertain dynamics as well as external disturbance. Variable structure technique has been utilized in the control design to make the dynamic response and desired motion tracking as quickly as possible. In practice, usually the desired trajectories are given as step points, such that direct immediate tracking would cause large acceleration and huge control effort, while the latter may be out of the actuators' limitation. Therefore, a reference model approach is employed, such that instead of direct tracking of the desired set point, the control objective becomes to shape the closed-loop dynamics to match a reference model. The reference model is built using optimization technique which tries to minimizes both tracking error and motion acceleration, and subsequently control effort. The smooth tracking is thus guaranteed in an optimal manner.