LMI-based anti-windup control for an underwater robot with propellers saturations

This paper addresses the steering control of an underwater robot in the presence of propellers saturation. A linear model with input saturation is established from the general equation of motion. A two-step LMI-based design procedure is presented. First, we seek a linear time invariant (LTI) which achieves tight nominal performance when the command input does not saturate. Then, an extra anti-wind up compensator is designed to ensure the absolute stability of the closed loop system against sector bounded nonlinearity. Existence conditions for the two control structures can be cast as optimization problems over linear matrix inequalities. Lastly, this approach is applied to design the steering controller for the Phanthom 500 underwater robot.