Robust control of overactuated autonomous underwater vehicle

This paper presents a robust control scheme for an over-actuated autonomous underwater vehicle. Since the vehicle is over actuated, a control allocation method is required in conjunction with baseline control law to efficiently distribute control demand to the control effectors. The baseline control law is based on robust H
∞
control. Performances of two control allocation techniques combined with H
∞
control are compared and evaluated. First one is the Explicit Ganging which is an unconstrained control allocation method and, the second one is constrained control allocation method namely Redistributed Pseudo Inverse (RPI) method. Both control allocation techniques are compared using nonlinear six-degree-of-freedom simulation for the cases where some of the control effectors reach their saturation limits. It is shown by simulation results that the RPI method gives an improved performance as compared to the Explicit Ganging for regions where control effectors limit.