Robust attitude stabilization of an underactuated AUV

Robustness to actuator failures may be obtained by changing to a control law that controls the vehicle using only the remaining actuators, when an actuator failure is detected. Such a control law is in this paper proposed for attitude stabilization of an AUV with only two control torques. To this end, a stability result for a class of homogeneous time-varying systems is presented. The proposed control law is a continuous, periodic time-varying feedback law. It provides exponential stability that does not depend on exact knowledge of the model parameters, and the exponential stability of the controlled system is thus robust to uncertainties in the model parameters.