Adaptive FractionalOrder FastTerminalType Sliding Mode Control for Underwater VehicleManipulator Systems

Abstract

This article proposes an adaptive fractionalorder fastterminaltype sliding mode control method to solve the trajectory tracking problem of the underwater vehiclemanipulator system in the presence of large dynamic uncertainties and strong external disturbances. For improving the control continuity and accuracy of the conventional sliding mode control method, a modified fractionalorder sliding mode control scheme with a novel fractionalorder sliding manifold and a fastterminaltype reaching law is proposed. In addition, an autotuning law of switching gains is presented and combined with the fractionalorder sliding mode control scheme to overcome the problem that the fixed switching gain may lead to obvious tracking performance degradation under complicated lumped disturbances. Finally, the superiorities of the proposed adaptive fractionalorder fastterminaltype sliding mode control method are verified through a series of comparative simulations of a 6degreesoffreedom (DOF) UVMS carrying a 6DOF manipulator.