Underactuated Autonomous Underwater Vehicle Trajectory Tracking Control in Three Dimensions Based on Fractional Order Sliding Mode

This paper proposes a Finite-Time Fractional-Order Sliding Mode Controller (FTFOSMC) for the three-dimensional trajectory tracking of an underactuated Autonomous Underwater Vehicle (AUV) using only three available control inputs - the rudder, diving plane, and rotating propeller. The controller uses a Finite-Time Integral Sliding Mode Control in the first step to quickly and accurately reduce tracking errors. In the second step, fractional calculus is introduced to enhance the control system’s robustness. The stability of the control system is proven by Lyapunov stability analysis, and the convergence time’s upper bound is calculated. Simulation results validate the effectiveness of the proposed controller.