Adaptive Non-singular Terminal Sliding Mode Control for an Unmanned Underwater Vehicle: Real-time Experiments

This research work focuses on the design of a robust-adaptive control algorithm for a 4DOF Unmanned Underwater Vehicle (UUV). The proposed strategy is based in a Non-Singular Terminal Sliding Mode Control (NTSMC) with adaptive gains, where the proposed adaptation mechanism ensures that the gains remain bounded. In this control strategy a non-singular terminal sliding surface is proposed to obtain a faster convergence of the tracking errors. The NTSMC ensures Practical Finite-Time Stability for the closed-loop system as well as exhibits a chattering reduction. In order to demonstrate the satisfactory performance of the proposed controller, a set of experiments was performed with a Non-Singular Terminal Sliding Mode Controller and an Adaptive Non-Singular Terminal Sliding Mode Control (ANTSMC) in real time for trajectory tracking in the X-Y plane, the graphs showed that the ANTSMC converges faster to a smaller region and reduces oscillations.