Adaptive Backstepping Control for Underactuated 6-DoF USV with Uncertain Dynamics

This paper introduces a target tracking control approach for an underactuated Unmanned Surface Vehicle (USV) with 6 Degrees of Freedom (6-DoF), characterized by unknown dynamics and disturbances. Notably, the system inertia matrix of this 6-DoF USV is positive definite and non-diagonal, implying the presence of intricate coupling relationships within the input vector components. To address the challenges posed by underactuation, we present an adaptive control methodology utilizing a novel transverse function and backstepping procedure. Furthermore, we introduce a dynamic signal to compensate for external dynamic uncertainties and disturbances. Leveraging Lyapunov stability theory, we establish that the target tracking error converges to a small neighborhood near the origin, and all signals within the closed-loop system remain bounded. Lastly, we showcase the effectiveness of the proposed control methodology through simulation results involving a 6-DoF supply vehicle.