Fully actuated model-based control with six-degree-of-freedom coupled dynamical plant models for underwater vehicles: Theory and experimental evaluation

This paper reports a comparative experimental evaluation of one non-model-based proportional derivative (PD) six-degree-of-freedom (6-DOF) controller and two model-based 6-DOF controllers designed to enable low-speed, neutrally buoyant, and fully actuated underwater vehicles to perform 6-DOF set-point regulation and trajectory tracking. We show analytically that the non-model-based PD controller provides locally asymptotically stable set-point regulation, and we show analytically that the model-based controllers provide locally asymptotically stable 6-DOF trajectory tracking. Numerical simulation studies are reported that corroborate the analytical stability results. We report the first comparative experimental evaluation of three different control algorithms for dynamic 6-DOF trajectory tracking of fully actuated underwater vehicles. Experimental results with the Johns Hopkins University remotely operated vehicle (JHU ROV) show that the model-based controllers’ mean absolute position and velocity tracking error is significantly smaller than the non-model-based PD controller for coupled maneuvers. The model-based controllers are shown to outperform the non-model-based controllers over a wide range of variations in the magnitude of derivative feedback gain. The velocity tracking error of the model-based controllers is shown to be on the same order of magnitude as the measurement error of the velocity sensing instrumentation.