Trajectory Tracking Controller of Underwater Vehicle with Model Uncertainties and External Disturbances

Abstract

AbstractThis paper designed a trajectory tracking controller for an underwater vehicle considering model uncertainties and external force disturbances using the Port-Hamiltonian (PH) control theory. Firstly, the mathematical model of the underwater vehicle is established and expressed under the PH framework. However, the hydrodynamic force coefficients inside the mathematical model are hard to obtain accurately without detailed towing tank experiments. To address this, we will propose a parameter observer to estimate the unknown parameters caused by model uncertainties. Meanwhile, the vehicle inevitably suffers from external unknown force disturbances driven by current and wind. So another observer based on passivity theory is proposed to address the unknown fore disturbance. The control law is derived from reshaping kinetic energy and injecting damping terms via the interconnection and damping assignment passivity-based control method. This proposed controller has a physical interpretation. Moreover, it has been proved that the proposed controller can enable vehicles to track the desired trajectory and minimize the tracking errors exponentially. Numerical simulations and comparisons illustrate the stability and effectiveness of the proposed controller to model uncertainties and unknown external disturbances.KeywordsUnmanned underwater vehiclePort-controlled Hamiltonian systemTrajectory tracking control