A study of the control of an underactuated underwater robotic vehicle

Underwater robotic vehicles (URVs), generally, consist of two main classes, namely the remotely operated vehicles (ROVs) and the autonomous underwater vehicles (AUVs). In this paper, a simplified model of a thruster and a general equation of rigid body motion for an underactuated ROV are presented. Then the nonlinear and coupling effects on the ROV, from its shape and design, are derived and presented. Lastly, the steady-state nonlinear behaviour of the thrusters observed are used to design and develop a simple PID controller. Simulation results obtained demonstrated the capability of the controller in the regulating of the desired amount of thrust while maintaining a relatively small degree of steady-state error.