Design of a Motion Controller for an Underwater Vehicle-Manipulator System with a Differently-Controlled Vehicle

This paper deals with a motion control scheme for autonomous underwater robots equipped with manipulators. It is pointed out in the literature on underwater robotics that the robot body propelled by marine thrusters generally has a considerably slower time response than the manipulator driven by electric motors. Moreover, for a real system, it is generally difficult to precisely control the position of a vehicle floating in water by means of hydrodynamic effects produced by the rotations of thrusters' propellers. In this paper, we develop a motion controller for the manipulator in consideration of the thruster dynamics including a control input of the vehicle under the condition that the vehicle is differently controlled by a motion controller that can achieve not a precise control performance but a motion stability in the presence of disturbances such as water waves or a water current.