An underwater manipulator mounted on a semi-autonomous underwater vehicle (SAUV) is under developing in KRISO (Korea Research Institute of Ships and Ocean Engineering) for light work mission. This paper describes the physical configuration and controller of the underwater vehicle-mounted manipulator system (UVMS), and proposes a modified non-regressor based adaptive controller for trajectory tracking of the UVMS. The adaptive controller makes the system stable, and automatically tunes the parameters against for the variation of system uncertainties and of external disturbances due to hydrodynamic forces. Computer simulation for position tracking of the UVMS was performed to evaluate the performance of the non-regressor based adaptive controller. The results demonstrate the effectiveness of the proposed controller that achieves the desired tracking performance and the convergence of the estimated parameters.
An underwater manipulator mounted on a semi-autonomous underwater vehicle (SAUV) is under developing in KRISO for light work mission. The underwater manipulator mounted on the vehicle is a multibody dynamic system. The hydrodynamic coefficients are often poorly known and the dynamics of the manipulator and of the vehicle can change considerably according to the speed and direction of the manipulator's motion as well as the vehicle's. Furthermore, it is difficult to design a control system for the UVMS, since slowly varying motion of the vehicle generates non-linear disturbances on the base of the manipulator. The control of underwater manipulators for high performance in terms of speed and accuracy is a challenging task mainly because the manipulator dynamics are time-varying and nonlinear. Effects of nonlinear terms and strong couplings between the joints and the vehicle become significant especially for the fast motion. The system is also subject to uncertainties due to joint friction, payload change, sensor noise, external disturbance, etc.
