In this report, a robust controller for underwater robots equipped with a manipulator (underwater robot manipulators) is developed to overcome uncertainties in robot dynamics and hydrodynamic forces. The proposed controller has the following features : (1) the structure of the controller is very simple in comparison with that of an adaptive controller using a regressor of a robot dynamic equation； (2) the controller is developed without using a function specific to sliding mode type robust control, such as a signum function and a saturation function, which often leads to oscillations in control inputs； and (3) the maximum value of a tracking error norm can be arbitrarily reduced by setting controller design parameters. Furthermore, numerical simulations whose model is a 2 link planar underwater robot manipulator are performed. The simulation results demonstrate the validity of the theoretical results (the controller features).
Fishery engineering
Underwater robot
Manipulator
Robust control
Time-varying feedback gain