Adaptive Robust Tracking Control of Deep Sea Manipulator: Theory and Experiments

The underwater hydraulic manipulator's challenging working condition, such as the unknown payload, varying speed, and hydraulic actuator’s dynamics, makes common controller invalid. In this paper, based on the nonlinear control theory, the adaptive robust control method is proposed to enhance the joint tracking accuracy, the controller can also compensate the interactive dynamic effects between manipulator links. The deep-sea manipulators are just equipped with angular sensors, so an observer which can provide the smooth angular velocity estimation is designed. By using the Lyapunov approach, the proposed controller can be proved asymptotically stable for trajectory tracking. The comparative experiments are conducted on a deep-sea hydraulic manipulator, experiment results show the control algorithm could provide a fast, high accuracy tracking, and guarantee the tracking performance when subjected to payload change or different reference speed.