Fuzzy Adaptive Impedance Control for Deep-Sea Hydraulic Manipulator Grasping Under Uncertainties

This paper presents a position-based fuzzy adaptive variable impedance control architecture for an end-effector of deep-sea hydraulic manipulators. To obtain the contact force information in the deep-sea environment, pressure sensors are used to take the place of force sensors on deep-sea hydraulic manipulators. The stiffness and position information of underwater objects are can not be known in most cases, in order to get the reference trajectory, a method of on-line parameters estimation by the Lyapunov equation is proposed. To deal with the stiffness variation of objects and improve the robustness, a position-based fuzzy adaptive impedance controller is designed. Simulation and experiment studies are carried out to evaluate the effectiveness of the proposed control method applied for the end-effector of deep-sea hydraulic manipulators.