Simulation and experiment study on deformation characteristics of the water hydraulic flexible actuator used for the underwater gripper

Abstract

A water hydraulic flexible gripper with three-fingered structure is developed to deal with the problem of poor adaptability for the existing underwater gripper. This gripper driven by water hydraulics can realize flexible grasping and possess simple structure, high pressure-bearing, strong adaptability and capability of anti-jamming to the water environment and easy to control. In particular, the water hydraulic flexible gripper system is an open system in relation to the underwater environment, with the water source being supplied directly by the underwater environment, eliminating the effects of back pressure generated by the underwater environment in comparison with the closed system of other grippers. It is a good solution to solve the problem of poor adaptability for the existing underwater gripper in underwater environment. The flexible actuator model is established to explore the key parameters influencing the deformation characteristics. The effects of different inlet pressure, knuckle length, wall thickness and material of the inner skeleton and external surface on the deformation characteristics of the flexible actuator are investigated through simulation. It is found that, for the flexible actuator, the wall thickness of the inner skeleton is selected as 1 mm and the inner skeleton length is designed with the first knuckle of 30 mm and the second knuckle of 80 mm. Based on the optimal parameters obtained through simulation, the prototype of flexible actuator and flexible gripper are fabricated. Experiment is performed to test the deformation of the flexible actuator under different inlet pressure. It is found that the experiment results are consistent with the simulation results. Both of the experiment and simulation results exhibit that the total deformation of the flexible actuator is proportional to the inlet pressure. The research will lay foundation for the optimal design of flexible actuator used for the underwater gripper driven by water hydraulics.