A coupled and self-adaptive fluid-actuated finger for flexible pinch and power grasp

The conventional underactuated fingers usually adopt rigid transmission mechanisms to achieve coupled pinch or self-adaptive grasp. It often confused researchers how to produce and keep contact forces to achieve stable grasp. This paper designs a novel coupled and self-adaptive fluid-actuated (COSAF) finger for flexible pinch and power grasp of fingers, which can lock the motion conveniently and combine the abilities of coupled fingers and self-adaptive fingers. The key of the COSAF finger is a fluid transmission mechanism with single-direction valves, which adopts fluid as the force transmitting medium to realize the pinching and enveloping grasp. Due to the utilization of single-direction valves, the backward motions can be locked. Analysis results show that the relationship of the rotation speeds of two joints is linear during coupling process, and it is convenient to change coupling character of the finger through changing the radiuses of flexible pipes.