Development and Test of Lightweight, Low Friction, High Power Hydraulic Actuator for Tough Robots

Abstract

Disaster responding robots mainly uses electromagnetic motors and reducers, but they are weak to shock and spoil robots' toughness. Hydraulic actuators, on the other hand, have not only shock-resistance, but also high F/M ratio and backdrivability. They are useful characters to disaster responding robots. But hydraulic actuators were often used to constructing machines or plant facilities, they are too big, heavy, and high friction to apply them to robots. In this paper, we developed a new hydraulic cylinder for tough robots and conducted evaluation tests. The cylinders realize lightweight by utilizing Multi-Directional Forging magnesium alloy, hi power by setting its driving pressure 35 MPa, and high controllability by applying two types of low frictional pistons: one is utilizing a fluid bearing technology and the other is common combination packing. The cylinder achieved about 4.4 times high F/M ratio to conventional cylinders. And in evaluation tests, they performed minimum driving pressure 0.01 MPa, which is 1/30 smaller friction than conventional cylinders.