A STUDY OF A CRAWLING DEVICE IN IMITATED-EARTHWORM ROBOT

Imitating the course of the earthworm crawling in the hole, a kind of driving device of robot, which creeps in the hole, is studied. The device mainly consists of shape memory alloy(SMA), expansive pressing ring, SMA helix spring, and deflection pressing spring, which can carry out radial bulge, lengthways shrink and lengthways elongate and so on. The actions of SMA elements are completed by turning on or off the electric current through them. The SMA expansive pressing ring keeps close to the wall of the hole when it is electrified and relaxes when it is turned off;SMA helix spring shrinks as it is turned on and elongates as it is turned off deflection pressing spring. The process of the device action is controlled and harmonized by computer. The device has advantages of simple structure, small volume, lightweight, excellent flexibility and convenient control. It is actually applied in Electrical Discharge Manufacturing bent hole. The system composition, working principles;designing cruces and the mode of control are discussed in this paper.