Tube actuator with drawing out drive aimed for the inspection in the narrow and curved path

This paper describes a tube actuator aimed for a robot to inspect in the narrow and curved path. The tube is made of silicone, and its surroundings are restrained. This actuator has mainly two functions: enabling advancing of the robot, and enabling it to curve into the desired direction. The advancing motion is promoted by pressuring, which draws out the folded tube, and the curving motion is achieved by changing the restraining condition of surroundings of the tube. Preliminary experiments showed that the tube can curve 90 degrees under the pressure of 0.2MPa. Furthermore, to curve the tube into desired direction, the restraining material can be made of water-soluble film or thermoplastic film, which changes its mechanical properties under certain conditions. Using this actuator, the developed robot was able to advance through narrow path and curve through the path in directions of three dimensions.