A robotic thruster that can handle hairy flexible cable of serpentine robots for disaster inspection

Snake-like robots are useful for exploring narrow spaces such as in collapsed buildings after a severe disaster. Two people are usually required for operating serpentine robot, one for pushing and twisting, and the other for controlling the tip. In this paper, we propose a way to control a snake robot with a single operator, by the use of robotic thruster. Further, a robotic thruster has the advantage of improving the estimation of tip position and shape, by measuring the inserted length of the cable. In this study, the focus is on 'hairy' robots, so called because an Active Scope Camera (ASC) is covered by inclined cilia acting as a self-propelling mechanism. When operating a snake robot, the most difficult challenge is to insert it without damaging the cilia. First, opposed flexible rollers are proposed to push the robot whose cylindrical surfaces are covered by tensed flexible wires. The wires sandwich the robotic body between the hairs to avoid damage. Then, by using the rollers, a thruster is proposed which can push and twist the ASC, and measure both the inserted length and twisting angles. Basic performance experiments showed that the thruster could successfully push and twist an ASC of approximately 5 m. The accuracy of the inserted length and twisting angle were less than 10% and 45%, respectively. The thruster was able to push and twist the ASC on flat environments with obstacles, and in a three-dimensional rubble environment.