A Flexible In-Pipe Robot Capable of Moving in Open Spaces via a Pneumatic Rotary Mechanism

In this paper, we propose a flexible pneumatic robot that can move in narrow pipes and across open spaces. The development of such robots is necessary to access the insides of Fukushima Daiichi Nuclear Power Plant's pressure containment and reactor pressure vessels via pipes and to then move around inside and investigate damage to them. The novel flexible pneumatic robot proposed here realizes both in-pipe and open-space locomotion by integrating expansion-type pneumatic hollow-shaft actuators and a pneumatic rotary steering mechanism. We first present the propulsion and steering concept of the proposed robot before detailing its design and the developed prototype. Further, we present the experimental evaluation of the characteristics and performances of the steering and propulsion mechanisms. We found that each expansion-type pneumatic hollow-shaft actuator can generate a maximum traction force of 11 N, whereas the steering mechanism generates a maximum steering force of 0.55 N. Finally, we conducted a trial to confirm the locomotion performance of the robot both in pipes and across open space. The results show that the robot can smoothly touch down into open space from high-lying pipes and subsequently move around across open spaces toward a given coordinate.