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日本語

Wall climbing robots have a wide range of potential applications, including building inspections and maintenance, and search and rescue duties at disaster sites. For robots, climbing straight up vertical walls is a fairly easy goal to accomplish. In the real world however, the robot may have to navigate over obstacles on the wall, such as steps, and transition to walls with different facings. Even if it can reach the top, the robot then faces the most challenging task, which is to traverse the summit over to the other side.

The research team has developed a robot inspired by land leeches, which are excellent climbers in nature. The land leeches, usually found in forests or mountains, can move around complex terrain and walls using two suction cups on each end of their soft extensible bodies. Their bodies are so light and soft that they are relatively shock resistant should they fall from height.

The team designed a new motion mechanism using the tubular structure of a shower hose to mimic the useful qualities of leeches, namely, to be lightweight, flexible and extendable. The flexible tube with a metal plate with an S shaped profile spirally wound is the same kind as found in household use. A gear engages with the helical groove on the surface of the tube. The flexible tube moves back and forth by rotational motion. The robot has a body composed of three flexible tubes that are connected in parallel. The body can bend or elongate by controlling the length of each flexible tube fed by the gear.

The robot successfully achieved upward/downward climbing and horizontal transition on a vertical wall. By combining these two transitions, the robot is capable of moving freely on a two-dimensional wall surface. The robot’s flexible body, with large deformation, enabled it to transition from one side of a vertical wall to the other side. Achieving this level of freedom of movement for a soft and flexible robot represents a world first.

The Ph.D candidate Ayato Kanada, who is in charge of the development and the lead author of the study, says, "I came up with the idea in the bathroom of my house. The shower hose went wild as if it was alive when I inadvertently turned on the faucet at maximum. Then an idea occurred to me that if I could manipulate a hose, I might be able to make a robot which mimics the dynamic movement of a living creature."

Making the most of the hollow structure of the shower hose, the team is considering the possibility of changing the stiffness of the tube by pouring fluid into the cavity. Robots with this kind of flexible body structure are not only highly adaptable to their environment, but also highly secure against collision. As such, they show promise in terms of their potential applications to labor in proximity to humans.

This work was supported by the Grant-in-Aid for JSPS Research Fellow (No. 17J04776), the United Kingdom’s Engineering and Physical Science Research Council (EPSRC) DTP under Award 1476475 and RG92738, and Mathworks Ltd RG90950 378. Ayato Kanada, the first author, was supported by the Program for Leading Graduate Schools conducted by Japan Society for the Promotion of Science of the Ministry of Education, Culture, Sports, Science and Technology.