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HOME > No.18, Sep 2019 > A wall-climbing robot – inspired by the soft body of a leech

A wall-climbing robot – inspired by the soft body of a leech

180 degree rotation from one side of the wall to the otherBy Tomoaki Mashimo
Tomoaki Mashimo (left) with Ph.D candidate, Ayato Kanada

A research team led by Associate Professor Tomoaki Mashimo of the Department of Mechanical Engineering at Toyohashi University of Technology, in collaboration with Dr. Fumiya Iida, Reader in Robotics at the department of Engineering at the University of Cambridge, has successfully developed a leech-shaped robot, "LEeCH" (Longitudinally Extensible Continuum-robot inspired by Hirudinea), which can climb vertical wall. LEeCH is capable of elongating and bending its body without any constraints; just like a leech. Thanks to its flexible body structure and the suction cups, the robot has successfully climbed a vertical wall and even reached the other side of the wall. The study was published in Soft Robotics, an American scientific journal, on March 27, 2019.

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.

Movie of the wall-climbing robot experiment

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."

Schematic of proposed climbing robot. (a) Real leech. (b) LEeCH (Longitudinally Extensible Continuum-robot inspired by Hirudinea).

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.


Ayato Kanada, Fabio Giardina, Toby Howison, Tomoaki Mashimo, Fumiya Iida, "Reachability Improvement of a Climbing Robot based on Large Deformations induced by Tri-Tube Soft Actuators," Soft Robotics.

ヒルの柔らかい体に学ぶ — 壁登りロボット

By 真下 智昭

豊橋技術科学大学機械工学系 真下智昭准教授らとケンブリッジ大学工学部 飯田史也准教授らの研究チームは、垂直な壁を登るヒル型ロボット「LEeCH」を開発しました。LEeCH(Longitudinally Extensible Continuum-robot inspired by Hirudinea)は、シャワーのホースを素材とした柔軟な体と2つの吸盤を持っており、本物のヒルのように自在に伸びたり曲がったりすることが可能です。柔らかい構造と吸盤を活かすことで、垂直な壁を登りさらに壁の反対側まで移動することを可能としました。本研究の結果は、3月27日に米国の科学雑誌Soft Roboticsに掲載されました。







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Researcher Profile

Tomoaki Mashimo
Name Tomoaki Mashimo
Affiliation Department of Mechanical Engineering
Title Associate Professor
Fields of Research Actuator/ Mechatronics/ Robotics/ Ultrasonic