Leech-inspired soft robot can climb walls

Scientists have developed a soft, flexible robot that resembles a leech and can climb up a wall. Wall climbing robots have a wide range of potential application, including building inspection and maintenance, and search and rescue tasks at disaster sites.

The team from Toyohashi University of Technology in Japan and University of Cambridge in the UK created LEeCH (Longitudinally Extensible Continuum-robot inspired by Hirudinea) with material used for shower hose, and two suction cups.

Climbing straight up vertical walls is fairly easy to accomplish, however, in reality, the robot may have to navigate over obstacles on the wall such as steps and transition to walls with different directions, researchers said. The hardest task is to reach the other side of the wall. A robot capable of climbing up to the top of the wall has to face extreme difficulty in traversing the summit over to the other side.

"I came up with the idea in the bathroom of my house. The shower hose went wild as if it had a life when I inadvertently turned on the faucet at maximum," said Ayato Kanada, lead author of the study published in the journal Soft Robotics. "Then an idea occurred to me that if I could manipulate a hose, I might be able to make a robot with dynamic movement of living creature," Kanada said in a statement.

The 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 both ends of bodies and soft extensible bodies. Their bodies are so light and soft that they are not subject to great damage from a fall from height.

The team designed a new motion mechanism using tube structure of shower hose to mimic the advantageous properties of leeches, namely, lightweight, flexible and extensible. The flexible tube with a metal plate with S shaped profile spirally wound has been used in general households.

A gear engages with the helical groove on the surface of the tube. The flexible tube moves back and forth by the 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. This is the world's first achievement in developing soft and flexible robot that is capable of free movement on a wall, researchers said.