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Insect-sized robot moves with the agility of a cheetah

Professional Engineering

The tiny insect-like robot uses electrostatic forces to move quickly and nimbly (Credit: UC Berkeley photo courtesy of Jiaming Liang & Liwei Lin)
The tiny insect-like robot uses electrostatic forces to move quickly and nimbly (Credit: UC Berkeley photo courtesy of Jiaming Liang & Liwei Lin)

A new insect-sized robot can swerve and pivot with the agility of a cheetah, letting it traverse complex terrain and quickly move around obstacles.

Engineers at the University of California Berkeley developed the robot, which uses electrostatic adhesion in its ‘footpads’ for nimble navigation. The same principle gives some insects the ability to scurry up walls and walk upside down on ceilings.

The robot was constructed from a thin, layered material that bends and contracts when an electric voltage is applied. In a 2019 paper, the research team demonstrated that this simple design can be used to create a cockroach-sized robot that can scurry across a flat surface at a rate of 20 body lengths per second, or about 2.4km/h — nearly the speed of actual cockroaches, and the fastest relative speed of any insect-sized robot.

In a new study, the research team added two electrostatic footpads to the robot. Applying a voltage to either of the footpads increases the electrostatic force between the footpad and the surface, making that footpad stick more firmly to the surface and forcing the rest of the robot to rotate around the foot.

The two footpads give operators full control over the trajectory of the robot, and allow the robot to make turns with a centripetal acceleration that exceeds most insects.

“Our original robot could move very, very fast, but we could not really control whether the robot went left or right, and a lot of the time it would move randomly, because if there was a slight difference in the manufacturing process — if the robot was not symmetrical — it would veer to one side,” said Liwei Lin, professor of mechanical engineering at UC Berkeley. “In this work, the major innovation was adding these footpads that allow it to make very, very fast turns.”

To demonstrate the robot’s agility, the research team filmed the robot navigating Lego mazes while carrying a small gas sensor and swerving to avoid falling debris.

Because of its simple design, the robot can also survive being stepped on by a 54kg human.

Small, robust robots like these could be ideal for search and rescue operations or investigating other hazardous situations, such as scoping out potential gas leaks, Lin said. While the team mostly demonstrated the robot while it was powered and controlled through a small electrical wire, they also created an untethered version that can operate on battery power for up to 19 minutes and 31 metres while carrying a gas sensor.

“One of the biggest challenges today is making smaller scale robots that maintain the power and control of bigger robots,” Lin said. “With larger-scale robots, you can include a big battery and a control system, no problem. But when you try to shrink everything down to a smaller and smaller scale, the weight of those elements becomes difficult for the robot to carry and the robot generally moves very slowly. Our robot is very fast, quite strong, and requires very little power, allowing it to carry sensors and electronics while also carrying a battery.”

Lin is senior author of a paper describing the robot, which appeared in Science Robotics.

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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.


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