You Can't Squash This Cockroach Inspired Robot

Credit: UC Berkeley photo by Stephen McNally

The robot, which is about the size of a large postage stamp, is made of a thin sheet of a piezoelectric material called polyvinylidene fluoride, or PVDF. Piezoelectric materials are unique, in that applying electric voltage to them causes the materials to expand or contract.

The researchers coated the PVDF in a layer of an elastic polymer, which causes the entire sheet to bend, instead of to expand or contract. They then added a front leg so that, as the material bends and straightens under an electric field, the oscillations propel the device forward in a “leapfrogging” motion.

The resulting robot may be simple to look at, but it has some remarkable abilities. It can sail along the ground at a speed of 20 body lengths per second, a rate comparable to that of a cockroach and reported to be the fastest pace among insect-scale robots. It can zip through tubes, climb small slopes and carry small loads, such as a peanut.

Perhaps most impressively, the robot, which weighs less than one tenth of a gram, can withstand a weight of around 60 kg — about the weight of an average human — which is approximately 1 million times the weight of the robot.

“People may have experienced that, if you step on the cockroach, you may have to grind it up a little bit, otherwise the cockroach may still survive and run away,” Lin said. “Somebody stepping on our robot is applying an extraordinarily large weight, but [the robot] still works, it still functions. So, in that particular sense, it’s very similar to a cockroach.”

The robot is currently “tethered” to a thin wire that carries an electric voltage that drives the oscillations. The team is experimenting with adding a battery so the robot can roam independently. They are also working to add gas sensors and are improving the design of the robot so it can be steered around obstacles.

Co-authors of the paper include Justin K. Yim, Zhichun Shao, Mingjing Qi, Junwen Zhong, Zihao Luo, Ronald S. Fearing and Robert J. Full of UC Berkeley, Xiaojun Yan of Beihang University and Jiaming Liang, Min Zhang and Xiaohao Wang of Tsinghua University.

This work is supported in part by the Berkeley Sensor and Actuator Center, an Industry-University Cooperation Research Center.

Contacts and sources:University of California – Berkeley

Citation: Insect-scale fast moving and ultrarobust soft robot.
Yichuan Wu, Justin K. Yim, Jiaming Liang, Zhichun Shao, Mingjing Qi, Junwen Zhong, Zihao Luo, Xiaojun Yan, Min Zhang, Xiaohao Wang, Ronald S. Fearing, Robert J. Full, and Liwei Lin.Science Robotics, 2019 DOI: 10.1126/scirobotics.aax1594