New Insect-Sized Robot Withstands the Weight of an Average Human

The sight of a scurrying bug can make individuals look away because they probably feel uneasy. Now, a novel insect-sized robot developed by scientists at the University of California, Berkeley (UC Berkeley), can skitter across the floor at almost the speed of a darting cockroach.

The robot is also almost as hardy as a cockroach. Most probably, it would simply keep moving even if it is squashed under one’s foot.

Most of the robots at this particular small scale are very fragile. If you step on them, you pretty much destroy the robot. We found that if we put weight on our robot, it still more or less functions.

Liwei Lin, Study Senior Author and Professor of Mechanical Engineering, UC Berkeley

Such small-scale robots could be useful in search and rescue operations, squishing and squeezing into places where humans or dogs cannot fit, or where it might be very risky for them to go, stated Yichuan Wu, study first author, who concluded the work when he was a graduate student in mechanical engineering at UC Berkeley via the Tsinghua-Berkeley Shenzhen Institute partnership.

“For example, if an earthquake happens, it’s very hard for the big machines, or the big dogs, to find life underneath debris, so that’s why we need a small-sized robot that is agile and robust,” stated Wu, who is currently an assistant professor at the University of Electronic Science and Technology of China.

The results of the study were recently reported in the journal, Science Robotics.

The robot is roughly the size of a massive postage stamp and is composed of a thin sheet of a piezoelectric material known as polyvinylidene fluoride, or PVDF in short. Piezoelectric materials are considered as unique products because when an electric voltage is applied to them, they tend to contract or expand.

The scientists initially coated the PVDF in an elastic polymer layer, which makes the whole sheet to bend, rather than contract or expand. Next, they added a front leg because when the material straightens and bends under an electric field, the device is pushed forward in a “leapfrogging” motion by the oscillations.

While the ensuing robot may be rather simple to look at, it possesses some incredible abilities. It can scurry across the ground at a speed of 20 body lengths per second—a pace that is similar to that of a cockroach and established to be the fastest speed among insect-scale robots. The robot can climb small slopes, zip through tubes, and carry tiny loads, for example, a peanut.

The most impressive feature is that the robot, weighing less than one-tenth of a gram, can endure a weight of about 60 kg—approximately the weight of a normal human—which is about one 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. 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.

Liwei Lin, Study Senior Author and Professor of Mechanical Engineering, UC Berkeley

At present, the robot is “tethered” to a thin wire carrying an electric voltage that fuels the oscillations. The researchers are attempting to add a battery so that the robot can roam autonomously. They are also exploring ways to include gas sensors and are enhancing the robot’s design so that it can be guided around obstacles.

The study co-authors 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.

The research is partly supported by the Berkeley Sensor and Actuator Center, an Industry-University Cooperation Research Center.

A new insect-sized robot scurries at the speed of a cockroach and can withstand the weight of a human. (Video credit: Stephen McNally)