Newly developed beetle-inspired robot uses elastic energy

It is powerful enough to maneuver over obstacles.
Nergis Firtina
Click beetle-sized robots.
Click beetle-sized robots.

University of Illinois 

The University of Illinois researchers’ newly developed insect-sized jumping robots will do tasks in small and tight places. The creation of jumping robots is also a significant advance in mechanical, agricultural, and search-and-rescue environments, according to the university.

Led by Prof. Sameh Tawfick, a new study demonstrates a succession of click-beetle-sized robots that are quick enough to match an insect's speedy escape time, powerful enough to maneuver over obstacles, and small enough to slip into confined spaces.

Over the past ten years, scientists at Princeton University and the University of Illinois Urbana-Champaign have investigated the click beetle's anatomy, mechanics, and evolution. A 2020 study discovered that a coiled muscle within a click beetle's thorax snap buckles, releasing elastic energy quickly, enabling them to launch themselves in the air several times their body length as a means of righting themselves if they are flipped onto their backs.

“One of the grand challenges of small-scale robotics is finding a design that is small yet powerful enough to move around obstacles or quickly escape dangerous settings,” Prof. Tawfick said.

They used tiny coiled actuators

Tawfick and his team used tiny coiled actuators that pull on a beam-shaped mechanism, causing it to gradually buckle and store elastic energy before it is spontaneously released and amplified, propulsion the robots upward. 

“This process, called a dynamic buckling cascade, is simple compared to the anatomy of a click beetle,” Tawfick said. “However, simple is good in this case because it allows us to work and fabricate parts at this small scale.”

The team constructed and tested four device variants using mathematics and biological evolution as their guides, eventually settling on two configurations that can jump effectively without human assistance.

“Moving forward, we do not have a set approach on the exact design of the next generation of these robots, but this study plants a seed in the evolution of this technology – a process similar to biologic evolution,” Prof. Tawfick added.

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The team believes these robots will be able to enter small locations and assist with maintenance on massive devices like jet engines and turbines, for example, by collecting images of potential issues.

“We also imagine insect-scale robots being useful in modern agriculture,” Tawfick said. “Scientists and farmers currently use drones and rovers to monitor crops, but sometimes researchers need a sensor to touch a plant or to capture a photograph of a very small-scale feature. Insect-scale robots can do that."

The study was published in PNAS on January 23.

Study abstract:

Millions of years of evolution have allowed animals to develop unusual locomotion capabilities. A striking example is the legless jumping of click beetles and trap-jaw ants, which jump more than 10 times their body length. Their delicate musculoskeletal system amplifies their muscles’ power. It is challenging to engineer insect-scale jumpers that use onboard actuators for both elastic energy storage and power amplification. Typical jumpers require a combination of at least two actuator mechanisms for elastic energy storage and jump triggering, leading to complex designs having many parts. Here, we report the new concept of dynamic buckling cascading, in which a single unidirectional actuation stroke drives an elastic beam through a sequence of energy-storing buckling modes automatically followed by spontaneous impulsive snapping at a critical triggering threshold. Integrating this cascade in a robot enables jumping with unidirectional muscles and power amplification (JUMPA). These JUMPA systems use a single lightweight mechanism for energy storage and release with a mass of 1.6 g and 2 cm in length and jump up to 0.9 m, 40 times their body length. They jump repeatedly by re-engaging the latch and using coiled artificial muscles to restore elastic energy. The robots reach their performance limits guided by theoretical analysis of snap-through and momentum exchange during the ground collision. These jumpers reach the energy densities typical of the best macroscale jumping robots, while also matching the rapid escape times of jumping insects, thus demonstrating the path toward future applications including proximity sensing, inspection, and search and rescue.

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