Wednesday, May 22, 2024

Insect-sized jumping robot adapts to compliant environments

For decades, robot makers have turned to animals and insects to help them understand how to build a machine that can jump, walk, squeeze, and more. If animals and insects can jump across grass and sand, why can’t robots?

Sarah Bergbreiter, Professor of Mechanical Engineering at Carnegie Mellon University, has found that researchers don’t have to look far to enable this in robots.

Existing latch mechanisms that were once thought of as an ‘on’ or ‘off’ switch to release stored energy can also be used to control jump performance across a wide range of terrains.

The team led by Bergbreiter used a mathematical model to illustrate how the latch plays a role in the system’s ability to adapt its jump performance before testing their findings on a robot jumper.

“We found that the latch can not only mediate energy output but can also mediate energy transfer between the jumper and the environment that it is jumping from,” Bergbreiter explains. “When using a round latch, we can delay the jump and allow the robot to take advantage of the substrate’s recoil.”

Researchers tested their jumper on a tree branch and watched as the branch recoiled before the jumper took off. This proved that the jumper recovered some of the energy initially lost to the tree branch.

Surprisingly, the team found that a sharp (zero radius) latch sometimes outperformed their rounded latch, contrary to model predictions. In these instances, the tree branch collides with the robot after take-off, causing an unconventional form of energy recovery from the substrate bump. The bump gave the jumper additional energy enabling it to outperform the well-controlled rounded latch jumper.

“Now that we understand the natural design space, we can build something that takes advantage of the compliance of these soft substrates,” Berbreiter says.

Biologists are equally motivated to understand this space in order to discern how biological organisms, like grasshoppers, are able to control their energy output when jumping through the grass.

“It has been nearly impossible to design controlled insect-sized robots because they are launched in just milliseconds. Now, we have more control over whether our robots are jumping up one foot or three. Or we can simply make it jump consistently despite wide variation in the substrate. It’s really fascinating that the latch – something that we already need in our robots – can be used to control outputs that we couldn’t have controlled before.”

Journal reference:

  1. Sathvik Divi, Crystal Reynaga, Emanuel Azizi and Sarah Bergbreiter. Adapting small jumping robots to compliant environments. Journal of The Royal Society Interface, 2023; DOI: 10.1098/rsif.2022.0778