Researchers at NASA's Jet Propulsion Laboratory (JPL) were inspired by origami when they developed the Pop-Up Flat Folding Explorer Robot (PUFFER). Its lightweight design — which can hitch a ride aboard a rover — can flatten itself, tucking in its wheels and crawling into places that larger robots can't fit. Over the past year and a half, PUFFER has been tested in a range of rugged terrains, from the Mojave Desert in California to the snowy hills of Antarctica. The idea is to explore areas that might be too risky for a full-fledged rover to go, such as steep slopes or behind sand dunes.

PUFFER crawls under a ledge during field testing. The advantage of its small size and foldable body is that the bot can wedge itself into small spaces. That could be useful on the rugged terrain of other planets. (Credit: NASA/JPL-Caltech)

PUFFER is designed to skitter up 45-degree slopes, investigate overhangs, and even drop into pits or craters. It's meant to be the hardy assistant to a larger robot companion, and several of the microbots can be flattened like cards and stacked one on top of the other. Then, they can be flicked out, popped up, and begin exploring. JPL researchers hope to see PUFFER rolling across the sands of Mars someday. But they imagine it could be used by scientists right here on Earth, as well.

Carolyn Parcheta, a JPL scientist who uses robots to explore volcanoes, offered guidance on PUFFER's science instruments. She said the use of backpack-ready bots has enormous potential for fields like geology. “Having something that's as portable as a compass or a rock hammer means you can do science on the fly,” she said.

Paper Prototype

PUFFER's body was originated by project manager Jaakko Karras, who was experimenting with origami designs. While he was a grad student at UC Berkeley's Biomimetic Millisystem Lab, he worked on developing robotics based on natural forms, such as animal and insect movements. The PUFFER team substituted paper with a printed circuit board that can incorporate more electronics, including control and rudimentary instruments.

“The circuit board includes both the electronics and the body, which allows it to be a lot more compact,” said Christine Fuller, a JPL mechanical engineer who worked on PUFFER's structure and tested it for reliability. “There are no mounting fasteners or other parts to deal with. Everything is integrated to begin with.”

JPL's Kalind Carpenter, who specializes in robotic mobility, made four wheels for the folding bot on a 3D printer. Their first prototype was little more than rolling origami, but it quickly grew more complex. The wheels evolved, going from four to two, and gaining treads that allow PUFFER to climb inclines. They can also be folded over the main body, allowing the bot to crawl. A tail was added for stabilization, and solar panels on PUFFER's belly allow it to flip over and recharge in the sun.

The team partnered with the Biomimetic Millisystems Lab, which developed a “skittering walk” that keeps the bot inching forward, one wheel at a time, without slipping. A company called Distant Focus Corp., Champaign, IL, provided a high-resolution microimager sensitive enough to see objects that are just 10 microns in size — a fraction of a diameter of a human hair.

From the Mojave to Mars

Once they had a functional prototype, the JPL team took PUFFER out for field testing. In Rainbow Basin, California, the bot clambered over sedimentary rock slopes and under overhangs. That terrain serves as an analog to Martian landscapes. On Mars, overhangs could be sheltering organic molecules from harmful radiation. Darkly colored Martian slopes, which are of interest to scientists, are another potential target. On a level dirt path, PUFFER can drive about 2,050 feet (625 meters) on one battery charge. That could fluctuate a bit depending on how much any onboard instruments are used.

Besides desert conditions, PUFFER has been outfitted for snow. Carpenter designed bigger wheels and a flat fishtail to help it traverse wintry terrain. So far, it's been tested at a ski resort in Grand Junction, CO; Big Bear, CA; and on Mt. Erebus, an active volcano in Antarctica.

The PUFFER project, managed by JPL, is part of the Game Changing Development (GCD) program. For more information, visit here.