From a sheet of paper, a robot arises
Scientists unveil a device that builds itself in a technique that might be cheaper than 3D printing.
It’s alive! Using some paper, a circuit board and the plastic used in Shrinky Dinks toys, a team of researchers has designed an origami-inspired crawling robot that folds itself into working order in about four minutes.
These Transformer-like paper bots, described this week in the journal Science, could offer a new way to make lightweight, self-building structures and machines — and give 3D printing a run for its money.
“I thought it was really exciting,” said Michael Dickey, a chemical engineer at North Carolina State University who was not involved in the research. “It’s quite a feat of engineering.”
Even though the paper bot was made from a single sheet of composite material, it folded itself into a shape that could walk and even turn. It easily carried the circuitry and batteries required for it to work, and was able to travel 2.1 inches per second.
The mechanical crawler is made out of a piece of flexible circuit board layered with sheets of polystyrene and paper with fold lines cut into a specific design. When a current is sent through the circuitry board, the resistive circuits heat the polystyrene layer along the fold lines to 212 degrees. The polystyrene — the same material used in Shrinky Dinks — contracts, pulling at the paper layer and causing the joints to fold.
The mathematics of origami folding has long impressed scientists. And folding is a technique used by living things on many levels, whether it’s the folding of proteins on the cellular scale or the folding of tissue in the brain.
For engineers, it can be a way to maximize surface area or strength or both with very little material. Another report in the same issue of Science led by Jesse Silverberg of Cornell University altered the stiffness of an origami-folded object by squashing one or more of the folds.
Scientists have tried building by folding before. In fact, a Harvard University team built the world’s tiniest flying robot, nicknamed RoboBee, last year by using origami-like folding techniques.
But for this project, another team of researchers also anchored by Harvard engineer Robert Wood wanted to see if it could make a complex machine that could assemble itself.
“We picked a crawling robot because it’s actually a very difficult problem,” study leader and Harvard roboticist Sam Felton said. A stationary machine, with a heavy, boring base, would have been much easier to fold into position — and then it would stay put. But for a crawling robot, “we had to make sure we could fit all the power and the controls in a mobile structure.”
This method for building machines — creating two-dimensional patterns that fold themselves into complex three-dimensional shapes — could be cheaper than 3D printing, Felton said.
The materials used to make it didn’t cost much: The paper was akin to very thin poster board, and the polystyrene cost about 50 cents a sheet.
Origami-inspired assembly could make machines potentially easier to mass produce, and it’s simpler to install chips and batteries on a flat surface than around or inside a complex, 3Dprinted object.
Such self-folding machines could one day be used as satellites. They could be sent into space in an easily packed stack of sheets, then unfold themselves into their proper shapes once they reach orbit. They could land on another planet and quickly assemble into a shelter.
On Earth, they could be tossed into disaster zones to enter earthquake-ravaged buildings, or perform other work in areas that are unsafe for humans.
There are many steps to be taken before that can happen, Felton pointed out. For one thing, scientists need to develop software that will come up with the complex fold pattern for a robot or machine. For this robot, Felton had to do much of the patterning by hand.
“I tried using some programs, but a lot of it came down to trial and error,” he said.
The technology is in its infancy. Future robots may need different materials that are stronger or more versatile. And for now, the assembly is a one-way process: Once a robot has folded, it can’t unfold itself back into a flat sheet.
But researchers are working on building tiny pouch motors that could fold and unfold at will, Felton said. And with those kinds of joints, this origami technique could one day lead to robots that could, like the fictional Transformers robots, change into different configurations, depending on the situation.