Tiny bot folds itself, unfolds possibilities

Shape-shifting robots could one day adapt to a variety of tasks.

Shape-shifting robots could one day adapt to a variety of tasks in dynamic settings.

Here’s a little robot that knows how to dress for the occasion. Scientists at MIT have built a bot that can, with a little origami action, change its shape from a walking bot to a rolling or even a gliding one.

The tiny folding machines, described in the journal Science Robotics, could make it easier for future bots to adapt their abilities in dynamic environments, from city streets to the insides of our bodies.

Researchers have been trying to find ways to make lab-built robots more capable in real-world contexts. They’ve made wheeled robots than can go long distances, legged cockroach robots that can crawl through tight spaces, and even snake-like ones that can make their way through hard-to-reach spots for search-and-rescue operations. But these robots aren’t really multitaskers; their form limits what they can do.

“A robot with a fixed body will perform the tasks for which it’s designed well — but perform poorly, if at all, on tasks for which it is not designed,” said study senior author Daniela Rus, a roboticist and director of MIT’s Computer Science and Artificial Intelligence Laboratory.

In fact, that’s why roboticists, such as many of those that competed in the DARPA Robotics Challenge in 2015, focus on humanoid robots: They’re often considered better able to handle a wide range of tasks in human environments. But these robots are really complicated — and two-legged walking is hard to master.

So is it better to have a simple robot or a complex one? Rus and her colleagues may now have found a way around this dilemma.

As the scientists point out in their study, nature is filled with animals that change their shape on command or as part of their life cycle. Hermit crabs choose what shell to wear; caterpillars morph into butterflies. Why couldn’t a robot do the same?

Using an origami-like folding technique that’s previously been used to create all kinds of robots, Rus and her colleagues built a system in which a simple centimeter-scale robot could change its shape when needed. The robot starts out with a “seed” — a tiny cube that hops around a test plate, directed by a magnetic field. It can hop onto a flat sheet that’s actually an exoskeleton, waiting to be activated.

These thin, flexible exoskeletons are made out of two sheets of polyester with a heat-sensitive layer sandwiched between them. Each exoskeleton is cut in a specific design that, when heated, cause the sheet to fold itself into a predetermined shape around the cube.

The first exoskeleton the cube puts on allows it to walk. That little walking bot can then put on an additional exoskeleton to give it another ability — to walk faster, to wheel around, to float like a boat, or even to glide away. More shapes are possible too, Rus added.

“We can design anything our imagination produces,” she said.

It can even take these exoskeletons off by hopping into a shallow pool of water, causing the tabs wrapped around its body to dissolve. So the robot can put on and slough off these simple exoskeletons as needed, depending on the task at hand.

This robot could be useful in a variety of settings, Rus said. She’s previously designed a tiny origami robot that can be swallowed to retrieve small foreign objects — say, a button battery in a child’s stomach, or patch an internal wound. Being able to switch outfits could turn this robot into a mini medical superhero — for example, allowing it to remove objects, collect tissue samples and repair damage in a single operation.

These suit-shifting robots could become handy on large scales too, she added. Engineers could make cars with compact bodies that are easy to parallel park, and create larger exoskeletons with extra trunk space that can be put on to cart groceries or even furniture home.

The next step, she said, will be to scale up the technology, and start looking into these real-world applications.