Origami Robot Folds Itself Up, Does Cool Stuff, Dissolves Into Nothing

Tiny self-folding magnetically actuated robot creates itself when you want it, disappears when you don't

3 min read
Origami Robot Folds Itself Up, Does Cool Stuff, Dissolves Into Nothing
Photo: Evan Ackerman/IEEE Spectrum

At ICRA 2015 in Seattle yesterday, researchers from MIT demonstrated an untethered miniature origami robot that self-folds, walks, swims, and degrades. That’s the title of their paper, in fact, and they delivered on all of those promises: from a flat sheet with a magnet on it, their robot folds itself up in just a few seconds, is immediately ready to zip around on land or water driven by magnetic fields, and then when you’ve run out of things to do with it, drive it into a tank of acetone and it’ll dissolve. This is the first time that a robot has been able to demonstrate a complete life cycle like this, and eventually, it’ll be doing it inside your body.

The unfolded robot, which is made of a magnet and PVC sandwiched between laser-cut structural layers (polystyrene or paper), weighs just 0.31 g and measures 1.7 cm on a side. Once placed on a heating element, the PVC contracts, and where the structural layers have been cut, it creates folds.

img The origami robot and the actuation methods. (a) Outlook of the system. (b) The crease pattern. (c) Walking mode by torque-based control. (d) Swimming mode by force-based control. Image: MIT

In under a minute, the robot is finished, and is ready to go, zipping around at speeds of between 3 and 4 cm/s.

img The electromagnetic coil system that drives the robot. Image: MIT

A caveat to all of this is that the “motor” of the robot isn’t really integrated into the whole self-folding and dissolving thing. The motor comes in two parts: a cubic neodymium permanent magnet that the robot folds itself around, and then a set of four electromagnetic coils underneath the surface that the robot operates on to provide the magnetic fields that drive it [right].

You might be wondering at this point why the folding robot is even necessary if you’ve got a magnetic field and you can just drag the magnet around with that, and there’s a good answer. First, the magnetic field isn’t dragging the magnet anywhere: the field is directional, but it’s just turning on and off at about 15 Hz. This causes the magnet that the robot is attached to oscillate back and forth, and the robot oscillates as well. As this happens, the front and back legs of the robot alternately contact the ground, and the asymmetry of the design combined with the intentionally off-center balance point causes the robot to walk forward. None of this works with the robot in its unfolded, flat configuration: it has to be folded into this shape to walk at all.

The other advantages of using a folded robot instead of just a magnet include the ability to float, as well as the ability to more efficiently perform tasks like moving objects or digging. And this isn’t the only design that you can use, of course: you can optimize for whatever task you’re trying to accomplish. This particular one is more of a generalist. If you want to get really fancy, you could also make the folding process multi-stage: low heat gets you one design, and then coming back to the heating pad and turning up the heat could result in a second folding stage resulting in a different design.

Once you’re done messing around, you can drive the robot into a tank of acetone and it will entirely dissolve (except for the magnet). It’s also possible to make the structural layer of the robot out of a material that dissolves in water. Making the entire robot dissolve in water is a bit trickier, but the researchers seem confident that it’ll be possible in the near future. Also possible in the near future will be integrating self-folding sensors into the body of the robot, which could lead to autonomous operation, and eventually, doing all of this inside your body.

“An Untethered Miniature Origami Robot That Self-folds, Walks, Swims, and Degrades,” by Shuhei Miyashita, Steven Guitron, Marvin Ludersdorfer, Cynthia R. Sung, and Daniela Rus from MIT and TU Munich, was presented yesterday at ICRA 2015 in Seattle.

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Robot with threads near a fallen branch

RoMan, the Army Research Laboratory's robotic manipulator, considers the best way to grasp and move a tree branch at the Adelphi Laboratory Center, in Maryland.

Evan Ackerman
LightGreen

“I should probably not be standing this close," I think to myself, as the robot slowly approaches a large tree branch on the floor in front of me. It's not the size of the branch that makes me nervous—it's that the robot is operating autonomously, and that while I know what it's supposed to do, I'm not entirely sure what it will do. If everything works the way the roboticists at the U.S. Army Research Laboratory (ARL) in Adelphi, Md., expect, the robot will identify the branch, grasp it, and drag it out of the way. These folks know what they're doing, but I've spent enough time around robots that I take a small step backwards anyway.

This article is part of our special report on AI, “The Great AI Reckoning.”

The robot, named RoMan, for Robotic Manipulator, is about the size of a large lawn mower, with a tracked base that helps it handle most kinds of terrain. At the front, it has a squat torso equipped with cameras and depth sensors, as well as a pair of arms that were harvested from a prototype disaster-response robot originally developed at NASA's Jet Propulsion Laboratory for a DARPA robotics competition. RoMan's job today is roadway clearing, a multistep task that ARL wants the robot to complete as autonomously as possible. Instead of instructing the robot to grasp specific objects in specific ways and move them to specific places, the operators tell RoMan to "go clear a path." It's then up to the robot to make all the decisions necessary to achieve that objective.

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