How Squishy Would You Like Your Robot?

Phase-changing structures bring on-demand squishiness to robots

2 min read
How Squishy Would You Like Your Robot?
Photo: Hosoi Group/MIT

Most robots are rigid. Rigid is easy to design, easy to construct, easy to calibrate, and more reliable for all of those dull, dirty, and dangerous tasks that robots excel at. When robots make fundamental structural compromises to rigidity, they do it in complicated ways, like with series elastic actuators or hydraulics. It's worth it, though, because adding squishiness can make robots both more capable and safer to be around through passive compliance.

Taking this concept to the extreme has resulted in some incredibly squishy robots, including soft robots that can walk, and other soft robots that can roll. But in both of these cases, embracing squishy properties means giving up rigidity. MIT has been working on a structure for a robot that offers both: squishy when you want it, and rigidity when you don't.

The MIT approach (which we like to call on-demand squishiness) involves taking a material or structure that's inherently soft and modifying it with another material that can phase change between hard and soft states. In this case, MIT is using a scaffold made of foam that's been coated with wax. Wax, being wax, transitions between solid and liquid at a relatively low temperature. When the wax is cold and solid, the foam structure is rigid, but if the wax is heated to soften it, the entire foam structure becomes soft as well.

The researchers also demonstrated that by selectively deforming parts of a structure, they could create joints and make the structure move using a cable (as seen in the video). We're guessing that as a next step several of these deformable structures could be combined to create a robot that can crawl and squeeze into tight spaces.

And wax is one of the easier and safer materials to use for this purpose, although there are many other options, like liquid metals or magnetorheological or electrorheological fluids, which respond to magnetic and electrical fields.

The project began as a collaboration with Boston Dynamics, as part of DARPA's ChemBot program (which led to some really cool and weird soft robots, like this and this). The MIT researchers, led by Anette Hosoi, a professor of mechanical engineering and applied mathematics, have since teamed up with the Max Planck Institute for Dynamics and Self-Organization and Stony Brook University to continue developing versatile, deformable robots.

The researchers say that robots like these would be ideal for search and rescue scenarios, where you'd need a lot of compliance and flexibility for crawling around and through jumbled piles of rubble. They also suggest that robots like these would be great for crawling around inside your body, where they'd be able to "reach a particular point without damaging any of the organs or vessels along the way." Thanks for that, we squishy humans definitely appreciate it!

Via [ MIT ]

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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

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

"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.

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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