Robot Uses Supersonic Jets of Air to Stick to Almost Anything

By blowing air across a surface really, really fast, this robot can suck onto everything from metal to bricks to cloth

2 min read
Robot Uses Supersonic Jets of Air to Stick to Almost Anything

There are all kinds of ways to stick to a surface, but one of the simplest is to use a gripper that operates on the Bernoulli principle. All the Bernoulli principle says is that as a liquid moves faster, its pressure decreases. For the purpose of a robotic gripper, air counts as a fluid, and if you squirt air out around the edges of a circular gripper fast enough, it'll start to generate a vacuum force that's strong enough to grab things without the surface of the gripper actually needing to touch them. The major upside of this technique is that you get a non-contact vacuum grip, so it's useful for grabbing stuff that's sterile or fragile.

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Image: Bosch Rexroth AG

While Bernoulli grippers are fine for picking up things, they're not generally strong enough to enable a robot to support its own weight, much less climb. A research group from the University of Canterbury in New Zealand has developed a supersonic version of the Bernoulli gripper that's five times stronger than the conventional version, which is enough to allow a robot to climb on a bunch of different surfaces. And when you're watching this video, keep in mind that unlike pretty much every other climbing robot in existence, the grippers on this robot aren't touching the wall:

The geometry of the new type of air gripper (or non-contact adhesive pad, abbreviated NCAP) that this robot uses has been carefully designed to use a tiny little gap (a mere 25 μm in size) to force the airflow to go supersonic. Or more precisely, Mach 3. This doesn't require an increase in airflow or in pressure, it's all done with the geometry of the gripper itself compressing the airflow and speeding it up:

This airflow creates a low pressure vortex inside the gripper which provides the actual adhesion force, and in testing on the robot, this supersonic gripper is able to support five times as much weight as a conventional Bernoulli gripper, all without using any additional air volume or pressure.

As for the robot itself, it may be used for industrial inspections. The supersonic non-contact grippers will be available in "some months" for "a few hundred dollars," the researchers say.

The robot was presented in an ICRA paper entitled "An Investigation into Improved Non-Contact Adhesion Mechanism Suitable for Wall Climbing Robotic Applications," authored by Matthew Journee, XiaoQi Chen, James Robertson, Mark Jermy, and Mathieu Sellier.

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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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