Technology Lab / Information Technology

Here come the inflate-a-bots: iRobot’s AIR blow-up bot prototypes

DARPA-funded systems are part of quest for cheaper, lighter, more capable bots.

A DARPA-funded research project at Massachusetts-based iRobot has developed a series of prototype robots with inflatable parts. The robots, developed with researchers from Carnegie-Mellon University and inflatable engineering company ILC Dover, are part of the Defense Advanced Research Projects Agency's program to create more mobile, more capable, and less expensive robots for the battlefield.

In an interview with Ars, Chris Jones, director for research advancement at iRobot, said that the Advanced Inflatable Robotics (AIR) research prototypes—which include a modified PackBot with an inflatable manipulator arm and a fully inflatable "hexabot" that walks on six legs—were developed as part of one of several research initiatives at the company funded by DARPA’s Maximum Mobility and Manipulation (M3) Program, an effort launched in March of 2011. The program has resulted in a number of other recent robotics advances, including flexible robots that can change color and the Boston Dynamics land speed record-holding Cheetah bot.

The military has been using small robots from iRobot, such as the PackBot, for years, purchasing hundreds of the bots for dealing with improvised explosive devices and checking out potentially dangerous areas. The M3 program is a broad research initiative to develop technologies that will make small robots even more capable. Inflatable robotic systems are of particular interest because of their decreased weight and because of how cheaply they can be manufactured.

"A lot of what we do is centered around making very capable but small robots," Jones said. For small, untethered robots—whether they're on the battlefield, cleaning your kitchen floor, or helping tend to patients in hospitals, "weight is at a premium," he said, because of its impact on the robot's battery life and mobility. Inflatable parts can drastically reduce the weight of a robot, while still having a comparable level of functionality. The manipulator arm on the current iRobot PackBot, for example, weighs over 15 pounds; the "AIRarm" weighs under half a pound, and can lift as much as five pounds, depending on its level of inflation.

The AIRarm inflatable manipulator in action on a modified iRobot PackBot.

Another plus for inflatable robotics is the amount of space that an uninflated component can be packed into. The AIRarm can be "crammed into a ball" inside the PackBot, Jones said. Since the arm inflates on demand, it's not taking up valuable real estate on the body of the robot that can be used for other sensors or functions—especially since a manipulator arm may not be used that frequently in some cases.

And then there's the "soft touch" capability of inflatables. An inflatable robotic arm can adjust its "compliance," Jones said—it can make the arm more or less rigid, depending on the situation.

"Whenever you're talking about a robot with an arm making contact with its environment—opening doors, touching a person—you have to be sensitive to that contact," he explained. "You need to have a soft touch, but still have some strength. With an inflatable arm, you can change its compliance so you can change the arm's ability to deform. If it's driven into a wall and an arm isn't inflatable, it will drive through the wall or break the arm." But with an inflatable arm, if the pressure in the arm is decreased, it will just buckle or fold over when it hits a wall.

And that variable compliance also allows inflatable arms to reach into places mechanical arms can't reach by following the contours of confined places. "You can imagine an inflatable arm being able to push itself into an opening and follow a wall." Jones said. "And you may have opportunities to inflate and deflate different parts of the arm to get access through a small opening, and then get a large arm on the other side."

In addition to the AIRarm, which IEEE Spectrum’s Automaton blog wrote about after a visit to iRobot, the company has also developed a small prototype robot that is entirely inflatable and walks on six string-actuated legs. While the hexapod was developed purely as a research prototype with no specific application in mind, "there are a wide variety of uses that this technology could be tailored to," Jones said.

Enlarge / An inflatable hexabot prototype developed at iRobot.
DARPA just awarded iRobot an additional $650,000 contract to continue its work on inflatable manipulators under the program. The company also has other initiatives underway that are funded by the M3 program, including the Advanced Suspension for Improved Mobility (ASIM), a stabilized suspension system that makes it easier for small robots to traverse rough terrain and handle debris. Jones said that additional projects were in development for the program, but weren't at a stage where the government would allow him to discuss them.

A demonstration of the ASIM robotic suspension system.


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