Robots that keep going and going

ASEE Prism, Mar 2003

The potential for mobile robots is huge. They can help scope out disaster areas too dangerous for humans to tread.They can be built for domestic applications, like butlers.They can be useful in manufacturing processes. But that potential won't be realized until robots have a better power supply-one that lasts. Today's state-of-the-art robots, powered by a combination of a lithium battery and a DC electric motor, poop out after only 15 to 25 minutes. Not a lot of commercial appeal there.

But two researchers at Vanderbilt University are developing a rocket-powered actuator for mobile robots.The device not only weighs much less than batteries, but can repeatedly lift a 51 pound load five times longer than the most efficient batteries or motors. It runs on about 1 gallon of liquid hydrogen peroxide mixed with iridium, a precious metal that acts as a catalyst. This is nearly pure hydrogen peroxide, not the 3 percent stuff the drug store sells, notes Michael Goldfarb, who is overseeing the project with Eric J. Barth.The pair are co-directors of Vanderbilt's Center for Intelligent Mechatronics. Eventually, using that same amount of fuel, a human-size robot could be powered for up to 8 hours, Barth says, which is more like a human work schedule, minus the coffee and lunch breaks. Barth admits there's some risk to having hydrogen peroxide in a pressurized tank, but no more than having gasoline in a car tank."That's something that society has managed to deal with fairly safely," he says. Moreover, he adds, batteries aren't exactly risk-free, either."The contents of the leadacid battery in your car are pretty nasty, but packaged correctly, they are not a major safety concern."

The Department of Defense funds the actuator research and eventually wants to develop robotic exoskeletons to boost soldiers' strength. Exoskeletons could help a soldier carry, say, a 160-pound load because it would only feel like 10 or 20 pounds. So, in theory, tomorrow's infantry soldier may be jet-propelled.