The Rug Warrior. (mobile robots) (Column)
by Steven Anzovin

In Czech playwright Karel Capek's 1922 satire R.U.R. (the work in which Capek coined the term robot and invented many of the other ideas about robots that we take for granted today), a young, idealistic woman visits a company that builds human-like artificial workers.

"What sort of worker do you think is the best from a practical point of view?" a company executive asks her.

"The one who is most honest and hardworking?" she guesses.

"No," says the executive, "the one that is cheapest. Young Rossum [the robots' inventor] rejected everything that makes man more expensive. In fact, he rejected man and made the Robot. Mechanically they are more perfect than we are, they have an enormously developed intelligence, but they have no souls." But later it turns out that the robots do have souls, and in anger over being exploited they rise up and destroy their masters.

The fear of vengeful robots has been around since well before the Terminator movies or even Mary Shelley's Frankenstein. In Jewish folklore, an artificial man called a golem protected the Jews of sixteenth-century Prague, but he had to be destroyed when he could no longer be controlled.

For all our anxiety about robots, in the real world they aren't at all like us, nor are they ready to rebel against their creators. Given the current level of robot research, that future, if it ever comes, is comfortably far away. But if you're a handy hardware hacker, you can do mobile robot research at home--and possibly bring that future a step closer.

One source to check out is the book Mobile Robots: Inspiration to Implementation by Anita Flynn and Joseph Jones (Jones & Bartlett Publishers, 1 Exeter Plaza, Boston, Massachusetts 02116; 800-832-0034; $29.95; slated for a fall 1992 release). It contains complete instructions for creating an autonomous mobile robot from parts costing about $200, all of which can be purchased at your local Radio Shack and electrical supply store. For readers less familiar with a soldering iron, the authors plan to offer both a kit and a fully assembled 'bot. The little beast, called the Rug Warrior, will zip around obstructions, tag after you as you move around the room, and come when you call.

I talked with coauthor Joseph Jones, who works at Artificial Creatures, a division of Intelligent Systems Robotics (238 Broadway, Cambridge, Massachusetts 02139; 617-876-2999). He described some of the issues involved in making robots truly autonomous and mobile. Interestingly, the problems aren't so much mechanical as conceptual.

Most autonomous mobile robots work by comparing the current environment as perceived by the robot's sensors with a software-based "world model" contained in its controlling computer. The more complete and detailed the rules contained in the world model are, the more autonomy the robot can achieve, but checking every movement against the rules requires lots of processing power and slows the robot down. It's as if you had to think about the global consequences of every step whenever you walked around the house. Jones, however, is working with a different model of robot autonomy called subsumptive behavior, which was developed at Rod Brooks's Mobot Lab at MIT. Mobile robots using subsumptive behavior don't follow a world model at all; instead, each sensor directly triggers a behavior.

Jones believes that building such reflex behaviors into robots is the way to create responsive mobile 'bots capable of practical tasks. What's the one innovation that Jones thinks will bring us into the Robotic Age? "There are plenty of problems to work on," he chuckles, "but I've got a little kid, and a robot that could clean up under the kitchen table would make a big difference."

Another useful resource is The Robot Builder's Bonanza by Gordon McComb (TAB Books, 13311 Monterey Avenue, Blue Ridge Summit, Pennsylvania 17294; 717-794-2191; $14.95). This book includes tips on choosing motors, building power supplies, constructing metal and plastic bodies, and designing locomotion and arm systems.

Bear in mind that one day our mechanical creations might refuse to clean up after us and head out the door to join others of their kind. Let's hope they think well of us.