iRobot Roomba

Continued from page 1

By Simson Garfinkel

October 9, 2002

Roomba comes with a single Nickel-metal-hydride battery, an "overnight charger," and an "invisible wall" that shoots out an infrared beam, should you need to keep the robot confined to a particular area. iRobot plans to sell a fast charger, extra walls, additional batteries, and replacement parts as options. It doesn't take vacuum bags-instead, there is a little dirt tray that you need to empty after each use. iRobot justifies the small tray on technical grounds: its small size means that Roomba doesn't need to spend extra energy hauling around dirt. But I think that it's really a stroke of marketing genius: each time Roomba finishes cleaning a room, you get to see how much dirt it actually picked up-truly an education!

A lot of technology goes into this little robot. Each wheel is controlled by a tiny motor with a belt drive and a planetary gear, an integrated optical motion encoder, and a slip clutch-all housed within the wheel itself. Roomba has three separate systems to prevent it from accidentally falling down stairs. Along the robots edge are infrared "cliff sensors" that detect a sudden drop-off. If one of those sensors fails to trigger and a wheel goes over the edge, the robot will detect the sudden change in current to that wheel's motor and quickly reverse direction. Finally, if the first two sensors fail, and Roomba starts sliding into the abyss, ten anti-skid plates on the bottom grip the floor and halt the slide. Even so, the robot is designed to survive multiple three-foot drops onto a concrete floor-"although we would prefer it if you wouldn't do that," I was told.

Much of the technology inside Roomba got its start with other iRobot projects. The "crop-circle" algorithm for floor cleaning, for instance, was first developed for a robot designed to clear minefields. The treads are reminiscent of those on the company's Urban Robot and Packbot. Many of the brush, cleaning, and vacuum ideas were originally developed for an industrial cleaner that iRobot created with Johnson Controls.

For all of my excitement about the Roomba, I did encounter some minor problems. Roomba shuts itself down when an object gets wrapped around its main roller, but it leaves it to you to guess what happened. I would like a better battery indicator. And in a few years time, I would like a machine that can automatically wake up when I am out of the house, clean the floors, and then plug itself in for a recharge.

Despite these minor failings, Roomba is truly impressive. It really does clean your floors! But even more impressive is the robot's price. I showed my loaner Roomba to several friends and asked them how much they thought it should cost. One person said $800. Another said $600. If Roombas are in tight supply this fall, it's a sure bet that they will be showing up on eBay at those prices. But at its breakthrough price of $200, the Roomba really will take service robots out of the realm of science fiction and bring them into people's homes and offices. This little robot is going to have a huge impact.