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Intelligent Machines

iRobot Roomba

Sure, robots can clear mines. But can they handle dust bunnies?

For years now, whenever Colin Angle told somebody that he’s the CEO of a company that builds robots, he always heard the same joke: “When are you going to build a robot that can clean my floors?” Colin’s riposte was always the same: for ten thousand dollars, they could have their floor-cleaning robot tomorrow. But at that price, few people were interested.

Today those jokes are a thing of the past. On September 23rd Angle’s Somerville, MA company, iRobot, took the wraps off its ambitious three-year project to build that most requested robot-the robot that cleans house. Called Roomba, the robot is a little battery-powered vacuum cleaner that scurries around the floor, sweeping up dust and dirt as it travels. And instead of costing thousands, Roomba costs just $199. “That’s why this is an incredibly important robot,” says Angle.

If anything, Angle is being modest. Although Detroit has been using robots to build cars for four decades, Roomba is the first device to bring the labor-saving promise of robotics into the home. While Sony’s Aibo and similar toys proved that consumers want robots, Roomba may be the first that they actually need.

That’s because Roomba isn’t just for show. It does a fabulous job on the daily chore of sweeping or vacuuming. It picks up dust bunnies, dirt tracked in from the street, spilled rice and coffee grounds, loose beads, and most other objects that are smaller than an acorn. It gently avoids furniture, it doesn’t fall down stairs, and it runs up to 90 minutes on a single battery charge-enough time for it to clean two 16- by 20-foot rooms. This machine is not a gimmick: it gets floors clean.

To use the Roomba, you put it on the floor, turn it on, and press the button marked S, M or L (depending on your room size). The robot plays a little tune and starts sweeping the floor in an ever-widening spiral-essentially, the machine sweeps in crop circles. When it bumps into something, it backs up, turns, and starts off in a new direction. Periodically Roomba alternates this behavior with a wall-and-furniture-hugging algorithm and straight lines across the fall. It will also randomly turn and drive as far as it can until it hits something.

Computer scientists call the Roomba’s behavior a “random walk.” The big advantage of this approach is that the Roomba doesn’t need to map out your living room and then keep track of where it’s been. Roomba’s walk isn’t guaranteed to cover an entire floor, but in practice it does a very good job. The S, M and L buttons adjust the parameters of the walk and determine how long the machine runs before it decides that it is finished.

Being a robot, Roomba doesn’t think like a human being, and it doesn’t clean like one either. I turned it on in my bedroom and the first thing it did was drive underneath the bed, sweeping up an inch of dust that my professional housecleaner had somehow forgotten for more than six months. On the other hand, it’s easy for Roomba to get tangled in power cords, long shoelaces, or even socks. My loaner Roomba sucked up a headband that my daughter had left underneath her bed and stopped working until I turned the machine over and manually extracted the offending garment.

“It’s a hard worker,” says Angle. “You start off thinking that it is very cool, and you let it run. After a few minutes you get tired of watching it and go off and do whatever else you want to do. You can think of it as a helper and you feel good about it.”

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.

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