Cleaning Robots

We tested three cleaning robots, priced from $92.99 to $349.99, in the test kitchen and our homes. Two of the three, a vacuum and a scrubber, are made by iRobot, which launched its first vacuum robot in 2002 and has since sold more than 2.5 million units (it also makes robots that clean gutters and pools, U.S. military robots, and ocean-exploring research robots); the third, another vacuum, is produced by P3 International, a manufacturer of consumer gadgets. Both in the test kitchen and at home.

In the kitchen, we gave the vacuum robots a concoction of common kitchen messes to tackle, scattering a measured amount of flour, salt, coffee grounds, minced vegetables, and garlic peels over a 3-foot square of kitchen floor. Looking like oversize Frisbees, the battery-powered robots—all between 13 and 14 inches in diameter and just under 4 inches high—set to work. One of the contenders seemed to push debris around as it cleaned, but our winner picked up almost everything it rolled over.

In the end, our two favorites removed virtually all the debris we put down, but our winner was much more efficient than our second favorite. Furthermore, our second place finisher proved ineffective at picking up one of the very things you’d want it to clean off your kitchen floor—flour—leaving a large smear behind even after repeated passes. (Our winner swiftly sucked up the flour left behind.) When we flipped the two machines over, we discovered why. The vacuum intake on our loser was only 3 inches long and 1 inch wide, compared with the winner, which was 6 inches by 3 inches, similar to that of a conventional vacuum. And whereas our loser has only one small brush that extends from the side to push debris toward the intake, the winner has a side brush plus two counterrotating bristle and beater brushes that work together to shovel up debris.

Next we unleashed the iRobot scrubbing robot, the Scooba, on a sticky blend of corn syrup, oil, and orange juice that we drizzled over flour. We filled the Scooba’s tank with 1½ ounces of cleaning solution ($5.99 for 32 ounces, enough for 21 uses) and topped it off with warm tap water (you can substitute white vinegar for the cleaning solution or use only water if you need just a quick swipe rather than a thorough cleaning). The Scooba first vacuums lightly, sprays cleaning solution, scrubs, and then vacuums up the dirty solution. After a few passes, the floor was spotless.

It was when we took the robots home for “real world” cleaning that the performance of our winners really won us over. (Our winner was described as “life-changing” by one tester, and more than one of us threatened to keep it and its scrubbing sibling.) One home had two cats, another a dog; floor surfaces included hardwood, linoleum, area rugs, and wall-to-wall carpets. Here, we noticed differences in the way the robots maneuvered. All three zoomed around the floor, gently bumping into obstacles and switching directions, and all cleaned under items that were at least 4 inches off the floor. But when they got into tight spaces, the our winning models easily worked themselves free by spinning in place, while the loser, which pivots on one of its rear wheels, sometimes struggled.

Both vacuum robots got stuck at one point, but whereas our winner had an audible “error” tone that alerted us, the loser simply shut off. In operation, our winner was quieter and didn’t disturb the dog; the loser was too loud for our canine companion. Both vacuums maneuvered over power cords and went from hard floors to area rugs and carpet effortlessly. All traveled right to the edge of stairs without taking a tumble. Our winner's waste bins were easy to remove and empty, the loser's slightly more complicated.

A lot of technology went into these little guys. Multiple sensors of different types pick up on environmental data and transmit it to a microprocessor, which adjusts the robot’s actions accordingly. An infrared sensor, for example, sends out a signal that the robot expects to immediately come back as it bounces off the floor; if the signal doesn’t return, the robot knows there is a drop-off and will steer clear. One model uses infrared sensors to avoid rugs and carpets, and all the models rely on them to travel along the perimeter of a room, skirting the walls as they clean. When they hit an obstacle with their bumper, the bumper retracts, activating a sensor that warns them of the obstacle and instructs them to change direction. 

Inner Mechanisms

Our winning vacuum has two additional sensors: an infrared one that helps it find its recharging dock, and an acoustic impact sensor, which helps it clean more efficiently. Located on the underside of the machine, directly behind the brushes, it is constantly pelted with dirt as the robot moves along the floor. When our winning vacuum passes over a particularly soiled area, this sensor detects the increased vibrations caused by the dirt and directs the robot to pass over the area multiple times.

Our testing pointed up clear differences in navigation and maneuvering among the three models. Our winning vaccuum we found, has a better processing system than the loser, enabling it to respond and move more quickly and to direct its power more precisely.

Our winners may be expensive, but they’re also sophisticated and tireless cleaning machines. They may miss the occasional spot—but then again, so might you.