How Robotic Vacuums Work -- B
Inside a Roomba
The Roomba Red is approximately 13 inches (33 cm) in diameter and 3.5 inches (9 cm) tall. An external examination reveals the following parts:
Roombas run on a rechargeable NiMH battery. The Roomba Red battery pack is rated at 3 amp-hours and takes about seven hours to fully charge to about 18 volts. Some of the more recent Roomba models have cut that charge time down to about three hours. A full charge equals approximately two hours of cleaning time, which in the Roomba world means vacuuming three medium-size rooms before it needs to rejuice. The mobility system consists primarily of two motor-driven, tracked wheels. Roomba steers by alternating the power supplied to each wheel.
Roomba has a total of five motors:
One driving each wheel (2 total)
One driving the vacuum
One driving the spinning side brush
One driving the agitator assembly
In the following sections, we'll address each of the systems that make Roomba work, beginning with the most robotically interesting one: the navigation system.
German companies Vorwerk and Infineon have teamed up to produce a prototype carpet that works in tandem with a robotic vacuum. The underside of the carpet is embedded with RFID tags, and the vacuum is equipped with an RFID reader and a digital map of the carpet's RFID locations. The tags direct the vacuum around the room for complete coverage and can tell it to reclean a specific area if it didn't spend enough time there. See Discovery Channel: Intelligent Carpet Directs Robot Vacuum to learn more.