Robot vacuum cleaners have been around for quite a while now and a number of companies have given them a go. However, just as Hoover has come to be an everyday word for a regular vacuum cleaner, there's one company that has managed to become synonymous with robot vacuum cleaners and that company is iRobot. Or more specifically that product is the Roomba.
Now in its third generation, the Roomba is available in four models, the 581, 563, 555 and 520, which are differentiated by former's ability to be scheduled and that the latter comes with no Virtual Walls. The Virtual Wall lighthouses emit an infra red beam and are used to electromagnetically cordon off the area you'd like the Roomba to work within. All three Roombas can apparently clean up to four rooms on a single charge and will return to their docking stations when finished or low on battery. We're looking at the 520 model today.
Compared to the Samsung Navibot SR8855 the Roomba 520 seems much more petite. At 340 x 340 x 90mm it's actually only 15mm shorter and 10mm narrower, but it certainly looks considerably smaller. It's also more sensibly decorated with just a matt creamy white finish to most of the body and a matt silver top. This means it should hide most scratches and grime better than the shiny plastic of the Navibot. It also has a rather neat extra, that being a handle that's incorporated into the top.
Overall build quality also seems decent with two strong, deeply sprung rubber wheels propelling the Roomba along, a sturdy looking cleaning mechanism and generally tough plastics used throughout. That said, aside from its shiny plastic, the Samsung Navibot did seem to be a step up with a hefty rubber section running round the bot's edge, more substantial rotor brushes (not to mention the Samsung also has two of these), and a more sophisticated main brush. Also the Roomba's docking station feels distinctly flimsy – not ideal for something that's going to spend its time sat on a floor.
The fact the Roomba only has one brush is a clue to the major difference between it and the Samsung Navibot, and indeed many of these other robot vacuum cleaners. You see, the Roomba doesn't map out its course round a room but merely obeys a few simple rules that by hook or by crook means it should cover the whole area of a floor. Where the rotor comes in is that one of the Roomba's rules is wall following. Using its front and side mounted sensors the Roomba will track along any walls or obstacles that it encounters to ensure its rotor can get right into the corner and prize out all the dirt.
The other rules are spiralling, room crossing and dirt detection. The first of these, as it suggests, makes the Roomba move in an ever expanding spiral until it hits something. This is its main technique for covering large areas. Room crossing then makes the Roomba criss cross the room to ensure it covers the whole room. Finally, dirt detection will cause the Roomba to stop whatever else it was doing and spiral round an area it thinks is dirty (e.g. Paris Hilton - ed).