Testing the new Roomba (as a LEGO battle platform)


My kids are growing up with real robots in the house, from Dad’s UAVs to Roomba. And being 21st Century natives, they think nothing of it–of course the vacuum cleaner is autonomous.

But I thought our first Roomba was a revelation: it was cheap, cool and remarkably effective, although not quite as the designers intended. Roomba got the playroom clean not with its own tepid sucking power but because we told the kids that if they didn’t pick up their Lego, "Roomba will eat it". Over time, however, Roomba got too feeble for regular use and my wife got tired up vacuuming around it (ironic!), and so it was sent to live under the laundry room sink.

Then, last month, iRobot sent over a pre-release version of the new Roomba 560, and we had to pull out the battered older version for a proper head-to-head test. Plenty of other people have already written about the new Roomba’s features, including its stronger vacuum and better sensors. But we wanted to test it for what we actually use it for: Lego jousting. Placing a minifig on a Roombas and watching how long they can stay on as the bot bounces off walls is great fun, and with two Roombas we could compete against more than the clock. A game of rock-paper-scissors decided who was going to get the new Roomba, and as you can see from the princess-on-a-pony figure at right, one of the girls won.

We expected the new Roomba would win the jousting match, because its sensors see approaching walls and slow the bot down for a soft bounce, which tends not to dislodge the Lego figures. But in fact the old Roomba won, two rounds to one. Why? It turns out that front impact doesn’t dislodge the figures, because both Roombas have a depression in the front that the minifigs got lodged in. It’s side impact that sends the minifigs flying, since there’s nothing to stop their slides. Side impact comes from Roomba-on-Roomba collisions.  And there the old Roomba, which doesn’t slow down before hitting things, has the advantage as a battering ram.

Oh, and the carpets? Never been cleaner!

BTW, the new Roomba does seem to do a better job of vacuuming, although it’s still no Dyson. But we had the same problem with it that we had with the earlier one: due to our sofas being exactly the wrong height, the Roombas tend to get wedged under them and shut down. We’ve yet to have one finish a run and trundle back to its charger without help.

But as it happened I was at iRobot (Roomba’s maker) in Boston last week, and they encouraged me to try a little mod. My kids and I drilled holes on each side of the bumper and put a screw in, sticking out by about a half-inch, as shown. This worked perfectly, and now when the Roomba is moving along the side of the sofa, the screws keep it from sidling under and getting stuck. (If our sofas were more scratch prone, we might use something softer than a screw). Here’s the mod:


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