Return of the Roomba!

Yay! My roomba is alive again!! Well, mostly alive. Alive enough.

My poor Roomba 570 has had mad cow for a couple months now. I poke the “Clean!” button and it moves a few inches, spins around, backs up a little, spins around some more and just keeps doing that, over and over, for a few minutes before beeping at me then shutting itself off. Stoopid thing.

Hey!! Before you read any more, note that iRobot, the folks that make Roombas, will likely become angry if you fiddle with the machine. If your warranty isn’t dead yet, don’t be doing this stuff!

The iRobot web site suggests blowing the bottom of the machine out with some canned air and cleaning it up. This makes sense – if you’ve got gunk (mostly likely stray bits of ABS in my place) blocking a sensor or getting a wheel stuck, the machine isn’t going to be happy.

I picked up a couple cans of air at BestBuy and blasted every nook and craney I could find. The bot started working again, yay!!, but then regressed and started doing the mad cow thing again after about 15 minutes. 😦

Next was to pull the bottom off the bot and do more cleaning. Long story short, it was good for about 15 minutes again, yay! again, then started losing it. 😦 again.

I tried iRobot support but they weren’t horribly useful. The ‘bot is about 14 months old, which puts it out of (12-month) warranty and the only thing iRobot would do was ask for my phone number and a time that was convenient to talk about me buying a new one. Sorry guys but I’m not interested in having to drop $500 a year to have a reliable vacuum cleaner. Yes, it’s incredibly cool & useful when it works but, well, $500. 14 months. It’s not THAT cool.

A little googling led me to “Avi’s page for iRobot Roomba 5xx bumper IR fix“, which tells you how to diagnose problems like this and how to fix them, if your bumper is toast. (Thanks, Avi!!!)

Key to figuring out the problem is putting the roomba in diags mode, which is very, very helpful. To paraphrase Avi a bit, the routine is:

1. Make sure the bot is off. If the Clean LED is on, hold down both Spot and Dock for 10 seconds to turn the bot off
2. Hold down both Dock and Clean and, while holding them down, press Spot 6 times then release Dock & Clean
3. You’re now in diagnostics mode
4. Press Dock twice to get into test #2, the bumper test mode. It will beep once on the first press and twice on the second press
5. In test #2, the Spot button will light up when the left bumper is pressed, the Dock button will light up with the right bumper is pressed and both buttons will light up when the front of the bumper is pressed
6. Mess around with pressing the bumpers and watching these lights. Take notes
7. Press and hold both Dock and Spot for 10 seconds to exit diagnostics and turn the bot off

In my case, the Dock button was always lit up – the right bumper sensor was stuck on. The Spot light would respond nicely to presses of the left bumper but Dock was always on.

A little more quality time with google and I found a new bumper sensor board at the RobotShop for only $18. Hm.. $18.. $500.. Yay! They’ve got a number of replacement bits for Roomba’s or you can even send the whole thing to their Robot Hospital and they’ll fix it up for you. Good stuff, shipped quick, works as advertised. Thumbs up.

If you’ve built a MakerBot, Mendel or similar machine, disecting a Roomba and replacing this sensor is well within your skill set. I’m not going to go into all that – it’s about a bazillion little screws and takes a while – but Avi does on his page. Avi describes fixing the actual little tiny bits (IR emitter) but the part from the RobotShop is just a complete little PBC with the IR stuff already on it. You can save a bit of cash by just replacing the broken bit on the board or you can do the RobotShop deal and just get a whole new one for $18, like I did.

The bot still has problems detecting head-on collisions. It turns out there is no ‘center’ bumper – it takes both the left & right sides activating to mean it’s hit something head on. I think this is probably my not assembling it totally correctly though instead of something electronic. It’s not a big deal as it eventually figures things out, turns and carries on vacuuming my place again.

All in all, I’m happy. $18 (+ shipping) and a little work isn’t too bad to get somebody to vacuum my whole place again, every day.