Roomba Anatomy (part 3 of 4)

I won't repeat stuff that's been covered in the last few posts; so if something doesn't seem to make sense here, please look at the last couple days' entries to understand unfamiliar terms. etc.

So, without further ado, I present you, dear readers, this brief tour of Roomba's anatomy.

OK, OK.

Here's the non-Vitruvian view. (As always, click for larger versions):


In the above photo, you're looking straight down at the little beast. Its normal forward direction of motion would be towards the top of the photo. The large semicircular leading edge (also towards the top of the photo) is the contact bumper. Four IR photoeyes built into and behind the contact bumper shine ahead and to the sides of the Roomba's forward motion to detect obstacles.

In the middle of the bumper, at the 12-o'clock position in this photo, you can see a round protuberance. This is a separate IR detector that the Roomba uses to find the recharging "Home Base" and to navigate by "lighthouses."

The smaller semicircle inset from the edge of the device (again, towards the top of this photo) is a folding carrying handle. The beastie weight maybe 5-6 lbs (call it 2.5 kilos), so it's easy to carry around or over stairs.

Here's a closeup of the central control panel:


Normally, you just press the center "Clean" button, and Roomba does its thing. But it also has a built-in clock (including day of the week), so you can automate your cleaning and have the robot fire up on its own at set times on given days. It can be somewhat amusing the first time it fires up when you're not expecting it. ([1] Roomba starts. [2] Human brainstem generates primitive message: WHAT THE HELL WAS THAT?!)

Ahem.

The "Dock" button lets you manually instruct Roomba to scurry back to the recharging base, if you want or need it to, although it will do so automatically if the battery runs low or if when it's finished cleaning.

The "Spot" button starts Roomba in it spiraling cleaning mode, if you want it to pick up a specific spill or concentrate in an area.

If you're using the Home Base to dock the Roomba, it recharges itself. But you also can use a standard plug-in recharger, which goes here. All the Roombas come with a standard recharger; only some come with the "Home Base" gizmo (mine did):

This model Roomba recharges in no more than 3 hours (usually a lot less). A full charge runs it for about 90 minutes, or three average rooms' worth of cleaning. It runs down faster on rugs and carpets (more friction for the brushes). I haven't had any problem with run times being inadequate for the job.

The onboard brain tracks battery use and will periodically do a "deep recharge" when it thinks the battery needs reconditioning. That's never happened with my unit, so far. It also tracks battery temperature, and won't recharge if the battery's too warm. That too has never happened with mine.

Flipping the Roomba over reveals the working parts. I'll show them to you in a moment, but I have to say that when I first saw the bottom, I was pleasantly surprised in an unexpected way.

Let me explain: You see, as a computer guy, I've been waiting for younger engineers to affect PC design; not the outer cases and cosmetics, but the way PCs are physically assembled.

It's obvious that the first PCs were built by guys who had played with Erector Sets as kids. The PCs they designed went together with nuts and bolts and stamped steel parts: mechanical assembly techniques and philosophies that those engineers were totally comfortable with, having played with them as kids. They took the ideas and even aesthetics of what looked "right" to them at a subconscious level and applied them to the very grown-up things (PCs) they were (and still are) designing as adult engineers.

But the children those engineers had--- the next generation--- didn't play with Erector Sets. They grew up with snap-together Legos and brightly-colored Fisher-Price toys. I've always wondered why Lego-style, Fisher-Price-style ideas and the mechanical aesthetics had never really shown up in PCs.

But when I turned the Roomba over, I knew that at least some of those kids had grown up to be robotics designers:



That's not to say Roomba is a toy any more than a PC is a toy. (OK, they both can be toys, but you know what I mean.) Roomba design is clearly an industrial vision from a post-Erector Set mind. I think that's kind of cool.

Below: A closer view of the beater bar, main brush, star-shaped side brush, driving wheels, and debris bin (with the yellow vacuum filter visible inside).


The entire device is extremely modular (http://tinyurl.com/cmcrsd) --- another hallmark of Lego-influenced minds at work.

Below: the star-shaped side brush. It's very flexible, so it can get into corners and into the wall/floor intersections. In this view, it would spin clockwise, sweeping debris into the path of the main brush.



The Roomba is a tricycle design with two powered rear wheels and an unpowered, free-spinning/pivoting front wheel. All the powered parts (wheels and brushes) have force-sensors so the robot can tell when it's stuck or caught on something. The unpowered front wheel has no motor, so force-sensors won't work. Instead it's two-toned so a photoeye can tell if it's still freely turning or not.




Here (below), I've removed the front wheel so you can see into its socket:



And here (below) is the same photo, but annotated. Click to enlarge:


This, below, is a poor photo (sorry!); a closeup of the front bumper. To the right, you can just see a glinting reflection of one of the forward-looking IR eye assemblies behind the translucent plastic. The plastic is a deeply tinted red, and I had no good way to photograph through it.



Here's the Roomba's back end, where the small vacuum fan exhausts:

The round button above the exhaust port is a latch. The whole fan/dust-bin/filter assembly pulls out.

Here it is, removed and swung open (below). Chunky debris gets caught in the top compartment. The vacuum fan draws fine debris and dust into the lower compartment, and the filter keeps the dust from entering the fan and being blown back into the room:


Here's a peek into the brush assembly. This is where the dust bin/fan/filter assembly plugs into:



The dust bin houses the electrical vacuum fan, so it's not immersable, but the filters are washable.


iRobot recommends cleaning the brushes every third use or so. They're very easy to get at. You lay the beast on its back:



Lift the brush guard...


... and the brush and beater bar just lift out in tool-less Lego fashion. The guides and bearings for these parts are also very Lego-like, and (although iRobot doesn't say this) they're washable too.


With the brush and beater-bar removed, you can see the dime-sized shielded microphone that "listens" for grit and tells Roomba to start its spiralling spot-cleaning mode.


It only takes a minute to clean Roomba's guts. I let the parts air-dry, and snap it back together later.

Tomorrow is Thursday, and I'll break from our Roomba coverage to tell you about a new Windows Secrets column. (I have to pay my bills somehow!) Then, on Friday, we'll wrap up this informal "Robotics Week" with some Roomba miscellany. If you have questions, this'd be a good time to ask.

The Roomba came with a 30-day money-back guarantee, and at first I didn't know if I'd keep the little critter. But having used it a while, I have to say I like it a lot.

It's not this, for sure:

but it gets the job done well. I'll keep my Roomba for the foreseeable future, or at least until something like this comes along. ;)