Let's Make Robots!

Vaccum bug

This robot is navigates by (avoiding) wall and cliff. It moves around the floor, vacuuming it.

As my first microcontroller robot, I have made a two-wheeled robot with bumper switches and edge-detction (because I have death-causing cliffs in my house). The next step is to install a switch to turn on a sucking fan, although I'll have to add an additional power supply in this case, other wise the poor thing will only run for a short time before dying.

It uses a picaxe18X to poll the bumper switches and the IR detectors, then signal to a 74AC240 octal inverter chip which drives the motors. Both the picaxe and the motor driver are mounted on pcbs that I etched on my balcony - etching is fun, but can leave horrendous stains if you drop even a tiny bit of acid...

I'm not completly happy with the algorithm at present - Ideally, I'd like to have interrupts triggered by the bumpers, and by the IR sensors - it's easy enough to have an interrrupt attached to a  physical switch, but less easy to have an interrupt triggered by a condition that needs to be calculated... (unless somone has a bright idea?).






VacBot, profileThe red case is a "hand vaccum" that I got at a local store here. As you can see, there have been a few iterations of ideas and so there's a few holes cut into the case with no apparent purpose.

The first mistake was using LDRs and bright LEDS for obstacle avoidance, but this really didn't work very well for fine objects, such as chair legs, power cables etc, besides, I want this robot to get RIGHT INTO the corner. Reflection by light really won't work for small, dull things (such as wooden chair legs..)

Oh, the hole here is just the acess for the programming jack







Bumper switches are made from heat-molded acrylic. They were cut to that funky shape so they will be triggered by any obstructions on the ground, such as powercords (there's a few power cords lying around), dumped bags or whatever on the floor (sloppy people, I know, that's why I'm trying to make a vacuuming robot, so I can be even sloppier


Yep, the price tag says 105 yen. that's what that stupid little battery-holder-with-switch cost me - and a rough approximation of the bot's total worth.




IR detection & sensor



The Cliff detection caused me some grief, and here's the reason why; I think it's been noted often that the angle of the IR sensor is critical, I have to say - it really really really is. I had to tweak the angle of the detector so that it was pointing directly at the IR reflection. I did this by trial and error, watching the readadc values as I adjusted the angle.







The circuits for the IR detector/sensor system was pretty much identical to that given by oddbot (here). Here's a copy of the circuit, and PCB I used;

IR detection/sensor circuitPCB











motordriver schematic


motordriver pcbIn case it's interesting, the left is the schematic for using the 74AC240 octal inverter as a motor driver - I don't know too much about what is better or best, but this IC seems to be really great as a cheap motor driver - and it has a lot of other uses too.



In the pcb diagram on the right, I put in a couple of protectiondiodes across the motor terminals. It's a really compact board - much (much much) easier to etch than to freeform.


assorted debris!

Update!; the proof that the vacuum works too..All this after 10 minutes!


(yes, the house is dusty..)


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This is one cool concept - never thought of putting wheels on a mini-vaccum - i need one for my Praxis (true you can buy a roomba - but where is the fun in that).

 Do you like stressing your "VB" i had to  "double take" when you tried to steer it down that Stairwell (Majour Gulp) - though it shows great trust in your programming & mechanics.


Nice job......

Thanks Gareth, But if it DID launch into the abyss, I probably wouldn't have posted the video... 

or maybe I would! - perhaps we could have started a "classic robot deaths" page. I think rik might have a video that would fit ;)

HeHe - Anyone that would allow a bot to cruise so close to "The Edge" would for sure post the results....... it would have at least filtered the air during its plummit.

..... Yes riks Mr.falldownthestairs bot would rank high..... (cant find the vid though)

There is a newer vrsion of the 74AC240 octal buffer chip[ called the 74AC540.

the '540 has all the inputs on the left side and all the outputs on th rght side, and is much easuer to lay out.


It is good to see more of the nine-year old BEAM robot building techniques show up on LMR. But let's give creidt where credit is due. 

Everything old is new again. 

Looks like a new hybrid car :D Did you add the clear plastic wrap arounds or were they part of the original vacuum cleaner?

Are you making up your own PCBs now?

I added the plastic bumpers. I use my griller to warm the plastic enough to be deformable and it's pretty easy to do.

hmm, one day I might write a tip/wt about heat-shaping acrylic, if one doesn't exist already.

I make my own pcbs where it's handy - In this case the circuit for the IR sensors is small enough so I didn't have to, but I used Eagle to help me minimise the size of the circuits. The picaxe and the 74AC240 motor driver inside are both mounted on boards that I etched myself.


Plexi forming would be a nice tip to have.

Ed Roth used to make the big bubble tops for his cars by cutting a big circle out of a piece of wood, laying the plexi on top, and throwing the whole thing in a pizza oven until the dome sagged through the hole.

When I get a sec, I'll video it getting stuck in a corner.

I hope that every one can control their excitment for such a visual bonanza..