Let's Make Robots!

1069-E1 - Hunting for Dust Bunnies

Hunt Dust Bunnies

Start where?

Almost a full year on LMR and still no "start here" robot. That would be getting really silly. Especially with all this Mr Basic stuff going on.

This project has been limping along for more than a month now. If it were not for the challenge deadline, I would have limped for another month.


Actually, the bot did mighty fine, a few weeks ago. Too bad I did not deem it video-worthy yet. Because it has only deteriorated since 8-(. I burned a mini servo by inserting five freshly charged NiMh AA's for V2. I filled one slot with a 0 Volt battery and the (fresh) servo acts fine again. But now the robot is lacking power.


Yes it is possible to drive your Mr Basic motors with a L293D chip.


I know, the motors draw way too much current for the chip to handle, but I coded around that. The motors in this program do not fire for more than 230 ms at once. The swirl manoeuvre being the only exception at 460 ms. Yes that number was pulled from my hat. The chip stays relatively cool this way.

Obstacle avoidance

This explains the jerky motion of the vehicle. It moves, looks around, decides where (left or right) it saw the least obstacles/most clear space. And then it turns in that direction. Sweeps the area again. If anything is blocking its path straight ahead, it will again decide which way to go. This code often results in the bot oscillating left and right. Not getting anywhere.

Cliff detection

The Sharp sensor is angled down by a bit. That way a reading of 0 (zero) indicates that there is no floor to drive on. That is treated in the code as just another obstacle.


Again, the first version of my bot handled those cliffs beautifully. Now, not so much.

Chair legs jungle

At first, I had my code just look forward. Only when an obstacle was detected right in front, would it start to look around and consider alternatives. The bot would constantly get stuck with one of the front wheels against a chair leg. Those are tricky! The new code that always looks around does not suffer from this problem.


Dust bunnies

And that's how it became the Dust Bunny Hunter. It crawled under my table, couch, cupboard. As it turns out, almost all my furniture has a minimal 12 cm clearance for my robot. The main picture shows how it reappeared from the jungle that is my living room.

Parked for now

This project is parked for now. 


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I know this is an old robot, but when I saw Elmer drive right over the edge of the stairs I just lost it and LOLed, drawing suspicious looks from my collegues.

It's not the fall itself but the way it stops, looks around, supposedly notices the gaping chasm and decides to drive into it anyway!

The sounds of the tumbling robot makes it even better.

Ok, I decided to follow mintvelts suggestion and give 5 stars for my Nr. 1, 4 stars for Nr.2 and so one, to give a clearer result for this contest. 

Sorry rik. Only 5th place in my rating. This doesn't mean, that this is a poor design. Its great as all others, but there is only 1 star left for this.

Hi rik, neat (when off duty) robot!

I'll give it 5 stars in real life ratings, but for the comp i'll have to rate it 3, sorry but i'm trying to grade my ratings by comparing the entrys :(

Top work though. 

I'm going to be kinder with the stars because you (a) have video compared to the jeep at the time i voted and (b) using short burst of power to get Mr. Basic running on an L293D. I was too lazy to think of this and just used a L298N (which still gets very hot even with a heatsink).

Your replacement "music"? reminds me of those animated plasticine men I occasionally see on TV. Perhaps he needs a trailer on the back with a dustbuster :D

Great video. As always. But I gotta be fair with the stars and all that. Mr First Robot just isn't as advanced or creative as the others. I have to judge the robot not the amusement factor of the video.


also: Frits made me be evil! 

I myself voted zero stars on this one.
Shame we cant vote "minus" .... then ...then the LMR vote software would for sure do a Boolean "Flip" and show a high score of 65536

is apparantly still driving this place.

Has to be the buggy firmware though...


I can tell he has been through quite an eventfull productive month,  - I take my hat off.

Extra points for the Polymorph sidecar battery holders and the front mount for the Sharp (it would be easy to include a screw for adjusting sensor for Cliff detection (whoever "Cliff" is)- i must add i held my breath at the stairs and his "fuzzy Logic" was true to form - classsic - made my day)

Super Video - informative - suspense - comedy - action. all the trappings of a Hollywood Classic......


I too had problemos with the overheating L293D until i found that if you have 2 of them they can be "PiggyBacked" ie sit one on top of the other and solder the legs together pin1-pin1 ....pin2-pin2 etc - when done it allows the the current too be shared - so doubling the current rating - nice trick Hey. (it also allows control using just 3.6V nicads). Apparently it still works when 5 are piggybacked together.

5 stars for the just in time production and the funny noise when the bot falls down the stairs.