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Entries in Electronics (5)


The Dozer's Almost Here!

I'm close.  So close.  Last night I managed to get functional code working.  He could roll around the arena, turn around if he hit the line around the edge, and charge if he saw a target.  Phase 1 complete.

The bot was still pretty dumb at that point though.  There was a noticeable lag in reaction time when he needed to turn from the edge, and that sometimes led to partial out of bounds.  Not good.  Also, it only sensed objects directly ahead.

So today, I refined the existing code.  I have the old stuff to fall back on, so I almost started with a total re-design.  The sonar sensor was mounted lower on the servo, since I expect my opponents to be a bit shorter then me.  I also have it sweeping around successfully, and steering the bot in the general direction of a detection, solving (kind of) the "tunnel vision" issue.

When I tested the newest code out tonight, I realized another issue.  If an object (target!) was within an inch or two of the sonar, such as when in a charge, it could loose track of them, and the bot would turn away to look again.  So I did what I swore I wouldn't do until after the competition: I added MORE SENSORS!

The large plate I was planning to use as a pusher/armor in the front still hadn't been mounted.  I have decided I'm going to add a pair of small pushbuttons behind the plate, and if either is pressed, the bot will forgo all other activities, and push as fast as it can straight ahead until it sees the line or the button is released.  I tested this with a crappy bench rig, and wrote some code.  I think it'll work pretty well.  The plate also provides the advantage of keeping the optical sensors in a consistent light.  That should help keep the readings steadier in varying conditions this weekend.

He looks angry.  Probably because I'm rushing so much of this build.  Although I have to say, I'm pretty proud of myself so far.  I'm not normally this productive in this short a time.  I guess it's good to have a goal.


Sumo Sensor Suite

Got the Ping))) finished and working tonight.  It turns out that back in the day when I received this Dorkboard, I had powered it up with a straight 9V battery like an idiot, because I was used to these kinds of boards having some kind of regulation built on them.  Since the Dorkboard takes the minimalist approach to microcontroller design, it does not, in fact, include this feature.  I noticed what I had done when I touched the top of the chip, and nearly lost my fingerprints.  Whoops.

Well, back to my point here.  It turns out that I have at least one bad digital pin on this chip now.  I know this because I fought for almost an hour like an idiot trying to figure out why the Ping wouldn't ping.  I hope that's the only issue I have...

I also got the optical sensors wired and mounted tonight.  They seem to work alright as long as I incorporate some input smoothing across the readings.  If I don't, they seem to pick up every little piece of dust and crap on the bench.  I'll try them out with some black and white paint lines later this week.

So now, it's pretty much up to coding.  Which sucks, because that happens to be my weakest area right now.  Nothing like crunch time for inspiration!


Dozer Progress

Dozer has become more like a bot then most of my previous projects.  I actually managed to fix several issues I've always had with some of my tools and materials, and that's really helped.  So the chain of design now is mainly: SketchUp + table saw + scroll saw + 800 trips to Lowe's for screws = bot.

I decided since the competition limited the bot size to a rough 6" x 6" square, I'd want to maximize my entry to take advantage of as much pushing surface as I could manage.  I ended up with a 6" circle, with the tires silightly inset to help fit.  I ended up around 6 1/4" across.  Not to shabby for roughing much of it with hot glue and some bolts.

I'm still working on the sensor code, but I do have much of the physical issues under control.  Here's a few progress pics and a short video of the lil' guy running around my carpets on a random pattern.  Mostly 'cause he's blind at that point.




Update: Turns out that Facebook strips YouTube videos out of blogs it imports for some reason.  If you're looking at this from there, and want to see the vid, head on over to and get the REAL stories!


AVR Programming for the Fireflys

I really need to build a better harness to program these things before I solder them up.  Once I've got the LEDs soldered on, forget it.




Firefly Jars - SMD Soldering Fun

A few years back, I made a firefly jar for Kate in an ultimately successful attempt to show her how unbelieveably awesome a guy I was.  It helped that I was unemployed at the time, since these suckers are incredibly time consuming.  Now that relationship success is mine, I've been tasked with making six more for the impending wedding.  Yay!

After a quick Digikeying, I've been working on all the great assembly stuff.  The hardest part is working with the LEDs.  These suckers are SMALL.

I've found the best way so far of manipulating these little guys is by microclip.  Using magnet wire keeps the LED and wires as invisible as I can get in the jar, and the clips are easier to use then my fingers when soldering them on.

Yeah, I know.  Use the tiniest tip you can on your iron, and keep the temp below 530ish F.

It's a pain, but ultimately worth it.  Especially when you get to show them to family, and they see the awesome effect made by the code off of the Instructables link.  Quite nice!

It also helps to have a clean, well organized bench to work on.  At least I've made a bit of progress there recently.  Finally decided to mount as much as I can to the walls, and it's a HUGE help.

So until next time, I'll be plugging away a few LEDs now and then.  At least I've got like two months to finish!