Wednesday, March 28, 2007

NXT + webcam + PC = not quite there yet.

...but we're getting closer!

Last night I took a couple of hours and finished up my "Complete redesign from the ground up."

Looks quite a bit different from the first video. A few "minor" changes:
  • Integrated a 4 shot rotary magazine. (borrowed the idea from JP Brown though it took me forever to figure out how to mount the cyberslam missiles!)
  • Improved the base stability.
  • Reworked the turntable mechanism at LEAST 3 times. First time used a conventional 40 tooth gearwheel. (too much slop) Second and third used the NXT turntable. (Had the dickens of a time trying to figure out how to mount and drive it...finally ran across some examples and was able to get some traction)

Pretty cool, eh?

And then I hook it into the motion tracking system...

And it doesn't work.

Moves too quick. Not enough precision. Left/right can possibly be used as is, but direct driving the up/down movement is just tooooooo fast. Additionally, when only applying 10-15% power to the motor to rotate up/down (the idea being to do it sllloooowwwwllly) not enough juice gets to the motor to move it! (especially if the batteries aren't brand-spanking-new.)

Amazing, isn't it, how you can never anticipate the areas that'll really getcha? I hadn't a clue that the pan/tilt would be such a challenge.

Nor did I figure that simply setting the webcam's res up from 160x120 to 320x240 would drive a software refactoring/revision/redesign.'s a good thing. The new base is MUCH more stable. The new pan mechanism is rock solid compared to the last.

And the software redesign I used to start writing unit tests for the tracking modules I'd written. Which forced me to rethink some of the design. Which is a good thing.

So...back to the drawing board! And maybe with this rev I can get it a leeeetle more compact. That was another thing...this version is just monster-lovin huge. Wiiide. (though I must admit that it makes it look a bit more imposing. )