Madox.NET

Another failure!  Though all signs pointed to it working…

So I got a freebie OddBot sent to me a couple of weeks ago, it basically is a derivative of my Mecanum Rover and Olaf was kind enough to sent it with almost everything attached less the Chumby.  Since I’ve been on a TI Launchpad buying spree, I thought I’ll tack one on in place of the Chumby to drive it.

So far this post reads like a gigantic spam with all those links…no enlargement links coming up, I promise…just one short video of it not working and running away on me.

So I figured, how hard can it be?  I procrastinated soldering 2 header pins onto the Launchpad’s TP1 and TP3 tie points for power but after doing that everything was almost recycling :-

Code – Copied from Madox Kart prototype code and original Rover code…took around 15-30 minutes to copy/paste and tidy up some comments.
Carrier for Launchpad + Battery +  Breadboard – Almost a direct copy of the Madox Kart prototype again… 15minutes to tweak and 1+ hour to print.  [Ok 3+ hours, 1+ hour on 0.4mm layers but 3+ hours on 0.2mm layers which I'm a sucker for].

Everything seemed ‘too easy’ so far, even the code compiled first time which I didn’t believe.  Then the problems started mounting…

Problem 1 – Cheap mini-USB cables from eBay failed to connect to the Launchpad properly.  Cable 1 was a complete no go (marked for butchering into a power cable), cable 2 worked only if the connector was held at a particular angle.  I programmed the Launchpad while keeping my hand steady holding the cable.  Cheap eBay USB cables, you disappoint me yet again.

Problem 2 – Connected everything up onto the breadboard and all, no blinky lights on the Launchpad!!!  Head scratch for a total of ~30 seconds.  It turns out it is the age old problem of ‘slightly too fat’ AA cells.  The AA cells are just a bit too wide for the battery holder and because of such, the friction between batteries was stronger than the spring and the + terminal wasn’t making contact.  Don’t know whether to blame this on the battery holder or the batteries…

Problem 3 – Continuous rotation servos were not zero’ed, and they were a pain to do so, the slightest adjustment movement will have it spinning the other way.  2 minutes later the zero’ing seems to have been gone, probably due to temperature drift (heating up) – PITA.

Problem 4 – My favorite – it didn’t work.  Initially because I didn’t pair the Wii Nunchuk (Duh! moment) and then probably down to the hackity software code  The movement matrices seemed wrong and the servo control was very odd, need to debug that later.  Highlight – IT RAN AWAY ON ME.  Best illustrated in video form :-

Problem 4.5 – The wheels haven’t been treated with Plasti-Dip or any other grippy surface, so its still very slippery…

I’ll upload the code etc when I get around to fixing it…

This entry was posted on Wednesday, December 28th, 2011 at 01:38 and is filed under Perverse Applications of Science.... You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.