Things are now moving along pretty well. Using the phidgets motor controller and a pair of encoder modules I can get good closed loop position control of the robot, and this morning ran the first few tests, with the robot actually rolling along the floor rather than being jacked up on a couple of books as it was whilst writing the motion control software and tuning the PID gains. I'm quite pleased with the results so far, and it does look like I'll be able to achieve a reasonable dead reckoning performance which can then be integrated with the vision system to give reliable navigation.

Currently the robot looks like this:

http://farm4.static.flickr.com/3208/2373724362_3b23854c8d_b.jpg

http://www.youtube.com/watch?v=8FRJxWcAzI4

http://farm4.static.flickr.com/3024/2372889549_b50154a8a3_b.jpg

http://www.youtube.com/watch?v=CByUznJRs_g

There's still much more to be done with the software, but I think most of the hardware hacking is now out of the way. I only have some cable tidying to do, and will perhaps make the head covering a little more robust to protect the cameras. At present the robot is still tethered to a mains supply, and I'll probably leave it that way until testing navigation over significant distances becomes an issue.