Stepper-driven tank platform for remotely operated vehicle

First: Some history.

I found this cheap wifi pan-tilt camera on ebay. It's a Foscam knockoff, and I bought it for about AUD$60 delivered. I strapped it to the top of a cheap RC car chassis, compiled an application for the camera, wrote it into the ROM, banged out some python, stuck on an arduino and had a bit of fun:

http://www.youtube.com/watch?v=UcSHahwmB0A
http://www.youtube.com/watch?v=1wuCoz7Y2VY
http://www.youtube.com/watch?v=Qv-Fi1xO2k0
http://www.youtube.com/watch?v=6vcNZrvgPe0
http://www.youtube.com/watch?v=ovcEQWTNXWE
http://www.youtube.com/watch?v=nKPFiUtFl9E

The car was fun, but unusable over high-latency links due to its high speed and fairly unpredictable trajectory. It also had a terrible turning circle.

I've just finished designing a printable tank chassis for the camera. I re-jigged the control system to be wholly contained within the browser, using poorly-documented cleverness to send data straight to the camera's serial port. The result is a remote-controlled tank that can point a camera around independently of the body, that works anywhere there's wifi reception and behaves well enough to control over a 500ms internet connection:

http://www.youtube.com/watch?v=Z53KcBvMl48
http://www.youtube.com/watch?v=U-rNHdH7mmU

I have successfully driven it through medium-length grass, over, under and around my house. It's a bit top-heavy at present, I need to move the battery lower to lower the centre of gravity. I predict about half an hour of usage from a 2200mAh 3 cell lipo battery, but I can't say for sure since I've never flattened one.