Mike is about to post the dissection of the F-350 SuperDuty Ford Truck, that looks like it has servo steering control and a nice planetary gear system. Given that this is the case the robopet team is in need of an initial design and some more parts. ASAP. Kev has characterized the robopet behavior and is posting the dissection. Some links to get you going:
http://wiring.org.co/
http://www.seattlerobotics.org/guide/servos.html
http://wiring.org.co/reference/electronics/servo.html
and then the sensors that your dog will use will depend on the site of investigation.
Go!