Just laying out some thoughts

Ok to keep Leo moving in the direction he's supposed to be I'm going to use:

A1302 Hall Effect Sensors on his front idlers coupled with magnets to give feedback on his track speed.

2125 Mesmic Accelerometer is used to detect and calculate drift on carpet, smooth floors, track skidding and bumps in the floor.

Even with those, there is still going to be a lot of error from track skidding, carpet nap, bumps in the floor, track wear, and from not being put back down exactly where he got picked up.

Going to use a PING(or other sonar type sensor) and a sharp or two map out his local environment to cross reference with his internal map. Basically, trying to program Leo in a fashion that biologicals think or at least my poor understanding of how I perceive my self and others do things.

Voltage monitors will be implemented as well so that Leo just doesn't 'die' in the middle of the room. He will know when to return to his base(home) to re-charge(to eat). So will have to figure out how to get a charging circuit into his little body as well as everything else.