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.

Mesmic 2125

Was looking around Radio Shack last Friday and found a Mesmic 2125 accelerometer in the sensor bin, I also found a PING module from parallax too. Got the accelerometer, but not the PING module. I like to stay within a budget and I think I can find the sonic module cheaper online with S&H included. Got it home, got it hooked up, wrote a sketch to look at the data stream.   So may have to do some data sampling. Writing some procedures to do some data logging. I will find out tomorrow evening if they are worth the time it took to write them.

Working on bumpers and redoing the design

Well got the rocker switches for the bumpers. Just need to put a few pull down resistors, screw them in and attach the bumpers. I did find a Mesmic 2125 accelerometer at Radio Shack for $32.99 plus tax, but found a 3 axis one at adafruit.com for $20 plus S&H. The latter is out of stock though and has been for a couple of weeks now.

I did order the magnets for the tachometer part of Leo today as well. Using 1/4" rare earth magnets on the front wheels coupled with analog hall effect sensors. Will probably order them this week or find them on ebay.

Just need to mount the switches and redo the bumpers on Leo. I was thinking about putting the IR ranging sensors in the drive part of the body, but starting to run out of room in there with batteries, switches, the drive board and still need to put another or change out the battery packs altogether. A few different options, especially if I make Leo an autonomous being and therefore able to charge himself when he needs to. That is sometime down the road.

The drive unit will be using up 7 out of 11(I don't count the tx and rx pins) digital I/O pins and 5 analog pins. I have 3 clones that I bought from Dale and need to build them up, but need to get a lot more familiar with the arduino I already have.

Well off to do something, even if it's wrong!