[gnormhurst]

Originally Posted by jgannon

Blind dead reckoning works with any kind of robot, because its path is determined experimentally. Unfortunately, while that would have worked great last year, and it will work fine this year for knocking down the hanging tetras, it won't do you any good for finding the vision tetra. You do get a lot of inaccuracy with encoders and skid steer, because your powered wheels do a lot of slipping, and it's hard to estimate how much they are actually going to slip.

This is a great example of why the software and hardware design teams need to talk to each other. As the software guy, I told the hardware design guys that I strongly preferred using wheel encoders, which meant I wanted a drive system that did not have wheel slippage inherent in the design. Four-wheel drive systems must slip when turning, unless special measures are taken (like car-steering or those crazy roller wheels that slide sideways).

Two wheel systems are very easy to drive and control, and they don't slip while turning, so wheel encoders have a chance of being useful.