I'm finally slapping together a quickie bot using my Vex wheels. I always wondered about whether there's an optimum chassis aspect ratio (wheelbase vs width, x pattern, square, rectangular). I asked a few builders and the general consenus was no. I started to roughly copy Rich's very cool-looking Expo bot's proportions. But when I got just the front 2 wheels on the chassis, I rolled it around on the floor and it pivots perfectly around a point on the chassis, pretty far forward of about where Rich's rear axle centerline would be. That is, if I move my rear "axle" somewhat forward of what looks proper, then the robot will be able to pivot perfectly (no wheel scrubbing) around the middle of the rear axle just by driving the two rear wheels in opposite directions, with the front wheels not powered. And vice versa. It will make the chassis look wide and quite frankly, a bit goofy, but something tells me that's the way to go for optimum maneuverability with the weight evenly distributed between all 4 wheels. I know Rich & Duane have built their mecanum bots. Any feedback, guys?
Maybe the answer is online, I just haven't found it yet.
I'll post a pic tomorrow.