66 needs your help!

[Al Skierkiewicz]

As other have stated, your robot is reacting to the friction developed between the four wheels and the carpet in turns. You have to either turn two of the wheels when turning or reduce the side friction while turning. There are several ways to do this, one is to lift two wheels off the floor while turning. Another is to use a special type of wheel where there are rollers on the edge. It grabs in the forward motion but the rollers turn when the wheel is moving sideways. We developed such a wheel and the picutre is in the archive. Our mech engineer, Raul, calls them BUPOD wheels and they worked really great.

[Alexander McGee]

If it is 4x4, a quick, very good answer is pop-down casters on one side of the robot (front or back). You can either use one or two, and easilly position them with pnumatic cylinders.

[Dick Linn]

Originally Posted by magnasmific

If it is 4x4, a quick, very good answer is pop-down casters on one side of the robot (front or back). You can either use one or two, and easilly position them with pnumatic cylinders.

Yes, that or just a single big "hockey puck" made out of HDPE in the middle, beveled on the bottom so as not to snag. Or a bar of HDPE hinged on one end, whatever is simple and quick. Casters can handle funny, so we're gravitating away from them.

4-wheelers should have a short wheelbase and wide track in order to balance the leverage forces. Last year ot bot had about a 17 inch wheelbase and was fairly narrow, so we ended up using 2 pneumatic Skyway wheels and two of the solid polyurethane wheels (that were in the kit) to make turning a bit easier. It's still a bear to turn on pavement, but not too bad on carpet.