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My "nineteenth" attempt to make a four-wheel robot using Lego Mindstorms nxt. All ended in failure as I couldn't get any of them to turn. This was a kind of articulated tractor-trailer effort, but still no good. I've rturned to two wheel / skid-steering for now.
This is a companion discussion topic for the original entry at https://community.robotshop.com/index.php/robots/show/sh-tbot