Many FRC robots make use of a tank drive - that is, all wheels on the left of the robot (the left wheelset) are mechanically linked to run at the same speed and driven by a single or cluser of two or more motors that are driven at the same power either by direct drive or via more often a gearbox. An identical arrangement is used to drive the wheels on the right of the robot (the right wheelset) .
The left and right wheelsets are controlled independently. If both wheelsets are driven at the same speed and direction then the robot travels in straight line forwards. If both
wheelsets are driven in the other direction then the robot travels in a straight line backwards. If the wheelsets are driven at different speeds and/or different directions then the robot will travle some form of curved path. Calcualting the radius of this curved path (or turining circle) for a tank drive robot is the topic of this article.