This video shows the KR01, a skid-steer 4 wheel differential drive robot, executing a rotate-in-place movement using its PID controllers to accelerate to a set velocity counter-clockwise.
In comparison to the KD01 robot, which has two drive wheels and a caster, the KR01 is a "skid-steer" robot, its four wheels driven as two pairs, operating much like an army tank. The tires on the robot are relatively soft silicon rubber, so the more friction between the wheels and ground, the more difficult it is for it to rotate in place. This test is on a smooth but non-sticky particle board, and the visible shudders and drift were not unexpected.