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 wooden deck, and the visible shudders and drift were not unexpected. Because of the deck surface sometimes the wheels seem to catch and this causes a fair bit of drift. It also has more difficulty gaining rotational velocity on this surface.