This video shows the KD01 (differential drive) robot executing a rotate-in-place movement using its PID controllers to accelerate to a set velocity counter-clockwise, decelerate to zero, and then do the same in a clockwise spin.
As electric motors don't generally run the same speed in both directions the PID controllers should compensate for this, and to a reasonable extent this test shows that they do, as the robot remains largely in the same location at the end of the test. Not perfect, but close. There's also a noticeable jump as the robot begins to rotate clockwise. I'm not sure why this occurs but as this test is to determine if the robot can spin in place successfully I'll ignore that for now.
Notice that the robot pirouettes very slowly to the right, ending about 4cm from its starting point. This error is evidence that even with the PID controllers the mechanics of the KD01 design are not perfect, i.e., that the alignment of the motors, location of the caster, weight balance, wheel slippage, or some other factors are at play. But all in all, this test can be considered a success.