A PD controller has a proportional term and a derivative term, and independent parameters for each (per axis). This has one error term, and one parameter. If y

A PD controller has a proportional term and a derivative term, and independent parameters for each (per axis). This has one error term, and one parameter. If you think of the position as the variable being controlled, then it's just a "D" controller. If you think of the velocity as the variable being controlled, then it's just a "P" controller. But unless I'm experiencing some massive confusion, you can't think of it as a PD controller. Edit: I think I can see why you might think this is a PD controller. You can see that there's no overshoot or ringing, so you think to yourself that there must be a damping term. But the difference is that there is no plant process here! We can just decrease the error. That's why you will never get overshoot or ringing. In summary, it's a one pole filter on an error function, not a controller.