P.I .V. control requires the knowledge of the motor velocity, labeled velocity estimator in Fig.3. This is
usually formed by a simple filter, however significant delays can result and must be accounted for if truly
accurate responses are needed. Alternatively, the velocity can be obtained by use of a velocity observer.
This observer requires the use of other state variables in exchange for providing zero lag filtering properties. In either case, a clean velocity signal must be provided for P.I .V. control. As an example of this tuning approach, we investigate the response of a Compumotor Gemini series servo drive and built in controller using the same motor from the previous example. Again, we begin with observing the response to a step input command with no external disturbance torque (Td = 0).