National Instruments NI-Motion - Manual (Page 38)

Chapter 3 Tuning Servo Systems
NI-Motion User Manual 3-10 ni.com
Figure 3-6. Alternate Dual-Loop Feedback Algorithm
NI Motion Controllers with Velocity Amplifiers
Velocity amplifiers close the velocity loop using a tachometer on the
amplifier itself, as shown in Figure 3-7. In this case, the controller must
ensure that the voltage output is proportional to the velocity. Use the
velocity feedforward term (Vff) to ensure that there is minimum following
error during the constant velocity profiles.
Figure 3-7. NI Motion Controllers with Velocity Amplifiers
in Addition to Kd