Rockwell Automation 1771-QDC, D17716.5.93(Passport) PLASTIC MOLDING MODULE - Manual (Page 234)

Tune Your Machine
Chapter 10
10-6
General Guidelines for Velocity Tuning
If your machine will never run velocity profiles, skip this section.
In this section we present two procedures:
Tune Pressure Loops without an Oscilloscope
Tune Pressure Loops with an Oscilloscope
Repeat either one of these procedures as needed for tuning closed-loop
control of these velocity vs. position profiles:
Injection
Clamp Open (3 movements)
Clamp Open Slow
Clamp Close (3 movements)
Ejector (2 movements)
Follow these general guidelines when tuning closed-loop velocity profiles:
Disable ramping
Disable Expert Response Compensation (ERC)
Reset ERC values to zero by setting DYC05-B15 (B35/463) = 1.
(Pro-Set 600 resets this bit to zero after resetting ERC values.)
Important: Gain constants differ between velocity profiles. The dynamics
of loads being moved and different hydraulic characteristics warrant
separate VelFF tuning considerations for each profile.
Important: Never use feedforward gain and ERC in the same velocity
profile.
Important: In most cases, adding a feedforward term to the VelFF
algorithm makes it too sensitive and does not enhance loop stability.
Use proportional control with a zero feedforward term.
(Add feedforward only if required)
Use the highest possible P gain constant for injection profiles
for precise performance without hammering your hydraulics, but
use the lowest possible P gain constant for clamp and ejector profiles
for repeatable performance.
Use an oscilloscope, if available. You can tune loops faster and easier
with it connected to QDC module’s output driving the selected valve.
Important: If you have an oscilloscope, skip to Tune Velocity Loops with
an Oscilloscope.