Rockwell Automation 1771-QDC, D17716.5.85(Passport) MNL. PLASTIC MOLDING MODULE - Manual (Page 152)

Tune Your Machine for Producing Parts
Chapter 10
10-6
Tune Velocity Loops without an Oscilloscope
Before you begin tuning your velocity loop, confirm that you:
selected the velocity vs. position algorithm
selected closed-loop control
zeroed the velocity feedforward term
did not change the proportional term that you entered in chapter 7
disabled
ERC
reset ERC values
disabled
ramping
downloaded all setpoint changes to the QDC module
1. Enter the desired operational profile for a production cycle.
2. Run several profile cycles while comparing profile actuals returned in
status block IPS with profile setpoints in command block IPC. Also
observe hydraulic hoses leading to the injection cylinder as follows:
If: Then:
Observed actuals are consistently well below
profile setpoints
Increase the proportional term
Observed actuals are consistently well above
profile setpoints
Decrease the proportional term
Excessive hammering and vibration is
observed in the cylinder's hydraulic lines
Decrease the proportional term
Important: Each time you change a gain constant, you must download the
change to the QDC module. Refer to the download procedure in chapter 4.
3. Re-run the profile after each change to the proportional term until
observed actuals are close to setpoints without hammering and
vibration in hydraulic lines to the injection cylinder.
Important: If you cannot make velocity actuals match entered setpoints,
verify that your Unselected Valve Set-output Values are correct. Refer to
this topic later in this chapter or in chapter 7.
4. If you are satisfied with your Unselected Valve Set-output Values and
still cannot match velocity actuals to desired setpoints, your control
may require a small feedforward gain.
5. If necessary, slowly increase the feedforward term while running
machine cycles until velocity actuals satisfactorily match entered
setpoints.
Important: If you must use feedforward gain to adequately tune your
velocity profile, do NOT enable ERC for this profile.