Rockwell Automation 1771-QDC, D17716.5.87(Passport) CLAMP AND EJECT MODE - Manual (Page 184)

Tune Your Machine
Chapter 10
10-11
If you cannot alter your velocity proportional term(s) such that observed
oscilloscope traces quickly level off without any bouncing or chattering,
verify your Unselected Valve Set-output Values are correct for your
application (Refer to chapter 7 and the discussion later in this chapter).
If you are satisfied with your Unselected Valve Set-output Values and still
cannot get the observed oscilloscope traces to quickly level off without any
bouncing or chattering, your control may require a small feedforward gain.
Without modifying the proportional term(s) determined by the above
procedure, slowly begin increasing the appropriate velocity feedforward
term(s) while running machine cycles until the observed oscilloscope
traces quickly level off without any bouncing or chattering.
Important: Do not enable ERC if you must use velocity feedforward
gain(s) to adequately tune your velocity profile(s).
In this section, we discuss the use and effect of many of the QDC module
setpoint parameters. This section is presented in a “discussion” format
rather than a procedural format similar to previous chapters and sections.
The discussions that follow assume familiarity with conventions,
terminologies, and procedures used in the Injection Molding Industry and
previously in this User’s Manual.
ERC Control
In previous chapters, all profile execution has been accomplished with the
QDC module’s ERC algorithms disabled (off). The QDC module utilizes a
proprietary, enhanced control scheme called Expert Response
Compensation. Expert Response Compensation (ERC) accounts for
changes in your machine dynamics, machine hydraulics, raw materials, and
other process variables. Using an exclusive algorithm, ERC adjusts the
open-loop and closed-loop control algorithms to counter-balance changes
to your process, both abrupt upsets and long term deviations.
Expert Response Compensation should be utilized whenever strict
adherence to pressure or velocity profile setpoints is absolutely required
during clamp and ejector operation. It is not necessarily required when
your primary objective is repeatable, high speed clamp and ejector
movement. It typically is not required to achieve repeatable mold full open
and ejector full advance positioning when running at any obtainable
velocity.
Important: Expert Response Compensation should not be enabled until a
control loop is already properly tuned and under control.
Other Tuning
Considerations