TROUBLESHOOTING
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CYGNUS
MI 850A316 1 B
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9.5
Gain scheduling diagnostics
9.5.1
System is unstable
Problem:
The system becomes unstable as soon as Gain Scheduling is activated and stays unstable even if Gain
Scheduling is then deactivated.
Explanation:
When Gain Scheduling is activated the PID values are all overwritten by values determined from the Gain
Scheduling parameters. Disabling Gain Scheduling fixes PID at these new parameters which may or may not be
stable. Continue below for a complete description of Gain Scheduling.
9.5.2
Gain Scheduling problems
"Gain Scheduling Was Not Successful"
See Gain Scheduling Theory, section 9.6. For Gain Scheduling to work properly the following are all needed:
1) A properly calibrated diameter signal (voltage, velocity/RPM, or Fieldbus are all valid)
2) A set of PID values that gives a stable system at core and the diameter that corresponds to that system.
3) A set of PID values that gives a stable system at full roll and the diameter that corresponds to that system.
4) A finite value of Overall Gain. The factory default of 1.0 should normally be used. If the system is stable at
core and at full roll but is unstable at an intermediate roll, the Overall Gain can be reduced to give a stable
system. This is done automatically when using Quick Stabilize while Gain Scheduling is active. Quick Stabilize
is available at:
Home>>More..>>Program>>Quick Stabilize
Summary of Contents for Cygnus MAGPOWR
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