Error AutoTune IL_TempControl

[David08]

Hello,

A customer is using the FB IL_TempControl, to control the temperature of a welding for plastic containers.
The problem is that we have followed the manual and we have made the graph to obtain the data of Ks, Ts and Tt. Attached graph:

When starting AutoTune with these values, after a few seconds it gives a "Calculation error" error and we have no further diagnosis.

Any idea what parameter or value might be wrong for AutoTune not to work?

Thanks in advance.

[Thoomas · Accepted solution]

Hard to say ...

Please have a look in the manual https://docs.automation.boschrexroth.com/doc/172933738/il-tempcontrol/1-07/en/ and there in the chapter "Information on specific errors" ...:

• "Identified controlled system parameters are invalid, self-identification of the controlled system failed"
  (Additional1 = 16#0A0F0104; Additional2 = 16#0C230075):
  The identification of the controlled system response and the resulting controller parameterization failed.
  • "ControlMode:= CONTROL_TEMPMODE_ONLY_DISTURBANCE":
    Cause: The "AutoTuneMaxPower" input is too large for the existing controlled system. Consequently, the distinctive controlled system reaction could not be detected within the first half of the actual value change.
    Troubleshooting: Reduction of the input "AutoTuneMaxPower".
  • "ControlMode:= CONTROL_TEMPMODE_OPT_xxxxx":
    Cause: Identification failure can cause a unfavorable specified controlled system delay time "ContrParam.Tt", a task interval that is too high, a controlled system that is not sufficiently transient at the identification point in time, a controlled system initiation that is too low or an incorrect actual value detection (sensor not connected).
    Troubleshooting: If the auto-tuning failed due to an incorrect sampling time, a rough estimation of the controlled system delay time can be specified as information on the auto-tuning at the "ContrParam.Tt" input and/or the task interval can be reduced. If the auto-tuning of the temperature controller failed due to the controlled system not being sufficiently transient, the repeat the auto-tuning with a stationary transient controlled system. If the auto-tuning failed due to an insufficient controlled system initiation, repeat the auto-tuning with a bigger command value change. If the temperature detection is defective, the error has to be recovered

[Shangkun]

I think there are some possibilities here in identification.

1.  the gradient of y(control system output) is persistent in some cycles.
2. u(control system input) never be changed.
3. delay time of calculation is negative.
4. gain of the control system is 0 or response time is negative or delay time is negative.

In particular,  the temperature control system is a nonlinear system with a large delay time and a large response time, and it is difficult to identify it. So it is hard to calculate if we use the linear transfer function to fit or if the data quantity is worse.