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DIGITAL INDUSTRIAL CONTROLLER
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If Tune has been activated in the configuration or parameterisation level, the Tune
function is executed once the next time the setpoint changes and is then deactivated
automatically. This also applies to commissioning. In doing so, the controller
parameters are determined directly and once only by definition of the critical closed-
loop gain and the period of a brief limit cycle oscillation of the actual value generated
under controlled conditions (Figure 40).
7.4 Operating principle of the tuning and adaption modules
Figure 40: Operating principle of the tuning module
When additionally using the adaption function, the transient response is
characterised each time the setpoint changes during the process sequence. The
fuzzy logic module adapts the controller parameters if the response of the controlled
variable deviates from a given ideal response.
The ideal response is based on a transition response with the shortest initial
stabilisation time at approx. 5 % overshoot (Figure 41). An aperiodic transition
response without overshoot (with a correspondingly longer initial stabilisation time)
can be optionally set (Figure 42).
If both Tune and Adaption are activated, then Tune has priority, i.e. at the next
setpoint change Tune is first of all executed and then deactivated. In the event of
further setpoint changes, then only adaption is realised.
SP
PV
100 %
30 %
Setpoint change
Actual value progression
Limit cycle oscillations
Tuning phase
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