Rockwell Automation RSLogix 5000 Fuzzy Designer User Manual
Page 54
Publication LOGIX-UM004A-EN-P - March 2007
54 FuzzyDesigner Component Library
where .
Finally the control variable CV is computed in the following way:
in the case of dependent gains and independent gains respectively.
The controller can be used in two different modes – Manual mode
and Automatic mode (default mode). During Manual mode the
parameter Mode, which is defined by the input link, has to be set to 1.
In this mode the controller calculates the user defined control
variable, which is connected to the input link Man. During this mode
the controller calculates the internal state of the integrator from the
user defined control variable to achieve a bumpless transfer when the
operator changes the control mode from manual to automatic. In the
Automatic mode, when the parameter Mode is set to 0, the controller
provides the computed value of the control variable. If input links
Man and Mode are not fed, the default (automatic) mode is applied.
The component also provides the user additional features – output
limiting with anti-reset windup, dead band control and gain forgetting
factor.
Output limiting allows applies limits CV_min and CV_max to the
control variable. If the output limiting is enabled, and the computed
control variable exceeds the limits, the CV is saturated. When the
value of the computed control variable reaches or exceeds limits, the
integration is paused until the value of the computed control variable
comes back into the range.
The adjustable dead band DB lets the user select an error interval DBI
= [SP-DB, SP+DB] around the setpoint where the controller output
does not change as long as the error remains within this range. This
dead band lets you control how closely the process variable matches
the setpoint without changing the value of CV. There are two choices
of dead band type – zero crossing and no zero crossing dead band.
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