GPS-X Technical Reference

Tools Object 354
Feedforward Controller Parameters
The parameters of the pidforward model are presented in three menus: Manipulated
Variable, Controlled Variable, and Disturbance Variable. Feedback control
parameters are located in the Controlled Variable menu and feedforward control
parameters in the Disturbance Variable menu.
The feedforward controller parameters found in the Disturbance Variable form are
detailed as:
Feedforward controller (ON - OFF): The feedforward component of the
controller is activated by this switch.
Disturbance variable with label: The cryptic name of the disturbance variable
including the stream label.
Controller sampling time: The length of time between controller executions.
Feedforward gain: The feedforward controller tuning parameter, K FF.
Lead time: The feedforward controller tuning parameter, ld.
Lag time: The feedforward controller tuning parameter, lg. The ratio of lead to
lag times should usually be kept below 2:1 to minimize the effects of noise.
Dead time: The feedforward controller tuning parameter, .
Negative feedforward gain (ON - OFF): This parameter controls the `direction'
of the controller. The `normal' sign of the feedforward gain is negative. This
occurs when both the process and disturbance gains have the same sign, in which
case this setting should be ON (the default value). Otherwise, it should be OFF.
For information on tuning Feedforward/Feedback controllers, consult Marlin (1995).
GPS-X Technical Reference