National Instruments Xmath Interactive Control Design Module ICDM - Manual (Page 81)

© National Instruments Corporation 10-1 Xmath Interactive Control Design Module
10
Alternate Plant Window
This chapter describes the form of the Alternate Plant window used for
SISO design; refer to Chapter 11, Introduction to MIMO Design , for the
form used for MIMO design.
Role and Use of Plant and Alternate Plant
In addition to the plant P, ICDM can optionally maintain an alternate plant
P
alt
. These two transfer functions have different uses and purposes:
• The plant is always used for the synthesis windows (that need it). For
example, when synthesizing an LQG controller, the LQG synthesis is
based on the plant P. In other words, the plant is used for design. In
contrast, the alternate plant P
alt
is never used by any synthesis method.
• The alternate plant P
alt
is used only for analysis. Specifically, by
turning on the Alternate Plant display (refer to the Displaying the
Alternate Plant Responses section) the plots in the ICDM Main
Window will show the alternate plant connected with the current
controller and the plant connected with the current controller.
• It is not possible to change the plant in ICDM except by reading it from
Xmath. In contrast, the alternate plant can be manipulated using the
Alternate Plant
window.
You can think of the plant P as the plant model used for control system
design, and the alternate plant P
alt
as the plant model used for control
system validation.
Displaying the Alternate Plant Responses
The ICDM Main window plots always show the response of the controller
connected with the plant. By turning on the Alternate Plant display, the
responses of the controller with the alternate plant also are shown in these
plots.
You always can use data-viewing to determine which plot corresponds to
the plant and which corresponds to the alternate plant.