National Instruments Xmath Interactive Control Design Module ICDM - Manual (Page 20)

Chapter 2 Introduction to SISO Design
© National Instruments Corporation 2-5 Xmath Interactive Control Design Module
LQG Synthesis Window
The LQG Synthesis window synthesizes LQG controllers, and therefore
can be used only with strictly proper plants. The user can vary weights for
the ratio of control (input) to regulation (output) cost and the ratio of sensor
(output) noise power to process (input) noise power. Optionally, the user
can specify a guaranteed decay rate and integral time constant. By dragging
zeros on a symmetric root locus plot, the user can vary the state weighting
or perform LTR design.
There also is a MIMO LQG window, described in Chapter 12,
LQG/H-Infinity Synthesis .
H-Infinity Synthesis Window
The H
∞ Synthesis window synthesizes central H∞ controllers (also called
minimum entropy, risk sensitive, or LEQG controllers). The user can vary
weights for the ratio of control (input) to regulation (output) cost, the ratio
of sensor (output) noise power to process (input) noise power, and the risk
sensitivity or H
∞ bound parameter γ. The user can vary the state weighting,
or equivalently, the output weight transfer function, by dragging zeros.
History Window
The History window is used to display and manipulate the design history
list, which is a list of controllers that have been explicitly saved during the
design process. The History window can be used to rapidly cycle through
and compare a subset of the saved designs. Any controller on the history
list can be recalled, and the design process continued.
Alternate Plant Window
The Alternate Plant window is used to study the robustness of a controller
to variations or changes in the plant. The user can interactively vary the
plant gain or dynamics, or add extra parasitic dynamics to the plant, see the
effect on the closed-loop system, and compare it to the nominal system.
Key Transfer Functions and Data Flow in ICDM
ICDM has three key transfer functions:
• The plant transfer function P
• The alternate plant transfer function P
alt
• The current controller transfer function C