
Chapter 8 H-Infinity Synthesis
© National Instruments Corporation 8-3 Xmath Interactive Control Design Module
Opening the Synthesis WindowThe H∞ window can only accept H∞ controllers. If the current controller is 
of type H∞ (perhaps from the History window) and the H∞ window is 
opened, the current controller is read into the H∞ window; that is, the 
parameters are set to the appropriate values.
If the current controller is not of type H∞, and the user attempts to open 
the H∞ Synthesis window, a dialog box appears and warns the user that 
proceeding with opening the synthesis window will overwrite the current 
controller with the controller.
The H∞ window remembers its parameter settings. When it is opened, the 
parameters will be exactly as they were when the window was last closed, 
or they will be set to default values if the H∞ window has not been opened 
in this ICDM session.
Setup and Synthesis MethodThis section describes the closed-loop transfer matrix (refer to Figure8-2). 
The H∞ synthesis procedure can be described using the following standard 
setup:
where y is the plant output signal
w1 is a normalized (input-referred process) noise
w2 is a normalized (sensor) noise
z1 is the normalized actuator signal
z2 is the weighted plant output signal
P is the plant transfer function
C is the controller transfer function
W is the output weight transfer function
yPuw
1
+()=uC–()yνw2
+()=
z1ρu=z2Wy
=