National Instruments Xmath Interactive Control Design Module ICDM - Manual (Page 87)

© National Instruments Corporation 11-1 Xmath Interactive Control Design Module
11
Introduction to MIMO Design
The following chapters describe the use of ICDM for MIMO design. NI
assumes the reader is familiar with the use of ICDM for SISO design. In
many cases, the texts describe the differences between SISO and MIMO
design.
This chapter provides an introduction to MIMO design. ICDM
automatically switches between SISO and MIMO modes depending on the
plant that is read in. To try out the MIMO features described here and in the
next two chapters, you must first either read in a MIMO plant, or select the
MIMO plant from the Default Plants submenu in the Read Plant menu.
Basic Terminology for MIMO Systems
The following sections define the basic terminology and notation used to
refer to MIMO systems in ICDM, for analysis and plotting. The LQG/H
∞
Synthesis window uses additional terminology described in Chapter 12,
LQG/H-Infinity Synthesis .
Feedback System Configuration
ICDM uses the feedback configuration shown in Figure 11-1. The
configuration and signal names agree with the standard SISO configuration
shown in Figure 2-1, with two differences. Here, all signal paths represent
vector signals, whereas in the SISO setup, the signals are scalar. There is
also a new signal, d
act
, that subtracts from the actuator signal. This signal
can be thought of as an actuator-referred disturbance signal, an actuator
noise, or just a fictitious input that allows you to see the transfer functions
from the actuator to various other signals.
The equations describing this system are:
where, as shown in Figure 11-1:
y denotes the plant output or sensor signal, which is a vector of size n
y
y P u d
act
–
( )
= u Ce = e r y – =