National Instruments Xmath Interactive Control Design Module ICDM - Manual (Page 117)

Chapter 13 Multi-Loop Synthesis
Xmath Interactive Control Design Module 13-6 ni.com
Figure 13-5. Root Locus Window During the Multi-Loop Design
Figure 13-4 shows an example multiloop configuration for the 3-sensor,
2-actuator plant. There are two loops: one from sensor 1 to actuator 1,
and one from sensor 3 to actuator 2. In multiloop design you can alternate
between designing each of the (SISO) controller transfer functions, with
the other fixed.
Figure 13-5 shows an example multiloop configuration for the 3-sensor,
2-actuator plant considered, redrawn showing C
(1) connected to P
equiv
,
which is the plant with all other loops closed (in this case, just one other
loop). While designing C
(1) , it is useful to think of it as the SISO controller
for the SISO “equivalent” plant P
equiv
. Again, notice that P
equiv
depends on
which loop you are designing.