2.1. INTRODUCTION 7
Figure 2.1: The generic robust control model structure
Trace(M) trace of M(Pn
i=1Mii )
Block diagrams will be used to represent interconnections of systems. Consider the
example feedback interconnection shown in Fig. 2.1. Notice that Phas been partitioned
into four parts. This diagram represents the equations,
z=P11v+P12u
y=P21v+P22u
v=∆z.
This type of diagram (and theasso ciatedequations) will be used whenever the objects
P,z,y, etc., are well defined and compatible. For example Pcould be a matrix and z,
y, etc., would be vectors. If Prepresented a dynamic system then z,y, etc., would be
signals and
y=P21v+P22u,