Image Processing Reference
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4
3
Open-loop response
2
1
0
Closed-loop response
-1
-2
0
5
10
15
20
25
30
35
40
45
50
k
FIGURE 5.4
Open-loop and closed-loop response.
5.2.2 P OLE -P LACEMENT D ESIGN OF SISO S YSTEMS
Consider the SISO dynamic system described by the following state equation:
x ( k þ
1
) ¼ Ax ( k ) þ Bu ( k )
(
5
:
18
)
With the assumption that the system is completely state controllable using the state
feedback u ( k ) ¼ Kx ( k )
, we wish to place the poles of the closed-loop system
at
l N . This means that the eigenvalues of the closed-loop matrix
A c ¼ A BK are at the desired locations given by
l 1 ,
l 2 ,
...
,
l 1 ,
l 2 ,
...
,
l N . Therefore the
characteristic polynomial of A c
is
P (l) ¼jl I A c j¼(l l 1 )(l l 2 ) (l l N )
¼ l
N
N 1
N 2
þ a 1 l
þ a 2 l
þþa N
(
5
:
19
)
By Cayley
Hamilton theorem (Section 3.11.3), we have
-
A N
c þ a 1 A N 1
c þ a 2 A N 2
c þþa N I ¼ P ( A c ) ¼
0
(
5
:
20
)
But
P ( A c ) ¼ a N I þ a N 1 A c þ a N 2 A 2
c þþ A N
c
¼ a N I þ a N 1 ( A BK ) þ a N 2 ( A BK )
2
N
þþ( A BK )
(
5
:
21
)
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