Image Processing Reference
In-Depth Information
4.6.2 S TATE E QUATIONS
The general expressions for state-space equations of a MIMO dynamic system are
given by
x ( k þ
1
) ¼ f ( x ( k )
, u ( k )
, k )
(
4
:
82
)
y ( k ) ¼ h ( x ( k )
, u ( k )
, k )
(
4
:
83
)
where
x ( k ) ¼ x 1 ( k )
T is the N
½
x 2 ( k )
x N ( k )
1 state vector
u ( k )
is the M
1 input vector
y ( n )
is the P
1 output vector
The functions f and h are nonlinear and are de
ned as
2
3
f 1 ( x 1 ( k )
, x 2 ( k )
,
...
, x N ( k )
, u 1 ( k )
, u 2 ( k )
,
...
, u M ( k )
, k )
4
5
f 2 ( x 1 ( k )
, x 2 ( k )
,
...
, x N ( k )
, u 1 ( k )
, u 2 ( k )
,
...
, u M ( k )
, k )
f ( x ( k )
, u ( k )
, k ) ¼
.
f N ( x 1 ( k )
, x 2 ( k )
,
...
, x N ( k )
, u 1 ( k )
, u 2 ( k )
,
...
, u M ( k )
, k )
(
:
)
4
84
2
4
3
5
h 1 ( x 1 ( k )
, x 2 ( k )
,
...
, x N ( k )
, u 1 ( k )
, u 2 ( k )
,
...
, u M ( k )
, k )
h 2 ( x 1 ( k )
, x 2 ( k )
,
...
, x N ( k )
, u 1 ( k )
, u 2 ( k )
,
...
, u M ( k )
, k )
h ( x ( n )
, u ( n )
, n ) ¼
.
h P ( x 1 ( k )
, x 2 ( k )
,
...
, x N ( k )
, u 1 ( k )
, u 2 ( k )
,
...
, u M ( k )
, k )
( 4 : 85 )
If the system is linear, then the state equations can be written as
x ( k þ
1
) ¼ A ( k ) x ( k ) þ B ( k ) u ( k )
(
4
:
86
)
y ( k ) ¼ C ( k ) x ( k ) þ D ( k ) u ( k )
(
4
:
87
)
If the system is LTI, then matrices A, B, C, and D are constant matrices and the state
equations become
x ( k þ
1
) ¼ Ax ( k ) þ Bu ( k )
(
4
:
88
)
y ( k ) ¼ Cx ( k ) þ Du ( k )
(
4
:
89
)
where A, B, C, and D are N N, N M, P N, and P M constant matrices,
respectively. The block diagram of an LTI control system in state-space form is
shown in Figure 4.6.
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