2.1. z -.
. 2.1.1 . . , . , .
. 2.1.1
() , . , . - (). () - (). x (t) x (k D t), k = 0, 1, 2 .
, x (k D t), .
, , , D t . , . 2.1.2. x (t) x* (t) = = x (k D t) d(t k D t), k D t , d(t) - ().
. 2.1.2
, x (t), . 2.1.3, x* (t). x* (t) ( ), t = 0, D t x (k D t).
. 2.1.3
, x* (t) p (t). ( , ), . 2.1.4.
. 2.1.4
x (k D t) k D t < t < (k +1)D t, . 2.1.5 k = 0. , x (k D t) . . 2.1.5 . ,
. (2.1.1)
|
|
. 2.1.5
, , D t. . 2.1.6.
. 2.1.6
Z - .
x* (t) x (k D t)
. (2.1.2)
(2.6.2) (. 1.3.1 . 19),
. (2.1.3)
es D t. z = es D t, , z-
. (2.1.4)
2.6.1. z - X q (t)
. (2.1.5)
z - f (t)
. (2.1.6)
2.1.1 z - , 2.1.2 . 2.1.1 MCS.
2.1.1
x (t) | X (s) | X (z) |
, q (t) | 1/ s | z / (z 1) |
d (t) | ||
d (t k D t) | exp( k D t) | z -k |
t | 1/ s 2 | D t z / (z 1)2 |
exp( at) | 1/(s + a) | z / [ z exp(aD t)] |
1 exp( at) | 1/ s (s + a) | z [1 exp(aD t)] / (z- 1)[ z exp(aD t)] |
sin(w t) | w /(s 2 + w 2) | z sin(w D t) / [ z 22 z cos(w D t)+1] |
cos(w t) | s /(s 2 + w 2) | z [ z cos(w D t)] / [ z 22 z cos(w D t)+1] |
exp(- at) sin(w t) | w /[(s 2 + a 2) + w 2] | z exp(aD t)sin(w D t) / [ z 22 z exp(aD t)* *cos(w D t)+exp(2 a D t)] |
exp(- at) cos(w t) | (s + a)/[(s 2 + a 2) + w 2] | z 2 z exp( a D t)* *cos(w D t)/ [ z 22 z exp( a D t)* *cos(w D t)+exp(2 a D t)] |
2.1.2
x (t) | |
1. k x (t) | k X (z) |
2. x 1(t) + x 2(t) | X 1(z) + X 2(z) |
3. x (t +D t) | z X (z) z x (0) |
4. t x (t) | D t z d X (z) / d z |
5. exp( at) x (t) | X [ z exp(at)] |
6. x (0), | lim X (z) z ¥ |
7. x (¥), | lim(z 1) X (z) z 1, (z 1) X (z) - ê z ê= 1 z - |
.
z - z - X (z) Y (z)
. (2.1.7)
2.1.2. (. . 2.1.4) G 0(s) (. 2.1.1) G O(s) = 1/ s (s +1), . 2.1.7.
. 2.1.7
x (t) = d(t) ( ) D t = 1 c.
G (s) = G 0(s) G O(s) = [1exp( s D t)] / s 2 (s + 1) =
= [1exp( s D t)] [(1/ s 2) + (1/ s) + 1/(s +1)]. (2.1.8)
2.1.1 z - (2.1.8),
G (z) = Z {[1exp( s D t)] [(1/ s 2) (1/ s) + 1/(s +1)]} =
= (1 z -1) Z {[(1/ s 2) (1/ s) + 1/(s +1)]} = (2.1.9)
= =
= .
D t = 1,
G (z) = . (2.1.10)
|
|
, X (z) = 1, Y (z) = G (z). (2.1.10)
,
Y (z) = 0,3678 z -1 + 0,7675 z -2 + 0,9145 z -3 + (2.1.11)
, ( ) :
y (0) = 0; y (1) = 0, 3678; y (2) = 0, 7675; y (3) = 0, 9145.
.
. 2.1.8 ( , ).
. 2.1.8
(z) = . (2.1.12)
2.1.3. G(z) . 2.1.8 (2.1.10), 2.1.2. (z) , , .. x (t) = q (t) ( ).
(2.1.10) (2.1.12),
(z) = . (2.1.13)
z - X(z) = = z /(z 1),
.
, 2.1.3,
Y (z) = 0,3678 z -1 + z -2 + 1,4 z -3 +1,4 z -4 + 1,147 z -5 + (2.1.14)
, ( ) :
y (0) = 0; y (1) = 0, 3678; y (2) = 1; y (3) = 1,4; y (4) = 1,4; y (5) = 1,147.
2.2. .
, (s) s - (. . 1.3.1 . 21).
Z - s -
z = exp(s D t) = exp[(s + jw)D t ]. (2.2.1)
,
½ z ½= exp(s D t) arg z = w D t. (2.2.2)
s - s < 0, 0 £½ z ½£ 1. (2.2.1) s - z -, s -.
, (z) z- .
2.2.1. , . 2.1.8,
G (z) = , (2.2.3)
a K .
(z) 1+ G (z),
q (z) = 1+ G (z) = z 2[1,36780,3678 K ]z +0,3678+0,2644 K = 0.
K = 1
q (z) = z 2 z +0,6322 =
= (z 0,50 + j 0,6182)(z 0,50 j 0,6182) = 0.
, .
K = 10,
q (z) = z 2 + 2,310 z +3,012 =
= (z + 1,155 + j 1,295)(z + 1,155 j 1,295) = 0,
.
, , s -.
2.3. .
- (. 1.6.6 . 42)
. (2.3.1)
, . (. 1.2.5 . 17)
. (2.3.2)
(2.3.2) z -,
. (2.3.3)
, (2.3.4)
u (k D t) t = k D t. (2.3.4) z -,
, . (2.3.5)
, -
|
|
. (2.3.6)
(2.3.6) z - , -
u (k) = K 1 e (k) + K 2 [ u (k 1) + D t e (k)] + [ e (k) e (k 1)] =
= K 2 u (k 1) + [ K 1 + K 2 D t + ] e (k) e (k 1). (2.3.7)
(2.3.7) .
2.4. .
. , .. , . , .
.
,
B d2 y (t) /d t 2 + C d y (t) /d t + D y (t) = x (t). (2.4.1)
y (t) d y (t)/d t.
y 1(t) = y (t), (2.4.2)
y 2(t) = d y (t)/d t.
(2.1.1)
d y 1(t) /d t = 0 y 1(t) + y 2(t), (2.4.3)
d y 2(t) /d t = (D / B) y 1(t) (C/B) y 2(t) + (1/ B) x (t).
. , , , .
x ¢1 = a 11 x 1 + a 12 x 2 + + a 1n x n + b 11 u 1 + b 12 u 2 ++ b 1m u m,
x ¢2 = a 21 x 1 + a 22 x 2 + + a 2n x n + b 21 u 1 + b 22 u 2 ++ b 2m u m,
.,
x ¢n = a n1 x 1 + a n2 x 2 + + a nn x n + b n1 u 1 + b n2 u 2 ++ b nm u m,
x ¢ = d x (t)/d t.
,
, (2.4.4)
- x u, A = [ a nm] B = [ b nm].
y = Cx + Du, (2.4.5)
y , -.
2.4.1. RLC , . 2.4.1.
. 2.4.1
x 1 = uC, x 2 = iL. , ,
d x 1(t) /d t = 0 x 1(t) x 2(t) + u (t), (2.4.5)
d x 2(t) /d t = x 1(t) x 2(t).
y 1(t) = uR (t) = R x 2(t). (2.4.6)
,
, y (t) = [0 R ] x (t). (2.4.7)