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Sbe final exam jan17 - solved-converted
- 1. Page1/9
DYNAMIC CONTROL SYSTEMS
(SBE_305A)
Final Exam
Spring 2015
Cairo University
Faculty of Engineering
Systemsand Biomedical Engineering Dept.
Answer ONLY FIVE Questions (Full Mark 75 points)____ Time Allowed : 3 Hours
Question 1 (15 points):
a) Using block diagram reduction:
Now ๐ฎ ๐(๐) =
๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)๐ฏ ๐(๐)
๐ฎ ๐(๐) =
๐
๐ฎ ๐(๐)
๐ฎ ๐(๐) =
๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)๐ฏ ๐(๐)
๐ฎ ๐(๐) =
๐ฎ ๐(๐)๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)๐ฎ ๐(๐)๐ฏ ๐(๐)
=
๐ฎ ๐(๐)โ
๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)๐ฏ ๐(๐)
๐+๐ฎ ๐(๐)โ
๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)๐ฏ ๐(๐)
โ๐ฏ ๐(๐)
=
๐ฎ ๐(๐)๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)๐ฏ ๐(๐)+๐ฎ ๐(๐)๐ฎ ๐(๐)๐ฏ ๐(๐)
=
๐ฎ ๐(๐)๐ฎ ๐(๐)
๐+๐ฎ ๐(๐)[๐ฏ ๐(๐)+๐ฎ ๐(๐)๐ฏ ๐(๐)]
๐ฎ ๐(๐) = ๐ + ๐ฎ ๐(๐) = ๐ +
๐
๐ฎ ๐(๐)
=
๐ + ๐ฎ ๐(๐)
๐ฎ ๐(๐)
โด ๐ป(๐) =
๐ช(๐)
๐น(๐)
= ๐ฎ ๐(๐)๐ฎ ๐(๐)๐ฎ ๐(๐) =
๐ฎ ๐(๐)๐ฎ ๐(๐)
๐ + ๐ฎ ๐(๐)[๐ฏ ๐(๐) + ๐ฎ ๐(๐)๐ฏ ๐(๐)]
๐ + ๐ฎ ๐(๐)
๐ฎ ๐(๐)
๐ฎ ๐(๐)
๐ + ๐ฎ ๐(๐)๐ฏ ๐(๐)
R(s) C(s)
G1(s) G2(s) G4(s)
H2(s)
H1(s)
+ + +
+--
G1(s) G2(s) G4(s)
G5(s)
H1(s)
H2(s)
R(s) C(s)
G5(s)
G1(s) G6(s) G4(s)
H1(s)
R(s) C(s)
G7(s)
G5(s)
G4(s)
R(s)
C(s)
G7(s) G8(s) (s)4G
R(s)
C(s)
- 2. Page2/9
=
๐ฎ ๐(๐)๐ฎ ๐(๐)[๐ + ๐ฎ ๐(๐)]
[๐ + ๐ฎ ๐(๐)๐ฏ ๐(๐)]{๐ + ๐ฎ ๐(๐)[๐ฏ ๐(๐) + ๐ฎ ๐(๐)๐ฏ ๐(๐)]}
๐ป(๐) =
๐ช(๐)
๐น(๐)
=
โ ๐ท ๐โ๐
โ
=
๐ท ๐โ ๐+๐ท ๐โ ๐
โ
๐ท ๐ = ๐ ๐ท ๐ =
๐
๐ ๐
๐ณ ๐ = ๐ณ ๐ = โ๐ ๐
๐ณ ๐ = ๐ณ ๐ = โ
๐
๐
โด โ= ๐ โ (๐ณ ๐ + ๐ณ ๐ + ๐ณ ๐ + ๐ณ ๐) = ๐ + (๐ ๐
+
๐
๐
+ ๐ ๐
+
๐
๐
) = ๐ +
๐๐ ๐
+ ๐
๐
=
๐๐ ๐
+ ๐ + ๐
๐
โด ๐ป(๐) = (๐ +
๐
๐ ๐
) โ
๐
๐๐ ๐ + ๐ + ๐
=
๐(๐ ๐
+ ๐)
๐ ๐(๐๐ ๐ + ๐ + ๐)
=
๐ ๐
+ ๐
๐(๐๐ ๐ + ๐ + ๐)
c) Let ๐ฎ ๐(๐) = ๐ ๐
๐ฎ ๐(๐) =
๐
๐
๐ฎ ๐(๐) = ๐ฎ ๐(๐) + ๐ฎ ๐(๐)
๐ฎ ๐(๐) = ๐๐๐๐
๐๐๐๐(๐ฎ ๐(๐), ๐)
๐ฎ ๐(๐) = ๐ฎ ๐(๐) โ
๐
๐
๐ป(๐) = ๐๐๐๐
๐๐๐๐(๐ฎ ๐(๐), ๐)
Thus, the Matlab code is given by:
- 3. Page3/9
>>num1=[1 0 0]
>>den1=[1]
>>G1=tf(num1,den1)
>>num2=[1]
>>den1=[1 0]
>>G2=tf(num2,den2)
>>G3=G1+G2
>>G4=feedback(G3,[1])
>>G5= G4*G2
>>num6=[1 0]
>>den6=[1]
>>G6=tf(num6,den6)
>>T=feedback(G5,G6)
Question 2 (15 points):
a) The system poles are given by: s = -10, s = -3 ยฑ j
b) The damping ratio and natural frequency of the dominant poles can be obtained by equating the
second factor of the denominator with zero. This takes the form:
๐ ๐
+ ๐๐ป๐ ๐ + ๐ ๐
๐
= ๐
โด ๐๐ป๐ ๐ = ๐ ===> ๐ป๐ ๐ = ๐
๐ ๐
๐
= ๐๐ ===> ๐ ๐ = โ๐๐ ๐๐๐
/๐
โด ๐ปโ๐๐ = ๐ ===> ๐ป =
๐
โ๐๐
= ๐. ๐๐๐
c) For the unit impulse response R(s) = 1. Thus
๐(๐) =
๐๐ + ๐
(๐ + ๐๐)(๐ ๐ + ๐๐ + ๐๐)
=
๐๐๐ + ๐๐
๐๐(๐ ๐ + ๐๐ + ๐๐)
โ
๐๐
๐๐(๐ + ๐๐)
=
๐๐(๐ + ๐) โ ๐๐
๐๐[(๐ + ๐) ๐ + ๐]
โ
๐๐
๐๐(๐ + ๐๐)
โด ๐(๐) = ๐. ๐๐๐โ๐๐
โ ๐๐จ๐ฌ ๐ โ ๐. ๐๐๐โ๐๐
โ ๐ฌ๐ข๐ง ๐ โ ๐. ๐๐๐โ๐๐๐
= ๐. ๐๐๐๐๐๐โ๐๐
โ ๐๐จ๐ฌ(๐ + ๐๐. ๐ยฐ) โ ๐. ๐๐๐โ๐๐๐
d) For the unit step response ๐น(๐) =
๐
๐ฌ
. Thus
๐(๐) =
๐๐ + ๐
๐(๐ + ๐๐)(๐ ๐ + ๐๐ + ๐๐)
=
๐
๐๐๐๐
+
๐๐
๐๐๐(๐ + ๐๐)
+
๐๐ โ ๐๐๐
๐๐๐(๐ ๐ + ๐๐ + ๐๐)
=
๐
๐๐๐๐
+
๐๐
๐๐๐(๐ + ๐๐)
โ
๐๐(๐ + ๐) โ ๐๐๐
๐๐๐[(๐ + ๐) ๐ + ๐]
โด ๐(๐) = ๐. ๐๐ + ๐. ๐๐๐๐โ๐๐๐
โ ๐. ๐๐๐๐โ๐๐
โ ๐๐จ๐ฌ ๐ + ๐. ๐๐๐๐โ๐๐
โ ๐ฌ๐ข๐ง ๐
= ๐. ๐๐ + ๐. ๐๐๐๐โ๐๐๐
โ ๐. ๐๐๐๐๐๐โ๐๐
โ ๐๐จ๐ฌ(๐ + ๐๐. ๐ยฐ)
e) ess(โ) = 1 โ T(0) = ๐ โ
๐
๐๐ร๐๐
= ๐. ๐๐ = ๐๐%
- 4. Page4/9
Question 3 (15 points):
a) Let the driving pressure be given by Pd = P1 โ P2
โด ๐ธ = ๐ฒโ๐ท ๐
โด โ๐ธ =
๐
๐ธ
๐
๐ท ๐
โ๐ท ๐
=
๐ฒ
๐โ๐ท ๐
โ๐ท ๐
=
๐ฒ
๐โ๐ท ๐ โ ๐ท ๐
โ(๐ท ๐ โ ๐ท ๐)
Now if Pd = P1 โ P2 = 0, then in that limiting case the slope of the Q โ (P1 โ P2) characteristic
approaches infinity. So, for an infinitesimal change in P1 โ P2 the change in Q grows beyond all
limits.
b) ๐บ ๐ฎ
๐ป
=
๐
๐+๐ฎ(๐)๐ฏ(๐)
=
๐
๐+๐ฎ(๐)
=
๐
๐+
๐๐๐
๐ ๐+๐๐+๐๐๐
=
๐ ๐+๐๐+๐๐๐
๐ ๐+๐๐+๐๐๐
๐บ ๐ฏ
๐ป
=
โ ๐ฎ( ๐) ๐ฏ(๐)
๐ + ๐ฎ( ๐) ๐ฏ(๐)
= โ
๐๐๐ ร ๐
๐ ๐ + ๐๐ + ๐๐๐
โ
๐ ๐ + ๐๐ + ๐๐๐
๐ ๐ + ๐๐ + ๐๐๐
= โ
๐๐๐
๐ ๐ + ๐๐ + ๐๐๐
c) ๐บ ๐ฎ
๐ป
=
๐
๐+๐ฎ(๐)๐ฏ(๐)
=
๐
๐+
๐๐๐
๐ ๐+๐๐+๐๐๐
โ
๐
๐
=
๐( ๐ ๐
+๐๐+๐๐๐)
๐( ๐ ๐+๐๐+๐๐๐)+๐๐๐
=
๐ ๐
+๐๐ ๐
+๐๐๐๐
๐ ๐+๐๐ ๐+๐๐๐๐+๐๐๐
๐บ ๐ฏ
๐ป
=
โ ๐ฎ( ๐) ๐ฏ(๐)
๐+๐ฎ( ๐) ๐ฏ(๐)
= โ ๐๐๐
๐ ๐+๐๐+๐๐๐
โ ๐
๐
โ ๐ ๐+๐๐ ๐+๐๐๐๐
๐ ๐+๐๐ ๐+๐๐๐๐+๐๐๐
= โ๐๐๐
๐ ๐+๐๐ ๐+๐๐๐๐+๐๐๐
d) The circuit becomes
Y1(s) = R1ยทI(s)
๐ฐ(๐) =
๐ผ ๐(๐)
๐(๐)
Z(s)= Z1(s)+ Z2(s)
Z1(s)= R1+sL1
- 5. Page5/9
๐ ๐(๐) =
๐น ๐(๐น ๐+
๐
๐๐ช
)
๐น ๐+๐น ๐+
๐
๐๐ช
=
๐น ๐(๐๐ช๐น ๐+๐)
๐๐ช(๐น ๐+๐น ๐)+๐
โด ๐(๐) = ๐น ๐ + ๐๐ณ ๐ +
๐น ๐( ๐๐ช๐น ๐ + ๐)
๐๐ช( ๐น ๐ + ๐น ๐) + ๐
=
[ ๐๐ช( ๐น ๐ + ๐น ๐) + ๐](๐น ๐ + ๐๐ณ ๐) + ๐น ๐( ๐๐ช๐น ๐ + ๐)
๐๐ช( ๐น ๐ + ๐น ๐) + ๐
=
๐ ๐
๐ช๐ณ ๐(๐น ๐ + ๐น ๐) + ๐[๐ช(๐น ๐ + ๐น ๐)๐น ๐ + ๐ณ ๐ + ๐ช๐น ๐ ๐น ๐] + (๐น ๐ + ๐น ๐)
๐๐ช(๐น ๐ + ๐น ๐) + ๐
โด ๐ฐ(๐)
=
๐๐ช(๐น ๐ + ๐น ๐) + ๐
๐ ๐ ๐ช๐ณ ๐(๐น ๐ + ๐น ๐) + ๐[๐ช(๐น ๐ + ๐น ๐)๐น ๐ + ๐ณ ๐ + ๐ช๐น ๐ ๐น ๐] + (๐น ๐ + ๐น ๐)
๐ผ ๐(๐)
โด
๐ ๐(๐)
๐ผ ๐(๐)
=
๐น ๐[๐๐ช(๐น ๐ + ๐น ๐) + ๐]
๐ ๐ ๐ช๐ณ ๐(๐น ๐ + ๐น ๐) + ๐[๐ช(๐น ๐ + ๐น ๐)๐น ๐ + ๐ณ ๐ + ๐ช๐น ๐ ๐น ๐] + (๐น ๐ + ๐น ๐)
Question 4 (15 points):
a) We can obtain the state space model from the transfer function as follows:
U(s) +
Let ๐บ2(๐ ) = ๐บ1(๐ ) โ
1
๐
Now ๐บ1(๐ ) = ๐ +
๐
๐
=
๐๐ +๐
๐
โด ๐บ2(๐ ) =
๐๐ + ๐
๐ 2
โด ๐บ(๐ ) =
๐(๐ )
๐(๐ )
=
๐บ2(๐ )
1 + ๐บ2(๐ )
=
๐๐ +๐
๐ 2
1 +
๐๐ +๐
๐ 2
=
๐๐ + ๐
๐ 2 + ๐๐ + ๐
This is of the form
๐บ(๐ ) =
๐ ๐ ๐ 2
+ ๐1 ๐ + ๐2
๐ 2 + ๐1 ๐ + ๐2
In that case the state model is given by:
๐ = [
0 1
โ๐2 โ๐1
] = [
0 1
โ๐ โ๐
]
G1(s)
๐
๐
_
Y(s)
- 6. Page6/9
๐ = ๐ท = [
๐ฝ1
๐ฝ2
] = ๐ โ ๐๐โฒ
= [
๐1
๐2
] โ [
๐1 0
๐2 ๐1
] [
๐ ๐
๐ฝ1
]
๐ = [1 0] ๐ = ๐ ๐ = 0
๐ฝ1 = ๐1 โ ๐1 ๐ ๐ = ๐
๐ฝ2 = ๐2 โ ๐2 ๐ ๐ โ ๐1 ๐ฝ1 = ๐ โ ๐2
b) The system eigenvalues can be computed from:
|๐๐ โ ๐| = |
๐ โ1
๐ ๐ + ๐
| = ๐(๐ + ๐) + ๐ = ๐2
+ ๐๐ + ๐ = 0
โด ๐ =
โ๐ ยฑ โ๐2 โ 4๐
2
c) The transfer function can be derived from the state model as follows:
๐บ(๐ ) = ๐(๐ฌ๐ โ ๐)โ๐
๐ + ๐
Now ๐ฌ๐ โ ๐ = [
๐ โ1
๐ ๐ + ๐
]
(๐ฌ๐ โ ๐)โ1
=
1
๐ 2+๐๐ +๐
[
๐ + ๐ 1
โ๐ ๐
]
โด ๐บ(๐ ) = [1 0]
1
๐ 2 + ๐๐ + ๐
[
๐ + ๐ 1
โ๐ ๐
] [
๐
๐ โ ๐2] =
๐๐ + ๐
๐ 2 + ๐๐ + ๐
d) The system poles are the same as the eigenvalues.
e) If a = 2 & b = 4, then:
๐ = [
0 1
โ4 โ2
] ๐ = [
๐
๐ โ ๐2] = [
2
4 โ 4
] = [
2
0
] ๐ = [1 0] ๐ท = 0
The transfer function becomes:
๐บ(๐ ) =
2๐ + 4
๐ 2 + 2๐ + 4
f) >>A=[0 1;-4 -2]
>>B=[2;0]
>>C=[1 0]
>>D=[]
>>S=ss(A,B,C,D)
>>tf(S)
- 7. Page7/9
Question 5 (15 points):
a) ๐บ(๐ ) =
3๐ +2
๐ 2+7๐ +12
=
๐ ๐ ๐ 2+๐1 ๐ +๐2
๐ 2+๐1 ๐ +๐2
โด ๐1 = 7 ๐2 = 12 ๐1 = 2 ๐2 = 2 ๐ ๐ = 0
๐ = [
0 1
โ๐2 โ๐1
] = [
0 1
โ12 โ7
] ๐ = [1 0] ๐ = ๐ ๐ = 0 = ๐ฝ ๐
๐ = ๐ = ๐ โ ๐๐โฒ
โด [
๐ฝ1
๐ฝ2
] = [
๐1
๐2
] โ [
๐1 0
๐2 ๐1
] [
๐ฝ ๐
๐ฝ1
] = [
3
2
] โ [
7 0
12 7
] [
0
๐ฝ1
]
โด ๐ฝ1 = 3 โ 7 ร 0 โ 0 ร ๐ฝ1 = 3
๐ฝ2 = 2 โ 12 ร 0 โ 7๐ฝ1 = 2 โ 7 ร 3 = โ19
โด ๐ = [
3
โ19
]
b) The controllable state model is given by:
๐ ๐ = [
0 1
โ๐2 โ๐1
] = [
0 1
โ12 โ7
]
๐ ๐ = [
0
1
]
๐ ๐ = [ ๐2 โ ๐2 ๐ ๐| ๐1 โ ๐1 ๐ ๐] = [2 โ 12 ร 0|3 โ 7 ร 0] = [2 3]
๐ ๐ = ๐ ๐ = 0
c) The observable state model is given by:
๐ ๐ = ๐ ๐
๐
= [
0 โ12
1 โ7
]
๐ ๐ = ๐ ๐
๐
= [
2
3
] ๐ ๐ = ๐ ๐
๐
= [0 1] ๐ ๐ = ๐ ๐ = 0
d) ๐บ(๐ ) =
3๐ +2
๐ 2+7๐ +12
=
3๐ +2
(๐ +3)(๐ +4)
=
10
๐ +4
โ
7
๐ +3
=
๐1
๐ +๐1
+
๐2
๐ +๐2
๐ = [
โ ๐1 0
0 โ ๐2
] = [
โ4 0
0 โ3
] ๐ = [
1
1
] ๐ = [ ๐1 ๐2] ๐ = ๐ ๐ = 0
e) >>num=[3 2]
- 8. Page8/9
>>den=[1 7 12]
>>[A,B,C,D]=tf2ss(num,den)
Question 6 (15 points):
a) ๐บ(๐ ) =
๐ 2+4๐ +2
(๐ +1)(๐ 2+4๐ +4)
=
๐ 2+4๐ +2
(๐ +2)2(๐ +1)
=
๐ 2+4๐ +2
(๐ +๐1)2(๐ +๐3)
=
2
(๐ +2)2
+
2
๐ +2
โ
1
๐ +1
=
๐1
( ๐ +๐1)
2 +
๐2
๐ +๐1
+
๐3
๐ +๐3
โด ๐ = [
โ ๐1 1 0
0 โ ๐1 0
0 0 โ ๐3
] = [
โ2 1 0
0 โ2 0
0 0 โ1
] ๐ = [
0
1
1
]
๐ = [ ๐1 ๐2 ๐3] = [2 2 โ1] ๐ = ๐ ๐ = 0
b) We first compute the eigenvalues as follows:
|๐๐ โ ๐| = |
๐ โ1
3 ๐ + 4
| = ๐(๐ + 4) + 3 = ๐2
+ 4๐ + 3 = (๐ + 1)(๐ + 3) = 0 ===> ๐1 = โ1
๐2 = โ3
Then we construct the transformation matrix P such that x = Pz, where z is an auxiliary vector.
๐ = [
1 1
๐1 ๐2
] = [
1 1
โ1 โ3
]
The state model becomes:
๐ณฬ = ๐โ๐
๐๐๐ณ + ๐โ๐
๐๐ข
๐ฆ = ๐๐๐ณ + ๐๐ข
Now ๐โ๐
๐๐ = [
โ ๐1 0
0 โ ๐2
] = [
โ1 0
0 โ3
] ๐โ๐
๐ =
1
2
[
1
โ1
] ๐๐ = [1 1] ๐ = 0
c) ๐(๐ฌ) = ๐(๐ฌ๐ โ ๐)โ1
๐ + ๐ = ๐(๐ฌ๐ โ ๐)โ1
๐
๐ฌ๐ โ ๐ = [
๐ โ1
2 ๐ + 4
]
โด ๐(๐ฌ) =
1
๐ 2 + 4๐ + 2
[
1 ๐ + 4
๐ โ2
]
d) >>A=[0 1;-2 -4]
>>B=[0 1;1 0]
>>C=[1 0;0 1]
>>D=[]