Aswan University
Fourth Year
Faculty of Engineering
Automatic Control (II) Course
Electrical Engineering Department
First Semester
Computers and Systems Section
Sheet No. 4
Sheet No. 4
1- Plot a Bode diagram for the following transfer functions:
25
a. 𝐺(𝑠) =
𝑠 2 +4𝑠+25
9(𝑠 2 +0.2𝑠+1)
b. 𝐺(𝑠) =
𝑠(𝑠 2 +1.2𝑠+9)
2- Obtain the phase and gain margin of the system shown in below for the two cases where K=10 and
K=100.
R(s) C(s)
K
+
- s ( s 1)( s 5 )
3- For the figure shown in below, determine the gain K such that the phase margin is 50° . What is the
gain margin in this case?
C(s)
R(s) K (s 2)
+
- s2
4- Consider the unity-feedback control system whose open-loop transfer function is:
𝑎𝑠 + 1
𝐺(𝑠) =
𝑠2
- Determine the value of a so that the phase margin is 45° .
5- Consider the unity-feedback system with the open-loop transfer function:
10
𝐺(𝑠) =
(𝑠 + 1)
- Obtain the steady-state output of the system when it is subjected to each of the following
inputs:
a. 𝑟(𝑡) = sin(𝑡 + 30)
b. 𝑟(𝑡) = 2𝑐𝑜𝑠(2𝑡 − 45)
c. 𝑟(𝑡) = sin(𝑡 + 30) − 2cos(2𝑡 − 45)
6- Given:
𝜔𝑛2
𝐺(𝑠) =
(𝑠 2 + 2𝜁𝜔𝑛 𝑠 + 𝜔𝑛2 )
1
Show that: |𝐺(𝑗𝜔𝑛 )| =
2𝜁
With my best wishes Dr. Mountasser M. Mohamed
Aswan University
Fourth Year
Faculty of Engineering
Automatic Control (II) Course
Electrical Engineering Department
First Semester
Computers and Systems Section
Sheet No. 4
7- Draw a Bode diagram of the open-loop transfer function G(s). Determine the phase margin and
gain margin.
a.
R(s) C(s)
25
+
- s ( s 1 )( s 10 )
G(s)
b.
R(s) C(s)
20( s 1)
+ s ( s 2 s 10)( s 5)
2
-
G(s)
8- Consider a unity-feedback control system with the open-loop transfer function:
𝐾
𝐺(𝑠) =
𝑠(𝑠 2 + 𝑠 + 4)
- Determine the value of the gain K such that the phase margin is 50° . What is the gain
margin with this gain K?
9- Draw a Bode diagram of the open-loop transfer function, and determine the value of the gain K
such that the phase margin is 50° . What is the gain margin with this gain K?
C(s)
R(s) 20 K ( s 0 . 1)
+
- s ( s 1)( s 0 . 5 )
G(s)
With my best wishes Dr. Mountasser M. Mohamed