Cork Institute of Technology
Bachelor of Engineering (Honours) in Electronic Engineering
 Stage 3
(EELXE_8_Y3)
Autumn 2008
CONTROL SYSTEMS
(Time: 3 Hours)
INSTRUCTIONS:
Answer any FOUR questions.
Each question is worth 25 marks.
You MUST include a list of all MATLAB commands or Simulink diagrams used to
answer a question. Marks will be lost if you fail to do this.
Examiners: Dr. T O' Mahony
Prof. G. Hurley
Dr. S. Foley
Q1. (a) In your own words clearly explain the difference between an openloop control
system and a closedloop control system. Include a block diagram illustrating the
difference between an openloop system and a closedloop system. Give one
example of an openloop system and one example of a closedloop system.
[5 marks]
(b) The thermal response of a domestic central heating system is defined by the
differential equation () 0.003 ( ) 0.02 ( )
dT t Tt Ut
dt
+=
where T(t) is the building
temperature and U(t) is the input signal that switches on/off the electric/gas boiler.
Apply the Laplace Transform to determine a transfer function for this system. What
is the gain of the domestic heating system and what is the timeconstant?
[5 marks]
(c) Calculate the closedloop transfer function for the system illustrated in Figure Q1(c)
for a value of controller gain K = 10. Is the closedloop system stable for this value
of gain? Generate the response to a unit step input and measure (i) the steadystate
error and (ii) the percentage overshoot. How would you eliminate the steadystate
error in this case?
Plant
Controlle
R(s) U(s)
+

Y(s)
K
2
0.6
0.4 0.4ss++
Figure Q1(c)
[15 marks]
Q2. (a) Consider the frequency responses illustrated in Figure Q2(a) and Figure Q2(b).
Figure Q2(a)
Document information
Uploaded by:
lalchand
Views: 1601
Downloads :
0
Address:
Computer science
University:
Aligarh Muslim University
Subject:
Control Systems
Upload date:
30/03/2013