Daffodil International University
Institutional Repository
Proceedings of ICTERC
ICTERC 2013
2013-01-21
Teaching Control Systems Course for
Electrical Engineering Students in
Cognitive Domain
Bhuyan, Muhibul Haque
http://hdl.handle.net/20.500.11948/896
Downloaded from http://dspace.library.daffodilvarsity.edu.bd, Copyright Daffodil International University Library
International Conference on Tertiary Education (ICTERC 2013) Daffodil International University, Dhaka, Bangladesh 19-21 January 2013.
Teaching Control Systems Course for Electrical
Engineering Students in Cognitive Domain
Muhibul Haque Bhuyan
Department of Electrical and Electronic Engineering
Green University of Bangladesh, Dhaka
E-mail: [email protected]
Abstract: Control systems course is a very important
core course for the students of undergraduate program
of electrical and electronic engineering. All types of
industries require control system engineers whose
efficient operation and controlling of the machineries
produce optimum output. Therefore, ‘Control Systems’
course has real life applications in the fields of
electrical and electronic engineering and hence this
course needs to be taught efficiently so that students can
apply the knowledge earned from this course in solving
their practical problems. Skills in the cognitive domain
of Bloom's Taxonomy revolve around knowledge,
comprehension, and critical thinking of a particular
topic. This makes teaching and learning more effective
and efficient. In this paper, the teaching method of
‘Control Systems’ course for undergraduate electrical
and electronic engineering students in the cognitive
domain has been described.
Index Terms : Control Systems, Teaching Methods,
Bloom’s Taxonomy, Cognitive Domain.
I. INTRODUCTION
Engineering is concerned with understanding
and controlling the materials and forces of nature
for the benefit of humankind. Control system
engineers are concerned with understanding and
controlling segments of their environment, often
called systems, to provide useful economic
products for the society. Effective system control
requires that the systems be understood and
modelled perfectly [1]. Control systems are used to
achieve increased productivity and improved
performance of a device or system with high
precision [2]. All types of industries, such as,
automobile
[3-4],
biomedical
[5-7],
telecommunication [8], robotics and automation
[9], motion control [10] etc. require various types
of control operations for optimum production and
hence they need „Control Systems‟ engineers.
Therefore, „Control Systems‟ course is a very
important and useful course in the curriculum of
the undergraduate program of electrical and
electronic engineering (EEE). This course always
occupies the core position in EEE curriculum.
Therefore, this course is designed to teach the
students various theories on designing and
simulating the various types of „Control Systems‟
and also to operate them for uninterrupted output
of the industries. So, this course should be
designed and taught in such a way so that the
students be prepared to master various rules and
theories for designing the real-time „Control
Systems‟ engineering problems [11].
Any engineering program should be mandated
by an accreditation agency (such as, in USA it is
„Engineering Accreditation Commission of the
Accreditation Board for Engineering and
Technology, EAC/ABET) and the accreditation of
an engineering program will be judged with respect
to define program outcomes. Each program must
have an assessment process for continuous
improvement with documented results. Any well
thought course required for an engineering degree
should be able to contribute towards fulfilling the
program educational objectives, which are
mandated by the ABET criteria 2000 [12].
Currently, the education system is undergoing
rapid changes. Various new methods are
introduced and used. Further, it makes teaching
more effective and learning is highly significant.
An important goal of the undergraduate curriculum
in engineering is to develop the integration, design,
and evaluation capabilities of the student. As
shown in Fig. 1, Bloom in 1956 characterized the
six cognitive levels in the hierarchy: Knowledge 
Comprehension  Application  Analysis 
Synthesis  Evaluation. The cognitive skills at the
highest level are synthesis and evaluation, which
rely on comprehension, application, and analysis
capabilities in the knowledge domain, and are
consequently the most difficult and challenging to
teach. However, to prepare undergraduate courses
to be effective in designing engineering systems in
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International Conference on Tertiary Education (ICTERC 2013) Daffodil International University, Dhaka, Bangladesh 19-21 January 2013.
the industry, it is important to ensure an adequate
coverage of these higher-level skills, rather than
limiting their education to one based on just
knowledge, comprehension, application, and
analysis [13].
Fig. 1 Levels in Cognitive Domain
Before mentioned that, in engineering education
there is a shift in emphasis from professional skills
to process skills [14]. These skills include problem
analysis and problem solving, project management
and leadership, analytical skills and critical
thinking, dissemination and communication,
interdisciplinary
competencies,
intercultural
communication, innovation and creativity, and
social abilities [15].
In this paper, teaching method of the „Control
Systems‟ course for the undergraduate students of
the electrical and electronic engineering program in
cognitive domain has been described with an
example.
CONSTRAINTS OF TEACHING CONTROL
SYSTEMS
Learning is an activity that leads to change and
control of what is taught, while teaching is a
practical activity or action,
be intentional and
conscious to assist learning. Teachers should
act an essential role as a facilitator in the process of
teaching and learning.
We, as human beings, are born with certain
limitations. Our memory is limited and we forget
things very easily. If we learn and know certain
things, our memory of those things decays almost
exponentially unless the things are repeated. Thus,
it does not matter what we teach, students will
either forget or the materials will become obsolete,
even before they graduate. Therefore, we should
II.
teach things in such a way to develop student‟s
certain abilities.
For example, we can rate the student‟s
knowledge of the subject materials as zero at the
start of the class. On the day of final, students
should have the highest knowledge of the subject
materials and we can rate the student‟s knowledge
as logic 1 at the start of the exam. But, after one or
two years, that knowledge would decay almost to
logic 0, the same logic value as the start. The logic
knowledge pattern can be described as {0 1 0}
[16].
On the other hand, a student who never attended
a class and earned no knowledge, his logic states of
the knowledge can be described as {0 0 0}. But
there is difference between a student who started
with 0 knowledge, gained the highest knowledge
(logic 1) and then forgot the knowledge (logic 0)
and another student who started with 0 knowledge,
did not gain any knowledge (logic 0) and no
knowledge to forget (logic 0) [16]. Because,
students gain some experience through this
learning process. Hence teaching and learning
process of the „Control Systems‟ course should be
conducted in such a way so that the students gain
some experiences in designing and analyzing the
control systems after the end of the course.
III. DESIGNING CONTROL SYSTEMS COURSE
One of the desired attributes of an engineer [1719] in the global marketplace in the new
knowledge economy is that an engineer should
have good understanding of engineering
fundamentals and design/manufacturing processes.
Therefore, any undergraduate course should be
designed in such a way so that the students are able
to design the systems both analytically and
numerically. Keeping this in mind, „Control
Systems‟ course is designed in the following way.
I. Course Contents
This gives the complete description of the
course. The course contents should be designed in
such a way so that the students get a deep
knowledge and develop their skills to apply the
knowledge in their fields and course objectives are
achieved. Incorporation of too many topics in the
course may impede the students‟ learning
objectives. So, the optimal contents for „Control
Systems‟ course are set as follows:
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International Conference on Tertiary Education (ICTERC 2013) Daffodil International University, Dhaka, Bangladesh 19-21 January 2013.
Introduction to Control Systems: Definition of
control systems, examples of modern control
systems, mathematical modelling and control of
linear feedback systems: Transfer Functions of
Systems with Op-Amps, Electro-mechanical
Systems, Modeling of DC Motors, Design of a
Speed Control System, Design of a Position
Control System, Signal Flow Graphs, Mason's
Rule, Stability of Linear Feedback Systems: The
Concept of Stability, BIBO Stability, RouthHurwitz Stability Criterion, Design of Stable
Systems, Performance of Feedback Control
Systems: Design Requirements Based on TimeDomain Performance Specifications, The Location
of Poles and the Transient Response. The RootLocus Method: The Rules of the Root-Locus
Method, Analysis and Design using the RootLocus Method, Parameter Design, Sensitivity and
Frequency Response. The Nyquist Stability
Criterion: Contour Mapping in the s-plane, The
Nyquist Criterion. Frequency Response Methods:
The Bode Plot, Performance Specifications in the
Frequency Domain, Magnitude and Phase Plots,
Design of Feedback Systems Using Frequency
Response Methods. Introduction to Programmable
Logic Controller (PLC).
J. Course Objectives
Learning objectives or instructional objectives
are statements of what students should be able to
do if they have acquired the knowledge and skills
the course is supposed to teach them. The
objectives of „Control Systems‟ course have been
set as follows:
1. To know the basic features, configurations and
application of control systems.
2. To know various terminologies and definitions
for the control systems.
3. To learn how to find a mathematical model of
electrical, mechanical and electro-mechanical
systems
4. To know how to find time response from the
transfer function
5. To find the transfer function via Mason‟s rule
6. To analyze the stability of a system from the
transfer function
7. To sketch root locus and extract information
from it.
K. Course Outcomes
Course outcomes or learning outcomes reflect
the degree to which the program has met its
objectives; outcome indicators, the assessment
instruments and procedures that will be used to
determine whether the graduates have achieved the
outcomes. After successful completion of the
„Control Systems‟ course with a minimum grade of
„C+‟, the students will be able to
1. Know the benefits of using control systems
2. Design and analysis of various control systems
3. Find out the transfer function of electrical
circuits, mechanical and electromechanical
systems
4. Describe quantitatively the transient response
of first and second order systems
5. Find the overall transfer function from the
block diagram and signal flow graph
6. Understand and determine the stability using
the Routh-Hurwitz technique
7. Use root-locus design to meet stability and to
find the transient response
8. Find the digital responses from the transfer
function
9. Draw the block diagram from the dynamic
equation and represent the time domain system
in state-space form.
IV. BLOOM’S TAXONOMY
The idea for this classification system was
formed at an informal meeting of college
examiners attending the 1948 American
Psychological Association Convention in Boston.
At this meeting, interest was expressed in a
theoretical framework which could be used to
facilitate communication among examiners. This
group felt that such a framework could do much to
promote the exchange of test materials and ideas
about testing. In addition, it could be helpful in
stimulating research on examining and on the
relations between examining and education. After
considerable discussion, there was agreement that
such a theoretical framework might best be
obtained through a system of classifying the goals
of the educational process, since educational
objectives provide the basis for building curricula
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International Conference on Tertiary Education (ICTERC 2013) Daffodil International University, Dhaka, Bangladesh 19-21 January 2013.
and tests and represent the starting point for much
of our educational research [20].
Bloom's Taxonomy is a classification of learning
objectives within education proposed in 1956 by a
committee of educators chaired by Benjamin
Bloom. Although named after Bloom, the
publication followed a series of conferences from
1949 to 1953, which were designed to improve
communication between educators on the design of
curricula and examinations [21].
It refers to a classification of the different
objectives that educators set for the students, i.e.
the learning objectives. Bloom's Taxonomy divides
educational objectives into three domains:
Cognitive, Affective and Psychomotor (sometimes
loosely described as knowing/head, feeling/heart
and doing/hands respectively). Within the domains,
learning at the higher levels is dependent on having
attained prerequisite knowledge and skills at lower
levels [22]. A goal of Bloom's Taxonomy is to
motivate educators to focus on all three domains,
creating a more holistic form of education. A
revised version of the taxonomy was created in
2000 [23-25].
V. COURSE OUTCOME ACHIEVEMENT IN
COGNITIVE DOMAIN
To determine the achievement of the course
outcomes in the cognitive domain it is first
necessary to analyze the educational objectives and
corresponding learning abilities of the students at
different levels of the cognitive domain. These are
given in Table I. To illustrate that these educational
objectives have been achieved in the „Control
Systems‟ course, the turning control system design
problem for a tracked vehicle has been selected
[26]. This design problem involves the selection of
two parameters of the system: one is system gain
(K) and the other is the zero of the system (a). The
whole system is shown in Fig. 2 (a) and its model
is shown in Fig. 2 (b). The two tracks are operated
at different speeds in order to turn the vehicle. The
objective here is to select the values of K and a so
that the system is stable and the steady-state error
for a ramp command input is less than or equal to
24% of the magnitude of the command input signal
[1].
The characteristics equation of the system is shown in
equation (1).
(1)
1  Gc  s  G  s   0
Bloom also considered the initial effort to be a
starting point, as evidenced in a memorandum from
1971 in which he said, “Ideally each major field
should have its own taxonomy in its own language
- more detailed, closer to the special language and
thinking of its experts, reflecting its own
appropriate sub-divisions and levels of education,
with possible new categories, combinations of
categories and omitting categories as appropriate”
[23].
Skills in the cognitive domain revolve around
knowledge, comprehension, and critical thinking of
a particular topic. Traditional education tends to
emphasize the skills in this domain, particularly the
lower-order objectives. There are six levels in the
taxonomy, moving through the lowest order
processes to the highest. Through these six
processes a student gain knowledge and skills and
be able to solve real life problems of their fields of
interest. Therefore, to teach the „Control Systems‟
course for the undergraduate electrical and
electronic engineering students, cognitive domain
has been selected for teaching and learning process.
From the model in Fig. 2 (b), we can write equation (2).
K  s  a
(2)
1
0
s  s  1 s  2  s  5
Finally, we can rearrange and write equation (3).
s 4  8s3  17s 2   K  10  s  Ka  0
(3)
TABLE I
ACHIEVEMENT OF BLOOM’S TAXONOMY OF EDUCATIONAL
OBJECTIVES IN COGNITIVE DOMAIN [16]
Cognitive
Level
1
Educational
Objectives
Knowledge
List, cite
2
3
Comprehension
Application
Explain, paraphrase
Calculate, solve, determine
4
Analysis
Classify, predict, model,
derive, interpret
5
Synthesis
6
Evaluation
Learning Ability
Propose, create, invent,
design, improve
Judge, select, critique,
justify, optimize
To determine the stable region of K and a,
Routh-Hurwitz stability criteria is used and from
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International Conference on Tertiary Education (ICTERC 2013) Daffodil International University, Dhaka, Bangladesh 19-21 January 2013.
the Routhian array the range of K for which the
system is stable is found. Then for the ramp input
signal, r  t   At , t  0, the steady-state error (ess)
was found. Finally, the relationship among ess, K
and a are determined and the stable region is found
out by plotting the graph of a versus K. The
maximum value of K and a have also been
extracted from the graph [1].
Throttle
Steering
Track
Torque
Right
Power Train
and Controller
Left
Vehicle
Y(s)
Direction
of travel
Question: What is the purpose of finding the
value of K?
M. Comprehension
At this level, students demonstrate understanding
of terms and concepts and explain the concept in
their own words and also interpret the results.
Here, students demonstrate the understanding of
the facts and ideas by organizing, comparing,
translating, interpreting, giving descriptions and
stating main ideas and also by extrapolation.
Question: Can the students understand which
method required to be used to find the value of K?
Difference in track speed
N. Application
(a)
R(s) +
Desired direction
of turning
Controller
Gc(s)
Power Train and
Vehicle, G(s)
s  a
s  1
K
s  s  2  s  5 
Y(s)
(b)
Fig. 2 (a) Turning control system for a twotrack vehicle;
(b) Block diagram with the transfer functions.
How the educational objectives are achieved for
this particular problem of control system design at
six different cognitive levels is assessed in the
following sub-sections to demonstrate the student‟s
learning processes and skills upon the course
contents.
L. Knowledge
At this level, students are provided with
sufficient knowledge so that they can list or state
the problems and also exhibit memory of
previously learned materials by recalling facts,
terms, basic concepts and answers. Knowledge
may be of different categories, such as,
Knowledge of specifics- terminology, specific
facts
Knowledge of ways and means of dealing with
specifics- conventions, trends and sequences,
classifications
and
categories,
criteria,
methodology
Knowledge of the universals and abstractions in
a field- principles and generalizations, theories and
structures
At this level, students apply the learned
information to solve a problem, to calculate or to
solve for the required value. The students also
solve problems to new situations by applying
acquired knowledge, facts, techniques and rules in
a different way.
Question: What are the signs of the elements of
the first column after the computation of the
Routhian array?
O. Analysis
At this level, students break things down into
their elements, formulate theoretical explanations
or mathematical or logical models for observed
phenomena, derive or explain something by
identifying motives or causes. They make
inferences and find evidence to support
generalizations. They also do analysis of elements,
analysis of relationships or analysis of
organizational principles.
Question: How many poles are the in the right
half or left half of the s-plane using the RouthHurwitz stability criterion?
P. Synthesis
At this level, students create something
combining elements in novel ways; formulate an
alternative to the existing design. They also
compile information together in a new pattern to
produce a unique communication or to propose a
set of operations or to derive a set of abstract
relations.
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International Conference on Tertiary Education (ICTERC 2013) Daffodil International University, Dhaka, Bangladesh 19-21 January 2013.
[4]
Question: Can the students find the value of
steady-state error, ess from the value of K?
[5]
Q. Evaluation
At this level, students make and justify the
values obtained by judgment or select an
appropriate value among the various alternatives
and also determine which one is better and explain
its reasoning, analyze the values critically for
accuracy and precision. They also opine by making
judgments about information, validity of ideas or
quality of work based on a set of criteria or
evidences.
Question: Can the students find the region of
stability for a given value of ess?
VI. CONCLUSIONS
The engineering graduates must be well prepared
in the changing global competitive knowledgebased industry. Like all of us in the world, the
engineering graduates must have the ability for
knowledge management. Therefore, universities
are facing challenges as well as opportunities for
creating and transferring knowledge to the students
in efficient and smart way for their survival.
This paper describes the teaching and learning
method of „Control Systems‟ course for electrical
and electronic engineering students in cognitive
domain, a critical learning domain that includes the
recall of knowledge and cultivation of intellectual
skills. Certain cognitive processes, such as,
problem solving, critical thinking, reasoning,
analysis and evaluations are very important in
engineering tasks. Since „Control Systems‟ is an
important core course in the curriculum of
undergraduate electrical and electronic engineering
program, therefore, this course must be taught in
such a way so that the students are able to develop
their knowledge and skills on designing and
analysis of various types of control systems in their
real life works.
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