Remote Educational Experiment Applied To the Discipline of

Remote Educational Experiment Applied
To the Discipline of Control Systems
J. M. Neto1-2, C.S.Silva1, A. D. Spacek1-2, O H. A. Junior1-2
1
2
School of Engineering, Department of Electrical Engineering SATC, Criciúma-Sc (Brazil)
School of Engineering UFRGS, Federal University of Rio Grande do Sul Porto Alegre-Rs (Brazil)
Abstract— Engineering education has become a relevant
aspect for most countries since it has been recognized that
skilled engineers are important for optimization of
production processes to ensure high productivity and quality.
Considering education on control systems, a key issue for
more efficiency processes, this paper presents the
development of an educational experiment concerning remote
control applied to a pneumatic levitation system. The
proposed architecture is based on the use of an Arduino Uno
and Ethernet shield, whose function is to interface between
the experiment and the Internet. The user can access the
control experiment through an application developed in Java,
which allows the students to choose the model of the
controller (P, PI and PID) they want to study, change its
parameters simultaneously and view system response
through graphics and webcam. The results obtained with the
experiment proved promising the potential application of that
type of architecture. In this context, the use of
experimentation remote collaborated for learning of students
on the specific area of control systems.
Keywords: Arduino; Remote Experiment; Engineering
Education.
I.
INTRODUTION
The consolidated use of the Internet as a tool for
sharing information, along with the development of
modern mechanisms of control, acquisition and
distribution of data through computer networks, are
stimulating the emergence of virtual learning
environments.
Observing this panorama, universities look for
different ways to enthuse and motivate their students who
have difficulties adapting to the traditional teaching
techniques applied in the classroom. Such difficulty is
justified by the high volume of information and the way
people use the content to which they are exposed. In search
of solutions, there are several studies involving new
teaching methods, referred to as desirable methods, which
are alternatives that help and facilitate the understanding of
the subjects taught in the classroom for this new
generation of "plugged-in people". [5]
Nowadays, engineers, technologists and researchers
whose needs, applications, and requirements quickly
change, need the flexibility to create their own solutions.
This is a reality in the labour market and strengthens on the
academic environment, where students need the freedom
to experiment without fear of damaging equipments and
components. However, real experiments installed in
laboratories of educational institutions are usually
expensive, that is, besides the cost of the equipment the
institution needs to pay for the maintenance, installation
and possible replacement of materials used in the real
experiment. Associated with these economic factors there
is the increasing number of students, which reflects on the
increasing number of laboratories at universities and other
educational institutions. [12]
The remote experimentation emerges as an extremely
interesting alternative to limited availability of university
laboratories in Brazil for disciplines involving electronics
and control system. One observes the necessity of using
simulators and prototypes to demonstrate the operation and
application of the concepts obtained in the classroom,
which will help the student understand the concepts taught.
Laboratories are used to help fixing the theoretical
principles demonstrated in practice [1]. When used
properly, they can enthuse, motivate and inspire students,
since it can be accessed at any time and will be connected
to the global network of computers, available 24 hours a
day, 7 days a week. With this availability of access, it
becomes easy for the user to interact with the remote
practical activity. The existing laboratory models generally
consist of a set of hardware and software technologies,
which can take several different configurations, depending
on the chosen technological means used in its
implementation. [5] [14] [13]
Thus, the purpose of this study is to implement a
remote educational experiment focused on supporting
practical activities in the discipline of control systems
present in the course curriculum of Electrical Engineering,
Technology and Industrial Automation. This way, the
student will be able to control the levitation of a Styrofoam
ball through a tube driven by an air pump. The student will
have dynamically access in real time to a graphical
interface system response, along with the video image via
webcam connected online to the prototype, addressing
topics related to the discipline. Thus, the student will be
able to access the parameters of the digital PID controller
through a visual interface via web. Through the website, he
will be able to schedule the time to use the experiment and
answer the questions elaborated by the teacher.
ICBL2013 – International Conference on Interactive Computer aided Blended Learning
Page 369
II. EXPERIMENT ARCHITECTURE
Figure 1 shows the basic diagram architecture of the
remote experiment, where the main characteristics
regarding the structure proposed are detailed below. [2]
function of identifying Arduino UNO in the network by its
MAC (Media Access Control), a physical address
associated with the communication interface that connects
a device to the internet network. When the user uses the
visual interface, this will search for the programmed MAC
in the network that establishes the connection to the
experiment. [4] [11] [10]
Figure 2. Basic Operation Diagram of Data Traffic.
Figure 1. Architecture of the Remote Experiment.
A. Hardware Implementation
This block consists of an Arduino Uno, composed of
an electronic board based on the ATMEGA328 chip,
produced by Atmel, which has 14 input or output digital
pins, from which 6 can be used as PWM outputs, 6 analog
inputs, includes a crystal oscillator 16 MHz, USB
controller, a supply connection and a connector ICSP. [7]
[9]. However, to connect to the internet network is
required to use the Ethernet shield, with the main purpose
of receiving and sending information through the IEEE
802.3 protocol. Among the different options of controllers
with Ethernet communication functions, the model used in
this study was the Microchip ENC28J60. Refer to TABLE
for further details. [10] [4]
When the user access the interface to perform the
experiment, he will have levitation control of the
Styrofoam ball through the electric air pump motor via
data transmission network (see Fig 2). The Arduino UNO
will control by pulse-width modulation, termed PWM and
to measure the height of the Styrofoam ball the component
used is the HC-SR04 Ultrasonic Sensor. In Figure 3 the
system is shown.
TABLE 1.
TECHNICAL CHARACTERISTICS OF ENC28J60. [4][10]
MAC
PHY
TX/RX RAM Buffer (Bytes)
Interrupt pin
LED
Operating Voltage (V)
Minimum Temperature (°C)
Maximum Temperature (°C)
Communication
Pre-programmed MAC address
Security Mechanisms
Ethernet Controller
Yes
Yes
8192
1
2
3.3
-40
85
SPI
No
No
10Base-T
Figure 2 shows in detail the structure of the data
transmission system proposed. The Ethernet schield board
is represented by chip ENC28J60 from Microchip, as it is
the main component of the board. The Arduino UNO
communicates with the chip through the SPI bus, as the
name itself indicates, is a standard serial communication
interface among device controllers and synchronous
peripheral widely used nowadays. The chip has the
Figure 3. Connection Scheme of the Proposed System
ICBL2013 – International Conference on Interactive Computer aided Blended Learning
Page 370
B. Prototype Assembly
The levitator tube of the Styrofoam ball was built
based on the Bernoulli principle, which ensures that for a
flow with no viscosity the increase in fluid speed occurs
simultaneously with a decrease in pressure or a reduction
in the potential energy of the fluid. This effect is known as
the Bernoulli principle created by Daniel Bernoulli, Swiss
scientist of the eighteenth century, who identified the
relationship between speed and pressure. The Bernoulli
principle can be demonstrated using a Venturi tube, see
Figure 4. Through this perspective, the experiment may be
used in the lower levels of bachelor's degree programs.
[15]
After confirming the functionality of the tube, was
initiated the assembly stage, by using a PVC pipe with
50mm diameter and 700 mm in length. After making the
cut-outs, the box displayed in Figure 6 (b) was used for
fixation of the tube and accommodation of Figure 6
components (c) (g) (b), creating an equipment protected
from accidental interventions and aesthetically appropriate
to different environments. Concluding the initial assembly
was confectioned a tube that meets the methodology of
Bernoulli and Venturi, making it visible to the user of the
equipment Figure 6 (f), so that it would be sufficiently
transparent making visible the ball to the user (see Figure 6
(d) (e)). Satisfactory results were obtained with the
conclusion of the assembly, see Figure 6 (c).
Figure 4. Venturi Tube Model.
The concept was applied to this work in a
differentiated way, that rather than narrowing in the centre,
it occurs around the perimeter of the ball, where remains in
an airstream, due to low pressure created around its
surface. See Figure 5. While the air passes through the
tube and reaches the part identified in Figure 5 with block
(A), the air flow speeds and places the ball in the centre of
the tube. The high speed airflow that flows by the sides
causes the side-thrust effect, a kind of perpendicular force
towards the ball. Refer to Figure 5 and Table.
Figure 6. Prototype Assembly.
C. Software Implementation
Figure 5. Venturi Tube Model Applied to This Study.
TABLE 2.
BLOCK DESCRIPTION REFERRING TO THE FIGURE ABOVE.
Block
A
B
Purpose
Surrounding air with high pressure exerts a
restoring force on the ball, leaving it in
balance, floating point.
Air speeds up around the Styrofoam ball and
creates a pocket of low-pressure air.
The software implementation was partially developed.
During the prototype functionality testing phase was
created the PID control algorithm, then was initiated the
implementation of the communication among the
experiment and the internet, divided in Arduino UNO and
PHP programming language.
For the development of PID algorithm was used the
library named PID_V1, available at the Arduino website
[9], however some adaptations were carried out to its
operation in this study. The PID library will perform the
calculations using proportional, integral and derivative
parameters, determined by the user based on the height of
the ball, defining an output value, sending to the main
program a variable called Output. To conduct data
ICBL2013 – International Conference on Interactive Computer aided Blended Learning
Page 371
collection the library was added to the main program
(Ultrasonic) Figure 7, responsible for calculating the
height of the Styrofoam ball, through the data received by
the HC-SR04 Ultrasonic Sensor (see Figure 3), used to
identify the system response. Pin 7 of Arduino UNO was
named (pwm1), predefined as a PWM output that will
control the motor speed. When starting the program,
initially it will check the height of the ball and the control
parameters, being sent the data to the PID library, it
performs the calculations and decrease or increase the
motor speed through the 8 bits output (Output), which may
vary from 0 to 255. [7] [9]
The Arduino communication with the Internet is
carried with the help of a computer that has the server role
of the page developed in PHP, a sort of database. This
page in PHP has the function of sending and receiving data
from the server connected to the internet, and in turn
connected to the Internet shield adapter along with
Arduino UNO integrated to the experiment. The use of
PHP is due to not having total processing application on
the user's computer, facilitating the speed of data
processing. Since its operation is based on the network
connection, all data from the virtual environment are
located on a global computer server, and can therefore, be
accessed from anywhere. Then, as seen previously in the
algorithm to communicate Arduino UNO to the Internet
(Figure 8), this has two lines of experiment identification
called Byte IP and port that serve as identification of this
experiment to the network. After developing the PHP
algorithm (Figure 9), is observed the presence of a line
called socket_connect ($ sock,'' Byte'' IP, port), that is,
PHP connects to the IP and port (Figure 9), which shall be
equal to the algorithm of Arduino UNO, according to
Figure 8. [3] [8] [6]
Figure 7 - PID Control Algorithm.
With the conclusion of PID algorithm was started the
development of Arduino UNO communication algorithm,
with the Ethernet shield adapter for sending and receiving
the data into PHP. At first, Arduino UNO connects to any
network through its IP address (byte ip) and port (int port),
as can be seen in Figure 8. Connected to the network, the
program starts the IC ENC28J60 through the subroutine
(server_int ()), chip located in the Internet Shield adapter,
responsible for converting data of SPI bus, from Arduino
UNO to TCP-IP protocol, used in the network [10]. Then,
the program enters the subroutine (loop), when any data is
delivered by the network it will be stored in the input
BUFFER and converted to a variable, this will be checked
by the function (switch), if any, it will be assigned the
programmed function, failing that, nothing will happen.
Referring to the data sent from Arduino UNO to the
network, each data is assigned to a variable and stored in
the output BUFFER, by the end of the subroutine cycle the
data will be sent by the command (client_send_receive).
[9] [10] [7]
Figure 8 - Algoritmo para enviar e receber dados PHP.
Figure 9 – PHP Communication Algorithm.
D. Interaction With the Experiment Environment
The languages used in the development of the whole
visual environment were PHP for communication among
the website and the experiment, HTML for static and
structural effects, and finally Java Script along with AJAX
for dynamic data such as graphics and control displays.
The proposal is that the user interacts with the experiment
anywhere connected to the internet, where will have full
control of the experiment, such as changing PID
parameters in real time without having to disconnect the
equipment. Thus, will be able to visualize the system
behaviour with more detail with every change made. Will
be able to connect and disconnect the experiment
whenever one wants, check the graphical system response
and real time image through the camera of the experiment
to have more reliability and enthusiasm on what is being
ICBL2013 – International Conference on Interactive Computer aided Blended Learning
Page 372
done. The experiment interaction environment was placed
on a webpage, see Figure 10.
and similar to the laboratories of educational
environments, which can provide a better learning for
students of Electrical Engineering. The subject covered has
various conceptual contents taught in the classroom
throughout the course that can be better fixed with
practical activities in real laboratories.
To organize access to the experiment was developed of
a scheduling system, integrated with Moodle environment,
it was possible to restrict the access to the experiment. In
order to access the levitation system page, the user must
login into Moodle and schedule the desired time to access
the experiment. On the scheduling page, as in Figure 11,
it is possible to see all the reserved times, each scheduled
time reserves 30 minutes for that particular user, however
each user can register as many times as desired. It is also
possible to see a list of the reserved times and users.
Only the user with the scheduled time has access
levitation system. At the scheduled time, the user just
login into Moodle and access the experiment´s link. If the
user tries to make a direct access to the experiment’s link,
he will be redirected to Moodle’s login page. It is also
possible to see the other experiments available in the
laboratory, and if the user desires, the access to any free
experiments can also be scheduled.
Figure 10. Environment interaction with remote experiment.
The web page above shows where the levitation
system can be visualized in order to verify ball in
levitation. Beside it, there is the PHP that permits the user
to visualize ball in levitation in the graphic and control the
parameters of PID controller. This application has several
mechanisms to interact with the user; the functions of each
item are depicted in Figure 10. Table 3 shows in detail the
purpose of each block in the interaction environment
developed for the application.
TABLE 3
DESCRIPTION OF THE BLOCKS IN THE EXPERIMENT
ENVIRONMENT
Block
Name
1
Levitation
Graphic
2
Switch on or off
Turn on or turn off the pneumatic
levitation
3
Selection of the
experiment
parameters
Select the values of the setpoint and PID
controller parameters (kp, ki and kd)
4
Show the
application
Purpose
Visualize the values of ball levitation and
the setpoint over time.
Visualize the
experiment
levitating
ball
Figure 11: Booking System.
Analyzing the records of students’ accesses to some
experimental data (see Fig. 12), it is visible that while
some students prefer to access the remote experiment at
night, others prefer to work on it in the early afternoon.
Each student can choose the best time to conduct their
practice on the experiment.
and
III. ANALYSIS OF RESULTS
The main idea of this study is to conduct a remote
experiment mainly applied to the area of control system
Figure 12: Record of students’ accesses to the remote experiment.
ICBL2013 – International Conference on Interactive Computer aided Blended Learning
Page 373
The obtained results were very positive, it can be
observe by report of access indicates that most students
accepted the environment and contributes to fix the idea
of using remote laboratories with mixed environments is
more used as a learning strategy in teaching of school.
Using the remote environment, 40 students from the
discipline of Control Systems (Graduate Course in
Industrial Technology and Electrical Engineering)
participated in a blended learning scenario. From a
questionnaire responded by the students, it is possible to
note that most of the students accepted the environment
and collaborate to the idea of utilization of remote labs as
a learning strategy. Table 4 shows some of the questions
answered by the students. One of the most important
characteristics of the proposed environment highlighted by
the students is the flexibility of time to use the experiment.
TABLE 4.
QUIZ QUESTIONS AND ANSWERS.
Did the experiment contribute to better understand the concepts
developed in the discipline of control systems?
Excellent
Good
Regular
Bad
39%
31%
17%
13%
What is your impression about developing remote experiments to
control systems?
Excellent
Good
Regular
Bad
42%
37%
13%
8%
In your opinion, is there greater learning of control systems in the
development of activities linked to remote experiments or
simulations?
Real
Combination
Simulation
Both
experiments
of both
5%
31%
43%
21%
VI. CONCLUSION
From a pedagogic perspective of the recovering success
of the programmatic contents, this evaluation is a
promising technique of recovering since the environment
allows the student to perform the activities proposed and
explore other related control systems. It is also promising
in relation to the pedagogic relationship among different
learning experiences and in relation to the significance of
various “learning elements” integrated in the user’s
graphical interface.
The PID controller used in the experiment under study
resulted in adequate control of levitation system, the
earnings used as the response of the system satisfies the
expected. The simulation made from the transfer functions
obtained by graphical analysis of the convergence was
observed responses of the physical system implemented
with the theoretical control systems.
REFERENCES
[3] W. SOARES, Crie um framework para sistemas web com
php 5 e ajax, São paulo: Editora Érica Ltda, 2009.
[4] MICROCHIP, “Microchip ENC28J60 Data Sheet,” 2008.
[Online]. [Acesso em 2013 05 20].
[5] R. MARCELINO, “Ambiente virtual de aprendizagem
integrado a mundo virtual 3D e a experimento remoto
aplicados ao tema resistencia dos materiais,” Porto Alegre,
2010.
[6] J. A. n. MANZANO, Guia de orientação e desenvolvimento
de sites, São paulo: Erica, 2010.
[7] E. GUIMARÃES, Apostila Arduino, Niteroi: Universidade
Federal Fluminense, 2010.
[8] T. P. Group, “The PHP Group,” 2005. [Online]. Available:
<http://www.php.net/manual/pt_BR/history.php>. [Acesso
em 09 05 2013].
[9] Arduino,
“Arduino,”
2011.
[Online].
Available:
http://arduino.cc/en/Main/ArduinoBoardUno. [Acesso em
10 01 2012].
[10] “Arduino Ethernet Shield,” [Online]. Available:
http://arduino.cc/en/Guide/ArduinoEthernetShield. [Acesso
em 02 01 2012].
[11] R. SANTOS, “Sistemas de Comunicação Digital (T5) SPI,” Universidade Federal do Rio de Janeiro (UFRJ), Rio
de Janeiro, 2010.
[12] M. T. CHELLA, “Arquitetura para Laboratorio de Acesso
Remoto com Aplicações Educacionais .125f.,” Tese
Departamento de Engenharia Eletrica e da ComputaçãoFeec, Universidade Estadual de Campinas - Inicamp,
Campinas, 2006.
[13] J. Neto, R. MARCELINO, C. e. PEREIRA, V. GRUPEE, J.
SILVA e S. PALADINI, “Remote Educational Experiment
Applied To Eletrical Engineering,” Internatonal Jornal Of
online Engineering(IJOE) V.9,pag47-51, Criciuma, 2013.
[14] F. M. Schaf e C. E. a. H. R. B. V. Perreira, “Blended
Learning using GCAR-EAD Environment: Experiences and
Application Results. In,” 17th IFAC World Congress, 2008,
Seoul. Proceedings of the 17th IFAC World Congress,. p.
12637-12642., 2008.
[15] R. C. d. C. VIEIRA e P. P. SILVA, Atlas de mecânica dos
fluidos : cinemática, São Paulo: Edgard Blucher 130p.,
1971.
AUTHORS
J. M. Neto teacher of Department of Electrical
Engineering SATC, Street Pascoal Meller, 73.
Criciúma-SC (Brazil) ([email protected]).
C. S. Silva student of Electrical Engineering in
SATC, Street Pascoal Meller, 73. Criciúma-SC (Brazil)
([email protected]).
A. D. Spacek teacher of Department of Electrical
Engineering SATC, Street Pascoal Meller, 73.
Criciúma-SC (Brazil) ([email protected]).
O. H. A. Junior teacher of Department of Electrical
Engineering SATC, Street Pascoal Meller, 73.
Criciúma-SC (Brazil) ([email protected]).
[1] D. O. C. TOMÉ, “Acesso a Laboratórios Remotos via
Ambientes Imersivos,” Porto, 2010.
[2] A. S. TANENBAUM, Redes de computadores, Rio de
janeiro: Campus, 2003.
ICBL2013 – International Conference on Interactive Computer aided Blended Learning
Page 374