Virtual laboratories on the net
Andrea Bagnasco,
Marco Chirico, Giancarlo Parodi, Andrea Sappia and Anna Marina
Scapolla
Department of Biophysical and Electronic Engineering
University of Genoa
Via All’Opera Pia 11/A - 16145 Genoa, Italy
Telephone: +39-10-3532192
Fax: +39-10-3532175
E-mail: chirico@dibe.unige.it
Abstract
New educational and training environments based on the network can give a response to the increasing demand of new models of learning. In this paper, a system for practice on electronic measurement methodologies based on the virtual access to real and simulated laboratories is presented. The same software model can be also applied to industrial equipment for the remote monitoring end control of the devices and the remote training of personnel.
1. Introduction
The exponential development and diffusion of information
technologies of the last few years have produced a great acceleration
toward the "information society". New models of work
organisation such as virtual enterprises and telework, induce
demands for relevant changes of the educational systems in order
to take into account the needs of the learner [1].
We assist to a trend toward a larger autonomy of the trainee that
chooses personalised training curricula and toward the progressive
overcoming of the limitations of times and places that
characterise conventional educational systems. This process leads
to a new educational paradigm, based on virtual classes, with a
high level of interactivity. The virtual approach is suitable for
continuos education, home learning, professional training, that
broadens to encompass the citizen (not only the specialist) in
his whole life [2].
In this scenario multimedia technologies play a special role.
They allow the use of new pedagogical materials, such as audio/video
recordings, hypertexts, educational software (courseware),
supported by new distance delivery tools, such as the Web [3].
The diffusion of the World Wide Web has generated a large
interest in its educational use and originated several
experiments of learning activities based on Internet. Preliminary
results have shown the considerable effectiveness and versatility
of the network as a delivery medium, and the design of supporting
learning systems, co-operative work and virtual environments has
become extremely relevant [4].
It is worth noting that practice is an important component in
most of the technical disciplines and delivering remote access to laboratories
is a way of introducing trainees into real experiences. Our
approach helps to overcome the lack of personnel and resources,
typical of educational institutions, and allows sharing complex
and expensive instrumentation, that normally cannot be devoted to
education.
In this paper we present the model of a virtual laboratory, accessible in Internet, and its application to different subjects: the analog and digital electronics education and the remote control of industrial processes.
2. The environment architecture
The hardware/software environment consists of three main components: the virtual laboratory (VL), the distribution layer (DL) and the client (CL). The VL can be available to the clients according to different methodologies of distribution that are illustrated in detail.
2.1 The Virtual Laboratory
The Virtual Laboratory can be seen as a generic device under electronic control or testing. Examples of VL’s can be a single electronic instrument, a collection of electronic instruments or an integrated electronic measurement bench. In the field of factory automation, the same techniques can be applied to PC controlled environments and monitoring systems.
In this context the term "virtual" refers to
the representation of the laboratory, that is distributed on the
network and allows the interaction with the devices. The virtual
access approach is effective towards both real instrumentation
laboratories and totally simulated ones. The real laboratory can
consist of one instrument or of a collection of instruments
managed by a server via IEEE488 interfaces. The simulated
laboratory is instead a collection of software libraries that
emulate the behaviour of the real instruments, reacting to the
operator commands and generating correct data depending on the
experiment.
The VL is based on the same software interfaces both in the real
and simulated case, in a completely transparent way for the user.
The Virtual Instrument (VI) is the building block of the VL.
In Figure 1, the virtual instrument components are shown. The main
scope of the virtual instrument is to drive a real instrument or
its simulated implementation.
The virtual instrument consists of three main components:
Both in the real and in the simulated case, the interaction between the user and the instrument is implemented through the user interface that generates a unique stream of data to be sent to the drivers. The components of the VI can be distributed on different platforms, exchanging information on the network. The user interface allows the remote access to the laboratory by web browsers. The network distributed VI is shown in Figure 2.
2.2 The Distribution Layer
We have studied different implementations for the distribution layer. An implementation is based on a web server that distributes HTML documents describing the VL scope and managing the interaction between the user and the VL by means of Common Gateway Interface (CGI) programs. In this way, the user reads on his browser the actual status of the control panels of the instrumentation and sends command strings to the instruments compiling forms and selecting sensitive maps on the HTML page. The CGI programs implement the interaction with the instruments translating this information into commands and retrieving the results of the operations. The results are then translated into HTML pages and sent back to the clients. In Figure 3, this solution is shown.
In Figure 4, another implementation scheme is presented. The web server contains HTML documents that describe the VL functionality. The web server distributes a program, named vlab interface, to be executed on the client platform . The vlab interface contains the VI user interfaces and interacts directly with the VL via TCP/IP. In the previous approach all the communications were based on the HTTP protocol an managed by the web server, in this case a direct communication channel is set up and the web server only introduces to the VL. Following this approach, it is also possible to release a standalone version of the VL to be delivered on magnetic media.
It is worth noting that, the client basic tool for the access to the VL is a standard browser in all the possible DL configurations. In the second implementation the browser must only be customised to be able to open VL files.
3. Applications
The VL model has been applied to different fields of application, such as the education on electronics during engineering graduation curricula and the remote industrial monitoring and control. For what concern these prototypes, the VL components have been developed using the Labview software from National Instruments [5].
3.1 An electronic instrumentation laboratory for education
The purpose of this application is to integrate the training
with practical experimentation, in order to acquire knowledge
about measurement methodologies on electronic circuits and, at
the same time, gain the capability to operate laboratory instrumentation.
The students are introduced to the VL by hypertexts that describe
the environment and guide them through the execution of the
experiments that can be both totally simulated and carried on
real instrumentation.
The VL consists of a set of electronic instruments (oscilloscope,
multimeter, and function generator) and a set of circuits under
test (resistor networks, low-bandwidth filters).
In the real case, the instruments are connected to a PC server
via IEEE488 bus. In the simulated case, the laboratory is based
on two software libraries: the instrument library and the circuit
library. The students download the same user interface both in
the real and in the simulated case. In Figure 5 an exercise
involving an oscilloscope, a function generator and a circuit under
test is shown.
3.2 A supervisory system for a photo-voltaic station
The VL model has been applied to an existing industrial system
to remotely access and supervise it.
The application addresses the monitoring of the equipment and
allows to analyse and display the status of the devices. It also lets
the operator to query the data log files and trasmit them via
E-mail, to be notified of the alarm states via E-mail. Moreover,
it is possible to manage the access rights to the system for
different levels of users (administrator, operator, standard
user).
In Figure 6 the display of real time collected
data is shown.
It is worth noting that the same environment could also be used
to train personnel to operate on complex, dangerous or distant
equipments, replying to the increasing demand of continuous
education.
4. Conclusions and future work
A virtual approach to access laboratories via network is presented. The main benefits are the flexibility of the model that can address in a transparent way both real and simulated instrumentation and the reduced cost of the clients needed to access the environment. Possible utilisations are in the field of distance education and training and for the remote control of industrial processes. Future work will concern the development of further applications based on this technique to study possible extensions of the model. Didactic experiments will be carried on during the courses of electronics to verify the effectiveness of the environment and its pedagogical results.
Acknowledgements
This research has been carried out in co-operation with Ing. Andrea Cambiaso of Quanta Srl.
Reference