A network-based electrical engineering laboratory.

Technical education is, by definition, a field that requires hands-on practice and experience by the student. When it comes to distant learning, technical education suffers from lack of such practical study, given the fact that e-learning is based on theoretical material being provided remotely to the student. This article presents the idea of assisting technical education that is provided remotely, by introducing a remotely controlled laboratory--a key feature in technical education fields such as electrical engineering. Furthermore, the paper discusses functionality and practical application of such an idea, using an implemented example of a remotely controlled robotic arm and an online education platform while the observed results are evaluated, accompanied by the conclusions that the scientific team reached.

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It is a recognized fact that technical education's main differentiation to theoretical education is the practical aspects involved, such as laboratory equipment and electronic appliances, which actually facilitate comprehension and further intellectual possession of the studied subject. Students learn to operate laboratory devices so as to exploit them as tools for their education. Of course, the theoretical approach of a studied subject lies in direct association with its practical application. Students are taught, for example, the different ways to calculate a theoretical result of an experiment and then are requested to verify the result by conducting the experiment themselves using laboratory equipment.

The idea--and necessity--of being able to use laboratory equipment not only on campus but also remotely, is evident. When it comes down to complicated experiments and measurements, sophisticated equipment is required. Due to high expenses and low budgetary portions invested on such devices, institutions often lack the ability to offer cutting-edge educational equipment, thus granting underprivileged education to their students compared to such offered by wealthy institutions. The need for some indirect way to deliver equally sufficient education to underprivileged students is obvious. Therefore, remote access to other institutional laboratories enables students to perform experiments and calculations, using equipment, which is not available at their home institution. The cost effectiveness of such remotely controlled equipment also minimizes the need for extra room to host newly formed laboratories and equipment, which is a common problem, often met in many institutions. Finally, the much discussed aspect of lifelong education is directly assisted by remotely accessible electronic equipment since the potential life-time researcher has the opportunity to use such equipment on demand without having to be physically present in the location of a particular institution.

In this article we present the framework for engineering courses based on combination of traditional e-learning environment and remotely accessible laboratory experiments that have been developed under a SOCRATES-MINERVA project partially financed by the European Union.

LITERATURE REVIEW

The E-Learning Environment

Traditional e-learning platforms offer internet access to educational material, and problems that enable self-assessment and final assessment of the students' performance. It is often a fact that students do not organize their studying time correctly or more accurately they choose not to classify and prioritize their tasks so that they make full use of their daily "spare" time. This is partly due to the tendency students have to be imprudent and react negatively to the suggested study framework in their institutions. Introducing e-learning capabilities to the students has a positive effect on their daily study schedule since students are permitted to organize their time at will and assemble a personal, satisfactory timetable for studying. A rather radical, though real-life-oriented, example would be that of students willing to do their homework after midnight. Such students have the capability, by use of an e-learning platform, to read through the relevant educative material, deliver their homework online, and probably even perform some sort of laboratory experiments connected with the class they are working on.

An example of distant learning courses is that of the National Technological University of the USA, which offers a variety of distant learning courses even compiled on CD-Rom or DVD formats. Though interesting the courses may be, they do not include hands-on methods that would allow students to apply the acquired knowledge on practical engineering problems and observe the results.

Remote Laboratories

However, in most engineering courses it is desirable if not necessary, that the students have hands-on experience with actual equipment in order to connect the theoretical component of their education with practical experiments and projects. There have been several efforts to make laboratory equipment available. Investigating existing e-learning platforms and remote laboratory installations, is an interesting task for the researcher so that similar cases are studied and available conclusions are taken into account for further consideration. Although some of the existing distant learning platforms do not include remote use of equipment, some examples were reviewed.

The REmoTe Worldwide Instrumentation NEtwork (RETWINE) project is an example of remotely operated laboratory equipment located in three European educational institutes. Students can perform measurements and receive real-time results on equipment, which has been connected to the network established for the project. The web interface is a replication of the real equipment with graphically designed knobs and switches. The users may input data manually by use of their keyboard and wait for the results on the graphical replication's screen as if looking at the actual screen of the equipment. The courses offered, though, are equipment-oriented, meaning that the actual course does not have a tutorial subject of its own but is based on the function and operation of the equipment.

The Bugscope is an educational project by the Imagine Technology Group of the University of Illinois. The idea behind the project is to remotely control an environmental scanning electron microscope so as to view the specimen under test through the Internet. Since, such a device is too expensive for schools of the first and second level of education (K-12 students) as well as small institutes, the opportunity grants the tutor a great tool to support the lesson. Tutors can apply for an online session for their classes through a web-based application and schedule their session in cooperation with the project's coordinators. The lack of an identifiable and complete coursework to establish the project on, renders the project a cost-effective tool to broaden lower education opportunities rather than an extension of distant learning education.

AN E-LEARNING PLATFORM ILLUSTRATED

Working within the context of the E.U. "eMerge" program, a remotely accessed laboratory was designed and implemented to show the characteristics of remote education. A website which servers as a secure portal offers access to the remote laboratory (Figure 1).

Students can practice their knowledge on a series of remotely operated laboratory experiments (projects) designed for the matter. Practical application of knowledge being one of the key-aspects of engineering education, the remote laboratory features easy-to-use, web-accessed, real-time experiments where students materialize knowledge provided by the studied coursework.

[FIGURE 1 OMITTED]

System Architecture

The e-learning portal and remote laboratory system described can be accessed through the Internet by any computer with internet access. This is due to the fact that the communication protocols used, between the server computer and the client (student's) computer, are not proprietary protocols developed for sole use with the system rather certified protocols such as the widely used "PPP," which are globally acknowledged and used. This serves the purpose of making the remote laboratory globally available.

As for the laboratory equipment itself, the system includes a series of experiments varying from measurements on electronic instruments such as capacitors and resistances as well as electronically controlled filling of water tanks to the later-to-be-described case of the remotely operated robotic arm. All experiments are preceded by coursework material for students to read and thorough guidance of each experiment's function.

CASE STUDY OF THE REMOTELY CONTROLLED ROBOTIC ARM SYSTEM

Robotic Arm System Description

The illustrated system is an example of one of these experiments composing the remote laboratory. The idea was to make use of an existing six-axis robotic arm (Figure 2) located at a laboratory of the institution and realize a hardware as well as software interface for its remote operation. The existing robotic arm consists of 6 axis, each one having a rotating capability of at least 240 degrees. This identifies the robot as one having six degrees-of-freedom, that is the manipulator can control up to six robotic movements. It is considered to be a rule of general acceptance that the more the degrees of freedom a robot has, the better the robot itself is considered, always depending on the purposes of its use.

From the mechanical/electrical point of view this means that the robot has six motors--in the case described all motors are DC motors powered through two cables connected on either side of each motor's coil. When the anode of the supply source is connected to one side of the coil and the cathode to the other the motor rotates to one direction, either left or right. If the anode and cathode of the supply source switch connections so that the cathode is connected where the anode was and vice versa then the motor will rotate to the other direction, in "reverse."

Each arm junction has, apart from the motor to rotate the attached arm part, a rotating resistor or "potentiometer" attached to the motor's axis so that it rotates the same way as the motor does. A voltage of approximately five volts is applied on the potentiometer so that by measuring the voltage between its remaining point and the ground, one can have a specific voltage measurement for each position of the potentiometer. This procedure identifies the position of each arm translated into the voltage measured at the remaining point.

[FIGURE 2 OMITTED]

The computer is equipped with an interface card provided by National Instruments, which has several analog and digital I/O lines to acquire and transmit signals/data. Due to technical malfunctions on behalf of the robotic arm, it was decided that only three of the six arm parts should be used to demonstrate control of the arm. Thus three digital output lines were used to control the motors of the arm parts and three analog input lines to measure the voltage of the potentiometers, enabling identification of the position of each arm part in accordance to its original position, defined by the voltage measurement.

The digital lines, by default, are capable of giving an output of two states, logical "1" and logical "0," which is interpreted in actual voltage as +5V and 0V (ground). Logical "1" is considered to be the "forward" direction of the rotation of each motor and logical "0" is considered "reverse" direction. As a final step, concerning the hardware infrastructure of the control unit, an original interface circuit board--namely, a controller--had to be developed to control the motors' rotation. A simplified version of an H-Bridge is used to control the rotation.

An H-Bridge is an arrangement of four transistors, paired off in complementary pairs (one NPN, one PNP). As the diagram shows (Figure 3), the first pair's bases are connected together to the digital line and the second pair's bases are connected to the digital line through an inverter. It is obvious that when, for example, the digital line is on logical "1," the NPN transistor of the first pair as well as the PNP transistor of the second pair go into conduction mode, thus supplying the motor with positive charge on the left and negative on the right which as a combination rotate the motor forward. In the case when the digital line goes to logical "0," the two remaining transistors go into conduction mode whereas the first two stop conducting current. This brings the positive charge to the right side of the motor and the negative on the left, which, consequently, drives the motor in reverse.

As for the program to control the hardware interface, its structure is rather simple. The main idea is that, when the system runs in idle mode--the user does not force the robot into some specific movement--the program gives a continuous alternation of logical "1"s and "0"s so that the motor stays at its current position, while at the same time calculates the analog input measurements in accordance to previous measurements and estimates if the motor should rotate to one direction or another to fix its position, as it should be. A web-camera captures continuous shots of the arm's physical position in the laboratory so that the operator identifies and verifies its exact position compared to the one determined by the potentiometer measurements presented on the graphical control interface.

[FIGURE 3 OMITTED]

The Robotic Arm System as an Educative Tool

In more detail, the system described is a powerful, multidiscipline tool that offers a variety of knowledge aspects to the students. The actual educative process could be separated into certain steps that the students follow. Those steps are based on modern educative processes and methods and were designed in cooperation with the University of Applied Sciences at Munster. The results of the pedagogical evaluation conducted there, where also taken into account to further improve the educative procedure.

In the beginning, students are presented with the web portal environment and are asked to navigate through the preliminary pages, which explain the course's structure and goals. Afterwards, students have to go through the basic coursework material which is published on the website and involves theory on electrical drives and motors and exercises based on that theory. The exercises are of the "multiple choice" nature and their web presentation is based on the PHP scripting language. This offers pseudo-interactive "student-tutor" support in the sense that, as soon as the student completes the exercises, the script checks all the incorrect answers, presents a score and--most importantly--suggests specific parts of the theory that should be revised to improve the student's performance.

As a succession to the first part of the theory and exercises, students proceed with studying motor control theory and robotics. Prior to the course-work material, a simple questionnaire determines if the students need introductory revision of transistors theory and applications and, when needed, relevant terms and theory are presented before the student can go on with the coursework material. Such material involves schematics of motor control circuits, robotics theory, terminology and applications as well as actual pictures of the circuitry, which will be used later, during the hands-on training. Once more, students are asked to train through exercises after having read the online material.

Moving further through the course, the robotic arm system is introduced to the students through series of photographic material and schematics as well as video clips of the robotic arm in use. Students can primarily work on the user interface of the control program. The user interface features simple graphical media such as buttons, knobs and position indicators and is accessed through the web portal, using any web browser, as if it were a web page. Students can exercise on the arm's control by operating the motion buttons and knobs and viewing the resulting movement as graphical indicators without physically controlling the robotic arm.

During the next step, the safety feature that isolates the control circuitry of the arm from the user interface is disabled so that students can control the actual robotic arm through the Internet. The resulting motion is captured by a web camera located beside the robotic arm and shows the different movements triggered by the students, thus experiencing the hands-on application of the studied theory.

In an attempt to take the course a step further into motivating the students' improvisational skills, based on the studied course, the web portal allows students to work on their individual robotic arm control programs and test them by loading them through the user interface, directly controlling the robotic arm with their implemented parameters and program structure. The security issues of such individual student control are discussed later.

The Multidisciplinary Nature of the System

The system's design covers a certain range of educational fields and can, therefore, be used for tutoring purposes in discrete, stand-alone courses. The following four points describe the multidiscipline nature of the system and the relevant areas of study it involves:

* Means of movement -- Motors: It is important for students of the electrical engineering field to have a general idea of the types of motors available and DC motors in specific, which are as a matter of fact the subject of one of their primary courses. Using the robotic arm, the students can observe the rotation of the motors and their reverse movement while changing the polarity of the voltage supplied to the motors' coil. Furthermore, it is a fine example of a modern application of motors in real life.

* Control of the motors: While studying the control of motors, students can perform practical control of the DC motors on the robotic arm, using the program and interface circuitry board. The H-Bridges are a fine example of motor control, illustrated as a circuitry board whose design and components the students can observe and study.

* Software-based control -- Programming: One of the courses relevant to electrical engineering is that of SCADA systems. SCADA is the acronym for Supervisory Control and Data Acquisition. SCADA systems are computer systems, which gather and analyze real time data. The computer program, which controls the robotic arm can be thought of as a SCADA program since it acquires data from the potentiometers of the arm's junctions to analyze it and present the position of each part of the arm. Students can navigate through the program's block diagram and study the data analysis performed during the program's execution as well as create their alternative programs to control the robotic arm.

* Robotics -- Theory and applications: It is obvious that while talking about robots, one cannot help but delve into the subject to have an accurate--though far from complete--idea of what they are working on. Terms such as "degrees-of-freedom" or "rotation angle" are studied by the students to understand the basic aspects of robotics. The determination of the position of each of robotic part is also an important feature in robotics. The robotic arm application plays a key role in robotics education since the student can observe the movement of the arm and comprehend why for example the more degrees-of-freedom a robot has, the better its flexibility and the more complex its control is. Robotics theory, though interesting it may be can prove to be rather dull for the student if such practical explanation and demonstration is absent.

Security Issues

The implemented software program for the control of the robotic arm works, evidently within predefined boundaries so that the system is safe from user maltreatment. This means that the program's structure features certain values over or under which the robotic arm axis seize to respond to the operator's input. These developer-specified values are continuously compared to the monitored voltage values from the potentiometers, which represent the position of each part of the arm. The figure (Figure 4) shows the program structure to perform such comparisons. Equal program restrictions apply to the self-developed student programs for the arm's control. Students are presented with a predesigned "console" program, which has preset movement, voltage, and current restrictions so that students do not succeed in moving the robotic arm to unwanted locations. Any attempt to exceed the voltage limit defined by the "console" will result into nonfunctionality of the loaded program.

[FIGURE 4 OMITTED]

EVALUATION OF THE SYSTEM

While implementing the e-learning system, certain guidelines where followed to ensure functionality and ease of accessibility to the platform. Experienced personnel including tutors and graduate students tested the system to collect comments and report drawbacks concerning its use.

More thoroughly, the technical completeness of the course was checked as well as the proper operation of the experimental process. The safety of the equipment was tested against miscalculated input values to observe the system's reaction and possible dysfunction. The user interface through which the user operates the robotic arm was tested to ensure operational clarity.

After obtaining satisfactory feedback from all relevant parameters tested, the robotic arm e-learning platform was tested by a group of twenty students who are studying electrical engineering at the Technological Education Institute of Kozani. They where asked to participate in a "virtual class" instead of taking one of the optional lessons from their study curriculum and provide the developing team with feedback on the class and its nature. The group was first presented with the website bearing the e-learning portal, which contained all theoretical material due for studying, arranged in thematic modules, from transistor theory and functions, to graphical programming and robotics.

The group followed the course either from their home computers or from the institute's internet room without a specific timetable but within a defined timeframe, which determines the amount of time that each theoretical section requires and imposes a deadline after which the section would be unavailable for studying, in an attempt to prevent students from piling up everything for the end of the trial period. Simultaneously, the robotic arm remote control system was functional for the students to exercise upon and online multiple-choice tests were available for those willing to test their knowledge that far.

Having used the e-learning platform, the group reported that they had gained significant knowledge on motion control and robotic applications, assisted by the robotic arm system which they thought of as "pioneering," "interesting to work with," and "a necessary companion to education." They also reported that the lesson was remarkable, due to the nature of its subject, the way of teaching was not framed within the borders of standard tuition, similar to other lessons. The use of technological means and laboratory applications based on the subject, helped students get better hold of the lesson and its theory.

Nonetheless, there was a noteworthy number of students who expressed their will to control the robotic arm while being in the laboratory where it is situated so as to view the outcome of their manipulation in real life if they were given the opportunity.

CONCLUSIONS

Discussing the educative benefits and the way they are delivered to the students, one should primarily state that the educational material is provided to the students in an entirely new approach. Although, it would be improper to describe existing distance learning methods as conventional, the portrayed e-learning platform is somewhat unconventional, compared to the earlier.

While studying through distance learning courses, students interact with their tutors remotely, participating in online classes, reading online material and "handing" over their essays and homework through the Internet. The platform featuring the robotic arm system is based upon similar models. The students can read or download online theoretical material concerning their class and interact with their tutor and among themselves. The concept that takes the method a bit further is that of the remotely controlled laboratory equipment, offering the students practical examples of the lesson they are studying and discussing. The opportunity to exercise and familiarize with the theoretical approach of the lesson is noteworthy. Students not only study and learn remotely through tutoring notes and texts but also practice on the subject by use of the electronic laboratory equipment, available remotely.

Presenting an accurate example, one could think of students who regularly--though not within a framed, compulsory schedule, rather on their desired time--visit the web portal of a robotics lesson where the tutor offers online notes and accompanying texts such as robotic terminology (degrees-of-freedom, dom, rotation angles, etc.) for the students to read as well as a proposed bibliography for even more comprehensive studying. Students are welcomed to study all pertinent material and submit any queries for the tutor to reply and explain. Afterwards, students are granted access to the robotic arm system to become acquainted with the principles of robotics and observe their real-life applications. At this point, students cannot but grasp the idea, for example, of what degrees-of-freedom of a robot are and what is the effect of creating a robot with either less or more degrees of freedom than the existing one.

As illustrated before, students not only become acquainted with robotics, the subject of the lesson whose tuition the e-learning platform assists but also delve into various scientific areas such as electronics, graphical programming, and network usability. It is, therefore, accurate to say that the platform supports tuition--and promotes the idea and profit of distance learning education--in a way both stimulating and innovative.

What is more, students profit from such an e-learning platform by being able to read, judge, and comment on their classmates' essays, all obtainable through the online platform's features. Further assistance is provided to the students since they can read through their classmates' work, getting ideas and help for their own assignments. Online e-learning platforms, thus, promote the idea of self-tutoring and cross-student-tutoring where students "teach," in a broad sense, their classmates, sharing their knowledge and making use of their rapid comprehension of a subject.

[FIGURE 5 OMITTED]

Furthermore, the electronic equipment is secure from the students, which in cases of sensitive instruments is a vital aspect, to avoid malicious use by inexperienced operators. Having to dispose of mistreated, damaged laboratory devices and obtain new ones while there is need for new and improved hardware is a depressing thought. Such instruments have no real exposure to the students since they are remotely operated, always within predesigned frameworks of functionality, and can be kept in safe places where only authorized service personnel have access.

As far as the educational institute is concerned, the vast abilities of e-learning have benefits which depend entirely on the resourcefulness of the tutors. The need for new or even existing classrooms is minimized, since one server computer may host numerous platforms for online courses and disciplines whereas conventional tuition would demand significant space for the classes and students to be hosted. In the example where the group of students tested the robotic arm system and e-learning platform, significant decrease of students willing to visit the laboratory for study in the first place was observed but as stated, some students afterwards thought that it would be even more exciting for them to be in the laboratory in the event of further control of the arm.

Summarizing the case, it is imperative to emphasize the necessity for future distant learning courses to track the idea of remote laboratory access and enhance their platforms with such educative tools. Distant learning, by definition, is an intricate and difficult issue where students are asked to prove their skills and degree of knowledge acquired through indirect education. Therefore, it is crucial to make the whole procedure as direct as possible and simulate it to any available extent to the conventional educational process of direct tuition. Creating a close simulation to direct education, results in more efficient and competitive knowledge acquisition. While trying to achieve this, one should have in mind that practical examples and applications of the studied subject motivate students for further study on their own and formulate a more attractive attitude towards education.

References

Bugscope Project. (1999). Retrieved October 4, 2006, from http://bugscope.beckman.uiuc.edu

eMerge Project. (2002). Retrieved October 4, 2006, from http://www.emerge-project.net

National Technological University. Retrieved October 4, 2006, from http://www.ntu.edu

RETWINE Project. (1998). Retrieved October 4,2006 from http://www.isoc.siu.no/isocii.nsf/projectlist/56426

Notes

* Distance Learning Resources -- http://www.academicinfo.net/eddistcourses.html

* Distance Education at a glance -- http://www.uidaho.edu/eo/distglan.html

* LSTN Engineering Journals -- http://www.engsc.ac.uk/er/journals/index.asp

NIKOLAOS D. ASIMOPOULOS, KYRIAKOS IL. NATHANAIL, AND VLASIOS I. MPATZAKIS

Technological Education Institute of West Makedonia, Greece

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