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Virtual Laboratory for Creative Control Design Experiments Suzana Uran, Member, IEEE, and Karel Jezernik, Senior Member, IEEE
Abstract—This paper proposes a two-step strategy for the computer-aided learning of control. A virtual Web-based laboratory for control design experiments (http://www.hl1.uni-mb.si), which supports a two-step strategy, is based on the MATLAB Web server (MWS) and consists of two virtual laboratories. The first virtual laboratory, called “Web sisotool,” supports computer-aided control design and structured hands-on experiments. Computer-aided control design is welcome as a design tool while structured hands-on experiments are welcome for the visualization of hard-to-grasp concepts. The second virtual laboratory offers students an unstructured MATLAB-like environment, called “M-file application,” that allows students to create and design control design experiments by writing MATLAB M-files of their own and executing them on MWS. The presented virtual laboratory for control design experiments is cost effective and has already been successfully used for the learning of control. Student feedback is also presented. Index Terms—Bode plot, computer-aided design, control design learning, M-file, MATLAB Web server (MWS), structured hands-on experiments, unstructured environment, virtual laboratory.
I. INTRODUCTION N introductory control systems course is given in the third year of study at the Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia, for students from different study areas: electronics, automation, and mechatronics. This course is available during the academic year, once in the autumn and once in the spring. On each occasion, approximately 15–20 students are enrolled in the course. When the students begin the course, their background knowledge consists of basic mathematics, physics, electrical engineering, electronics, and programming. Topics covered in the introductory control systems course are as follows: • input-output and state space description of single-input single-output (SISO) control systems; • development of block diagrams for SISO control systems; • quantitative and qualitative analyses of SISO control systems; • frequency domain control design techniques (Bode plot, Nyquist plot); • the Root–Locus design method; • state space controller design.
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Manuscript received June 5, 2006; revised July 11, 2007. The authors are with the Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia (e-mail:
[email protected];
[email protected]). Digital Object Identifier 10.1109/TE.2007.906599
The objectives of the introductory control systems course are as follows: • to teach students control design basics and computer-aided control design; • to support learning by doing; • to show students how to learn by Web and how to use it; • to minimize the gap between control theory and practice, by teaching control implementation, and using rapid control prototyping tools. Today, especially in the learning of control basics, the emphasis is not on what to teach, but on how to support active learning and to use high efficiency computer tools. Computer-aided control design and control implementation are desirable because they improve the efficiency of control learning and industrial control practice. Web-based learning is also desired. Several virtual laboratories have been built based on MATLAB covering a variety of topics [1]–[4]. In addition to these virtual laboratories, others incorporating or devoted to control basic topics are presented in [5]–[8]. In [5]–[7], the control topics cover modelling, system representations with time responses or frequency responses, the relationship between open- and closed-loop systems, and Bode plot loop-shaping to design a controller. The main goal of virtual labs is the visualization of certain special phenomena or hard-to-grasp concepts, an illustration of course material and the important relationships within it, the elimination of math representations, and hands-on experimenting to support learning, as stated in [1]–[3] and [5]. The virtual laboratories in [5] and [8] are implemented in MATLAB using MATLAB graphical user interfaces (GUIs). In [6] and [7], virtual laboratories with control experiments published on the Web and implemented using Applets are presented. Very interesting topics with problems encountered in Bode plot teaching/learning are discussed in [8]. According to the references, it could be stated that computerization and information technologies affect learning methods considerably. A two-step strategy for the learning of control based on virtual laboratories is proposed in Section II. This strategy is based on a gradual change from less creative and structured to fully creative and unstructured learning environments. At the same time the two-step strategy supports a shift to exclusive computer-aided control learning. In Sections III and IV, two MATLAB Web server (MWS)-based virtual laboratories for control design experiments are presented, which support the two-step strategy for the learning of control. The virtual laboratories for control design experiments presented in this paper can be found at Internet address http://www.hl1.uni-mb.si. Student feedback is considered at the end of the paper.
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II. WEB-BASED VIRTUAL LABORATORY VERSUS MATLAB Among the objectives of the introductory control systems course are the learning of computer-aided control design and computer-aided control implementation. Many reasons exist as to why computer-aided control design and implementation are desirable in industrial practice, and in the learning of control design. First, the nature of the control design process is cyclic. To design a control system in industrial practice one must iterate through modelling, design, simulation, testing, and implementation as many times as required. Today’s market competition results in a demand for greater and greater efficiency. This demand for greater efficiency in the field of control practice is reflected in a need to perform control design and implementation as quickly as possible. Since many control design methods are graphical, the control design process could be speeded-up by using computers with suitable software to plot graphs instead of plotting them by hand. Computers are also used to perform simulations to validate a control plant model and a designed control for the plant. In addition, rapid control prototyping computer software tools are used to speed up the testing and implementation of control in industrial practice. For all the afore- mentioned reasons computer-aided control design and implementation is a must in any successful control education of students. Actually, the need for computer-aided control design and implementation was realized long ago by teaching communities at universities around the world. Therefore, laboratory practice in control has been adapted to teach students computer-aided control design and implementation using, for instance, MATLAB. MATLAB was, and still is, one of the software tools used at Universities all over the world to support the learning of computer-aided control design and implementation. However, lectures, theoretical exercises, and examinations in control have remained rooted in drawing (sketching) different plots by hand, while MATLAB was just an additional aid [9], [10]. Why? Multiple reasons exist as to why lectures, theoretical exercises, and examinations were not supported by MATLAB. • A student starting to study automatic control is usually a beginner in MATLAB, in a sense a “double beginner.” • Additional costs appear when introducing computer-aided learning of control design and implementation (computers and software need to be bought). • Time is needed to make a shift in human thinking, to gain more experience with computer-aided teaching/learning, and to develop Internet and Web-based technologies. MATLAB is a high programming language with good graphics and help, aimed at being user-friendly and easy to program. Unfortunately, teaching practice has shown that students need time to adopt the MATLAB definition of polynomials as a form of polynomial coefficients vectors. A permanent source of student confusion is whether the polynomial coefficients should be defined in descending or ascending powers of s. Students are also confused if one or more powers in the polynomial are missing. In addition, round and square brackets, commas, and semicolons must be used in the proper way. The MATLAB syntax is strict; nothing incorrect is allowed. All special visualization effects have to be programmed. Every teacher introducing MATLAB to support lectures must face
the risk that students will not see “the wood for the trees” in any control lecture given because of MATLAB. Therefore, one is wise to avoid a “double beginner” situation. References [1]–[7] show that building a virtual laboratory with an intuitive man-machine user interface is possible to decouple MATLAB programming and demanding mathematical representations from the control knowledge. Such a virtual laboratory could, at the same time, support “What if?” questions and hands-on experimentation. Therefore, the virtual laboratory is welcomed in supporting lectures. In learning control, a typical example of a plot drawn by hand is a Bode diagram. In [8], the authors argue that students must learn to draw Bode diagrams using piecewise-linear asymptotic approximations by hand to understand fully how the locations of poles and zeros affect the shape of the Bode diagram. This argument exists even though programs, such as MATLAB, can accurately create a Bode diagram for a given transfer function. A similar statement is given in [9]. The authors of [8] also state that teachers are faced with a problem that drawing semilogarithmic graphs by hand is inaccurate, whether on a blackboard (chalkboard), whiteboard, or an overhead transparency. An alternative to hand-drawn graphs are paper handouts with worked examples. Unfortunately, such paper handouts are good for accuracy reasons, but are not useful for answering a student’s “What if?” question. Therefore, in [8] the authors propose an aid—a special graphical tool (GUI) to draw piecewise-linear asymptotic approximations of Bode diagrams using MATLAB and a computer. Consequently, virtual laboratories for computer-aided learning of control design using Bode diagrams, piecewise linear or accurate, are welcomed. Additional costs are inevitable with a shift to computer-aided learning of control design. When the decision to teach exclusive computer-aided control design is made, the computer and suitable software must be available to each student at any time and in any place (at home for homework and learning, and at the university). The computer and software must be available especially during examinations and other types of assessment. Traditionally, each student owns a computer and has Internet access. Therefore, only the software costs are to be discussed in the following. MATLAB is taken as example. Many possibilities exist for the sharing of MATLAB costs between the student and the university. One possibility is that a student buys a student license, and the university buys an academic classroom license. Although this type of cost sharing seems to be straightforward, it is not. To obtain a student license, some involvement by the university is desirable. In addition, software update might attract problems if it is not synchronized between the student and the university. Another possibility is that a university buy a Network concurrent license and delivers MATLAB to a student using Internet in a remote client configuration at the site of university and at home. The university should decide how many license keys are needed. Yet another possibility for the university is to use MWS and accompanying license. MWS is a toolbox accompanying MATLAB6.5. Buying a MWS license (only one license needed), the licensee is entitled to publish on the Web MWS based applications, complying with Web application restrictions, to an unlimited number of Web browser clients at no cost for use by third parties (students). In the case of the
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newest MATLAB versions, the MWS license is replaced with a network concurrent license or designated computer license (article 8 of deployment addendum in [16]). The latter two solutions for the sharing of MATLAB costs are related by cost/performance tradeoff. The Network concurrent license gives full MATLAB performance including interactivity, but, at the same time, it is more expensive than the MWS version. Using a MWS, a Web-based virtual laboratory could be built and offered on the Web. Instead of MATLAB GUI, a Web-based user interface could be developed for any MATLAB application. Web technology is developing very fast and is very convenient for the delivery of learning material. The successful application of Web-based virtual laboratories [6], [7] show that on the basis of applets, Web applications with intuitive man-machine communication could be developed. In the following, two MWS-based laboratories and their user interfaces are explored. Web-based virtual laboratories present a good solution to many problems encountered when a shift to computer-aided learning of control takes place. The use of virtual laboratories enables the visualization of special phenomena or hard-to-grasp concepts, the illustration of course material, and a focus on important relationships inside the course material. In addition, virtual laboratories enable the elimination of mathematical representations, computer programming, and the problem of “double beginner”. At the same time virtual laboratories with an intuitive man-machine interface enable hands-on experimentation to support learning without a need for an instructor. Virtual laboratories for control design also eliminate the need for the hand drawing of different plots, such as Bode plot and, thereby, support better understanding and speed up control design. Web-based virtual laboratories are desirable because of their availability at any time and in any place, ease of delivery, cost optimality on the university side, and no cost on the student (client) side. If needed, virtual laboratories for control design should also be available during examinations or other types of assessment. Finally, to achieve intuitive man-machine communication or some special effect of visualization, the unstructured MATLAB development environment has been replaced by the relatively structured experiments of virtual laboratories. What parameters could be changed within which range and what could be observed or designed in a particular experiment is defined by the structure of the virtual experiment or the virtual laboratory environment. Consequently, students could not perform virtual experiments beyond the given structure; therefore, they cannot create and design experiments of their own. However, engineering education must ensure that young engineers possess the ability to add new value; to design and conduct experiments; to analyze and interpret data; to design a system, component, or process; and to meet the desired needs [11]. Problems students would have to solve in their professional career are not likely to fit into one of the structured experiments the students have learned at school. Therefore, a permanent need in engineering education exists for less structured and more creative environments where students can build experiments of their own, and practice design, data analyses, and interpretation. A two-step strategy for the computer-aided learning of control design is proposed. In the first step, the learning of control is based on
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structured experiments in a virtual laboratory to gain understanding. In the second step, students learn the skills needed to design and create experiments of their own in an unstructured environment. Two virtual laboratories for control design were built to support the two-step strategy. The first virtual laboratory, called “Web sisotool,” is a standard MWS application with a structured environment. The “Web sisotool” was built to support computer-aided control design and is represented in Section III. The second Web-based virtual laboratory is called “M-file application” and is presented in Section IV. “M-file application” is an unstructured batch mode programming environment, similar to MATLAB, that enables students to write their own M-code for MATLAB and to create and design their own MATLAB experiments. The term unstructured environment (experiment) is used in the paper in the sense that no structure, for instance, control-loop structure or inputs regarding the control experiment to be performed, is given in advance. III. MWS AND WEB SISOTOOL MWS and its dependency on computer platforms is considered in [13]. MWS-based MATLAB applications use the capabilities of the World Wide Web to send data to MATLAB for computation and to display the results in a Web browser. MWS depends upon transmission control protocol/ Internet protocol (TCP/IP) networking for data transmission between the client system and MATLAB. The simplest configuration is used, in which a Web browser runs on a client personal computer (PC), while the MWS and the Web server daemon run on a server machine. The MWS used is configured on an Apache Server. Currently, a MATLAB 6.5 release 13 and the accompanying MWS are used. MWS [15] applications are a combination of M-files, hypertext markup language (HTML) documents, and graphics. Two HTML documents are needed. The first HTML document collects the input data from the user, sends them to the MWS, and runs an M-file needed for the application. The M-file needed for the application resides permanently on MWS. Later, this m-file will be referenced as an application M-file. The application M-file reads input data collected by the first HTML document from a MATLAB structure, performs requested operations, generates requested graphics, and places the output data into the MATLAB output structure. The second HTML document gets results from the MATLAB output structure and displays them on the client machine. (For detailed information, see [15].) Previously described applications will be referenced as the standard MWS applications, as opposed to M-file MWS applications (also M-file applications for MWS) offering an unstructured MATLAB environment. A. Web Sisotool—An Example of Standard MWS Application “Web sisotool” application is an example of a virtual laboratory for the learning of computer-aided control design. The Web page of the “Web sisotool” application is shown in Fig 1. The idea for this application comes from the MATLAB tool called “sisotool.” Using the “Web sisotool” application P, PI, PD, PID, and other controllers could be designed using Bode plot or Root–Locus method. The structure of the treated control
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Fig. 1. Web sisotool application.
loop is shown in the right upper corner of the Web page. The control loop consists of three transfer functions: an input filter F, a controller C, and a control plant G. In the Web sisotool application, the order of the transfer functions F, C, and G is limited to three to keep the input data and results visible on one Web page. The third order of transfer functions is sufficient for the introductory control course. Transfer functions F, C, and G are defined in the form of polynomials. The powers of polynomials are visualized on the Web page to enable user-friendly input of transfer functions. Two graphs are shown at the same time (Fig. 1) on the Web page. Time response and Root–Locus or Bode plot of various transfer functions could be selected in the menu and shown on the two graphs. Among the various transfer functions that could be selected for time response, Root-locus or Bode plot are transfer functions F, C, G, open-loop transfer , and a closed-loop transfer function with and function without F. “Web sisotool” supports visualization of Bode plot design parameters (phase margin and crossover frequency) and reading of the actual values of the amplitude and phase values of the Bode plot at a given frequency. Any variation of the parameters on the Web page results in a new updated figure on the screen. Therefore, control-loop or control-plant behavior could be interactively explored. Controller design and tuning for various types of plants and controllers could also be performed. By observing closed-control-loop time response and Bode plot with visualized phase margin and crossover frequency, students could grasp the relationship between time-response and Bode plot design parameters. Strict limits on those experiments that could be performed are imposed by the structure of “Web sisotool.” These limits are the given structure of the control loop, the order of a control plant, and a controller. Only input step response can be observed; multiple Bode plots or time responses cannot be observed at the same time, etc. Therefore, creativity in a structured environment
is considered to be low, and a virtual laboratory with unstructured environment is needed in addition. IV. M-FILE APPLICATION According to the two-step strategy for computer-aided control design learning, proposed in Section II, a virtual laboratory with an unstructured environment is needed in addition to the virtual laboratory with a structured environment. MATLAB in a remote client configuration (Section II) could be used for this purpose. In this case, one license key is needed per one active user because of the interpretative nature of the MATLAB development environment. Another option is to use MWS to implement an unstructured MATLAB environment that would run MATLAB M-script programs in the batch processing mode, while M-script programs would be developed in some other environment. In the latter case, multiple active users could be effectively served with only one Web server license key. Therefore, an MWS-based option is an interesting consideration because of lower costs. The following considers a virtual laboratory based on MWS running MATLAB M-scripts in the batch processing mode. An unstructured MATLAB programming environment was implemented using a virtual laboratory, called “M-file application.” “M-file application” was built having in mind a student beginner in MATLAB. Therefore, the main objective of the virtual laboratory is that MATLAB M code written for the virtual laboratory could be without any changes successfully executed with MATLAB running locally on the PC. Vice versa is not always possible because of limitations imposed on the “M-file application.” To comply with MWS license restrictions, limitations that encompass the size of the user M-file (2 k B) and the processing time of the user M-file (maximum 1 min) were imposed on the M-file application. In addition, “M-file application” supports only one figure per M-file and tf class of transfer functions.
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Because of its limitations “M-file application” is only suitable for learning experiments, since the M-files might only be of the size of the demonstration programs. The “M-file application” allows students (users) to write their own M-files and send them to MWS for execution. Students obtain the results over the Web. To use the “M-file application,” students need only an Internet browser and any of the text file editors, i.e., the Notepad. The concept of an unstructured MATLAB environment implementation proposed in the paper is to build one standard MWS application that would serve for the uploading and execution of users’ M-files on MWS. The size of the user M-files file that could be uploaded is limited to 2 k B. All user data should be defined inside the user M-file. No input of user data is available through the Web page. A constraint of one figure per user M-file for M-file application is accepted. Temporarily, only the object tf (transfer function) is supported by the “M-file application.” Hypertext preprocessor programming (PHP) language and a multithreaded, multiuser structured query language (MySQL) database were chosen for the implementation of the M-file application. PHP [14] is an open source server-side language used to create dynamic Web pages. The PHP programming language was chosen because PHP could be mixed with the HTML. For the standard MWS application, two HTML files are needed and the application M-file, as described in Section III. In the M-file application, the first HTML file is replaced with two PHP files. The task of the first PHP file is to upload the necessary user M-files. Up to three user M-files can be uploaded to the MWS at the same time, if needed. The second PHP file serves as a reservation for the user directory on MWS, for the saving of uploaded user M-files to the user directory, for sending a user directory name and a name of user M-file to be executed as application data, and for running the application M-file on MWS. The reservation for user directories is based on the user TCP/IP address and on MySQL database. Only one user can access MySQL database at the same time; therefore, two users cannot reserve the same user directory. After the user has reserved the user directory, all user’s M-files are saved on the user directory. The application M-file is a function that runs users M-files and saves results to the application directory. At the end of application M-file, the second HTML file is called, and the results are sent to the second HTML file. In “M-file application,” the second HTML file notifies the user that the MATLAB has finished the execution and calls the third PHP file. The third PHP file releases the reserved user directory, deletes all user M-files, and displays the results in the browser. Figs. 2–4 show the whole M-file application as seen by the user, in the case of a very simple task of plotting a step response of a transfer function. In Fig. 2, a simple code for the calculation of step response, written in the text editor Notepad, is shown. Fig. 3 presents the Web page for the uploading of M-files. Fig. 4 shows the Web page with numerical and graphical results for the uploaded user M-file. The graphical results are represented in the form of a figure. All the variables used in the user M-file can be selected from the selection menu to be displayed. For M-file MWS application, the use of Internet Explorer, as a browser, is recommended but not necessary. A good as-
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Fig. 2. M-file for a step response.
pect of the proposed solution is that using the Internet Explorer, the MATLAB M-code syntax errors are reported to the user. Not all problems are solved with the proposed solution. One of the problems remaining represents the interactive action of the MATLAB environment. In the user M-file to be executed by MWS, every command must end with a semicolon; otherwise, the browser reports error; and the M-file execution is terminated. The “M-file application” is supported by an introduction to MATLAB and MATLAB command reference in Slovene. In an M-file, application environment students recreate one or two experiments previously performed in Web sisotool. Afterwards, students could be asked to show their creativeness by creating and designing an experiment that was impossible to perform using Web sisotool, for example checking load-step response or showing a family of time responses’ in one figure or designing a state space controller, etc. Reference [12] presents a solution, called the extension of MWS, similar to the “M-file application.” The extension of MWS automatically creates a standard MWS application for each uploaded user M-file. The user M-files, uploaded as a text from the Web or as a text file, are stored in a MySQL database and preprocessed. The output results could be graphical (one or more figures) or numerical. The input of user data for extension of MWS is foreseen over the Web browser. The user input and output variables have to be an element of sinput (input) and soutput (output) structure, respectively, to be recognized as input/output variables by the automatic algorithm of the extension of MWS. Consequently, the extension of MWS [12] is unsuitable for students starting to learn MATLAB in which all the names of variables are allowed except reserved words. In [12], no report is found about user M-file syntactic error(s) handling, and no report about whether multiple M-files could be uploaded and run. Another drawback of the extension of MWS is that a considerable amount of code has to be generated for each uploaded user M-file that may result in memory troubles. V. STUDENT FEEDBACK In the spring semester of the school year 2005–2006, the virtual laboratory for control design experiments was used in the Control Systems course at the Faculty of Electrical Engineering and Computer Science, University of Maribor. Seventeen students were enrolled. At the beginning and in the middle of the Control Systems course, only the “Web sisotool” was used. At the end of the course, “M-file application” was used to create and design control experiments. Students were asked to fill in a questionnaire with six questions (shown in Table I) about the two virtual laboratories at the end of the course. Sixteen students completed the form.
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Fig. 3. M-file upload to MWS.
Fig. 4: Numerical and graphical results for M-file in Fig. 2. TABLE I QUESTIONS IN THE STUDENT INQUIRY
The questionnaire showed the following. • Eight students used M-file application only at school and the remaining eight students used M-file application at school and at home. • The answers to the second and the third questions were similar and stated that Internet connections fre-
quently did not work, work with M-file application is slow, and more MATLAB documentation would be welcomed. • Ten students prefer to use M-file application, three students prefer “Web sisotool,” and three students did not answer the question.
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• Ten students recommended M-file application for a beginner, four students did not recommend, and two students could not decide. • Good aspects of M-file application are no need for a student license and good availability. The student inquiry showed that some work has to be done regarding the reliability of the MWS over the Internet. The majority of students preferred the unstructured environment of the “M-file application” rather than the “Web sisotool.” VI. CONCLUSION A virtual laboratory for control design experiments based on MWS was successfully used during a Control Systems course in the spring semester 2005–2006 at the Faculty of Electrical Engineering and Computer Science, University of Maribor. A virtual laboratory “Web sisotool” with structured experiments was used first to support exclusive computer-aided control design (also examinations) and to gain understanding of design. Then a virtual laboratory with an unstructured environment “M-file application” was used where students could create and design their own control experiments. A student inquiry showed that students preferred the unstructured environment of the “M-file application.” ACKNOWLEDGMENT The authors would like to thank J. Otiˇc, E. Urlep, and S. Zapuˇsek for their help and effort in developing MWS applications.
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[6] S. G. Crutchfield and W. J. Rugh, “Interactive learning for signals, systems, and control,” IEEE Control Syst. Mag vol. 18, no. 4, pp. 88–91, Aug. 1998 [Online]. Available: http://www.jhu.edu/~signals [7] J. S. Lee and D. R. Yang, “Chemical engineering education using Internet,” in Proc. 8th APCChE Congress, Seoul, Korea, 1999, pp. 1033–1036 [Online]. Available: http://www.chbe.gatech.edu/lee/ che4400/javamodule.html [8] E. Cheever and Y. Li, “A tool for construction of bode diagrams from piecewise linear asymptotic approximations,” Int. J. Eng. Educ., vol. 21, no. 2, pp. 335–340, Mar. 2005. [9] C. T. Chen, Analog and Digital Control System Design: Transfer-Function, State-Space, and Algebraic Methods. New York: Saunders College, 1993. [10] R. C. Dorf and R. H. Bishop, Modern Control Systems, 7th ed. Reading, MA: Addison-Wesley, 1995. [11] S. D. Creighton et al., “A comprehensive system for student and program assessment: Lessons learned,” Int. J. Eng. Educ., vol. 17, no. 1, pp. 81–88, Jan. 2001. [12] M. Sysel and I. Pomykacz, “Extension of MATLAB web server,” in Proc. 35th IASTED Int. Conf. Advances in Computer Science and Technology, St. Thomas, U.S. Virgin Islands, Nov. 2004, pp. 70–74. [13] A. Pester and R. Ismailov, “Interactive applications in teaching with the MATLAB web server,” in Proc. Vestnik National’nogo Techniceskogo Universiteta “KchPI”, Kcharkiv, Ukraine, 2001, pp. 14–19. [14] M. Zandstra, SAMS Teach Yourself PHP in 24 hours, 3rd ed. Indianapolis, IN: Sams, Dec. 2003. [15] The MathWorks Inc., MATLAB Web Server, Product Documentation, Jan. 2001. [16] The MathWorks Inc., Software License Agreement for Matlab 2006b, Sep. 2006. Suzana Uran (S’96–M’04) received the B.Sc., M.Sc., and Ph.D. degrees in electrical engineering from the University of Maribor, Maribor, Slovenia, in 1985, 1989, and 1998, respectively. She is currently an Assistant Professor at the Institute of Robotics, Faculty of Electrical Engineering and Computer Science, University of Maribor, where she has been since 1985. Her research activities include control, robot position/force control, Web-based education in control, and robotics.
REFERENCES [1] B. Wittenmark, H. Haglund, and M. Johansson, “Dynamic pictures and interactive learning,” IEEE Control Syst. Mag., vol. 18, no. 3, pp. 26–32, Jun. 1998. [2] B. L. Sturm and J. D. Gibson, “Signals and systems using MATLAB: An integrated suite of applications for exploring and teaching media signal processing,” in Proc.. 35th Frontiers in Education Conf., Indianapolis, IN, Oct. 2005, pp. F2E-21–F2E-25. [3] M. de Magistris, “A MATLAB-based virtual laboratory for teaching introductory quasi-stationary electromagnetics,” IEEE Trans. Educ., vol. 48, no. 1, pp. 81–88, Feb. 2005. [4] J. Sanches et al., “Easy java simulations: An open-source tool to develop interactive virtual laboratories using MATLAB/Simulink,” Int. J. Eng. Educ., vol. 21, no. 5, pp. 798–813, Sep. 2005. [5] M. Johansson, M. Gäfvert, and K. J. Aström, “Interactive tools for education in automatic control,” IEEE Control Syst. Mag., vol. 18, no. 3, pp. 33–40, Jun. 1998.
Karel Jezernik (M’77–SM’04) received the B.Sc., M.Sc., and Dr.Eng. degrees in electrical engineering from the University of Ljubljana, Ljubljana, Slovenia, in 1968, 1974, and 1976, respectively. He was a Visiting Research Fellow at the Institute of Control, Technische Universität Braunschweig, Braunschweig, Germany, from 1974 to 1975. In 1976, he joined the University of Maribor, Maribor, Slovenia, where he has been a Full Professor and Head of the Institute of Robotics since 1985. His research and teaching interests include automatic control, robotics, power electronics, mechatronics, and electrical drives. Dr. Jezernik is a member of the Electrotechnical Association of Slovenia and the Automation and Robotization Society of Slovenia. He has acted as a member of several programming and steering committees at international and national conferences. He served as IEEE IES Officer–Vice President for Workshops from 2002 to 2004, Vice President for Technical Activities from 2005 to 2006, and Senior AdCom member since 2007.
