Ciclope Robot: Web-Based System to Remote Program an Embedded Real-Time System

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 56, NO. 12, DECEMBER 2009

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Ciclope Robot: Web-Based System to Remote Program an Embedded Real-Time System Diego López, Raquel Cedazo, Francisco Manuel Sánchez, Member, IEEE, and José María Sebastián, Member, IEEE

Abstract—This paper presents a particular case of a pedagogically successful, dynamic, and efficient remote laboratory. The aim of the remote laboratory is to learn how to program embedded real-time systems in a real machine such as a robot. The system supplies feedback information to the user through a web browser and an ssh terminal. Likewise, the remote laboratory allows a high degree of interaction owing to a clear and simple interface. This type of telecontrol web-based system generates strong interest among students. The following are the two main contributions of this system: The remote laboratory allows collaboration among students in order to solve the problem, and the usage of a free software architecture allows anyone to replicate and improve the laboratory. Index Terms—Distance learning, real-time systems, remote laboratory.

I. I NTRODUCTION

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Fig. 1. One of the two workstations available in the laboratory for DDCS subjects at UPM-FI.

Manuscript received April 7, 2007; revised September 11, 2008. First published October 31, 2008; current version published November 6, 2009. This work was supported in part by the Ministerio de Educación y Ciencia Español under Grant TSI-2004-04032 and in part by the Comunidad de Madrid under the ASTROCAM Project: Astrophysics Network of the Comunidad de Madrid (S-0505 ESP-0237). D. López, R. Cedazo, and F. M. Sánchez are with the Facultad de Informática, Universidad Politécnica de Madrid, 28660 Boadilla del Monte, Madrid, Spain (e-mail: [email protected]; [email protected]; [email protected]). J. M. Sebastián is with the Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain (e-mail: [email protected]). Digital Object Identifier 10.1109/TIE.2008.2007007

have to design an embedded real-time system in order to control an industrial robot. Nowadays, several distance-learning tools and methods are being developed by different authors [3], [6]–[10], and there are several research projects about how to structure the courseware [11], how to customize a remote-user system [12], or how to create workspaces with simple user interfaces to exchange information [13]. Likewise, there are other telecontrol projects that—although not applied to education—nevertheless, can be directly applied in remote laboratories [14]–[16]. The aim of the Ciclope Robot [17] is to offer students access to the real laboratory and to control it via the Internet using a normal web browser. The main advantage is that the laboratory is available round the clock every day of the year. Restrictions of time and scheduling are resolved by using the Ciclope Architecture [18], [19] which has been designed for building remote laboratories [20]. This architecture allows us in building web laboratories, which can work standalone or can be integrated into any learning web environment. So far, Ciclope Robot runs in standalone mode. Another advantage of the system is that the Ciclope scheduling allows the laboratory to be shared by different subjects, faculties, and even by other universities from anywhere in the world. Many other studies have been reported in the literature utilizing web-based remote technologies to handle real physical experiments [21]–[36]. However, they do not offer the option of replicating or improving the remote laboratory with contributions from other teachers or students, unlike the Ciclope Robot whose main feature is the exclusive use of free software and free

EB TECHNOLOGIES have been widely applied to education since 1990 [1]. Web-designed laboratories and projects not only guide learners to a better understanding of abstract theories but also build up their practical skills and improve their ability to analyze and solve problems [2]. There is a demand for this kind of knowledge in the information technology society; however, it cannot replace traditional learning for several reasons [3]. Nevertheless, the industry demands engineers who are able to solve complex problems and face the changes in their professional career. This work methodology is suitable for proper training in real cases [4], [5]. The main problem is the lack of resources, and even when resources are available, there may be a shortage of personnel or material in order to allow access to laboratories. As a result, when laboratories are available, access is often restricted to certain periods of time while the laboratories remain unused during the rest of the time, even though they could be put to good use by other departments in the same university. A case in point is the subject Design of Discrete Control Systems (DDCS) with a laboratory consisting of only two workstations as shown in Fig. 1. In this laboratory, the students

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Fig. 2. Architecture of the Ciclope Robot system.

Fig. 3. Physical scenario of web laboratory.

hardware for building a remote laboratory. The Ciclope Robot is distributed under the GPL licenses [37]. The physical laboratory is located at the Facultad de Informática (FI) of the Universidad Politécnica de Madrid (UPM), Spain. II. S YSTEM D ESCRIPTION This practical laboratory was designed as part of a Master degree thesis [38] in 2001 and was presented at the WRTP congress [39] in 2002. This laboratory has been used for six consecutive academic years in the subject DDCS. For reasons of limited space, the Ciclope Robot laboratory started running in the 2005–2006 academic year. Fig. 2 shows a global view of the Ciclope Robot system, with the key components and the communication architecture, and Fig. 3 shows the actual setup which is controlled via web. This is a client/server architecture where the client is any computer with any kind of browser, which lets students access the remote laboratory through the Internet. The server is the development PC, which is located in the remote laboratory and supplies all the services.

The physical laboratory is composed of two PCs, one for development and the other one for execution, called the target PC. Both computers belong to the same local area network (LAN). Other main components are the following: 1) a Fisher–Technik toy industrial robot arm, controlled by an I/O PCI card plugged into the target PC; 2) a motorized rotating table controlled by the development PC, where pieces that the robot has to move are located; it offers four sets of pieces; 3) two web cameras for observing robot movements; 4) a lighting system (bulb) which ensures visibility at all times. The client remotely accesses the development PC, writes a program, compiles it, and turns the target PC on or resets it. The target computer, on which the control programs are run, does not have a hard disk and therefore needs to boot via the network. When it boots, it makes a request through the network to a DHCP server, installed in the development PC. Therefore, the target PC receives the program to be run, which is the Real Time Executive for Multiprocessor Systems (RTEMS) [40] real-time operating system with the application program embedded in it. The robot is connected to the target via an I/O PCI card, and it carries out the programmed movements. The client has to implement a program that places the pieces of the rotating table in specific positions, as will be explained later. III. H ARDWARE A RCHITECTURE The key hardware components are described in the following sections. A. Fisher–Technik Industrial Robot Arm Fig. 4 shows the robot arm used. It has an amplifier card, designed by Rica [38] as part of his Master degree thesis. This card is connected to a digital I/O PCI card which is plugged into the target (as shown in Fig. 5). The robot has 4 DOF, as shown in Fig. 6: turn, height, depth, and grip. Each degree of freedom has two switches: one detects

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Furthermore, it has a network card and the Apache web server in order to allow communication with any client through the Internet. It will also communicate through the LAN with the target PC.

C. Target or Execution Computer

Fig. 4.

Toy robot arm used in the practical laboratory.

The target PC is the computer on which the control program, designed by students, runs embedded with the RTEMS operating system. In an industrial application, the target PC should be an onboard PC; however, for our educational purposes, it is an old PC with an Intel 486 microprocessor at 100 MHz. It does not have any hard disk; therefore, it boots from its network card and runs the program built in the development PC. Each time the program is modified, the target PC must be reset, and it automatically loads the new operating system with the application program embedded. A digital I/O PCI card is connected to this computer in order to control the amplifier which drives the motors and in order to read the switches (see Fig. 5). D. Rotating Table The table, as shown in Fig. 2, is used to offer the robot a new set of pieces to handle. In this experiment, if a piece drops outside the workspace, it is impossible to put it back in place remotely. Therefore, a new complete set of pieces can be supplied. This is achieved using a servomotor to rotate the table around 360◦ . A total of four sets can be supplied. Each time the table rotates in order to get a new set of pieces, an alarm is sent to the staff who will set them again. If the four sets of pieces are not in place, the students can continue working. However, they cannot do real tests until the pieces are back in position. The rotating table’s servo is connected to one of the free outputs of the servo controller, which is able to drive up to eight servos. This controller is commanded by an RS232-C port via the development PC.

Fig. 5.

Motor drive and I/O card.

the home position and the other is activated four times per motor turn. The control program needs to move each motor toward the home position and, afterward, counts and uncounts the pulses in order to know the current position of each axis. B. Development Computer The development computer is the PC where the students work together in order to reach their final objective: controlling the robot. The PC currently used is an Intel Pentium 4 microprocessor at 2.4 GHz, with a hard disk of 100 Gb and GNU/Linux Operating System with Debian 2.6.9 kernel version. It is installed with the RTEMS cross compiler which offers interfaces in Ada and C/POSIX. Its compiler is GNU GCC.

E. Cameras Two web cameras are connected to the development PC via USB. They give high-quality images for video conferencing and audio transmission. The cameras are fixed and cannot be moved remotely, so they have been placed in a way that allows all movements of the robot to be followed. One camera focuses on the top view and the other on the front of the scene.

IV. S OFTWARE A RCHITECTURE In this section, the software components and technologies used are described. Following the Ciclope policy, all the software used is free software with a GPL or compatible license. All the software and documentation developed in this project is also free and can be found in the Ciclope web page [18].

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Fig. 6. Motors, homing switches, and pulse switches for the 4 DOF of the toy robot: turn, depth, height, and grip.

Fig. 7. Students can communicate and exchange ideas in a collaborative way with the chat-blackboard Java applet.

A. Client Side 1) HTML language. 2) Javascript: a programmable API that allows cross platform scripting of events, objects, and actions. 3) Cascading style sheets: mechanism for adding style (e.g., fonts, colors, spacing) to web pages. 4) Java applet: two applets are used: a blackboard chat for communication between users (see Fig. 7), and an ssh terminal in order to access the development PC. B. Server Side The following technologies are installed in the development computer. 1) RTEMS: open-source real-time operating system designed for embedded systems. 2) Apache: the number one HTTP server on the Internet.

3) PHP: a server-side HTML-embedded scripting language. 4) MySQL: very popular database server for building web applications, it is often used in combination with the PHP language. 5) Motion: a program that monitors the video signal from one or more cameras and is able to detect if a significant part of the picture has changed. 6) BOOTPD and TFTP servers: allows the target to receive the program to run. When booting, the target makes a BOOTP request. This is received by the development PC which then sends the executable through the TFTP protocol. 7) Crontab: a tool that allows tasks to be automatically run in the background at regular intervals by the cron daemon. 8) Parapin: a parallel-port pin programming library for GNU/Linux. It is used to control a board which allows resetting, turning the target on/off, and switching the bulb on/off. 9) Libserial-mt: a library that provides a C++ multithreading encapsulation for serial port ioctls. In addition, it provides buffering mechanisms in order to support active rs232 devices. It is used to redirect the RTEMS I/O to the serial port that joins the development PC and the target. C. User Interface The interface of the web application is shown in Fig. 8. The following operations can be carried out. 1) Reset the target. 2) Turn the target on/off. 3) Turn the bulb on/off. 4) Open ssh terminal. 5) Open blackboard chat. 6) Interact with the control program of the robot. 7) Maximize the camera views (full screen). 8) See the remaining reservation time. 9) Rotate platform.

LÓPEZ et al.: CICLOPE ROBOT: WEB-BASED SYSTEM TO REMOTE PROGRAM AN EMBEDDED REAL-TIME SYSTEM

Fig. 8.

Fig. 9.

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User interface where the two different views of the robot and one of the ssh terminal Java applets can be seen.

Hanoi Tower problem.

V. S TUDENT ’ S P RACTICALS The students, in groups of two or three, must solve the wellknown problem of the Hanoi Towers, presented by the French mathematician Édouard Lucas [41]. The problem consists of moving all the pieces from positions 1 to 3, as shown in Fig. 9. There are two rules as follows: 1) The pieces must be moved one by one and 2) a piece can never be placed over another smaller one. The students must design the control of the robot using an Ada or C/POSIX of RTEMS interface. There are no explicit timing requirements; however, the students have to program coordinated movements in order to get the shortest path between two spatial points. All the students work collaboratively and remotely on the same terminal (see Fig. 8). Anybody can edit, compile, or run the program while the other members can look on. In order to execute the program in the target PC, somebody needs to press the on/off button or the reset button on the web interface. As was explained in Section II, the program is loaded from the development PC via TFTP. The chat can be used for discussions between members. Images are sent from the web cameras to the web application to provide feedback from the experiment. If the students want to measure time, position, or other parameters, they need to program it in the control application, since the video is not in real time. Regarding the evaluation, the students must write an explanatory report. After reading it, the teacher makes a remote

appointment with the group. The usual procedure is that teacher and students access the web application, and the students run their program in order to solve the problem of the Hanoi Towers. However, appointments can also be held in the physical laboratory. All the events performed by the group (edition, compilation, execution, shutdowns, reboot, size of the code, connection time, rotating the platform, etc.) are stored in a database. These data can be visualized with bar/pie charts in the web application. This allows teachers to obtain some statistics to measure the degree of collaboration between the different students of the same group and to aid in the evaluation of each member of the group. Fig. 10 shows an example of the statistical graphics for visualizing students’ use of the laboratory.

VI. C ONCLUSION AND F UTURE W ORK We have presented a laboratory for educational purposes for the subject of DDCS, which was originally designed with free software and inexpensive components. This laboratory has been used at the UPM-FI for the last six academic years and as a remote laboratory for two years. Our teaching experience using this educational laboratory has shown that the more dynamic the system, the more it appeals to students, and as a consequence, the more efficient it is pedagogically. A number of features distinguish Ciclope Robot from most other systems. The two most important are the collaborative approach and the use of an open-source and open-content methodology. The first feature facilitates the collaboration among students while doing their laboratory work through tools such as chat, blackboard, etc. Regarding the second one, the main benefit is that any person can replicate, improve, or integrate the web laboratory into a learning web environment. The development of Ciclope Robot is distributed under GPL licenses and freely available to the

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Fig. 10. Interface where teacher can see the time worked by the groups.

entire educational community on the project web site [18]. In this respect, it is worth pointing out the potential for collaboration between teachers in designing new experiments, new software, and content. The authors’ aim with this paper is to offer the education community the possibility to increase the accessibility to educational laboratories by using web technologies, without placing a high demand on resources. It is expected that the number of students will increase dramatically as a result of the opportunity to do practical work from a distance. Moreover, it is expected that this laboratory will be used in other subjects or by other universities, thereby saving resources by reusing this laboratory. Since the initial development of the system, several improvements have been introduced: Adding audio transmission to the application, changing the application to make it accessible according to W3C, and enabling remote debugging. Furthermore, there are plans to integrate it into GATE, the learning web platform of the authors’ university. The next improvements are aimed at solving the problem of dropping the pieces and creating new experiments with the robot and the same web application. R EFERENCES [1] P. Penfield, Jr. and R. C. Larson, “Education via advanced technologies,” IEEE Trans. Educ., vol. 39, no. 3, pp. 436–443, Aug. 1996. [2] R. L. Taylor, D. Heer, and T. S. Fiez, “Using an integrated platform for learning to reinvent engineering education,” IEEE Trans. Educ., vol. 46, no. 4, pp. 409–419, Nov. 2003. [3] P. Joo-Hyun, K. Pang-Ryong, and L. Hong-Woo, “Empirical study on the enhancement of the quality of cyber education,” in Proc. Technol. Manage. Global Future—PICMET, Jul. 2006, vol. 3, pp. 1373–1384. [4] O. Gomis, D. Montesinos, S. Galceran, A. Sumper, and A. Sudrià, “A distance PLC programming course employing a remote laboratory based on a flexible manufacturing cell,” IEEE Trans. Educ., vol. 49, no. 2, pp. 278–284, May 2006. [5] M. J. Callaghan, J. Harkin, T. M. McGinnity, and L. P. Maguire, “Intelligent user support in autonomous remote experimentation environments,” IEEE Trans. Ind. Electron., vol. 55, no. 6, pp. 2355–2367, Jun. 2008.

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Diego López was born in Segovia, Spain, in 1981. He received the M.S. degree in computer engineering from the Universidad Politécnica de Madrid, Madrid, Spain, in 2005, where he is currently working toward the Ph.D. degree in computer vision in the Computer Architecture Department, Computer Engineering School. He is a Technician for the Astrophysics Network of the Autonomous Community of Madrid (ASTROCAM) Project. His research interests include distance learning, teleoperation, and computer vision.

Raquel Cedazo was born in Madrid, Spain, in 1981. She received the M.S. degree in computer engineering from the Universidad Politécnica de Madrid, Madrid, in 2005, where she is currently working toward the Ph.D. degree in computer engineering in the Computer Architecture Department, Computer Engineering School, and where she also received a doctoral fellowship cofinanced by the COLDEX project in 2005. Her research interests include distance learning, collaborative learning, and web technologies.

Francisco Manuel Sánchez (M’01) was born in Madrid, Spain, in 1967. He received the B.S. degree in electrical engineering from the Universidad Pontificia de Comillas, Madrid, in 1989, and the M.S. degree in electronics and control engineering and the Ph.D. degree in computer vision from the Universidad Politécnica de Madrid, Madrid, in 1993 and 2001, respectively. He received a doctoral fellowship from the Spanish Education Ministry in 1995. From 1993 to 1995, he was with Eastman Kodak. From 1995 to 1998, he was with the Control Department, Industrial Engineering School, Universidad Politécnica de Madrid, where since 1998, he has been a Teacher in the Computer Architecture Department, Computer Engineering School. He teaches operating systems, real-time systems, and process control. His research interests include distance learning, teleoperation, and computer vision. Dr. Sanchez is a member of the International Society for Optical Engineers and the International Federation of Automatic Control.

José María Sebastián (M’07) was born in Madrid, Spain, in 1959. He received the B.S. degree in electrical engineering, the M.S. degree in control engineering, and the Ph.D. degree in computer vision from the Universidad Politécnica de Madrid, Madrid, in 1979, 1982, and 1987, respectively. He is currently a Teacher in the Control Department, Industrial Engineering School, Universidad Politécnica de Madrid, where he has been since 1982. He teaches courses in computer vision and control engineering. His research interests include distance learning, teleoperation, and computer vision. Dr. Sebastian is a member of the International Society for Optical Engineers and the International Federation of Automatic Control.