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REMOTE CONTROL OF INDUSTRIAL PROCESSES R. Neto, João Alves, Jorge Alves, A. Carvalho I. Fonseca, N. Miguel, E. Emílio, H. Fachada*
Institute of Engineering of Coimbra, Dept. of Electrical Engineering, Quinta da Nora, 3031-601 Coimbra Codex, Portugal, Tel: 351 239790200, fax: 351 239790220, e-mail:
[email protected],
[email protected],
[email protected],
[email protected]*
Abstract: This work consists in a general system with remote supervision for control of industrial processes. The main goal of this system is to improve the performance of industrial automatic processes. This method uses up to date information technology where the communications plays a fundamental role contributing to establish relationships and saving up time. The present work was tested in an electric-pneumatic system for quality control supervised by a personal computer which analysis quality of the scheduling performance. The control quality program sends periodical reports to a web page and allows a telnet access and a telephone service. This system that we call Petra’s can be visualized remotely in real time, too. Copyright 2000 IFAC
Keywords: TeleControl, WebControl, Voice Servers, Industrial Process, Automate..
1. INTRODUCTION
they bring people nearly, they provide contacts and save up time.
In the last years of the XX century, the man has lived as a function of the time , in particular, he has tried to fulfill a greater variety of tasks in a shorter range of time. This situation has led to additional difficulties, in particular, the need to be in touch with a lot of persons / organizations, to be well informed about the plant production for which he his responsible; this can be called, the globalization phenomena. (Hirzinger, 1995)
This research project leads with networking, exploring the ability of the remote control of industrial processes by means of communications channels such as the telephone, http (hypertext transfer protocol), Telnet, DDE (Dynamic Data Exchange) and RPC (Remote Procedure Call) see (Alberto, 1999; Álvares, A. J. & Romariz 1998) and A. Brooks 1997).
Taking into account this scenario the communications plays a fundamental role, since
In this work we have used a personal computer (PC) with a modem and an ethernet card, an automate CPM 1 (Omron) and a machine which
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represents a quality control system (Petra) for a production line. This procedure can be supervised by the communication system
referred above (J. Bonnet, 1999). The PC can also control the room light, as well as, the temperature and the indoor air ventilation
GSM
WWW
Building Supervisor e-mail
CPM1
Petra
Fig. 1: Monitoring system.
In this work we have used a personal computer (PC) with a modem and an ethernet card, an automate CPM 1 (Omron) and a machine which represents a quality control system (Petra) for a production line. This procedure can be supervised by the communication system referred above. The PC can also control the room light, as well as, the temperature and the indoor air ventilation. The developed program allows the execution of different tasks, such as: to send reports by electronic mail (e-mail) / fax / telephone / telnet; the visualization of the state of the machine, by a video camera, which images are on-line in a WWW server (http://projele.isec.pt/~petra); a voice server that checks the system by telephone; a remote control of the machine by http / telnet.
2. IMPLEMENTATION The system (Fig. 1) is programmed in the supervisor computer (PC). A programmable automate (CPM 1) controls the operation of the machine (Petra). It has been made a small factory model to simulate the room temperature control, as well as, air flow and luminosity control. The supervising task was carried out with C++ Builder 3.0. The Petra's control program (Fig. 2) was done on a Omron (CPM 1) automate programmed in Ladder on a Syswin 3.1 environment, also from Omron. A DS5000 (Dallas Semiconductor) microcontroller realizes the control of the indoor air conditioning, temperature and light control (Fig. 3). It was programmed in C51 (Keil-µVision51 ver. 1.24) and communicates with the supervisor over a RS232 link. The production control system (Fig. 3), allows the selection of a few kind of pieces taking into account their thickness and hole positions. This control task uses some pneumatic and electric
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actuators and a few sensors to determine the state of the machine. Automatic part selection is
allowed,
as
well
as,
manual
control
Fig. 2: Petra’s Supervising Software via www, mail, gsm.
Fig. 3: The Petra system (right) is controlled by CPM1. The building maquete (left) is monitored by the DS5000 3. DESCRIPTION OF THE REMOTE COMMUNICATION CHANNELS
periodically, over the following channels: -
3.1 Voice server For the elaboration of the phone receive system, we created a module of speech synthesizer voice witch allows to give spoken messages for the user options received by DTMF (Fig. 4). 3.2 Periodically reports The supervising program of the Petra machine allows the statistical information to be sent,
by telephone or fax (the phone/fax number can be programmed). by electronic mail (the address and the SMPT server can be programmed).
3.3 Telephone server The available telephone service makes possible the remote control and information exchange through a normal phone line. To get access to this service, the user needs to make a call to the supervisor phone number and introduce a code
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pin only. The code and options are understood by DTMF codes (input) and through a voice synthesis process (output). The main menu has two options (Fig. 5): 1) LISTEN. This option gives access to the statistical information and to
2)
the total amount of produced pieces. CONTROL. This option is reserved for special use ("Super User") allowing total control of the Petra system.
Fig. 4: Configuration of the e-mail address witch receives the periodically reports.
Fig. 5: Flow of the telephone service input by DTMF tones after "Super user" validation pin.
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3.4 Video system
The remote access computer can visualize the state of the machine Petra and its environment using a browser http. The video camera is attached to the computer where is the Petra supervising software. The captured images are sent, periodically, as a standard image file, to the page Petra Online on a ftp server (Fig. 6).
3.5 Telnet server This server is resident in the supervising computer. It can be remotely accessed by any one who knows the IP address of this computer and has permission to use this access. A password is asked after login, for system security.
Fig 6 – Captured image of Petra’s system.
There are two modes of access, as user or as an administrator , depending on the login and password. It is allowed simultaneous users access. The user can only access statistical information while the administrator can use all the information available and completely control the machine. The Telnet server manages the periodical actualization of the HTML page with statistical information and the visualization of the state of the machine through a CGI created for this purpose.
From the telnet access, this server allows the following commands, as we see in Fig. 7: -
help, informs about every command; petra / start, puts the system ON; petra / stop, stops the system; petra / reset, initializes total count; petra / option [argument], selects (from 1 to 7) the qualified part to be counted; report, shows the report of total controlled parts till this moment;
Example: petra / option 2 "It means to select the un-holed part for counting"
Fig. 7 – Telnet client session of Petra’s system.
3.6 Communications between the server and used equipment The communications between the PC and every supervised equipment is done through a RS-232 link (or others like RS-485 or Ethernet). This link allows the data exchange in message format according to CPM1 format and DS5000 programmable format. The supervising software is easily adapted for other industrial distributed networks, with known message protocol.
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4. CONCLUSIONS The present work shows clearly the main advantages of the remote access to supervise industrial control systems. This make possible the production situation to be known, changed or programmed on-line without physical presence of supervising people. Also, it is possible to analyze the production sate trough the automatic reports. In the industrial world, there is a large interest in the electronic business, electronic control and remote process supervising. So it is important to bring into the industrial world, technologies like supervision software with most of the generic communication interfaces, WebPLC - Internet-based PLCs, using TCP/IP and Ethernet Networks as standard communication protocols, that allows applications such as WebBrowsers to control machines anywhere. The availability of the internet software allows with a minimal effort of programming the remote access of industrial automated system with the methodology presented. This Internet technology can be used to break the barrier of proprietary communication systems, bringing the power of open systems to the industrial world.
REFERENCES Alberto and J. Alves, (1999). Telerobótica: Metodologia para o Desenvolvimento de Sistemas Robóticos Teleoperados via Internet. XV Congresso Brasileiro de Engenharia Mecânica. Álvares A. and J. & Romariz, L. J. (1998). Desenvolvimento de um manipulador com dois graus de liberdade controlado remotamente via internet. V Congresso de Engenharia Mecânica Norte e Nordeste, Fortaleza. Brooks A. and G. Dickins, A. Zelinsky, J. Kieffer and S. Abdallah, (1997). A High-Performance Camera Platform For Real-Time Active Vision. Proceedings of the First International Conference on Field and Service Robotics. Bonnet J. and E. Gnaedinger, F. Lepage, (1999). “Proposition d’un modèle d’architecture de communication pour des applications industrielles distribuées et multimedia. 3rd International Conference on Industrial Automation. Taylor, K. and Trevelyan, J. (1995). Telerobot on World Wide Web. National Conference of the Australian Robot Association, Melbourne. Hirzinger, G.. (1997). Teleoperating space robotsimpact for the design of industrial robots ”. 12-16, pp 250-256 IEEE International Symposium on Industrial Electronics, Portugal. Zheng , J. Y. and Zheng Q. Chen S. Tsuji, (1991) “Active camera guided manipulation'” In Proc. of 1991 IEEE Int Conference of Robotics and Automation.
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