CONCEPT FOR ONLINE WEB MACHINE TOOL CONTROL BASED ON OPEN SOURCE

8th International DAAAM Baltic Conference "INDUSTRIAL ENGINEERING 19-21 April 2012, Tallinn, Estonia CONCEPT FOR ONLINE WEB MACHINE TOOL CONTROL BASED ON OPEN SOURCE Radelja, H., Hasković, D., Šikulec, L., Plančak, M., Kršulja, M. & Car, Z. Abstract: The direction for the future development of the production process is complete autonomy, artificial intelligence, ability to diagnose errors, self-repair and, most importantly, to minimize impact of human factors. Although technology is not yet mature enough for a complete exclusion of worker from the machining process remote control could enable unmanned operation. The concept offered in this study consists of building a custom WEB application for machine tool control that provides flexibility, operation from any remote location, ensures platform independence and low cost due to use of Open Source Architecture. Key words: remote control, WEB control, CNC machine tool, WEB-based manufacturing, Open Source 1. INTRODUCTION There have been a number of key changes through the development of machine tools, which have, each for themselves, improved and simplified their use. In particular, one can emphasize the development of the CNC control that proved to be more productive, easier to use, enabled production of more complicated workpieces and made the technology accessible to a wider number of users. Any improvement also means higher productivity, accuracy, efficiency and ultimately, higher profits in manufacturing. One of the prospects of development that are discussed today is the remote control. This type of control is particularly interesting because, thanks to automated systems that regulate all the parameters of processing, the operator no longer has to be close to the machine tool while operating. From the viewpoint of production economy, if the employee does not have to be by the machine, but instead it can monitor it while on another job, this presents a benefit because worker can perform several tasks at the same time, he can do some other work or monitor several machines simultaneously. Remote control enables not only monitoring but to completely control the process - in case of error, processing can be stopped, check what caused the error, possibly change the parameter and continue processing. A number of researches are conducted on remotely controlling the machine tools, with different approaches and solutions for different aspects of the problem [ 1 ]. In most cases, it was just a simulation and monitoring processing without the possibility of operating in real time. One part of the research is focused on supporting the design and planning process over the Web, such as CyberCut [ 2 ], Internet Manufacturing [ 3 ], which offer solutions for overcoming the problem of physical distance from the R&D teams and technology planning process and offer practical platform for concurrent engineering. One popular approach to implement remote control is to establish a client - server communication, either by developing their own applications or by using commercial software [4] such as VNC or pcanywhere, which allows taking control over the system that controls the machine tools

from a remote location. The advantages of this solution are ease of implementation, the use of existing infrastructure, but there are major drawbacks in terms of flexibility, providing real-time control and safety in case of a disconnection. The solution offered in this study consists of building a custom Web application for machine tool control that provides flexibility, scalability, operation from any remote location, and ensures platform independence and low cost due to use of Open Source Architecture. 2. TELECONTROL Telecontrol is defined as a continuous and direct control of the remote machine [5]. Advantages of telecontrol are already identified and widely present in everyday life, mostly for the purpose of improving the quality of human life. Whether it is the TV remote control device, smart house, a remote support for a service or a product, control of the plant or the remote control of robots that perform hazardous tasks. The application of telecontrol for the machine tools operation opens up new possibilities to extend the usability and commercialization of a machine. It enables virtual business between geographically distant subjects [ 6 ] through the formation of partnerships and utilization of external resources without the necessity of purchasing the equipment. Allows manufacturers to locate production facilities closer to the customer or the less costly location while highly skilled workers who operate the equipment can be located closer to the R & D department and the administration for better communication and centralization of human resources. It also enables cost reduction because it opens up the possibility of working from home, the parallel execution of some other work or operating multiple machines simultaneously. Therefore, it is not surprising that one of the better-known manufacturers of machining equipment, OKUMA, for a series of products THINC -OSP Constant Care [ 7 ] offers, free of charge, support that includes remote monitoring and control of devices for diagnostic and service. There are many web-based collaboration systems [ 8 ], mainly for: simultaneous design, Web-based RP, project management, Conflict Resolution during collaboration. Rare for: Monitoring workshop machining - Job Shop, remote-controlled CNC machining, advanced automation facilities, which are typically limited in functionality, used for monitoring or offline simulation. That the machine manufacturers noted the need to develop telecontrol is indicated by the fact that most modern equipment has the ability to connect to the Internet, while only ten years before that option had only about 10 % of CNC machines [ 9 ]. 2.1 Control method selection One of the most important criteria when choosing a method of control is of a financial nature. The goal is to develop a system based on open source, free programs and infrastructure that is flexible, cost-effective but with relatively limited capabilities, or a system with far more advanced functions and capabilities, ready to use "out of the box", for which however, is necessary to provide significant financial resources. The choice will depend on the characteristics of the problem to be solved and of the assessment which method is the most affordable, most reliable, most widespread and most cost-effective. This concept is based on open source infrastructure, with the intention of researching its capabilities, bearing in mind the comparative advantages of flexibility and platform independence. There is a large choice of means of communication, the use of the GSM mobile network, local wired and wireless

networks, Bluetooth technology, infrared, radio frequency and others. For the purposes of remote control internet imposes as the most suitable, since it is most widespread and enables global connectivity. The Enhanced Machine Controller (EMC2) is selected for the control unit of the machine tool, the Open Source CNC controller, based on the RS-274 standard programming language. Its functions are available externally and can be easily implemented in a web application. The control unit was developed as part of the Ubuntu linux distribution, so it is convenient to choose that operating system for machine tool control. Exclusively free open source applications were used. Apache server and SQL database, and for programming the Web application HTML, Java, PHP, and socket programming. 2.2 The security and robustness issues The first aspect of network security is data loss and the delivery order of the information packages, which is solved using the TCP protocol. When working with data exchange and remote control there is always the possibility of compromised security, meaning unauthorized access to the data or changing the control instructions causing damage to the computer and equipment. This can be extremely dangerous, because if the system is compromised not only that the machining process can cause material damage, but since it handles sharp tools and fast moving parts it may cause serious injury. Intrusions can be deliberate, but also they can be accidental connections to an unsecured network. Therefore, it is of utmost importance to adequately protect used network. For wireless networks protection various systems of data encryption are implemented. In addition, there is a risk of malicious software such as worms, viruses, trojans or spyware. Various antivirus programs are designed to help prevent system infection and suppress possible damage caused by malicious software. 3. REMOTE CONTROL CONCEPT Today the most popular and most common way of communicating is the internet. It allows users to search, browse, retrieve, disseminate and share information remotely. It truly provides global connectivity and the ability to easily remotely control from any point on Earth [ 10 ]. The foundation of the concept of Web telecontrol is based on simplicity and low cost of development and deployment. Fig. 1 shows a diagram of the developed concept of web control [ 11 ]. The concept consists of the developed Web application that is accessed from the computer that is connected to the internet via a TCP/IP protocol. Real time communication with the server is provided using socket programming. Server forwards requests to the EMC2 control unit [ 12 ] that is physically connected to the machine tool. The application of open source provides the flexibility. Since the control unit s functions are available externally for implementation in a Web application, it is possible to directly control the control unit instead of taking the control over the computer on which the control unit is installed.

Fig. 1. Schematic representation of WEB control of machine tool 3.1 EMC2 control unit EMC2 is a CNC control unit. It is a free programming solution, which is based on free source code. It is suitable to operate machine tools, machine tools, robots and other automated devices. It can control servo or stepper motors, relays and other devices related to machine tools. The system of stepper engine controlled from Linux PC, which is connected to them through the parallel port, is shown in Fig. 2. These signals are sent to the actuators that drive the engines. It is also possible to control servomotors via interface card or using parallel connectors that are associated with external control units. Script sets the server on port 10000, and after that communication with server is possible. In this way, the Linux computer is configured to expect external commands, but still remains to define how to establish a link between the website and server set. 3.2 Linking web pages to the server To make a web page able to communicate with the server over the Internet, it must be written in a special programming language; in this case, PHP language was selected. This enables it to send commands in the form of packets of information across an imaginary'' pipeline'' to server which forwards them to the EMC2 program, and it manages machine. This method of programming data exchange is called socket programming and provides realtime communication between clients and servers. Secured communications, it is necessary to define the function and appearance of Web applications for machine tool control. Fig. 2. Scheme of EMC2 control of the 3-axis stepper drive system [ 12 ]

Fig. 3. Web application for machine tool control To enable the automatic update of web pages Java Script or JavaScript Timing Events function have been used. With this function, it is possible to perform a set of instructions in the specified time interval. In this case, command is sent, which gives feedback about position. Update interval is one second. Due to the physical distance of the user from the machine tool, it is necessary to provide some form of monitoring of machining processes. The best feedback is visual information. For this reason, a web site is capturing live images from Web cameras located near the machine tool pointing towards the workpiece. With the change of certain parameters, it is possible to change the resolution and image size, number of frames per second and the IP address of the computer on which webcam server is mounted. The video image is not possible because relationship with a webcam server should be re-established for every update. For that reason, part of page should be separated from static part in separate frame, which allows viewing HTML document inside another HTML document or Web pages within a frame containing another website. In this case, the static part of the site refers to frames for video display and control buttons, while the coordinates are display is in a separate frame that allows updates. 4. CONCLUSION The concept of Open Source remote control has been successfully implemented in the example of educational 3-axis milling machine located at the Faculty of Engineering Rijeka, and which can be controlled via the Internet. For demonstration purposes, only basic functions are programmed. On / off machine switch, starting, pausing and stopping the loaded program. This Web application can be easily extended to perform all the functions of the control

unit. Remote control of the machine tool through the web is opening the possibility for online collaboration and renting a machine, therefore one of the directions in which to carry out further research system management tasks and coordination of multiple users, and, ideally, to ensure 24 hour availability of the machine, automatic supply of raw materials and removal of workpieces. For the purposes of online production, it is necessary to develop a virtual model of the machine tool, with the ability to simulate the production process using a remote control. This way user would be able to detect possible faults in selected strategies, cutting data values [ 13 ] and to train users, to avoid possible errors that could result in damage to the workpiece or machine. 5. ACKNOWLEDGEMENTS The authors would like to acknowledge the support provided by the National CEEPUS Office of Croatia and National CEEPUS Office Serbia, which helped the research through mobility in the frame of the CEEPUS II HR 0108 project. 6. REFERENCES 1. Lala, S. P., Onwubolu, G.C.: Three tiered web-based manufacturing system Part 1: System development, Robotics and Comp.-Integrated Man. 23 (2007) 138 151. 2. Ahn, S. H., Sundararajan, V., Smith, Charles, et. al.: CyberCut: An Internetbased CAD/CAM System ASME Jour. of Comp. and Inf. Sci. in Eng., Vol.1, 1, 2001. 3. Tay, F. E. H., Khanal, Y.P., et.al: Distributed rapid prototyping a framework for Internet prototyping and manufacturing. Integrated Manuf Syst 2001;12 (6):409 15. 4. Lee, R.S., Tsai, J. P., Lee, J. N., et.al: Collaborative virtual cutting verification and remote robot machining through the Internet. Proc Inst Mech Eng 2000; 214B:635 44. 5. Angheluta, L., Moldovan, A., Radvan, R.: The Teleoperation of a Lif Scanning Device U. P. B. Sci. Bull., Series A, Vol. 73, Issue. 4, 2011. 6. Lan, H., Ding, Y., Hong, J., et.al: A webbased manufacturing service system for rapid product development Computers in Industry 54 (2004) 51 67. 7. Felix, C.; Advantages of Remote Troubleshooting Production Machining Magazine, Gardner Publications, Ohio 2011-10-2. 8. Wang, L., Orban, P., Cunningham, A., Lang, S.: Remote real-time CNC machining for web-based manufacturing Robotics and Computer-Integrated Manufacturing 20 (2004) 563 571. 9. Waurzyniak, P.: Electronic Intelligence in Manufacturing, Manufacturing Engineering, Vol. (3), 2001, pp. 44-67. 10. He, H., Wu, Y.: Web-based virtual operating of CNC milling machine tools Computers in Industry 60 (2009) 686 697. 11. Hasković, D.; B. Sc. Thesis, University of Rijeka, Faculty of Engineering, 2009. 12. The EMC Team : EMC Handbook, LinuxCNC.org, 2011. http://linuxcnc.org Accessed on: 2011-11-05. 13. Car, Z., Barišić, B., Ikonić, M.: GA Based CNC Turning Center Exploitation Process Parameters Optimization Metalurgija. 48 (2009), 1; 47-50. 7. ADDITIONAL DATA ABOUT AUTHORS Assistant Hrvoje Radelja, PhD student, Damir Hasković, MSc, Assistant Leon Šikulec, PhD student, Assistant Marko Kršulja PhD student and Prof. Car Zlatan,PhD, Vice Dean for business affairs. Faculty of Engineering, Vukovarska 58, 51000 Rijeka Croatia E-mail: car@riteh.hr Prof. Miroslav Plančak, PhD, Faculty of Technical Sciences, Trg Dositeja Obradovića 6, Novi Sad, Serbia. E-mail: plancak@uns.ac.rs