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ERNESTO LO VALVO

A Web based remote control of CNC machines

  • Autori: Licari, R.; LO VALVO, E.; Piacentini, M.
  • Anno di pubblicazione: 2009
  • Tipologia: Proceedings (TIPOLOGIA NON ATTIVA)
  • Parole Chiave: CNC, Open Source, EMC, remote control
  • OA Link: http://hdl.handle.net/10447/42673

Abstract

Due to the large variety of products in small batch sizes, a modern machining shop floor requires an advanced real-time control system able to both monitor all the features and adapt the manufacturing system to the rapid changes of production capability and functionality. This is especially true when the shop floors are combined with the e-Manufacturing concept. e-Manufacturing is a transformation system which enables the manufacturing operations to achieve a predictive near-zero-downtime performance as well as to synchronize with the management systems through the use of infotronics technologies (i.e., wireless connections, web applications, networking systems, etc.). In recent years, the impact of web-oriented technologies has added “velocity” to the design, manufacturing, and aftermarket service of a product. Today’s competition in manufacturing industry depends not only on lean manufacturing but also on the ability to provide customers with total solution and life-cycle costs for sustainable value. Companies are always under a high pressure to improve their efficiency in terms of product development, operations, and resource utilization with a transparent visibility of production and quality control. However, a highly efficient infrastructure, able to integrate all the parts of an automated equipment together and to link them to the e-Manufacturing, is still not available. The objective of this research is to develop an appropriate methodology with open architecture for real-time monitoring and remote control of some networked CNC machines. A new enabling technology is therefore urgently required in order to bring traditional CNC machine tools on-line with combined monitoring and control capability. Without it, the advanced factory automation will hardly have the possibility to become practical in the next generation distributed manufacturing shop floor environments. Thanks to the availability of low cost and Open Source CNC systems, it is currently possible to use CNC technology even in very simple and small production environment. The milestone of this research is EMC2, a Linux CNC-executable control program, freely downloadable on the Internet, able to control servo-motors, stepper motors, robots and other automated devices. It allows CNC machine users to manage a numerical control machine from the parallel port of an even low-performing PC. It provides motion planning with cutter radius compensation, tool length offsets, and constant velocity control. It also have support for non-Cartesian motion systems. This includes hexapods (Stewart platforms and similar concepts) and systems with rotary joints to provide motion. In order to remotely manage a EMC2 based CNC machine, a computer remote control of a milling station has been realised in two different configurations: thanks to a webcam pointed on the working table, the remote computer shows the milling machine movements. The first configuration uses an SSH client and server - indeed it is possible to install them not only on a great number of such UNIX versions as Linux and Mac OS X, but also on Windows. The second one uses a remote text shell (like telnet) and three different methods to broadcast images. The structure is based on a server running Linux (Ubuntu 8.04) on which EMC2 is installed. Thanks to a TCP/IP network, the server connects many CNC machines; moreover users are able to connect their computer to the server and to control CNC machines by using a wireless LAN. Some tests have been performed by using different computers (also a brand new netbook) in order to verify the real efficiency of the structure. The remote programs can be seen on separated windows: this way users are able to open multiple windows at the same time, one with EMC2 and the other with the webcam image visualisation program. In this aim, a suitable software which is able to send images to a server by