LinuxCNC (Formerly called Enhanced Machine Controller, or EMC2,) is a FLOSS GNU/Linux software system that implements numerical control capability using general purpose computers to control CNC machines. It is developed by a number of volunteer developers at LinuxCNC.Org. Following alleged discussions with the EMC Corporation it has been decided to rename this application LinuxCNC.

Purpose[edit source | editbeta]

LinuxCNC is a software system for numerical control of machines such as milling machines, lathes, plasma cutters, routers, cutting machines, robots, hexapods, etc. It can control up to 9 axes or joints of a CNC machine using G-code (RS-274NGC) as input. It has several GUIs suited to specific kinds of usage (touch screen, interactive development). Currently it is almost exclusively used on x86 PC platforms, but a couple ports to other architectures are in use (Alpha,SPARC^{[citation needed]}). It makes extensive use of a real time-modified kernel, and supports both stepper- and servo-type drives.

History[edit source | editbeta]

The EMC Public Domain software system was originally developed by NIST,as the next step beyond the National Center for Manufacturing Sciences / Air Force sponsored Next Generation Controller Program[NGC 1989] /Specification for an Open Systems Architecture[SOSAS]. It was called the ECA [Enhanced Machine Controller Architecture 1993]. Government sponsored Public Domain software systems for the control of milling machines were among the very first projects developed with the digital computer in the 1950`s. It was to be a "vendor-neutral" reference implementation of the industry standard language for numerical control of machining operations, RS-274D (G-code). The software included the RS274 interpreter driving the motion trajectory planner, real-time motor/actuator drivers and a user interface. It demonstrated the feasibility of an advanced numerical control system using off the shelf PC hardware running FreeBSD^{[citation needed]} or Linux, interfacing to various hardware motion control systems.

The demonstration project was very successful and created a community of users and volunteer contributors. Around June 2000, NIST relocated the source code tosourceforge.net under the Public Domain license in order to allow external contributors to make changes. In 2003, the community rewrote some parts of it, reorganized and simplified other parts, then gave it the new name, EMC2. EMC2 is still being actively developed. Licensing is now under the GNU General Public License.

The adoption of the new name EMC2 was prompted by several major changes. Primarily, a new layer known as HAL (Hardware Abstraction layer) was introduced to interconnect functions easily without altering C code or recompiling. This split trajectory and motion planning from motion hardware, making it much easier^{[dubious – discuss]} to support gantry machines, lathe threading and rigid tapping, and a variety of other adaptations. HAL comes with some interactive tools to examine signals and connect and remove links. It also includes a virtual oscilloscope to examine signals in real time. Another change with EMC2 is Classic Ladder, (an open-source ladder logic implementation) adapted for the real time environment to configure complex auxiliary devices like automatic tool changers.

Platforms[edit source | editbeta]

Due to the need of fine grained, precise real time control of machines in motion, EMC requires a platform with real-time computing capabilities. It uses Linux kernel with real time extensions (RTAI). Installing EMC2 (and the underlying real time extension) is a daunting task, therefore prebuilt binary packages have been built and are being distributed. The policy for EMC2 is to build packages and offer support on Ubuntu LTS (long-term support) releases.^[1]

Design[edit source | editbeta]

LinuxCNC "employs a trapezoidal velocity profile generator."^[2]

Configuration[edit source | editbeta]

LinuxCNC uses a software layer called HAL (Hardware Abstraction Layer).^[3]

HAL allows a multitude of configurations to be built ^[4] while being flexible: one can mix & match various hardware control boards, output control signals through the parallel port or serial port - while driving stepper or servo motors, solenoids and other actuators.

LinuxCNC also includes a software programmable logic controller (PLC) which is usually used in extensive configurations (e.g. complex machining centers). The software PLC is based on the opensource project Classicladder,^[5] and runs within the real-time environment.

References[edit source | editbeta]

Notes

Bibliography

• Proctor, F. M., and Michaloski, J., "Enhanced Machine Controller Architecture Overview," NIST Internal Report 5331, December 1993. Available online atftp://129.6.13.104/pub/NISTIR_5331.pdf
• Albus, J.S., Lumia, R., “The Enhanced Machine Controller (EMC): An Open Architecture Controller for Machine Tools,” Journal of Manufacturing Review, Vol. 7, No. 3, pp. 278–280, September 1994.
• Lumia, "The Enhanced Machine Controller Architecture", 5th International Symposium on Robotics and Manufacturing, Maui, HI, August 14–18, 1994,http://www.nist.gov/customcf/get_pdf.cfm?pub_id=820483
• Fred Proctor et al., "Simulation and Implementation of an Open Architecture Controller", Simulation, and Control Technologies for Manufacturing, Volume 2596, Proceedings of the SPIE, October 1995, http://www.isd.mel.nist.gov/documents/proctor/sim/sim.html
• Fred Proctor, John Michaloski, Will Shackleford, and Sandor Szabo, "Validation of Standard Interfaces for Machine Control", Intelligent Automation and Soft Computing: Trends in Research, Development, and Applications, Volume 2, TSI Press, Albuquerque, NM, 1996,http://www.isd.mel.nist.gov/documents/proctor/isram96/isram96.html
• Shackleford and Proctor, "Use of open source distribution for a Machine tool Controller", Sensors and controls for intelligent manufacturing. Conference, Boston MA, 2001, vol. 4191, pp. 19–30, http://www.isd.mel.nist.gov/documents/shackleford/4191_05.pdf or http://dx.doi.org/10.1117/12.417244
• Morar et al., "ON THE POSSIBILITY OF IMPROVING THE WIND GENERATORS", International Conference on Economic Engineering and Manufacturing Systems, Brasov, 25–26 October 2007, http://www.recentonline.ro/021/Morar_L_01a.pdf
• Zhang et al., "Development of EMC2 CNC Based on Qt", Manufacturing Technology & Machine Tool, 2008, http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZJYC200802046.htm
• Leto et al., "CAD/CAM INTEGRATION FOR NURBS PATH INTERPOLATION ON PC BASED REAL-TIME NUMERICAL CONTROL", 8th INTERNATIONAL CONFERENCE ON ADVANCED MANUFACTURING SYSTEMS AND TECHNOLOGY JUNE 12-13, 2008 UNIVERSITY OF UDINE - ITALY, http://158.110.28.100/amst08/papers/art837759.pdf
• Xu et al., "Mechanism and Application of HAL in the EMC2", Modern Manufacturing Technology and Equipment 2009-05, http://en.cnki.com.cn/Article_en/CJFDTOTAL-SDJI200905037.htm
• Zivanovic et al., "Methodology for Configuring Desktop 3-axis Parallel Kinematic Machine", FME Transactions (2009) 37, 107-115,
• Glavonjic et al., "Desktop 3-axis parallel kinematic milling machine", The International Journal of Advanced Manufacturing Technology Volume 46, Numbers 1-4, 51-60 (2009), http://dx.doi.org/10.1007/s00170-009-2070-3
• Staroveski et al., "IMPLEMENTATION OF A LINUX-BASED CNC OPEN CONTROL SYSTEM", 12th INTERNATIONAL SCIENTIFIC CONFERENCE ON PRODUCTION ENGINEERING –CIM2009, Croatian Association of Production Engineering, Zagreb 2009,
• Li et al., "Control system design and simulation of parallel kinematic machine based on EMC2", Machinery Design & Manufacture 2010-08,http://en.cnki.com.cn/Article_en/CJFDTOTAL-JSYZ201008074.htm
• Li et al., "Kinematics Analysis and Control System Design of 6-DOF Parallel Kinematic Machine with Matlab and EMC2", Advanced Materials Research (Volumes 102 - 104): Digital Design and Manufacturing Technology, 2010, http://dx.doi.org/10.4028/www.scientific.net/AMR.102-104.363
• Klancnik et al., "Computer-Based Workpiece Detection on CNC Milling Machine Tools Using Optical Camera and Neural Networks", Advances in Production Engineering & Management 5 (2010) 1, 59-68, http://maja.uni-mb.si/files/apem/APEM5-1-view.pdf
• Milutinovic et al., "Reconfigurable robotic machining system controlled and programmed in a machine tool manner", The International Journal of Advanced Manufacturing Technology, 2010, http://dx.doi.org/10.1007/s00170-010-2888-8

External links[edit source | editbeta]

• EMC2 project homepage at www.linuxcnc.org
• EMC2 project wiki
• The NIST RS274NGC Standard - Version 3 Aug 2000 also available as a PDF
• The Enhanced Machine Controller homepage at NIST