New_CNC
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
INC: A NEW PHILOSOPHY OF CNC
TAN LIU 1, TAO YU 1, SHU-ZHEN YANG 2, WEN-BIN WANG 1
1 CIMS & Robot Center, Shanghai University, Shanghai, 200072, PR China
2 Electromechanical Engineering Institute, Shanghai Second Polytechnic University, Shanghai, 200072, PR China E-MAIL: alanltnew130@https://www.sodocs.net/doc/3c13606692.html,, tyu@https://www.sodocs.net/doc/3c13606692.html,, szyang@https://www.sodocs.net/doc/3c13606692.html,, wenbin_wang@https://www.sodocs.net/doc/3c13606692.html,
Abstract:
This paper proposes a new philosophy of CNC
(Computer Numerical Control), which is named as INC
(Integrated Numerical Control or Intelligent Numerical
Control). First it has a brief introduction of INC and makes a
comparison and analysis about INC, ONC and DNC. Further
it describes the important characteristics of INC and
introduces the key technologies of INC. And then it
emphasizes on discussing some intelligent characteristics of
INC, which includes image recognition and vector
quantization (VQ), intelligent process planning, simulation, etc.
It discusses the principle and application of them in details.
Finally, a case is given to illustrate how to realize INC in the
engineering area.
Keywords:
INC; CNC; Intelligent; Integrated
1. Introduction
It is a long history since CIM (Computer Integrated
Manufacturing) was put forward. The goal of CIM is to
integrate and coordinate, via computer hardware and
software, all aspects of design, manufacturing and related functions. CIM is conceived to be the management
technology that makes feasible the fully-automated factory-of-the-future.
Certain computer-based technologies falling with the broad realm of CIM have been sufficiently well developed. These include computer-aided design (CAD), computer-aided process planning (CAPP), computer-aided manufacturing (CAM), material requirement planning (MRP), manufacturing resources planning (MRP II), capacity requirements planning (CPR) and shop-floor control (SFC). And the topic of networks (telecommunications between computerized elements) pervades many of the specific technologies listed above [1]. But CIMS (Computer Integrated Manufacturing System) is a very large engineering. Only some big enterprises have the conditions to put a complete CIMS into practice. And it involves all aspects of technologies of management, market, planning, computer science, network, cybernetics and so on that makes it is very difficult or almost impossible to be implemented in a great many of small companies. In fact, there are many CAD, CAPP or CAM “isolated island” in small factories, they can not be integrated and coordinated effectively. So INC emerges as the times require. What is INC? It can be seen as a cost-effective integrated theory oriented to manufacturing. And since there is also a concept of DNC (Direct Numerical Control or Distributed Numerical Control), why did we propose such a new INC philosophy? What are the differences among INC, ONC (Open Numerical Control) and DNC? In this paper, a brief introduction of INC is presented first, and then we emphasizes on discussing the difference among INC, ONC and DNC. Second we introduce the architecture and three key technologies of INC. We further discuss some important intelligent characteristics of INC. We also give a case to illustrate how to apply INC in engineering area. Finally, predictions are made on what INC might to be in future years.
2. The philosophy of INC 2.1. Definition of INC INC, proposed by Manufacturing Grid Resource Group of CIMS & Robot Center of Shanghai University, in a narrow sense is the abbreviation of Integrated Numerical Control. It means that abstracting some functions of traditional CIMS, such as CAD, CAPP, CAM, into a series of modules, which makes the application be divided into a group of tasks frame. The tasks frames could be decomposed into detailed sub-functions. Every function module is a practical module oriented to manufacturing, such as code explaining, interpolation and PLC control. The function modules are organized and integrated into the bigger parts modules with the tasks frame. And these parts modules are integrated into a concrete application CNC system finally with a unified user interface. The 0-7803-9091-1/05/$20.00 ?2005 IEEE
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
architecture frame is shown in figure 1.
Figure 1. The architecture frame of INC But different with some general CAD/CAPP/CAM integrated system, the focus of INC is the CNC module. Every foregoing module is the preparation of the CNC module. The other modules all work for the kernel module - CNC module. For example, CAD parts module, which is oriented to CNC module, is not same as the general CAD system. It excludes some advanced and complex functions of computer aided design, such as three-dimensional design and three-dimensional modeling, but includes some useful functions oriented to CNC, such as distilling of image outline, image vector quantization (VQ), image binarization and so on. In a broad sense, INC is the abbreviation of Intelligent Numerical Control. It not only has the functions of INC in a narrow sense, but also has the function of collecting system information, monitoring system conditions to do self-adapting adjustment, recording historical information to analyse and synthetize, making decision, enlarging it own expert database, etc. It has extra expert system and information collecting system than INC in a narrow sense. It also has the function of remote control. 2.2. Difference among INC, ONC and DNC
There is a rich literature in NC area. From the original NC concept to latter-day ONC and DNC, there has been a long research history in that area. Then we make a comparison among them as follows:
ONC is the abbreviation of Open Numerical Control, which is similar to OAC (Open Architecture Control). When NC is developed to be used in the distributed controlling and FMS (Flexible Manufacture System)
environment, further it needs to communicate with
CAD/CAPP/CAM system, the original NC oriented to a
single machine was being found insufficient to satisfy the
new requirements. It was necessary that NC should be
transferred to have an open architecture [3]. Open means
NC has a unified external standard controller interface,
which comprises an extensible man-machine interface,
standard drive interfaces and so on. There are three
authoritative open architecture controller standard
specifications in the world: OMAC (Open Modular
Architecture Controller), OSEC (Open System
Environment for Controller) and OSACA (Open System
Architecture for control within Automation). Compared to
the traditional CNC, ONC is open [4].
DNC is the abbreviation of Direct Numerical control.
In a wide sense, it means Distributed Numerical Control.
DNC was conceived originally as a means of cost-effective program storage and machine control [5]. Therefore the system must be integrated with part programming so that programs can be directly transferred between the storage medium and the machine. DNC use a central computer to hold numerous component programs, and when required these are fed to individual machine tool controllers along a real-time two-way communications network. One DNC central computer can service a variety of dissimilar machine, and if the facility is arranged in cellular form it can store data on production needs, tool wear and machined down-time. This information can be used by management for improved decision making. It integrates communication, control, plan and management together, maybe includes CAD, CAPP and CAM. From above, we can see the differences between INC and DNC. DNC integrates communication, control, plan and management together, maybe includes CAD, CAPP and CAM in some degree. But it aims at controlling a group of NC machines effectively, or further controlling a whole factory. It can be seen as a kind of Distributed Manufacturing. Instead, the heart of INC is CNC. It aims at manufacturing. All its work is for its last task: CNC manufacturing. Its CAD parts module and its CAPP module,
which are oriented to CNC module, are not same as the
general CAD system. It has a good CSCW (Computer Supported Collaborative Work) performance and can be
seen as a good application case of parallel engineering. Contrasted to Distributed Manufacturing, it is a kind of Collaborative Manufacturing [6]. And it is a more
cost-effective approach to realize CIMS than DNC. Theoretically, it can realize CAD/CAPP/CAM in a CNC machine. INC also absorbed the open attribute of ONC. It is integrated and is open as ONC in the same time.
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
3. Important issues of INC
3.1. I
mplementation flow chart of INC
Figure 2. Flow chart of INC
From the following chart (Figure 2), we can see the working process of INC clearly. The whole system is built on the base of engineering database. The database is constructed above the existent hardware environment of Intranet/Internet. And it comprises shapes database, cutting information database, clamping tools database, processes database, NC codes database and any other relative database. There are six parts modules in INC system. They are CAD parts module, CAPP parts module, optimizing and decision parts module, CNC parts module, system monitor parts module and general planning parts module. CAD parts module has the functions of completing the design of products shapes oriented to CNC manufacturing. It also includes the VQ function of the planar engineering patterns, three-dimensional drawing’s projection to planar face. The final objective of this parts module is to generate standard dxf or dwg files for the next step.
CAPP parts module does the work that pick-up of some points in process planning, cutting path selection,
inserting points in cutting process, process analysis and process design. It directs the CAPP executor to finish the process plan of the parts. Optimizing and decision parts module carries out the optimization, management and decision of the whole process plan. If there is a batch operating or multi-parts operating, it is to be considered to optimize the cutting path design, time reckoning, cutting tools changing, cutting fluid using, technological points inserting and so on. These functions are oriented to the whole process plan.
CNC parts module is the heart of INC system. It
finishes the work of general CNC, such as code explaining, interpolation, servocontrol and sampling, user-machine interactive interface, PLC control and so on.
System monitor parts module does the work of collecting and sampling the information for single CNC machine or the whole CNC machine group. It includes
monitoring of system state, getting operating data, and remote control functions.
General planning parts module is used when the INC system manages with a group of CNC machines. It
harmonizes whole paces of the system, administrates the allocation of whole machine resource. It not only runs the products’ programs and machines’ programs, but also makes the total production plan and makes the schedule of working procedure.
3.2. Key technologies of INC Because INC is an integrated and intelligent CNC, its key technologies not only include the technique of CNC, but also include extra integration and intelligentization technologies. And we conclude there are three kernel technologies should be considered: CAD technology oriented CNC ( CADoCNC ), CAPP technology oriented to CNC ( CAPPoCNC ) and CNC technology based on CAD/CAPP ( CNCbCAD/CAPP ). CADoCNC includes image preprocessing technology,
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
intelligent recogonition technology, image vector quantization (VQ) technology and CAD/CAPP integration technology, etc. CAPPoCNC includes path optimization technology, nesting optimization technology, CAPP/CAM integration technology, engineering database creating and administering technology, etc. CNCbCAD/CAPP includes programming technology for device drives, interface and interactive technology with CAD/CAPP, embedded system and microcontroller technology, etc. And about system monitoring parts module and general planning parts module, they may involve signal processing technology, MIS (Management Information System) technology and some other relative technologies. 4. Some intelligent characteristics of INC 4.1. Image recognition and VQ capability In the traditional CNC manufacturing process, CNC can just cope with G-code files. If there has a CAD/CAM
transferring system, dwg/dxf files of CAD may be turned
into G-code files before it is inputted to CNC. But there
hasn’t a good way to deal with some engineering blue prints,
drafts drew by hand, scanned bitmaps, and digital photos.
There has been a long history in image process research
field, and some scientists have gained great achievements in
that field. But there has no good case or software
successfully used in engineering area. CAD parts module
has the function of automatically transferring not only
AutoCAD file but also the above all kind of patterns to G-code file. It is worthwhile and meaningful solving how we can use so great many and abundant of above patterns to CNC manufacturing for engineering application.
The image recognition and VQ technology of CADoCNC is to solve how to change the existing patterns or drawings to vectorgraphs, and then we can do the next optimizing design on the basis of it. The designer will not need to waste time working on drawing transform or input, they can concentrate on product design instead.
The above four kind of patterns can be got by scanning or taken by digital camera. The outlines of the objects in these patterns are the base of NC machine manufacturing. Before we have a standard vectorization conversion, we should change various colorful original patterns to
monochrome outline profiles. The preprocessing course comprises grayscale, smooth, denoise, binarize, pattern morphologic combinatorial denoise and find edges. The preprocessing flow chart is shown in figure 3.
And then we can do the next step: vector quantization. There are three popular approaches used in modern vector quantization: holistic identifying approach, outline tracking & matching approach and the approach based on thinning.
General engineering pattern or drawing is composed of some complicated line styles. And the image after vertorizing with the approach based on thinning, the elements of which can be easy to be linked and matched
with line or arc. This algorithm is also easy to be realized by the program. Furthermore, it can be easy to be fit and standardized with the line and arc styles defined by dxf file, so that it can be easy to be distilled to control and modify
the line and arc information during CAM process. It is easy to be edited and accessed when it is integrated in the CAD/CAM module, so we use this algorithm to vectorize the image. We adopt a sequential algorithm based on
mended-template to get a binarization image. Then we use
chain-code to vectorize the image further. The image after chain-coding can be easy to get geometrical information of
it, and be convenient to straight line fit or arc fit and be identified. Moreover it can greatly save the memory space
and be easy to be condensed.
Figure 3. Image preprocessing course Freeman chain-code approach [7] is a generally used way to change monochrome image to chain-code file. Freeman chain-code looks the binarized image as a gridded image, and it uses direction of adjacent points to express a coherent curve. We adopt 8-area Freeman chain-code approach to connect adjacent points to a coherent line or
curve. After chain-coding, the image is convenient to get geometrical information of elements in it. Moreover, it can be easy to be transferred to a standard AutoCAD dxf file. After that, we can carry out straight line fit and arc fit, and finish vectorization process.
The image after VQ has distilled the geometrical information of straight lines and arcs. If we explain it in an intrinsic format, we can get the standard dxf file. Dxf format is a popular format used in modern CAD system and
CNC industry. It is a special ASCII text file, which can be opened and modified with all kind of text editor. Different
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
versions of AutoCAD may have something difference in
dxf format, but the frameworks of them are similar. We
adopt the format of AutoCAD2000 as standard for the
saving format of verctorized files [8]. It can be accessed
and modified by AutoCAD software.
4.2. Intelligent process planning capability After CAD parts module, we have accomplished the geometrical modeling of parts. How can we make a process planning effectively and efficiently? We need to design the CAPP parts module, which is based on CAPPoCNC. It is particularly conceived to be performed easily in CNC, so it is oriented to CNC manufacturing. According to manufacturing process, it is a rich area. Different kind of products has different manufacturing methods. Here we consider general cutting machine as studying object. Supposing it is a two-dimensional cutting process, process planning need to specify the additional technical parameters based on the design: such as tolerances, manufacturing precise, cutting speed, cutting path, nesting optimization, clamping tools, etc. We must synthetically consider these facets that we can produce satisfied products. CAPPoCNC is the bridge between CADoCNC and CNCbCAD/CAPP.
CAPPoCNC includes path optimization technology,
nesting optimization technology, CAPP/CAM integration
technology, engineering database creating and
administering technology and so on. And there are fuzzy
process knowledge representing, fuzzy decision and
reasoning mechanism running in the background. The flow
chart of CAPP parts module is shown as figure 4.
Figure 4. Flow chart of CAPP parts module As is shown in figure 4, First we got a AutoCAD
design from patterns database or last step, second we must
specify cutting parameters such as cutting tools, cutting
speed, idle motion speed, cutting solution, clamping tools,
etc, and working procedure such as original point, technical
points, start point, end point, cutting path, cutting sequence
and so on. Some parts using a special technology need to be
considered particularly, such as parts motion and rotation,
arc forward and back cutting, cutter compensation and so
on. Sometimes we not only consider a single part
manufacturing, but also consider a batch production. We
need to do path optimization and nesting optimization.
Aiming at a lot of fuzzy information and fuzzy effects in
CAPP, we adopt a general kind of fuzzy comprehensive
evaluation according to fuzzy consistent matrix and gray
system [9]. In the next paragraph, case study, we can see
how CAPP parts module makes man-machine interaction. 4.3. Simulation Simulation is one of the most widely used operations research and management-science techniques. With the development of modern science, technologies of computer processing and image display are greatly enhanced. It makes it is possible to simulate the actual manufacturing in the computer. An intuitionistic and effective CNC simulation had better be based on a friendly graphic user interface, so that users can have a good comprehension of the whole manufacturing process. We can test rationality of the design and feasibility of technologic parameters. Also we can test if there is any interference phenomenon. CNC manufacturing simulation is to simulate manufacturing process on the base of G-code files directly. It not only tests the process of actually machining, but also
includes some extra functions, such as code debug, edit,
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
save, system monitor, etc.
In INC, the simulation module has replaced traditional trying out process in the machine. It shortens the machining cycle of products. And it can avoid the wear and tear of cutter and parts by a simulative interference check. It is an intelligent element that integrates other elements of INC, such as CAD, CAPP, CNC or CAM to a complete unit or entity.
5. Case study
We have done researches on INC upon Windows, Linux and embedded Linux platform. Here we depict working process of INC under the Windows-based environment as an example. All the researches and development of Windows-based INC system were based on AWJ (Abrasive Water Jet) cutting machine. AWJ (Abrasive Water Jet) cutting machine is a patented product of Shanghai University JiRen Co ltd & Shanghai University of China. AWJ cutting machine cuts components by water mixed abrasive via high-pressure tube. We explain how to realize a narrow-sense INC based on this.
Now we have got a pattern of a digital photo as top left part of figure 5. It is a finished product of a kind of ceramic
tile.
Figure 5. Image preprocessing module
As it is shown in figure 5, we can see how image preprocessing course goes on clearly. In the second part, we get a grayscale image; in the third part, we binarize the image; in the fourth part, we denoise the image, and then we find the edge, finally we got a clear outline.
After VQ process, we get a standard dxf file, and we import it into our CAPP parts module, as it is shown in
figure 6.
Figure 6. CAPP parts module interface
AutoCAD has been embedded in this module, and we can perform all the CAD functions via that interface. In the left of figure 6, we can design and modify our drawing in that area. And in the right, it is a CAPP plug in module, where we can get points, lines, layers, dimensions, direction and some process parameters easily and we can generate G-code text for the next step. We could interact with CAD system via this module, where CAD information can also be transferred to CAPP information in the background.
Figure 7. NC Simulating module interface Finally we jump into the simulating module emulating the actual manufacturing, which can be also run in the actual machine, as it is shown in figure 7. In the top left part of figure 7, it is a cutting process display, where we can have an intuitionistic cognition of cutting path, cutting velocity, current coordinate and so on. We also can know the information of components’ shapes, the amount, path we have finished, and path left. In the top right of figure 7,
Proceedings of the Fourth International Conference on Machine Learning and Cybernetics, Guangzhou, 18-21 August 2005
it is a frame where numerical code is shown. We can check it, modify it and save as a new one. The bottom of the interface has some parameters listed and adjusting buttons.
Now we finish a cycle from a digital photo of a finished product to a new product machining in INC.
6. Conclusions and perspective
This paper proposes a new philosophy of CNC - INC. It is a new conception in CNC field which gives an integrated theory oriented to manufacturing. And paper emphasizes on discussion and analysis of its key technology and intelligent characteristics. It also gives a case study about INC realization in the engineering field.
INC – with a friendly interface based on graphics and special tools – is such a system replacing distributed manufacturing with collaborative manufacturing that it is a novel philosophy using a cost-effective means to directly facilitate the manufacturing to enhance productivity. It is an integrated manufacturing or intelligent manufacturing.
As far as its special technologies are concerned, they are very useful for engineering application. Such as CADoCNC, it solves the problem how to change the existing engineering patterns, drawings and digital photos to standard AutoCAD files. Designers will not need to waste time working on drawing transform or input; instead they can concentrate on product design. It also solves the problem of CAD/CAPP integration, which links CAD/CAPP with manufacturing tightly. Acknowledgements
This research work is financially supported by the Science and Technology Development Foundation of Shanghai Science and Technology Committee (036505008 and037252022). And it was supported by Shanghai University JiRen Co ltd and Shanghai Third Printing Machine Company of PR China.
References
[1] John V Farr. Dennis M Buede, “Systems engineering
and engineering management: Keys to the effient
development of products and serives.”, Engineering
Management Jounnal, Vol 15, No. 3, pp. 3, Sep. 2003 [2] Shuzi Yang, “Trend in the development of advanced
manufacturing technology”, Chinese Journal of Mechanical Engineering, Vol 5, No. 1, pp. 73-77, Dec.
2003. [3] Yulong Wang, “Open architecture for CNC controller
and their developing prospect”, CNC & Software, pp.
75-76, Apr 2004.
[4] Junli Gao, Di Li, ShiXiong Zheng, and Shouting Feng,
“Building open computer numerial controllor”, Combinatorial Machine & Automatic Manufacturing
Technologies, pp. 55-57, May 2004.
[5] P. Stout, and R. Leonard,“The introduction of DNC
technology as a partial approach to achieving the
objectives of CIM”, Computer-Aided Engineering
Journal, pp. 17-20, Feb 1989..
[6] Tan Liu, Tao Yu, Wenbin Wang, “INC: A New Type
of Computer Numerical Control”, Proceedings of the
Ninth International Conference on Computer Supported Cooperative Work in Design, Coventry,
UK, May. 25-27, 2005, Have been accepted.
[7] Guodong Lu, Shuyou Zhang, Digital transform and
intelligent understanding of engineering patterns, Machinery Industry Press, Beijing, China, 2001
[8] Shiguo Li, AutoCAD Super Developing technology –
ARX Programming and Application, Machinery Industry Press, Beijing, China, 1999.9
[9] Weiyue Xiao, Intelligent Information Porcessing
Technology in CAPP, National Science Publisher,
Changsha, China, 2002.