Study Of Modelling And Development Environment For Virtual Manufacturing Systems- Ashwin Thottumkara Full Report

LIST OF FIGURES

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Basic structure of VMS

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Working of VMS

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Developing environment for VMS

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ABSTRACT 1

For adapting the demands of the rapid changing and enhancing the competing capability of enterprise in the international market, various modern manufacturing systems have been put forward, which are aimed at various specifications, perfect performance and high quality, low production cost and short manufacturing cycle of products, virtual manufacturing system (VMS) has been emerged as the times require, which is effective technology to meet the challenge of 21 century's manufacturing industries. Based on analysing modern manufacturing systems, according to the characteristics and requirement of VMS, in this paper, the architecture, the key technologies and the implement way of VMS were explored, and development environment for VMS was put forward, which is a powerful tool for building VMS.

Chapter 1

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INTRODUCTION With the development of science & technology and increasing social demands day by day, the new requirements of property & specification and type of products will generate changes continuously, and the products' life cycle are more and more short. In order to adapt the demands of market changing, small batch and multibreed production will play an important role, the cycle of products' developing and manufacturing has to be shortened greatly, and production has to be organized and implemented rapidly and agilely. For this, many new ideas, new concepts and new methodologies are proposed, many new manufacturing systems, such as Flexible Manufacturing System (FMS), Computer Integrated Manufacturing System (CIMS) and Intelligent Manufacturing System (IMS) and so on have emerged. These systems possess the characteristics of flexibility, integration and intelligence, which will improve the products quality, raise productivity, shorten the design and manufacturing cycle of products, decrease the cost and enhance the competing capability of enterprises. But, there are still some problems in this system, which can be summarized as follows. (a) The manufacturing environment is very complicated and easy change. Due to changes of the products type and the associated production procedure, production organization needs a lot of labours and material resources, assets and time; meanwhile the market is rapidly and unexpectedly changing. The needed investment for establishing these systems is very high. But, there are no effective methods to know about the value for developing a new product before a lot of labours and assets are put into, and there are no effective methods to effectively evaluate the benefit gained and the risk borne before a system is established for producing this new product developed. (b) The system, such as the present FMS,CIMS,IMS and so on, can gain better economical benefit, but they can only bring the local superiority into full play, can not bring the synthetically superiority of the enterprise group. However, VMS can bring the whole superiority of human and material resources and technologies of enterprise group into play. (c) It has none ability to get the real activities of the every manufacturing phrase at the every phase of products 3

development, and can not cooperatively solve the problems between design and manufacturing procedure in order to look for the global optimum decision for the whole enterprise. (d) Although the above mentioned systems put emphasis on the integration concept, the attention of them is different, such as CIMS lays emphasis on "information” integration, IMS lays emphasis on "intelligence" integration. When a modern manufacturing system is developed, the "Overall Integration Concept (OIC)” should be emphasized. OIC includes information integration, intelligence integration, sequence/concurrent

working

mechanism

integration,

and

human-machine

integration. In order to get the target of the global optimization, the distributed concurrent intelligent cooperation solution systems are required. For solving the above problems, Virtual Manufacturing System (VMS) was putted forward (1-3). VMS is called as the new production paradigm, which is effective technology to meet challenge of 21 century's manufacturing industries. The commencement of VMS is the inevitable results of the development of modern science & technology and production techniques, which is the inevitable tendency of the development of modern manufacturing systems. Based on the synthetically application of multi – subject advanced knowledge, A VMS can real- time and concurrently simulate the future manufacturing overall procedure at the product design phrases, and find out its influence to the design, evaluate the product performance, estimate the product manufacturing cost and manufacturability, and so as to more effectively and more economically organize production, make the design and layout of workshop and factory more reasonable and more effective for getting the shortest cycle and the lowest cost of product developing, the optimization of product quality and the highest productivity. The products manufactured by VMS are numeral products that can be viewed, and they possess the features which are appeared with associated real physical products. VMS involves various aspects for product development and manufacturing procedure, it is synthetically application mullet- subject advanced technologies such as computer network technology, computer graphics, CAD/CAM technology for mechanical and electronic machines, AI technology, computer simulation technology, integrated

engineering

analysis

technology, concurrent engineering,

system

engineering, virtual realty technology, and visualization technology and so on. VMS 4

based on distributed concurrent processing environment supplies a new effective tool for designing & manufacturing of products, which meets there requirements of the more and more violent competing of the market. It not only influences the future mechanical and electronic product design pattern, and the type of production organization and management, but also effectively evaluates the benefit gained and the probable meeting risk of developing new products and organizing production, thus, the enormous benefit can be get for the enterprise.

Chapter 2

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THE SYSTEM ARCHITECTURE OF VMS

VMS is description of formulated, computerizing and modularizing for the RMS (Real Manufacturing System).It consists of the corresponding models which are mapped on VMS by models of the RMS, and the manufacturing procedure can be simulated with these models in the computers. The RMS consists of material flow, information flow and energy flow, which makes related decision at the various levels with control mechanism, and implements the transfer from input to output. The main bodies of a RMS are the material flow and the information flow, in a few words; the main sub-systems of RMS are Real Information System (RIS) and Real Physical System (RPS). With analysing and abstracting of RMS, RMS can be described by the following formulation. RMS = {RPS, RIS, RMCS, RES}.................................... (1) Where, RPS is the real physical system; RIS is the real information system; RMCS is the real monitoring and controlling system; RES is the real energy system. (a) RPS consists of physical entities existing in the real world, such as material,

parts, products, machine tools, jigs, robots, and so on. When a manufacturing system is operated, these entities possess the physical behaviours and interactions, such as motion, transfer and transformation. RPS can be described as follows. RPS = {PS, DS, M-CS, . . . _RMS }.............................(2) Where, PS means the product system, which includes material, intermediate products, target products.

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DS means the device system, which includes machine tools, cutting tools, jigs, robots and transporting equipments and so on. M-CS means the monitoring and controlling System, which includes sensors, monitors and controllers. (b) A RIS involves many activities of information processing and making

decision, such as design ,planning, scheduling, controlling, estimating. It consists of not only static information of design and manufacturing procedures, but also the dynamic information of design and manufacturing procedure. ARIS can be represented as follows. RIS = { TIS, MIS, DIS, . . . . . . , _RMS }.......................................(3) Where, TIS means the Technology Information System; MIS means the Management Information System; DIS means the Decision Information System; (c) A Real Monitoring and Controlling System (RMCS) monitors and controls the

total manufacturing procedure, which is a function of RIS and time t, and it can be presented as follows. RMCS = f (RIS, t).....................................(4) (d) A Real Energy System (RES) supplies energy for manufacturing system being in operation, which includes human- power resources and other power resources, it can be represented as follows. RES = {Human-E, Power-E|_RMS } ......................5) VMS is the mapping of the RMS in the virtual environment, which is supported by multi-subject advanced technologies, such as distributed intelligent cooperation solution technologies, computer simulation technologies, and so on. It can be represented as follows: RMS —→ VMS..................................... (6) Thus, 7

VMS = { VPS, VIS, VMCS, VES }......................................(7) Where, VPS is the virtual physical system; VIS is the virtual information system; VMCS is the virtual monitoring and controlling system; VES is the virtual energy system. VPS is the mapping of RPS in virtual environment with distributed concurrent processing function, which consists of the related models formulated, computerized and modularized of RPS, which have the same functions appeared with the real physical entities. VPS can be described as follows: RPS —→ VPS (4) VPS = { VP-S, VDS, VM-CS, V Cell, V Workshop . .. _RMS} .................. (9) Here, VP-S means the virtual product system, which includes material models, intermediate products models, target product models . VDS means the virtual device system, which includes machine tool models, cutting tool models, jig models, robot models and transporting equipment models. VM-CS means the virtual monitoring and controlling system, which includes sensor models, monitor models and controller models. VCell means the virtual manufacturing cell; which is the mapping of the real manufacturing cell. V Workshop means the virtual manufacturing workshop, which is the mapping of the real manufacturing workshop. The basic components of VCell and V Workshop are VP-S VDS, VM-CS. Similar to above subsystems, the other virtual subsystems corresponds to the corresponding physical subsystems, and it is only to become “real” into “virtual The basic structure of VMS is shown in figure 1, which can be divided into three levels: management decision level, product decision level and production decision level. In management decision level, according to the requirements of users, market information, the developing schedule of enterprise and resource condition as well as the enterprise techniques level, the kinds and specification of products, production scale are decided. In this level, owing to changeable market information, more uncertain factory, the

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intelligent management decision support system needs to be developed by using fuzzy decision and artificial intelligence technology.

In product decision level, according to the above decisional the constrained condition of technology performance, applied resource, working environment, cost and so on, the optimum structure scheme of product with maximum economical benefit are decided. Figure 1 the Basic Structure of VMS In production decision level, according to the above Decision, human -power, material resources, techniques Resources and level, and so on, the product design, Process planning, the schedule of production task and The production dispatching plan is decided, and manufacturing process in the virtual environment is implemented. With above three decision levels, which are supported? By the unified software and hardware environment, Cooperative solving can be carried out for getting the Global optimum solution of the overall system The basic working flow of VMS based on the above Analysis is shown in Figure 2. 9

Chapter3

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THE BASIC REQUIREMENTS FOR CONSTRUCTING VMS FUNCTIONAL COMPATIBILITY A VMS should have the same functions to the Corresponding RMS. The information and control Demands, which are generated/sent by VIS, should be Equivalent to the same function of the corresponding IS. VPS responses control demands and returns Status reports from and to VIS, which should be completely equivalent to the same function of RPS. The Communication and information exchanging between Viand other VIS, VIS and VPS, and in VIS, should be done well. Virtual Environment In production decision level, according to the above decision, human -power, material resources, techniques resources and level, and so on, the product design ,process planning, the schedule of production task and the production dispatching plan are decided, and manufacturing process in the virtual environment is implemented. With above three decision levels, which are supported by the unified software and hardware environment ,cooperative solving can be carried out for getting the global optimum solution of the overall system .The basic working flow of VMS based on the above analysis is shown in Figure 2

STRUCTURE ANALOGY

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The structure of the VMS is required to be analogous tithe structure of the corresponding RMS. The structure alikeness can provide VMS designers and operators with the intuitive way of the system definitions and modification.

FLEXIBLE ORGANIZATION The organizing and implementing of a VMS should be highly flexible, for adapting to the requirements of the future manufacturing systems, the market and the users. When the manufacturing systems are established, the method based on modular and object- oriented technologies can be used. Reuse and reorganization offal kinds of models, and the combination of various models should be interested in

INTELLECTUALIZATION Expert system and artificial neural network will be applied to relevant link of VMS. Its focal points are the distributed concurrent intelligent solving system and the Global optimization decision in the virtual environment

VISUALIZATION Although the VMS is run under the virtual environment, all the states of every working process and the conclusions should be visible. The problem of visibility Can be solved by applying computer visualization and multi-media technologies.

Chapter4

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DEVELOPING ENVIRONMENT FOR VMS According to the differences of products and the manufacturing environment and enterprise resource, the total architecture of manufacturing system might be different. Thus, for adapting different situation, a flexible and convenient developing environment for modelling, organizing and constructing VMS must be supplied. The Development environment is divided into three levels, as shown in Figure 3.

COMPONENT LEVEL

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This level offers all the component and models for describing the virtual manufacturing activities and their entities. It mainly consists of two bases. One is Component base, which supplies all the components needed when a VMS is constructed, the components can be selected by the requirements of building the VMS. Another is decision base, which supplies various methods of decision in constructing and executing procedure of the VMS.

DEVELOPING LEVEL This level provides a developing environment for establishing VMS, which involves various techniques, tools and approaches. In this environment, required Methods, techniques and software of the product design and process planning, production organization and management, production realization, evaluation of Benefit & risk and so on are organized according to requirements manufacturing procedure. When VMS is constructed, the aim and the function of which are used as input, the task scheme tree and the system architecture tree are formed by using casebased expert System technologies, according to these trees the required VMS is formed with utilizing the tools provided by integrated development environment.

APPLICATION LEVEL Besides running and checking the formed VMS, this level can also offer application interface for user using the formed VMS and carry out the simulation of working procedure of the formed VMS.

Chapter 5

THE KEY TECHNOLOGIES OF VMS 14

VMS is a new concept in the world. Its theoretical basis is not formed completely. The research work is still at the primary exploring stage and it must be faced with the intersection of multi-subject, the synthetically application of many kinds of new advanced technologies. Though the problems needed to research and solve are very much, we suppose that we should fully utilize gained achievement in the research of CIMS and IMS. We should focus our attention on its basic theory and key technologies. The main contents are shown as follows. (a) The theory basis and system architecture of VMS, specifically, the study of the

open system architecture of the virtual manufacturing system (VMS- OSA) based on distributed concurrent processing environment. (b) The product master model technology in virtual environment. The master

model is a core, it can serve as a centre to lead to design, manufacturing, production management, and so on. The master model has unified data structure and distributed data management system. The product model established by master model is virtual product model. It is a numerical model and it possesses all features of represented object. Virtual products have existed before they have been really produced, which have obvious visibility.

(c) The technology and system of distributed intelligent cooperation solution in

the virtual environment. (d) The theory and technology of the global optimum decision in the virtual

environment.

(e) Building the mapping relation between RMS tandems, the virtual equipment, virtual sensor, virtual cell, virtual producing line, virtual workshop, virtual factory and the reorganization of all kinds of virtual equipments are researched and built.

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(e) Based on lively animated cartoon, the simulation for the virtual products

assembly, the production dispatching and manufacturing procedure, NC machining and so on. (f) The components base and user integrated development environment of VMS,

and self-adaptive intelligent interface

(g) The strategies and technologies of organization, dispatching, controlling for a

virtual company. (I) the research on visualization technologies based on multimedia technologies

. Chapter 6

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CONCLUSION VMS is a newly emerging thing and the inevitable tendency of the modern manufacturing industries, which is the outcome for adapting changeable market Requirement and enhancing enterprise's economical benefit. Theory architecture, key technologies of VMS will need to be discussed and developed further, many Technologies and ideas of CIMS and IMS can be utilized. The ideas and methods put forward in this paper provide the certain theory basis for the development of VMS

Chapter8

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REFERENCES 1. Onsite, M., Iwata, K., 1993, Development of a Virtual Manufacturing System by Integrating Product Models and Factory Models, annals of CIRP, 42, 1, 475-478. 2. Kimora, F., 1993, Product and Process Modelling as a Kernel for Virtual Manufacturing Environment, annals of CIRP, 42, 1, 147-150. 3. Q.K.Yuan, 1995, Virtual Manufacturing System, China Mechanical Engineering, Vol.6 (4):10-12. 4. Q.K.Yuan, 1998, the Study of Virtual Manufacturing and Its Master Model Technologies, PhD Thesis, Xi’an Jiao tong University. 5. Q.K.Yuan, 1999, the Study of Virtual Manufacturing and Its Key technologies, Automation Technology for Industry, Vol.6 (3): 26-32.

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