Collaborative Fixture Design and Analysis Using Service Oriented Architecture

IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING, VOL. 7, NO. 3, JULY 2010 617

Collaborative Fixture Design and Analysis UsingService Oriented Architecture

Liqing Fan, B. N. Jagdish, A. Senthil Kumar, S. Anbuselvan, and Shung-Hwee Bok

Abstract—Distributed collaborative design and manufacture en-ables manufacturing organizations to seamlessly collaborate witheach other to design and manufacture products with shorter leadtime. This requires the distributed system not only to maintaindata consistency across globally distributed locations seamlessly,but also allows team members to access the services securelyand transparently. In addition, appropriate information modelsneed to be developed to facilitate design data exchange betweendifferent domains. This paper reports on the development of adistributed collaborative system by addressing the above issuesand demonstrating the developed system using fixture design andanalysis as a case study. Web services and service-oriented archi-tecture (SOA) are employed in this system to address the issues ofinteroperability, platform-independence, and language neutrality.Information exchange models based on XML schema have beenused to facilitate data transfer between design and analysis.

Notice to Practitioners—The main objective of this work is toprovide a suitable framework and methodology that can aid theprocess of collaborative fixture design and analysis. This is drivenby the need for collaborative product development in a distributedenvironment pursuant to outsourcing and increasing competitionfor timely design alternatives and their complete realizationand delivery. Our approach demonstrates seamless informationsharing through the use of SOA. In this paper, the usefulness ofthe developed system is demonstrated using the developed fixturedesign system as a case study. In the first step, we have shownas to how the fixture design system will enable the user to designa fixture for a machining part with the fixture elements from apreloaded fixture element library using rules. We then show howfixture design can be integrated with fixture analysis through theuse of XML schema and a messaging service. For fixture analysis,the user needs to only enter key data like material properties,machining data file name and clamp pressures while the fixtureanalysis procedure is automatically done using Patran. After theanalysis is completed, the user can then download the HTMLreport file that contains some critical information such as stress ofthe workpiece, displacements at contact points between the work-piece and fixture elements, etc. This report helps the designer toevaluate the quality of the fixture designed and to make a furtheraction, e.g., to redesign the fixture or to just reposition a fixtureelement. These enable users to have a quick assessment of their

Manuscript received March 22, 2009; revised July 29, 2009 and September13, 2009; accepted October 19, 2009. Date of publication February 02, 2010;date of current version July 02, 2010. This paper was recommended for publi-cation by Associate Editor J. Xiao and Editor V. Kumar upon evaluation of thereviewers’ comments. This work was supported in part by the National Univer-sity of Singapore and Infocomm Development Authority of Singapore (IDA).This paper was presented at the IEEE Conference on Automation Science andEngineering (CASE) 2008, Washington, DC.

L. Fan, B. N. Jagadish, and A. S. Kumar are with the Department of Mechan-ical Engineering, National University of Singapore, Singapore, 119077, Singa-pore (e-mail: [email protected]).

S. Anbuselvan and S. H. Bok are with the Department of Industrial SystemsEngineering, National University of Singapore, Singapore, 119077, Singapore.

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TASE.2009.2038069

fixture design without much knowledge of FEA. However, thismakes users not fully in control of the process of fixture analysis.In order to allow a user to manage and create his simulationprocess, workflow using templates will be further explored in thefuture work.

The current system has been designed to handle prismatic work-pieces. In the future, the issue of handling workpieces with morecomplex topologies will be addressed.

Index Terms—Collaborative design, fixture analysis, fix-ture design.

I. INTRODUCTION

D YNAMIC markets, customer demands, and the competi-tion in product development drive the need to lower cost

and reduce product development cycles and manufacturing leadtimes. In addition it is common nowadays to see designers out-source the manufacturing activities to different organizations.In order to realize a seamless integration between them a trulydistributed product development environment is necessary andthis will help globally distributed manufacturing organizationswith different expertise to come together to design and manu-facture a product rapidly. Such an efficient distributed systemmust have the ability to maintain data consistency across glob-ally distributed locations and allow the team members to accessthe relevant information transparently and securely.

Fixtures are work-holding devices, which are used in ma-chining, assembly, inspection and other manufacturing opera-tions to consistently maintain the desired position and orienta-tion of the product [1]. Design of such fixtures require infor-mation from both the product designer and the manufacturingengineer.

In industry, development of new fixturing solutions for com-plex workpieces is still based on designers’ experiences andinvolves manual prototyping and testing. This leads to highercosts and longer lead-times, especially when ineffective fixturedesigns (FDs) have to be iteratively improved, prototyped andretested. Therefore, a number of urgent problems need to be ad-dressed in order to support collaborative design and manufac-turing applications effectively:

• Compatibility problems: In today’s product developmentenvironment, team members from different companieswork together to realize a product. However, the use ofdifferent software may cause a compatibility problem.

• Collaborative platform for FD and analysis: This will en-sure timely information sharing, maintain data consistencyand enable globally distributed organizations to effectivelycollaborate and finalize the FD.

• Managing information exchange between FD and anal-ysis: Product design data and knowledge are not only man-

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618 IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING, VOL. 7, NO. 3, JULY 2010

Fig. 1. The system architecture based on SOA.

Fig. 2. FD sequential workflow at client side (solid line represents the inter-action between processes, and dash line the interaction between processes andclient gateway).

aged by the design and production activities, but also re-quired in the downstream applications of the product de-velopment process to carry out their tasks. Meanwhile, up-stream applications need feedback information from thedownstream applications for validation or optimization.

This paper reports the development of a distributed collabo-rative system for integrated fixture design and analysis (IFDA)addressing the above mentioned challenges. In this system, webservice and service-oriented architecture (SOA) are adopted in

order to facilitate their interoperability. This will enable smallto medium sized enterprises to effectively use these services ac-cording to their needs. IFDA is developed as a “single window”solution to design a fixture interactively and conduct fixtureanalysis using the finite-element method (FEM). This projectaims to provide an environment that is scalable and robust forbuilding enterprise applications.

This paper is organized as follows. The relevant researchworks are discussed in Section II. Section III proposes thesystem architecture for IFDA with web services and SOA.Section IV describes the FD process within the proposedsystem. Section V describes the FD information exchangemodel, while Section VI presents the fixture analysis process.Section VII presents a case study followed by conclusions.

II. REVIEW OF RELATED RESEARCH

A. Fixture Design and Analysis

Designing a fixture involves fixture synthesis and fixture anal-ysis. Fixture synthesis determines the areas on a workpiece forlocating, supporting and clamping; and their associated fixtureelements. Fixture analysis aims to arrive at an accurate math-ematical model to verify and evaluate the fixture configurationduring the machining process in terms of stability, total restraint,accessibility and deformation. The prominent approaches forfixture analysis are kinematic, force and deformation analysis[2]. In this paper, FD usually refers to fixture synthesis.

FAN et al.: COLLABORATIVE FIXTURE DESIGN AND ANALYSIS USING SERVICE ORIENTED ARCHITECTURE 619

Fig. 3. Iterative diagram for FD process.

Fig. 4. DTD for FD configuration.

Fuh et al. [3] presented an approach to integrate FD and anal-ysis using a rule-based approach. Pelinescu and Wang [4] de-veloped an iterative algorithm for fixture synthesis and evalu-ated the designs with respect to location accuracy and locatorcontact forces. Roy and Liao [5] developed a fixture synthesisalgorithm based on a 3-2-1 locating principle and heuristics. Sta-bility analysis based on screw theory was carried out to providequantitative design analysis for the reallocation process.

In order to analyze the displacement and deformation of theworkpiece and fixture elements, FEM is commonly employedin fixture analysis. Roy and Liao [6] developed an iterative al-gorithm for fixture synthesis with a set of heuristic rules. Thefixture analysis module uses finite-element analysis (FEA) toolsfor stress and deformation calculations. Kaya [7] calculated dis-placements using FEA and these values formed the input for anoptimization program using genetic algorithm.

However, all the research works reviewed by the authors fo-cused on the development of standalone systems, and they aregenerally specific to a CAD system. To the authors’ knowl-edge very little research has been reported in the area of dis-

Fig. 5. DTD for boundary condition definition.

Fig. 6. DTD for result file.

tributed design using heterogeneous platforms over the network.Wagner et al. [8] have implemented a FD system over the WorldWide Web (WWW) known as FixtureNet. The drawback of thissystem is the part is described by its silhouette, i.e., in a 2-Dform. This could result in a loss of information that could aidin arriving at an optimal fixture configuration. Mervyn et al. [9]implemented an Internet-enabled interactive FD system basedon a three-tier client-server architecture. The information andknowledge are transferred using XML as a file format via theInternet.

These two distributed FD systems reviewed above, how-ever, were only designed and developed for fixture synthesis.Fixture analysis, an important task in the FD process, was notconsidered.

B. Distributed Collaborative Design Systems

Various distributed collaborative applications have been de-veloped for different engineering domains using various system


Fig. 7. Fixture analysis process.

architectures. The architecture of integrated systems can be di-vided into three types based on the visualization and geometrykernel, as well as system openness and extensibility. These threetypes are client-server based tightly coupled structures, middle-ware-based coupled structures and loosely coupled structures.

In the first type, the whole geometry kernel is put in eachclient and the central server acts as an information agent tobroadcast CAD model and commands generated by one client tothe other clients [10]–[14]. A tightly coupled structure is simpleand easy to realize. Standard CAD systems can be convenientlydistributed through this mechanism. However, the interfaces be-tween systems must be customized and the communication pro-tocols must be strictly matched. Any change will lead to recom-piling and redeploying all program modules.

Middleware-based structure, in general, is a set of layers thatsit between application and commonly available hardware andsoftware infrastructure in order to make the system structuremore flexible. In the middleware-based structure, the geom-etry kernel and the models reside in a server and clients havelightweight interfaces to display models for visualization only[9], [15]–[20]. Some of the data processing logic is enclosed inthe middleware, which makes the coupled systems more inde-pendent. In this way, data consistency is easily kept since theprimary models are created and maintained in the server. Somerecent technologies like CORBA, Java RMI, and Microsoft’sDCOM are used to implement a distributed collaborativesystem. However, the incompatibility of interface and com-munication protocol among the technologies has become themain barrier to effective collaboration among heterogeneoussystems.

SOA is one of the promising concepts to have emerged in en-terprise architecture circles, presenting an approach for buildinga distributed system that delivers application functionality asa service to end-users. These application services are looselycoupled, independent, and can be distributed across a network.These services communicate via a standardized, platform-inde-pendent protocol that hides the underlying implementation de-tails of each service. A service can be implemented either inMicrosoft .net or J2EE, for example, and the application con-suming the service can be on a different platform or language.

SOA can be implemented using several technologies, but themost common choice today is the use of web services. Web ser-vices provide a standard means of interoperating between dif-ferent software applications, running on a variety of platformsand/or frameworks [21]. The main technologies of web services

like SOAP, WSDL, and UDDI are all based on XML that formsthe basis of web services’ platform-independence and provideslanguage-neutrality. Thus, web services show undoubted advan-tages in addressing heterogeneity.

Based on the current main frameworks supporting web ser-vices, J2EE and .NET, the software development industry hasprovided several SOA platforms, such as IBM’s WebSphere[22] and Microsoft’s BizTalk [23]. However, the integrated plat-forms are mainly involved in e-business and e-governance, anddo not have the specialized characteristics for the engineeringdomain. So far, only a few reported research works have em-ployed web-service-based SOA for distributed collaborative de-sign and manufacturing. Shen et al. [24], [25] proposed a ser-vice oriented integration framework used to establish a dynamiccollaborative environment for manufacturing resources sharingbased on software agents and web services. Dong et al. [26] alsoproposed a web-based extended manufacturing resource servicefor product development with SOA. In order to facilitate designand manufacturing process integration and coordination, Kimand Chung [27] presented a framework to support design andmanufacturing process collaboration using web ontology andweb services.

To the authors’ knowledge there has been no reported re-search in the application of web-service-based SOA to FD andanalysis. Therefore, the main object of this research is to estab-lish a web-service-based SOA based platform to support the ap-plication of collaborative FD and analysis. Such a system wouldrequire an efficient information support and sharing method-ology for designing a fixture[28]. Mervyn et al. [29] tried topropose an information model of FD in an integrated productand process development environment, but they failed to cap-ture the information for fixture analysis. Thus, it is necessary toperform more studies on information model for process devel-opment in FD and analysis.

III. SYSTEM ARCHITECTURE

The developed IFDA system addresses collaborative FD anduses a web service based SOA approach. Its overall architectureis shown in Fig. 1. IFDA is designed as a distributed systemwith a three-tier structure. It consists of a presentation layer thatprovides thin-client user interface to various users including de-signers and analysts, an application layer that performs func-tional services for engineering processes, and a resource layerthat maintains the storage of FD and analysis data.


Fig. 8. An FD process. (a) The workpiece is imported into the system. (b) A surface is selected to face to the working face of a baseplate. (c) A baseplate can bechosen from the filtered list. (d) Two surfaces are selected for locating with guide of the maximum locators’ distance rule. (e) Two locators are loaded with the ruleused. (f) Final FD.

A. Presentation Layer

This is a swing user interface using Java3D Canvas for FDand analysis. Each client has a web service client called “clientgateway” that is interfaced to “server gateway” on the serverside. This enables the users to access the system services to per-form FD and analysis. The gateways maintain the user sessionand dynamically invoke the functional services from the server.

B. Application Layer

Functional services and business logic represent the appli-cation layer. The business modules include server gateway,core engine, project manager, geometry modeling, FD processmodule, analysis module, and model compression.

Server gateway includes the service endpoints that expose thefunctions for the end user and is responsible for communication

and message passing between the server and clients. The coreengine has a service handler, a controller and a component in-terface handler. The service handler handles all requests and re-sponses from and to the user. The controller is responsible fordelegating a user request and the component interface handlerintegrates the different modules with the main system.

Project Manager Module manages the user and sessions.Project structure management and user management arecommon processes for creating a project, adding a user,deleting a user, creating a group, joining into the project,etc. Session management mainly includes three operations:Create-session that starts a new session for one user in thecollaborative design; Kill-session that closes the opened sessionafter finishing a related design; Join-session that allows thecurrent user to join in an existing session for co-visualization.


Fig. 9. Rule for baseplate selection filtering.

Mating engine algorithms handle assembling fixture ele-ments with the machining parts. The rules are managed by arule engine which is implemented with JBoss Rules [30], anopen source and standards-based business rules engine. JBossRules is employed in the deployment as it adds flexibility to theSOA implementation.

The analysis process module generates the configurationXML file for FEM preprocessing and retrieves the feedbackfrom FEM postprocessing. FD module is responsible for fixtureprocesses and functions. Geometric modeling module connectsto Open Cascade (OCC) solid modeling kernel and providesnot only essential CAD query and manipulating functions for aFD process, but also Constructive Solid Geometry (CSG) andfeature-based modeling capabilities.

In order to improve system performance and reduce trans-mission time, facet visualization data are compressed using theEdgebreaker algorithm [31] that provides a compact represen-tation for the visualization of the CAD model. The authors haveexplained the detailed implementation of this algorithm for datacompression in [32].

C. Resource Layer

Resource layer consists of the database, rule base, file repos-itories, geometric service, and analysis service. The databaseholds user details, project information and session managementdata using MySQL. There are three repositories viz., STEP filerepository, IFDA file repository and fixture element library.STEP file repository holds all the STEP files designed by theuser. The IFDA file is a XML structured application file forfixture configuration and the fixture element library stores thevarious fixture elements [33] used for designing a fixture. Therule base contains various rules for designing a fixture.

In the developed system, the OCC solid modeling kernel hasbeen utilized to carry out the manipulation of product modelsfrom geometry modeling module at the application layer. SinceOCC kernel is written in C++ language, OCC wrapper is neededto utilize the modeling functions. Java Native Interface (JNI) al-lows Java application running in the Java virtual machine (JVM)to operate with application or libraries written in different lan-guages. Thus, JNI is employed for OCC wrapping and geo-metric modeling at the application layer.

Analysis service is responsible for the design analysis toperform preprocessing, solving and postprocessing using FEM.MSC.Patran is utilized for preprocessing and postprocessingand MSC.Marc for solving. The Patran commands are wrapped

Fig. 10. FD data file in XML schema.

through C language, thus similar to the OCC kernel and theanalysis module can carry out the operation of FEM via thisanalysis wrapper.

IV. FIXTURE DESIGN (FD) PROCESS

In this work, the FD is a sequential workflow that consists offollowing tasks: importing workpiece, baseplate selection, de-termining the locating, supporting, and clamping elements andsaving the configuration. Fig. 2 shows the sequential workflowof the interactive FD. Solid lines represent the interaction be-tween processes, and dashed lines show the interaction betweenthe various processes and the client gateway. The procedure fordesigning a fixture is explained in detail in [9]. Each processinteracts with a unified interface, the client gateway, to commu-nicate with services at the server side. Since saving a design isindependent with other tasks, it is not shown in Fig. 2. One ofthe key features of SOA development is that the business pro-cesses are transparent. That is, when a user is operating with theFD process, he/she does not know where the services come fromand only interacts with the user interface to complete the job.

The diagram in Fig. 3 shows the interaction sequence amongthe components in IFDA during a FD process. When a userrequests for a FD process, e.g., loading a baseplate, the clientgateway requests for the baseplate service and sends in the re-quired input parameters like, the type and size of the baseplateto be loaded. Once the functional web service gets the request, itdelegates the request to the FD component. With the necessary


Fig. 11. User interface for generating boundary conditions.

input details, the baseplate STEP file is retrieved from the repos-itory and then generates TopoDS objects via the OCC kernel. Atessellated mesh of the model is created by invoking a functionalcall on the OCC kernel. The meshed data are then formattedand compressed with the model compression (MC) module. Thecompressed mesh data are encapsulated into a XML file, and itis then sent to the client.

Received by the client gateway, the XML file is parsed andthen decompressed. The mesh data are then rendered in Java3Dcanvas for user visualization and manipulation. This process isrepeated until all the necessary elements are loaded and the de-sign of a fixture is completed.

V. FIXTURE DESIGN (FD) INFORMATION EXCHANGE MODEL

The information exchange between FD and fixture analysisis made possible through the FD file, boundary condition fileand the result file in XML schema. The FD data file contains in-formation about the workpiece and the fixture elements and theorientation of the fixture elements in the , , and directionwith respect to the workpiece. The boundary condition file con-tains the details of boundary conditions to be applied to the FDfor analysis. The boundary conditions for the FD contain param-eters such as clamping pressures, cutter tool path file name andmaterial properties for fixture elements. All these data are used

for automating the preprocessing tasks within FEM. The resultfile contains data from FEA results for fixture analysis. Thesedata returned to designers can help them to evaluate the qualityof the designed fixture.

However, before representing data using XML, a documenttype definition (DTD) [29] has to be specified. This wouldgovern the data structure contained by the XML file. The struc-ture of the DTD of each of the developed information model isshown in Figs. 4–6.

The DTD for FD configuration in XML schema is shown inFig. 4. It is made up of information on the workpiece and thefixture elements such as clamps, locators and the supporting el-ements. Each of the main attributes has sub-attributes, whichclassify the main attribute further. For example, the workpieceinformation attribute has two subattributes, which are work-piece ID and workpiece orientation. The workpiece ID describesthe identity of the workpiece whereas the workpiece orienta-tion describes the orientation of the workpiece on the baseplate.Similarly, the locating, supporting and clamping elements con-tain information on the identity of fixture elements and theirorientations.

Fig. 5 defines the DTD for applying boundary conditions. Itcontains information such as material properties of the work-piece and fixture elements, machining tool path data, clamping


Fig. 12. A boundary condition file for fixture analysis.

pressures, and FD data file specifications. This information isused for automating the preprocessing tasks in a FEM process.The DTD for representing FD performance is shown in Fig. 6.It contains information such as the machined element deforma-tion, locator reaction forces, maximum stresses developed, etc.This information serves as feedback to verify the quality of thedesigned fixture.

VI. FIXTURE ANALYSIS PROCESS

This section describes the various stages involved in fix-ture analysis and the fixture analysis process in an IFDAenvironment.

A. Steps in Fixture Analysis

In the final phase, IFDA will use FEM to analyze the modelunder the simulation of external forces due to machining of thework piece. A key fixture analysis requirement is to predict theminimum reaction forces at the fixture contacts under the ex-ternal cutting forces and moments. This will facilitate the de-signer to analyze and ensure that the designed fixtures are able toperform their task under a given manufacturing condition. Thus,Fixture analysis serves as a feedback to study the feasibility andthe performance of a given FD.

Fixture and workpiece contact is modeled as deformable ele-ments interacting with each other with friction. The machiningprocess is simulated using the cutter tool path. The workpieceboundary condition is defined by locators and clamps and theclamping force is considered as an external load.

The various steps involved in the analysis are preprocessing,solving and postprocessing

1) Preprocessing: Preprocessing tasks are used to define afinite element model. A key element in preprocessing a fixtureelement model is contact analysis. Since a fixture model con-sists of several bodies (e.g., clamps, locators, etc.) in contactwith the workpiece, defining a proper relationship model be-tween these different bodies is necessary. This ensures that thefixture elements are in contact with the workpiece without anypenetration or separation before the machining commences. Thewhole model is then meshed and boundary conditions such asclamping force, material properties, etc., are applied. The outputfrom the preprocessing file is a Finite element data file which isstored in the server database.

2) Solving: The next step is to solve the model on a FEAsolver. The FEA solver generates a result which is stored in thedatabase for postprocessing.

3) Postprocessing and Report Generation: After the solvergenerates the result file, the various reaction forces, displace-ment of the workpiece is plotted and stored in the database asa report. This report file helps the fixture designer to judge thequality of the design.

B. Fixture Analysis in an IFDA Environment

To integrate FD with analysis, the client gateway on the clientside is provided with a user interface with which the client inter-acts with the FEM module. Commercial FEA software MSC.Pa-tran and MSC.Marc have been used for fixture analysis. Patran


Fig. 13. User interface for generating input deck for FEM process.

command language (PCL) is utilized to automate a fixture anal-ysis process on the server side. The interaction of the client withthe fixture analysis is described in detail in the case study.

Fig. 7 gives a summary of the fixture analysis process in anIFDA environment. It can be seen that once there is a user re-quest for fixture analysis, the client gateway requests for thefixture analysis service and sends in the required input parame-ters like the STEP file, IFD file (FD configuration file in XMLschema) and the FBC file (boundary condition file for fixtureanalysis in XML schema). The IFD and FBC files in conjunc-tion with the FD STEP file serve as an input for automating theFEM procedures such as preprocessing, solving and report gen-eration tasks.

Once the functional web service gets the request, it delegatesthe request to the analysis component. With the necessary inputdetails, the analysis component generates the batch and the ses-sion files (used for automating the preprocessing and the solvingtasks) and also retrieves the FD files (STEP + IFD + FBC) fromthe repository. A functional call for executing the batch file isthen given by the analysis component and the analysis procedurestarts. The status file generated by FEM is encapsulated into anXML and sent to the client. Received by the client gateway, theXML is then parsed and decompressed to display the status file.

VII. CASE STUDY

In this section, a case study showing how the developed plat-form can be used for FD and analysis is illustrated. The work-piece presented in Fig. 8(a) is taken for FD and analysis. FDneeds to be done for machining the slots on the workpiece high-lighted in Fig. 8(a).

The procedure for FD commences by loading a baseplate.Note that the fixture elements are chosen from the commercialfixture element library. In addition to supporting the workpiece,the baseplate also positions the clamps and locators which areused to restrain the motion of workpiece. The designer can firstselect the surface(s) [highlighted in Fig. 8(b)] whose normal(s)is/are opposite to the normal of the baseplate’s work surface. Bycalculating the total area of the selected surfaces, the candidatebaseplates for selection [Fig. 8(c)] are filtered by a rule which isimplemented in the system using JBoss Rules. An example ruleimplemented in rule base is shown in Fig. 9, which indicates thatthe area of the baseplate must be greater than 1.5 times the totalarea of the selected surfaces. The workpiece is then located byloading the locators on the baseplate. The position of the loca-tors and the clamps on the baseplate can be done with the help offixturing rules available within IFDA or manually by selecting abase point on the baseplate. For example, the locators are placed


Fig. 14. User interface for viewing result and status files.

on the baseplate using the maximum distance rule, as shown inFig. 8(d). This ensures that the distance between the two loca-tors is maximized to ensure greater stability. The result of usingthis rule is shown in Fig. 8(e). The locator/clamp can also be po-sitioned on the baseplate by selecting a point on the baseplate.Similar procedure is followed for positioning the clamps to se-cure the workpiece. The final FD configuration designed usingthe developed system is shown in Fig. 8(f). The output from theFD process is a geometry model file (in STEP format) and aFD configuration file which are stored by the fixture designer inthe server repository. The fixture design configuration file (IFD)generated by the system in the XML format is shown in Fig. 10.

After the FD process is complete, the user can start to analyzethe fixture. The process of fixture analysis can be divided intothree steps:

A. Step 1: Generation of the Boundary Condition File

The analyst uses the IFDA client (Fig. 11) to input FD datafile, machining data file, which has the cutter centre location,assigns material properties to workpiece and fixture elementsand specifies the clamping forces. These parameters form theboundary conditions for the FEA process. The machining datafile contains details of the cutter geometry, feed rates, and cuttertool path for machining. The cutter motion then determines thefinite elements to be removed during the machining process in

order to simulate the actual machining. A sample of boundarycondition file (FBC) in XML format is shown in Fig. 12. Thedetails of the file are explained as follows:

• Specification of FD data file specification – The user spec-ifies the FD data file (IFDA file) which is created after theFD has been finalized.

• Specification of material properties and clamping pres-sures – Here, the user specifies the material propertiessuch as the material type, Young’s Modulus, Poisson ratio,and density for the locating and clamping elements andalso for the workpiece. Note that the baseplate is modeledas a rigid body; hence no material property specificationis required for the baseplate. For clamping elements,clamping pressures are specified as well.

• Machining file specification – The machining data file pro-vided by the user also forms a part of the boundary condi-tion file since it describes the machining features on theworkpiece.

B. Step 2: Generating the Input Deck for the Solver

After generating the FBC file, the designer now has all theinput files (STEP + IFD + FBC) necessary to generate the inputdata for performing the analysis at the server side. This is doneby clicking on the “Analysis input” tab, as shown in Fig. 13.After the user clicks on the “Generate” button, the input deck


Fig. 15. Status file viewed via the web browser.

files for solving, including the batch and session files, are cre-ated in real-time. The batch file in conjunction with the ses-sion file automates the preprocessing and the solving tasks suchas applying boundary conditions, generating mesh, creating theinput data file for the solver, and sending the job to the solver.As stated before, PCL has been used for automating the FEMprocesses. The analysis process begins when the user runs thebatch file by clicking on the “Apply” button under the “AnalysisInput” tab. In order to handle multiple requests from users foranalysis, a meta-scheduler has been designed [32]. The meta-scheduler helps in resource discovery and optimal utilization ofresources for running multiple jobs. However, its discussion isbeyond the scope of this paper and its design and implementa-tion can be found by referring to [32].

C. Step 3: Checking the Job Status and Viewing the Results

The user can check the status of the job through the “Analysisoutput” tab, as shown in Fig. 14. It contains a list of job beingcurrently run on the server and their status (.sts file). An exampleof status file (“Punch_Casing_Nikhil_11:52.sts”) is shown inFig. 15. Once the analysis job is completed, a report file willbe automatically generated with automatic report generation al-gorithm using PCL. The result file reports the locator reaction

forces, maximum stresses generated, workpiece deformation,fixture element displacement, etc. As a part of the result filegenerated, Fig. 16(a) shows the deformation profile, while ma-chining and Fig. 16(b) illustrates the fixture element reactionforces when the cutter traverses through its path. All the infor-mation helps to determine the quality of the fixture designed.The fixture designer then evaluates the FD and the process isreiterated if the fixture requires redesigning or modifications.

VIII. CONCLUSION

This paper presents the design and implementation of a FDand analysis system based on the service-oriented architecture.This enables designers across the globe to collaborate seam-lessly in arriving at a design. The benefits of using web-ser-vice-based SOA for a collaborative FD and analysis system areinteroperability, platform-independence and language neutralityof web services and SOA. The developed IFDA system bringsabout the following benefits:

• It can make full use of expertise in the interactive FDsystem guiding novice fixture designers in arrival at a FD;and at the same time provide flexibility for expert designersto design more complicated fixtures.


Fig. 16. Result file viewed via the web browser. (a) The deformation profile as cutting along the slot. (b) The fixture element reaction forces when the cuttertraverses through its path.

• The information models were developed using the XMLschema to facilitate exchange of information between FDand analysis. This enables integration of two different do-mains, namely design and manufacturing, seamlessly andprovides a dynamic and efficient environment for informa-tion exchange.

• SOA enables small to medium sized enterprises to collab-oratively design fixtures, which reduces the product leadtime and makes the design and manufacturing processmore cost-effective.

In the developed system, the collaboration between FD andfixture analysis is made through information exchange withXML format in two folds:

• Forward: after the interactive FD process is completed, thefixture design configuration file (IFD) created is used in thefixture analysis process to generate the boundary conditionfile for fixture analysis.

• Feedback: after the fixture analysis job is completed, a re-port file is generated from the analysis results. This re-port helps the designer to evaluate the quality of the fixturedesigned.

However, the automatic analysis procedures are limited toprismatic parts only. Further work needs to be done so that thePCL codes for automatic analysis procedures can be made morerobust for handling complex parts and assemblies.

APPENDIX

CAD Computer Aided Design.

CORBA Common Object Requesting BrokerArchitecture.

CSG Constructive Solid Geometry.

DCOM Distributed Component Object Model.

DTD Document Type Definition.

FBC Fixture Boundary Condition File.

FD Fixture Design.

FEA Finite-Element Analysis.

HTML HyperText Markup Language File.

IFD Integrated Fixture Design File.

IFDA Integrated fixture and design analysis file

J2EE Java 2 Platform, Enterprise Edition.

JNI Java Native Interface.

JVM Java Virtual Machine.

MC Model Compression.

OCC Open Cascade.

PCL Patran Command Language.

RMI Remote Method Invocation.

SOA Service Oriented Architecture.

SOAP Simple Object Access Protocol

SQL Structured Query Language

STEP Standard for the Exchange of Product ModelData.

Sts Status File.

TopoDS Topology Descriptor.

UDDI Universal Description, Discovery, andIntegration Specification.

WSDL Web Service Description Language.

WWW World Wide Web.

XML Extensible Markup Language.

REFERENCES

[1] A. Y. C. Nee, K. Whybrew, and A. K. Senthil, Advanced Fixture Designfor FMS. Berlin, Germany: Springer-Verlag, 1995.


[2] Z. M. Bi and W. J. Zhang, “Flexible fixture design and automation:Review, issues and future directions,” Int. J. Prod. Res., vol. 39, pp.2867–2894, 2001.

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[4] D. M. Pelinescu and M. Y. Wang, “Multi-objective optimal fixturelayout design,” Robot. Comput.-Integr. Manuf., vol. 18, no. 5–6, pp.365–372, 2002.

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[9] F. Mervyn, A. S. Kumar, S. H. Bok, and A. Y. C. Nee, “Development ofan Internet-enabled interactive fixture design system,” Computer-AidedDesign, vol. 35, no. 10, pp. 945–957, 2003.

[10] CollabCAD: National Informatics Centre CollabCAD, 2004 [Online].Available: http://www.collabcad.com

[11] L. Qiang, Y. F. Zhang, and A. Y. C. Nee, “A distributive and collabo-rative concurrent product design system through the WWW/Internet,”Int. J. Advanced Manuf. Technol., vol. 17, no. 5, pp. 315–22, 2001.

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[17] X. Liu, “CFACA: Component framework for feature-based designand process planning,” Computer-Aided Design, vol. 32, no. 7, pp.397–408, 2000.

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[19] S. H. Kong, S. D. Noh, Y. G. Han, G. Kim, and K. I. Lee, “Internet-based collaboration system: Press-die design process for automobilemanufacturer,” Int. J. Advanced Manuf. Technol., vol. 20, no. 9, pp.701–708, 2002.

[20] M. Bachlaus, M. Tiwari, S. Kumar, A. Nassehi, and S. Newman, “Webbased multi agent platform for collaborative manufacturing,” DigitalEnterprise Technol., pp. 325–332, 2007.

[21] Web Services Activity, W3C. [Online]. Available: http://www.w3.org/2002/ws/

[22] WebSphere Software. [Online]. Available: http://www-01.ibm.com/software/websphere/

[23] Microsoft BizTalk Server. [Online]. Available: http://www.microsoft.com/biztalk/en/us/default.aspx

[24] W. Shen, Y. Li, Q. Hao, S. Wang, and H. Ghenniwa, “Implementingcollaborative manufacturing with intelligent web services,” in Proc. 5thInt. Conf. Comput. Inf. Technol. (CIT), 2005, pp. 1063–1069.

[25] W. Shen, Q. Hao, S. Wang, Y. Li, and H. Ghenniwa, “An agent-basedservice-oriented integration architecture for collaborative intelligentmanufacturing,” Robot. Comput.-Integr. Manuf., vol. 23, no. 3, pp.315–325, 2007.

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[28] S. Pehlivan and J. D. Summers, “A review of computer-aided fixturedesign with respect to information support requirements,” Int. J. Prod.Res., vol. 46, no. 4, pp. 929–947, 2008.

[29] F. Mervyn, A. S. Kumar, and A. Y. C. Nee, “Fixture design informationsupport for integrated design and manufacturing,” Int. J. Prod. Res.,vol. 44, no. 11, pp. 2205–2219, 2006.

[30] [Online]. Available: http://www.jboss.com/products/rules[31] J. Rossignac, “Edgebreaker: Connectivity compression for triangle

meshes,” IEEE Trans. Visual. Comput. Graphics, vol. 5, pp. 47–61,Jan.–Mar. 1999.

[32] L. Q. Fan, A. S. Kumar, B. N. Jagdish, and S. H. Bok, “Developmentof a distributed collaborative design framework within peer-to-peer en-vironment,” Comput.-Aided Design, vol. 40, no. 9, pp. 891–904, 2008.

[33] IMAO CORPORATION. [Online]. Available: http://www.imao.biz/

Liqing Fan, Liqing FAN received B.S. degree fromShanghai Jiao Tong University, China, in 1995,and M.Eng. degree from National University ofSingapore (NUS), Singapore, in 2003 respectively.He was a Research Fellow at Laboratory of Cur-rent Engineering & Logistics (LCEL), NUS, untilJune 2009. His research interests have focused onapplications of artificial intelligence techniques inmanufacturing, collaborative computer-aided designand fixture design.

B. N. Jagdish received the B.E. degree in produc-tion engineering from the University of Mumbai,Mumbai, India, in 1998, the M.S.C. degree incomputer integrated design and manufacturing andthe Ph.D. degree in air bearing optimization fromthe University of Huddersfield, Huddersfield, U.K.,in 2000 and 2005, respectively.

He is also a reviewer of the Computers in In-dustry and the Computer Aided Design journals.His research interests include collaborative fixturedesign and analysis, modeling and optimization of

air bearings, and spine modeling for clinical applications.

A. Senthil Kumar is an Associate Professor of Me-chanical Engineering at the National University ofSingapore. His research interest is in computer ap-plications to fixture design and planning, intelligentand distributed manufacturing systems, and micro/nano manufacturing. He has published 2 books andover 150 papers in refereed International Journals andConferences.

Prof. Kumar is a member of ASME and SME. Heis a recipient of the Serope Kalpakjian’s OutstandingYoung Manufacturing Engineers Award (2002) and

the IES Prestigious Engineering Achievement Award (2004).

S. Anbuselvan received the B.E. degree in mechan-ical engineering from Bharathiyar University, Coim-batore Institute of Technology (CIT), India, in 1998.

His research interests include collaborative fixturedesign and analysis, simulation and visualizationtechnologies.

Shung-Hwee Bok, photograph and biography not available at the time ofpublication.

Documents

Collaborative Fixture Design and Analysis Using Service Oriented Architecture