APPLICATION OF MULTI USER TECHNOLOGY FOR TEAMWORK IN CAD MODELLING. Linas GABRIELAITIS 1

Transcription

1 10 th International Conference on Engineering Graphics BALTGRAF-10 APPLICATION OF MULTI USER TECHNOLOGY FOR TEAMWORK IN CAD MODELLING ABSTRACT Linas GABRIELAITIS 1 This work considers the management of teamwork in CAD modelling of engineering design and construction processes. In teamwork a variety of specialists work together on the development of one compound object, which leads to a constant exchanger of technical information and tracking the modifications performed by other project participants. Other difficulties involve working with elements that are connected to another element already used by other participants. A multi-user technology permits multiple users to navigate and interact in a shared virtual environment that facilitates the modelling process, especially when working on complex construction solution for compound and multi-structured models. KEYWORDS: CAD projects, multi-users technology, project management. INTRODUCTION When teamwork occurs in CAD modelling process, the model and drawing are typically saved in one or several files, which become huge in size for a larger project. As a result, the speed of design process is decreasing, and working with a team on the same project becomes complicated and time consuming. File exchange of model elements is inefficient and might be difficult to apply due to many versions and modifications. Furthermore, failure to effectively locate and manage technical information during a project may result in delays and incorrect decisions. The complexity of engineering design operations and the internal collaboration required across engineering departments are dependent on efficient CAD modelling 1 Dept. of Engineering Graphics, Vilnius Gediminas Technical University, Saulėtekio av. 11, LT Vilnius-40, Lithuania, Linas.Gabrielaitis@fm.vgtu.lt 25

2 processes and on management of technical documents. The documents (including drawings) are costly to produce and hard to track since they are typically only of value as part of a large complex set of documents. The consequences of using the wrong version of a document can be very serious. To control the information flow within the project team a multi-user technology has been developed (Gabrielaitis L. et al. 2005). A multi-user technology has been developed to operate with a complex CAD objects in the same way as an electronic archive system, which is implemented in engineering document management systems (EDM) (Björk, B.C. 2002). It offers the structure of hierarchical linking of technical data and documents. The EDM also offers standards for quality management and quality assurance along with customizing and tracking of technical information. The features of quality system document are adopted by a multi-user technology, including information and data control requirements. 1. FUNCTIONALITY OF ENGINEERING DOCUMENT MANAGEMENT SYSTEMS The main difference between the engineering document management systems (EDM) and a multi-user technology is that EDM operates with a document and its properties, while the multi-user technology operates with the construction element in a CAD model. This section describes principles of engineering document management systems (EDM) (Aspin R. et al. 2001). a) A multi-level hierarchical structure, where documents are cascaded from higher to lower levels. When a version or contents of a document changes at a parent level, it will affect the changes of the children levels. Hence document control should provide change traceability from one level to the other level. b) Horizontal process and document linkages internal collaboration across engineering departments. The flow of documents through the entire design processes is cross-referenced and linked to validate the process quality. c) Linkage between documents and product data. The documents act both as input to the product development processes (most product designs are driven by some kind of specification or requirements document) and output as well. d) Documents have various statuses and versions. As a document is developed, it passes through different product life-cycle stages with specific status, e.g., reviewed, approved, distributed or obsolete. 26

3 In accordance with the above-mentioned classification, document management tools have functions that enable: a) Relationship Functions (Parent/Child relationship for assemblies and parts); b) Version Control Functions (Check In/Check Out), authentication Functions; c) Property Management (Linking properties, updating properties), d) Workspace Management (managing a local copy of CAD files and critical events); external document relationships, Excel spreadsheets, Word docs, PDFs, bitmaps); version Control Functions (Lock, Release). The above-described approach is applied to control the technical information when modelling a complex CAD object with a multiple users group. 2. DESCRIPTION OF A MULTI-USER TECHNOLOGY A multi-user technology permits multiple users to navigate and interact in a shared virtual environment that facilitates the modelling process, especially when working on complex construction solution for compound and multistructured models. This section describes principles of a multi-user technology considering existing technologies that has been previously used to facilitate CAD design. The similarities and differences of a multi-user technology with engineering document management system are also highlighted. The existing technology that has been used to facilitate the design of a complex model is based on an external file reference (X-ref). The basic idea behind the technology is that before the designing of a complex model, a strategy should be developed to split up the model between project partners. The split part is placed in an external file X-reference, which becomes the working place for the project participants. However, X-ref that is inserted into the model can only be reviewed (when X-ref file is open). The link between source file and inserted X-ref is preserved and any modification made in the source file is uploaded into the model. This technology reduces the size of a model, because only the image of object from X-ref file is used in a model. The typical X-ref hierarchy is presented in Fig. 1, where links between model and X-ref files are depicted. 27

4 Fig. 1. Technology based on external file reference (X-ref) The disadvantages of X-ref technology are the following: a) Splitting strategy of a model should be developed beforehand, which requires some experience; b) Splitting of the model is performed manually; c) Experience and special measures required when inserting a X-ref into a model (it can only be done by a participant of the design process); d) Rigid modification management process: a model cannot be modified any time. To change a model, a source X-ref file has to be modified first; e) No control process over the current status of working process and no version control functions. To overcome the difficulties of X-ref technology, a multi-use technology was developed, which offers control over the flow of technical information. A multi-user technology operates with the construction element in a CAD model in the same way as engineering document management systems operate with a document and its properties. The properties and technical data in a multi-user technology are attributed to a construction element or a group of construction elements. A multi-user technology has adopted the above-described functions of document management and transfer them to a construction element. 3. THE PRINCIPLES OF A MULTI-USER TECHNOLOGY With a development of modelling techniques, the documents including drawings are seen as presentation views of underlying information model. This technology is based on a product model (Löwnertz, K. 1998). A product model and relations between the parts of a product model are presented in Fig. 2. In this context, documents (drawing etc.) are just 28

5 filtered views of information from a database containing product model data. Our presented system can then be considered a filter, managing the parameters needed to select appropriate information for a certain document or type of document, and presenting that information in a way suited to the purpose (Fig. 3). The document can then be produced on demand and only the information needed to produce the document will be stored. Even if the product model can be viewed at random, there will still be a need to define documents and to manage them. The documents may be quite different from what we are traditionally used to and use new media including 3D presentation, interactivity and video. However, in order to ensure sufficient and correct information, for example to all members of a construction team, exact views have to be defined, versions have to be controlled, distribution or notification of changes have to be managed (Hajjar D. et al. 2000). Fig. 2. A product model is based on relations between product model parts. Documents are created by filtering information of the model through applications Fig. 3. The process of presenting objects from a product model database can be illustrated as two filters: one for selecting which objects to include and the other for the way of presenting them graphically (projection, scale, detailing) 29

6 4. FUNCTIONALITY OF A MULTI-USER TECHNOLOGY The features of the technology are described below. First, the element can be separated from the model (Figs. 4 and 5) at any time without destroying the actual model and preserving its representative characteristics. Then, it can be modified and retuned back to the model. Referring to the EDM characteristics described in previous section, this feature is implemented through the Relationship Functions (Parent/Child relationship for assemblies and parts), and Version Control Functions (check In/Check Out). The attribution of properties to the construction element and assessment of properties is implemented through Property Management (Linking properties, updating properties). Fig. 4. Project participant borrows an element from the model Moreover, multiple users can work on the same element. For example, several project partners can partially borrow (check out) the same beam in order to connect other beams to the common one (Figs. 6 and 7). This is managed through the Version Control Functions (Lock, Release) and Workspace Management functions 30

7 Fig. 5. Project participant displays element in his working environment Beam checked out partially by User 1 and by User 2 Beam checked out partially by User 1 and by User 2 Fig. 6. User 1 creating the joint between the common checked out beam, and the left beam Fig. 7. User 2 creating the joint between the common checked out beam, and the right beam The shared virtual environment in a multi-user technology has the following features: a) Control over working process, where project partners are informed in real time of a modification done by another partner working on the same model; project partners can borrow (check out) a part of the model (i.e., element), and display only that element; b) Several methods to check out elements. Project partners select the element graphically or use the search tool to find an element according to different criteria. c) Partial check out of element, when the element properties can be viewed and accessed but cannot be modified. The several project 31

8 partners can partially check out the same element in order to connect other elements to the common one (Figs. 6 and 7) above); d) Security. Warning is presented if the selected element has already been borrowed by another participant. Warning is also issued if a model is being modified, while some elements are still checked out. e) Graphical information control over who is working on what. The information is presented on who has each element been cheked out by. The elements checked out by a specific participant can be displayed along with elements checked out by all participants. 5. ESTABLISHING WORK IN A MULTI-USER TECHNOLOGY FOR PARTICIPANTS OF THE DESIGN PROCESS This technology does not demand much additional preparation work or knowledge from a participant of the design process. Basic knowledge of engineering document management (EDM) systems is desired from a project leader. To start a multi-user session, a project leader initiates a new project by defining project number. With this operation a new tree, representing structure of the project documentation, appears in the vault of the technical documentation and the new project is initialized. Next, the designer creates settings that are common for all the project participants: project settings, CAD properties and templates. This includes the defining dimension and layers style, text style and selection of CAD standards. After this, project participants can start their work according to their usual routine. 6. APPLICATION OF A MULTI-USER TECHNOLOGY A multi-user technology was tested during the implementation of a teambased design for the complex oval shape of a steel structure (Fig. 10). It was constructed for a conference hall in Vilnius, Lithuania. The advantage of this technology was in using functionality of partial element check out, which permits to view and access the properties of common element but prohibits any modifications. Two project partners, one working on the upper part of oval steel structure (Fig. 8) and the other working on the lower part of oval steel structure (Fig. 9), partially use the same elements - four legs of steel construction. 32

9 Fig. 8. First project participant designed the four legs and the steel structure for the upper part of the oval Fig. 9. Second participant designed the structure for the lower part of the oval Fig. 10. Final project: Steel structure of lower and upper parts connected together The relationships defined between the common and individual elements make it possible to work with individual elements that are connected to the common elements and use their properties. The four legs of construction on which the lower and upper elements of oval structure were connected, were commonly used by both project participants. After the steel structure of lower and upper parts was connected together, the joining bars between both parts were designed (Fig. 10). 7. CONCLUSIONS For the complex CAD modelling, occurring in engineering design and construction processes, and the effective management of teamwork a multiuser technology was developed. A multi-user technology permits multiple users to navigate and interact in a shared virtual environment, where a construction element in CAD model is operated on self-determined bases. It can be borrowed from CAD model to work with independently while 33

10 preserving representative characteristics of the actual model. It operates with a complex CAD object in the same way as an electronic archive system in engineering document management systems and offers a level of control over information flow within the construction process. The technology was tested during the implementation of a team-based design for the complex oval shape of a steel structure. It was constructed for a conference hall in Vilnius, Lithuania. Observed results indicated that a clear improvement was implemented not only due to transfer automation (CAD elements, technical information) between project partners, but also because of the relationships between the construction elements and technical documents. REFERENCES 1. Aspin, R.; DaDalto, L.; Fernando, T.; Gobbetti, E A Conceptual Framework For Multi-Modal Interactive Virtual Workspaces, Journal of Information Technology in Construction, Vol. 7: Björk, B., C The Impact of Electronic Document Management on Construction Information Management. Proceedings of International Council for Research and Innovation in Building and Construction CIB w78 conference, June, Denmark. 3. Gabrielaitis, L.; Baušys, R A Case Study of Project Document Management in Building Design. 11th Joint CIB International Symposium Advancing Facilities Management and Construction through Innovation. Helsinki/Finland/June Hajjar, D.; AbouRizk, M. S Integrating document management with project and company data, Journal of Computing in Civil Engineering, Vol. 14 (1): Kubicki, S.; Bignon, C.; Halin, G.; Humber, P Assistance to building construction coordination towards a multi-view cooperative platform, Journal of Information Technology in Construction, Vol. 11: Löwnertz, K Change and Exchange Electronic document management in building design. Licentiate thesis. Construction Management and Economics Royal Institute of Technology Stockholm, Sweden. 7. Rezgui, Y., and Debras, P An integrated approach for a model based document production and management, Journal of Information Technology in Construction, Vol. 1: