The Application of Large-Scale Hypermedia Information ... - CiteSeerX

The Application of Large-Scale Hypermedia Information Systems in the Manufacturing Industry W. Hall, R. Crowder∗, I. Heath and R. Bernard∗ Introduction Documentation for a manufacturing system can range from a few hundred pages for a medium sized industrial machine-tool to many thousands of individual manuals together with supporting drawings for a complete manufacturing plant. With this volume of information, and the change to multi-skilling of personnel within many industrial plants, a number of problems with conventional information retrieval can be identified: • Constant cross referencing, between text, engineering drawings and lists can be time consuming and prone to error. • The quality of the documentation, particularly on the shop floor, can be very poor, or incomplete. • There is no guarantee that the latest information at hand is up to date. With a paper based system, the issuing of updates and modification notes may not be rigorously enforced, hence the available documentation may not be the latest version. • Information gleaned by previous users, normally recorded in personal logbooks, needs to be recorded in some form that will allow future access. However it needs to be separated from the main database, but easily accessible. To study the use of hypermedia in the industrial environment, the Multimedia Research Group at the University of Southampton have been working with Pirelli Cables, Aberdare, to develop an information retrieval system specifically for maintenance and operational training using the Microcosm hypermedia system developed at Southampton1. The plant is widely considered to be one of the most advanced CIM facilities within Europe: the rationale for its construction, and the background to its industrial relations policy has been reported elsewhere2. One aspect of its current management practice that needs to be considered in the context of this paper is the flexibility of the labour force, where the operator is permitted to undertake minor fault-finding on the machine, before maintenance is called. In addition the operators are expected to be familiar with a number of processes; this requires the development of several training and familiarisation packages that present operators with a refresher course of a machine functionality and set up parameters prior to moving to a new process activity. ∗

Department of Electrical Engineering

The main product at Aberdare is UK standard three core cable, a large proportion of which is sold in packs containing 100m of cable. In order to pack the cable two identical packaging lines are used; the line firstly erects a carton, while a measured length of cable is wound onto a mandrel. The coil of cable is dropped in to the open carton, then the packaging line assembles the reel round the cable. The final task is to seal, and label the box prior to dispatch. The cable-packing machine, illustrated in Figure 1, is by its very nature complex, with a considerable number of sensors and electromechanical actuators. Due to its complexity the machine is prone to misalignment, and reliability problems, which made it an ideal candidate to prove the concept of hypermedia maintenance resource.

Application development The biggest cost in the implementation of a new hypermedia application is in the authoring. This requires significant effort in several areas, including the collection and formatting of the data, constructing and checking the linkbase, and subsequent maintenance of the application. Collection and formatting of the data is the biggest element and can vary depending on the available source material. At one end of the spectrum the documentation to be used may only be available in a paper form and therefore can not be directly loaded into the application. At the other end of the scale all the documentation may be available in electronic form making the authoring in an open system like Microcosm a quick and easy task. If the source material is largely paper based, we have estimated that up to 80% of the time required to develop a new hypermedia application is taken in converting the information into a suitable format. Once a data set has been selected and collected the information needs to be structured in such a way as to make navigation through the application easy and logical. Highlighted links are then overlaid on the data: in the main these take the form of buttons which are obvious graphical hints showing the user where they can move to in the database. However, in the case of engineering drawings it is considered more efficient to define links to the locations of parts as generic links using the name of the part. This has the added advantage in that the part location can then be accessed wherever the part name is used without any extra authoring effort. Using AutoCAD for the circuit diagrams and engineering drawings allows Microcosm to recognise components as objects rather than as a collection of pixels bounded by a set of rectangular co-ordinates. This ensures that all the links will keep their meanings whenever changes are made without having to re-author all the links on a diagram. We are now moving towards using the DXF format for diagrams and drawings which permits all the advantages of AutoCAD for link creation and maintenance, whilst not requiring a copy of AutoCAD to be available when the application is running. One of the main differences between traditional documentation and hypermedia is the ability to use temporal data such as sound and video. These have to be used carefully as the user can often become frustrated at hav-

Figure 1: The Cable-Packing Machine (3-D Model)

ing to sit through the same data again and again to get to a particular piece of information. We have also developed a 3-D model of the machine as an interface to the information system. The model has been developed using 3-D Studio and has been fully integrated with Microcosm. The same model is used as the interface for each mode of use of the system: operator set-up, maintenance and fault diagnosis. The 3-D interface makes using the system very intuitive even for completely novice users since all they have to do is use a pointing device to select the part of the machine about which they require more information. However, experienced users can by-pass the 3-D interface and go directly to component details or circuit diagrams. The widespread use of this type of system will largely be governed by its acceptance on the shop floor. This needs all aspects of the user interface to be considered. Most of the constraints are centred on finding an acceptable approach which will allow the maintainer to use the hypermedia system within the confines of the machine, and have storage and display capabilities well in excess of the present paper-based system. In particular, the standard interface to systems such as Microcosm is a pointing device which would be inappropriate in this situation. With the availability of powerful pen computers, the delivery of multimedia information to the maintainer on the shop floor is now considered practical.

Knowledge-based hypermedia applied to fault diagnosis An advantage of using an open hypermedia system such as Microcosm is that links can be created or accessed in response to a dynamic process such as a database or rule-based query. We have used this facility to create a computer-assisted fault diagnosis procedure within the hypermedia application. This can be used to support

engineers when real faults occur on the machine and to simulate faults for training purposes. There are two different approaches to combining a knowledge based system (KBS) with hypermedia. The first integrates the KBS with the hypermedia system; the second provides a loose coupling between the KBS and the hypermedia system, communication being by message passing3. Examples of the first approach are Expertext4 and PLANTH5. Their disadvantage is domain dependence; it is not easy to use a system developed for one domain for another domain without making major changes in the program. The Microcosm system is a suitable system for the second approach, since a KBS can be easily integrated into the system by creating a filter which handles the Microcosm/KBS interface. An initial prototype has been built using LPA Prolog as the KBS and is described below. In this application the knowledge base consists of the information that is already in the hypermedia system together with a rule-base of simple facts and rules based on information in the maintenance manual and the advice of experienced engineers. The rule-base is a simple set of facts, with some rules which provide access to those facts. The only interface between LPA Prolog and the calling application is via ASCII strings. LPA Prolog provides an interface to the Windows environment to allow simple user interaction: however, it was easier to use a separate interface builder (Microsoft Visual Basic) to build the user interface as a Microcosm viewer. This user interface can communicate with Prolog through the Microcosm system. The Prolog engine can evaluate clauses and return results to the user interface: these results can then be interpreted and presented to the user. Details of how the Prolog system is implemented are given by Heath et al.6. When the fault finding process is first started, the user interface sends a pre-defined clause which provides the gateway into the rule-base. The result of this is then pre-

sented to the user as a simple form. The user can select any of the possible answers to the question, at which point the Prolog clause associated with that answer is evaluated. This results in another form being displayed, with another set of questions or possibly a list of possible faults. At any point the user can backtrack through the answers they have given, and choose other answers and explore other possibilities. The faults act as a gateway into the Microcosm system. When a list of possible faults is displayed, the user is able to follow links from each fault to related information, perhaps giving the location of sensors which need to be tested to determine if that particular fault is occurring . The user can also be directed on to other question and answer sessions or other documents in the Microcosm system by pressing the “Tell me more” button. Once a fault has been found and corrected, the user presses the “This was the fault” button, which causes the Prolog engine to update the relevant fault’s reference count. Faults can be flagged as either operator or maintainer faults. If a combination of operator and maintainer faults occur, the maintainer faults are hidden and replaced by a single entry telling the operator to call a maintenance engineer. When such an engineer arrives, they can see all the possible faults by informing the system that they are a maintainer.

Discussion The perceived advantages of the use of hypermedia databases as an industrial based information system both for shop floor and training applications include: • the ability to integrate data from a number of applications, with the ability to have controlled access to this data and to ensure its integrity and security. • a ‘user friendly’ interface to the system which permits easy access to the data, and ensures that correct procedures are followed. • the ease of construction of the resource bases and subsequent authoring. • the ability of the user to place additional information and notes into the system, within constraints determined by the system manager. The notes can be retrieved at any time by future users. • the ability to use the same database as the basis for interactive training programmes which can be incorporated into traditional training courses or used for on-the-job training. If this hypermedia approach is to be fully adopted for the delivery of operation and maintenance documentation, the logical extension is to take the delivery system on to the shop floor to supplement the hands-on experience and process monitoring. In this case, the operator will require assistance from the hypermedia system to locate the correct data to investigate a fault. With an interface to a factory based local area network, a large

range of significant possibilities arise. In particular the breakdown maintenance process can be significantly enhanced, both in time and effort, by the implementation of intelligent filters, using information both from the database and from the failed system obtained through the network. A direct result of this approach is that when a fault occurs, the resource base is entered at the appropriate point, which is identified by the intelligent filtering process. Once this is achieved the hypermedia information system becomes an integral part of the computer integrated manufacturing system. This communication linking will allow predictive and preventative maintenance procedures to be optimised by using the same resource base but with a different linking strategy. The advantage of the integration of a hypermedia package with a network cannot be under-emphasised. It will give the user the facility to access remote databases, for example stores records and project management activities, to ensure that problems are solved rapidly, and efficiently. In this paper, we have discussed the use of open hypermedia systems to develop a resource-based approach to the provision of electronic information systems for the support of maintenance operations in a large-scale industrial plant. The advantages of the open system approach are in the maintainability of the resource-base, the automatic generation of links and the consequent reduction in authoring effort, and the ability to integrate the resource base with other application packages and the general computing environment. The case study described has been undergoing a full evaluation at the Pirelli site in Aberdare and initial trials have already clearly demonstrated the advantages of the system.

Acknowledgements The authors acknowledge the EPSRC for funding the work under grant GR/H43038, and Pirelli Cables Aberdare for permission to use their site as the case study.

References 1 H. Davis, W. Hall, I. Heath, G. Hill, and R. Wilkins, “Towards an integrated environment with open hypermedia systems,” in Proceedings of the ACM Conference on Hypertext (ECHT’92, Milan, Italy, December 1992), pp. 181–190, ACM Press, 1992. 2 J. Clark, Human Resources Management and Technical Change. Sage Publications, London, 1993. 3 P. Soper and T. Bench-Capon, “Using hypertext to interface to legal knowledge based systems,” in Proceedings of the DEXA 92 Valencia, Springer-Verla, 1992. 4 R. Rada and J. Barlow, “Expertext: Expert system and hypertext,” in Proceedings of the EXSYS, IITT International, 1989. 5 A. Casson, “Planth: An expertext shell for author and readers of technical documents,” Artificial Intelligence Application Institution, Technical Data Sheet. 6 I. Heath, W. Hall, R. Crowder, M. Pasha, and P. Soper, “Integrating a knowledge base with an open hypermedia system and its application in an industrial environment,” in Proceedings for 3rd International Conference on Information and Knowledge Management CIKM’94 Workshop on Intelligent Hypertext (Nov 29 - Dec 1, 1994, NIST Gaithersburg, Maryland), 1994.