Hartmut Enderlein Chemnitz University of Technology, Erfenschlager Straße 73, D Chemnitz, Germany

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1 In Eds. Smith M.J., Salvendy G., Harris D. & Koubek R.J. "Usability Evaluation and Interface Design: Cognitive Engineering, Intelligent Agents and Virtual Reality" Lawrence Erlbaum Associates Inc. Publishers London, Mahwah, New Jersey, 2001, WEDIS: A TOOLKIT FOR ADAPTABLE CREATION AND SUPPORT OF WORKSHOP PRODUCTION STRUCTURES Hartmut Enderlein Chemnitz University of Technology, Erfenschlager Straße 73, D Chemnitz, Germany hartmut.enderlein@mb2.tu-chemnitz.de Alexander Nikov Technical University of Sofia, K. Ohridski 8, BG-1000 Sofia, Bulgaria, nikov@tu-sofia.acad.bg Bettina Keil Chemnitz University of Technology, Erfenschlager Straße 73, D Chemnitz, Germany bettina.keil@mb2.tu-chemnitz.de ABSTRACT A conception of a disposition toolkit adaptable to customers, customer orders and users is described. It is based on a novel approach integrating fuzzy logic and neural networks for creating adaptable interaction structures. These structures are optimal according to ergonomic requirements. Based on this approach an intelligent adaptation toolkit can be developed and implemented into the new version of an existing disposition software system for creation and support of workshop production structures. Its advantages are presented and discussed. 1. INTRODUCTION WEDIS is a software system designed to support workshop foremen in their daily dispatching and controlling tasks (Keil, 1998). Principle features of this system are capacity planning, cost accounting and effort feedback and job simulation as such as printing daily workers schedules. WEDIS includes the functions of production planning, of control systems and of dispatching systems. So the foreman is able to handle functions he never had in the past. It can be used in workshop structures like tool making, mechanical engineering and mounting sections, handling single orders or small series (Keil, 1997). An adaptation of WEDIS to different customers, customer orders and users can significantly improve the user s work and reduce its introduction costs. For this purpose an approach and its relevant intelligent toolkit for adaptation of user interface was developed. 2. DESCRIPTION OF WEDIS The functional model of WEDIS is shown on Figure 1. The foreman gets custom orders consisting of assemblies which, in turn, consist of several parts. For each part there is a number of working cycles including mounting the parts to assemblies. The foreman has the task to generate order lists, pieces lists, mounting lists and working cycles. He has to print out all documents, make a daily planning, make sure the daily work and has to feedback the daily actual data. The daily planning can be automated by using the capacity planning tool. The capacity planning process takes into account the workers' skills and the workers and machines availability. The workers fill out the time they need for doing their jobs in their schedules. The foreman collects them at the end of the working day and transfers these data to WEDIS. So an exact cost accounting for each custom order is made. As a result a cost pre-calculation for new, similar orders is possible. Advantage of WEDIS is the integration of the traditionally separated functions parts list, working cycle and daily schedule in one interface. The functional and handling model of WEDIS are interdependent. For defining of a functional model it was necessary to develop the system in a participative way. So could be determined the functions and the handling watched. The handling model was defined by adding events into the functional model and watching on the one hand the user behavior and the other hand the effects on the objects (cf. Figure 2). As first step it was possible to find out typical handlings for the process management and typical reaction in case of disturbances. Workshop foremen are most likely not familiar with computers. The interface of WEDIS was especially designed for supporting users with limited computer skills. So there are three variants of the system. In order to ensure good user interaction with WEDIS the disposition process was splitted into planning processes and daily work. They are 474

2 displayed in different colors. So the user is able to recognize the working level and to concentrate to his tasks and not to system handling. customer offer order order coverage inquiry cost accounting compare with former efforts split into assemblies assemblies split into parts mounting plan parts plan working cycle integrate into process cooperation partners workers check capacities capacity planning machines enable order deliver manufacturing report effort Key cost post-calculation function order archiving data structure order archive Figure 1. WEDIS functional model 3. INTELLIGENT ADAPTATION TOOLKIT (IAT) For adapting WEDIS to the customers, customer orders and users the following approach and relevant toolkit are proposed. 3.1 Approach description For adaptation the recorded logfiles of user dialogue with WEDIS can be used. The interaction points in WEDIS interaction structure should be moved up according to their frequency of use. In this way often-used interaction points are reached through a shorter selection pathway in the newly created interaction structure. 475

3 Figure 2. Find out a handling model For realising this idea the neuro-fuzzy model developed by one of the authors, i.e. the fuzzy backpropagation (FBP) algorithm (Stoeva and Nikov, 2000) is used. It combines fuzzy sets and the adaptable neural networks. The steps of the approach proposed are given in Figure 3. In step 1 experts define the initial interaction structure of WEDIS presented as a tree hierarchy (cf. Figure 3). It consists of two types of interaction points (IP): 1) dialogue functional interaction points which are connected with the function responsible for manipulation of dialogue objects, e.g. windows, menus (cf. IP1, IP2, IP3, IP7); 2) application functional interaction points (AFIP) which are connected with the functions changing the properties of application objects, e. g. files, text documents, (cf. IP4, IP5, IP6, IP8, IP9, IP10, IP11, IP12, IP13). On the basis of the logfile data a matrix of transitions between all AFIP pairs is determined (step 1). In case of a menu structure they represent menu action options. The AFIP weights are trained by a modification of FBP algorithm (step 2). Based on ergonomic constraints the maximal number of arcs starting from a tree node can be determined, e.g. the maximal number of options of a menu (ISO , 1997). By this way the set of AFIP weights is divided into subsets (step 3). Subsequently for each subset an interaction substructure with optimal weighted path length tree is formed (step 4), where the sum of the weighted path lengths is minimal. The remaining interaction substructures are similarly bottom up constructed to form the overall optimal interaction structure (step 5). 476

4 1 Determining of initial interaction structure and of matrix of transitions between each AFIP pair 2 Training of AFIP weights 3 Partition of AFIP weights set to subsets applying ergonomic constraints 4 Minimum weighted path length subtree hierarchy Are there other AFIP weight subsets? Yes No 5 Optimal tree hierarchy Figure 3. Sequence of steps IP 1 IP 2 IP 3 IP 4 IP 5 IP 6 IP 7 IP 8 IP 9 IP 10 IP 11 IP 12 IP 13 Figure 4. Part of the WEDIS interaction structure 477

5 3.2 Intelligent toolkit for the creation of adaptable user interfaces It is planned to implement the approach proposed in the software toolkit IAT. It should be created with help of the software package MATLAB. After successful testing of the approach the created computer program can be exported as a source code in C++. So the final version of the toolkit can work as module of WEDIS or better as stand-alone system interacting via inter-process communication with WEDIS (cf. Figure 5). logfile data WEDIS Intelligent Adaptation Toolkit (IAT) adapted optimal interaction structure Figure 5. Communication between WEDIS and IAT 4. CONCLUSIONS A conception of an intelligent adaptable toolkit based on a novel neuro-fuzzy approach is presented. Together with it WEDIS presents a new powerful intelligent disposition toolkit for creation and support of workshop production structures. It can find wide application in workshop structures such as tool making, mechanical engineering, assembly sections, handling single orders or small series, etc. A new object-oriented version of WEDIS suitable for interface adaptation will be developed. The advantages of IAT proposed are: 1) supporting the acquisition of implicit user s knowledge without representation of knowledge in explicit form, i.e. implicit user modelling which is an advantage in comparison to other user modelling approaches; 2) handling logfile data measured in scales of different type and of missing data; 3) rapid search/access time; 4) reduction of introduction costs and training needs. This approach enables: 1) system defaults for different customer groups; 2) system defaults for specific customer orders; 3) system defaults for different level of user experience; 4) individual user adaptation ensuring better user acceptance, etc. IAT can be applied in many other software systems. Further advantages for WEDIS include: 1) quicker data entering; 2) better user interface by multimedia help system; taking into account recognition aspects and spoken output. REFERENCES ISO "Ergonomic requirements for office work with visual display terminals (VDTs) - Part 14: Menu dialogues", Keil, B. "Auftragssteuerung leichtgemacht Werkstattsteuerung fest im Griff. Betriebstechnik aktuell", 1998, 8, Keil, B. "WEDIS - marktorientiertes Produzieren mit Hilfe angepaßter Systeme für Planung und Steuerung". Proceedings of the Ilmenauer Wirtschaftsforum, Ilmenau, Stoeva, S. and Nikov, A. "A fuzzy backpropagation algorithm", Fuzzy Sets and Systems, 2000, Vol. 112, No. 1,