An intelligent computer aided instruction system for plant operators to study emergency procedures

Symbiosis of Human and Artifact Y. Anzai, K. Ogawa and H. Mori (Editors) © 1995 Elsevier Science B.V. All rights reserved.

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An Intelligent C o m p u t e r Aided Instruction S y s t e m for Plant Operators to Study E m e r g e n c y

Procedures

Hiroshi UJITA Power & Industrial Systems R & D Division, Hitachi, Ltd. Omika 7-2-1, Hitachi, Ibaraki, 319-12 JAPAN Tel: 81-294-53-3111 Fax: 81-294-53-9583 E-mail: ujita @ erl. hitachi, co. jp Takeshi YOKOTA Hitachi Research Laboratory, Hitachi, Ltd. Naoshi TANIKAWA Hitachi Works, Hitachi, Ltd.

ABSTRACT Intelligent CAI system has been developed which makes it possible to provide consistent education in plant operation and also plant behavior for professionals like shift supervisors. Satisfaction of intrinsic motivation was tried by representing instruction according to the learners' level. The student model, which is common to teaching course for presenting text knowledge of emergency procedures and the indicating course for actual plant behavior and procedures using the plant simulator, was derived from a hierarchical function model which is a goal oriented mental model of a plant operator. The understanding level of each node (element of a function) in the model is evaluated by personal history conditions calculated from both the tutoring record of the node and the understanding level of the connecting nodes.

1.INTRODUCTION In order to perfonn appropriate operations during a severe condition, operators need both skill- and rule-based training and knowledge-based training. A full scope simulator has been used for skill- and rule-based training. But, knowledge-based training has been done by reading textbooks. It is difficult for operators to master the technical background to the emergency procedures and the behavior of plant parameters only by reading about them, because emergency procedures are set based on many analyses of plant behavior under severe

1014 and complicated conditions. The main objective of an intelligent computer aided instruction (CAI) system is to provide operators with knowledge of procedures and also plant behavior [Yokota, 1992&1993]. 2.SYSTEM CONFIGURATION The system configuration is the same as the usual Intelligent CAI system as shown in Fig.l, except it is attached to a simulator which assists in creating plant behavior and actual procedures to respond to the behavior. The system is designed with four study steps, so that learner- users can study the emergency procedures step-by-step from an elementary level. (1) The general concepts of plant safety and emergency procedures are explained. (2) The technical background and contents of the emergency procedures are explained, and the understanding level is confirmed in a Question & Answer style study after that. (3) Real time simulation is executed for a certain accident scenario to instruct the behavior of the main plant parameters. Operation of main plant components and devices (e. g. valves) can be performed by answering questions which are asked from the system according to the plant status, and learner- users can achieve the ideal operation as a result. (4) Students can use any scenario, as in the fourth step, and can achieve the operation by themselves. They can compare the change of parameters from their own operation with the ideal one, and can recognize the necessity of the operation quantitatively. Through the above steps, learner - users come to understand the technical background of the emergency procedures and the behavior of the main plant parameters. 3.TUTORING FUNCTION The system is designed to satisfy the following four tutoring functions: (a) individual tutoring adaptive to student understanding conditions; (b) conversation between students and the system by mutual initiative; (c) harmonization of knowledge of procedures to that of plant behavior; and (d) promotion of a goal-oriented policy to respond to plant symptoms. The first two functions are characteristics of an intelligent tutoring method, and the latter two are requirements for education in emergency operation procedure. The student model and tutoring strategy using it have been proposed to realize these functions as shown in Fig.2. Main characteristics of the system are as follows. (1) The system has two types of broad tutoring courses teaching text knowledge by using a Question & Answer style (first and second steps), and teaching actual procedures and process behavior by using a simulator (third and fourth steps).

The tutoring strategy selects the

appropriate step from among the four and instructs operators according to their understanding levels as evaluated from the individual's educational history and error content in the student model, which is common to both courses. (2) The student model is defined as a combined structure of the hierarchical function model

1015 [Rusmussen, 1983], which is considered as the plant operator's goal oriented mental model, and the detailed flow chart of operation procedures via a function concept. The educational history and the understanding level are assigned on each element of the structure. The model is commonly used for each step. (3) The understanding level of each node (element) is evaluated by personal history conditions calculated from both the tutoring record of the node, which is composed of the number of correct answers and newest error type, and the understanding levels of the connecting nodes. This function helps students to recognize their understanding level and allows them to concentrate on weak points. 4.SIMULATOR The simulator is used for the purpose of educating learner - users in emergency procedure operations. So, it is designed to be able to simulate plant situations, including accidents in which symptom-based plant operation is applied. The plant status can be indicated and the operation can be performed in real time as shown in Fig.3. 5.VERIFICATION Functional evaluation of student model and tutoring strategy (determination) function were done using seven subjects; two novices, three experts, and two professionals. The subjects studied four main procedures each for one hour using knowledge education course.

The

understanding levels, and recommended courses and areas were shown to them and interviewed afterwards. The result of the novice, as examples, shows understanding level is low (mean level = 35) all over the functions. The high levels points arc confirmed by him because of correctness due to the randomness. On the other hand, expert's result shows high understanding level (mean level = 71) and low in sub-criticality functions. Component level understanding is a little bit low compared with conceptual level, which is confinned by him who study knowledge well but not learn detailed operation procedures.

Evaluation results indicated that student model

estimated proper understanding level and tutoring strategy (determination) function recommended proper course and area. Understanding level distribution on the hierarchical function m(xtel was evaluated as shown in Fig.4. As the nodes connected by the arcs have tight functional relationships on the model, little differences among nodes connected each other means good (ideal) balance of studying situation (understanding level). Therefore, vertical axis indicates summation of differences of understanding among nodes and horizontal axis, summation of understanding level of all nodes.

Lower right hand side means ideal understanding level.

Generally speaking,

understanding level points distribute from initial lower left (0,0), increasing, decreasing, and then lower fight of final ideal understanding level (1400, 0). Each subject understanding level distributes on the predicted curve form. It is clear from the graph that learner C understands

1016 each knowledge well but such knowledge is not systematic compared with other experts D and E. 6. CONCLUSION Intelligent CAI system has been developed which makes it possible to provide consistent education in plant operation and also plant behavior for professionals like shift supervisors. Satisfaction of intrinsic motivation was tried by representing instruction according to the learners' level.; (a) The student model, which is common to teaching course for text knowledge of emergency procedure and indicating course for actual plant behavior and procedures using plant simulator, was derived from a hierarchical function model which is a goal oriented mental model of plant operator. The understanding level of each node (element of function) in the model is evaluated by personal history conditions calculated from both the tutoring record of the node and the understanding level of the connecting nodes. (b) The developed system was evaluated using seven learners of different understanding levels and it was confirmed that the system could successfully determine their understanding levels and recommended proper courses according to them. The system was successfully introduced to training center. ACKNOWLEDGEMENTS The work developing Attractive CAI system was done as the joint research project carried out by Tokyo Electric Power Company and Hitachi, Ltd., and Intelligent one, in house of Hitachi, Ltd. We would like to acknowledge Professors Ri-ichiro Mizoguchi of Osaka University, Setsuko Ohtsuki of Kyushu Institute of Technology, and Yoneo Yano of Tokushima University who provided invaluable advice on the concept of education systems. We also wish to thank the participants for the verification tests from the utility operators, the training instructors and the vendor operators. REFERENCES Yokota, T., et al. (1992)" Development of Intelligent CAI System for Emergency Procedure Guideline. SIG-IES-9202-1.1-10 (in Japanese). Yokota, T., et al. (1993): Evaluation of Functions in Intelligent CAI system for Emergency Procedure Guideline. SIG-IES-9303-6. 31-36 (in Japanese). Rasmussen, J. (1983): Skills, Rules, Knowledge; Signals, Signs, Symbols and Other Distinctions in Human Performance Models. IEEE Trans. on SMC., SMC-1__33(3). 257-266.

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