Cost Effectiveness of a Man-Machine System Considering Physical Conditions of an Operator

Tetsushi YUGE
Toshio HARA
Shigeru YANAGI

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A    No.7    pp.1314-1321
Publication Date: 1999/07/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Systems and Control
man-machine system,  cost effectiveness,  physical condition,  MTTF,  

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This paper presents two man-machine reliability models. A system consists of one machine unit, one operator, and one event detecting monitor. The machine unit has three states, normal, abnormal, and failed. The event detecting monitor may fail in two ways. If a machine unit becomes abnormal, the event detecting monitor sends a signal, and the operator takes necessary actions. If the operator fails in the action in the cause of human error, the machine unit goes down. The condition of the operator is classified into two types, good and bad. The time to repair, and the human error rate both depend on the condition of the operator. The MTTF is obtained by using a Markov model and numerical computation. Furthermore, the optimal operating period which minimizes the overall cost is decided by using computer methods. Some numerical examples are shown.