Risk-Based Assistive Technologies on Maintenance Planning for Safety-Related System

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K04144
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18030:Design engineering-related
• Research Institution: Kansai University
• Principal Investigator: Inoue Shinji 関西大学, 総合情報学部, 教授 (60432605)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 安全関連系 / 最適保全実施間隔 / プルーフテスト / 確率モデル / 再生過程 / 連続時間マルコフ連鎖 / 最適方策

Outline of Final Research Achievements

As the first step, the probability of occurrence of a hazardous event caused by safety-related systems has been derived based on two types of hazardous event occurrence logics that take into account the characteristics of operating mechanisms of the safety-related systems. Then, the hazardous risk has been formulated by introducing certain cost parameters into this measure and two approaches to formulate total cost including the maintenance cost have been developed. Furthermore, we derived optimal policies that enable us to determine the maintenance interval that minimizes this total cost, depending on the dangerous hazard rate and the magnitude of the risk. Finally, in accordance with IEC 61508, the optimal maintenance (proof-testing) intervals have been actually calculated according to the hazardous risk and safety demand rate to the safety-related systems. And examples of the application of these optimal policies have been also presented.

Free Research Field

社会システム工学関連

Academic Significance and Societal Importance of the Research Achievements

自動車の安全機能など，安全関連系が導入される場面は急激に増えている．安全関連系の機能安全に関する国際基本規格IEC 61508をはじめ，学術界でも安全関連系の定量的な安全性評価技術について活発な議論が行われている．一方，安全関連系の保全に関する議論は必ずしも多くは見られず，本研究課題のように安全関連系に起因する危害事象発生論理や危害リスクに応じながら最適な保全実施間隔を算出する技術は，リスク低減方策の基本であるALARP原則を保全活動で実現するために極めて有用なアプローチであると考える．また，本研究課題の成果を発端に，安全関連系の保全方策に対する議論が国際的に活発化することも期待される．