| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Over the past decade the social environment surrounding system safety has changed rapidly. One of the epochs was that TC65 WG9 and WG10 in IEC, International Electrotechnical Commission, established an international standard, IEC 61508. It is applied to almost all electrical/electronic/programmable electronic safety-related systems irrespective of their applications. It has been already quoted into several national standards or guidelines of UK, USA and Japan, including those for process, aerospace and railway transportation sectors. Many studies have simultaneously and independently been made on control system design under possible device failures, reliable control theory, such as integrity, reliable H-infinity control and passive redundancy. The importance of safety function realized in a control system has been growing for the last several years. One of the reasons is that ISO/IEC Guide 51 adopted newly risk for environment and risk for properties as its scope. It is widely known th
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at there are many cases where safety measures outside a control system are not enough to reduce the risk for environment/properties. Hence reliable control theory has been brought to attention by its contribution to system design according to IEC 61508, which can achieve safety function in a control system.
This research presents a probabilistic safety assessment framework based on the international standard, IEC 61508, for control laws designed especially by reliable control theory. The framework uses Markov techniques summarized in IEC 61165 to take restoration of control devices into consideration. It implies that software such as control laws can become an object of probabilistic safety assessment. It can also clarify and evaluate quantitatively a contribution of reliable control to risk reduction according to IEC 61508. The meaning is important beyond measure. That is, safety performance in control laws can be treated as one of important performances to be taken into consideration in system design. Less
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