Reliable control system design for contribution to international safety standard, IEC 61508

在过去的十年里，围绕系统安全的社会环境发生了快速变化。其中一个时代是国际电工委员会TC65WG9-10制定了国际标准IEC 61508。它适用于几乎所有电气/电子/可编程电子安全相关系统，无论其用途如何。它已经被引用到英国、美国和日本的几个国家标准或指南中，包括流程、航空航天和铁路运输部门的标准或指南。在可能的设备故障下的控制系统设计、可靠性控制理论，如完整性、可靠H_无穷控制和无源冗余度等方面，人们同时独立地进行了许多研究。在过去的几年里，在控制系统中实现安全功能的重要性一直在增长。其中一个原因是ISO/IEC指南51采用了新的环境风险和财产风险作为其范围。众所周知，在很多情况下，控制系统外部的安全措施不足以减少对环境/财产的风险。因此，可靠控制理论因其对符合IEC 61508标准的系统设计的贡献而受到关注，它可以实现控制系统的安全功能。本研究根据国际安全标准IEC 61508，提出了一种专门通过可靠控制设计的控制器的安全完整性分析框架。该框架阐明了可靠控制对降低所需风险的具体贡献，以及根据国际电工委员会61508在系统安全设计中确定的可靠控制的含义。因此，几乎所有可靠的控制都可以纳入国际标准体系。它的意义是不可估量的。

Over the past decade the social environment surrounding system safety has changed rapidly. One of the epochs was that TC65 WG9\10 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 that 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 safety integrity analysis framework for a controller designed especially by reliable control according to the international safety standard, IEC 61508. The presented framework clarifies a concrete contribution of reliable control to required risk reduction and an established meaning of reliable control in system safety design according to IEC 61508. Hence almost all reliable control can be included to the international standard system. The meaning is important beyond measure.