Expandable and fault tolerant computers and communications systems -autonomous decentralized systems

Under the evolutionary situation in market and technology, computers and communications application systems are required to attain not only the online property for non-stop operation during partial expansion, maintenance and at the time of a fault but also the flexibility and timeliness to supply the new products and services. Autonomous decentralized systems (ADS) are proposed for these requirements. In the ADS, each system has its own autonomy to control itself and coordinate among the others. The data field architecture for ADS has been realized, where each system judges the sending and receiving of the data on the basis of the content of the data, and the starting of its execution of the function when all the necessary content data is received. Based on this system architecture, technologies for the on-line property have been developed. Moreover the ADS technologies have been extended to adapt to the rapidly and largely changing situation through the integration of the heterogeneous and autonomous systems without mutually violating their objectives. These technologies have been applied in various fields including information service, factory automation, transportation operation, building facilities management and so on, and their effectiveness has been shown. Some of these technologies have been approved to be de-facto standard in the factory automation system.