Autonomous Controllability of Hierarchical Decentralized Systems
Reiko J. Tanaka, Seiichi Shin · IEEJ Transactions on Electronics Information and Systems · 1997
This paper aims to evaluate the fault tolerance of hierarchical decentralized systems (HDSs) by autonomous controllability. A HDS consists of a number of identical modules, each of which consists again of a number of identical submodules. Autonomous controllability at level α means that the entire system remains controllable, in spite of failures in arbitrary α submodules. Conversely, if the entire system becomes uncontrollable because of failures in a set of β submodules, this number β of failed submodules manifests the level of fault tolerance. We will thus find such sets of submodules to evaluate fault tolerance. A HDS considered here is built by combination of three basic structures, such as ring-type, chain-type and wheel-type structures. Therefore, the structural information of a HDS is described with the type of interconnections among modules and that for submodules. We will show that the results of evaluation for a HDS are obtained by combination of the results based on the interconnections among modules and the results on those among submodules. Various examples are also shown and it is discussed the fault tolerance of different types of structures.