The Concept of the Coordinative Decentralized Control System Architecture: CODA
Hiroo Kanamaru, Morikazu Takegaki · Transactions of the Society of Instrument and Control Engineers · 1991
In this paper, we propose the COordinative Decentralized control system Architecture: CODA, as a fault-tolerant industrial plant control system. The system can be reconfigured to adapt to its conditions and environment by the coordination of its controllers. It consists of symmetycally coupling autonomous controllers, and has neither supervisory controller nor reserved one. These controllers communicate with each other and decide their own functions. In order to make the communicating time short enough to keep a realtime constraints, they communicate and cooperate locally. Hence, the global system must repeat these local cooperations till getting to a coordinating state; we call this behavior the coordinative dynamics. For example, when a controller is broken, normal controllers backup its functions locally and gracefully degradate under overloaded condition. And this changing is influences to far controllers gradually. To gurantee such a coordination, we designed Coordination Protocol as the rules of cooperations among the controllers. This Protocol consists of three function layers; the Primitive Communication Layers, the Distributive Scheduling Layer and the Autonomous Scheduling Layer. Using the Coordination Protocol, it is easy to apply other control systems. We analyzed the ability of this Protocol, and made its prototype to confirm the abilability of this framework.