A method is described for improving cooperation in supervisory control and data acquisition (SCADA) systems that uses multi-agent (MA) intelligent field terminals (IFTs). The MA function of each IFT evaluates the control conditions of the overall system and the conditions of the other IFTs. To shorten the turn-around time for data transfer among IFTs, the conflicts that occur when the data processed by different IFTs is inconsistent or irregular are cooperatively and autonomously resolved by predictive agents incorporated into each IFT. Experimental results showed that this method not only provides adequate control but also reduces the load on the network and the turn-around time when the number of IFTs is less than 30.

We have developed a new method to improve cooperation in concurrent systems for distributed control by using multi-agent (MA) functions. Since field terminals (FTs) work concurrently, cooperation among them is essential to the effectiveness and efficiency of the overall system. When FTs are modeled as agents, it is easy to explicitly deal with the interactions among them because those interactions can be modeled naturally as communication among agents with cooperation and negotiation. In conventional central control systems, the host computer supervises and controls all FTs in accordance with a pre-installed control algorithm. Our method instead uses intelligent field terminals (IFTs) that can evaluate the diverse information from devices of other IFTs autonomously. In the work reported here, we have evaluated the effectiveness and efficiency of our cooperative control method experimentally and have developed a system using this method to control various kinds of water delivery systems. The IFT providing MA functions that can evaluate the control parameters (CPs) and conditions of the other IFTs. If turn-around time is to be shortened, the conflicts that occur when the data processed by different IFTs is inconsistent or irregular must be resolved autonomously. Each IFT therefore cooperates with diverse functional agents (FA)s of other IFTs by using priority levels, conditions, and evaluation points in order to maintain the continuity of water delivery.