Kuniaki Matsumoto

A Petri Net-Based Controller for Flexible and Maintainable Sequence Control and its Applications in Factory Automation

A new type of software system for an industrial sequence controller is proposed. In this system, a control program is described with the Petri net-like language named Control-net (C-net). This language improves control software maintainability and flexibility. An efficient C-net interpretation schema for real-time control is presented and an overhead time evaluation model of the proposed schema is developed. Through the model analysis and measurement of the response time of an interpreter on a microcomputer, it is proved that the interpretation schema satisfies the required response time. Finally, a microcomputer based controller named Station Controller (SCR) in which the presented C-net interpreter was installed is described and several applications of this controller to real systems are illustrated.

Development of a Hierarchical Operation Scheduling Model and its' Application to Large Scale Water Supply Systems

Abstract A ‘hierarchical operation scheduling model’ is developed to facilitate stable and economical control of all water supply facilities from one central station. The model is structured on three levels. The function of the first level is to calculate the operation schedule of intake stations. The function of the second level is to calculate the operation schedule of purification plants. On this level the whole service area is divided into several zones, and minimum cost flow in the network among the zones is obtained through a primal-dual method. The function of the third level is to calculate the operation schedule of distribution reservoirs. The concept of a calculation module is introduced, and schedules can be laid out for water transportation systems in each zone by using these calculation modules. The hierarchical model is presently in practical use in a city of with a population of 2, 700, 000.

Development of a Reservoir Control Method with the Aid of Unsteady Flow Dynamics Simulation

Abstract A method of designing a reservoir control system which uses unsteady flow dynamics simulation is described. The effect of water level fluctuation on reservoir control can only be evaluated through analysing unsteady flow dynamics. A numerical analysis approach is chosen because of the difficulty in solving the unsteady flow dynamics equation analytically. A special purpose FORTRAN simulation system named RCSS, i.e. River Control Simulation System, is developed. In this system the numerical analysis program of the unsteady flow dynamics equation is installed. With the aid of RCSS, a new reservoir control method is derived. This method makes it possible to maintain water volume at a desired value. Kalman filters are used to get the closest estimate of water volume due to corruption of water level data by various noises. This newly developed control method has proven effective in reservoir control.

Water Leakage Prediction in Distribution Pipeline Networks Using a Queuing Model

Abstract This paper presents a new method for detecting the quantity of leakage in water distribution networks. The area of a pipe-network is divided into several blocks. Only one inlet into a block is opened; all other inlets in the block are closed by valves. In order to find the quantity of leakage in each block, the inflow quantity through the open inlet is measured. When all faucets in the block are closed, and the inflow is minimized, the inflow quantity is the leakage. A queuing model is developed to estimate the possibility of all faucets in the block being closed. From the simulation results with the queuing model, a chart and a simple equation representing the maximum number of households in the block is proposed. These indicate the probable situation when all of the faucets are closed. However, if it is impossible to estimate the probable situation when all of the faucets in a block are closed, the quantity of leakage can be calculated by subtracting the estimated water consumed in the block from the measured minimum inflow. In this case, several patterns of water consumption (e.g. the bathroom consumption pattern) are added to the above queuing model to estimate the quantity of water used in the block. The simulation using this model results in the chart drawn. Various experiments tried in different sections of an actual pipeline network verified these new leakage detection methods. The result of these experiments indicate that the new mothods can be applied practically.

DEVELOPMENT OF A RESERVOIR CONTROL METHOD WITH THE AID OF UNSTEADY FLOW DYNAMICS SIMULATION

A method of designing a reservoir control system which uses unsteady flow dynamics simulation is described. The effect of water level fluctuation on reservoir control can only be evaluated through analysing unsteady flow dynamics. A numerical analysis approach is chosen because of the difficulty in solving the unsteady flow dynamics equation analytically. A special purpose FORTRAN simulation system named RCSS, i.e. River Control Simulation System, is developed. In this system the numerical analysis program of the unsteady flow dynamics equation is installed. With the aid of RCSS, a new reservoir control method is derived. This method makes it possible to maintain water volume at a desired value. Kalman filters are used to get the closest estimate of water volume due to corruption of water level data by various noises. This newly developed control method has proven effective in reservoir control.