A PARALLEL DISCRETE EVENT SIMULATION METHODOLOGY OF DISTRIBUTED CONTROL SYSTEMS USING OBJECT-ORIENTED PROTOCOL MODEL AND TIME WARP MECHANISM

摘要

Recently, distributed control systems (DCS) consisting of many devices and an open network interconnecting them, are used in many automation areas. For assuring the control performance under heavy communication traffic, the accurate DCS simulation is strongly needed. For this purpose, we propose a parallel discrete event simulation methodology of DCS using an object-oriented communication protocol model and Jefferson’s Time Warp mechanism. The protocol model transforms from discrete events sent by the finite state machine of device model to packets generated by the protocol layers, and also transforms into an opposite direction. The Time Warp mechanism assures that the device model can communicate all the packets in correct order by adding the send time and the receive time to the packets. By using the mechanism, the finite state machine and protocol model in the device model can progress the logical time, keeping the causality. We develop DCS simulation software for synchronizing the device models by applying the simulation methodology to the Java-based DCS simulation model implemented by using object-oriented design patterns. Finally, we confirm the usefulness of the software by the LonWorks-based DCS simulation for factory automation.