A Multi-Pass Simulation-Based, Real-Time Scheduling and Shop Floor Control System

摘要

Significant shop scheduling and control research has been conducted in the past several decades. More-over, real-time shop floor scheduling and control research also has been conducted in the past ten years. However, there have been no reports of automated, real-time, on-line, multi-pass simulation-based shop floor control and scheduling being used in practice. This paper documents the implementation of a multi-pass simulation-based, real-time scheduling and shop floor control system in the Computer Integrated Manufacturing (CIM) Lab at Pennsylvania State University. This research is based on technologies developed in the RapidCIM project at Pennsylvania State and Texas A&M Universities, as well as developments described herein. A multi-pass simulation is composed of two simulations-a real-time simulation and a preview simulation, which runs in the fast mode. The real-time simulation acts as a real-time shop floor controller, whereas the fast-mode simulation acts as a real-time scheduler. At each decision point in real-time simulation, a deter-ministic fast-mode simulation is evoked to see what control policy impacts the current system most favorably. This control policy is then fed to the real-time simulation for execution on the system. The multi-pass simulation system is implemented using Arena 3.01. The implementation scheme issues were investigated in great detail. A Visual Basic Application (VBA) embedded in Arena 3.01 plays an important role in making this implementation possible. Experiments to evaluate the performance of the proposed multi-pass simulation have yielded throughput increases of 138% over single-pass, single-rule dispatching procedures. For different system instances, there may be even greater improvements in throughput performance.