On the simulation run length: A step towards real time control in an FMS

In any real time control system, its scheduling and control policy should be reassessed every time the state of the system changes. In large and complex systems, this could be a self-defeating goal. Implementing real time control in such systems would require an enormous amount of computation time. Determination of discrete time interval (simulation window length) is the main objective of this study. To implement and demonstrate this methodology, the authors selected a Flexible Manufacturing System which approximates a dynamic job shop. The Expert Control System developed in this study integrated programmes for different functions and employed multi-pass simulation to determine the best scheduling strategy in the system. The simulation output is then subjected to Analysis of Variance and Newman-Keuls’ range tests to obtain a ‘good’ simulation window length for different performance criteria of optimisation.