SIMULATION-BASED DISTRIBUTED FUZZY CONTROL FOR WIP IN A MULTI-VARIETY AND SMALL-BATCH DISCRETE PRODUCTION SYSTEM WITH ONE TIGHTLY COUPLED CELL

This paper examines a multi-variety and small-batch production system with a tightly coupled cell. Using production data analysis, various random factors and constraints in a system with a tightly coupled bottleneck cell caused higher work-in-process (WIP) inventory levels and longer cycle times. Aiming to resolve these production problems, a two-dimensional distributed fuzzy controller with two correction factors has been developed. This heuristic approach is used to supervise the dynamic WIP inventory level changes and regulate the processing rate of each workstation with simple representations and linguistic IF-THEN rules. Based on consideration of certain major stochastic factors, a simulation model is explored with a control objective to maintain the WIP and cycle time at a low level. Simulation results show that this optimized control policy avoids system imbalances and eliminates bottlenecks. By comparison, the proposed approach significantly improves the system's performance and robustness.