An on-line controller for production systems with seasonal demands

Abstract

This paper investigated a hirarchical production planning and control model for flexible manufacturing systems that simultaneously make multiple parts subject to periodic demands. The off-line planning and on-line control strategy is utilized in the aggregate planning model. First, the optimal inventory levels are determined by the off-line planning model. The problem is formulated as a boundary-free discrete optimal control problem. When the actual inventory levels deviate from the optimal levels due to random interruptions, an on-line control problem is solved. The problem is formulated as a boundary-fixed discrete optimal control problem. The resulting large-scale problem is broken into a network flow problem and several single part aggregate production planning problems. The network flow problem determines the alternative routings among cells for given production rates. Single part production planning problems determine the production rates for each part in each period. Numerical examples illustrate the algorithm's efficiency.