The integration of production plan and operating schedule in a pharmaceutical pilot plant

In reality, planning and scheduling activities are loosely integrated. In the case of a complex supply chain, it might be too difficult to maintain both long-term and short-term information within one large model. However, in the case of a single facility and relative short time horizon this task becomes feasible. This is the case in a pharmaceutical pilot plant, where a 2- or 3-year planning horizon is the most one would expect due to frequent changes in the products and their demands. In earlier work, we decomposed the pilot plant planning and scheduling problem into long-term planning of resources and short-term scheduling of operations [Computer Aided Process Eng. 8 (2000) 1057]. The long-term plan is mainly concerned with allocation of human resource, such as operators, engineers, chemists, and analysts to projects that have uncertain timelines. The short-term schedule fixes the human resources and considers the scheduling of activities in the pilot plant itself. The algorithm resolves uncertainty in future projects by over-allocating resources so that, on average, resource constraints are met. In this paper, we continue this exploration. In particular, we explore techniques for combining the long- and short-term into one plan without creating undue burden on the solver and the planning group. The uncertainty is a daily life of a pharmaceutical pilot plant. We present a methodology to deal with it without compromising the accuracy of the operating schedule.