The Planning Problem and a Solution Approach

For the planning of a multipurpose plant one has to map the structure of a master recipe to the detailed device structure of the plant with regard to a given time in the future. This process can be done automatically, e.g., with the SAP ERP system where it is called convert. The result is a process order as a concretization of a master recipe. A process order tells the production operator at which time and on which device a given batch production step has to be executed. This simple conversion can result in a situation where a selected device is already allocated to a different process order at the given time, thus the production plan may not be feasible. 

In case of allocation conflicts one has to choose a different time, a different structural variant (production version) or even both. The process of creating feasible production plans is denoted as scheduling. To support the solution of scheduling problems, a scheduling system is used. 

The scheduling task can be simplified by a reduction of the model (e.g., using single-step process orders that only consider the bottleneck resources). As usual, one has to compromise between effort and precision. 

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