Iterative Optimization of Rule-Based Scheduling

Performance criteria of production scheduling system was divided into two categories: equipment-associated criteria (EAC) and job-associated criteria (JAC). The EAC are mainly related to the processing time of equipment while the JAC are related to the processing time, flow time and due date of jobs. Accordingly performance of the production scheduling system falls into two categories, that is, performance associated with equipment (PAE) and performance associated with jobs (PAJ). Both kinds of the performances are affected by the priority of equipment and jobs during scheduling. Based on the above observations we defined adjustable parameters that reflect the PAE and the PAJ respectively, and established the relationship between the parameters and the two kinds of performances. With the help of the parameters, a performance-feedback iterative optimization scheme for rule-based production scheduling was proposed and furthermore a scheduling prototype system was developed. The experimental results demonstrated that the proposed scheduling scheme can improve the total performance of manufacturing systems. Especially it can optimize the specific performances significantly according to the scheduling objective function.