Application of simulation to the scheduling problem for a LED sorting system

The scheduling problem of LED chip sorting workstation is a multiprocessor open shop scheduling problem which is categorized as a NP-hard problem. In practice, this problem is usually solved with finding a dispatching rule to achieve certain performance indices through simulation. To find the most effective rule from five proposed dispatching rules was considered in this study. Experimental design was applied to find significant factors, and a two-stage process was used to select the best dispatching rule. In the first stage, where make-span as the performance index, three dispatching rules are selected for the next stage comparison, and they are common in applying LPT in bottleneck machines. In the second stage, a dispatching rule with applying SPT in non-bottleneck machines has least average queuing time among those three, and this rule is recommended for practical application.