Evaluation of Production Schedules Considering Uncertainty of Processing Time Based on Probability Density Function

Abstract

In make-to-order production systems, machining tools and processes are not assigned when the orders are received. Therefore, it is difficult to make an accurate production schedule. This study proposes a method to estimate the probability distribution of the make-span from the probability density function of the processing time in the job shop scheduling problem that includes tasks whose processing time is uncertain. Furthermore, based on the expected value and standard deviation of the make-span of the created production schedule, we propose a method for deriving a production schedule that is oriented toward minimizing the value of the make-span and its uncertainty. We also carry out computational experiments to evaluate the effectiveness of the proposed method.