A Study on a Real-Time Scheduling of Holonic Manufacturing System - Coordination Among Holons Based on Multi-Objective Optimization Problem -

Real-time scheduling for holonic manufacturing systems based on estimation of future status

“…Three types of real-time scheduling methods have been applied and compared. They are, the proposed method with the NN models for estimation of the future stats of HMS, one with the complete model for estimation which is described in section 2.6 (Iwamura et al 2004), and one without estimation which is described in section 2.3 (Iwamura et al 2003). The scheduling results of these methods are compared to verify the effectiveness of the proposed methods.…”

“…It is assumed that the individual holons have one of the objective functions shown in table 1 for evaluating the effectiveness values, in the previous research (Iwamura et al 2003). …”

“…It means that the training data are collected and stored during the execution of the real-time scheduling by applying the effectiveness-value-based method without estimation which is described in section 2.3. Therefore, the virtual HMS proposed in the previous report (Iwamura et al 2003) are modified, in order that the individual resource holons and job holons store the information of individual holons and the effectiveness values for the candidate holons to the database, when they evaluate the effectiveness values. The procedures to train the NN model are summarized in the following two steps.…”

“…In previous research (Iwamura et al 2003), real-time scheduling processes based on the effectiveness values have been proposed to select a suitable combination of the job holons and the resource holons, which carries out the machining process in the next time period.…”

“…The schedules obtained by the proposed NN models and ones by the effectiveness value based method without estimation (Iwamura et al 2003) are compared in order to evaluate the estimation accuracy of the NN models trained by the method described in the previous section.…”