An opensource visual environment for discrete event simulation: DEOS. Part II: A test case in NATUZZI industries

DEOS (Discrete Event Object oriented Simulation) is a discrete event object oriented simulation environment developed by the University of Lecce. The real case of the automatic leather cutting system in Natuzzi industries has been analyzed as a proving ground for the software tool. A thorough study on alternative layout configurations has been conducted in order to obtain both performance indicators and economic indexes relative to the considered alternatives. First, the actual system layout and work cycle have been analyzed. The work-cycle encompasses: 1) a digit-phase in which leather characteristics are identified and their positions are recorded, 2) a scanning phase in which the leather placement is acquired by a vision system, 3) a nesting phase in which the optimal cutting program is computed, 4) a cutting phase and, finally, 5) an unload and packaging phase. The system is composed of two scanning tables each served by a human operator, a cutting table that serves alternatively both the two scanning tables and an unload station where a third human operator is employed in the unload operations. A simulation model of the elements that constitute the actual system has been developed using DEOS. The inferred objects have been visually linked to simulate the actual system and the model has been statistically validated by comparing the simulated results to the actual data. In the second step, several layout configurations have been simulated and benchmarked simply linking the modeled objects in different manners. To compare the different configurations both economic and performance parameters have been considered. The study has pointed out the effectiveness of the application of DEOS to identify three different but complementary strategies that can be adopted to improve the system performance.