基于扩展随机Petri网的可重组制造系统建模与分析方法

可重组制造系统(Reconfigurable manufacturing system,RMS)可根据市场变化进行组态调整和组元升级,系统的建模与分析方法必须能适应上述特点。提出基于扩展随机Petri网(Extended stochastic Petri nets,ESPN)的模块化建模方法,将RMS不同的加工资源对应于相应的ESPN基本模块,并通过过渡变迁合成ESPN模型,该模型能适应任意分布的制造系统,可更加精确地反映生产过程。在此基础上采用基于行为表达式的分析方法,得到系统性能指标,该分析方法可不必画出可达图而直接得到系统性能关系函数,使分析过程更加直观、简洁。可重组电动机生产线的实例证明了该建模与分析方法的有效性。

MODELING AND ANALYSIS OF RECONFIGURABLE MANUFACTURING SYSTEM BY EXTENDED STOCHASTIC PETRI NETS

Reconfigurable manufacturing system(RMS)em- phasizes quick reaction to market changes,whose components are reconfignrable structures.The modeling and analysis of such system are extremely difficult to develop.A modular modeling approach based extended stochastic Petri nets(ESPN)is pre- sented,which facilitates the reconfigurable processing model- ing and adapts the arbitrary distributions manufacturing system accurately.The RMS model is described by connecting a set of basic modules that are designed with respect to different re- sources and reconfignrable processing of operations;Their connection method is also provided.Furthermore,the analysis of ESPN model based on behavior expression is presented,and the performance measures of RMC are computed such as pro- duction rates versus the number of standby machines,part type mix ratio,and rump-up time.In addition,the relationship func- tion of performance can be easily obtained without the reach- ability graph of Petri nets.Thus,the analysis process is simple and straightforward.An example ofa DC motor reconfignrable production line is presented to illustrate the effectivity of the methodology.