基于ESPN的制造系统多任务可靠性研究

Analysis of Multitask Reliability for Manufacturing Systems Based on ESPN

以一个有三台机床并同时进行多个加工任务的制造单元为例,采用扩展随机Petri网对其进行多任务可靠性建模,该模型不仅可以适应任意分布的制造系统,同时克服了传统的可靠性建模方法无法兼顾制造系统生产过程的时间动态特性.在此基础上基于Petri网行为表达式,并将矩母函数思想引入其中,则不必生成可达标识图就可通过计算模型的传递函数,进而得到整个系统的多任务可靠度,由此可以更直观地反映具有多种加工任务的整个制造系统的运行性能.

Taking a manufacturing unit having three machines for simultaneous and multitask machining jobs as example, extended stochastic Petri nets （ESPN） is introduced to develop a muhitask reliability model adaptable to such manufacturing systems that process time are arbitrary distributions. In addition, the model rises above the difficulty that the time-dependent dynamic behavior in manufacturing process cannot be involved by way of conventional reliability modeling. For the reliability model of complex manufacturing systems, the concept of moment generating function is introduced in the behavior expression so as to obtain the muhitask reliability of the whole system by computing the transfer functions of the model without generating a reachability graph. In this way the performance in service of the whole manufacturing system for multitask machining jobs can be perceived clearer.