生产制作系统项目执行.ppt

仿真模型结构 除以上事件，第二种情况下仿真模型还包含以下事件: 机床故障 机床维修完成 工件传输装置故障 工件传输装置维修完成 刀具传输装置故障 刀具传输装置维修完成 工件加工模块 工件加工策略包含在FMS的输入端选择工件装载到托盘上。为了做出这一决策,需要赋给待加工工件一个优先级值。 选择拥有最高优先级的工件进入系统进行加工。 本文采用了如下7种调度规则。 7种调度规则 FCFS:first come first served SPT:shortest processing time EDD:earliest due date EMDD:earliest modified due date FNOP:fewest number of operations MNOP:most number of operations SLACK 刀具需求选择模块 在某一时刻,有多个刀具请求,需要应用调度规则赋给每个工件一优先级值,根据优先级值选择优先满足哪个工件的刀具需求。 本文采用了12条刀具调度规则。 12种调度规则 1.FCFS 2.SPT 3.EDD 4.EMDD 5.CR:critical ratio 6.AT-RPT 7.PT/TIS 8.Slack 9.PT+slack 10.CR+SPT 11.S/RPT+SPT 12.EDD+SPT 输出模块 模型运行 零件加工7种调度规则 刀具需求选择12种调度规则 组合成7*12=84实验情形 每一种情形重复实验10次 系统稳定后收集统计实验数据 1250=250+1000 Results and discussion Scenario1 Ranking for the part launching decision Mean flow time: SPT,EMDD Mean tardiness: SPT,EMDD Mean waiting time for tool: EMDD, SLACK, EDD, SPT, FCFS Percentage of tardy parts: SPT, EMDD Ranking for the tool request selection FCFS provides the best performance Scenario2 Mean flow time SPT 805.27 802.53 Results and discussion Scenario 2 Mean flow time SPT-(EDD+SPT) SPT-(EMDD) Mean tardiness 220.34 224.58 221.73 Results and discussion Scenario 2 Mean tardiness SPT-EMDD EMDD-(EDD+SPT) SPT-(EDD+SPT) Mean waiting time for tool 341.30 Results and discussion Scenario 2 Mean waiting time for tool EDD+SPT Percentage of tardy parts 31.12 Results and discussion Scenario 2 Percentage of tardy parts SPT-(EDD+SPT) ANOVA results Part launching rule is significant for all performance measures, tool request selection is not significant for any of the performance measures. Multiple comparison test for part launching 821.30 862.94 231.96 235.62 33.29 41.95 346.44 351.16 350.02 351.08 Results and discussion Scenario 2 ANOVA results Mean flow time： SPT，EMDD Mean tardiness： SPT，EMDD Mean waiting time for tool：EDD，EMDD，MNOP，SLACK Percentage of tardy parts： SPT，EMDD Desirable operational policies Comparison of results for the two scenarios Results and discussion Desirable operational poli