Process planning and scheduling are two major plann in g and control activities that consume significant part of the lead-time, theref ore all attempts are being made to reduce lead-time by automating them. Compute r ...Process planning and scheduling are two major plann in g and control activities that consume significant part of the lead-time, theref ore all attempts are being made to reduce lead-time by automating them. Compute r Aided Process Planning (CAPP) is a step in this direction. Most of the existin g CAPP systems do not consider scheduling while generating a process plan. Sched uling is done separately after the process plan has been generated and therefore , it is possible that a process plan so generated is either not optimal or feasi ble from scheduling point of view. As process plans are generated without consid eration of job shop status, many problems arise within the manufacturing environ ment. Investigations have shown that 20%～30% of all process plans generated are not valid and have to be altered or suffer production delays when production sta rts. There is thus a major need for integration of scheduling with computer aide d process planning for generating more realistic process plans. In doing so, eff iciency of the manufacturing system as a whole is expected to improve. Decision support system performs many functions such as selection of machine too ls, cutting tools, sequencing of operations, determination of optimum cutting pa rameters and checking availability of machine tool before allocating any operati on to a machine tool. The process of transforming component data, process capabi lity and decision rules into computer readable format is still a major obstacle. This paper proposes architecture of a system, which integrates computer aided p rocess-planning system with scheduling using decision support system. A decisio n support system can be defined as " an interactive system that provides the use rs with easy access to decision models in order to support semi-structured or u nstructured decision making tasks".展开更多
针对多目标工艺规划与车间调度集成问题(multi-objective integrated process planning and scheduling,MOIPPS),以最小化完工时间和生产能耗最低为优化目标,提出了一种考虑全局和局部最优的改进混合优化算法。通过分析集成系统工艺设...针对多目标工艺规划与车间调度集成问题(multi-objective integrated process planning and scheduling,MOIPPS),以最小化完工时间和生产能耗最低为优化目标,提出了一种考虑全局和局部最优的改进混合优化算法。通过分析集成系统工艺设计和生产调度两个问题的区别与联系,搭建了多目标问题模型和解决框架。针对两阶段集成问题提出混合优化算法,对工艺阶段采用全局搜索算法,为集成系统提供多种工艺加工方案,保证集成算法的全局搜索性能;针对调度阶段设计一种改进禁忌搜索算法,通过交叉与随机抽样扩大解的分布范围,使用邻域禁忌搜索使得算法快速收敛,并采用Pareto非支配排序获得全局最优解。实验对比分析,验证了所提算法在求解多目标工艺规划与车间调度集成问题的高效性和稳定性。展开更多
针对多目标集成工艺规划与车间调度(Integrated Process Planning and Scheduling,IPPS)问题,建立了考虑完工时间、机器负载、总流程时间和机器利用率四个优化目标的IPPS问题模型。基于模拟退火算法和NSGAII算法提出了一种两阶段的混合...针对多目标集成工艺规划与车间调度(Integrated Process Planning and Scheduling,IPPS)问题,建立了考虑完工时间、机器负载、总流程时间和机器利用率四个优化目标的IPPS问题模型。基于模拟退火算法和NSGAII算法提出了一种两阶段的混合算法求解多目标IPPS问题。工艺规划阶段以最小化加工时间和机器负载为优化目标生成工件工艺路线,调度阶段以最小化完工时间、总流程时间和最大化机器利用率为优化目标生成调度方案,两个阶段交替迭代,完成问题求解。提出了一种工艺修正策略,对工艺阶段产生的工艺路线进行调整,来提高两个系统间的交互能力,从而提高算法的求解性能。最后设计了对比实验,用三种算法分别求解24组经典的IPPS问题案例。结果表明提出的混合算法和工艺修正策略在寻优能力和解的质量上都优于NSGAII算法,验证了提出的算法解决多目标IPPS问题的有效性。展开更多
为了实现以完工时间最短为目标的工艺规划与车间调度集成优化,提出了基于新编码遗传算法(Genetic Algorithm,GA)的集成优化方法。对工艺规划与车间调度集成优化(Integrated Process Planning and Scheduling optimization,IPPS)问题进...为了实现以完工时间最短为目标的工艺规划与车间调度集成优化,提出了基于新编码遗传算法(Genetic Algorithm,GA)的集成优化方法。对工艺规划与车间调度集成优化(Integrated Process Planning and Scheduling optimization,IPPS)问题进行了描述,并建立了完工时间最短的集成优化模型;设计一种具有最大柔性空间的染色体编码方法,从编码角度保证了集成优化问题的最大柔性度;根据IPPS问题特定约束改进了交叉变异方法,保证遗传操作前后均为可行解,使算法迭代均为有效迭代;进而制定了基于新编码遗传算法的IPPS问题求解流程。经Kim算例验证可知,与现有先进算法两阶段混合算法(Two-stage Hybrid Algorithm,THA)、改进蚁群算法(Enhanced Ant Colony Algorithm,EACA)和混合遗传算法(Hybrid Genetic Algorithm,HGA)相比,新编码GA在小规模、大规模生产情况下集成优化方案的完工时间均最小(分别为343、344、372、320、427及432 min),实验结果验证了新编码GA在IPPS问题求解中的可行性和先进性。展开更多
文摘Process planning and scheduling are two major plann in g and control activities that consume significant part of the lead-time, theref ore all attempts are being made to reduce lead-time by automating them. Compute r Aided Process Planning (CAPP) is a step in this direction. Most of the existin g CAPP systems do not consider scheduling while generating a process plan. Sched uling is done separately after the process plan has been generated and therefore , it is possible that a process plan so generated is either not optimal or feasi ble from scheduling point of view. As process plans are generated without consid eration of job shop status, many problems arise within the manufacturing environ ment. Investigations have shown that 20%～30% of all process plans generated are not valid and have to be altered or suffer production delays when production sta rts. There is thus a major need for integration of scheduling with computer aide d process planning for generating more realistic process plans. In doing so, eff iciency of the manufacturing system as a whole is expected to improve. Decision support system performs many functions such as selection of machine too ls, cutting tools, sequencing of operations, determination of optimum cutting pa rameters and checking availability of machine tool before allocating any operati on to a machine tool. The process of transforming component data, process capabi lity and decision rules into computer readable format is still a major obstacle. This paper proposes architecture of a system, which integrates computer aided p rocess-planning system with scheduling using decision support system. A decisio n support system can be defined as " an interactive system that provides the use rs with easy access to decision models in order to support semi-structured or u nstructured decision making tasks".
文摘针对多目标工艺规划与车间调度集成问题(multi-objective integrated process planning and scheduling,MOIPPS),以最小化完工时间和生产能耗最低为优化目标,提出了一种考虑全局和局部最优的改进混合优化算法。通过分析集成系统工艺设计和生产调度两个问题的区别与联系,搭建了多目标问题模型和解决框架。针对两阶段集成问题提出混合优化算法,对工艺阶段采用全局搜索算法,为集成系统提供多种工艺加工方案,保证集成算法的全局搜索性能;针对调度阶段设计一种改进禁忌搜索算法,通过交叉与随机抽样扩大解的分布范围,使用邻域禁忌搜索使得算法快速收敛,并采用Pareto非支配排序获得全局最优解。实验对比分析,验证了所提算法在求解多目标工艺规划与车间调度集成问题的高效性和稳定性。
文摘针对多目标集成工艺规划与车间调度(Integrated Process Planning and Scheduling,IPPS)问题,建立了考虑完工时间、机器负载、总流程时间和机器利用率四个优化目标的IPPS问题模型。基于模拟退火算法和NSGAII算法提出了一种两阶段的混合算法求解多目标IPPS问题。工艺规划阶段以最小化加工时间和机器负载为优化目标生成工件工艺路线,调度阶段以最小化完工时间、总流程时间和最大化机器利用率为优化目标生成调度方案,两个阶段交替迭代,完成问题求解。提出了一种工艺修正策略,对工艺阶段产生的工艺路线进行调整,来提高两个系统间的交互能力,从而提高算法的求解性能。最后设计了对比实验,用三种算法分别求解24组经典的IPPS问题案例。结果表明提出的混合算法和工艺修正策略在寻优能力和解的质量上都优于NSGAII算法,验证了提出的算法解决多目标IPPS问题的有效性。
文摘为了实现以完工时间最短为目标的工艺规划与车间调度集成优化,提出了基于新编码遗传算法(Genetic Algorithm,GA)的集成优化方法。对工艺规划与车间调度集成优化(Integrated Process Planning and Scheduling optimization,IPPS)问题进行了描述,并建立了完工时间最短的集成优化模型;设计一种具有最大柔性空间的染色体编码方法,从编码角度保证了集成优化问题的最大柔性度;根据IPPS问题特定约束改进了交叉变异方法,保证遗传操作前后均为可行解,使算法迭代均为有效迭代;进而制定了基于新编码遗传算法的IPPS问题求解流程。经Kim算例验证可知,与现有先进算法两阶段混合算法(Two-stage Hybrid Algorithm,THA)、改进蚁群算法(Enhanced Ant Colony Algorithm,EACA)和混合遗传算法(Hybrid Genetic Algorithm,HGA)相比,新编码GA在小规模、大规模生产情况下集成优化方案的完工时间均最小(分别为343、344、372、320、427及432 min),实验结果验证了新编码GA在IPPS问题求解中的可行性和先进性。
