Schedule coordination of parallel machines in large manufacturing systems

在高度混合、小量生產模式下，如何配置工件給平行機器是一個重要的作業管理決策，在沒有事先規劃的製造環境，實務上互動式配置是很普遍的，但很少在研究上受到注意， 在序列批次作業中，工件隨機到來並以工件形式組成批次，置放於等候線。 平行機器的工單指派是一個常見的製造決策與電腦科學問題，在很多情況，工單的到達情況與機器的妥善狀況是隨時變化的，工單的反應式排程的主要目標是在發生不預期的情況，對既有的排程進行快速修補，這需要對工單組合的快速分析方法與知識法則。本文以普瓦松過程表示工單到達的不確定性，以分析法推導不同工單組合對設定轉換機率的效果，導出不均勻工單組合要優於均勻工單組合的知識法則，首先分析批次方式生產時工件組合的影響，機台設定的機率由工件先到先上機、以時間長短為批次、及以工件數量為批次三種狀況下進行分析，顯示出不均勻組合比均勻組合時有較好的設定轉換結果，在三個批次方法下以最小化機台所有設定轉換次數為績效準則，將部分派工法則建置起來，且以單一機台證明之，並將知識法則應用到突然有緊急工件發生時，說明在此配置規則的動態應變功能。 本論文研究對工單指派的工作負載，推導出不必動用優化軟體的快速估算方法。這兩項結果都是基於數理分析，提供快速解法，適合應用在反應式的工單指派問題。同時探討大型工廠製造多樣複雜的產品型態，通常會由數個工作站來執行生產，而且在工廠層級與工作站層級各有其控管功能。然而各別工作站傾向於注重有效發揮機台使用率，工廠管理最高層級通常著重產品流程管制。在二個組織層級運作決策之整合可以補償由於不同目標造成之產能損失。本文呈現在隨機多樣複雜的產品型態，必需作機台設定轉換之序列批次上機台生產狀況下，工件批次決策之調整方法，首先分析在流程時間之批次方法效能，導出以時間批次決策前提下設定轉換機率close-form方程式，接著探討在二個組織層級之差異，並設計一個以state-based 作為績效評量之整合模式，輔以數值模擬與迴歸方法用來驗證此一模式，發展出分散垂直整合調整方法，其涵蓋水平整合排程與垂直分散整合製造在架構設計之功能分析。Assigning jobs to parallel machines is a classic problem in manufacturing and computer science. In many manufacturing environments, machines availability and job orders might change dynamically. The aim of reactive scheduling is mainly to revise a previous schedule. Reactive scheduling requires fast methods and knowledge rules in response to unexpected events. This research presents some analytical rules on the dominance relationships on job mixings under Poisson job arrival and a method for estimating machine workload when there are alternative machines. It is found that uneven mixings of job types are better than even mixings in reducing setup time. An iterative procedure is shown to converge in workload balancing and the resultant makespan. Workload can be estimated with accuracy without running time-consuming optimization programs. Applications are demonstrated with numerical examples. Large factories that manufacture high mixes of complex products are usually composed of a number of workstations and the manufacturing control function is divided between a factory and a workstation level. While the management of individual workstations tends to focus on efficient machine utilization, the top-level factory management is usually concerned with job flow control. Integration of operation decisions between the two organization levels can recover productivity loss stemming from disparate objectives. This research also presents a method for aligning the job batching decision for serial-batch machines that require machine setup to serve stochastic arrivals of multiple job types. The effect of batching on flow time is first analyzed and closed-form formulas for the probability of setup are derived for a time-based batching policy. The misalignment in batching decisions at the two organization levels is next illustrated. Finally, a state-based performance measure is designed for decision integration. Numerical simulation and regression are used to test the proposed method. The main contribution of this paper is on developing a distributed vertical alignment method which compliments the approaches of horizontal coordinated scheduling and vertical functional decomposition in architecture design of distributed manufacturing control