基于工厂物理学的缓冲柔性研究

Latest since the emergence of Factory Physics variability buffering is recognized as a key concept in operations management. Yet the formal link between buffer management and production control remains ill-understood. In this project, we define buffers as waiting process inputs (i.e. demand, flow items, and capacity), link buffer types to the three main functions of production control (i.e. due date setting, progress control, and capacity control), and develop the concept of buffer flexibility (which is defined as the capability of one input to adapt to other inputs). While eliminating or limiting the sources of variability is important, it is also important to recognize that buffer flexibility is another tool for management control. While buffer flexibility has been discussed in prior research, it has not been explicitly incorporated into production control theory. Some practitioner programs, such as the Theory of Constraints, have included the concept of buffer management. But these programs do not provide a comprehensive understanding of how to manage buffers. In order to achieve the Lean objective of minimizing buffer costs, there is a need to understand how to determine what types of buffers to use, how to exchange or swap buffers with each other and how to determine the required degree of buffer flexibility given a level of system variability. Using a design science approach this project aims at developing such a buffer management system. .This project examines how buffer flexibility affects the ability of the production control system to manage system variability with a minimum level of buffers. It builds on insights from Factory Physics by explicitly recognizing that a buffer management system is a component of the production planning and control system, in our case Workload Control. As such, it is responsible for determining the buffer size and location and for determining the flexibility of each buffer. The buffer management system must also constantly evaluate the results of its decisions to ensure that its decisions continue to be compatible with the environment. This requires real-time information and an adequate structure (sensor, server etc) to create and handle this information..Clarifying the relation in between buffers is the major objective of our first work package. Our second work package then examines how the buffer management system is influenced by Workload Control. Both work packages provide the theoretical grounding for our fourth work package which uses design science to develop a buffer management system. In order to adequately use design science, which relies on loops of actions and redesigns, moving back and forth between the theoretical and empirical worlds, our third work package develops a physical model factory. The focus on a model factory instead of a real factory environment is justified by easier adaptability and significant lower costs in terms of material, labor (no needs for students as test persons) and maintenance. The buffer management system will be implemented and tested in this model factory.

自工厂物理学出现以来，变动性缓冲一直被认为是运作管理中的一个关键概念。然而，缓冲管理与生产控制之间的正式联系仍不明确。本项目将缓冲定义为等待工序输入（即需求、工件流和产能），并建立缓冲类型与生产控制的三个主要功能（即交货期设置、进度控制和产能控制）的关联关系，提出缓冲柔性的概念。为了实现最小化缓冲成本的精益目标，采用设计科学研究的方法，建立一个模型工厂车间作为实验平台，通过理论运转和重设计的迭代，开发一套缓冲管理系统。缓冲管理不仅要确定缓冲的大小和位置，还应确定每种缓冲的柔性，因此必须持续对其决策结果进行评估，以确保其决策与执行环境的兼容性。这将需要实时信息的支撑，并通过适当的结构（传感器，服务器等）对其进行创建和处理。为开发缓冲管理系统，在给定系统变动性水平条件下，确定使用缓冲的类型、实现不同缓冲类型之间相互转换，以及确定缓冲柔性所需的程度，同时考察负荷控制对缓冲管理系统的影响。

本项目将缓冲定义为等待工序输入（即需求、工件流和产能），研究了缓冲类型与生产控制的三个主要功能（即交货期设置、进度控制和产能控制）的相互关系，提出缓冲柔性的概念。基于时间、库存和产能三种缓冲之间的关系，建立了缓冲和运营目标的管理方式，探究了缓冲的中介效应和调节作用；建立了模型工厂和仿真生产线，完成了缓冲管理的几项检验工作。研究内容和结果主要包括：（1）采用生产仿真方法证明了综合运用COBACABANA及POLCA两种控制系统的方案优于单独使用其中任何一种的方案，新的控制方案可以减少延迟百分比约50%，减少平均延迟30%以上；（2）基于仿真方法评估订单释放、订单分配，以及资源分配对具有多资源约束的按订单生产车间性能的综合影响；评估了车辆分配规则、订单释放规则以及调度规则的综合性能，还提出了面向高动态生产环境基于知识的AGV车间调度的多目标优化算法；（3）研究了多级装配系统的四种生产计划与控制方式（看板、物料需求计划、优化生产技术、需求驱动的物料需求计划）仿真评估与比较；（4）基于设计科学研究方法开发一种独立于所有生产管理概念的物料流问题诊断综合方法，该诊断方案经历五个公司的连续迭代优化，能够支撑恰当分析模型选择和物料流改善方案制定。项目的研究工作产出高质量SCI期刊论文21篇，SSCI期刊论文3篇，其中JOM和POM、IJPE各1篇，IJPR有13篇。项目负责人荣获2019年度广东省科技合作奖1项。