Decision-making method of reconfigurable manufacturing systems’ reconfiguration by a Gale-Shapley model

The companies need to rapid response to new product introduction, mix and demand changes to stay competitive. A reconfigurable manufacturing system can quickly react to changes in products and market. The control method to reconfigure the machines of a reconfigurable manufacturing system is crucial for the performance level. This paper proposes a reconfiguration decision-making method based on a Game-Theory algorithm, and in particular the Gale-Shapley model. A periodic review strategy is used to create two sets: one set of machine over-loaded and one set under-loaded. The Gale-Shapley model forms a coupled of over-loaded and under-loaded machines. The reconfiguration concerns the under-loaded machine of the coupled adding also the task performed by the over-loaded machine. This paper presents a simulation environment developed to evaluate the proposed method and highlight the main topics. The simulation results highlight how the game-theory approach developed improves all the performance measures with controlled number of machines’ reconfigurations.     

Digital twin-driven rapid reconfiguration of the automated manufacturing system via an open architecture model

Increasing individualization demands in products call for high flexibility in the manufacturing systems to adapt changes. This paper proposes a novel digital twin-driven approach for rapid reconfiguration of automated manufacturing systems. The digital twin comprises two parts, the semi-physical simulation that maps data of the system and provides input data to the second part, which is optimization. The results of the optimization part are fed back to the semi-physical simulation for verification. Open-architecture machine tool (OAMT) is defined and developed as a new class of machine tools comprising a fixed standard platform and various individualized modules that can be added and rapidly swapped. Engineers can flexibly reconfigure the manufacturing system for catering to process planning by integrating personalized modules into its OAMTs. Key enabling techniques, including how to twin cyber and physical system and how to quickly bi-level program the production capacity and functionality of manufacturing systems to adapt rapid changes of products, are detailed. A physical implementation is conducted to verify the effectiveness of the proposed approach to achieving improved system performance while minimizing the overheads of the reconfiguration process by automating and rapidly optimizing it.     

Reconfiguration point decision method based on dynamic complexity for reconfigurable manufacturing system (RMS)

To address the problem of how to identify the best time to implement reconfiguration for the reconfigurable manufacturing system (RMS), a dynamic complexity-based RMS reconfiguration point decision method is proposed. This method first identifies factors that affect RMS dynamic complexity (including both positive and negative complexity) at the machine tool and manufacturing cell levels. Next, based on information entropy theory, a quantitative model for RMS dynamic complexity is created, which is solved via state probability analysis for processing capability and the processing function. This model is combined with cusp catastrophe theory to establish an RMS reconfiguration decision model. Both positive and negative complexity are control variables for cusp catastrophe. Cusp catastrophe’s state condition is used to identify RMS state catastrophe at the final stage of production. This catastrophe point is the RMS reconfiguration point. Finally, the case study result shows that this method can effectively identify the RMS state catastrophe moment so that system reconfiguration is implemented promptly to improve RMS’s responsiveness to the market.     

Assessment of reconfiguration schemes for Reconfigurable Manufacturing Systems based on resources and lead time

Reconfigurable manufacturing equipment is developed to meet the growing demand for more agile production. Agile manufacturing technology can improve the turnover of a company if it enables fast market introduction for volume production. Modular reconfiguration, defined as changing the structure of the machine, enables larger variation of products on a single manufacturing system; these solutions are called Reconfigurable Manufacturing Systems (RMS). The quality of RMS, and the required resources to bring it to reliable production, is largely determined by a swift execution of the reconfiguration process. This paper proposes a method to compare alternatives for the ways to implement reconfiguration. Three classes of reconfiguration are defined to distinguish the impact of the proposed alternatives. The procedure uses a recently introduced index method for development of RMS process modules, based on the Axiomatic Design methodology. Weighting factors are used to calculate the resources and lead time needed to implement the reconfiguration process. Application of the method leads to quick comparison of alternatives in the early stage of development. Successful execution of the method was demonstrated for the manufacturing process of a 3D measuring probe.     

Automatic Reconfiguration of Petri Net Controllers for Reconfigurable Manufacturing Systems With an Improved Net Rewriting System-Based Approach

The advent of reconfigurable manufacturing systems (RMSs) has given rise to a challenging problem, i.e., how to reconfigure rapidly and validly a RMS supervisory controller in response to frequent changes in the manufacturing system configuration driven by fluctuating market. This paper presents an improved net rewriting system (INRS)-based method for automatic reconfiguration of Petri net (PN) supervisory controllers for RMS. We begin with presenting the INRS which overcomes the limitations of the net rewriting system and can dynamically change the structure of a PN without damaging its important behavioral properties. Based on INRS, a method for design reconfigurable PN controllers of RMS is introduced. Subsequently, we presented an INRS-based method for rapidly automatic reconfiguration of this class of PN controllers. In the reconfiguration method, changes in a RMS configuration can be formalized and act on an existing controller to make it reconfigure rapidly into a new one. Noticeably, no matter the design or reconfiguration, the expected behavioral properties of the resultant PN controllers are guaranteed. Thus, efforts for verification of the results can be avoided naturally. We also illustrate the reconfiguration of a PN controller for a reconfigurable manufacturing cell.     

Rapid design and reconfiguration of Petri net models for reconfigurable manufacturing cells with improved net rewriting systems and activity diagrams

To respond rapidly to the highly volatile market, the emerging reconfigurable manufacturing systems (RMS) have brought forward two challenging issues, namely, how to build rapid a formal model of an initial manufacturing configuration and how to yield the goal model from the existing one along with manufacturing configuration changes (reconfiguration). As for the issues, we present in this paper a method for rapid design of Petri net (PN) formalized models of RMS, intended for supervisory control and logic control of RMS, as well as a method for automated reconfiguration of the models. Firstly, we present an improved net rewriting system (INRS) for dynamically operating net transformation, unlike its predecessor-net rewriting system, where the initial behavioral properties of the underlying PN rewritten can be preserved during the transformation. Subsequently, the paper proposes the three-phase method for rapid design of initial full PN models of reconfigurable manufacturing cells (RMCs). In this method, activity diagrams of Unified Modeling Languages version 2 (UML 2) are used to describe manufacturing configurations, firstly; then the sub-activity diagrams are transformed into PN sub-models; finally, the PN sub-models are automated synthesized into a full model by the approach of INRS. Further, we present a model reconfiguration method for this class of PN models. The method compares changes in activity diagrams of the existing and goal manufacturing configurations and converts them into net rewriting rules of INRS. By applying the rules obtained, the existing PN model can reconfigure into a new one for the goal manufacturing configuration. No matter the design method or the reconfiguration method, the behavioral properties of the obtained PN models, e.g., liveness, boundedness, or reversibility, can be guaranteed and thereby the efforts of verification can be avoided. Finally, rapid design of a PN model of a reconfigurable manufacturing cell, as well as its automated reconfiguration, is illustrated with the help of an example. The result indicates the validity of the methods.     

A non-dominated sorting genetic algorithm based approach for optimal machines selection in reconfigurable manufacturing environment

This paper deals with a problem of reconfigurable manufacturing systems (RMSs) design based on products specifications and reconfigurable machines capabilities. A reconfigurable manufacturing environment includes machines, tools, system layout, etc. Moreover, the machine can be reconfigured to meet the changing needs in terms of capacity and functionality, which means that the same machine can be modified in order to perform different tasks depending on the offered axes of motion in each configuration and the availability of tools. This problem is related to the selection of candidate reconfigurable machines among an available set, which will be then used to carry out a certain product based on the product characteristics. The selection of the machines considers two main objectives respectively the minimization of the total cost (production cost, reconfiguration cost, tool changing cost and tool using cost) and the total completion time. An adapted version of the non- dominated sorting genetic algorithm (NSGA-II) is proposed to solve the problem. To demonstrate the effectiveness of the proposed approach on RMS design problem, a numerical example is presented and the obtained results are discussed with suggested future research.     

可重配置DNC系统的设计与实现

为了使DNC系统适应不同配置的制造单元,同时有效地控制和管理制造单元中数控机床的加工过程,该文从DNC系统的控制软件可重配置以及硬件通讯平台可重配置的角度出发,提出了一种可重配置制造单元中数控机床的DNC控制设计方法,同时采用面向对象技术进行DNC系统软件的设计和开发,所开发的系统集NC程序编辑、NC程序管理、DNC控制为一体,能够满足动态单元和可重构制造单元等DNC的控制要求。     

一种围棋定式的机器学习方法

提出了一种围棋定式的机器学习方法。利用此方法可实现从棋谱库中自动提取定式并生成定式库。此外，对于棋谱数量较大的情况，采用分阶段学习方法，提高了学习效率。应用此方法，时34000局棋谱进行处理，得到定式点680638个。最后，还给出了1种基于组合博弈理论在计算机围棋博弈系统中使用定式的方法。     

Design,refinement, implementation and prototype testing of a reconfigurable lathe-mill

This article documents the design, refinement, and implementation of a reconfigurable machine tool that provides a flexible platform for turning and milling. Advances in the design and capabilities of machine tools drive modern industry. In fact, the expanding capabilities of the machines permit novel and economic changes in the manufacturing and design of products. After the flexible manufacturing (FMS) boom, a more recent, but no less significant, area of machine development involves the reconfiguration of milling machines. This reconfigurability can also be applied to lathe-mills. The present work demonstrates satisfactorily the reconfiguration characteristics of modularity, integrability, and convertibility. We prototype and test a completely functional bench top reconfigurable lathe mill machine implemented using a $10,000 USD budget and developed following a synthesized machine tool product development methodology that begins with concept design and cutting forces to end in prototyping. In addition to reasonable results in runout, positioning, and surface roughness, the machine demonstrates the capability to produce parts with a Cpk of 1.009, thereby demonstrating the ability to fabricate this type of machine in Mexico for the local jewelry industry.     

可重构制造系统监督控制器的自动重构

提出了基于改进的网重写系统(Improved net rewriting system, INRS)的可重构制造系统(Reconfigurable manufacturing systems, RMS) Petri网监督控制器的自动重构方法, 以快速适应由市场需求变化所引起的制造系统构形的频繁变化. INRS解决了网重写系统存在的问题, 可动态调整给定Petri网模型的结构而不改变其行为属性. 以集合和图的组合形式定义了RMS的构形, 并提出了基于INRS的一类模块化、可重构的Petri网控制器的设计方法. 针对这类Petri网控制器, 提出了基于INRS的自动重构方法. 方法可将RMS构形的变化转变为INRS的图重写规则, 并作用于当前Petri网控制器, 使其快速、自动地重构为所求的新控制器. 所提出的Petri网控制器的设计与重构方法, 均从理论上保证了结果的正确性, 免校验. 仿真研究验证了方法的有效性.     

面向网络化制造的产品再配置模型

该文提出一个面向网络化制造的产品再配置概念模型．该模型突出配置过程的动态特性,在分析了基于版本模型的部件、配置模型演化方式以及两者在演化过程中的相互影响的基础上,给出在集成产品配置的产品数据管理系统中对部件演化和模型演化进行跟踪和记录的方法,以实现产品再配置．该模型具有较强的时态描述能力,可广泛应用在网络化制造系统中．最后还提出了一个面向网络化制造的产品再配置结果相关度匹配算法．     

A flexible data schema and system architecture for the virtualization of manufacturing machines (VMM)

Future factories will feature strong integration of physical machines and cyber-enabled software, working seamlessly to improve manufacturing production efficiency. In these digitally enabled and network connected factories, each physical machine on the shop floor can have its ‘virtual twin’ available in cyberspace. This ‘virtual twin’ is populated with data streaming in from the physical machines to represent a near real-time as-is state of the machine in cyberspace. This results in the virtualization of a machine resource to external factory manufacturing systems. This paper describes how streaming data can be stored in a scalable and flexible document schema based database such as MongoDB, a data store that makes up the virtual twin system. We present an architecture, which allows third-party integration of software apps to interface with the virtual manufacturing machines. We evaluate our database schema against query statements and provide examples of how third-party apps can interface with manufacturing machines using the VMM middleware. Finally, we discuss an operating system architecture for VMMs across the manufacturing cyberspace, which necessitates command and control of various virtualized manufacturing machines, opening new possibilities in cyber-physical systems in manufacturing.     

Simulation of a production line system with machine breakdowns using network modeling

In a manufacturing system, several factors can affect the reliability of the system in producing expected output levels, including resource input rates, labor rate variability, product quality, and machine failures. Although all of these factors will be reflected in the modeling process presented in this paper, the primary focus will be on the effect of machine breakdowns on system output. Network modeling and simulation with Q-GERT is the vehicle of analysis that is employed. This technique will be demonstrated via a realistic case example encompassing a complex production system consisting of several assembly lines, each containing several machines. The statistical results of the simulation of the example system are presented and discussed. In addition, examples of how the simulation model can be used to test changes in machine repair times and breakdown rates will be presented.     

Fault tolerant emergency control to preserve power system stability

This paper introduces a method for fault-masking and system reconfiguration in power transmission systems. The paper demonstrates how faults are handled by reconfiguring remaining controls through utilisation of wide-area measurement in real time. It is shown how reconfiguration can be obtained using a virtual actuator concept, which covers Lure-type systems. The paper shows the steps needed to calculate a virtual actuator, which relies on the solution of a linear matrix inequality. The solution is shown to work with existing controls by adding a compensation signal. Simulation results of a benchmark system show ability of the reconfiguration to maintain stability.     

Production scheduling with subcontracting: the subcontractor’s pricing game

This paper studies a two-stage game with a manufacturer and a subcontractor who are faced by a production scheduling problem. The manufacturer has a set of jobs to process, a subset of which can be subcontracted to the subcontractor to reduce the tardiness cost. In the game, the subcontractor makes the first decision to ask for a unit price of his machine time to be used by the manufacturer, and then the manufacturer follows to decide which jobs to be subcontracted to process and how the production scheduling is made. We analyze the game and derive how the subcontractor can optimize the unit price to maximize his profit. We then investigate the performance of such a simple contract from the viewpoint of coordination, and propose two other contracts that can achieve coordination between the two players.     

Synchronization-oriented reconfiguration of FPAI under graduation intelligent manufacturing system in the COVID-19 pandemic and beyond

Companies with manufacturing systems that are more responsive and resilient will be able to survive or even gain market shares in the face of the unpredicted variable of an outbreak similar to the COVID-19 pandemic. Motivated by an industrial company restructuring its manufacturing system with the layout of fixed-position assembly islands (FPAI) during the COVID-19 pandemic, this paper introduces the synchronization-oriented reconfiguration of FPAI under Graduation Intelligent Manufacturing System (GiMS). Inspired by the graduation ceremony, a novel manufacturing mode-Graduation Manufacturing System (GMS) with ticket-based reconfigurable structures, is designed for organizing production operations with simplicity and resilience for the layout of FPAI. The IIoT and digital twin-enabled GiMS is developed for transforming real-time visibility in operations to support the reconfiguration of the manufacturing system. A synchronization-oriented reconfiguration mechanism is proposed to achieve the synchronous interaction among changing customer demand, island configuration, and production activities allocation rapidly and cost-effectively. Cloud services integrating the proposed reconfiguration mechanism are developed for managers and onsite operators for supporting the successful reconfiguration implementation with enhanced operational visibility. Through the case study of an industrial company, the effectiveness of the proposed concept and approach is verified.     

企业组织与过程的优化重构

可重构性是企业管理系统复杂性和响应环境变化 ,以及同其它企业竞争与合作的核心能力 .由于企业是一个复杂的社会 -技术系统 ,组织与过程的优化重构是制造资源优化配置的基础 .本文首先讨论了企业组织重构的影响因素和企业之间组织重构基本形式 .然后 ,本文讨论企业过程优化重构中渐变 /突变方式、建模问题和关联性分析方法 .企业组织与过程的优化重构技术将有效促进供应链管理、动态联盟和网络化制造等的发展     

Assessing ease of reconfiguration of conventional and Holonic manufacturing systems: Approach and case study

This paper focuses on comparing the ease of reconfiguration of Holonic and conventional manufacturing systems (HMS and CMS). By using the recently proposed guideline for assessing ease of reconfiguration [Covanich, W., McFarlane, D., Farid, A.M., 2008. Guidelines for Evaluating the Ease of Reconfiguration of Manufacturing Systems. Daejeon, South Korea. INDIN08], the paper evaluates the effort required to introduce a new machine into both conventional and Holonic manufacturing systems. Examining particularly the ease of reconfiguration, it is found that HMS with conventional hardware may have little advantage over CMS, while HMS with ideal hardware appears to have significant advantage over CMS.     

Ontology-based reconfiguration agent for intelligent mechatronic systems in flexible manufacturing

This paper proposes a novel approach to achieving fast reconfiguration of modular manufacturing systems, based on an ontology-based reconfiguration agent. The agent uses ontological knowledge of the manufacturing environment for the purpose of reconfiguration without human intervention. The current mass customization era requires increased flexibility and agility in the manufacturing systems to adapt changes in manufacturing requirements and environments. Our configuration agent minimises the overheads of the current reconfiguration process by automating it. It infers facts about the manufacturing environment from the ontological knowledge model and then decides whether the current environment can support the given manufacturing requirements. This paper proposes the agent architecture enabling the integration between the high level planning with the distributed low level control compliant with the upcoming IEC 61499 function blocks standard.