Ting Qu

Agent-based workflow management for RFID-enabled real-time reconfigurable manufacturing

Recent developments in wireless technologies have created opportunities for developing reconfigurable wireless manufacturing systems with real-time traceability, visibility and interoperability in shop-floor planning, execution and control. This paper proposes to use agent-based workflow management as a mechanism to facilitate interactions among RFID-enabled reconfigurable manufacturing resources. A production process is modelled as a workflow network. Its nodes correspond to the work (process), and its edges to flows of control and data. Nodes are represented as agents and edges as messages. As a sandwich layer, agents wrap manufacturing services around a work-cell and their operational logics/intelligence for cost-effectively collecting and processing real-time manufacturing data, forming so-called work-cell gateways. A reference framework for a shop-floor gateway is proposed based on the three key components: Workflow management, manufacturing services universal description, discovery and integration (namely MS-UDDI) and work-cell agents. Work-cell agents are packaged, registered and published at MS-UDDI as web services which are easily reused and reconfigured in the workflow for a specific production process. Finally, a prototype system is presented to demonstrate how the proposed method is used to define and execute a real-time reconfigurable manufacturing project.

Radio frequency identification-enabled real-time manufacturing execution system: A case study in an automotive part manufacturer

Automotive vehicle manufacturers have been at the forefront of employing radio frequency identification (RFID) technology for their manufacturing logistics management. They have benefited from RFID-enabled shop-floor visibility and traceability, which have in turn facilitated the implementation of advanced manufacturing strategies such as just-in-time lean manufacturing and mass customisation. Initial successes have attracted attention and interests from small- and medium-sized enterprises (SMEs) involved in automotive part and component manufacturers down the automotive vertical. However, high levels of capital investments and technical skills have created practical hurdles for automotive SMEs to gain RFID benefits. This article reports on an industrial case study about the RFID implementation project at a typical SME engine valve manufacturer. This company manufactures a large variety of engine valves with a mixture of large and small orders. Work-in-progress items across the company have accumulated to an extreme level for human operations and decisions. The company adopted RFID-enabled shop-floor manufacturing solutions across the whole operations with little experience in the use of information systems/technology. Based on RFID-enabled real-time shop-floor data, the company has extended the efforts in setting up and integrating manufacturing execution system and enterprise resource planning system. The success of this case company demonstrates that RFID is not just for automotive giants but also practically useful to SME suppliers. The article presents a framework that has been followed by this case company with a hope that experiences and insights are useful to other automotive SMEs.

A case of implementing RFID-based real-time shop-floor material management for household electrical appliance manufacturers

Radio Frequency Identification (RFID) technologies provide automatic and accurate object data capturing capability and enable real-time object visibility and traceability. Potential benefits have been widely reported for improving manufacturing shop-floor management. However, reports on how such potentials come true in real-life shop-floor daily operations are very limited. As a result, skeptics overwhelm enthusiasm. This paper contributes to the re-vitalization of RFID efforts in manufacturing industries by presenting a real-life case study of applying RFID for managing material distribution in a complex assembly shop-floor at a large air conditioner manufacturer. The case study discusses how technical, social and organizational issues have been addressed throughout the project within the company. It is hoped that insights and lessons gained be generalized for future efforts across household electrical appliance manufacturers that share similar shop-floor.

Agent-based Smart Gateway for RFID-enabled real-time wireless manufacturing

Radio frequency identification (RFID) technology enables real-time traceability, visibility and interoperability of manufacturing resources and thus improves the performance of shop-floor planning, execution and control. However, a big challenge faced by manufacturers now is to deal with various RFID/Auto-ID technologies which are necessary in different production situations yet entailing different development technologies. This paper presents an innovative all-in-one Smart Gateway technology for capturing real-time production data from various manufacturing resources attached to different types of RFID/Auto-ID devices. Each of such manufacturing resources forms a smart object (SO) while agent concept is introduced for encapsulating the heterogeneous SOs. Taking advantages of web services, agents are developed and managed in a standard way following service-oriented architecture (SOA). Smart objects and agents are dynamically deployed and reconfigured at a Smart Gateway in a ‘plug and play’ fashion. The joint work among smart objects is governed by an agent-based workflow management (AWFM) mechanism. The proposed framework and core technologies are demonstrated by an assembly workstation case where a Smart Gateway is deployed for defining, configuring and executing assembly operations on a real-time basis.

RFID-enabled real-time advanced planning and scheduling shell for production decision making

In a radio frequency identification (RFID)-enabled real-time manufacturing environment, different decision makers are often confronted with the inconsistency between the highly synchronised information flow and unstandardised decision-making procedures, especially under conflicting objectives and dynamic situations. This study proposes an RFID-enabled real-time advanced production planning and scheduling shell (RAPShell, in short) to coordinate different decision makers across production processes. RAPShell has several key innovations. First, it uses RFID technology for enhancing information sharing, which provides the basis for coordinating decisions and operations of different parties involved in production planning, scheduling, execution and control. Second, it adopts Software as a Service (SaaS) model and a standard service-oriented architecture (SOA) with key modules, adaptive optimisation models, solution algorithms as well as scheduling rules developed and deployed as web services. Finally, extensible makeup language (XML)-based data models are utilised to achieve easy-to-deploy and simple-to-use system customisation and implementation. A case study demonstrates how RAPShell is customised and deployed in a small- and medium-sized company to facilitate the operations of typical production decision makers and operators. Benefits from qualitative and quantitative are discussed from the case study to show RAPShells practical effectiveness and efficiency on production decision making.

RFID-enabled real-time manufacturing information tracking infrastructure for extended enterprises

In extended enterprises, real-time manufacturing information tracking plays an important role and aims to provide the right information to the right person at the right time in the right format to achieve optimal production management among the involved enterprises. However, many enterprises are caused by lack of timely, accurate and consistent manufacturing data. The laggard information transfer flow and the unmatched information transfer method bring extended enterprises much more uncertainty and unknowingness. This paper proposes a RFID-enabled real-time manufacturing information tracking infrastructure (RTMITI) to address the real-time manufacturing data capturing and manufacturing information processing methods for extended enterprises. Following the proposed infrastructure, the traditional manufacturing resources such as employees, machines and materials are equipped with RFID devices (Readers and Tags) to build the real-time data capturing environment. In addition, a series of manufacturing information processing methods are established to calculate and track the real-time manufacturing information such as real-time manufacturing cost, progress, WIP (Work-in-progress) inventory etc. in parts/assemblies/products at machines/shop floors/enterprises/ extended enterprises levels. Finally, a case study is given to demonstrate the developed framework and corresponding methodologies.

Deadlock recovery for flexible manufacturing systems modeled with Petri nets

This paper deals with deadlock problems in Petri nets by adding a set of recovery transitions. Different from traditional deadlock control methods by deploying control places for a net model to be controlled, this work adds transitions to a net model to recover all deadlock markings. First, we present an iterative approach. At each iteration step, an integer linear programming problem (ILPP) is formulated to design a recovery transition and the objective function is used to maximize the number of deadlock markings recovered by the obtained transition. The process is carried out until all deadlock markings are recovered. As a result, only a small number of recovery transitions are needed to recover all the deadlock markings, i.e., the resulting net model with recovery transitions is live. Second, we develop another ILPP to find all recovery transitions at a time. The constraints of the ILPP ensure that every deadlock marking is recovered by at least one selected recovery transition and the objective function is used to minimize the number of selected recovery transitions. Then, a minimal number of recovery transitions are obtained by solving one ILPP only. Both approaches can make a net model live with all reachable markings. Finally, serval examples are provided to demonstrate the proposed approach.

Real-time work-in-progress management for smart object-enabled ubiquitous shop-floor environment

Recent developments in wireless technologies have created opportunities for developing next-generation manufacturing systems with real-time traceability, visibility and interoperability in shop-floor planning, execution and control. This article proposes a work-in-progress management framework based on smart objects such as radio frequency identification/Auto-ID devices and web service technologies in a ubiquitous manufacturing (UM) environment. Under this framework, two types of services (data source service and gateway data service) and WIPA (work-in-progress agent) are designed and developed to manage and control the real-time materials and information flows to improve the optimal planning and control of the entire shop floor. During production execution, real-time visibility explorers are provided for operators and supervisors to reflect the real-time situation of current manufacturing environment. It follows a simple but effective principle: what you see is what you do and what you do is what you see. Production disturbances could thus be detected and fed back to decision makers for implementing closed-loop shop-floor control. In addition, some important standards such as ISA 95 and business-to-manufacturing markup language (B2MML) are adopted to establish the information model and schemas of WIP called wipML (work-in-progress markup language). Based on B2MML and wipML, the real-time manufacturing information can be effectively encapsulated, shared and exchanged between gateways, WIPA and heterogeneous enterprise information systems. The presented framework is studied and demonstrated using a near real-life simplified shop floor that consists of typical manufacturing objects.

RFID-enabled product-service system for automotive part and accessory manufacturing alliances

Automotive part and accessory manufacturers (APAMs) at the lower tiers of automotive vertical supply chains have been responding to major initiatives taken by leading vehicle assemblers in adopting RFID (radio frequency identification) and ubiquitous computing technologies to alleviate their manufacturing systems. RFID-enabled real-time traceability and visibility facilitate and enhance the implementation of advanced strategies such as just-in-time (JIT) lean/responsive manufacturing and mass customisation (MC). This paper reports on findings gained from a series of industrial field and pilot studies conducted within collaborating companies. Being typically small and medium sized, APAMs are faced with business and technical challenges that are summarised by the so-called ‘three high problems’, namely high cost, high risk and high level of technical skills. This research takes a more cost-effective pragmatic approach to overcome the ‘three high problems’ by sharing out the problems among APAMs while taking a longer-term, expensive and lengthy, approach to absolutely reduce the problems. The sharing approach requires the establishment of an innovative service-oriented framework, abbreviated AUTOPS, based on the Product Service Systems (PSS) business model. RFID hardware devices are innovated into gateways as hardcore products to formulate a PSS. RFID-enabled real-time services are deployed at a common platform across members of an APAMs alliance. AUTOPS facilities are shared by APAM alliance members to reduce the start-up investment costs, reduce the level of required specialist skills, speed up installation processes and streamline maintenance services, and improve the reliability of the RFID gateway services.

A radio frequency identification-enabled real-time manufacturing execution system for one-of-a-kind production manufacturing: a case study in mould industry

One-of-a-Kind-Production (OKP) is a non-repetitive manufacturing mode that produces customised products with unique components. Due to the varying production requirements and inadequate operation experience, the unique components and related operations often causes great dynamics in the workshop execution process. Since most of the OKP companies currently adopt paper-based manual data transaction and report mechanism in workshop production process, such dynamics are hard to be timely detected and controlled, resulting in serious order delays and work-in-progress redundancies. Radio frequency identification (RFID) enables automatic and accurate object data capturing capability, and thus makes the real-time visibility and controllability possible to workshop execution process if combined with manufacturing execution system (MES). This article presents an easy-to-deploy and simple-to-use RFID-enabled MES to achieve such real-time control for typical OKP workshops. A real-life case study in a mold and die manufacturing company is presented to demonstrate how technical, social and organisational issues have been addressed in such project. A set of enabling technologies and systems that are key to the development of such RFID-enabled MES are introduced, including hardware like machine data terminal and workshop base station as well as software like scheduling and communication programmes. It is hoped that insights and lessons gained could be generalised for future efforts across small-and-medium-sized OKP manufacturers that share similar requirements.