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

Abstract

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.

Keywords:

• real-time
• ubiquitous manufacturing
• work in progress (WIP)
• agent
• RFID/Auto-ID; smart objects

Acknowledgements

The authors thank various companies who provided technical and financial supports to this research. They also acknowledge financial supports of HKSAR ITF (GHP/042/07LP) grant and National Science Foundation of China (50805116). This article has been presented at the DET2009 conference held at the University of Hong Kong during 14–16 December 2009 and was included in the conference proceedings published by Springer.