products quickly (supported with global customer service) in response to ... integrated design, manufacturing, and service business system. This set of core.
Internet Server Controller Based Intelligent Maintenance System for Products 1
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Chengliang Liu , Xuan F. Zha , Yubin Miao , Jay Lee
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1-Institute of Mechatronics Control, Shanghai Jiao Tong University Shanghai 200030, China; 2-National Institute of Standards and Technology, Gaithersburg, MD 20899,U.S.A.; 3-Center for Intelligent Maintenance, University of Wisconsin at Milwaukee Milwaukee, WI 53211, U.S.A
Abstract: This paper presents the development of an Internet server controller based intelligent maintenance system for products. It also discusses on how to develop products and manufacturing systems using Internet-based intelligent technologies and how to ensure the product quality, coordinate the activities, reduce costs and change maintenance practice from breakdown reaction to breakdown prevention. In the paper, an integrated approach using hardware and software agents (watchdog agent) is proposed to develop the Internet server controller based integrated intelligent maintenance system. The effectiveness of the proposed scheme is verified by developing a real system for the washing machine. Key words: e-Products, e-Manufacturing, e-Service, remote monitoring, diagnosis, maintenance, integrated intelligent systems, multi-agent system, neural computing, Internet, and WWW
1. Introduction In recent years, web-based e-system technologies have imposed the increasing impact on the evolution "velocity" for product design, manufacturing, and business operations. Business automation is forcing companies to shift operations from the traditional "factory integration" strategy into the "virtual factory" and supply-chain management strategy (NRC 1990). The technological advances to achieve this highly collaborative design and manufacturing environment are based on the multimedia type of information tools and highly reliable communication systems to enable distributed procedures in concurrent design, remote operation of manufacturing processes, and operation of distributed production systems. This transition is dependent upon the advancement of next-generation manufacturing practices on "e-factory and e-automation" focused on the use of information to
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support collaboration on a global basis. Quality is no longer a unique objective but a prerequisite for competition in the global marketplace. In addition, the complexity of today's products has greatly drawn consumer's attention on the service costs and values of the product's life cycle. A new robust paradigm focusing on e-intelligence for integrated product design, manufacturing, and service has be-come a new benchmark strategy for manufacturing companies to compete in the twenty-first century (Lee 1998, 1999, 2000). A leading manufacturing organization needs to be flexible in management and labor practices, and possess the ability to develop and produce virtually defect-free products quickly (supported with global customer service) in response to opportunities and needs of the changing world market. An e-Intelligence Maintenance System is needed for the next-generation product and manufacturing systems. Future smart manufacturing companies necessitate a set of core intelligence to address the issues of smart business performance within the integrated design, manufacturing, and service business system. This set of core intelligence is called "5Ps," namely predictability, producibility, productivity, pollution prevention, and performance. Scientifically, such kind of integrated business system is subject to the well-established prediction and optimization methods. In this case, with understanding of the manufacturing business, the focus should be on customer's solution and the optimum action should be found out for innovation in the product life cycle. The main objective of this research is to reduce the downtime of equipment near zero by: 1) developing an Internet-based server controller; 2) embodying a prognostics on-a-chip Watchdog Agent for product behavior assessment and performance degradation; 3) evaluating; 4) establishing a teleservice engineering system testbed (TEST); 5) developing integrated intelligent maintenance software system. This paper reports the development of an Internet server controller based intelligent maintenance system for information appliance products. A hybrid intelligent approach using hardware and software agents (watchdog agent) is proposed to develop the system. The organization of the paper is as follows. Section 2 provides the architecture of an intelligent maintenance system. Section 3 discusses a server controller used for the intelligent maintenance system. Section 4 develops and embodies a prognostics on-a-chip watchdog agent for assessing and evaluating product behavior and performance degradation. Section 5 is the discussion of the TEST and the development toolkit for the integrated intelligent maintenance software system. Section 6 gives some concluding remarks.
2. Intelligent Maintenance Systems To provide customers with better solutions, a sort of intelligent product service system should be developed, in which a smart software system can predict the failure of a product in advance. Such "prognostic" capability can provide a new kind of aftermarket service to guarantee product and operation performance. Thus, when developing products, the developer should realize that a customer's
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need should be extended to the whole lifecycle of a product, and this requires that product design should take into account aftermarket support. Service and maintenance are important practices to maintain product and process quality and customer satisfaction. Currently, many manufacturing companies are still performing service and maintenance activities based on a reactive approach. The fundamental issues for resolving these problems are inadequate information/understanding about the behaviors of products and manufacturing equipment on a daily basis. How to measure the performance degradation of components and machines is still an unsolved issue. Developers also lack the validated predictive models and tools that can tell what would happen when the process parameters take specified values. Research is required to understand the factors involved in product and machine breakdown and to develop smart and reconfigurable monitoring tools that reduce or eliminate the production downtime, and thus reduce the dimensional variation due to the process degradation. To achieve these goals, smart software and NetWare are needed to provide proactive maintenance capabilities such as performance degradation measurement, fault recovery, self-maintenance, and remote diagnostics. These features would allow manufacturing and process industries to develop proactive maintenance strategies to guarantee the product and process performance and ultimately eliminate unnecessary system breakdowns. When aging occurs, the component and machine generally progress through a series of degradation states before failure occurs. Fig.1 shows the architecture of an intelligent maintenance system. Develop new area for product
Send data about product performance Timing (Fault) Awake
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Fig. 1. Intelligent maintenance system The assessment of machine's performance information requires an integration of many different sensory devices and reasoning agents. The operational performance of components, machines, and processes can be divided into four states: 1) normal operation state, 2) degraded state, 3) maintenance state, and 4)
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failure state. If a degradation condition is detected, then proactive and corrective maintenance activities can be performed before a worse degradation condition or failure occurs. Fig.2 shows the process of products degradation. To achieve a just-in-time lean maintenance and service operation, better decision-making tools are required to strategize resources through a sup-ply-chain network system. Currently, many commercially available maintenance management software tools lack integration ability and interoperability with production control systems. They also lack values in managing maintenance logistics and service business. Companies need to perform remote maintenance decision making to support technical and business personnel in manage maintenance and service logistics activities. In addition, digital service modem can be used to integrate product's performance conditions with the customer support center via Internet. Normal run stage
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Fig. 2. Device time-performance curve
3. Internet-based Server Controller 3.1. Structure of the Embedded Network Model The server controller is web-enabled. An embedded network model is the core of the server-controller. Next-generation products are to be a B2D-based (BusinessTo-Device) global system, in which the server controller will be the base. Through the service controller, the service center can collect performance data and monitor all the products dispersed all over the world at any time. This requires that the networked products have an IP when it’s sold. The service center can also investigate the working states of any products and give the assessment results to the user. The Internet-based server controller has the following functions: 1) It’s a controller. 2) It's a web-enabled server, i.e., it can be connected to
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Internet/Intranet. The product can be controlled in the remote site. 3) It can monitor the equipment by collecting and processing the performance data and processing. Fig.3 shows the structure of the embedded network model composed of nine parts, including CPU, flash, RAM I/O, RJ-45, etc. In this model RTL8019 is used as the network controller and RABBIT2000 is used as the CPU. Fig.4 shows the photo of the server-controller (hardware).
Fig. 3. Structure of Server controller
Fig. 4. The photo of the server-controller (hardware)
3.2. Software Agent for Embedded Network Model The software of the embedded network model is a software agent in the system. It is used to coordinate and control the embedded network. Fig.5 shows the flowchart of the agent program in the network device in the remote monitoring system. The software agent is actually a package of Smart Prognostics
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Algorithms, which consists of embedded computational prognostic algorithms and a software toolbox for predicting degradation of devices and systems. A toolbox that consists of different prognostics tools has been developed for predicting the degradation or performance loss on devices, process, and systems. The algorithms include neural network based, time-series based, wavelet-based and hybrid joint time-frequency methods, etc. (Fig.6). The assessment of performance degradation is accomplished through several modules including processing of multiple sensory inputs, extraction of features relevant to description of product's performance, sensor fusion and performance assessment. Each of these modules is realized in several different ways to facilitate the use of software agent in a wide variety of products and applications. Various requirements and limitations with respect to the characteristics of signals, available processing power, memory and storage capabilities, etc. should be considered.
Fig. 5. The flowchart of the agent program for the network device
Fig. 6. Smart prognostics algorithms of software agent
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4. Watchdog Agent The Watchdog Agent integrated with wireless sensors provides integrated sensor acquisition, processing, hashing, and health (good condition) reporting. The Watchdog Agent performs multi-input data generalization, hashing and mapping, and represents the performance status information on a look-up table using a cerebellum computing approach. Fig.7 shows the computing scheme of the Watchdog Agent.
Fig. 7. Computing scheme of the Watchdog Agent
Fig. 8. The simplified hardware diagram of the Watchdog Fig.8 shows a simplified diagram of the assistant controller. From the diagram we can see that seven parts compose the controller: 1) MCU (8051): the CPU of the controller managing and controlling the actions of every part. 2) Reset circuit: makes 8051 to restore the original state. 3) Clock circuit: provides outside clock for 8051. 4) Control circuit: sends the control signals to start or stop the washing machine. 5) Signal collecting circuit: collects the primary signals through sensors. 6) Signal sending circuit: sends the results first to the web chip then to the monitoring module after the signal is processed in 8051.
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7) Signal receiving circuit: receives the control order from the webchip and then sends it to 8051.
5. Tele-Service Engineering System for Information Appliance and Testbed Information appliances and other interactive "beyond the desktop" products present some user interface design challenges. An information appliance involves a strong connection between the appliance and the network. Besides providing information it embodies the concept of e-home and e-service. Thus, an information appliance is a combo of 3C (communication, computer and consumed electric production). The user can get information over the network, control the operation mode of appliance in remote site, and obtain more services from the factory, not only its products. In a word, the user can obtain more comfort and pleasure. In this section, we discuss a teleservice engineering system testbed for information appliance (consumer appliance).
Fig. 9. Structure of the remote engineering system testbed
5.1. Structure of the Remote Engineering System Testbed We have developed a remote monitoring platform in which many instruments and devices can be monitored. In this paper, a washing machine is selected as an example of the monitoring object due to its universality and practicability. Fig.9 shows the structure of the remote engineering system testbed. The system consists of two parts. The first part is an assistant controller that receives control signals from the network device and controls the operation mode of washing machine. In the meanwhile, it receives sensory information from various sensors and sends to the network device after processing. The second part is the network device developed on the base of a web chip. This part acts as the tool that communicates with monitoring PC through Internet.
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Fig. 10. Remote Engineering System Testbed for Information Appliance
5.2. Main Interfaces of the Remote Engineering System Testbed Fig.10 shows a remote engineering system testbed for the washing machine. There are four buttons in this interface. “Start the washing machine” and “Stop the washing machine” can control the operation state of the washing machine. The user can view the running state of the washing machine through pressing the button “View the operation state of washing machine”. The last button “Home page” can make the user returning to the main homepage of the system.
5.3. The Development Toolkit In this work Dynamic C is used as the development toolkit. Dynamic C is an integrated development system for writing embedded software for Rabbit microprocessors. It provides many function libraries, all in source code. These libraries can help the user/customer to write the most reliable embedded control software.
6. Conclusions This paper presented the development of an Internet server controller based intelligent maintenance system for information appliance products (washing machine). It also discussed on how to develop products and manufacturing
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systems using Internet-based intelligent technologies and how to ensure product quality, coordinate activities, reduce costs and change maintenance practice from the breakdown reaction to prevention. The Internet server controller based intelligent maintenance system was developed using hardware and software agents (watchdog agent). A real intelligent maintenance system for the washing machine was developed to verify the effectiveness of the proposed approach.
Acknowledgement and Disclaimer We are happy with the help and support of Mr. Weiping Wu and Dr. Guoquan Zhao from UTRC. They give us the collaborating opportunities. This work is supported by the National Natural Science Foundation of China (Grant No.50128504). No approval or endorsement by the US National Institute of Standards and Technology is intended or implied.
References NRC (1990), National Research Council, The Competitiveness Edge: Research Priorities for U.S. Manufacturing, National Academy Press. Jack Welch and G E. (1996), Business Week, Oct. Issue Lee, J. and Kramer, B.M. (1992), Analysis of Machine Degradation Using a Neural Network Based Pattern Discrimination Model, J. Manufacturing Systems, Vol. 12, No. 3, pp. 379-387 Shi, J., Ni, J., and Lee, J. (1997), Research Challenges and Opportunities in Remote Diagnostics and System Performance Assessment, Proceeding of 4th IFAC Workshop on Intelligent Manufacturing Systems: IMS'97, July 21-23, Seoul, Korea. Lee, J. (1998), Teleservice Engineering in Manufacturing: Challenges and Opportunities, International Journal of Machine Tools & Manufacture, 38, p901-910. Lee, J. (1999), Machine Performance Assessment Methodology and Advanced Service Technologies, Report of Fourth Annual Symposium on Frontiers of Engineering, National Academy Press, pp.75-83, Washington, DC. Lee, J., and Wang, B. (1999), Computer-aided Maintenance: Methodologies and Practices, Kluwer Academic Publisher. Lee, J. (2000), E-Intelligence for Product and Manufacturing Innovation, Invited Special Lecture Paper, Proceeding of 7th CIRP International Symposium on Life Cycle Engineering, Tokyo Botkin, Jim. (1999), Smart Business, The Free Press Kurzweil, Ray (1999), The Age of Spiritual Machine, Penguin Books. Charan, R. and Tichy, N. (1998), Every Business is a Growth Business, Times Business.
