Optimal control of hybrid systems in manufacturing

Hybrid systems combine time-driven and event-driven dynamics. This is a natural framework for manufacturing processes: The physical characteristics of production parts undergo changes at various operations described by time-driven models, while the timing control of operations is described by event-driven models. Accordingly, in the framework we propose, manufactured parts are characterized by physical states (e.g. temperature, geometry) subject to time-driven dynamics and by temporal states (e.g., operation start and stop times) subject to event-driven dynamics. We first provide a tutorial introduction to this hybrid system framework and associated optimal control problems through a single-stage manufacturing process model. We then show how the structure of the problem can be exploited to decompose what is a hard nonsmooth, nonconvex optimization problem into a collection of simpler problems. Next, we present extensions to multistage manufacturing processes for which we develop solution algorithms that make use of Bezier approximation techniques. Emphasis is given to the issue of deriving solutions through efficient algorithms, and some explicit numerical results are included     

An extended unified framework for the rapid development of automated manufacturing systems

The design of today’s manufacturing systems involves the integration of specialised components with specific properties and functionality. Indeed, it has been a formidable task for the manufacturing community to develop a useable system economically with enhanced efficiency. In view of the technological advances in developing complex manufacturing systems, a unified framework had been proposed by the authors of this paper to formalise the procedures for the development of such systems. This paper presents an extension to this framework that automates the simulation of system behaviour at the design level. This extended framework incorporates a frame-based representation of the abstract classes that are generated from the unified framework, so that an expert system shell can be used to generate the expected behaviour of higher level designs prior to subsequent developments. The advantages of the extended framework include a shortened cycle for the product design and greater ease for system designers to produce manufacturing systems that better conform to their original specifications. A pharmaceutical system is chosen as a case example to illustrate the extended framework’s capability.     

Model-integrated mechatronics - toward a new paradigm in the development of manufacturing systems

The traditional approach for the development of manufacturing systems considers the constituent parts of the system, i.e., mechanical, electronic, and software, to be developed independently and then integrated to form the final system. This approach is being criticized as inappropriate for the complexity and the dynamics of today's systems. This paper proposes an architecture that promotes model integration not only for implementation space artifacts but also in artifacts of the early analysis and design phases of the development process. The proposed architecture, which promotes reuse and significantly decreases development and validation time, is at the heart of a new paradigm called model-integrated mechatronics (MIM). MIM applies domain-specific modeling languages for the concurrent engineering of mechanical, electronic and software components of mechatronic systems. It simplifies the integrated development process of manufacturing systems by using as basic construct the mechatronic component. The MIM paradigm was utilized to define "Archimedes," a system platform that supports the engineer through a methodology, a framework, and a set of tools to automate the development process of agile mechatronic manufacturing systems.     

Modeling, analysis, simulation, scheduling, and control ofsemiconductor manufacturing systems: A Petri net approach

This paper presents a Petri net approach to modeling, analysis, simulation, scheduling, and control of semiconductor manufacturing systems. These systems can be characterized as discrete event systems that exhibit sequential, concurrent, and conflicting relations among the events and operations. Their evolution is dynamic over time. The system complexity is tremendous owing to the complex semiconductor manufacturing processes and test procedures. A formal approach such as Petri nets enables one to describe such complex discrete event systems precisely and thus allows one to perform both qualitative and quantitative analysis, scheduling and discrete-event control of them. This paper also serves as a tutorial paper. It briefly reviews applications of Petri nets in semiconductor manufacturing automation. It then introduces definitions and concepts of Petri nets. It proceeds with a discussion of basic Petri net modules in system modeling, a modeling method and a practical system's modeling example. Next, the paper presents their properties and their implications in manufacturing systems, as well as their analysis methods. Timed Petri nets are introduced for system simulation, performance evaluation, and scheduling purposes. An application-oriented case study is presented. Finally, the paper concludes with the active research areas in applying Petri nets to design of semiconductor manufacturing systems     

The MMST computer-integrated manufacturing system framework

Computer-integrated manufacturing (CIM) is the harmonious connection, integration, and interoperation of automation equipment within a manufacturing facility. In a semiconductor wafer fab, this includes integration of the processing equipment with all of the supporting systems for product and process specification, production planning and scheduling, and material handling and tracking. Traditionally, CIM systems have been characterized as monolithic mainframe-based systems and/or inflexible islands of automation with limited interoperability. Today's manufacturing demands fully integrated dynamic systems which directly support the concepts of lean, flexible and agile manufacturing to high quality standards. These requirements drove the design of a new CIM system which was developed for the Microelectronics Manufacturing Science and Technology (MMST) program. This paper provides an overview of the MMST CIM system framework which is based on open distributed system and object technologies. The CIM system was demonstrated in a 1000 wafer pilot production run in 1993 which achieved world record cycle time, and is now being commercialized as part of the WORKS product family from Texas Instruments     

Applications of magnetic levitation-based micro-automation insemiconductor manufacturing

It is pointed out that the demands for precision and speed in manufacturing processes in the semiconductor industry are not well suited to traditional, large-scale approaches to automation. Consideration of several microautomation approaches has led to the development of a magnetic levitation-based system capable of three-dimensional motions. Such systems are able to move quickly and precisely, and can deliver prescribed forces and moments. Several significant applications of magnetic levitation-based microautomation in semiconductor manufacturing have been identified. These include positioning operations at various scales, such as mask alignment, hybrid circuit assembly, and transport between process stations. Other applications are analytical probing, nondestructive tape automated bonding (TAB) bond testing, and optical system alignment. A prototype system capable of high-speed four-degree-of-freedom motions with 0.5-μm accuracy over small workspaces has been demonstrated     

Foundations of data fusion for automation

This article discusses about the developing paradigms of data for sensor-actuator networks that perform engineering tasks. We provide a new foundation for data fusion based on two concepts: a conceptual framework and the goal-seeking paradigm. The conceptual framework emphasizes the dominant structures in the system. The goal-seeking paradigm is a mechanism for representing system evolution that explicitly manages uncertainty. The goal-seeking formulation for data fusion helps to distinguish between subjective decisions that can be executed by computers. These notions are useful for critical tasks, such as security management in large-scale distributed systems. Investigations in this area, and further refinement of the goal-seeking formulation for instrumentation and measurement applications, are likely to future systems that facilitate holistic user decision making.     

Distributed control of manufacturing cells in a Unix environment

The control of manufacturing cells plays a pivotal role in CIM, to provide inter-device communication and process control functionality. The recent availability of Unix systems for the high end PC market and the Intel 80386 and 80486 processors offers a range of new opportunities in shopfloor control. There are several reasons why Unix systems are suitable for the development of distributed control systems, primarily their support for communication networks and the recent availability of windowing systems for Unix.

This paper describes a control system developed to control an integrated manufacturing cell across an Ethernet LAN, under the AIX operating system. A graphical user interface was developed for the X Window System. The control software was written in C, on a modular basis, utilizing both AIX system calls and an interface to the X library of functions. The software, being both network transparent and device independent, allows control of the cell from any networked display terminal and demonstrates the suitability of a Unix environment as a tool, in the area of the distributed control of manufacturing operations.     

Virtual engineering: an integrated approach to agile manufacturing machinery design and control

A virtual manufacturing approach for designing, programming, testing, verifying and deploying control systems for agile modular manufacturing machinery are proposed in this paper. It introduces the concepts, operations, mechanisms and implementation techniques for integrating simulation environments and distributed control system environments so that the control logic programs that have been programmed and verified in the virtual environment can be seamlessly transferred to the distributed control system environment for controlling the real devices. The approach looks to exploit simulation in a much wider range of applications with great advantages in the design and development of manufacturing machine systems. In particular, it facilitates the verification of the runtime support applications using the simulation model before they are applied to the real system. Mechanisms that allow runtime data to be collected during operation of the real machinery to calibrate the simulation models are also proposed. The system implemented delivers a powerful set of software tools for realising agile modular manufacturing systems.     

Microsoft Office SharePoint Server在PCB制造企业中的应用与研究

随着信息化技术的不断提高,目前PCB制造企业信息化建设逐步发展到一定程度,他们中的大部分企业已经拥有了部分通用管理系统:如财务系统、HR系统、CRM等;还有部分个性化业务系统如ERP、消费系统等。这些应用系统在各自的业务领域发挥着重要的作用,但是对企业员工相关的信息不能集中共享,日常办公操作也是在不同的系统中切换查找。因此数据共享、协同办公,成为了企业提升办公效率的难题。利用Microsoft Office SharePointServer(简称MOSS)建立PCB协同办公系统提高企业规范化、实现管理落地。     

Tool spare management for a single manufacturing cell

This paper uses an L₁₈ orthogonal array design to study and analyze the tool spare management of a single manufacturing cell. The single manufacturing cell operates with two dissimilar workheads. A polynomial regression metamodel approach is developed for machine availability (average equipment utilization) and for the average server utilization. The models presented for these two performance measures are implemented in a decision framework to determine the optimum combinations of spare tools and repair levels. A numerical example is used to illustrate this important concept.     

A framework for building intelligent manufacturing systems

The paper describes a systematic approach to design and development of software for intelligent manufacturing systems. The approach is based on a multilevel, general object oriented model of intelligent systems. Current methods and software design and development tools for intelligent manufacturing systems either stress particular components of intelligence (e.g., high level domain expertise, or learning capabilities, or fuzziness of decisions), or their domain dependence (e.g., monitoring and control systems, or CAPP systems). It is usually difficult to make extensions of such methods and tools, nor is it easy to reuse their components in developing intelligent manufacturing systems. Considerable efforts are being dedicated to the development of interoperable software components, distributed object environments, and flexible and scalable applications to overcome some of these problems. The approach described in the paper starts with a well founded software engineering principle, making clear distinction between generic, low level intelligent software components, and domain-dependent, high level components of an intelligent manufacturing system. It is extensible and adjustable. It also suggests some steps toward design of future software development tools for intelligent manufacturing systems. Several intelligent systems have been developed using the approach. One of these systems, in the cement manufacturing domain, is briefly overviewed, illustrating how the approach is used in practice. Finally, some informal discussion on the performance and complexity of the approach is presented     

Development of a virtual metrology for high-mix TFT-LCD manufacturing processes

Nowadays,TFT-LCD manufacturing has become a very complex process,in which many different products being manufactured with many different tools.The ability to predict the quality of product in such a high-mix system is critical to developing and maintaining a high yield.In this paper,a statistical method is proposed for building a virtual metrology model from a number of products using a high-mix manufacturing process.Stepwise regression is used to select key variables that really affect the quality of th...     

A prototype SECS message service for communication in thesemiconductor manufacturing environment

The authors describe the SECS message service (SMS), a bidirectional protocol that can be used to transfer SECS formatted messages over an ISO-compatible network. SECS is the current protocol standard for communications in the semiconductor manufacturing manufacturing environment. SMS represents a first effort that provides for the migration of communication methodologies in the semiconductor manufacturing environment into the ISO arena. SMS incorporates desirable features of the SECS protocol into an OSI application layer environment, thus achieving advantages of both environments. The SMS protocol provides four services to the end user: MESSAGE provides for the transfer of SECS formatted messages, CONNECT provides for the establishment of virtual circuit connections between applications in a SMS ISO environment, DISCONNECT provides for the graceful ending of such operations in which no data are lost, and ABORT provides for the abrupt termination of such connections in which data may be lost. The SMS design process has produced the additional result of a methodology for incorporation of desirable features of a non-ISO protocol into an ISO-compatible system     

Fault diagnosis and computer integrated manufacturing systems

This paper examines one aspect of human interaction with computer-integrated systems, that of fault diagnosis or troubleshooting. The complexity (and attendant unreliability) of the new manufacturing systems has meant that fault diagnosis has become an increasing proportion and an integral part of operators' jobs. Establishing and maintaining high levels of diagnostic accuracy and efficiency is important for a variety of reasons. One is that equipment downtime is expensive, another is that errors of diagnosis might, under some circumstances, be a threat to both safety and quality. As yet there has been little research into human fault diagnosis in CIM. This paper draws on research from other industries, such as power generation and chemical production and explores the application of that work to fault-finding in computer-integrated discrete production systems. The focus is on the factors that influence individual fault-finding behaviors and efficiencies. Where possible, the aim is to identify critical human-machine interaction design principles and to highlight research questions yet to be addressed in contemporary manufacturing environments, with respect to the diagnosis of system failures     

Segment-based approach for real-time reactive rescheduling forautomatic manufacturing control

We propose a new segment-based approach for a real-time reactive rescheduling method. The approach is applicable to actual large-scale manufacturing systems, such as fully automated semiconductor wafer fabrication lines. The proposed method can efficiently (in terms of computation time) schedule processing operations at equipment units by dividing a wide scheduling range into small segments and by using a greedy scheduling algorithm. It can also reactivate infeasible schedules without sacrificing the quality of schedules in terms of productivity as much as possible. From the simulation results obtained, we experimentally confirmed that the proposed method reactivates, without significant productivity loss caused by the rescheduling algorithm itself, infeasible schedules faster than a comparative method commonly in use today. Consequently, the proposed method manages to keep schedules at each equipment unit executable in terms of processing performance and schedule quality     

Integration of task scheduling, action planning, and control inrobotic manufacturing systems

This paper presents a novel approach for solving a challenging problem in the intelligent control of robotic manufacturing systems, i.e., the integration of low-level system sensing and control with high-level system behavior and perception. First, a newly developed event-based planning and control method will be introduced. It will then be extended to a robotic manufacturing system via a hybrid system approach. The tasks of a robotic manufacturing system usually consist of multiple segments of robotic actions, which involve both continuous and discrete types of actions. The max-plus algebra model has been proposed to model such a system. Combined with the event-based planning and control methods, both discrete and continuous actions can be planned and controlled based on the max-plus algebra model. More important, the interactions between discrete and continuous actions can be formulated analytically. A typical parts-sorting task in a robotic manufacturing system is used to illustrate the proposed approach. The experimental results clearly demonstrate the advantages of this method