• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.39-42
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• 1995

A new methodology for representing the interaction between machines and the interlock signals required in FMCs has been developed. Object-Oriented Philosophies (OOPs) lend themselves to the development of such a scheme. A methodology developed here regards the tasks to be performed by the cell or any of its constituent machines for being primal. Sensory signals indicating the changes of state pf machines are used to trigger or initiate tasks. A task may be simple and require a relatively short time to execute, or may be complex and lengthy. This methodology may be depicated by a set of diagrams called Task Initiation Diagram (TID) and their accompanying rules.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.36-43
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• 1992

This paper presents a hierarchical real-time operation control and monitoring scheme of the FMS/CIM center which has been implemented at the Automation and Systems Research Institute of Seoul National University. The hierarchical structure of the whole scheme consists of three lavers. The upper layer is in charge of on-line scheduling, computer network control, shop-floor monitoring and command generation for AGV dispatching, machining, assembly, inspection, set-up, etc. The middle layer has six modules, which are installed in the FMS host computer with the upper layer and run on the multi-tasking basis. Each module is connected to one of six cell controllers distributed in the FMS model plant and transfers operation command down to each cell controller through the Ethernet/TCP-IP local area network. The lower layer is comprised of six cell control software modules for machining cell, assembly cell, inspection cell, set-up stations. AS/RS and AGV. Each cell controller reports the status of the manufacturing facilites to the middle layer as well as ecxecuting the appropriate sequence control of the manufacturing processes.

• Proceedings of the Korea Society for Simulation Conference
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• 1996.05a
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• pp.15-15
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• 1996

A shop floor control system (SFCS) is the central part of a CIM system used to control the activities of several pieces of manufacturing equipment (e.g., NC machines, robots, conveyors, AGVs, AS/RS). The SFCS receives orders and related process plans, and then performs selecting a specific process routing, allocating resources, scheduling the workpieces, downloading the processing instructions (e.g., RS-274 instructions for NC machines, VAL II programs for robot), monitoring the progress of activities, detecting and recovering from errors, and preparing reports on the status of the manufacturing system. Simulation has been utilized in discovering control policies used for resolving shop floor be control problems such as resource contentions, part dispatching, deadlock. The simulation model must be designed to respond to real-time data coming from a shop floor. However, to rapidly build a realtime simulation model of SFCS cannot be easily accomplished. This talk is to address an automatic program generator of discrete event simulation model for shop floor control from process plans and resource models. The program generator is capable of constructing complete discrete simulation models for multi-product and multi-stage flexible manufacturing systems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.33
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• pp.63-70
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• 1995

Most of small-to-medium sized companies use computer to manage and control their manufacturing system. However, it is real hard to find a company which uses the system properly. There are several reasons. First of all, appropriate software to satisfy user's needs is not available and there is lack of mind to computerize. Therefore, this paper focuses to show difficulties which they will encounter, develop a model of computerized production management system and define proper level of computerization. An experimental system has been developed for an auto-parts manufacturing company using IBM-PC in the environment of MS-DOS and CA-Clipper.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.4
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• pp.88-99
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• 1995

The demand for automatic manufacturing systems is increasing. Flexible Manufacturing System(FMS) is usually considered as a soluting for the shop floor automation. One of the difficulties in FMS is the communications problem. Since various machineries with different communications protocoles are included, applying a unified scheme is almost impossible. Therefore, a systematic approach is a key point to solve the communication problem. A cell is difined as an automation unit where closely related for a job reside together. A cell is a messenger between upper level computers and lower level machine equipment. In this research, the fonctions of the cell are defined to have more capabilities than conventional cells since a cell can be often a total manufacturing system is a small to medium sized factory. The cell conducts communications with different machines through the communications schemes established here. A set of software system has been developed according to the defined communication. The software has been tested for a simulation and real experiments for proof.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.108-118
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• 1997

The heterarchical structure provides a more attractive solution to the conventional hierarchical structure as the density and level of distrubution of computing resources in manufacturing system expands. Tracing the evolution of control structures for automated manufacturing systems, this paper discusses the design principles for heterarchical system to reduce complexity, increase extendability, flexible configurability and suggests a good example of real-time adaptation using the concept of intelligent agent of manufac- turing entities and fault diagmosis system.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1720-1730
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• 2005

Automatic guided vehicle in the factory has an important role to advance the flexible manufacturing system. In this paper, we propose a novel object-transportation control algorithm of cooperative AGV systems to apply decentralized control to multiple AGV systems. Each AGV system is under nonholonomic constraints and conveys a common object-transportation in a horizontal plain. Moreover it is shown that cooperative robot systems ensure stability and the velocities of augmented systems convergence to a scaled multiple of each desired velocity field for cooperative AGV systems. Finally, the application of proposed virtual passivity-based decentralized control algorithm via system augmentation is applied to trace a circle. Finally, the simulation and experimental results for the object-transportation by two AGV systems illustrates the validity of the proposed virtual-passivity decentralized control algorithm.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.1
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• pp.119-135
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• 1995

We consider problems of tool loading and scheduling in a flexible manufacturing system (FMS) in which tool transportation constitutes the major portion of material flows. In this type of FMSs, parts are initially assigned to machines and released to the machines according to input sequencing rules. Operations for the parts released to the machines are performed by tools initially loaded onto the machines or provided by an automatic tool transport robot when needed. For an efficient operation of such systems, therefore, we may have to consider loading and scheduling problems for tools in addition to those for parts. In this paper, we consider three problems, part loading, tool loading, and tool scheduling problems with the overall objective of minimizing the makespan. The part loading problem is solved by a method similar to that for the bin packing problem and then a heuristic based on the frequency of tool usage is applied for tool loading. Also suggested are part input sequencing and tool scheduling rules. To show the effectiveness of the overall algorithm suggested here, we compare it with an existing algorithm through a series of computational tests on randomly generated test problems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.15 no.26
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• pp.43-48
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• 1992

국제적으로 증가되어지고 있는 제조업분야의 경쟁으로 인하여 사업체들 간에는 경쟁적으로 이상적인 방법의 공장자동화 (Factory Automation)를 품질향상 및 생산성증가를 위한 한 방법으로 채택하고 있다. 치열해지는 경쟁력으로부터 시장을 고수하기 위해 공장자동화가 기업들 간에는 근본대책으로 설정되고 있는데, 이러한 경향은 사업체들이 보다 나은 품질의 제품을 저렴한 가격으로 소비자에게 제공하고 생산력향상을 경제적으로 달성하기 위하여 많은 액수의 비용을 투자하게끔 하고 있다. 현재 여러 종류의 공장자동화 방법이 개발되고 있고, 채택되어지고 있다. 그 중에서도 현재 많은 각광을 받고있는 분야가 유동제조시스템(Flexible Manufacturing System ; FMS)이다. 본 연구에서는 유동제조시스템을 공장자동화의 한 방법으로 채택하기 위해 필요한 기본적인 두 가지 요소, 정당화 및 계획과정에 관하여 논하였다. 우선적으로 정당화되어야 할 문제점들 중에는: 1) 유동성에 대한 이해와 경제성에 대한 연구, 그리고 2) 노사관계에 관한 문제점들을 고찰하여 각 기업의 특성에 맞게 조절을 해야한다. 이러한 점들에 대한 이해, 연구, 고찰이 이루어지고 정당성이 성립이된 후에는 유동제조시스템을 점차적으로 정착시킨다. 이 진행과정에서 성립되어야 할 점들은 다음과 같다. 첫째, 시스템 채택방법을 택하고, 둘째, 분임조를 결성시켜 설정되어진 과제들을 분담하여 해결해 나아가면서 유동제조시스템이 하나의 고유적인 방법으로 회사의 특색 및 실정에 맞게 정착되도록 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.605-606
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• 2006

Today, the need for more flexible and adaptive production system and integrated management of their manufacturing information and facilities is ever increasing to cope with competitive and ever-changing global market environments and complexity of new control systems. This paper presents the whole system architecture and the technological characteristics of for each individual system layer which are able to flexibly integrate and manage high-speed and high-precision machining systems. It is investigated that monitoring and integrated management of the control systems can be realized with consideration of detailed information of various CNCs, and the management function may be easily constructed and extended using components of the manufacturing execution layer.