A geometrical approach to computer-aided process planning for computer-controlled machine tools

This paper documents part of a research program which has been under way at the CIM Centre at Swinburne University of Technology since 1989. The purpose of the research program was to develop an open-architecture machine tool control system and then to see how that system could be used to change the distribution of traditional manufacturing design, planning and control functions. This paper examines one part of that research program and focuses on a methodology which could prove to be useful in the machine tool selection, cutter selection and cutter path generation phases of process planning for cutting operations on workpieces in computer-controlled machine tools.It is suggested that a configuration space transform be used for each cutter/machine tool combination to find the volume that the combination could remove from the uncut workpiece without removing any of the material that will form the final workpiece. A method of comparing these volumes from different combinations is then outlined. The output of this method is a reasonable sequence of machine tools and cutters. Path planning can then be carried out for each of the chosen combinations using a method similar to the one used to find the possible volume to be removed.Possible implementation techniques, and their limitations on existing computer hardware, are discussed and the most promising of these are identified, based upon some properties of configuration space transforms.     

Application of DSP technology to closed-position-loop servo drive systems

The objective of this paper is to demonstrate how digital signal processor (DSP) technology can be applied to servo motor control in order to generate closed-position-loop servo drives that can be applied in advanced manufacturing technology applications such as robotics, CNC and other machine positioning systems.Neither the DSP nor intelligent servo controls are new technologies in their own right. However, it is the combination of the two which has been innovatively applied at the Swinburne University of Technology (Hawthorn, Victoria, Australia) in order to generate a system which has considerable potential in terms of redesigning computer controlled production equipment through a distributed control architecture. The resulting technology has been entitled CIM-Drive and has been commercialised by the Softronics company in Australia.The critical factor in designing an intelligent servo system is the provision of a real-time local area network that can be used for inter-servo communication and for supervisory control. A relatively simple networking scheme (entitled Softnet) was developed during the course of the research and is documented herein. A number of newer, commercially available alternatives such as the CAN-Bus, Field-Bus and LON bus are also highlighted in this paper to show the current development path being pursued at the CIM Centre.     

An Infrastructure for Integrated Automation System Implementation

Evolution of advanced manufacturing technologies and the new manufacturing paradigm has enriched the computer integrated manufacturing (CIM) methodology. The new advances have put more demands for CIM integration technology and associated supporting tools. One of these demands is to provide CIM systems with better software architecture, more flexible integration mechanisms, and powerful support platforms. In this paper, we present an integrating infrastructure for CIM implementation in manufacturing enterprises to form an integrated automation system. A research prototype of an integrating infrastructure has been developed for the development, integration, and operation of integrated CIM system. It is based on the client/server structure and employs object-oriented and agent technology. System openness, scalability, and maintenance are ensured by conforming to international standards and by using effective system design software and management tools.     

Development of a prototype customer-oriented virtual factory system

Current Computer integrated manufacturing/Enterprise Resource Planning (CIM/ERP) systems require harmony and communication between humans and facilities. A user’s preferences should also be considered in CIM/ERP systems. Virtual factory (VF), also known as virtual manufacturing (VM), systems can fulfill the requirements of current CIM/ERP systems. A VF system simulates virtual production in a virtual factory environment on the computer system which allows optimization prior to going into production. In this paper, we defined a VF system as a pre-analyzing system for designing, engineering and manufacturing a product in the enterprise system of the real world. The objective of this paper is to design a VF system and to develop a prototype system that the customer can participate in and be satisfied with. We selected a telephone as a sample product for the VF system. The VF system consists of four subsystems: virtual product ordering, design, manufacturing, and CIM/ERP interface. The prototype system aims to develop a virtual product ordering and design system.     

Development of a prototype customer-oriented virtual factory system

Current Computer integrated manufacturing/Enterprise Resource Planning (CIM/ERP) systems require harmony and communication between humans and facilities. A user’s preferences should also be considered in CIM/ERP systems. Virtual factory (VF), also known as virtual manufacturing (VM), systems can fulfill the requirements of current CIM/ERP systems. A VF system simulates virtual production in a virtual factory environment on the computer system which allows optimization prior to going into production. In this paper, we defined a VF system as a pre-analyzing system for designing, engineering and manufacturing a product in the enterprise system of the real world. The objective of this paper is to design a VF system and to develop a prototype system that the customer can participate in and be satisfied with. We selected a telephone as a sample product for the VF system. The VF system consists of four subsystems: virtual product ordering, design, manufacturing, and CIM/ERP interface. The prototype system aims to develop a virtual product ordering and design system.     

Automatic control of a One-of-a-Kind Production cell

This paper reports the outcome of a research project which aims to solve the problems in automatic control of the shop floor in One-of-a-Kind Production (OKP) through developing a prototype control system for an experimental OKP cell at the laboratory. The main problems in automatic control of the shop floor in OKP are the frequent changes of product structure or type and consequent changes of production system configuration. These changes in OKP make it necessary to have a highly flexible and robust automatic control system. To resolve the problems, a distributed control system has been developed at the CIM laboratory of the Department of Production, Aalborg University, Denmark. This control system has enough flexibility and robustness to cope with the aforementioned changes in OKP. To support the design and implementation of the control system, several concepts, algorithms and control principles, such as task logic routes, address code of production resources, automatic task decomposition algorithm, generic control modules and distributed control principles are also proposed in this paper.     

Incorporating CIM optimization in manufacturing management strategy

The objective of Computer Integrated Manufacturing (CIM) or the development of advanced manufacturing systems for a small to medium size company may not be total automation, but rather running a profitable business through improved product quality, improved design, reduction of inventory, shorter lead times and quick response to changes in the market demand. The implementation of the full range of Advanced Manufacturing Technologies (AMT) available to manufacturing industry would be expensive, risky and impractical. Management must find a way to make the transition from the current environment to one that includes several or all of the technologies of the factory of the future. The installation of new manufacturing systems or the modification of existing systems is a capital intensive operation that has been significantly influenced by computer control. As the complexity of the systems increases, so does the critical nature of cost effective alternative selection. In view of this intricately complex nature of most business systems, it has become increasingly difficult to evaluate new management concepts or system designs. Direct experimentation poses almost insurmountable problems due to disruptions, uncontrolled results, length of time required, and possibility of costly mistakes. Recognizing potential benefits and liabilities and measuring their significance is inherent to the usefulness of any CIM planning and implementation study. This paper describes progressive work carried out in constructing a strategy-based quantitative technique, which aims not only to formulate a strategy for CIM optimization (incorporating elements of a financial justification for the investment), but also identifies means of monitoring investment performance against strategy. The operational realization of such a strategy is discussed and illustrative examples are also presented.     

Performance management of manufacturing system networks

Performance management of communication networks is critical for speed, reliability, and flexibility of information exchange between different components, subsystems, and sectors (e.g., factory, engineering design, and administration) of production process organizations in the environment of computer integrated manufacturing (CIM). Essential to this distributed total manufacturing system is the integrated communications network over which the information leading to process interactions and plant management and control is exchanged. Such a network must be capable of handling heterogeneous traffic resulting from intermachine communications at the factory floor, CAD drawings, design specifications, and administrative information. The objective is to improve the efficiency in handling various types of messages, e.g., control signals, sensor data, and production orders, by on-line adjustment of the parameters of the network protocol.This paper presents a conceptual design, development, and implementation of a network performance management scheme for CIM applications including flexible manufacturing. The performance management algorithm is formulated using the concepts of: (1) Perturbation analysis of discrete event dynamic systems; (2) stochastic approximation; and (3) learning automata. The proposed concept for performance management can also serve as a general framework to assist design, operation, and management of flexible manufacturing systems.The performance management procedure has been tested via emulation on a network test bed that is based on the manufacturing automation protocol (MAP) which has been widely used for CIM networking. The conceptual design presented in this paper offers a step forward to bridging the gap between management standards and users' demands for efficient network operations since most standards such as ISO and IEEE address only the architecture, services, and interfaces for network management.This work was supported in part by National Science Foundation under Research Grant No. DDM-90-15173.     

Design of integrated manufacturing planning, scheduling and control systems: a new framework for automation

The automation and integration of manufacturing planning, scheduling and control functions have, for a long while, been targeted in computer-integrated manufacturing (CIM) and artificial intelligence (AI) approaches. Current systems, however, are human-based and they can only be characterised as decision support systems (DSS) rather than automated systems. Global competition and the need for improved responsiveness, particularly in low-volume, high-variety manufacturing industries, necessitate further integration and automation in planning, scheduling and control functions. We consider that, to achieve automation, the concepts and techniques from operations research (OR), control theory (CT), and computer science (CS) should be integrated, enriched and unified to provide a platform for automation. This paper presents a fresh perspective for understanding the design issues involved and proposes a new framework for the automation and integration of planning, scheduling and control functions. A fully automated flow shop production system is presented to illustrate the applicability of the new framework.     

PTA装置中重型压力离心机监控系统设计

针对重型压力离心机,给出了监控系统设计方案,提出了重型压力离心机数据采集和联锁保护的新方法.上位机选用DELL PC机,基于WindowsXP系统进行工程组态和工艺操作,下位机采用西门子PLC系统实现联锁控制,并成功应用在PTA装置上.     

机械设计专家系统的实现

专家系统(ES)技术是实现计算机集成制造系统(CIMS)的重要基础技术之一。本文从机械设计专家系统研究现状入手,分析了设计类专家系统的特点及困难;探讨了有关设计类专家系统的选题问题;介绍了我们CAD中心智能科研小组研制的八个专家系统的特点;最后,讨论了ES技术在机械设计中应用的研究方向。     

An investigation into the implementation of computer integrated manufacturing in small and medium enterprises

Small and medium enterprises (SMEs) play an increasingly important role in all aspects of competitiveness e.g. for both products and production techniques, but also management methods, the organisation of the firm and human resource training. Obtaining and, just as importantly, mastering scientific and technological information is therefore essential to competitiveness of all SMEs. During the last two decades, several factors have forced global manufacturers to make dramatic changes in their products, markets, and manufacturing strategies. One of the ways by which SMEs can achieve a competitive advantage in manufacturing is through the implementation of computer integrated manufacturing (CIM). Realising the importance of SMEs, an attempt has been made in this paper to study the implementation of CIM in SMEs. First, the characteristics of CIM have been studied with reference to the application and infrastructure of SMEs. Secondly, a framework has been presented for the implementation of CIM in SMEs with the help of a conceptual model. Finally, future research directions on CIM in SMEs are indicated.     

基于特征的回转类零件CNC／CAD／CAM集成系统开发研究

针对回转类零件的结构及加工特点，建立了基于特征的全局统一数据模型及在该模型上实现的回转类零件CAD／CAM集成系统的系统结构，以及以该模型为基础的设计制造支持软件体系，构造了基于工业PC机的开放式数控系统的控制软件和应用软件体系框架，并实现了基于开放式数控系统的回转类零件的集成化制造。     

Control and process-based optimisation of spot-welding in manufacturing systems

This paper documents a research program undertaken by the CIM Centre at the Industrial Research Institute Swinburne (IRIS) in collaboration with a major automotive manufacturer. The objective of the research was to examine potential mechanisms for improvement of the spot-welding process, which is a major component of automotive assembly. In particular, both traditional techniques for improving suboptimal parameters in the process and advanced techniques, based upon digital signal processor (DSP) control of the process (using acoustic-emission feedback), were applied to an industrial spot-welding test-case. This paper documents the outcomes of the two techniques and we demonstrate how significant improvements can be made to the overall spot-welding process through the adaptation of such technologies.     

Vision-based automated inspection system in computer integrated manufacturing

The industrial application of an automated inspection system that aims to enhance the efficiency and flexibility of a computer integrated manufacturing system (CIMS) is proposed in this paper. A machine-vision-based approach is adopted to utilise its advantages of measurement flexibility, high resolution, and non-destruction. With a closed-loop feedback control architecture, the inspection procedures are fully integrated with the production process to detect and to recover abnormal operations in a real-time mode. Implementation of such a system at a physical shop floor for socket inspection is presented as an example.     

计算机辅助监控机床颤振的研究

本文主要讨论机床颤振的计算机辅助监控问题。文中提出以特征量ξ做为机床颤振的监测参数,当ξ值超过预先设定的控制门限值时,计算机监测单元即向控制单元发出警报并采用一种特殊的变速控制策略抑制颤振于孕育之中。     

热力系统计算机监控实验台的研制

在现代工业热电厂中的大多数热力系统都采用了计算机控制系统,计算机控制系统对于机组的正常安全运行,提高机组的经济运行水平,减轻运行人员劳动强度等都具有明显效果。事实上许多大型热电机组的正常运转离开了计算机控制系统根本不可能。为了给热力系统计算机监控系统的研制和调试提供一种可靠的实验平台,开展新的控制算法和控制理论应用研究,我们在清华大学热力系统控制国家重点实验室开发了热力系统监控实验台。它采用世行贷     

喷气织机基于模块化结构微机控制技术

本文介绍了一种喷气织机的计算机控制系统的结构和原理，对研究其它计算机控制的织机具有一定的参考意义。     

基于单片机控制电子胸卡的设计

介绍一种以计算机和单片机为上-下位机结构的电子胸卡设计。通过上位机软件控制系统提取汉字点阵数据,发送显示控制命令。下位机由LPC900系列单片机和LED显示屏的硬件驱动电路构成,存储点阵数据和控制动态显示。上位机与下位机之间利用红外串行通信完成数据传输。该显示系统具有体积小,质量轻,功耗低和使用方便等特点。     

油压减振器试验用微机测控系统设计

介绍了一种用于铁路机车车辆油压减振器性能测试的新型试验设备，该设备采用计算机控制及交流变频调速。具有结构简单、试验精度高、可靠性好等特点，阐述微机测控系统的硬件与软件设计。