基于STEP-NC车削仿真的关键技术探讨

基于STEP-NC的智能化数控系统开发的一部分,以车削仿真为研究对象,重点探讨了STEP-NC车削数控系统中仿真模块实现的几个关键技术,为STEP-NC车削数控系统智能化的实现提供了一定的理论依据.     

高性能数控系统解释技术的研究与实现

针对高性能数控系统中解释器面临的要求,通过深入分析现有数控系统中解释器及与之交互的任务控制器的主要功能及实现方法,指出其在高速高精加工时存在的不足,在此基础上设计并实现了一种高效的NC代码解释机制;然后,对现有数控系统进行了基于STEP-NC的改造,提出了面向网络化制造STEP-NC数控系统的基本框架,并重点介绍了基于XML的STEP-NC程序解释器的设计与实现.     

基于XML的STEP-NC程序解释器的设计与实现

通过分析STEP-NC数据模型及程序结构,指出ISO10303 Part21物理文件格式数控程序不适合在网络上传输的缺点.因而在对现有数控系统进行基于STEP-NC的改造时,采用XML作为STEP-NC数控程序的文件格式,并提出面向网络化制造STEP-NC数控系统的基本框架,阐述了各组成模块的功能.同时从教据存储结构、解析XML、信息提取方法三个方面重点介绍基于XML的STEP-NC程序解释器的设计.最后采用JAVA语言实现了该解释器的功能,并通过STEP.NC标准草案里的一个实例验证该设计的正确性.     

基于多核ARM的数控系统实时性研究

随着数控系统的不断发展,数控系统对精度和速度有了更高的要求,这都对当前普遍采用的单核处理器平台提出了严峻的挑战.基于同构的四核ARM处理器平台,在添加了实时补丁的Linux系统环境下,根据数控系统中硬实时任务、软实时任务、非实时任务并存的特点,把数控系统任务合理的分配到多核ARM上运行,并采用改进的RM算法进行调度,最后对新的任务调度算法进行实时性能测试.本调度模型能够解决了数控系统混合任务调度的问题,并能满足数控系统对实时性的要求.     

面向STEP-NC的数据处理与仿真平台研发

介绍了STEP-NC数据模型的基本特点，分析了数控程序中的信息类型，研究了从STEP-NC文件中直接提取制造信息的基本方法，建立了基于特征的数控加工几何仿真模型，并讨论了相应的实现方法和技术。最后在ST-Developer环境下开发了一个基本的STEP-NC支持平台，其基本功能包括STEP-NC文件的翻译、制造信息的提取、组织和图形化显示等，并能以工步为单位进行仿真。     

基于RTAI的数控系统跟踪调试模型的设计与实现

为了丰富数控系统的调试手段,本文在RTAI进程间通信和环形缓冲区技术的基础上,提出一种基于RTAI的数控系统实时任务跟踪调试模型.该模型实现了动态地对数控系统中的实时任务进行跟踪,获取有效的调试信息,并在进行跟踪时对实时任务的性能影响尽量小,而在不跟踪时对实时任务几乎没有性能影响.该模型已在我们开发的数控系统调试工具中得到实际应用.     

基于实时组件的可重构数控系统研究

针对可重构数控系统存在的行为与定时问题，将调度机制引入基于口的组件，提出一种实时组件模型，并以此为基础建立了层次化多模式的数控系统体系结构。该结构通过层次化有限自动机描述系统的控制行为；通过组件网络刻画系统的定时特性，为分析可重构控制器构形的变化提供了有效的手段。针对2轴控制器的重构过程有效地验证了文中方法的有效性。     

实时Linux数控系统的研究和应用开发

分析了通用Linux系统到实时Linux的改造,以及它们的体系结构,它们的区别和通用Linux在实时控制中的缺陷,讨论了数控系统的软件体系结构和数控软件的多任务模型,数控软件在实时Linux上的开发。从实时Linux系统软件的理论和应用开发的详细论叙,为实时Linux系统下数控软件的开发和实现提供了很好的参考模型,方法和理论依据。     

基于信息流的实时电子商务推荐策略

针对企业对实时个性化推荐的需求,基于信息流的表达、生成和分析对顾客访问记录进行了深层次挖掘,研究了电子商务系统实时个性化推荐策略。提出了包含信息流定义、信息流评价、知识匹配、网站动态组织等算法在内的个性化推荐算法。基于J2EE技术完成了包含客户端、服务器端和存储系统在内的实时动态个性化推荐系统的结构设计。实例表明,随着训练次数的增加推荐准确度呈升高的趋势,并优于关联规则法。     

嵌入式数控系统模型层验证设计策略研究

在分析传统嵌入式数控的开发方法上的不足,以及目前对其开发方法的诸多变革的基础上,提出并实现将特定领域模型驱动开发融入到嵌入式数控系统的开发,构建了嵌入式数控系统模型层验证框架.该方法为嵌入式数控系统的开发提升了相应的抽象层次,提高了模型在系统开发中的作用,并利于提高系统的可操作性、可靠性、开发效率.通过对数控系统不同工作模式在第三方工具(StateFlow)的仿真实例,详述了该方法在特定领域建模语言的构建、模型转换的实现等方面的细节,并给出了转换后的对应StateFlow模型图.     

A STEP-compliant process planning system for CNC turning operations

Over the last 50 years, there have been many significant enhancements in computer aided systems which have influenced the CNC technology. One area that can be considered as a bottleneck to these CNC enhancements, and in particular to interoperability in CNC manufacturing is G&M part programming (ISO 6983). To overcome this bottleneck, the new standard ISO 14649, known as STEP-NC, is being developed to provide detailed information on component design, process planning and machining strategies to manufacture parts for the next generation of intelligent CNCs. This standard forms the basis of a new paradigm shift in the CNC domain to support digital modelling of CNC manufacturing resources. The research in this paper aims to identify major issues and develop new software tools to demonstrate the feasibility of interoperable CNC manufacturing based on STEP-NC. Besides the literature review on recent research and development on STEP-NC, this paper proposes a Process Planning System (PPS) with surface roughness chosen as the process planning objective. PPS consists of five modules: program reader, process planner, STEP-NC CAD viewer, STEP-NC CAM viewer and program writer. The reader is responsible for interpreting the geometry and the manufacturing data from a STEP-NC text file into a stored data list. The process planner uses this data list and enables users to evaluate surface roughness based on a mathematical model. Through the STEP-NC CAD viewer, the part geometry can be shown and via the STEP-NC CAM viewer the toolpath can be verified. Finally, the writer converts the stored STEP-NC data of the system into an updated STEP-NC file. An example case study component is used to demonstrate the PPS and show the interfacing of the STEP-NC data.     

STEP-NC compliant process planning as an enabler for adaptive global manufacturing

Manufacturing firms are seeking more efficient methods of CNC manufacture. ISO14649 informally known as STEP-NC has been proposed as a high-level hierarchical manufacturing information model as a replacement for the low-level machining instructions of ISO6983 and RS274D. In this paper, the applicability of STEP-NC as an enabler for creating an adaptive global manufacturing system is examined. The overall framework of the system is presented followed by an outline of its information requirements. Suitability of STEP-NC to support each requirement is then studied with the necessary additions highlighted. Finally, a test component is used in conjunction with a prototype of the advanced global manufacturing system to demonstrate the applicability of the STEP-NC standard to support manufacturing information in such a system.     

Realization of STEP-NC enabled machining

A STEP-compliant CNC machine tool that demonstrated a G-code free machining scenario is presented. The aim of this research is to showcase the advantages of, and evaluate, STEP-NC—a new NC data model—by implementing it in a legacy CNC system. The work consists of two parts: retrofitting an existing CNC machine and the development of a STEP-compliant NC Converter called STEPcNC. The CompuCam's motion control system is used for retrofitting the machine, which is programmable using its own motion control language—6K Motion Control language and capable of interfacing with other CAPP/CAM programs through languages such as Visual Basic, Visual C++ and Delphi. STEPcNC can understand and process STEP-NC codes, and interface with the CNC controller through a Human Machine Interface. It makes use of STEP-NC information such as “Workplan”, “Workingstep”, machining strategy, machining features and cutting tools that is present in a STEP-NC file. Hence, the system is truly feature-based. The Application Interpreted Model of STEP-NC has been used.     

An advanced STEP-NC controller for intelligent machining processes

Major improvements in high speed machining technologies are not followed by suitable evolutions of the programming standard ISO 6983, also called G-code. New STEP-NC standard aims at performing high level intelligent NC programming adapted to modern machining issues. The integration of manufacturing level in the numerical chain CAD–CAM–Simulation–CNC allows the implementation of a unique file gathering of all the needed information of a part that is directly machined without post-processing. In this paper, the authors show the new possibilities in terms of the following criteria: integrating simulation and optimization of the machining parameters, providing feedback to CNC controller, allowing modifications of the geometry and machining parameters on the CNC, computing new algorithms for tool-paths generation, adaptation to machine structure and characteristics, etc. A STEP-NC interface has been developed for CNC machine tools. It enables parts machining from a STEP-NC file and integrates several new possibilities and opens the way of intelligent high level programming including the machine model and an adaptation to machining real conditions.     

STEP-NC based high-level machining simulations integrated with CAD/CAPP/CAM

With the development of manufacturing,numerical control(NC) machining simulation has become a modern tool to obtain safe and reliable machining operations.Although some research and commercial software about NC machining simulations is available,most of them is oriented for G&M code.It is a low-level data model for computer numerical control(CNC),which has inherent drawbacks such as incomplete data and lack of accuracy.These limitations hinder the development of a real simulation system.Whereas,standard for the exchange of product data-compliant numerical control(STEP-NC) is a new and high-level data model for CNC.It provides rich information for CNC machine tools,which creates the condition for an informative and real simulation.Therefore,this paper proposes STEP-NC based high-level NC machining simulations solution integrated with computer-aided design/computeraided process planning/computer-aided manufacturing(CAD/CAPP/CAM).It turned out that the research provides a better informed simulation environment and promotes the development of modern manufacturing.     

Reincarnation of G-code based part programs into STEP-NC for turning applications

As STEP-NC emerges as the new CNC control method and a fundamental means for realizing e-manufacturing, old manufacturing information based on the conventional manufacturing standard will become obsolete. In practice, replacement of G-code based part programs into STEP-NC is a huge task. In this paper, methods to interpret G-code based part programs into STEP-NC code are investigated. G-code is a compact, coded set of numbers for axis movements, while STEP-NC is very comprehensive and includes information about features, operations, strategies, cutting tools, and so on. It is thus very challenging to derive such comprehensive information from the low level G-code information. In this paper, we first clarify what should be given and what may be given, and then present algorithms for deriving STEP-NC information, such as geometric features, operations, etc., from the tool movement (G-code) based on expert reasoning. The algorithms are developed for the turning application. The developed algorithms were implemented and tested on G-code part programs used in actual practice.     

STEP-compliant CNC system for turning: Data model, architecture, and implementation

STEP-NC, a new data model for CAD-CAM-CNC chain, is expected to encompass the whole scope of e-manufacturing. The new data model formalized as ISO 14649 is under development by ISO TC184 SC1 and SC4 for the replacement of the old standard so-called G&M codes, formalized as ISO 6983 which has been used since the 1950s. As the new data model is being established, development and implementation of STEP-compliant CAD/CAM/CNC system based on the new data model is drawing worldwide attention. Several systems have been reported in such international conventions as the ISO Expert Committee Meeting. Up to the present time, all the STEP-CNC systems are intended for milling operation. In this paper, the authors first present STEP-compliant CNC system for turning system including the data model, followed by a generic architecture and functionality. Implementation results obtained from a prototype system called TurnSTEP have been provided. Based on the results, the authors are convinced of the validity of the STEP-NC data model together with the effectiveness of the STEP-CNC system for turning.     

Modelling and implementing circular sawblade stone cutting processes in STEP-NC

The paper presents a STEP-NC compliant implementation of circular sawblade stone cutting machining processes. Although some stone machining processes has been already covered in the STEP-NC research and standardization initiatives (as for instance stone machining through stone milling machines), there have not been yet, however, any detailed model proposal to cover circular sawblade stone cutting operations. Sawblade cutting technology for stone parts have several specific parameters with no clear equivalent technologies as defined in milling, turning, etc. The paper reviews main characteristics of the circular sawblade stone cutting machining operations, and proposes a STEP-NC extended model based on the selection and definition of new features and on the modelling of these stone cutting operations. The resulting model is the base for the development of the STEP-NC stone cutting CAM and CNC machine. The machine architecture is designed to be able to react to changes in the machining conditions, very common in this technology. The system is based on the definition of features to be communicated to the controller. The controller has the objective of machining the features, and it is able to re planning, on real time, the work to get them despite changing conditions in the stone or in the disc.     

基于STEP-NC的CNC系统中NURBS插补技术研究

STEP-NC是一个用来实现CAD/CAM与CNC系统间数据交换的接口标准,基于STEP-NC的CNC系统是未来数控技术发展方向之一,该系统不但具有直线和圆弧插补功能,而且还具有样条曲线插补功能。为此设计了一个统一的基于NURBS样条曲线插补的通用插补器,并开发了一种基于等弧长的插补技术和插补算法。最后通过仿真和实例加工验证了该算法的有效性和可靠性。