基于自动机的构件实时交互行为的形式化模型

采用形式化方法对复杂实时构件系统交互行为进行描述和验证,对于提高系统的正确性、可靠性等可信性质具有重要意义.分析了基于进程代数和自动机的构件交互行为形式化建模方法各自的优缺点,在此基础上提出了基于时间构件交互自动机的建模方法,给出了时间构件交互自动机的相关定义、组合和验证算法.时间构件交互自动机引入了时间限制、时间代价、时间代价计算半环、构件组合层次等概念,既能够描述构件交互情况,又能够清楚地表示出构件系统的体系结构信息和实时信息,便于对系统进行描述和验证.最后,结合具体应用给出了应用示例.     

基于构件的软件开发的方法与实践

随着软件工业的成熟以及对软件生产要求的不断提高,基于构件的软件开发作为一种新的软件开发方法被提了出来.该方法的开展通过集成已存在的构件进行,可以分为构件的评选、构件适配、构件组装、系统演化四个阶段.使用基于构件的软件开发能减少软件开发费用、提高软件开发速度等,但同时也可能带来一定的风险,因此,开发者在开发时应该遵循一定的原则,这些原则是在用该方法开发软件时总结出来的.     

基于SV2的汽车乘员约束系统仿真模型 可信度验证系统

针对汽车乘员约束系统仿真模型的可信度验证需要大量重复的数据处理和结果分析的问题,基于可信度验证系统（system of verification and validation, SV2）,将100%正碰、40%偏置碰和侧碰工况的分析流程固化,开发汽车乘员约束系统仿真模型可信度验证系统。对100%正碰工况进行试验验证,结果表明：新开发的仿真模型可信度验证系统对模型可信度验证能够提高90%的工作效率,自动生成分析报告,为仿真工程师提供模型改善建议。     

Assembly simulation of multi-branch cables

Cable assembly simulation is a key issue in the computer-aided design (CAD) of products with complex electrical components. In this study, an assembly simulation method is developed to simulate the assembly process of multi-branch cables. First, based on the Cosserat theory of elastic rods, a novel scheme is introduced to model the joints of multi-branch cables. The potential energy of joints is calculated by taking the topology and anatomical features into consideration. Various physical properties are considered. Various constraints, including connectors, collars, and handles are analyzed, based on which the initial conditions of assembly simulation are determined. The configuration of the cable is then calculated by minimizing its potential energy. To increase computational efficiency, GPU acceleration is introduced, which makes the simulation run at interactive rates even for a cable with resolution up to 1000 discrete points. Finally, the proposed algorithm is integrated into the commercial assembly simulation system, DELMIA. Several simulations were performed with our system. It was demonstrated that the proposed method is able to handle cables with complex topologies. In addition, the proposed method is about four times as efficient as a previous method, and it is able to generate realistic configurations of multi-branch cables at interactive rates. Thus, the proposed method is helpful in the assembly process planning of cables.     

基于混合模型的虚拟装配关键技术研究

针对虚拟装配中采用多边形网格模型引起的组件定位困难和碰撞检测精度低等问题,提出一种采用精确几何模型及其对应的多边形网格模型的混合模型作为底层数据,支持精确装配的虚拟装配系统构造方法,并基于Parasolid和Vir-tools平台进行了实现。基于混合模型的碰撞检测能根据计算精度和时间要求自适应求解,在速度快的同时,满足高精度碰撞检测要求;基于混合模型的组件装配,采用离散采样点定义装配路径,通过装配几何约束交互式定义限制组件的运动范围,通过自由度规约、装配约束求解实现了零部件精确定位,通过四元数插值实现装配路径中零部件位姿的平滑过渡,能满足高精度的装配要求。该方法已经在开发的多个系统中得到验证和应用。     

Practical verification of decision-making in agent-based autonomous systems

We present a verification methodology for analysing the decision-making component in agent-based hybrid systems. Traditionally hybrid automata have been used to both implement and verify such systems, but hybrid automata based modelling, programming and verification techniques scale poorly as the complexity of discrete decision-making increases making them unattractive in situations where complex logical reasoning is required. In the programming of complex systems it has, therefore, become common to separate out logical decision-making into a separate, discrete, component. However, verification techniques have failed to keep pace with this development. We are exploring agent-based logical components and have developed a model checking technique for such components which can then be composed with a separate analysis of the continuous part of the hybrid system. Among other things this allows program model checkers to be used to verify the actual implementation of the decision-making in hybrid autonomous systems.     

Model checking response times in Networked Automation Systems using jitter bounds

Response time (RT) of Networked Automation Systems (NAS) is affected by timing imperfections induced due to the network, computing and hardware components. Guaranteeing RT in the presence of such timing imperfections is essential for building dependable NAS, and to avoid costly upgrades after deployment in industries.This investigation proposes a methodology and work-flow that combines modelling, simulation, verification, experiments, and software tools to verify the RT of the NAS during the design, rather than after deployment. The RT evaluation work-flow has three phases: model building, modelling and verification. During the model building phase component reaction times are specified and their timing performance is measured by combining experiments with simulation. During the modelling phase, component based mathematical models that capture the network architecture and inter-connection are proposed. Composition of the component models gives the NAS model required for studying the RT performance on system level. Finally, in the verification step, the NAS formal models are abstracted as UPPAAL timed automata with their timing interfaces. To model timing interfaces, the action patterns, and their timing wrapper are proposed. The formal model of high level of abstraction is used to verify the total response time of the NAS where the reactions to be verified are specified using a subset of timed computation tree logic (TCTL) in UPPAAL model checker. The proposed approach is illustrated on an industrial steam boiler deployment.     

基于库存和在线生产的仓库发货配置方法

针对离散型加工装配企业不同订单复杂产品的零部件发货配置最优化问题,提出了一种全新的仓库发货配置方法. 它以按时交货和订单损失最小作为评价准则,以当前的生产状态为基础,找出当前产品加工和装配的工艺中余留最长的生产路线,并结合库存状态和订单的重要程度确定发货的优先程度,最终分别通过整单出厂和分步出厂两种发货模式实现了零部件的最优发货配置.     

基于工作流的电装行业MES关键技术研究

电子装配行业的特点要求电子装配行业MES系统实现实时可视化、动态生产排程、装配过程跟踪等功能,同时实现系统可配置、可重构、实时、可集成等.采用工作流技术,提出基于工作流的电子装配车间实时可视化、动态排程、生产过程跟踪模型;建立MES系统中工作流引擎的总体结构;并基于J2EE架构和EJB组件技术对工作流引擎进行设计实现.基于工作流的电子装配行业MES在某企业PCB装配车间应用表明,车间的生产效率和管理水平得到了显著提高.     

Block assembly planning in shipbuilding using case-based reasoning

A process planning system using case-based reasoning (CBR) is developed for block assembly in shipbuilding. A block assembly planning problem is modeled as a constraint satisfaction problem where the precedence relations between operations are considered constraints. In order to find similar cases, we propose two similarity coefficients for finding similar cases and for finding similar relations. Due to the limited number of operation types, the process planning system first matches the parts of the problem and those of the case-based on their roles in the assembly, and then it matches the relations related to the matched part–pairs. The parts involved in more operations are considered first. The process planning system is applied to simple examples for verification and comparison. An interface system is also developed for extracting information from CAD model, for preparing data for process planning, and for visually verifying the assembly sequence.     

Integration of the STEP-based assembly model and XML schema with the fuzzy analytic hierarchy process (FAHP) for muti-agent based assembly evaluation

Assemblability analysis and evaluation plays a key role in assembly design, operation analysis and planning. In this paper, we propose an integrated intelligent approach and framework for evaluation of assemblability and assembly sequence for electro-mechanical assemblies (EMAs). The approach integrates the STEP (STandard for the Exchange of Product model data, officially ISO 10303)-based assembly model and XML schema with the fuzzy analytic hierarchy process for assembly evaluation. The evaluation structure covers not only the geometric and physical characteristics of the assembly parts but also the assembly operation data necessary to assemble the parts. The realization of the integration system is implemented through a multi-agent framework. Through integration with the STEP-based product modeling agent system, CAD agent system and assembly planning agent system, the developed assembly evaluation agent system can effectively incorporate, exchange, and share concurrent engineering knowledge into the preliminary design process so as to provide users with suggestions for improving a design and also helping obtain better design ideas. The applications show that the proposed approach and system are feasible. Received: July 2004 / Accepted: January 2006     

Function block-based closed-loop adaptive machining for assembly interfaces of large-scale aircraft components

To guarantee the docking accuracy of large-scale components, their assembly interfaces usually need to be finished before the final assembly. However, there are some crucial problems affecting finishing efficiency and quality, e.g. use of hard-to-machine material at the assembly interface, manual interventions and process diversity in finish machining, difficulties in the alignment of the large component, as well as errors between the as-built and as-designed status of the large component. These problems significantly enhance the uncertainty in finish machining on a shop floor. To solve these problems, this paper proposes an approach of adaptive process planning and execution, i.e., IEC 61499 Function Block (FB) based Closed-Loop Adaptive Machining (CLAM). Thus, the adaptive alignment of the large component is achieved, which can guarantee the correct location between the assembly interface and the cutting tool. As well as the on-line CLAM of the assembly interface is also realized to improve the machining efficiency and quality. As a result, a FB based CLAM system for the assembly interfaces is established, which contains a CAD system, a FB enabled High-Level Controller (HLC), and several Low-Level Controllers (LLCs), as well as a mechanical system. The most notable is that the related FBs are designed to plan and execute the finishing process. Finally, the proposed method and system are validated by a large component from a real aviation industry, i.e., a vertical tail of a passenger aircraft. The experimental results indicate that the proposed method and system are feasible and effective to address the above-mentioned problems.     

构件系统建模及其动态演化一致性验证方法

基于构件的软件开发已成为软件开发的主流方法,但针对构件系统动态演化后的一致性保持问题,目前尚缺乏统一的标准,为此提出一种验证构件系统动态演化一致性的方法。首先,应用进程代数构造构件模型,并在此基础上得到粗粒度的构件系统模型;然后,根据构件系统模型及其状态的变化,提出构件系统外部行为提取算法,并基于弱互模拟理论定义构件系统动态演化一致性的验证准则;最后,提取演化前后构件系统的行为,并将其转换成便于Pi演算自动工具MWB(Mobility Workbench)识别的格式,以进行行为一致性验证。案例研究表明,该方法是可行且有效的。     

Developing test systems for multi-modules hardware designs

An approach aimed at creating test systems for complex hardware designs is proposed. The designs can be subdivided into modules and verified separately. The proposed architecture of separated verification systems and the way to combine them into a complex test system are based on simulation-based verification of hardware designs. Components of the test systems are connected in a TLM-like way (i.e., with the use of a high-level commutation model based on messages), which simplifies merging of several test systems into a test system for the entire complex component.     

A model based integration framework for computer numerical control system development

As a typical complex embedded computer control system, Computer Numerical Control (CNC) system development is confronted with a great challenge because of its specific requirements as well as some recent development trends such as ever more complex products while at lower prices and shorter develop cycle. In this paper, a model based integration framework (CNCMIF) for CNC system design and development is presented, which integrates modeling, simulation, verification and implementation in a uniform environment. The CNCML (CNC modeling language) with well defined syntax and unambiguous semantics is developed to describe the CNC system in an accurate and explicit way. Model transformation strategy for formal verification and code automatic generation for implementation in the framework are also presented. The approach is an attempt to create an infrastructure to support the CNC system design in an efficient way, while at the same time guarantees the function and performance requirements with advanced capability of the system such as modularity, flexibility, reusability, etc.     

复杂产品的VV&A体系架构关键技术

为开展复杂产品（系统）建模与仿真过程中的验证、确认与发布（verification, validation and accreditation, VV&A）工作,提高复杂产品(系统)的设计水平,保证和提高建模与仿真系统的置信度,降低试验与评估的不确定性,在分析复杂产品全生命周期中的VV&A活动的基础上,论述复杂产品（系统）的VV&A体系架构的复杂性及其关键技术,系统分析VV&A的主要思想和国内外研究与应用现状、VV&A工具和方法等问题,提出一种VV&A体系架构方案,并详细阐述其总体方案和系统组成,为逐步建设企业的VV&A知识库提供参考。     

Automatic generation of assembly dimension chain based on tolerance cell

In the process of generating assembly dimension chain automatically,there are many problems such as complex assembly relationship,variety of constraints of components and complex dimension and tolerance relations of components.These problems lead to many difficulties in search process and need lots of man-machine interaction.Because of these difficulties,this paper presents a method of automatic generation of assembly dimension chain based on tolerance cell.This method is realized through obtaining assembly tolerance cell and part tolerance cell first.These two types of tolerance cell are extracted and expressed in the form of linked list structure in computer further.Then assembly dimension chain is searched automatically based on obtained tolerance cell,and the correct assembly dimension chain is extracted finally.A system of generating assembly dimension chain automatically has been developed based on DELMIA and successfully deployed in aircraft assembly simulation in the engineering practice.     

C program verification in SPECTRUM multilanguage system

An extendable multilanguage analysis and verification system SPECTRUM is presented; this system is being developed in the framework of the project SPECTRUM. The prospects of the application of this system are demonstrated, as exemplified by the verification of C programs. The project SPECTRUM is aimed at the creation of a new integrated approach to the verification of imperative programs that makes it possible to integrate, unify, and combine methods and approaches for verification of imperative programs and accumulate and apply information about these programs. The specific feature of this approach is the application of a specialized executable specification language Atoment for the development of program verification tools; this language makes it possible to represent methods and approaches for verification and data for them (program models, annotations, logical formulae) in a unified format. The C component of the SPECTRUM system uses a two-level C program verification method. This method is a good illustration of the integrated approach, since it provides complex verification of C programs based on a combination of the operational, axiomatic, and transformational approaches.     

复杂机电产品中的柔性线缆装配过程仿真技术

针对复杂机电产品中柔性线缆结构复杂且在装配操作中发生变形而导致的装配过程仿真难的问题,系统地提出了柔性线缆装配过程仿真的解决方案及其关键技术的实现方法.首先提出一种基于元素包含关系和无向图的线缆数字化表达模型,实现了复杂线缆拓扑、几何和属性信息的统一表达,为装配过程仿真奠定了基础;然后提出一种改进的层次链装配过程模型,统一处理针对不同对象的装配任务和装配操作等,实现了装配过程中线缆和结构件交叉装配任务和装配操作的表达和存储;最后建立一种改进的线缆质点-弹簧模型,通过添加长度变化约束并设定典型装配操作中的约束条件,实现了线缆在装配仿真中柔性形变的实时仿真.在开发的原型系统中实现了柔性线缆的装配过程仿真,并通过实例验证了文中方法的可行性.     

Temporal logic programming for assembly sequence planning

A temporal-constraint logic programming framework for the specification and automatic verification and synthesis of assembly sequences is developed. The implemented tool is based on the formulated and derived precedence properties for a general mechanical assembly. This tool, called the Mechanical Assembly Sequence Satisfiability Checker (MASS-C), supports the use of a subset of temporal logic for assembly constraint specification. MASS-C provides the logic programming framework by which the designer can be relieved of the tedium of finding the assembly sequences, and the assembly sequence planning process manifests itself in the implicit modelling of assembly sequences by acquiring and formulating the set of correct and complete assembly constraints as a logic program. MASS-C implements a class of temporal expressions as predicates for logic programming of assembly constraints. It provides facilities to either verify an assembly sequence or synthesise all assembly sequences that satisfy the specified constraints composed as a logic program. Two examples illustrate the use of MASS-C for such verification and synthesis.