信息-物理融合系统动态行为模型构建方法

信息-物理融合系统(Cyber-Physical System,CPS)特有的计算、通信、控制的联合动态性,计算与物理的多尺度融合性,系统环境及状态的时空交互性以及系统动态行为的非确定性,不但使面向CPS的模型驱动设计与验证方法在CPS系统设计中更为重要,而且也向其提出了新的技术挑战.论文在结合典型实例分析CPS系统特征及其模型构建具体挑战的基础上,研究并总结了CPS动态行为建模的主要方法:一体化建模方法从CPS系统层面描述计算过程与物理过程的交互与融合;时空交互建模方法关注CPS系统行为与时间及空间关系的语义表示;功能和实现兼容建模方法侧重刻画CPS系统的逻辑设计和物理实现的映射与支撑;而集成建模方法则重点解决多异构模型的交互方式与语义的一致表达.论文基于多异构实体的CPS系统建模框架,提出了一种CPS系统结构与动态行为的协同建模方法,并用CPS-ADL对其进行了实现和验证.     

基于扩展DPN的CPS混成行为时效建模与综合评估

信息物理融合系统行为是一种由离散计算过程与连续物理动态过程深度融合并紧密交互的混成行为.在CPS设计早期对信息系统实体的信息实体的关键监控参数、实时指标,以及物理系统设施的连续行为规律进行综合评估,是这类系统进一步设计与实现的基础.基于扩展DPN语义,以某智能车CPS系统自主行进紧急避障过程为研究对象,建立了其信息物理混成行为的Petri网模型,以融合并集中体现各关键参数和指标的时序协作效应;通过对该模型的仿真运行,实现了CPS行为的在线观测与综合评估.该方法为CPS子系统关键设计指标的综合合理性评估及其组合设计提供了一种解决途径.     

基于扩展混成Petri网的CPS无人车系统建模与分析

信息物理融合系统(Cyber-Physical System,CPS)是一个集计算系统、通信系统、感知系统、控制系统和物理系统于一体的复杂系统,其行为是一种由离散计算过程与连续物理过程深度融合并紧密交互的混成行为。针对这种特性,采用混成Petri网对CPS建模,并在此基础上添加时间约束,即对离散变迁关联一个延迟时间,对连续变迁关联一个激发速率函数,同时引入抑止弧和测试弧的概念以提高Petri网的表达能力,由此提出一种新的模型——扩展混成Petri网模型。然后,对CPS应用中无人驾驶车辆系统的躲避障碍物场景进行建模,将建立的模型按照一定的规则转化为与之对应的Simulink模型,并通过Matlab仿真对系统行为及属性进行分析。     

信息物理系统软件设计自动化专题前言

为了更精确地认识与改造世界，新一代的嵌入式系统必须将计算世界与物理世界作为紧密交互的整体进行认知，实现集计算、通信与控制于一体的深度融合的理论体系与技术框架，即信息物理系统（cyber-physical systems，简称CPS）.与传统嵌入式系统不同，CPS充分考虑了计算部件与物理环境的深度融合，通过将设备智能化连接，实现物理环境系统与计算系统之间精确感知与高效协同.基于CPS理念设计出来的计算设备可以根据具体任务需求自适应地调整与配置计算逻辑，精确智能地获取外部物理环境信息并做出针对性的实时反应，完成安全可靠的控制服务，从而实现物理世界与信息世界的有机统一.
随着人们对信息技术质量要求的不断提高，CPS迅速在众多安全攸关领域得以部署承担关键任务.从远程精准医疗到智能轨道交通，从无人驾驶到航空航天，从智慧城市到智能制造，无处不见CPS的身影.虽然CPS在众多领域获得成功，然而由于其涉及多维时空约束、异构物理/计算进程交互、运行环境不确定等因素，CPS设计复杂度极高.在缺乏设计自动化方法与技术的情况下，CPS开发周期长且质量难于保证.日益复杂的CPS设计与实现在给产业界与学术界带来巨大挑战的同时，也创造了大量新的机遇，CPS设计自动化目前已成为国际相关研究领域的关注与研究热点.
本专题采取自由投稿的方式，共收到14篇投稿.特约编辑邀请了30余位领域专家参与审稿，每篇稿件至少邀请3位专家进行评审，每篇录用稿件都经过至少3轮审稿.14篇稿件中共计10篇稿件通过第1轮评审，8篇稿件通过第2轮评审，并在CCF软件工程专业委员会、系统软件专业委员会年会全国软件与应用学术会议NASAC2019会议上进行了报告.经过第3轮终审及少数稿件的第4轮复审后，最终有6篇论文入选本专题.
《基于SHML的CPS行为建模及仿真》提出了一种面向CPS领域的建模及仿真方法，设计并实现了一个集成的面向CPS行为的建模与仿真平台，为CPS的建模及仿真提供了一种有效的方法及工具支撑.
《垂悬指针检测与防御方法》针对复杂系统软件中广泛出现的悬垂指针问题进行研究，提出了一种名为DangDone的垂悬指针防御方法，通过在编译时的程序转换来定位潜在的垂悬指针并防御use-after-free或double-free漏洞.
《自主机器人多智能体软件架构及伴随行为机制》提出了基于多智能体的自主机器人控制软件软件架构，以及基于相应架构的伴随行为机制.该工作基于分步规划和动态决策的思想设计并实现了相应自主决策算法DAAB，并在相应仿真环境和实际机器人环境上进行了案例分析.
《轨道交通联锁领域特定语言的形式化》基于轨道交通联锁系统中故障的随机性和行为实时性的特点，提出了基于建立随机混成系统模型来仿真、预测轨道交通连锁系统的方法.该方法在实际联锁系统进行实例研究，并在UPPAAL-SMC平台上进行了事故模型的预测分析.
《基于AADL的失效概率分配及安全性评估方法》综合考虑AADL架构的层次化设计、模型复杂度和构件失效造成影响的严重程度，针对安全关键系统提出基于AADL的失效概率分配方法，以应对安全性评估过程中如何分配失效概率的问题.相关技术在飞控CPS系统上进行了实例研究.
《马尔可夫信息物理系统拒绝服务攻击安全控制》研究了马尔可夫跳变信息物理系统在模态依赖拒绝服务（DoS）攻击下的安全控制问题.提出了一种新颖的模态依赖事件触发策略来减少网络资源消耗.
本专题面向信息物理系统的研究人员和工程人员，内容涵盖系统建模、系统架构、可信保障等领域，反映了我国学者在相关领域的高水平研究成果.感谢《软件学报》编委会、CCF软件工程专委会、系统软件专委会对专题工作的指导和帮助，感谢专题全体评审专家及时、耐心、细致的评审工作，感谢踊跃投稿的所有作者.希望本专题能够对形式化方法的科研工作有所促进.
专刊特约编辑、北航计算机学院刘超教授在专刊的筹划阶段分享了大量宝贵的经验，并在征稿、审稿等环节做了大量的工作，使得专刊实施过程得以顺利开展.然而，在本专刊即将完成之际，刘超老师却因病永远离开了我们.刘老师睿智、谦逊、渊博、平和，为推动我国软件工程事业发展做出了重要贡献，我们借此表达深深的怀念和敬意.
     

面向CPS系统仿真的建模方法研究与设计

CPS仿真建模在构建CPS系统时具有重要意义,不仅能够在系统开发过程中对系统进行验证和测试,而且是模型驱动开发中的重要环节。CPS系统通过精化和提炼可分为物理实体和计算实体,采用具有动态连续性、基于时间的运动状态行为模型构建物理实体;计算实体模型则采用基于有限状态机的离散系统行为模型进行构建。通过面向时间的状态精化对两种行为模型进行扩展,将两种扩展模型进行融合,完成CPS系统的建模仿真。分析了构建计算实体模型的统一建模语言(UML)以及构建物理实体模型的simulink/RTW建模工具的可行性,提出了基于UML框架的两种异质模型融合方法。     

面向CPS时空性质验证的混成AADL建模与模型转换方法

随着信息物理融合系统CPS(cyber physical system)研究的深入,CPS的安全性问题越来越受到人们的广泛关注,如何验证CPS时空不一致的安全性问题已经成为研究热点.针对该问题,提出了面向CPS时空性质验证的混成AADL(architecture analysis&design language)建模与...     

一种信息物理融合系统行为预测模型

信息物理融合系统(CPS)是一类集成了计算系统、通信网络、传感器网络、控制系统和物理系统的新型互联系统。由于CPS内部异构单元之间的通讯、协同和交互的形式错综复杂,目前尚无统一的模型进行描述和分析,因此对其行为的建模和预测是一个难点问题。首先以混杂系统、模糊集理论和人因学方法为基础,提出一种模糊时间混合Petri网,随后通过对一类典型CPS的行为进行建模和分析,实现了CPS动态行为和状态迁移的预测,最后以仿真数据验证了模型的有效性。该模型可用于分析CPS中的物理世界连续状态和信息世界离散事件之间的联系和交互,有助于研究CPS中的不确定性问题和系统组成单元之间的异步并发关系,为CPS的行为预测、状态评估和实时控制提供了有效方法。     

基于XML的信息物理融合系统组件建模与仿真

信息物理融合系统（CPS）涉及多种计算模型的集成和协同工作，针对CPS设计方法不统一、重塑性差、复杂度高、难以协同建模验证等问题，提出一种结构化、可描述行为的异元组件模型。首先，用统一组件建模方法进行建模，解决模型不开放问题；然后，用可扩展标记语言（XML）规范描述各类组件，解决不同计算模型描述语言不一致和不可扩展问题；最后，用多级开放组件模型的协同仿真验证方式进行仿真验证，解决验证的不可协同问题。通过通用组件建模方法、XML组件规范描述语言以及验证工具平台XModel对医用恒温箱进行了建模、描述和仿真。医用恒温箱的案例表明，这种模型驱动建立可重塑异元组件并确认其设计正确性的过程，支持信息物理协同设计和边构建边纠正，可避免在系统实现过程中发现问题时再进行反复修改。     

混成时空Petri网的CPS实时事件模型

在分析网络物理系统（ CPS）特点的基础上,提出了一种新的CPS体系结构,并对事件进行形式化定义。提出了一种新的CPS物理实体的形式化建模方法。在Petri网的基础上引入时空因素和连续变量,构造了混成时空Petri网（ HSPN）模型,使其不仅能够描述物理实体逻辑和时间层次的行为,而且能够描述物理实体位置变迁所引起的状态变化。将其应用于实时事件CPS模型设计,以医疗控制系统为例,分析建模方法的可行性。     

面向信息物理融合系统的多源异构数据交互模型

在信息物理融合系统（Cyber-physical system，CPS）中，传统多源异构数据集成模型难以通过中间件实现异构系统间的概念层关系映射，存在系统难以扩展和传输性能低等问题。基于上述问题和挑战，提出了一个面向CPS的异构数据交互模型。设计数据对象模型实现物理系统和仿真系统高层概念映射；定义监测类和控制类元数据，针对不同的数据类型使用增量或全量字段更新以降低网络负载；基于Protobuf协议设计系统的通信模型，提高系统的扩展能力。基于该数据交互模型和高层体系结构（High level architecture， HLA）/数据分发服务（Data distribution service， DDS）系统中间件实现了一个CPS原型系统，验证了模型的可用性并对比了报文的压缩性能。     

AADL+: a simulation-based methodology for cyber-physical systems

AADL (architecture analysis and design language) concentrates on the modeling and analysis of application system architectures. It is quite popular for its simple syntax, powerful functionality and extensibility and has been widely applied in embedded systems for its advantage. However, it is not enough for AADL to model cyber-physical systems (CPS) mainly because it cannot be used to model the continuous dynamic behaviors. This paper proposes an approach to construct a new sublanguage of AADL called AADL+, to facilitate the modeling of not only the discrete and continuous behavior of CPS, but also interaction between cyber components and physical components. The syntax and semantics of the sublanguage are provided to describe the behaviors of the systems. What’s more, we develop a plug-in to OSATE (open-source AADL tool environment) for the modeling of CPS. And the plug-in supports syntax checking and simulation of the system model through linking with modelica. Finally, the AADL+ annex is successfully applied to model a lunar rover control system.     

Composing domain-specific design environments

Domain-specific integrated development environments can help capture specifications in the form of domain models. These tools support the design process by automating analysis and simulating essential system behavior. In addition, they can automatically generate, configure, and integrate target application components. The high cost of developing domain-specific, integrated modeling, analysis, and application-generation environments prevents their penetration into narrower engineering fields that have limited user bases. Model-integrated computing (MIC), an approach to model-based engineering that helps compose domain-specific design environments rapidly and cost effectively, is particularly relevant for specialized computer-based systems domains-perhaps even single projects. The authors describe how MIC provides a way to compose such environments cost effectively and rapidly by using a metalevel architecture to specify the domain-specific modeling language and integrity constraints. They also discuss the toolset that implements MIC and describe a practical application in which using the technology in a tool environment for the process industry led to significant reductions in development and maintenance costs     

Workflow simulation for operational decision support using event graph through process mining

It is increasingly common to see computer-based simulation being used as a vehicle to model and analyze business processes in relation to process management and improvement. While there are a number of business process management (BPM) and business process simulation (BPS) methodologies, approaches and tools available, it is more desirable to have a systemic BPS approach for operational decision support, from constructing process models based on historical data to simulating processes for typical and common problems. In this paper, we have proposed a generic approach of BPS for operational decision support which includes business processes modeling and workflow simulation with the models generated. Processes are modeled with event graphs through process mining from workflow logs that have integrated comprehensive information about the control-flow, data and resource aspects of a business process. A case study of a credit card application is presented to illustrate the steps involved in constructing an event graph. The evaluation detail is also given in terms of precision, generalization and robustness. Based on the event graph model constructed, we simulate the process under different scenarios and analyze the simulation logs for three generic problems in the case study: 1) suitable resource allocation plan for different case arrival rates; 2) teamwork performance under different case arrival rates; and 3) evaluation and prediction for personal performances. Our experimental results show that the proposed approach is able to model business processes using event graphs and simulate the processes for common operational decision support which collectively play an important role in process management and improvement.     

An investigation of learners' collaborative knowledge construction performances and behavior patterns in an augmented reality simulation system

The purpose of this study was to investigate how a mobile collaborative augmented reality (AR) simulation system affects learners' knowledge construction behaviors and learning performances. In this study, 40 undergraduate students were recruited and divided into dyads to discuss a given task either with the assistance of a mobile collaborative AR system or traditional 2D simulation system. The participants' knowledge acquisition regarding elastic collision was evaluated through a pre-test and a post-test comparison. Learners' knowledge construction behaviors were qualitatively identified according to an adapted three-category coding scheme including construction of problem space (PS), construction of conceptual space (CS), and construction of relations between conceptual and problem space (CPS), and were then analyzed by adopting lag sequential analysis. The results indicated that the learners who learned with the AR system showed significant better learning achievements than those who learned with the traditional 2D simulation system. Furthermore, the sequential patterns of the learners' behaviors were identified, including three sustained loops (PS→PS, CS→CS, CPS→CPS), a bi-directional path between the PS and CPS activities (PS↔CPS), and a one way path from the PS activity to the CS activity (PS→CS). The revealed behavior patterns suggest that the AR Physics system may serve as a supportive tool and enable dyad learners to respond quickly to the displayed results and support their knowledge construction processes to produce a positive outcome. Based on the behavioral patterns found in this study, suggestions for future studies and further modifications to the system are proposed.     

Exploring how users engage with hybrid process artifacts based on declarative process models: a behavioral analysis based on eye-tracking and think-aloud

Process design artifacts have been increasingly used to guide the modeling of business processes. To support users in designing and understanding process models, different process artifacts have been combined in several ways leading to the emergence of the so-called “hybrid process artifacts”. While many hybrid artifacts have been proposed in the literature, little is known about how they can actually support users in practice. To address this gap, this work investigates the way users engage with hybrid process artifacts during comprehension tasks. In particular, we focus on a hybrid representation of DCR Graphs (DCR-HR) combining a process model, textual annotations and an interactive simulation. Following a qualitative approach, we conduct a multi-granular analysis exploiting process mining, eye-tracking techniques, and verbal data analysis to scrutinize the reading patterns and the strategies adopted by users when being confronted with DCR-HR. The findings of the coarse-grained analysis provide important insights about the behavior of domain experts and IT specialists and show how user’s background and task type change the use of hybrid process artifacts. As for the fine-grained analysis, user’s behavior was classified into goal-directed and exploratory and different strategies of using the interactive simulation were identified. In addition, a progressive switch from an exploratory behavior to a goal-directed behavior was observed. These insights pave the way for an improved development of hybrid process artifacts and delineate several directions for future work.

     

CPS系统物理实体时空一致性建模与分析

CPS作为一个混合系统,是计算系统和物理系统的集中体现,注重计算进程和物理进程行为一致性分析与刻画。传统建模方式只针对物理进程和计算进程进行单一建模,难以满足CPS物理实体状态转移时空一致性的要求,在此基础上提出一种新的建模方法。将CPS时空状态转移融合成一个状态转移实时时空事件,并在时间Petri网基础上引入空间标签,建立时空Petri网模型,利用时空Petri网对物理实体状态转移过程进行分析。最后通过列车控制系统实例进一步分析了时空模型的有效性,从而例证了该方法的可行性。     

基于AOP的时空Petri网的CPS建模

信息-物理融合系统(Cyber-Physical System,CPS)作为一系列物理过程和计算过程的紧密集成,体现为物理世界和信息世界的交互与融合。针对CPS的时空及非功能属性,提出一种面向方面的时空Petri网建模方法,在保证时空一致性的前提下,分离系统中的核心关注点和横切关注点,将横切关注点单独作为方面进行分析,并将构建规则方面重新织入系统。该方法在系统设计阶段可以对不同的非功能属性进行形式化分析,提高了系统的可靠性和可维护性。最后通过实例说明了该方法的可行性。     

An approach of implementing general learning companions for problem solving

Adding a learning companion, a computer simulated social agent, to a computer based learning system can enhance its educational value by enriching the way in which the computer and the user interact. This paper presents a novel simulation approach, named General Companion Modeling (referred to hereinafter as GCM), to implement learning companions in a general problem-solving domain. DwestAgent, a learning companion system, is also implemented using the GCM approach to demonstrate the feasibility of the proposed approach. In addition, the approach can help developers of learning companions clarify implementation issues and requirements involved in simulating: (1) domain competencies, (2) learning competencies, (3) behaviors as a peer tutor, and (4) behaviors as a peer tutee of a learning companion. Using GCM, one can simulate learning companions with various characteristics by adjusting parameters within the proposed simulation framework.     

Implementing a hybrid simulation model for a Kanban-based material handling system

Plant floor material handling is a loose loop in most assembly plants. Simulation offers a quick, controllable and tunable approach for prototyping complex material handling processes in manufacturing environments. This paper proposes a hybrid simulation approach, using both discrete event and agent-based technologies, to model complex material handling processes in an assembly line. A prototype system is implemented using a commercial multi-paradigm modeling tool. In this prototype, JIT principles are applied to both the production and the material handling processes. The system performance is evaluated and system optimization directions are suggested. The proposed hybrid modeling approach facilitates the implementation of a responsive and adaptive environment in that various “what-if” scenarios can be simulated under different simulation configurations and real-time situations.