基于μCOS-II的实时多任务应用研究

在对多任务实时操作系统及μC/OS -II进行简要介绍的基础上,按照新型临床诊断用12导心电图机的系统设计中对控制软件和控制任务的实时要求,以μC/OS -II在心电信号采集系统中的应用为例,来对实时多任务系统的设计进行研究和探讨,讨论在实时多任务环境中,中断任务的设计方法,在资源共用条件下,解决资源竞争的任务的"原子性"问题.     

基于μC／OS-Ⅱ的实时多任务应用研究

在对多任务实时操作系统及μC／OS-Ⅱ进行简要介绍的基础上,按照新型临床诊断用12导心电图机的系统设计中对控制软件和控制任务的实时要求,以μC／OS-Ⅱ在心电信号采集系统中的应用为例,来对实时多任务系统的设计进行研究和探讨,讨论在实时多任务环境中,中断任务的设计方法,在资源共用条件下,解决资源竞争的任务的“原子性”问题。     

操作系统多任务应用模式实验开发

多个任务的并发执行是计算机操作系统的一个主要特征．为了满足Windows下分时多任务,或实时多任务应用系统的开发,给出通过C程序设计对操作系统中多任务并发执行设计模式开发,提出Windows下利用时钟中断方式进行多任务并发执行的方法。该模式实现系统内多任务在宏观上的“同时”运行,解决Windows环境下用户应用开发自己的分时,或实时多任务应用系统的一般方法和结构。     

操作系统多任务应用模式实验开发

多个任务的并发执行是计算机操作系统的一个主要特征,为了满足Windows下分时多任务,或实时多任务应用系统的开发,给出通过C程序设计对操作系统中多任务并发执行设计模式开发,提出Windows下利用时钟中断方式进行多任务并发执行的方法。该模式实现系统内多任务在宏观上的"同时"运行,解决Windows环境下用户应用开发自己的分时,或实时多任务应用系统的一般方法和结构。     

一个分布式环境下多任务模型软件的研制

为了更好地掌握VAXELN实时操作系统的使用和性能,验证VAXELN对实时控制系统开发的适应性,为研究DECnet上非透明的任务级通讯,我们建立了一个在VAXELN上运行的多任务系统,用该系统来对VAXELN的功能做一个测试和分析,并在分布式的硬件环境下利用VAXELN/DECnet——DOS/DECnet间非透明的任务级通讯实现了多任务模型的远程激活技术。本文重点阐述分布式环境多任务模型的实现方法。     

实时多任务系统可调度性工程评估方法研究

在实时多任务系统中,偶发任务的不可预见性会对实时系统的可调度性造成影响,甚至导致实时系统崩溃;针对此问题研究了对实时多任务系统进行工程评估的方法,将偶发任务对实时系统的影响进行了充分考虑和分析,建立了任务调度的目标规划模型,定义了超时百分比;仿真结果和物理实验都表明,最坏情况(图1中第三种情况)下,如果实时系统的超时百分比小于35%,系统任务就可以在任务时限内完成,这说明该评估方法能够保证实时系统可调度.     

基于时序的单片机多任务系统驱动策略

在单片机系统开发中，多任务系统容易出现调度阻塞。本文分析了产生任务阻塞的原因，提出了一种基于时序逻辑的多任务驱动策略，通过具体案例设计了常用外围模块的多任务驱动模板。实验结果表明，该多任务系统调度策略能够有效保证多任务系统运行流畅，有效解决了多任务阻塞问题，为基于单片机执行多任务系统开发提供了一个新思路。     

实时多任务系统的TPCQ建模方法

本文提出了一个基于定时的Ｐｅｔｒｉ网和立方体队列网络的实时多任务系统的建模方法－ＴＰＣＱ，它特别适合于描述含有同步、通信和立方体队列调度的复杂的实时多任务系统，也可以描述一般的实时多任务系统。文中讨论了ＴＰＣＱ模型，并且给出了一个建立实时多任务系统的ＴＰＣＱ模型的例子。     

μC/OS-Ⅱ在井下自动垂直钻井系统中的应用

石油行业井下自动垂直钻井系统嵌入式控制软件中既有少数实时性要求高的任务,也有多个非实时慢速任务,为解决软件中多任务并存、调度复杂的设计难点,以TMS320 F2812为硬件平台提出了一种将μC/OS-Ⅱ系统应用于自动垂直钻井系统控制软件的设计方案,软件采用了面向对象的设计方法,设计中在对执行的任务及优先级综合分析的基础上建立了多个TASK,并对消息队列和信号量的应用进行了重点说明,试验结果表明,软件运行正常、可靠,软件中的多个任务有序协调运行,快速任务能够确保其实时性,慢速任务也能按照预期规划执行,整个系统功能、性能达到了预期目标.     

实时多任务带宽转让的过渡过程研究

当一个实时系统的运行模式发生改变时,常需要进行带宽转让,并造成截止期丢失。为此,基于最早截止期优先调度的实时任务集,研究因出现新任务插入、现行任务加速而引起的带宽转让问题,依据老模式、过渡过程和新模式这3个阶段,提出一种多任务带宽转让模型,通过压缩某些现有任务来释放带宽,并证明即使系统在满负荷运行的情况下,只要新模式下所有任务的使用率(带宽)之和不大于1,截止期丢失的现象不可能出现在过渡过程后,并据此定义过渡过程的起点和终点。仿真结果表明,该模型能较为全面地展示多任务的带宽转让过程。     

一种面向CPS的控制应用程序协同验证方法

信息-物理融合系统是一种新型嵌入式系统计算模式,它集成了控制计算过程和受控对象,二者相互影响并有机结合.随着信息技术在现实世界中更加广泛、深入的应用,智能化程度不断提升,在具有信息物理紧密耦合特点的嵌入式系统中,嵌入式控制软件的功能比重急剧上升,作用更加突出.作为安全攸关的系统,需要引入形式化验证方法来保证嵌入式控制应用软件的安全性.本文基于自动机理论建立统一的系统验证模型,并针对系统的可达性、安全性（safety）和活性（liveness）等属性要求,提出了对该模型进行形式化验证的算法：基于有界模型检验方法,基于可达性将对系统模型的相关属性验证问题转换为可满足性判定问题.将活性转换为Büchi自动机,并基于四值语义进行判断.在求解过程中,通过偏序规约等手段化简了问题求解的规模,提高可验证系统的规模.另外结合协同仿真技术,灵活配置验证的场景,提高验证的可用性.实验结果表明,结合仿真,形式化协同验证方法可以有效地对系统进行验证.     

Review on Cyber-physical Systems

Cyber-physical systems (CPS) are complex systems with organic integration and in-depth collaboration of computation, communications and control (3C) technology. Subject to the theory and technology of existing network systems and physical systems, the development of CPS is facing enormous challenges. This paper first introduces the concept and characteristics of CPS and analyzes the present situation of CPS researches. Then the development of CPS is discussed from perspectives of system model, information processing technology and software design. At last it analyzes the main obstacles and key researches in developing CPS.      

Water Supply Networks as Cyber-physical Systems and Controllability Analysis

Cyber-physical systems (CPS) is a system of systems which consists of many subsystems that can stand alone in an individual manner and can be taken as a typical complex network. CPS can be applied in the critical infrastructures such as water supply networks, energy supply systems, and so on. In this paper, we analyze the structure of modern city water supply networks from the view of CPS theory. we use complex network theory to build an undirected and unweighted complex network model for the water supply networks to investigate the structural properties, and present the structure of the water supply networks and detect communities by a spectral analysis of the Laplacian matrix. Then, we analyze the structure and controllability of water supply networks by the structural controllability method. The results show the feasibility and effectiveness of the proposed complex network model.      

A co-simulation framework for design of time-triggered automotive cyber physical systems

Designing cyber-physical systems (CPS) is challenging due to the tight interactions between software, network/platform, and physical components. Automotive control system is a typical CPS example and often designed based on a time-triggered paradigm. In this paper, a co-simulation framework that considers interacting CPS components for assisting time-triggered automotive CPS design is proposed. Virtual prototyping of automotive vehicles is the core of this framework, which uses SystemC to model the cyber components and integrates CarSim to model the vehicle dynamics. A network/platform model in SystemC forms the backbone of the virtual prototyping. The network/platform model consists of processing elements abstracted by real-time operating systems, communication systems, sensors, and actuators. The framework is also integrated with a model-based design tool to enable rapid prototyping. The framework is validated by comparing simulation results with the results from a hardware-in-the-loop automotive simulator. The framework is also used for design space exploration (DSE).     

Automatic control systems for gas-turbine units in mini power stations: Testing automation at the stages of design and tuning

This paper presents the testing automation procedure for automatic control systems of gas-turbine units used as drives in small-size power stations. We substantiate the applicability of mathematical modeling techniques for power systems in testing automation problems of the control systems. Finally, multitasking mathematical models are derived, and a simulation software complex is developed for testing automation of the control systems; this is done by employing the mathematical model of a power system with an arbitrary configuration and structural elements.     

信息物理融合系统的时间需求一致性分析

信息物理融合系统(cyber-physical system,简称CPS)蕴藏着巨大的潜在应用价值.时间在CPS中起到非常重要的作用,应该在需求早期阶段明确.提出了一个基于逻辑时钟的CPS时间需求一致性分析框架.首先,构建了CPS软件的时间需求概念模型,提供时间需求和功能需求的基本概念,并给出了概念模型的形式化语义;然后,在模型制导下,从CPS的交互环境特性和约束中提取出其软件时间需求规约.基于形式化语义,定义了时间需求规约的一致性特性.为了支持形式化验证,将时间需求规约转换成NuSMV模型,用CTL公式表述要检测的特性,并使用NuSMV工具实施了一致性检测.     

实时系统构件非功能性接口语义规约

该文给出了基于构件的实时多任务应用系统图形化设计软件的具有分布式C/S关系实时构件的接口定义,主要论述实时构件非功能性接口模型,针对实时特性,提出构件的非功能性接口在时间性、调度性、合成性、同步、互斥以及资源设备控制方面的语义规约。     

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.     

Component-based analysis of embedded control applications

The widespread use of embedded systems requires the creation of industrial software technology that will make it possible to engineer systems being correct by construction. That can be achieved through the use of validated (trusted) components, verification of design models, and automatic configuration of applications from validated design models and trusted components. This design philosophy has been instrumental for developing COMDES—a component-based framework for distributed embedded control systems. A COMDES application is conceived as a network of embedded actors that are configured from instances of reusable, executable components—function blocks (FBs). System actors operate in accordance with a timed multitasking model of computation, whereby I/O signals are exchanged with the controlled plant at precisely specified time instants, resulting in the elimination of I/O jitter. The paper presents an analysis technique that can be used to validate COMDES design models in SIMULINK. It is based on a transformation of the COMDES design model into a SIMULINK analysis model, which preserves the functional and timing behaviour of the application. This technique has been employed to develop a feasible (light-weight) analysis method based on runtime observers. The latter are conceived as special-purpose actors running in parallel with the application actors, while checking system properties specified in Linear Temporal Logic. Observers are configured from reusable FBs that can be exported to SIMULINK in the same way as application components, making it possible to analyze system properties via simulation. The discussion is illustrated with an industrial case study—a Medical Ventilator Control System, which has been used to validate the developed design and analysis methods.     

实时多任务执行模型到VxWorks的代码映射

基于对实时多任务软件的抽象执行体的研究分析以及对VxWorks平台的分析,提出了实时多任务执行模型到VxWorks平台下C语言程序框架的系统调用的映射规则及代码。给出了实时对象之间的通信原理及映射方法。给出了实时时间管理的映射代码。