航空火控计算机的容错技术分析

可靠性是航空火控系统主要指标,而容错技术是提高航空火控系统可靠性的重要途径。本文根据可靠性原理和容错技术,分析了容错技术在火控系统中的应用,并用实际火控系统：飞机军械检测系统、平显自检系统,分别分析了故障检测技术、屏蔽技术和动态冗余技术,最后对火控计算机实现容错式硬件和容错软件进行了分析和研究。     

具有数据包丢失的网络控制系统的容错控制

针对一类多输入多输出网络控制系统,将数据包丢失视为系统发生执行器或传感器故障,并用最近一次的采样数据代替本周期未能成功传输的数据,对系统进行容错控制器的设计。首先以控制量丢失为例,基于Lyapunov稳定性理论,推导出了使系统稳定的条件,然后推广到检测量丢失的情况。最后通过仿真示例验证了文中方法的有效性,并对仿真结果进行了分析。     

Fault-tolerant control for uncertain linear systems via adaptive and LMI approaches

This paper proposes a fault-tolerant control scheme for linear systems with mismatched uncertainties which are assumed to be norm-bounded, affine and polytopic, respectively. The linear fractional transformation (LFT) and linear matrix inequality (LMI) techniques are introduced to handle the mismatched uncertainties, and the adaptive techniques are used to compensate actuator faults. By using the cone complementary linearisation algorithm, the resulting stability criteria are converted into solvable ones. Then, on the basis of Lyapunov stability theory, it is shown that the solutions to the closed-loop system and error system are uniformly bounded, especially, the states converge asymptotically to zero. Finally, simulations are given to illustrate the effectiveness and advantages of the proposed theoretical results.     

Fault-tolerant cooperative tasking for multi-agent systems

A natural way for cooperative tasking in multi-agent systems is through a top-down design by decomposing a global task into subtasks for each individual agent such that the accomplishments of these subtasks will guarantee the achievement of the global task. In our previous works [Karimadini, M., and Lin, H. (2011c), ‘Guaranteed Global Performance Through Local Coordinations’, Automatica, 47, 890--898; Karimadini, M., and Lin, H. (2011a), ‘Cooperative Tasking for Deterministic Specification Automata’, submitted for publication, online available at: http://arxiv.org/abs/1101.2002], we presented necessary and sufficient conditions on the decomposability of a global task automaton between cooperative agents. As a follow-up work, this article deals with the robustness issues of the proposed top-down design approach with respect to event failures in the multi-agent systems. The main concern under event failure is whether a previously decomposable task can still be achieved collectively by the agents, and if not, we would like to investigate that under what conditions the global task could be robustly accomplished. This is actually the fault-tolerance issue of the top-down design, and the results provide designers with hints on which events are fragile with respect to failures, and whether redundancies are needed. The main objective of this article is to identify necessary and sufficient conditions on failed events under which a decomposable global task can still be achieved successfully. For such a purpose, a notion called passivity is introduced to characterise the type of event failures. The passivity is found to reflect the redundancy of communication links over shared events, based on which necessary and sufficient conditions for the reliability of cooperative tasking under event failures are derived, followed by illustrative examples and remarks for the derived conditions.     

计算机系统容错技术研究

针对计算机系统中软、硬件可靠性问题的不同特点,讨论容错技术的最新发展现状,分析计算机系统中的各种容错方法,包括传统的冗余设计、错误回卷恢复机制以及当前研究较多的一般化容错设计方法等,研究目前已有的一些容错方法在反应延迟、容错成本、精确量化、异构同步、可靠性建模等方面存在的缺陷以及待解决关键问题,并对如何进一步更好地完善和使用这些容错方法进行总结。     

基于输出反馈的不确定NCS鲁棒容错控制

研究了一类具有网络诱导时延和参数不确定性网络化控制系统鲁棒容错控制问题.基于将时延的不确定性转换为系统状态方程系数矩阵不确定性的NCS模型,同时考虑系统参数不确定性对系统的影响,应用Lyapunov稳定性理论和LMI方法,采用输出反馈控制策略,推证出了保证闭环网络化控制系统在执行器或传感器发生故障时仍渐进稳定的充分条件,并以求解线性矩阵不等式组给出了容错控制器的设计方法,最后用仿真算例验证了此方法的可行性和有效性.     

一种具有自主学习能力的并发协商模型

提出一种具有自主学习能力的并发协商模型,通过使用增强学习方法的Q学习算法生成协商提议,使用相似度方法评价提议,使得Agent能够在半竞争、信息不完全和不确定以及存在最大协商时间的情况下,更为有效地完成多议题多Agent并发协商。     

Fault-tolerant control of delta operator systems with actuator saturation and effectiveness loss

This paper studies the problem of robust fault-tolerant control against the actuator effectiveness loss for delta operator systems with actuator saturation. Ellipsoids are used to estimate the domain of attraction for the delta operator systems with actuator saturation and effectiveness loss. Some invariance set conditions used for enlarging the domain of attraction are expressed by linear matrix inequalities. Discussions on system performance optimisation are presented in this paper, including reduction on computational complexity, expansion of the domain of attraction and disturbance rejection. Two numerical examples are given to illustrate the effectiveness of the developed techniques.     

N为偶数的并发差错可定位N-模冗余结构

N－模冗余结构是一种广泛应用的容错结构，其有效性是建立在它所包含的故障模型块数不超过[（N－1）／2]的假设之上的，而破坏该假设的可能途径有故障累积和同时故障，防止故障模块累积的方法之一是使冗余系统具有故障定位能力，然后及时地将故障模块予隔离和替换。传统的静态和动态硬件冗余结构或都不具有故障定位能力，中者不提供显式的故障定位信息，并且对附电路本身的故障是无法处理的，为此，针对静态硬件冗余结构，作者等人曾提出了N为奇数情况下的差错定位解决方案，而该文则提出了N为偶数情况下的相应解决方案。     

具有Neumann边界的分布参数切换系统的容错控制

本文研究了一类具有Neumann边界条件的分布参数切换系统的容错控制问题.当执行器失效或部分失效时,运用Lyapunov函数法和Green公式,获得了闭环切换系统混杂状态反馈容错控制器存在的充分条件.然后运用线性矩阵不等式将容错控制器设计问题转化为一组线性矩阵不等式求可行解的问题,因而可以借助MATLAB中线性矩阵不等式工具箱来完成.同时,运用Poincare不等式减少控制系统设计的保守性.最后通过数值算例,验证所提出设计方法的有效性.     

带有输出约束条件的随机多智能体系统容错控制

在有向通讯拓扑图下,针对一类具有输出约束和执行器偏差增益故障的非严格反馈随机多智能体系统,提出一种自适应神经网络容错控制设计方案.采用神经网络逼近未知非线性函数,构造障碍李雅普诺夫函数处理系统的输出约束问题,以反步法和动态面技术为框架,结合Nussbaum函数设计自适应神经网络容错控制方法.基于李雅普诺夫稳定性理论,证明所有跟随者输出与领导者输出达到一致,闭环系统的所有信号依概率半全局一致最终有界且系统输出限制在给定紧集内.论文最后通过仿真实验验证所给出控制方案的有效性.     

Fault-tolerant cooperative output regulation for multi-vehicle systems with sensor faults

This paper presents a unified framework of fault diagnosis and fault-tolerant cooperative output regulation (FTCOR) for a linear discrete-time multi-vehicle system with sensor faults. The FTCOR control law is designed through three steps. A cooperative output regulation (COR) controller is designed based on the internal mode principle when there are no sensor faults. A sufficient condition on the existence of the COR controller is given based on the discrete-time algebraic Riccati equation (DARE). Then, a decentralised fault diagnosis scheme is designed to cope with sensor faults occurring in followers. A residual generator is developed to detect sensor faults of each follower, and a bank of fault-matching estimators are proposed to isolate and estimate sensor faults of each follower. Unlike the current distributed fault diagnosis for multi-vehicle systems, the presented decentralised fault diagnosis scheme in each vehicle reduces the communication and computation load by only using the information of the vehicle. By combing the sensor fault estimation and the COR control law, an FTCOR controller is proposed. Finally, the simulation results demonstrate the effectiveness of the FTCOR controller.     

基于CAN总线的VDR系统容错主控制器的设计与实现

采用CAN总线技术的船载航行数据记录仪VDR(voyage data recorder)设计方案满足了系统需求,同时主控制器采用动态冗余设计提高了系统的可靠性。该方案可以满足VDR系统对稳定性的要求,并在实践中得到初步验证。     

短时延多包传输网络控制系统的容错控制

研究了存在数据丢失的短时延多包传输网络控制系统在静态调度和动态调度下的控制器设计问题。把未能成功传输数据的传感器节点视为暂时失效,将网络控制系统建模为一类具有时变传感器“故障”的系统。在静态调度策略下,将系统建模为一类具有一定切换规则的周期系统,利用容错控制理论和周期系统理论得到系统稳定性判据;在动态调度策略下,将系统建模为一类具有有限子系统的自主切换系统,利用容错控制理论和切换系统理论给出了系统的稳定性条件。并利用控制器和观测器的协同设计方法给出了系统在静态调度和动态调度下的容错控制律和状态观测器设计方法。数值仿真算例证明了结论的可行性和有效性。     

基于观测器的非线性网络控制系统容错控制

研究了一类基于观测器的非线性连续网络控制系统容错控制器设计问题.针对传感器采用时间驱动方式,控制器和执行器均采用事件驱动方式的网络控制系统,设计了观测器,建立了基于状态观测器的增广闭环系统模型.利用线性矩阵不等式和自由权矩阵的方法,推导出闭环系统渐近稳定的充分条件,给出了观测器和容错控制器协同设计的方法.实例仿真证明了所用方法的有效性.     

Fault-tolerant control for a class of non-linear systems with dead-zone

In this paper, a fault-tolerant control scheme is proposed for a class of single-input and single-output non-linear systems with the unknown time-varying system fault and the dead-zone. The non-linear state observer is designed for the non-linear system using differential mean value theorem, and the non-linear fault estimator that estimates the unknown time-varying system fault is developed. On the basis of the designed fault estimator, the observer-based fault-tolerant tracking control is then developed using the backstepping technique for non-linear systems with the dead-zone. The stability of the whole closed-loop system is rigorously proved via Lyapunov analysis and the satisfactory tracking control performance is guaranteed in the presence of the unknown time-varying system fault and the dead-zone. Numerical simulation results are presented to illustrate the effectiveness of the proposed backstepping fault-tolerant control scheme for non-linear systems.     

一种片上网络的低延迟容错算法

为解决片上网络容错问题,利用端到端模式设计一种低延迟可靠传输算法。该算法利用发送端主动发送冗余数据包获得较小的延迟,将数据分成包集以提高链路利用率,进一步降低延迟。发送端只在收到接收端对当前包集的确认后才发送下一个包集的数据,由此保证高可靠性。通过不断发送数据包及端到端的反馈保证传输的正确性。NS-2仿真实验结果证明,该算法延迟低,片上通信可靠性高,可以有效处理传输过程中的瞬时错误。     

交替互补定位器及其用于双模比较冗余结构的差错定位

双模比较冗余结构是一种广泛应用的低成本容错结构。当两个冗余模块之一发生故障时,比较器将给出差错检测指示输出,该输出既可以按中断信号形式通知系统作出相应的差错处理,也可以按硬件信号形式直接用于终止系统工作或启动重构,目的是防止故障冗余结构给出错误输出,或者确保系统能够提供连续的服务。这种冗余结构的缺点是比较器不能确切指明故障模块,并因此而需要较大的时间开销来完成系统重构和恢复操作。为解决这一问题,提出了一种具有并发输出差错定位功能的双重比较冗余结构。其中单个冗余模块的输出是一个交替矢量,两个冗余模块的输出形成了一个交替互补矢量,该矢量送入一个交替互补定位器。在正常输入情况下,根据定位器的输出就可以确定冗余系统是无差错的、还是冗余模块或定位顺本身存在故障。交替互补定位器由D型触发器和通用门电路构成,它被证明为是一个完全故障定位的定位器。由于所提出的双模比较冗余结构是基于时间冗余原理工作的,因此它适用于对速度要求并不是非常苛刻的容错系统。     

具有时变时延的网络化LPV系统的容错控制

针对一类具有时变时延以及Lipschitz非线性项的网络化线性参数变化系统,研究了系统中存在外部扰动、执行器和传感器同时发生随机故障时的容错控制问题。用Bernoulli分布序列描述执行器和传感器发生的随机故障,利用自由权矩阵方法处理时变时延。根据Lyapunov-Krasovskii稳定性定理和线性矩阵不等式（LMI）方法求出◢H◣▼∞▽容错控制器存在的充分条件,然后通过利用近似基函数和网格化技术将无限维的LMI求解问题转换为有限维的LMI问题,得到了相应的容错控制器增益。最后,通过数值仿真验证了所设计方法的有效性。