Software implemented transient fault detection in space computer

Computer systems operating in space environment are subject to different radiation phenomena, whose effects are often called “Soft Error”. Generally, these systems employ hardware techniques to address soft-errors, however, software techniques can provide a lower-cost and more flexible alternative. This paper presents a novel, software-only, transient-fault-detection technique, which is based on a new control flow checking scheme combined with software redundancy. The distinctive advantage of our approach over other fault tolerance techniques is the lower performance overhead with the higher fault coverage. It is able to cope with transient faults affecting data and the program control flow. By applying the proposed technique on several benchmark applications, we evaluate the error detection capabilities by means of several fault injection campaigns. Experimental results show that the proposed approach can detect more than 98% of the injected bit-flip faults with a mean execution time increase of 153%.     

Research on a six-phase permanent magnet synchronous motor system at dual-redundant and fault tolerant modes in aviation application

With the development of more/all electrical aircraft technology,an electro-mechanical actuator (EMA) is more and more used in an aircraft actuation system.The motor system,as the crucial part of an EMA,usually adopts the redundancy technology or fault tolerance technology to improve the reliability.To compare the performances of these two motor systems,a 10-pole/ 12-slot six-phase permanent magnet synchronous motor (PMSM) is designed with the concentrated single-layer winding,which is able to operate at dual-redundant and fault tolerant modes.Furthermore,the position servo performances of the six-phase PMSM at dual-redundant and fault tolerant modes are analyzed,including the normal and fault conditions.In addition,a variable structure proportional-integral-derivative (PID) control strategy is proposed to solve the performance degradation problem caused by phase current saturation.Simulation and experimental results show that the fault tolerant PMSM has a better position servo performance than the dual-redundant PMSM,and the variable structure PID control strategy is able to improve the performance due to phase current saturation.     

基于低冗余度的传感器故障诊断研究

对于大型飞机来说,飞行控制系统各部件(包括传感器)多采用高余度的硬件配置来提高系统的任务可靠性,但对小型飞机来说,由于受重量、空间及费用等原因的影响,一些传感器不适合安装三余度或四余度传感器。对于二余度或单传感器来说,如何鉴别故障传感器或判断传感器是否发生故障较为困难。同样,传统的故障诊断与隔离方法并不能隔离三余度传感器系统中的多个故障。为了解决低冗余度传感器故障诊断问题,提出一种不依赖数学模型的奇偶方程方法与小波分析相结合的传感器故障诊断方法。     

一种新型高效容错体系结构的研究与实现

由于辐射而在电路的时序逻辑部分和组合逻辑部分产生的逻辑软错误已经逐渐成为阻碍系统可靠性和稳定性的主要威胁。提出了一种结合了基于主／g．1atch设计和改进的时间冗余策略两种技术的容错体系结构，通过ISCAS’89测试基准电路进行验证并对实验结果的分析发现，该容错体系结构获得了很高的容错性能。     

多相开路故障下的双三相PMSM统一容错控制策略

多相电机在定子开路故障下具有良好的容错性能,与此相关的设备和控制策略改进方面的研究理论也不断被提出。然而,却少有基于统一模型的适用于多相开路故障的容错控制策略。提出了一种应用于双三相永磁同步电机(PMSM)系统三相或三相以下开路故障的容错控制策略,并获得了良好的电机电力和动态性能。针对发生单相到三相开路故障的PMSM提出了统一数学模型,提取出每种故障下对应电机不对称性的矩阵。通过电压方程,推导出每种故障对应的解耦变换矩阵。为了对相电流中的每种谐波进行无差别抑制,建立了谐波子空间。考虑开路故障相数的增加,提出了用于三相开路的有中性点电流的容错控制策略,达到了降低相电流幅值和提升系统冗余度的目的。最后通过试验和仿真结果,验证了理论分析的正确性。     

Fault tolerant attitude control of under-actuated spacecraft: Theory and experiment

This paper investigates fault tolerant attitude control theory and experiment for under-actuated spacecraft with one reaction wheel completely broken and two others suffering actuator faults of partial loss of effectiveness or bias. A non-smooth robust adaptive fault tolerant control law is proposed under the zero-momentum and input saturation conditions. It shows that the available reaction wheels need to produce sufficient control torque for the fault tolerance. Such a new control method is implemented in a semi-physical simulation system of an air-bearing platform. Experimental results show the effectiveness of the proposed method in spacecraft practical engineering.     

Reconfiguration of flight control systems for actuator failures

We consider the problem of designing fault tolerant control for transient failures in the flight control system caused by harsh electromagnetic environments. We examine principles of fault tolerant design and discuss integrated local supervisory control of these systems. As an example, we present a sample design of a control mixer to achieve fault tolerance in the event of failures in the actuators     

Fault diagnostics and fault tolerant control

A novel simultaneous fault detection and diagnostics (FDD) and fault tolerant control (FTC) strategy for nonlinear stochastic systems in closed loops based on a continuous stirred tank reactor (CSTR) is presented. The purpose of control is to track the reactant concentration setpoint. Instead of output feedback we propose here to use proportional-integral-derivative (PID) state feedback, which is shown essential to achieve FTC against sensor faults. A new concept of “equivalent bias” is proposed to model the sensor faults. Both the states and the equivalent bias are on-line estimated by a pseudo separate-bias estimation algorithm. The estimated equivalent bias is then evaluated via a modified Bayes' classification based algorithm to detect and diagnose the sensor faults. Many kinds of sensor faults are tested by Monte Carlo simulations, which demonstrate that the proposed strategy has definite fault tolerant ability against sensor faults, moreover the sensor faults can be on-line detected, isolated, and estimated simultaneously     

多电飞机容错作动系统拓扑结构分析

针对多电飞机电力作动系统,提出永磁容错电机及其容错驱动控制的拓扑结构,探讨系统的电气故障模式,研究防止故障传播的电、磁、热隔离设计,在理论上给出了容错电机相数的选取方法,采用独立的同轴电机组件实现高冗余系统。研究结果表明:电机、功率变换器和供电通道均采用以相为基本单位的模块化拓扑结构可实现多电飞机对作动系统的高容错要求。     

基于解耦矢量控制的五相永磁同步电机容错控制策略

针对五相永磁同步电机两相开路故障的运行工况,提出了一种基于解耦矢量控制理论的故障容错控制策略.该策略通过在两相开路故障下的同步旋转坐标系内建立电机的数学模型,构造解耦变换矩阵,将电流控制中id和iq轴解耦,达到两相开路故障下容错运行的目的 .仿真结果表明,在五相永磁同步电机两相开路故障下,基于解耦矢量控制理论的故障容错控制策略能够实现电机驱动系统的高品质运行,具有控制简单、转矩波动小、容错能力强等优点.     

电力作动器用高可靠性永磁容错电机控制系统的设计及其试验分析

 针对电力作动器的高可靠性要求,结合转子磁钢采用离心结构的六相十极永磁容错电机(FTPMM),提出一种基于电流直接控制法的容错控制系统。当电机绕组或功率管发生断路及短路故障时,系统无需硬件故障辨识信号及软件算法切换就可实现系统的强容错功能,即故障后电机输出转速不变,输出功率与发生故障的相数有关,当电机系统出现一相、两相、三相故障时,电机分别可输出100%、80%、60%的额定功率;设计了一台750 W六相十极永磁容错电机的原理样机及其全数字化控制器,证明了该容错控制策略的正确性及整个电机控制系统的强容错性及可行性。     

电力作动器用高可靠性永磁容错电机控制系统的设计及其试验分析

针对电力作动器的高可靠性要求,结合转子磁钢采用离心结构的六相十极永磁容错电机(FTPMM),提出一种基于电流直接控制法的容错控制系统。当电机绕组或功率管发生断路及短路故障时,系统无需硬件故障辨识信号及软件算法切换就可实现系统的强容错功能,即故障后电机输出转速不变,输出功率与发生故障的相数有关,当电机系统出现一相、两相、三相故障时,电机分别可输出100%、80%、60%的额定功率;设计了一台750 W六相十极永磁容错电机的原理样机及其全数字化控制器,证明了该容错控制策略的正确性及整个电机控制系统的强容错性及可行性。     

临近空间艇载计算机余度管理策略研究

平流层飞艇是可靠性要求很高的系统,需要由具有容错能力的艇载计算机来进行控制和管理。针对艇载计算机采用的余度结构进行了软件管理策略的研究和设计,提出了基于异构总线的握手机制节点故障检测方法、基于“看门狗”与“心跳”相结合的 CPU 故障检测方法、基于节点健康矩阵的互援式总线重构方法及基于有限状态机的多 CPU 并行处理系统自适应重构方法。故障注入试验表明,艇载计算机在遇到故障时能实时检测出故障,诊断故障类型,并对故障进行处理,实现系统重构,保证了平流层飞艇长期驻空时的安全飞行。     

FC环形通信网络双余度容错的设计与实现

随着航电系统的发展,传统的通信网络传输速率已经不能满足发展需要,因此,FC协议作为新一代的高性能网络通信协议被引入到航电系统中.如何基于FC协议设计出满足航电系统应用需求的通信网络成为FC技术研究的关键.本文介绍了一种面向航电系统应用的基于FC通信协议的双余度环网的设计与实现方案,着重从软硬件两个方面对系统的容错设计给出了说明,最后对系统的容错能力进行了全面的验证.     

Fault tolerant control with torque limitation based on fault mode for ten-phase permanent magnet synchronous motor

This paper proposes a novel fault tolerant control with torque limitation based on the fault mode for the ten-phase permanent magnet synchronous motor(PMSM) under various open-circuit and short-circuit fault conditions, which includes the optimal torque control and the torque limitation control based on the fault mode. The optimal torque control is adopted to guarantee the ripple-free electromagnetic torque operation for the ten-phase motor system under the post-fault condition. Furthermore, we systematically analyze the load capacity of the ten-phase motor system under different fault modes. And a torque limitation control approach based on the fault mode is proposed, which was not available earlier. This approach is able to ensure the safety operation of the faulted motor system in long operating time without causing the overheat fault. The simulation result confirms that the proposed fault tolerant control for the ten-phase motor system is able to guarantee the ripple-free electromagnetic torque and the safety operation in long operating time under the normal and fault conditions.     

航空发动机控制律容错重组设计

针对发动机数字电子控制系统中传感器易于出现故障的特点,以某型发动机为例,采用基于控制律容错重组方法在飞行包线内的不同点上设计出了发动机容错控制器。仿真结果表明：该控制器具有很好的容错能力,故障情况下系统的动态品质与正常情况下系统的动态品质具有良好的一致性。     

基于奇偶方程的FADS传感器故障检测方法

重复使用运载器（RLV）的嵌入式大气数据传感系统（FADS）中传感器的高可靠性是RLV飞行控制系统高可靠性的保障。结合FADS采用多个测压点冗余配置的特点,利用各传感器测量值之间存在的解析冗余关系,设计奇偶方程,实现对各个测压点故障传感器的有效检测。     

自适应滑模容错跟踪飞行控制律的设计

当飞行控制系统操纵面发生卡死或控制效率损伤故障时,采用自适应滑模控制方法进行容错跟踪飞行控制律的设计。采用单位向量法进行滑模控制器的设计,利用李雅普诺夫理论和Barbalat引理设计自适应滑模调节规律,同时能够保证闭环系统的渐近稳定性。利用某型飞机线性化模型进行仿真,结果表明,带有自适应调节规律的滑模控制方法不仅适合于正常情况下飞行控制律的设计,而且对操纵面损伤和卡死故障情况具有较强的适应能力,具有很好的跟踪控制效果和强鲁棒性。     

基于冷备份多模冗余结构的BRAM自修复方法

随着现场可编程门阵列（FPGA）在空天电子系统中的广泛应用,受空间辐射恶劣环境影响,FPGA中重要的存储器电路BRAM,因采用SRAM技术极易发生位翻转故障,虽绝大部分情况表现为瞬时故障,但永久故障依然存在。针对BRAM自修复方法仅修复瞬时故障的现状,对能同时修复瞬时故障和永久故障的自修复方法进行研究,提出了一种冷备份多模冗余结构,用3个热备份模块和1个冷备份模块来构造BRAM,该结构可通过三模冗余刷新方法修复瞬时故障和冷备份替换方法修复永久故障。给出了整个BRAM自修复系统中各模块的电路结构和实现方法,实验验证了系统的自修复能力,并在可靠性、硬件资源和时间消耗3个方面,通过对比分析论证了自修复方法的有效性。     

航空发动机分布式控制系统动态输出反馈鲁棒H∞容错控制

针对存在网络诱导时延、外部干扰的航空发动机分布式控制系统,提出了执行机构发生部分失效故障时的输出反馈容错控制方法。对航空发动机分布式控制系统中网络诱导时延以及执行器部分失效问题进行量化说明,在此基础上,采用动态输出反馈控制器建立增广闭环系统。针对所建立的增广闭环系统,对H∞性能约束下的增广闭环系统稳定性进行分析,并利用线性矩阵不等式理论设计了输出反馈H∞容错控制器。仿真结果表明,当两个执行机构输出值分别为衰减80%和50%时,控制系统在所设计的控制器作用下均方渐进稳定,且具有H∞性能指标为0.63,同样在正向偏差故障条件下也具有很好的容错能力。