基于中间观测器的异构多智能体系统分布式故障估计

针对由无人机和无人车组成的异构多智能体系统,提出一种新型的基于中间观测器的分布式故障估计方法,可以实现对节点及其邻居执行器故障和系统状态的同时估计.首先,考虑到无人机在XOY平面与在OZ轴方向的运动相对独立,异构多智能体系统可以划分为由无人机和无人车组成的位置子系统的XOY平面以及无人机位置子系统的OZ轴;然后,设计基于中间变量的分布式故障估计观测器,不仅能同时估计出选定的智能体自身与其邻居的执行器故障和状态,也能克服观测器匹配条件的限制,并基于$H_\infty$性能指标求解观测器增益;最后,通过仿真实验验证所提出方法的可行性与有效性.     

基于有限时间未知输入观测器的一类受扰非线性系统故障检测与估计

针对一类非线性系统同时存在执行器故障、传感器故障和扰动的问题,提出一种基于有限时间未知输入观测器的故障检测与估计方法.首先,通过线性非奇异变换将原系统解耦为两个降阶的子系统,其中一个子系统只包含扰动,另一个子系统同时包含扰动和故障;然后,通过一阶低通滤波器获得新的状态并与子系统构成增广系统,实现将原系统的传感器故障转化为增广系统的执行器故障;接着,设计未知输入观测器对增广系统故障进行检测,实现在有限时间内估计出系统的扰动和故障,并通过理论分析验证所设计观测器的有限时间收敛性;最后,基于永磁同步电机(PMSM)转速系统进行仿真研究,仿真结果验证了所提出方法的有效性.     

基于向量集逆区间滤波的故障观测器设计

针对未知但有界扰动和噪声的线性时不变系统,提出一种基于向量集逆区间滤波的执行器故障观测器设计方法,以实现噪声未知但有界环境下的故障区间估计.通过将执行器故障视为增广状态向量,构造与原系统等价的增广系统;基于增广系统设计故障观测器,得到系统执行器故障的区间估计,同时利用多时刻的测量输出进行区间滤波;采用观测器估计区间和集逆收缩区间的交集,得到更紧致的当前时刻的状态区间,降低区间计算的包裹效应.仿真实例验证了所提方法的有效性和实用性.     

带有随机测量数据丢失及切换拓扑的传感器网络分布式$l_2-l_infty$滤波器设计

研究一类具有测量数据随机丢失以及网络拓扑结构随机切换的分布式$l_2-l_\infty$滤波器设计问题.在分布式滤波器网络,每个本地滤波器估计系统的状态不仅基于节点自身信息,而且利用网络拓扑中邻居节点的信息.首先,采用已知概率分布的二进制序列描述传感器测量数据的随机丢失,Markov链描述滤波器网络拓扑结构的切换;其次,构造一个Lyapunov函数来分析滤波误差系统的$l_2-l_\infty$性能,并研究其均方指数稳定性;再次,通过线性矩阵不等式(LMI)技术,给出分布式$l_2-l_\infty$滤波器的设计方法;最后, 通过数值例子验证所提方法的有效性.     

FDI攻击下互联电力系统的分布式安全状态估计

针对虚假数据注入(FDI)攻击下的多区域互联电力系统安全状态估计问题,提出一种分布式中间观测器,同时对各区域电力系统的状态、虚假数据注入攻击信号以及负载偏差进行估计.首先,通过将电力系统的状态和虚假数据注入攻击进行增广,得到等价的区域电力系统状态空间模型;然后,基于等价系统模型构建分布式中间观测器,对各个电力子系统分别进行安全状态估计,并设计补偿控制策略以降低虚假数据注入攻击及负载偏差带来的影响;最后,通过算例仿真验证所提出方法的可行性和有效性.     

NNCS混合容错控制方法

针对执行器任意失效故障,研究离散事件触发通讯机制下不确定NNCS主被动混合鲁棒$H_\infty$容错控制器设计问题,该控制器对外界有限能量扰动具有良好的抑制性能.首先,基于T-S模糊模型,建立离散事件触发通讯机制下不确定NNCS闭环故障模型;然后,基于$H_\infty$控制思想设计故障检测观测器并得到不确定NNCS鲁棒$H_\infty$容错控制设计准则;最后,通过Matlab仿真算例验证所设计的控制律对系统性能的改善以及事件触发条件的引入对网络资源的节约.     

基于观测器的发电机功角与故障估计

针对发电机功角与故障估计这个问题,提出一种利用观测器的方法.该方法通过对系统数学模型进行状态变换,将数学模型分为含故障与不合故障两部分.对不合故障部分设计观测器,然后经过状态变换可以得到功角信息.在故障估计过程中,通过增广误差系统设计增广观测器可以得到故障的幅值.最后通过Matlab仿真分析,验证基于观测器功角与故障估计方法的有效性,结果表明该方法具有速度快、误差小的优点.     

一种基于LPV系统的$H_infty$切换控制器设计方法

针对线性参数变化(LPV)系统提出一种切换控制器参数化设计方法.基于Youla参数化思想,将控制器设计过程分解为两个步骤.首先,设计一个中心控制器保证闭环系统的全局$H_\infty$性能;其次,将参数变化区域划分为若干个子区域,在每个子区域中将中心控制器进行线性分式变换,得到切换控制器自由参数的状态空间实现,将切换控制器转换为自由参数之间的切换.基于所提出的切换LPV控制器线性分式变换实现方法,不仅可以保证在任意切换的情况下子系统各自局部的$H_\infty$性能,而且可以保证整个闭环系统满足某一整体的$H_\infty$性能,并通过仿真结果验证了所提出方法的有效性.     

基于未知输入观测器的直流电机鲁棒故障估计

针对直流电机系统提出一种基于未知输入观测器(UIO)的鲁棒故障估计方法,同时估计系统中的执行器故障和传感器故障。首先,构建包含系统传感器故障的增广状态系统;然后,基于该增广系统提出一种新颖的UIO,并给出了该观测器的存在条件和多故障估计策略;同时,引入H_∞性能指标最大程度地抑制干扰对故障估计结果的影响;接着,给出观测器的设计条件和参数求解过程并将其转化为易于求解的线性矩阵不等式(LMI)的形式;最后,通过算例仿真和实验验证了该方法的有效性和可用性。     

具有容性负载的直流微电网系统分布式协同控制

针对一类具有容性负载的直流微电网系统, 提出了分布式协同控制方法. 具有容性负载的直流微电网是一类耦合动态互联非线性网络化系统, 可将DC-DC变换器在信息层视为智能体, 在每个子系统模块中, 引入容性负载电压观测器, 耦合并联非线性系统负载均衡控制设计问题可解耦成一阶积分器多智能体系统的输出一致性跟踪问题. 基于最近邻原则, 通过在控制器中引入比例、积分环节, 设计了增益可调的分布式协同PI控制律, 当有向图满足至少含有一棵生成树的条件下, 通过子系统间的局部交互, 可以实现负载均衡的目标. 通过分析增广系统矩阵的特征值证明了整个闭环系统的稳定性. 仿真和实验说明了所提出的控制方法的有效性及可行性.     

Distributed observer design for interconnected nonlinear systems with faults and disturbances based on dynamic event conditions

This study investigated the observer design schemes for interconnected nonlinear systems with actuator faults, sensor faults, external disturbances, and limited measured resources. A novel effective distributed estimation scheme is presented for the interconnected nonlinear system to estimate the states, faults, and lumped disturbances, simultaneously. To save communication resources and to improve information utilization, an adaptive event condition is designed in the sensor channel, and the triggered values are utilized to design the observer. Especially, to handle the sensor fault, the output is separated into two parts, and the estimation is realized with the help of a normal one. In the first part of this study, a class of interconnected nonlinear systems with partial loss of effectiveness of sensor fault is considered, and an event-based distributed estimation scheme is established. In the second part, a class of more universal feedback interconnected nonlinear with both partial loss sensor fault and bias sensor fault is investigated. An augment system is formulated by an augmented vector composed of state and sensor faults. And then the estimation scheme is realized by utilizing the presented event-based distributed observer. The convergence abilities of both the two conditions are proved and, finally, the estimation performances of the presented observer are verified by a numerical simulation system and an inverted pendulum system.     

基于反馈无源化的切换非线性系统H∞跟踪控制

针对切换非线性系统,提出一种基于反馈无源化的H_∞跟踪控制策略.首先,提出依赖状态切换的控制方法,在子系统不满足有界参考弱最小相位这一标准假设时,给出解决H_∞跟踪问题的充分条件,通过零状态可检测条件保证切换系统的内部稳定性,并利用无源不等式验证切换非线性系统满足H_∞跟踪性能;然后,提出依赖时间切换的跟踪策略,得到H_∞跟踪问题的可解性条件,该方法不依赖系统内部状态进行切换,将系统输出和参考信号之间的误差作为控制输入,并计算出切换系统满足的平均驻留时间;最后,给出仿真算例,以验证结果的正确性.     

Distributed sensor fault diagnosis in a class of interconnected nonlinear uncertain systems

In this paper, a distributed sensor fault detection and isolation (FDI) method is developed for a class of interconnected nonlinear uncertain systems. In the distributed FDI architecture, a FDI component is designed for each subsystem in the interconnected system. For each subsystem, its corresponding local FDI component is designed by utilizing local measurements and certain communicated information from neighboring FDI components associated with subsystems that are directly interconnected to the particular subsystem under consideration. Under certain assumptions, adaptive thresholds for distributed sensor fault detection and isolation in each subsystem are derived, ensuring robustness with respect to interactions among subsystems and system modeling uncertainty. Moreover, the fault detectability condition is rigorously investigated, characterizing the class of sensor faults in each subsystem that is detectable by the proposed distributed FDI method. Additionally, the stability and learning capability of the distributed adaptive fault isolation estimators is established. A simulation example of interconnected inverted pendulums mounted on carts is used to illustrate the effectiveness of the distributed FDI method.     

Distributed fault diagnosis in a class of interconnected nonlinear uncertain systems

In this article, a distributed fault detection and isolation (FDI) method is developed for a class of interconnected nonlinear uncertain systems. In the distributed FDI architecture, a FDI component is designed for each subsystem in the interconnected system. For each subsystem, its corresponding local FDI component is designed by utilising local measurements and certain communicated information from neighbouring FDI components associated with subsystems that are directly interconnected to the particular subsystem under consideration. Under certain assumptions, adaptive thresholds for distributed FDI in each subsystem are derived, ensuring robustness with respect to interactions among subsystems and system modelling uncertainty. Moreover, the fault detectability and isolability conditions are rigorously investigated, characterising the class of faults in each subsystem that are detectable and isolable by the proposed distributed FDI method. Additionally, the stability and learning capability of the local adaptive fault isolation estimators designed for each subsystem is established. A simulation example of interconnected inverted pendulums mounted on carts is used to illustrate the effectiveness of the method.     

Fast adaptive fault estimation and accommodation for nonlinear time‐varying delay systems

This paper studies the problem of fault estimation and accommodation for a class of nonlinear time‐varying delay systems using adaptive fault diagnosis observer (AFDO). A novel fast adaptive fault estimation algorithm that does not need the derivative of the output vector is proposed to enhance the performance of fault estimation. Meanwhile, a delay‐dependent criteria is obtained based on free weighting matrix method with the purpose of reducing the conservatism of the AFDO design. On the basis of fault estimation, an observer‐based fault‐tolerant controller is designed to guarantee the stability of the closed‐loop system. In terms of matrix inequality, we derive sufficient conditions for the existence of the adaptive observer and fault‐tolerant controller. Simulation results are presented to illustrate the efficiency of the proposed method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Event-triggered state estimation for T-S fuzzy affine systems based on piecewise Lyapunov-Krasovskii functionals

This paper investigates the problem of event-triggered ${\rm H}_\infty$ state estimation for Takagi-Sugeno (T-S) fuzzy affine systems. The objective is to design an event-triggered scheme and an observer such that the resulting estimation error system is asymptotically stable with a prescribed ${\rm H}_{\infty}$ performance and at the same time unnecessary output measurement transmission can be reduced. First, an event-triggered scheme is proposed to determine whether the sampled measurements should be transmitted or not. The output measurements, which trigger the condition, are supposed to suffer a network-induced time-varying and bounded delay before arriving at the observer. Then, by adopting the input delay method, the estimation error system can be reformulated as a piecewise delay system. Based on the piecewise Lyapunov-Krasovskii functional and the Finsler''s lemma, the event-triggered ${\rm H}_{\infty}$ observer design method is developed. Moreover, an algorithm is proposed to co-design the observer gains and the event-triggering parameters to guarantee that the estimation error system is asymptotically stable with a given disturbance attenuation level and the signal transmission rate is reduced as much as possible. Simulation studies are given to show the effectiveness of the proposed method.     

Robust delay dependent fault estimation for a class of interconnected nonlinear time delay systems

This paper focuses on the problem of fault estimation for a class of interconnected nonlinear systems with time varying delays. In contrast to the common assumption imposed on the problem in most literature, here, there is no need for the delay rate to be less than one. Both actuator and component faults are considered within the general fault model invoked as multiplicative faults in this study. Robust adaptive observers are used to detect and estimate simultaneously the states and the parameter faults in each subsystem. The designed observers ensure a prescribed H _∞ performance level for the fault estimation error, irrespective of the uncertainties which are assumed here to be the unknown interconnections between the subsystems. With the aid of H _∞ performance index, the common assumption regarding the observer matching condition is no longer required. Sufficient conditions for asymptotic stability of the observers are derived via a matrix inequality approach with the aid of LyapunovKrasovskii function. Finally, a simulation example is presented to show the validity and feasibility of the proposed method.