带滤波的无线传感器网络的H∞控制

本文研究了基于滤波的无线传感器网络的H∞控制问题.首先建立了无线传感器网络的模型,然后使用稳态Kalman滤波器对多个传感器节点的输出信号进行滤波,将滤波后的信号作为无线传感器网络系统的反馈输出,并通过建模和分析得到带干扰的线性离散切换系统模型.最后设计了切换控制器,并基于Lyapunov函数给出了在任意切换条件下使该切换系统满足H∞控制的条件.仿真结果验证了该方法和结果的可行性.     

一种802.16网络中的移动IPv6快速切换方案

移动IPv6是IETF提出来解决网络层移动性问题的标准,但移动IPv6在切换过程中存在无法接受的切换延时和数据包丢失,无法满足实时应用的要求.通过对802.16链路层切换过程的研究,本文提出了一种802.16网络中的移动IPv6快速切换方案,该方案利用链路层的触发信号和隧道减少移动IPv6的移动检测,转交地址配置和绑定更新的时延以及切换过程中的数据包丢失.     

一类时滞切换奇异系统的指数H∞滤波器研究

研究了一类时滞切换奇异系统的指数H∞滤波问题.为了提高控制系统的稳定性,解决系统的指数H∞滤波的难点问题,提出利用平均驻留时间方法,首先给出了使得滤波误差系统在切换信号下具有指数可容许性并且具有相应的H∞性能指标的条件,然后以一组线性矩阵不等式的形式给出了期望滤波器存在的充分条件,并给出了相应的滤波器参数求解.所设计的指数H∞滤波器不但保证系统参数不确定时闭环系统指数稳定,而且满足所期望的H∞性能指标.最后用数值仿真实例来说明设计方法的有效性和可行性.     

移动IPv4切换时间特性的实验与分析

通过将切换过程进行小粒度解析总结出切换时延的组成,针对各类耗时在自行开发的系统上进行了实验。实验结果表明：目前移动IP切换时延主要取决于协议数据包的传输时间和在进行协议栈处理以前等待路由（代理）广告的时间,缩短这两部分时间是提高移动IP切换速度的关键。     

基于异步切换多胞系统的网络化飞行器故障检测

本文研究了存在时变短时延和随机丢包的大包线网络化飞行器故障检测问题.首先,采用切换多胞系统描述飞行动态,并提出了一种局部重叠多胞划分方式以较低设计保守性.然后,借助泰勒级数展开和伯努利分布将时延和丢包转化为多胞系统参数,并构建了切换参数依赖故障检测滤波器.同时,考虑滤波器切换指令及多胞加权参数更新滞后引起的异步切换问题,基于切换参数依赖Lyapunov函数和平均驻留时间方法分析了系统的稳定性和l2性能,并以LMI形式给出了滤波器存在的充分条件.最后,以HiMAT(highly maneuverable technology)飞行器为例验证了所提方法的有效性.     

具有状态时滞的离散时间切换系统的H∞ 滤波器设计: 依赖状态的切换方法

讨论一类时滞离散时间切换系统的H∞滤波器的设计问题.首先,当所有子系统都稳定时,基于切换Lyapunov函数和Finsler引理,得到了滤波误差系统渐近稳定且具有指定的H∞性能指标的充分条件,即使切换系统的每个子系统均不稳定,通过利用多Lyapunov函数方法和依赖状态的切换技术仍能保证切换系统稳定;然后,设计了H∞滤波器,并得到滤波误差系统满足指定的H∞性能指标的充分条件;最后,通过数值算例验证了所提出方法的有效性.     

具有双通道数据包丢失的Delta算子系统故障检测

研究同时存在双通道数据包丢失和时变时延的Delta算子网络控制系统（NCSs）故障检测问题.假定数据包丢失发生在控制器到执行器、传感器至控制器的数据传输过程中，并且利用两个相互独立的伯努利随机变量描述是否发生丢包.将上述的NCSs建模为网络切换系统，提出任意切换律下故障检测滤波器的设计方法.利用线性矩阵不等式（LMIs）方法、Lyapunov-Krasovskii泛函和平均驻留时间等得出所考虑的网络切换系统具备指数均方稳定性的充分条件.证明了所用的网络切换系统满足H_∞性能，并推导出了滤波器参数的显式表达.数值仿真结果验证了所提方法的有效性.     

基于网络的离散切换时滞系统故障检测和控制器协同设计

针对带有时变时滞和数据包丢失的离散网络切换控制系统,提出在任意切换信号下的闭环故障检测和控制器协同设计策略;基于平均驻留时间和李雅普诺夫(LKF)方法,给出并证明离散切换时滞动态系统指数均方稳定且具有满意的H_∞性能指标的充分条件;将离散网络切换时滞系统的控制器和故障检测滤波器的参数求解转化为可行的凸优化问题,确保残差和故障估计误差尽可能小.仿真实验结果验证了所提出方法的有效性.     

基于局部交叠异步切换的网络控制系统故障检测

针对存在时变短时延和丢包的网络控制系统故障检测问题,将非线性对象建模为线性切换系统.考虑工程中存在的局部交叠切换律,将切换系统划分为若干局部交叠切换于系统.同时,考虑滤波器切换滞后引起的异步切换问题,进一步将系统增广为局部交叠异步切换系统.在此基础上,结合公共Lyapunov函数和平均驻留时间方法,以LMI形式给出检测滤波器设计方法.最后,通过某网络化飞行器的全包线飞行验证了所提出方法的有效性.     

IEEE802.11网络中过后注册切换机制实现及性能分析

首先对移动切换过程和过后注册切换机制进行分析.在IEEE802.11网络上,对管理帧的信息单元进行扩展来构造二层触发消息,并在Linux上实现了过后注册切换机制.最后从丢包和切换时延两方面对过后注册切换机制进行性能分析.分析结果表明,过后注册切换机制明显降低了切换时延,减少了数据包的丢失.     

Exponential H∞ Filtering for Discrete‐Time Switched State‐Delay Systems Under Asynchronous Switching

The exponential H_∞ filtering problem of discrete‐time switched state‐delay systems under asynchronous switching is considered in this paper. The objective is to design a full‐order or reduced‐order switched filter guaranteeing the exponential stability with the weighted H_∞ performance of the filtering error system. A sufficient condition for the exponential stability with the weighted H_∞ performance of the filtering error system is provided based on delay‐dependent multiple Lyapunov‐Krasovskii functionals. The gains of the filter can be obtained by solving a set of linear matrix inequalities. A numerical example is presented to demonstrate the effectiveness of the developed results.     

数字化开关电容滤波技术应用

介绍了数字化开关电容滤波技术,并设计了可以通过改变开关时钟频率来自由调整中心频率的开关电容带阻滤波器,使中心频率具有很高的精度和稳定度。提出的抗混叠滤波技术能有效消除高频混叠和噪声干扰。在中心频率为200Hz,Q值为3的条件下,陷波深度可达到29dB。     

任意切换时间下的二维线性混合系统的滑模控制

由于混合系统的复杂性,设计出能保证混合系统在任意切换时间下都能稳定的控制是比较困难的。为了突出滑模控制设计的思想,文章针对一类二维线性混合系统,提出通过确保混合系统实现滑动模的充分条件来保证系统的稳定性,并得到相应的控制律。仿真结果表明了该控制律的有效性。     

Asymptotic switched composite adaptive control with application to robotic interaction tasks

This article proposes a new switched adaptive control design for uncertain switched systems with composite (time-driven and state-dependent) switching and shows its applicability in switched impedance control. A composite switched adaptive control design, consisting of the direct switched adaptive control and the indirect switched adaptive control counterpart, is developed to improve the control performance. Specifically, a new stability condition for composite switching is proposed by making use of differential matrix equations and Sylvester matrix equations, which are a generalization of Lyapunov matrix equations. The design results in a time-varying multiple Lyapunov function that is decreasing at the switching instants. From the theoretical point of view, the relevance of this work is the construction of the adaptive laws that guarantee asymptotic tracking error and asymptotic estimation for the direct and indirect switched adaptive control loops, respectively. From the practical point of view, the relevance of this work is validated in a new switched impedance control for the robot interaction with uncertain and discontinuous environments.     

Robust reliable sampled-data control for switched systems with application to flight control

This paper addresses the robust reliable stabilisation problem for a class of uncertain switched systems with random delays and norm bounded uncertainties. The main aim of this paper is to obtain the reliable robust sampled-data control design which involves random time delay with an appropriate gain control matrix for achieving the robust exponential stabilisation for uncertain switched system against actuator failures. In particular, the involved delays are assumed to be randomly time-varying which obeys certain mutually uncorrelated Bernoulli distributed white noise sequences. By constructing an appropriate Lyapunov–Krasovskii functional (LKF) and employing an average-dwell time approach, a new set of criteria is derived for ensuring the robust exponential stability of the closed-loop switched system. More precisely, the Schur complement and Jensen's integral inequality are used in derivation of stabilisation criteria. By considering the relationship among the random time-varying delay and its lower and upper bounds, a new set of sufficient condition is established for the existence of reliable robust sampled-data control in terms of solution to linear matrix inequalities (LMIs). Finally, an illustrative example based on the F-18 aircraft model is provided to show the effectiveness of the proposed design procedures.     

Sojourn-probability-dependent H∞ control for networked switched systems under asynchronous switching

This paper considers H_∞ controller design for a class of networked switched discrete systems under asynchronous switching. The sojourn probability information – the probability of the switched systems staying in each subsystem – is first used to rebuild the networked switched systems. Also, a time-varying lag, depending on both the network-induced delays and switching signals, is taken into consideration between the switching instants of the controllers and systems model. By considering both sojourn probability information and asynchronous switching, a new kind of networked switched system model is proposed, wherein a set of random variables are proposed to describe the sojourn probabilities of the subsystems. Then, stability analysis and H_∞ performance analysis under asynchronous switching are derived. It should be noted that the system performance depends not only on the time-varying lag, but also on the sojourn probabilities. Finally, an example is given to illustrate the effectiveness of the proposed approach.     

Simultaneous state and output disturbance estimations for a class of switched linear systems with unknown inputs

The paper considers the issues of state estimation and output disturbance reconstruction for a class of switched linear systems with unknown inputs. A singular switched system is derived from the original switched system by taking the output disturbance as a part of a new extended state vector. For the constructed singular switched system, a robust sliding-mode switched observer which can not only estimate the states of original switched system but also reconstruct output disturbances is proposed, where the switching of the observer is synchronous with that of the switched system. A sufficient condition is provided to guarantee the existence of the switched observer by the feasibility of an optimisation problem with linear matrix inequality constraint, and the corresponding switching signal with average dwell time is designed such that the convergence of the estimation error system is proven to be exponential. Based on the state estimation of singular switched system, the methods of state estimation and output disturbance reconstruction of original switched system are proposed. Finally, the simulation results confirm the predicted performance of the proposed methods.     

Optimal‐switched extended H∞ filter for nonlinear systems with stochastic uncertainties

The extended H_∞ filter (EH_∞F) is a conservative solution with infinite‐horizon robustness for the state estimation problem regarding nonlinear systems with stochastic uncertainties, which leads to excessive costs in terms of filtering optimality and reduces the estimation precision, particularly when uncertainties related to external disturbances and noise appear intermittently. In order to restore the filtering optimality lost due to the conservativeness of the EH_∞F design, we developed an optimal‐switched (OS) filtering mechanism based on the standard EH_∞F to obtain an optimal‐switched extended H_∞ filter (OS‐EH_∞F). The OS mechanism has an error‐tolerant switched (ETS) structure, which switches the filtering mode between optimal and H_∞ robust by setting a switching threshold with redundancy to uncertainties, and a robustness‐optimality cost function (ROCF) is introduced to determine the threshold and optimize the ETS structure online. The ROCF is the weighted sum of the quantified filtering robustness and optimality. When a weight is given, the proposed OS‐EH_∞F can obtain the optimal state estimates while maintaining the filtering robustness at an invariant ratio. A simulation example of space target tracking has demonstrated the superior estimation performance of the OS‐EH_∞F compared with some other typical filters, thereby verifying the effectiveness of using the weight to evaluate the estimation result of the filters.     

跳变约束下马尔可夫切换非线性系统滤波

针对系统状态演化多模不确定性和状态约束多样性,本文提出了跳变约束下马尔可夫切换非线性系统的交互式多假设估计方法.定义了包含跳变马尔可夫参数可能取值的假设集,根据最优贝叶斯滤波,推导出状态与假设的后验概率递推更新.基于统计线性回归线性化非线性函数,利用伪量测法,将线性化的约束扩维到真实量测中,给出了非线性系统滤波的近似解析最优解.最终给出所提算法的稀疏网格积分近似最优估计实现.在交叉道路机动目标跟踪仿真场景中,所提算法的滤波精度优于基于泰勒展开的交互式多模型算法,基于统计线性回归的交互式多模型算法,以及基于泰勒展开的非线性系统约束滤波算法.     

一类线性连续切换系统的迭代学习控制

针对有限时间区间内执行重复控制任务的线性连续切换系统,考虑基于迭代学习的跟踪控制问题.假设线性切换系统的切换率在时间域内是任意的,提出该类系统的D型迭代学习控制算法.理论分析表明,当学习增益矩阵满足一定的条件时,D型迭代学习控制算法可以保证切换系统的实际输出在整个运行区间上一致收敛于期望输出,实现完全跟踪控制.数值仿真进一步验证了方法的有效性.