基于未知输入观测器方法的非线性切换系统故障检测

基于非线性未知输入观测器方法对一类离散时间非线性切换系统的故障检测问题进行了研究。给出了两种不同结构的非线性未知输入观测器。针对每一种观测器都考虑了两种切换信号:任意时间切换信号和满足平均驻留时间的切换信号。在任意切换信号下,使用了切换Lyapunov函数的方法来设计非线性未知输入观测器的参数;在满足平均驻留时间切换信号下,使用了多Lyapunov函数方法进行观测器参数的设计。然后利用已知的非线性未知输入观测器,得到残差生成器,进而实现故障检测。通过数值仿真例子,验证了故障检测方法的有效性。     

变体飞行器连续平滑切换LPV控制

针对一类翼展可变飞行器的控制问题,提出了一种连续平滑切换线性变参数(linear parameter varying, LPV)控制器的设计方法。将变体飞行器建模成以翼展变形率为时变参数的LPV系统,通过对时变参数进行具有重叠特性的区间划分,设计平滑切换控制器。结合参数依赖的多李雅普诺夫函数和平均驻留时间方法,给出了保证切换LPV系统指数稳定的充分条件。由于考虑了时变参数的渐变特性,使得系统的切换律没有平均驻留时间的限制,降低了结论的保守性。仿真结果表明,运用所设计的控制器,当翼展连续变化时,变体飞行器状态稳定且切换过程平滑,控制性能良好。     

基于异步切换的飞行器网络控制系统故障检测

针对网络化飞行器故障检测系统在多工作点间切换情况,考虑时延和丢包导致的滤波器切换时刻滞后于飞行器模型切换时刻问题,提出一种基于异步切换系统的故障检测算法。将网络环境下大包线内多工作点飞行器建模为异步切换系统,基于李亚普诺夫函数和平均驻留时间法,给出了具有异步切换形式的故障检测系统全局一致渐近稳定的充分条件,进一步利用线性矩阵不等式（linear matrix inequation, LMI）工具求取滤波器参数。数值仿真验证并分析了所提方法的有效性。     

Optimal Switching Integrity Attacks on Sensors in Industrial Control Systems

In this article, an optimal switching integrity attack problem is investigated to study the response of feedback control systems under attack. The authors model the malicious attacks on sensors as additive norm bounded signals. The authors consider an attacker who is only capable of launching attacks to limited number of sensors once a time and changing the combinations of attacked sensors all over the time. The objective of this paper is to find the optimal switching sequence of these combinations and the optimal attack input. The authors solve this problem by transforming it into a traditional optimal control problem with new control variables vary continuously in the range [0, 1]. The optimal solutions of the new control variables are of bang-bang-type. Therefore, an algebraic switching condition and an optimal attack input can be obtained. Finally, numerical results are provided to illustrate the effectiveness of the methods.     

具有瞬时耦合及通讯时滞的调和振子同步动力学

针对具有局部瞬时耦合及通讯延时的调和振子动力网络系统,给出了一种分布式同步算法。分别在无向固定拓扑和切换拓扑两种情形下给出了同步态的解析表达式,以及耦合系统的解析解,并给出了一些一般而简单的同步化准则。结果表明网络化的调和振子在比较弱的瞬时网络连通条件下,可以达到同步状态。数值模拟表明所给理论结果的正确性和有效性。     

不确定切换系统基于切换时间的动态输出反馈鲁棒H∞控制

借助平均驻留时间方法，讨论了一类不确定切换系统的动态输出反馈鲁棒H_∞控制问题。利用多Lyapunov函数法，以线性矩阵不等式的形式给出了使得该类闭环系统的动态输出反馈控制器存在的充分条件。同时,构建了基于切换驻留时间的切换律。在综合考虑最优化干扰抑制性能指标γ和求解的简便性后，给出了动态输出反馈控制器的设计算法。进一步的，将所得结果推广到任意切换律的情况。     

近空间飞行器鲁棒自适应Backstepping控制

针对变体近空间飞行器(near space vehiele, NSV)大包络、多模态的特性,研究其姿态的鲁棒自适应跟踪控制问题。首先,提出标称变体NSV切换非线性系统的单一且光滑主控制器设计方法,以解决因飞行模态切换引起的主控制舵面跳变。其次,针对切换瞬间复合干扰存在不连续的问题,给出一组同步切换的改进干扰观测器设计方法。将改进干扰观测器的输出与光滑的主控制律相结合组成不确定变体NSV切换非线性系统的复合控制器。采用平均驻留时间分析法证明所提出的控制方法可以保证闭环不确定变体NSV切换非线性系统的稳定性。最后,仿真结果验证了所提方法的有效性。     

Consensus for Heterogeneous Multi-Agent Systems with Directed Network Topologies

In this paper, the consensus problem for heterogeneous multi-agent systems composed of first-order and second-order agents is investigated with directed network topologies. Based on a system transformation method, this consensus problem is turned into a consensus problem for homogeneous multi-agent systems. With certain assumption on the control parameters, firstly, necessary and sufficient condition for consensus is proposed with fixed topology. Secondly, sufficient condition is proposed for heterogeneous multi-agent systems to achieve consensus with switching topologies. Finally, simulation examples are presented to verify the effectiveness of the theoretical results.     

Distributed tracking control of second-order multi-agent systems under measurement noises

This paper considers a leader-following tracking control problem for second-order multiagent systems（MASs） under measurement noises and directed communication channels.It is assumed that each follower-agent can measure the relative positions and velocities of its neighbors in a noisy environment.Based on a novel velocity decomposition technique,a neighbor-based control law is designed to realize local control strategies for these continuous-time agents.It is shown that the proposed consensus protocol can guarantee that all the follower-agents track the active leader.In addition,this result is extended to a more general case with switching topologies.Finally,a numerical example is given for illustration.     

固定多波束扩频测控信号同步实现技术

针对固定多波束扩频测控信号同步和波束扫描问题,提出了一种快速同步及波束扫描实现方法。该方法通过时分复用结构的部分相关匹配滤波和延迟锁定环,可实现大频偏情况下的快速伪码同步,剥离伪码后的信号经去调制处理后,结合基于快速傅里叶变换的前向频率估计和判决反馈锁频锁相环,实现跟踪阵列波束载波同步及波束切换过程中跟踪阵列波束及切换阵列波束的同时跟踪。仿真结果表明,该实现方法能满足高动态多波束扩频测控信号快速同步、快速扫描和切换过程连续解调的要求。     

Data-Driven Leader-Follower Output Synchronization for Networked Non-Linear Multi-Agent Systems with Switching Topology and Time-Varying Delays

This paper studies the output synchronization problem for a class of networked non-linear multi-agent systems with switching topology and time-varying delays. To synchronize the outputs, a leader is introduced whose connectivity to the followers varies with time, and a novel data-driven consensus protocol based on model free adaptive control is proposed, where the reference input of each follower is designed to be the time-varying average of the neighboring agents’ outputs. Both the case when the leader is with a prescribed reference input and the case otherwise are considered. The proposed protocol allows for time-varying delays, switching topology, and does not use the agent structure or the dynamics information implicitly or explicitly. Sufficient conditions are derived to guarantee the closed-loop stability, and conditions for consensus convergence are obtained, where only a joint spanning tree is required. Numerical simulations and practical experiments are conducted to demonstrate the effectiveness of the proposed protocol.     

Stabilization of switched linear systems with constrained inputs

The stabilization of switched linear systems with constrained inputs(SLSCI) is considered. The authors design admissible linear state feedbacks and the switching rule which has a minimal dwell time(MDT) to stabilized the system.First,for each subsystem with constrained inputs,a stabilizing linear state feedback and an invariant set of the closed-loop system are simultaneously constructed, such that the input constraints are satisfied if and only if the closed-loop system’s states lie inside this set.Then,by constructing a quadratic Lyapunov function for each closed-loop subsystem,an MDT is deduced and an MDT-based switching strategy is presented to ensure the stability of the switched system.     

Consensus control for leader-following multi-agent systems with measurement noises

<正> This work is concerned with consensus control for a class of leader-following multi-agentsystems (MASs).The information that each agent received is corrupted by measurement noises.Toreduce the impact of noises on consensus,time-varying consensus gains are adopted,based on whichconsensus protocols are designed.By using the tools of stochastic analysis and algebraic graph theory,asufficient condition is obtained for the protocol to ensure strong mean square consensus under the fixedtopologies.This condition is shown to be necessary and sufficient in the noise-free case.Furthermore,by using a common Lyapunov function,the result is extended to the switching topology case.     

无线自组网的自适应同步技术研究

研究了无线自组网中动态拓扑下节点时间同步存在的问题,提出了一种自适应的时间同步算法。通过采用基于发送-接收模式的同步方法建立节点之间的时延关系表,运用局部加权回归对洪泛时间同步协议中的时间戳进行拟合,再对拟合曲线估计的时间和由节点的动态时延表得到的时间进行综合分析,完成节点时间同步。仿真结果表明,在动态无线自组网中,与传统的同步算法相比,所提算法使得同步过程所需传输的分组数量平均降低了30%左右,全网节点间的时钟同步精度平均提高了26%左右。     

Distributed quantized consensus for agents on directed networks

Communication bandwidth and network topology are two important factors that affect performance of distributed consensus in multi-agent systems. The available works about quantized average consensus assume that the adjacency matrices associated with the digraphs are doubly stochastic, which amounts to that the digital networks are balanced. However, this assumption may be unrealistic in practice. In this paper, without assuming double stochasticity, the authors revisit an existing quantized average consensus protocol with the logarithmic quantization scheme, and investigate the quantized consensus problem in general directed digital networks that are strongly connected but not necessarily balanced. The authors first derive an achievable upper bound of the quantization precision parameter to design suitable logarithmic quantizer, and this bound explicitly depends on network topology. Subsequently, by means of the matrix transformation and the Lyapunov techniques, the authors provide a testable condition under which the weighted average consensus can be achieved with the proposed quantized protocol.     

Exponential stability of impulsive jump linear systems with Markov process

The exponential stability is investigated for a class of continuous time linear systems with a finite state Markov chain form process and the impulsive jump at switching moments. The conditions, based on the average dwell time and the ratio of expectation of the total time running on all unstable subsystems to the expectation of the total time running on all stable subsystems, assure the exponential stability with a desired stability degree of the system irrespective of the impact of impulsive jump. The uniformly bounded result is realized for the case in which switched system is subjected to the impulsive effect of the excitation signal at some switching moments.     

基于拟牛顿算法的自由下落猫的非完整运动规划

研究猫在自由下落时四肢着地的姿态运动规划问题。自由落体的猫在空中转体运动由于角动量守恒，姿态运动方程呈现为非完整形式。系统的控制问题可转化为无漂移系统的非完整运动规划问题。首先导出由两个对称刚体组成的力学模型的非完整姿态运动方程。利用最优控制理论和最优化技术，采用输入参数化的方法将连续的最优控制问题转化为离散的最优控制问题。基于拟牛顿方法，给出自由落体猫在空中姿态非完整运动规划算法。最后对自由落体猫作了数值仿真试验，仿真结果验证了该算法的有效性。     

Consensus problem of second-order multi-agent systems with time-varying communication delay and switching topology

Leader-following stationary consensus problem is investigated for the second-order multi-agent systems with timevarying communication delay and switching topology.Based on Lyapunov-Krasovskii functional and Lyapunov-Razumikhin functions respectively,consensus criterions in the form of linear matrix inequality (LMI) are obtained for the system with time-varying communication delays under static interconnection topology converging to the leader’s states.Moreover,the delay-dependent consensus criterion in the form of LMI is also obtained for the system with time-invariant communication delay and switching topologies by constructing Lyapunov-Krasovskii functional.Numerical simulations present the correctness of the results.     

多智能体系统的有限时间跟踪控制

基于领导-跟随者模型研究了多智能体系统的有限时间跟踪控制问题。针对领导者状态是时变的情况,提出了一类非线性有限时间跟踪控制算法,在固定网络拓扑结构下,利用Lyapunov有限时间稳定性理论和矩阵理论分析,得到了该算法使得系统中跟随者状态在有限时间内与领导者状态达到一致的充分条件;在切换网络拓扑结构下,提出了一类有限时间跟踪控制算法,在领导者的状态是时不变的情况下,给出了该算法使得系统实现有限时间跟踪控制的充分条件。仿真实例验证了所提出两类算法的有效性。     

Cluster Synchronization in a Complex Dynamical Network with Two Nonidentical Clusters

This paper further investigates cluster synchronization in a complex dynamical network with two-cluster. Each cluster contains a number of identical dynamical systems, however, the subsystems composing the two clusters can be different, i.e., the individual dynamical system in one cluster can differ from that in the other cluster. Complete synchronization within each cluster is possible only if each node from one cluster receives the same input from nodes in other cluster. In this case, the stability condition of one-cluster synchronization is known to contain two terms： the first accounts for the contribution of the inner-cluster coupling structure while the second is simply an extra linear term, which can be deduced by the ＂same-input＂ condition. Applying the connection graph stability method, the authors obtain an upper bound of input strength for one cluster if the first account is known, by which the synchronizability of cluster can be scaled. For different clusters, there are different upper bound of input strength by virtue of different dynamics and the corresponding cluster structure. Moreover, two illustrative examples are presented and the numerical simulations coincide with the theoretical analysis.