一类高阶线性系统的分层控制

近年来, 一种基于系统层次结构的分层控制方法发展了起来, 它主要针对的是高阶复杂系统. 为了分析和控制这类系统, 我们首先根据需要构建一个合适的低阶抽象系统, 然后在此基础上分析和设计原始系统控制律, 即所谓的接口函数. 本文将此方法用于一类高阶线性系统的稳定控制问题, 并得到了相应的控制律. 最后, 算例部分的仿真结果说明了这种方法的有效性.     

基于本体的分层抽象模型

KRA表示模型给出了对物理世界W进行形式化建模的一般框架。在扩展后的广义KRA模型中引入本体概念,将抽象对象库扩展为本体类,在本体类中实现KRA模型框架中的感知层、语言层和理论层的知识共享和重用,简化了KRA模型的表示。分别定义了作用在物理世界W和本体类上的3种本体抽象算子(集):基本本体抽象算子、实体本体抽象算子集和连接本体抽象算子集,并给出了本体类之间的映射关系,通过这种映射关系能够实现模型抽象和模型还原。对本体类的抽象度进行形式化的定义,并给出了相关定理,指出在这样的框架中利用抽象映射可以自动构建物理世界W的抽象度不同的模型。     

多机并发系统中通信模型分层抽象的方法

针对多机并发系统的复杂性,为了辅助用户能从多个角度和层次全面地理解并发系统,就需要逆向产生出能够反映软件系统框架结构的高层架构。基于此本文以进程为边界,提出了一种分层抽取多机并发系统通信模型的方法。此方法基于反射和开放编译的植入机制来获取所需要的动态信息,在此基础上运用分层抽象的策略,分别从系统、节点、进程三个层次对多机并发系统的通信结构和设计结构进行逆向恢复,最后对该方法进行系统的实验研究。结果表明,分层抽象所得到并发系统的通信模型能够正确、有效地反映系统设计时的高层架构关系。     

基于系统中心本体的分层抽象模型

本体类分层关系的确定,使得能够利用不同抽象度本体类之间的抽象映射自动构建物理世界的分层模型。根据本体类型的不同将已有的本体类定义为对象本体类(Object based Ontology Class),并对流片段(Flow Fragment)的概念加以扩展,提出以系统为中心的流本体类(Flow-based Ontology Class)的概念。定义了流片段的行为不可区分性,从两个不同的方向讨论了流本体类的分层表示:一是对构成流本体类的流片段的不同抽象度分层扩展;二是对构成流本体类的不可区分的流片段的合并分层扩展。给出了流本体类的分层过程,定义了系统级的映射关系,即流片段之间的抽象映射,指出该映射为基于系统中心本体的模型抽象分层过程提供了直接的转换运算。并且,流本体类的分层关系的确定也为基于系统中心本体的模型设计任务提供了可共享和重用的机制。     

线性大系统递阶控制的一种新型逼近方法

将文[1]提出的按段多重契比雪夫多项式系(PMCP)应用于线性大系统递阶控制算法的逼近计算,将动态递阶控制转化为静态递阶优化,获得了一种新型逼近算法.仿真结果表明了该算法的有效性.     

线性时变大系统递阶控制的一种新方法

根据正交函数逼近理论，本文提出了解决时变大系统递阶控制的一种新型逼近算法。文中首先简单介绍了ＰＭＣＰ，同时给出了一些新的研究结果；研究了其在两点边值问题中的逼近解。动态大系统的逼近控制分为二级，第一级是子系统的优化问题，采用ＰＭＣＰ逼近技术解决；第二级为协调级，协调向量也通过ＰＭＣＰ逼近变换求解，这样使问题得到大为简化，不但算法简单，便于计算机运算，而且逼近精度高。数值仿真例子表明了本文提出的算法     

基于近似模拟的多智能体系统分布式层次控制设计

本文主要探讨基于近似模拟的多智能体系统分布式层次控制的设计问题。为降低问题复杂度,首先建立了一个简单的抽象系统指导各智能体,继而讨论这一抽象系统和多智能体之间的模拟关系。借助于该抽象系统,给出多智能体系统完成一类协调任务的分布式层次控制器。同时利用模拟函数和共同Lyapunov函数,进一步分析了多个体系统在切换拓扑下的集体行为。     

Group-Consensus of Hierarchical Containment Control for Linear Multi-Agent Systems

The existing containment control has been widely developed for several years, but ignores the case for large-scale cooperation. The strong coupling of large-scale networks will increase the costs of system detection and maintenance. Therefore, this paper is concerned with an extensional containment control issue, hierarchical containment control. It aims to enable a multitude of followers achieving a novel cooperation in the convex hull shaped by multiple leaders. Firstly, by constructing the three-layer topology, large-scale networks are decoupled. Then, under the condition of directed spanning group-tree, a class of dynamic hierarchical containment control protocol is designed such that the novel group-consensus behavior in the convex hull can be realized. Moreover, the definitions of coupling strength coefficients and the group-consensus parameter in the proposed dynamic hierarchical control protocol enhance the adjustability of systems. Compared with the existing containment control strategy, the proposed hierarchical containment control strategy improves dynamic control performance. Finally, numerical simulations are presented to demonstrate the effectiveness of the proposed hierarchical control protocol.      

智能微电网的分层控制

本文介绍了分层控制的理论基础,在将正确有效的下垂控制作为智能微电网一级控制的基础上,搭建了二级控制器,组成了分层控制。通过分析MATLAB／Simulink仿真结果,验证了由二级控制恢复微电网频率和电压的有效性和可行性。     

Reliable State Feedback Control Synthesis For Uncertain Linear Systems

This paper is concerned with the problem of designing reliable state‐ feedback control for a class of uncertain linear systems with norm bounded uncertainty. A procedure for designing reliable state‐feedback control is presented for the case of actuator faults that can be modeled by a scaling factor. In the design, the performance of the normal system (without fault) is optimized, as the considered system operates under the normal condition most of the time. In addition, when actuator faults occur, the closed‐loop system retains robust stability and satisfies a known quadratic performance bound. A numerical example is provided to illustrate the effectiveness of the proposed design method.     

一类线性时变系统的输出反馈控制

基于线性时不变系统能控能观标准型变换及非线性系统高增益观测器方法,本文研究了一类线性时变系统 的输出反馈控制问题. 通过引入时变的状态变量坐标变换,分别设计了线性时变系统的状态反馈控制器、状态观测器以及基于 状态观测器的输出反馈控制器. 进一步地,本文分别证明了观测器动态误差是渐近收敛于零的,而状态反馈控制器以及输出反馈控制器可以 保证闭环系统的渐近稳定性.     

一种自适应双反馈递阶控制系统

本文以水厂控制为背景,研究一类受随机扰动作用、以时滞动态过程为关联约束的大系统最优控制问题,提出一种自适应双反馈递阶控制方法.它既能象闭环控制那样满足约束条件、改善性能指标,又能象开环控制那样,计算量小,收敛性好.     

具有结构不确定性的线性反馈控制系统的鲁棒稳定性

本文研究了具有结构不确定性(Structured Uncertainty)因素的反馈控制系统的鲁棒稳定性问题,对于一个普通的补偿器,给出了闭环系统鲁棒稳定的充要条件,当补偿器满足某些假设条件时,得出了闭环系统鲁棒稳定的有限检验的充分必要条件.     

一种层次视频摘要生成方法

视频摘要是视频内容的一种压缩表示方式。为了能够更好地浏览视频，提出了一种根据浏览或检索的粒度不同来建立两种层次视频摘要(镜头级和场景级)的思想，并给出了一种视频摘要生成方法：首先用一种根据内容变化自动提取镜头内关键帧的方法来实现关键帧的提取；继而用一种改进的时间自适应算法通过镜头的组合来得到场景；最后在场景级用最小生成树方法提取代表帧。由于关键帧和代表帧分别代表了它们所在镜头和场景的主要内容，因此它们的序列就构成了视频总结。一些电影视频片段检验的实验结果表明，这种生成方法能够较好地提供粗细两种粒度的视频内容总结。     

虚拟控制增益函数未知的随机非线性系统模糊自适应控制

The problem of track control is studied for a class of strict-feedback stochastic nonlinear systems in which unknown virtual control gain function is the main feature. First, the so-called stochastic LaSalle theory is extended to some extent, and accordingly, the results of global ultimate boundedness for stochastic nonlinear systems are developed. Next, a new design scheme of fuzzy adaptive control is proposed. The advantage of it is that it does not require priori knowledge of virtual control gain function sign, which is usually demanded in many designs. At the same time, the track performance of closed-loop systems is improved by adaptive modifying the estimated error upper bound. By theoretical analysis, the signals of closed-loop systems are globally ultimately bounded in probability and the track error converges to a small residual set around the origin in 4th-power expectation.     

Fixed-Time Stabilization of a Class of Strict-Feedback Nonlinear Systems via Dynamic Gain Feedback Control

This paper presents a novel fixed-time stabilization control(FSC) method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics. The key feature of the proposed method is the design of two dynamic parameters.Specifically, a set of auxiliary variables is first introduced through state transformation. These variables combine the original system states and the two introduced dynamic parameters, facilitating the closed-loop system stability analyses. Then, the two dyna...     

具有连续增益故障离散系统保性能可靠控制

针对不确定离散线性系统,采用连续增益故障模型,提出了考虑执行器故障的保性能可靠控制问题。通过对具有执行器故障不确定离散线性系统的分析,利用LMI分别给出了保性能标准控制器、保性能可靠控制器存在的充分条件及设计方法。根据凸优化理论．最优保性能标准控制器和最优保性能可靠控制器的设计方法转化为一个线性凸优化算法。在仿真数例中,不仅验证所提出方法的可行性;而且比较了最优保性能标准控制与最优保性能可靠控制。通过比较可以看出,当发生故障时,最优保性能标准系统将失去原有的性能和稳定性;最优保性能可靠系统仍将保持原有的性能。     

Dynamic Output Feedback Control of Switched Linear Systems

This paper is devoted to stability analysis and control design of switched linear systems in both continuous and discrete-time domains. A particular class of matrix inequalities, the so-called Lyapunov--Metzler inequalities, provides conditions for open-loop stability analysis and closed-loop switching control using state and output feedback. Switched linear systems are analyzed in a general framework by introducing a quadratic in the state cost determined from a series of impulse perturbations. Lower bounds on the cost associated with the optimal switching control strategy are derived from the determination of a feasible solution to the Hamilton--Jacobi--Bellman inequality. An upper bound on the optimal cost associated with a closed-loop stabilizing switching strategy is provided as well. The solution of the output feedback problem is based on the construction of a full-order linear switched filter whose state variable is used by the mechanism for the determination of the switching rule. Throughout, the theoretical results are illustrated by means of academic examples. A realistic practical application related to the optimal control of semiactive suspensions in road vehicles is reported.     

多变量线性系统解耦控制算法研究

由于耦合现象的存在使得多变量被控对象的控制和分析变得非常复杂,耦合严重时甚至使原来稳定的单回路系统变得发散,无法正常运行;针对这种现象,对多变量耦合被控对象的解耦问题进行了研究,阐述了多变量线性系统基于状态反馈和输入变换的解耦控制理论,详细推导了状态反馈矩阵和输入变换矩阵的构造方法和具体计算步骤,并就此问题给出了一个具有较高实用价值的MATLAB通用程序,仿真结果验证了该程序的有效性;为多变量耦合系统的进一步设计提供了条件.     

Adaptive Control of Piecewise Linear Systems with State Feedback for Output Tracking

A piecewise linear system consists of a set of linear time‐invariant (LTI) subsystems, with a switching sequence specifying an active subsystem at each time instant. This paper studies the adaptive control problem of single‐input, single‐output (SISO) piecewise linear systems. By employing the knowledge of the time instant indicator functions of system parameter switches, a new controller structure parametrization is proposed for the development of a stable adaptive control scheme with reduced modeling error in the estimation error signal used for parameter adaptive laws. This key feature is achieved by the new control scheme's ability to avoid a major parameter swapping term in the error model, with the help of indicator functions whose knowledge is available in many applications. A direct state feedback model reference adaptive control (MRAC) scheme is presented for such systems to achieve closed‐loop signal boundedness and small output tracking error in the mean square sense, under the usual slow system parameter switching condition. Simulation results on linearized NASA GTM models are presented to demonstrate the effectiveness of the proposed scheme.