基于模糊ANP的系统系的效能评估算法及其应用

针对系统系效能的综合评估问题,基于模糊ANP提出了一种新算法.考虑到效能之间的关联性,建立起分级式网络化效能评价指标系统系,实现了系统系(SoS)到子系统,再到系统功能之间的逐级映射,进而得到系统系效能评估的层次模型.采用改进模糊指数标度的网络分析法定量计算系统功能对系统系效能的权重,得到系统功能对系统系效能的贡献度.最后以微电网构成的电力系统为例验证分析,证明所提算法的有效性.     

基于ADRC的小型四旋翼姿态控制实现

设计了一个四旋翼飞行系统,提出了一种自抗扰控制方法,解决了该飞行系统的姿态控制问题.将显性互补滤波器与扩张状态观测器相结合,实现了对系统的状态与内外总扰动的实时估计,并在此基础上利用非线性误差反馈控制律对该扰动进行了补偿,消除了内外扰动对系统的影响.最后,分别采用PID与ADRC算法实现四旋翼的姿态控制,对比结果验证了所采用的自抗扰控制方法的有效性和优越性.     

SQCF系统的全局时滞混沌同步

考虑到在通信系统中接收端存在时滞问题,针对SQCF系统,以Lyapunov稳定性理论和矩阵论为基础,提出一种系统的全局混沌同步方案.通过选取适当的耦合参数,使误差系统全局渐近稳定,即使得响应系统在t+τ时刻的状态渐进地趋向于驱动系统在t时刻的状态.并用Mathematic软件给出了数值模拟,理论分析和数值仿真表明,该方法可以较快地实现混沌同步.对系统的第三变量z(t)进行扰动,数值仿真表明在扰动系统下仍能很好地保持同步,表明同步系统具有抗干扰性.     

基于观测器的一类模糊时滞系统的容错控制

针对一类带有传感器故障的模糊时滞系统,提出了一种实现对系统的状态和传感器故障估计的观测嚣设计方法.在此基础上,给出了模糊容错控制方法及保证模糊控制系统的渐近稳定充分条件.应用广义Lyapunov函数和线性矩阵不等式方法,证明了模糊闭环时滞系统的渐近稳定性.仿真结果进一步验证了所提出的方法和条件的有效性.     

基于自抗扰控制器的CNC雕刻机控制系统轮廓误差控制

针对CNC雕刻机控制系统因时变时延影响轮廓跟踪精度的问题,设计了基于自抗扰控制的单轴轨迹跟踪控制器和基于非线性PID(NLPID)的轮廓误差补偿控制器.首先,针对单轴轨迹跟踪控制,将时变时延引起的不确定性处理成系统总干扰的一部分,设计扩张状态观测器(ESO),对系统内外总干扰和系统状态进行实时估计,并设计误差补偿控制律,实现系统干扰的估计和补偿,得到良好的单轴轨迹跟踪控制性能.然后,根据轮廓误差估计值,设计基于NLPID的轮廓误差补偿控制器,对系统轮廓误差实时补偿,实现了良好的轮廓跟踪控制性能.最后,通过实验验证了所提方法的有效性.     

信息物理系统降阶观测器设计及传感器攻击检测

提出了一种适用于含有未知输入信号的信息物理系统降阶观测器设计方法及传感器攻击检测应用.首先,利用克罗内克积将信息物理系统描述为整体系统动态模型;然后考虑系统存在未知输入时,通过增加降阶观测器增益矩阵的约束条件,实现降阶的同时消除未知输入给系统带来的影响,再通过系统输出状态判断是否存在传感器攻击信号.最后,通过数值仿真,验证了所提降阶观测器对系统的状态估计及检测传感器攻击信号的能力,且对比仿真结果显示,所提降阶观测器性能优于全阶观测器.     

基于SVM极点分类的故障诊断与可靠控制

利用SVM分类技术,针对系统故障极点进行分类,利用网格搜寻法,实现对不同故障极点的分类进而实现对系统故障的检测和诊断,为了实现对系统极点变化的实时监测,给出了通过系统状态估计系统极点的新方法.在给出故障诊断的基础上,同时给出了针对相应故障的可靠控制器的设计.最后通过数例验证极点观测器对极点估计的准确性和故障诊断的准确性及可靠控制的有效性.     

基于扩张状态观测器的轮式移动机器人抗饱和自适应滑模轨迹跟踪控制

针对带有输入饱和约束的轮式移动机器人鲁棒轨迹跟踪问题,文章提出一种抗饱和自适应滑模控制方法.考虑到系统参数摄动和外部扰动等不确定因素对系统控制性能的影响,首先设计非线性扩张状态观测器来估计系统不确定因素,并基于估计值设计抗饱和自适应滑模控制器,消除系统的参数摄动、外部扰动和输入饱和约束对系统控制性能的影响.仿真对比结果验证了文章所提控制方法的优越性和有效性.     

多态防护系统可靠性及重要度分析

在装备防护系统中,系统中的所有部件都可能会受到攻击,为了降低攻击成功的概率,部件的防护层有多个状态,从完全失效状态到完好状态,部件的防护功能依次增加。本文分析了部件防护层的状态变化规律,研究了当部件受到攻击存活和故障时的平均性能变化机理。然后基于系统结构函数,分别给出了防护层的Birnbaum重要度和综合重要度,分析了当部件防护层的状态发生变化时,系统性能的变化规律和特性;并考虑部件防护层的状态转移率,分析了在多种状态变化情况下的防护层提升对系统性能的影响。最后针对某直升机的航空动力装置系统,分析了不同部件防护层对系统性能的影响,并比较了Birnbaum重要度和综合重要度的不同,验证了提出方法的正确性和有效性。     

一种新的非线性系统传感器漂移性能退化实时监测方法

随着传感器使用时间的增加,其测量值会发生漂移,且漂移程度会随时间的增加而增大.针对非线性系统中的传感器漂移性退化现象,基于改进的粒子滤波算法,提出了传感器漂移性能退化实时监测方法.该方法通过实时估计漂移量来实现对系统状态的估计,能够检测并跟踪动态系统中传感器性能退化过程,为系统安全运行提供保障.基于三容水箱系统的仿真验证了该方法的有效性.     

Minimax control of systems with uncertain state measurements

A system is controlled with the aid of uncertain state measurements, the errors of which are known to lie within a given, compact set. Control of the system incurs a cost of which it is desired that the largest value consistent with the measurements obtained be minimized. Two different measurement régimes are considered. In the first, measurements are obtained throughout the history of the process and, in the second, only an initial state measurement is obtained. Under certain circumstances, it is shown that the optimization problems for the two régimes are equivalent. The general solution of the problem for the second régime is given for the case when the dynamics are linear, and the cost function quadratic.The research activity of this author was supported in part by ONR.     

受扰不确定混沌系统的降阶修正函数投影同步

研究了具有不同阶数的受扰不确定混沌系统的降阶修正函数投影同步问题.基于Lyapunov稳定性理论和自适应控制方法,设计了统一的非线性状态反馈控制器和参数更新规则,使得混沌响应系统按照相应的函数尺度因子矩阵和混沌驱动系统的部分状态变量实现同步.方法考虑了实际系统中的模型不确定性和外界扰动,具有较强的实用性和鲁棒性.数值仿真证明了控制方法的有效性.     

Analysis and design of switched normal systems

In this paper, we study the stability property for a class of switched linear systems whose subsystems are normal. The subsystems can be continuous-time or discrete-time ones. We show that when all the continuous-time subsystems are Hurwitz stable and all the discrete-time subsystems are Schur stable, a common quadratic Lyapunov function exists for the subsystems and thus the switched system is exponentially stable under arbitrary switching. We show that when unstable subsystems are involved, for a desired decay rate of the system, if the activation time ratio between stable subsystems and unstable ones is less than a certain value (calculated using the decay rate), then the switched system is exponentially stable with the desired decay rate.     

Analysis and design of switched normal systems

In this paper, we study the stability property for a class of switched linear systems whose subsystems are normal. The subsystems can be continuous-time or discrete-time ones. We show that when all the continuous-time subsystems are Hurwitz stable and all the discrete-time subsystems are Schur stable, a common quadratic Lyapunov function exists for the subsystems and thus the switched system is exponentially stable under arbitrary switching. We show that when unstable subsystems are involved, for a desired decay rate of the system, if the activation time ratio between stable subsystems and unstable ones is less than a certain value (calculated using the decay rate), then the switched system is exponentially stable with the desired decay rate.     

Algorithm of the resolving of a boundary-value problem for a nonlinear controlled system and its numerical modeling

An algorithm to construct a differentiable control function guaranteeing the transfer nonlinear stationary systems of ordinary differential equations from the initial state to a given final state of the phase space such that restrictions for the control are satisfied is proposed. The proposed algorithm is convenient for numerical implementation and is applicable to a broad class of systems. A sufficient condition of the existence of a desired transfer function is constructed. A certain practical problem is considered and simulated numerically by means of the presented method.     

Poisson冲击下的$k/n(G)$系统的可靠性分析

本文研究了一类Poisson冲击下的$k/n(G)$系统(即$k$-out-of-$n$: $G$系统). 假定冲击的到达数形成一个参数为$\lambda$的Poisson过程, 且冲击的量服从某一分布. 当每次冲击到达时, 对系统中工作的部件独立地产生影响. 进而假定每一部件以一定的概率故障, 概率值是冲击量的函数. 且各次冲击独立地对系统造成损失, 直到工作部件数少于$k$系统故障为止. 在这些假定下, 我们获得了系统的可靠度函数和系统的平均工作时间. 进一步, 假定系统是可修的, 系统中有一个维修工, 并根据``先坏先修’’的维修规则对故障部件进行维修. 在维修时间服从指数分布的假设下, 系统状态转移服从Markov过程. 对该系统我们建立了状态转移方程, 并求得了系统可用度、稳态下的平均工作时间、平均停工时间和系统失效频率等可靠性指标. 最后, 我们还给出了一个简单例子来演示讨论的模型.     

Controlling chaos in space-clamped FitzHugh–Nagumo neuron by adaptive passive method

The space-clamped FitzHugh–Nagumo (SCFHN) neuron exhibits complex chaotic firing when the amplitude of the external current falls into a certain area. To control the undesirable chaos in SCFHN neuron, a passive control law is presented in this paper, which transforms the chaotic SCFHN neuron into an equivalent passive system. It is proved that the equivalent system can be asymptotically stabilized at any desired fixed state, namely, chaos in SCFHN neuron can be controlled. Moreover, to eliminate the influence of undeterministic parameters, an adaptive law is introduced into the designed controller. Computer simulation results show that the proposed controller is very effective and robust against the uncertainty in systemic parameters.     

A general result in stochastic optimal control of nonlinear discrete-time systems with quadratic performance criteria

It is known that the optimal controller for a linear dynamic system disturbed by additive, independently distributed in time, not necessarily Gaussian, noise is a linear function of the state variables if the performance criterion is the expected value of a quadratic form. This result is known to hold also when the noise is Gaussian and is multiplied by a linear function of the state and/or control variables.In this paper it is proved that the optimal controller for a discrete-time linear dynamic system with quadratic performance criterion is a linear function of the state variables when the additive random vector is a nonlinear function of the state and/or control variables and not necessarily Gaussian noise which is independently distributed in time, provided only that the mean value of the random vector is zero (there is no loss of generality in assuming this) and the covariance matrix of the random vector is a quadratic function of the state and/or control variables. The above-mentioned known results emerge as special cases and certain nonlinear other special cases are exhibited.     

Adjoint-Based Optimal Boundary Control of a Stefan Problem System Fully Coupled with Navier-Stokes Equations

Free boundary and moving boundary problems, that can be used to model crystal growth or the solidification and melting of pure materials, receive growing attention in science and technology. The optimal control of these problems appear even more interesting since certain desired shapes of the boundaries improve, e.g., the material quality in the case of crystal growth. We consider the so called two-phase Stefan problem that models a solid and a liquid phase separated by a moving interface. In the work presented, we take a sharp interface model approach and define a quadratic tracking-type cost functional that penalizes the deviation of the interface from the desired state at a final time as well as the control costs. Following the “optimize-then-discretize” paradigm, we formulate a first order optimality system using the formal Lagrange approach and derive the adjoint PDE system that provides the needed gradient of the cost functional. By means of an example setup of a container with an in- and outflow of water and a cooling unit at the bottom, we illustrate how the derived formulations can be used to achieve a desired interface between the solid and the fluid phase by controlling the flow at the inlet. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On Optimization of the Full Radiative Heat Transfer System

Solving the full radiative heat transfer equation, moderately discretized in space, time, frequency and direction, results in a tremendously huge system of equations. A common approach to avoid this problem is to use moment methods neglecting the directional dependence on radiation. Our approach, however, is to solve the full radiative heat transfer system with all dependencies and to optimize the heat distribution and the radiative flux, respectively, for a desired temperature function or desired radiative flux function. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)