n比特随机量子系统实时状态估计及其反馈控制

研究了$n $比特随机量子系统实时状态估计及其反馈控制的问题. 对于连续弱测量(Continuous weak measurement, CWM)过程存在高斯噪声的情况, 基于在线交替方向乘子法(Online alternating direction multiplier method, OADM)推导出一种适用于$n $比特随机量子系统的实时量子状态估计算法, 即QSE-OADM (Quantum state estimation based on OADM). 运用李雅普诺夫方法设计控制律, 实现基于实时量子状态估计的反馈控制, 并证明所提控制律的收敛性. 以2比特随机量子系统为例进行数值仿真实验, 通过与基于QST-OADM (Quantum state tomography based on OADM)算法和OPG-ADMM (Online proximal gradient-based alternating direction method of multipliers)算法的量子反馈控制方案的性能对比, 验证了所提控制方案的优越性.     

基于李雅普诺夫量子系统控制方法的状态调控

从多方面对基于李雅普诺夫的量子系统控制方法进行了系统深入地研究, 包括该方法与最优控制的关系; 李雅普诺夫函数与性能指标之间的关系; 几种常用李雅普诺夫函数下的控制所能解决的问题, 适用范围和所存在的问题等. 在此基础上, 结合量子系统本身所具有的特点, 分别针对本征态, 叠加态和混合态的制备与调控目标, 总结出多种不同控制问题的改进方案. 对不同改进方案的设计思想, 所能解决的问题, 物理意义及其适用范围等进行剖析, 系统化了一套基于李雅普诺夫稳定性理论对量子系统进行状态调控的设计方法.     

未知环境下基于虚拟角速度跟踪的避障策略EI北大核心CSCD

当智能体自主执行任务时,局部障碍物可测的未知环境增加了局部极值和执行器饱和发生的概率.对此,本文提出了虚拟角速度跟踪的避障策略.首先,基于简易障碍物的几何模型构造虚拟的避障引导角,并利用李雅普诺夫方法设计角速度控制律,通过受限制的虚拟角速度跟踪来实现避障控制.然后,引入方位因子改进距离型权值分配器,强化轨迹附近障碍物的影响以降低局部极值发生的概率.最后,对于不完全可测的复杂障碍物,根据历史探测信息建立以边界点为中心的简易障碍物模型.仿真结果表明,该策略能够避让低速动态障碍物及U型复杂障碍物,并且可实现抗饱和控制.     

DoS攻击下随机系统的攻击参数依赖型观测器与控制器协同设计EI北大核心CSCD

本文研究了拒绝服务攻击下网络随机控制系统的攻击参数依赖型观测器与控制器协同设计问题.首先,将拒绝服务(DoS)攻击建模为周期脉宽调制干扰信号,并构造了Luenberger观测器来估计不可测的系统状态.其次,设计了基于观测器的控制器,提出一种新的切换随机系统模型.然后,引入DoS攻击参数依赖型随机时变李雅普诺夫函数分析切换随机系统.给出了切换随机系统均方指数稳定的判据,并使闭环系统具有L_(2)增益性能水平.同时通过应用矩阵不等式技术,给出了攻击参数依赖型观测器与控制器的协同设计方案.最后,以一种飞行器系统为例,验证了该方案的有效性.     

基于状态距离的量子控制策略

基于Bures距离,选择一个表征量子系统期望态和实际态间距离的Lyapunov函数.考虑到初始态与期望态分别正交和不正交的情况,提出一类带有状态反馈的控制策略,它可以保证闭环控制系统的稳定性.特别详细地分析、推导和证明了系统的渐进稳定性.最后,在一个自旋1/2粒子系统上进行了仿真实验,分析了不同参数情况下系统的状态演化时间和控制值间的关系.研究结果对于量子系统的控制具有一般理论意义.     

不确定奇异周期系统的鲁棒容错H_∞控制北大核心CSCD

针对一类具有外部扰动输入的不确定奇异周期系统,研究了该类系统的鲁棒容错H∞控制的问题,其中不确定性存在于系统的状态矩阵和输入矩阵当中,且满足范数有界条件。利用线性矩阵不等式(LMI)和李雅普诺夫不等式的分析方法提出了不确定奇异周期系统的鲁棒二次稳定和鲁棒二次可镇定且具有H∞性能指标的概念,得到了该类系统鲁棒容错H∞控制的充分和必要条件,并给出了系统状态反馈鲁棒容错H∞控制器的设计方法,所设计的H∞控制器既保证了闭环系统对故障发生时的鲁棒性,又能保证系统满足一定的H∞性能γ。研究成果是不确定奇异定常系统鲁棒容错H∞控制结论向不确定奇异周期系统的推广,因而具有较大的理论意义。最后,文章给出的数值算例证明了结论的有效性。     

基于纯态的量子通信系统模型

量子通信与量子计算已经引起人们极大的关注.对于量子态如何用于信息处理的问题,提出了量子通信的两种基本模型:量子直接通信模型与量子隐形传态通信模型.在量子直接通信模型中,用模块化的方法将量子通信全过程分为量子信源编译码,量子信道编译码,量子信道与量子噪声模块,并详细阐述了各个模块的功能与用途.在量子隐形传态通信模型中,利用量子隐形传态特性,通过将待传粒子与纠缠对的联合测量模块化为量子调制部分,给出了基于隐形传态的量子通信一般模型.量子通信在安全性及效率方面具有经典通信无法比拟的优势.     

李雅普诺夫函数优化:正交矩阵构造方案EI北大核心CSCD

本文研究了李雅普诺夫函数的优化问题.提出了一种正交矩阵构造方案,用于求解黎卡提不等式中的最优李雅普诺夫函数.通过分析系统H_(∞)范数的几何特征,本文将黎卡提不等式转换为近似等式,进而给出了最优李雅普诺夫函数的存在条件.基于所给最优李雅普诺夫函数存在条件,所提正交矩阵构造方案利用旋转变换,将非线性方程组的求解问题转换为幅值和角度的线性优化问题,进而实现李雅普诺夫函数参数的优化.研究结果弥补了目前的研究无法求解最优李雅普诺夫函数的不足,对系统性能分析和非保守控制的设计具有建设性.算例验证了所提正交矩阵构造方案的有效性.     

随机激励下非线性水轮机系统的控制设计

针对一类随机非线性哈密顿系统提出了一种全新的反馈跟踪控制方法.该控制策略可以准确地控制系统输出的概率密度分布特性.闭环系统的稳定性也通过李雅普诺夫函数法得到严格的数学证明.最后,以随机非线性水轮机系统为例,详细演示了控制设计过程及其有效性.仿真结果表明,新的反馈控制策略可以使水轮机系统的输出满足预先指定的平稳概率密度函数.     

基于观测器的切换模糊时滞系统的反馈控制

针对状态不可测的切换模糊时滞系统, 根据平行分布补偿算法(PDC), 设计了切换模糊观测器和反馈控制器, 应用共同Lyapunov函数方法使观测误差系统在任意切换下渐近稳定, 应用多Lyapunov函数方法, 使系统状态在设计切换律下渐近稳定, 并给出了时滞相关的切换模糊系统渐近稳定的矩阵不等式条件. 仿真结果表明结论的有效性.     

量子系统动态函数的跟踪控制

以随时间变化的二次函数为目标函数,对采用薛定谔方程的量子系统进行轨迹跟踪研究。根据Lyapunov稳定性定理,选择误差的平方作为Lyapunov函数设计控制律,实现系统从任意初始状态到目标函数的跟踪。在Matlab环境下对不同初始状态进行了系统仿真及性能对比研究,分析了系统初始值以及控制中观测量对跟踪性能的影响,验证了控制律在跟踪目标函数上的优越性。     

Stabilisation of discrete 2D time switching systems by state feedback control

This article deals with sufficient conditions of asymptotic stability for discrete two-dimensional (2D) time switching systems represented by a model of Roesser type with state feedback control. This class of systems can correspond to 2D state space or 2D time space switching systems. This work is based on common and multiple Lyapunov functions. The results are presented in LMI form. Two examples are given to illustrate the results.     

An implicit Lyapunov control for finite‐dimensional closed quantum systems

In this paper, the state convergence problem for closed quantum systems is investigated. We consider two degenerate cases, where the internal Hamiltonian of the system is not strongly regular or the linearized system around the target state is not controllable. Both the cases are closely related to practical systems such as one‐dimensional oscillators and coupled two spin systems. An implicit Lyapunov‐based control strategy is adopted for the convergence analysis. In particular, two kinds of Lyapunov functions are defined by implicit functions and their existences are guaranteed by a fixed point theorem. The convergence analysis is investigated by the LaSalle invariance principle for both cases. Moreover, the two Lyapunov functions are unified in a general form, and the characterization of the largest invariant set is presented. Finally, simulation studies are included to show the effectiveness and advantage of the proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.     

Adaptive tracking control for a class of random pure‐feedback nonlinear systems with Markovian switching

This note studies the tracking control problem for a class of random pure‐feedback nonlinear systems with Markovian switching and unknown parameters. An adaptive tracking controller is constructed by introducing an auxiliary integrator subsystem and using the improved backstepping method such that the closed‐loop system has a unique solution that is globally bounded in probability. Meanwhile, the tracking error can converge to an arbitrarily small neighborhood of zero via the parameter regulation technique. The efficiency of the tracking controller designed in this paper is demonstrated by simulation examples.     

Stabilization of stochastic coupled systems with Markovian switching via feedback control based on discrete‐time state observations

This study investigates the stabilization issue of stochastic coupled systems with Markovian switching via feedback control. A state feedback controller based on the discrete‐time observations is applied for the stabilization purpose. By making use of the graph theory and the Lyapunov method, we establish both Lyapunov‐ and coefficient‐type sufficient criteria to guarantee the stabilization in the sense of stability, and then, we further develop the mean‐square asymptotical stability. In particular, the upper bound of the duration between 2 consecutive state observations is well formulated. Applications to a concrete stabilization problem of stochastic coupled oscillators with Markovian switching and some numerical analyses are presented to illustrate and to demonstrate the easy verifiability, effectivity, and efficiency of our theoretical findings.     

Implicit Lyapunov‐based control strategy for closed quantum systems with dipole and polarizability coupling

In this paper, the state transfer of finite dimensional closed quantum systems with dipole and polarizability coupling in non‐ideal cases is investigated. Two kinds of non‐ideal systems are considered, where the internal Hamiltonian of the system is not strongly regular and not all the eigenvectors of the internal Hamiltonian are directly coupled with the target state. Such systems often exist in practical quantum systems such as the one‐dimensional oscillator and coupled two‐spin system. An implicit Lyapunov‐based control strategy is proposed here with convergence analysis for quantum systems modeled by finite dimensional bilinear Schrödinger equations. Specifically, two kinds of Lyapunov functions are defined via implicit functions, and their existences are guaranteed with the help of a fixed point theorem. Then, the local convergence analysis is investigated with the explicit characterization of the largest invariant set by LaSalle invariance principle. Finally, the performance of the feedback design is illustrated by numerical simulations. Copyright © 2017 John Wiley & Sons, Ltd.     

量子力学系统的输出反馈控制

研究量子系统输出反馈控制问题建模以及控制律设计问题.首先讨论了量子力学VonNeumann测量原理与连续测量模型的一致性;然后在连续测量模型的基础上总结了已有量子反馈模型的结果,归纳出量子输出反馈控制系统模型;最后针对单比特振幅退相干抑制问题,利用线性直接输出反馈控制设计反馈控制律,指出利用最优控制的方法设计线性输出反馈控制的比例系数,可以得到较好的结果.     

Fault tolerance analysis for stochastic systems using switching diffusion processes

This article models a class of stochastic systems with faults by switching diffusion processes (SDP), and analyses the fault tolerability of such stochastic systems in the sense of input-to-state stability of overall SDP. The fault tolerability relies on the trade-off among the fault occurrence transition rate, the frequency of switching, and the decreasing rate of Lyapunov functions along the solution of the system. Our results show that it may not be necessary to design the fault tolerant controller even though the stochastic system is not separately stable in the healthy and faulty situations, the stability of the overall system process is still guaranteed under some conditions. The proposed tools are illustrated through an example of a fault-prone manufacturing system.