线性广义系统的无源控制

考察了线性广义系统的无源性控制问题．一方面，利用微分几何方法，给出了广义系统无源的充分必要条件;另一方面，将存储函数具体化，利用线性矩阵不等式，推出了广义系统无源的充分条件．最后，基于这两个方面得到存在状态反馈且使闭环系统无源和严格无源的条件．     

不确定随机系统LQG对偶控制

针对不确定性模型为多胞型的随机系统进行了对偶控制的研究．首先，假定多胞型不确定参数存在于状态空间模型的系统矩阵、输入矩阵和量测矩阵中．其次，将此不确定性模型通过不确定参数的后验概率加权，得到其增广系统．然后，使用动态规划得到增广系统的次优控制律．最后，通过仿真验证了本文方法的可行性和有效性．     

线性奇异系统的H_∞控制问题:状态反馈情形

讨论了线性奇异系统的状态反馈H∞ 控制问题 ,阐述了其和一个正常状态空间线性系统的状态反馈H∞控制问题的等价性 ;利用线性矩阵不等式 (LMI)的方法 ,给出了一个使闭环系统无脉冲模 ,内稳定 ,且满足H∞ 性能指标的状态反馈控制器存在的充分必要条件及控制器的一族解     

线性奇异系统的H∞控制问题: 状态反馈情形

讨论了线性奇异系统的状态反馈H∞控制问题,阐述了一个正常状态空间线性系统的状态反馈H∞控制问题的等价性;利用线性矩阵不等式（LMI）的方法,给出了一个使闭环系统无脉冲模,内稳定,且满足H∞性能指标的状态反馈控制器存在的充分必要条件及控制器的一族解。     

一类切换时滞奇异系统的状态反馈H∞控制*

研究一类由任意有限多个时滞奇异子系统组成的切换系统的状态反馈H∞控制问题。利用Lyapunov函数方法和凸组合技术,给出由矩阵不等式表示的控制器存在的充分条件,并设计了相应的子控制器和切换规则。采用变量替代方法,将该矩阵不等式转换为一组线性矩阵不等式(LMIs),最后给出一个求解状态反馈控制器增益矩阵的仿真算例。研究结果表明,通过切换,闭环系统在整个状态空间上的每个点都满足H∞性能,并不要求每个子系统在整个状态空间上都满足H∞性能,甚至也不要求其渐进稳定。     

不确定切换时滞奇异系统的鲁棒H_∞控制

研究一类由任意有限多个具有参数不确定性和状态时滞的奇异子系统组成的切换系统的状态反馈鲁棒H∞控制问题。利用Lyapunov函数方法和凸组合技术,给出由矩阵不等式表示的控制器存在的充分条件,并设计了相应的子控制器和切换规则。采用变量替代方法,将该矩阵不等式转化为一组线性矩阵不等式(LMIs)。最后给出电力系统中一个求解状态反馈控制器增益矩阵的仿真算例证明结论的有效性。研究结果表明,通过切换,闭环系统在整个状态空间上的每个点都满足鲁棒H∞性能,而并不要求每个子系统在整个状态空间上都满足鲁棒H∞性能,甚至也不要求其渐近稳定。     

状态空间分析

六十年代发展起来的所谓现代控制理论是建立在状态空间概念上的。但在经典力学、量子力学、常微分方程等领域,早就应用了状态空间的概念。以后,象四十年代自动控制领域建立的稳定性理论,五十年代发展的关于设计线性系统和非线性系统的最优化以及线性系统的可控性和可观测性问题,都引入了状态空间的概念。     

不确定离散切换系统具有极点约束的保性能控制

对一类含有范数有界不确定性的离散切换系统和一个二次型性能指标，研究其具有闭环极点约束的鲁棒状态反馈保性能控制问题．利用二次Lyapunov函数方法和线性矩阵不等式技术，给出了鲁棒保性能控制器存在的一个充分条件，在所构造切换规则下，闭环系统二次D稳定，且满足给定的性能指标．在此基础上，将次优保性能控制器设计问题转化为一组线性矩阵不等式约束下的凸优化问题．数值例子说明了所提方法的有效性．     

时滞不确定线性互联大系统分散鲁棒H_∞控制

讨论了含多重控制和状态时变时滞的不确定线性互联大系统的分散鲁棒 H∞ 控制问题 ,给出分散状态反馈问题有解的充分条件 ,并将其转化为一个线性矩阵不等式的求解     

空间几何对象相对位置的新安全判定方法

针对空间几何对象相对位置判定问题提出一种新的解决方案,也就是运用矩阵秩的概念和一般矩阵求和的安全两方计算协议秘密判定空间几何对象相对位置问题.关于此问题,之前罗永龙教授设计了对应成比例判定协议,而文中则利用矩阵秩的概念和一般矩阵求和的安全两方计算协议设计了一些基础的空间几何对象相对位置安全判定协议.运用此协议解决了空间中的平面与平面位置关系问题、平面与直线位置关系问题和直线与直线位置关系问题.提出的新安全判定方法不久解决了空间几何对象相对位置判定问题,也将在其他安全多方计算问题中起到重要作用.     

Optimal control of two-level quantum systems

We study the manipulation of two-level quantum systems. This research is motivated by the design of quantum mechanical logic gates which perform prescribed logic operations on a two-level quantum system, a quantum bit. We consider the problem of driving the evolution operator to a desired state, while minimizing an energy-type cost. Mathematically, this problem translates into an optimal control problem for systems varying on the Lie group of special unitary matrices of dimension two, with cost that is quadratic in the control. We develop a comprehensive theory of optimal control for two-level quantum systems. This includes, in particular, a classification of normal and abnormal extremals and a proof of regularity of the optimal control functions. The impact of the results of the paper on nuclear magnetic resonance experiments and quantum computation is discussed     

State controllability and optimal regulator control of time-delayed systems

An important recent advance in the solution of the optimal regulator control problem for time-delayed systems is extended here to multivariable systems and to systems which exhibit multiple time delays. The state equations are partitioned into discrete and continuous portions through a state transformation such that the solution of the optimal regulator problem reduces to finding a steady-state controller gain based on both a discrete and continuous Riccati matrix. The discrete Ricatti matrix is found independently of the continuous solution due to the partitioning of the state equations, and it is not necessary to solve the system of partial differential Riccati equations which arise in the traditional solution of the linear quadratic regulator (LQR) problem for time-delayed systems. In addition, through this state transformation it becomes possible to extend the standard state controllability tests to time-delayed systems. It is shown that the controllability of the transformed state space is necessary for a feasible solution to the optimal regulator problem for time-delayed systems. This is an important test to determine the practicality of various time-delayed system realizations. Numerical examples illustrate the application of the technique to systems exhibiting multiple time delays, multivariable systems and time-series models. It is shown that the classic Wood-Berry distillation model realization does not possess state controllability properties which explains why this system has been historically difficult to control using feedback techniques.     

Feedback control of quantum state reduction

Feedback control of quantum mechanical systems must take into account the probabilistic nature of quantum measurement. We formulate quantum feedback control as a problem of stochastic nonlinear control by considering separately a quantum filtering problem and a state feedback control problem for the filter. We explore the use of stochastic Lyapunov techniques for the design of feedback controllers for quantum spin systems and demonstrate the possibility of stabilizing one outcome of a quantum measurement with unit probability.     

Termination of nondeterministic quantum programs

We define a language-independent model of nondeterministic quantum programs in which a quantum program consists of a finite set of quantum processes. These processes are represented by quantum Markov chains over the common state space, which formalize the quantum mechanical behaviors of the machine. An execution of a nondeterministic quantum program is modeled by a sequence of actions of individual processes, and at each step of an execution a process is chosen nondeterministically to perform the next action. This execution model formalize the users’ behavior of calling the processes in the classical world. Applying the model to a quantum walk as an instance of physically realizable systems, we describe an execution step by step. A characterization of reachable space and a characterization of diverging states of a nondeterministic quantum program are presented. We establish a zero-one law for termination probability of the states in the reachable space. A combination of these results leads to a necessary and sufficient condition for termination of nondeterministic quantum programs. Based on this condition, an algorithm is found for checking termination of nondeterministic quantum programs within a fixed finite-dimensional state space.     

输入多采样率数字控制系统的同时极点配置

在利用提升(lifting)技术所构造出来的多采样率数字控制系统的线性时不变状态空间模型的基础上, 讨论l个被控对象通过输入多采样率数字控制系统的同时极点配置问题. 分别引入了解决这一问题的状态空间方法和多项式矩阵插值方法. 通过适当的变换, 将同时极点配置问题归结为一系列线性方程组的求解问题. 指出, 当系统的输入采样率满足一定条件时, 可以利用输入多采样率的输出静态反馈控制系统, 实现对l个被控对象的同时极点配置.     

开放环境下多比特量子计算机的相干控制模型

研究了开放环境下多比特量子计算系统的相干控制建模问题.基于开放量子系统的数学模型,选取适当的矩阵基将描述多比特量子计算机的复矩阵动态控制模型转化为实向量空间上的控制模型,并给出计算相应的结构系数的方法.这些工作提供了进一步研究控制律设计的基础.     

Robust control of a class of under-actuated mechanical systems with model uncertainty

Robust control of under-actuated mechanical systems (UMSs) with model uncertainty is still a challenging problem. For UMSs, the model parametric uncertainties make it difficult to precisely calculate the isolated equilibrium point corresponding to a fixed input. Without an accurate destination state, many set-point control methods cannot eliminate the positioning errors. An improved sliding mode control (ISMC) method is proposed to solve the robust control problem for a class of UMSs with model uncertainty and input disturbance. A balance variable is introduced in the sliding surface design to compensate for the disturbance caused by the inaccurate destination state, and the ISMC method is proposed to make the system state reach the sliding surface in finite time. Linear matrix inequality approach and particle swarm optimisation algorithm are applied to design the sliding mode surface parameters. The simulation results on an UMS are presented to show the effectiveness of the proposed scheme.     

Exact model-matching control of three-dimensional systems using state and output feedback

For a general state space model of three-dimensional (3-D) systems, the exact model-matching control problem via state and output feedback ia considered. A frequency domain approach is employed in which the 3-D prototype system (model) is given in transfer function matrix of the form G _m(p, w, z). The approach is based on equating the closed-loop transfer matrix function G _c(p, w, z) to G _m(p, w, z) and solving for the required feedback matrix gains through an application of Kronecker matrix product concept. We start with the static feedback case, and then treat the dynamic feedback problem for the important case of proportional plus integral plus derivative (PID) control. The approach leads to a set of linear algebraic equations, which involve the necessary and sufficient conditions for the exact model matching problem to have a solution. Two simple, but non-trivial examples, are computed.     

A multiple-kernel LSSVR method for separable nonlinear system identification

In some nonlinear dynamic systems, the state variables function usually can be separated from the control variables function, which brings much trouble to the identification of such systems. To well solve this problem, an improved least squares support vector regression （LSSVR） model with multiple-kernel is proposed and the model is applied to the nonlinear separable system identification. This method utilizes the excellent nonlinear mapping ability of Morlet wavelet kernel function and combines the state and control variables information into a kernel matrix. Using the composite wavelet kernel, the LSSVR includes two nonlinear functions, whose variables are the state variables and the control ones respectively, in this way, the regression function can gain better nonlinear mapping ability, and it can simulate almost any curve in quadratic continuous integral space. Then, they are used to identify the two functions in the separable nonlinear dynamic system. Simulation results show that the multiple-kernel LSSVR method can greatly improve the identification accuracy than the single kernel method, and the Morlet wavelet kernel is more efficient than the other kernels.     

两能级封闭量子系统任意量子态的最优制备

在分析单量子位的Bloch球面表示的基础上，结合量子门实现量子态幺正演化的量子态调控机制，提出一种针对两能级封闭量子系统任意量子态的最优制备策略．该策略首先建立两能级量子系统及其控制场的模型；然后借助李群李代数．由经典最优控制的思想和约化动力学来获得最优控制，从而达到两能级封闭量子系统任意量子态的最优制备．理论分析与仿真实验表明了该策略的优越性．