基于高频增益矩阵分解的多变量系统自适应控制

基于高频增益矩阵因子分解和Backstepping设计方法,对多变量MRAC系统设计出一种新的自适应控制器,改变了已有的研究中关于高频增益矩阵的假定条件.该控制器能保证系统的全局稳定性和跟踪误差趋于零.仿真效果也证明了所提算法的实用性.     

一类参数不确定性混沌系统的T-S模糊控制

针对一类参数不确定性混沌系统,首次提出利用区间矩阵理论描述其不确定性,进而用T-S模糊模型对其进行精确描述的新方法.在此T-S模糊模型的基础上,给出一种基于并行分布补偿(PDC)技术的状态反馈控制器设计方法,并用Lyapunov稳定性理论证明了闭环系统的鲁棒稳定性.该方法充分考虑了模糊子系统之间的相互作用.状态反馈控制器增益矩阵可以通过求解一组线性矩阵不等式(LMIs)获得.仿真结果验证了所提方法的有效性.     

数组微分方程组广义同步系统理论研究

实现数组微分动力系统广义同步是进行图像保密通信的前提。在引入映射在矩阵域中下降这一新定义的基础上,提出了一个实现数组微分动力系统广义同步的新定理,给出了广义系统初始条件选取的方法,据此可构造通过线性变换达到广义同步的数组微分动力系统,即理论上可以构造出图像保密通信的发射系统和接收系统。通过引入实例,说明该定理构造一个广义同步的数组微分动力系统。数值模拟结果结果表明,运用定理构造成的数组广义同步系统实现了混沌广义同步。     

Efficient coding schemes with power allocation using space-time-frequency spreading

1 .INTRODUCTIONOver the last few years , space-ti me coding[1]hasreceived a lot of attention among communicationand information theory community , which in-tegrates the technique of antenna array spatial di-versity and channel coding,and can effectivelyi m-prove capacity gains and spectral efficiency . Mostwork on space-ti me coding has focused on the nar-row-band flat fading channels . However , non-flatfading channels such as frequency selective mul-tipath fading channels are the typical…     

Robust adaptive neural network control with supervisory controller

The problem of direct adaptive neural network control for a class of uncertain nonlinear systems with unknown constant control gain is studied in this paper. Based on the supervisory control strategy and the approximation capability of multilayer neural networks (MNNs), a novel design scheme of direct adaptive neural network controller is proposed.The adaptive law of the adjustable parameter vector and the matrix of weights in the neural networks and the gain of sliding mode control term to adaptively compensate for the residual and the approximation error of MNNs is determined by using a Lyapunov method. The approach does not require the optimal approximation error to be square-integrable or the supremum of the optimal approximation error to be known. By theoretical analysis, the closed-loop control system is proven to be globally stable in the sense that all signals involved are bounded, with tracking error converging to zero.Simulation results demonstrate the effectiveness of the approach.     

时间滞后系统鲁棒控制方法及在飞控中的应用

给出了一种时间滞后系统的鲁棒控制方法。通过对系统鲁棒稳定性条件不等式的等价变形，得到了该不等式可解的条件并且大大简化了不等式；从而得到了包含复极点的时间滞后系统的鲁棒稳定性判据。针对系统具有多个时间滞后问题，运用系统单个滞后的鲁棒稳定性不等式判据，给出了包含复极点的简明鲁棒稳定性判别式。该方法接近于普通的状态反馈设计，便于工程实现。飞行器控制设计的仿真计算结果表明，采用新方法可以得到满意的设计结果。     

Combined indirect and direct method for adaptive fuzzy output feedback control of nonlinear system

A novel control method for a general class of nonlinear systems using fuzzy logic systems (FLSs) is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.     

正弦型非线性调频键控及性能分析

以正弦型非线性调频信号为载波样本,提出一种非单频波带通调制方法--正弦型非线性调频键控（sine non-linear chirp keying, SNCK）。通过调整时间带宽积和频率变化曲线频率等参数,SNCK可实现满足不同信道环境和服务质量需求的无线通信。同时,由于采用非单频波作为载波样本,SNCK具有较好的多普勒频移抑制能力。构建SNCK的数学模型,分析已调信号正交化设计方法、频域特征及信道适应能力等性能。理论分析和实验结果表明：相较于甚小线性调频键控,SNCK具有相近的高白噪声抑制能力和频域能量集中度;相较于最小频移键控,SNCK具有更强的多普勒频移抑制能力。SNCK可作为通信终端高速率运动场景下的变速率无线通信系统的带通调制方案。     

基于Haar小波运算矩阵的分数阶系统辨识方法

分数阶微积分因为其阶数可以是任意数，因此能够更加准确的描述动态系统。虽然分数阶系统受到了越来越多的重视，可是，如何建立分数阶系统目前仍处于积极探究阶段。考虑到分数阶微分的非局部性，利用小波运算矩阵为工具，给出了一种分数阶系统的辨识方法。其好处在于能够利用小波的多分辨特性对激励信号和响应信号进行数据压缩，从而降低运算矩阵的维数，可解决因矩阵维数过大导致内存溢出的问题。     

Receding horizon H∞ control for discrete-time Markovian jump linear systems

Receding horizon H∞ control scheme which can deal with both the H∞ disturbance attenuation and mean square stability is proposed for a class of discrete-time Markovian jump linear systems when minimizing a given quadratic performance criteria. First, a control law is established for jump systems based on pontryagin’s minimum principle and it can be constructed through numerical solution of iterative equations. The aim of this control strategy is to obtain an optimal control which can minimize the cost function under the worst disturbance at every sampling time. Due to the difficulty of the assurance of stability, then the above mentioned approach is improved by determining terminal weighting matrix which satisfies cost monotonicity condition. The control move which is calculated by using this type of terminal weighting matrix as boundary condition naturally guarantees the mean square stability of the closed-loop system. A sufficient condition for the existence of the terminal weighting matrix is presented in linear matrix inequality (LMI) form which can be solved efficiently by available software toolbox. Finally, a numerical example is given to illustrate the feasibility and effectiveness of the proposed method.     

宽带MIMO系统低复杂度压扩变换

针对循环前缀（cyclic prefix, CP）编码单载波(single carrier, SC)空间复用多输入多输出（multiple-input multiple output, MIMO）系统,基于变分推理,本文提出一种新的低复杂度压扩变换Turbo频域均衡（Turbo frequency domain equalization, TFDE）算法。相对于传统的TFDE算法,文中算法有两点明显不同,一是采用解码器压扩后验信息,计算软输入软输出（soft in soft out, SISO）频域均衡器（frequency domain equalizer, FDE）的数据先验均值和方差矩阵,二是采用SISO FDE外部数据均值、方差以及解码器压扩外信息,计算解码器先验信息。分析和仿真结果表明,这种新的TFDE算法在误码率（bit error rate, BER）性能、迭代收敛速度和总体计算复杂度方面均优于传统的MIMO TFDE算法。     

非线性时滞系统的一种新型稳定模糊控制方案

针对非线性时滞系统,基于模糊动态模型,采用分段Lyapunov函数法,设计出一种新型稳定模糊控制方案,克服了采用公共Lyapunov函数法的并行分配补偿法中需求解公共正定矩阵的困难。新方法只要求一系列正定矩阵满足一系列Lyapunov不等式即可,进一步扩大了解的存在性,减小了保守性。采用线性矩阵不等式法,避免了采用公共Lyapunov函数法中繁琐的Riccati方程求解。     

一类时滞递归神经网络间的鲁棒自适应同步

针对一类具有不同吸引子的时滞递归神经网络间的同步问题,提出了一个自适应同步控制策略,建立了具有不同吸引子的两个神经网络间全局鲁棒同步的一个新判据。所提出的自适应同步控制策略不仅适用于结构已知的神经网络,而且也适用于不同结构和部分参数已知的神经网络,且对未知参数部分,由自适应更新律来辨识其参数。所提出的同步判据容易验证和控制律容易实现,数值仿真验证了所提方法的有效性。     

T-S模糊系统的一种新型PDC鲁棒模糊控制器设计

针对一类模有界的参数不确定Takagi-Sugeno(T-S)模糊系统,在分析模糊系统前提规则结构的基础上,设计了一种新的并行分配补偿(PDC)控制器,研究了其鲁棒控制问题。基于分段Lyapunov稳定性理论,导出了线性矩阵不等式(LMI)形式的鲁棒控制器设计方法。该方法充分利用了模糊系统隶属度函数的结构信息,降低了采用线性矩阵不等式方法求解的难度。仿真实验证明,通过该方法设计的模糊控制系统,具有良好的鲁棒性能,控制效果良好。     

基于高增益观测器的非线性系统自适应模糊滑模控制

针对一类有界的不确定非线性系统,基于高增益观测器并结合自适应模糊逻辑系统和滑模控制,提出了一种基于高增益观测器的自适应模糊滑模控制方案。该方案不需要系统状态可测的条件,而是通过设计高增益观测器来估计系统的状态并能保证观测误差一致最终有界。基于李亚普诺夫函数方法,给出了自适应模糊滑模控制律以及在线调节的参数自适应律。所提出的控制方案不但能使闭环系统稳定,而且保证了跟踪误差的一致最终有界性。仿真结果进一步验证了该控制方案的实用性和有效性。     

解不确定型决策问题的投影寻踪方法

不确定型决策问题在系统工程理论与实践中具有重要意义 ,其益损值矩阵反映了该问题的复杂性和不确定性 ,同时也反映了决策者所面临的收益机会和损失机会的风险信息 ,目前常用方法利用益损值矩阵的信息都不充分 .指出求解该问题的实质 ,就是如何把益损值矩阵转换为压缩向量 ,该压缩向量的最大分量所对应的方案就是所求的最优方案 .为全面处理这种机会风险 ,提出了基于遗传算法的投影寻踪方法的新途径 .研究结果表明 ,根据益损值矩阵所反映的收益机会的风险与损失机会的风险的对比情况 ,投影寻踪方法既可积极地也可稳妥地选取最优方案 ,利用益损值矩阵的信息比常用方法充分 ,可根据决策者所面临的机会风险能进能退.     

一种时滞相关非脆弱模糊控制器的设计

研究了一类带有时变时滞的离散模糊双线性系统的时滞相关非脆弱控制问题。引入自由权值矩阵并定义一种新型的Lyapunov函数,在控制器存在加性不确定的情况下,得到了保守性小的时滞相关渐近稳定的充分条件。通过附加矩阵,将所得到的稳定条件转换为线性矩阵不等式(linear matrix inequality, LMI)形式,非脆弱控制器可由LMI的解得到。数例仿真验证了该方法的有效性。     

Cochannel interference cancelation for multiple access systems

Many properties of frequency-hopped spread-spectrum multiple access (FH/SSMA), such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochannel interference (CCI) can seriously harm the system's performance. On the basis of the analysis of the CCI pattern of frequency hopped multiple access signal, a new multiuser detection algorithm for canceling the CCI in frequency hopped multiple access systems is proposed. In the proposed scheme, the CCI is canceled by first detecting the frequency hopping slot, and then classifying and regenerating the candidates of the interference pattern from the time-frequency matrix. Both the theoretical analysis and computer simulation results show that compared to the conventional detector and Mabuchi's detector, this new multiuser detector has lower complexity, better convergence stability, and is suitable for both additive white Gaussian noise (AWGN) channels and Rayleigh fading channels.     

Power allocation for MIMO-OFDM systems with multi-user decoupling and scheduling

1 .INTRODUCTIONRecentinformation-theoretic results haveshownthat multi-ple-input multiple-output ( MI MO) channels have a greatpotential to i mprove spectral efficiency in rich scatteringwireless channels[1 ,2].Si multaneously,orthogonal frequen-cy division multiplexing (OFDM) has gained anincreasinginterest as a promisingalternativeforfuture highrate wide-band wireless systems because of its lowcomplexity signalprocessingto counteract frequency selectivity. The combi-nationof MI MOsy…     

基于OFDM系统的空时频分组编码方案

提出了一种空时频分组编码方案,其设计思路是:接收端通过子信道的相关特性确定不相关子载波组,并反馈给发射端;发射端基于反馈信息,利用星座旋转预编码矩阵和空时分组编码技术构建空时频分组编码。该方案只反馈子信道的相关性而无需反馈整个信道信息,可应用于任意数量的发射/接收天线,能获得极高的分集增益和带宽效率,且只有较低的解码复杂度。在瑞利衰落环境下的仿真结果证实了此方案的鲁棒性。