Output Feedback Passification of Switched Continuous-Time Linear Systems Subject to Saturating Actuators

This paper is concerned with the output feedback passification of switched continuous-time linear systems with actuation saturation. A switching law and saturated output feedback controllers with the form of quasi-linear parameter-varying are designed such that the closed-loop switched system with actuator saturation is passive, and the system state remains inside an invariant ellipsoid, which meet the requirements of passivity and saturation simultaneously. Since the system state is often unavailable, we consider the issue of how to design dynamic output feedback controllers using only partial state measurements. Moreover, the switching law is designed to depend only on the state of the dynamic output feedback controllers, which renders the switched system passivity even the subsystems are non-feedback passive. Sufficient conditions for the existence of the switching and output feedback control law are derived in terms of linear matrix inequalities. Finally, a numerical example is given to show the effectiveness of the proposed method.     

多时滞离散切换系统反馈镇定

研究一类具有多时滞子系统的离散切换系统的稳定性分析和反馈镇定问题。通过状态变量的转换，将时滞切换系统变为不含时滞项的切换系统。以LMI形式给出了在任意切换信号作用下多时滞离散切换系统渐近稳定的充分性条件，以及系统状态反馈镇定、输出反馈镇定的控制器设计。并通过两个仿真实例验证所设计控制方案的有效性。     

基于确定性观测的压缩感知MIMO信道参数反馈

在实际资源受限(带宽受限或功率受限)的无线通信系统中,多径信道具有很强的稀疏特性,如何利用这一特点更加高效地将接收端获得的多径信道状态信息( CSI)进行压缩、反馈,是目前信道状态信息反馈技术的研究热点。针对现有多入多出( MIMO)信道状态信息反馈方法中随机观测矩阵需要较大存储空间的问题,引入了确定性Golay测量矩阵,提出了一种基于确定性观测的压缩感知MIMO多径信道参数反馈方法。在接收端对由信道估计得出的信道状态信息利用确定性Golay测量矩阵进行观测,将较少数目的观测值反馈到发送端,在发送端通过重构算法恢复出完全信道状态信息。仿真实验表明,与随机观测相比,采用确定性Golay观测矩阵的方法虽然需要的观测值数目会有所增加,但所需存储空间远小于随机观测矩阵,且利用确定性观测反馈信道状态信息的重构性能与随机观测矩阵相当。     

基于遗传搜索和有限反馈的酉阵设计

在MIMO系统中,酉阵主要应用于差分空时调制（DUSTM）及有限反馈预编码两个方面。DUSTM主要应用于无法获得信道状态参数（CSI）情况下,而有限反馈预编码则应用于完全或部分可获得CSI情况下。文中提出了一种基于实型＂频率＂系数的遗传搜索方法,即使在系统维数很大的情况下,运用该方法获得酉阵设计的码字性能优于由整型＂频率＂系数穷举搜索而获得的码字。     

基于状态空间法的MEMS静电驱动控制方案

采用状态空间分析法，研究MEMS静电驱动平行板结构的运动特性，实现了平行板机械子系统和静电子系统状态空间矩阵参数分离，制定了状态反馈控制方案以改善平行板系统的运动特性，在Simulink仿真平台上完成了控制方案的计算机仿真实验。结果表明，状态反馈控制方案能较好地提高系统的操作精度并改善瞬时特性。     

Design of multivariable systems using unity-rank state feedback: further results

The letter describes three applications of the degrees of freedom in the design of a unity-rank state feedback matrix for pole assignment in a multivariable system. These include sensitivity reduction of closed-loop poles and restrictions on the magnitudes of feedback gains and control inputs. The method is illustrated by a numerical example.     

基于状态空间法的MEMS静电驱动控制方案

采用状态空间分析法,研究MEMS静电驱动平行板结构的运动特性,实现了平行板机械子系统和静电子系统状态空间矩阵参数分离,制定了状态反馈控制方案以改善平行板系统的运动特性,在Simulink仿真平台上完成了控制方案的计算机仿真实验。结果表明,状态反馈控制方案能较好地提高系统的操作精度并改善瞬时特性。     

Impulsive Synchronization of Chaotic Lur'e Systems by Linear Static Measurement Feedback: An LMI Approach

In this brief, we consider impulsive control for master-slave synchronization schemes that consist of identical chaotic Lur'e systems. Impulsive control laws are investigated which make use of linear static measurement feedback, instead of full state feedback. A less conservative sufficient condition than existing results for global asymptotic impulsive synchronization is presented, in which synchronization is proven for the error between the full state vectors. And then an linear matrix inequality (LMI)-based approach for designing linear static output feedback impulsive control laws to globally asymptotically synchronize Lur'e chaotic systems is derived. With the help of the LMI solvers, we can easily obtain the linear output feedback impulsive controller and the bound of the impulsive interval for global asymptotic synchronization. The method is illustrated on Chua's circuit.     

Global Synchronization and State Tuning in Asymmetric Complex Dynamical Networks

A strategy to control the complex dynamical networks for global synchronization as well as to tune their synchronous states is presented based on linear state feedback controllers. The synchronous state can be changed from one system to other similar system just by choosing a suitable tuning matrix. Especially, some of the criteria are expressed in normal inequalities instead of matrix inequalities. Simulations are also done to verify the theoretical results.      

部分信道状态信息下多天线系统的最优发送

在实际的单用户多天线平坦衰落通信系统中,接收端往往具有理想的信道状态信息,而发送端只有来自接收端的部分信道状态信息反馈,因此在发送端信道模型假设为复高斯随机矩阵.在发射端具有信道协反差反馈或者均值反馈的情形下,对达到最大的信道容量即信息论角度的最优化问题进行了理论分析,研究了系统的最优发送方案.对目前的关于单方向发射的最优条件进行扩展,进一步推导了沿任意多个方向发送达到信道容量的条件.数值结果验证了分析结论.     

Simplified Lyapunov matrix equation with applications to the control of distributed-parameter systems

The Lyapunov matrix equation is shown to be of importance in generating the optimal gains for distributed-parameter feedback control systems with controllers based on the values of the state variables at discrete points. It is shown that the Lyapunov matrix equation can be considerably reduced for such systems. In a typical example, the number of unknowns is reduced from 1225 to 49.     

REALIZATION OF ARBITRARY TRANSFER MATRIX WITH ACTIVE MULTI-PORT NETWORK

A new simple method in which arbitrary transfer function matrix is realized withactive multiple port network instead of computer simulating is proposed. The active multipleport network is carried on through state feedback and state cross output for RC ladder network.The main process is to determine coefficients of each adder. Finally, an example is given forillustration.     

任意传递矩阵的多端口有源网络实现

本文提出用实际的多端口网络来实现任意传递矩阵的简捷方法,即通过RC梯形网络和输入输出加法器进行状态反馈和状态交叉输出的实现方法。主要工作是确定各加法器系数。     

3G LTE系统基于码本的自适应预编码方案

第三代移动通信系统长期演进(3G LTE)系统的下行链路传输中,基站端无法获知完全的信道状态信息(CSI),需要根据终端反馈的预编码序号从已有的码本中挑选合适的预编码矩阵进行信号处理。研究了多小区场景下基于有限信息反馈的码本选择算法,提出了一种单双流自适应的码本选择方案,分析了2×2天线情况下所提预编码算法的性能,通过计算机仿真给出了不同多天线预编码方案的性能对比。     

基于协作多点传输的非线性顽健预编码

A nonlinear robust precoding algorithm was proposed,which redesigned the feedback matrix,the forward matrix and the scaling matrix of the traditional tomlinson-harashima precoding algorithm based on the statistical characteristics of the downlink channel state information errors.Simulation results show that the nonlinear robust precoding algorithm can achieve better performance than the traditional linear and nonlinear precoding algorithms when the downlink channel state information errors exist.Due to the different downlink channel state information errors between user equipments in the coordinated multi-point transmission,the traditional “best-first” ordering algorithm was invalid.So an improved ordering algorithm was proposed to reduce the average bit error rate of the nonlinear robust precoding algorithm.     

On the Capacity and Design of Limited Feedback Multiuser MIMO Uplinks

The theory of multiple-input–multiple-output (MIMO) technology has been well developed to increase fading channel capacity over single-input–single-output (SISO) systems. This capacity gain can often be leveraged by utilizing channel state information at the transmitter and the receiver. Users make use of this channel state information for transmit signal adaptation. In this correspondence, we derive the capacity region for the MIMO multiple access channel (MIMO MAC) when partial channel state information is available at the transmitters, where we assume a synchronous MIMO multiuser uplink. The partial channel state information feedback has a cardinality constraint and is fed back from the basestation to the users using a limited rate feedback channel. Using this feedback information, we propose a finite codebook design method to maximize the sum rate. In this correspondence, the codebook is a set of transmit signal covariance matrices. We also derive the capacity region and codebook design methods in the case that the covariance matrix is rank one (i.e., beamforming). This is motivated by the fact that beamforming is optimal in certain conditions. The simulation results show that when the number of feedback bits increases, the capacity also increases. Even with a small number of feedback bits, the performance of the proposed system is close to an optimal solution with the full feedback.      

Improvement of State Feedback Controller Design for Networked Control Systems

A new method is proposed to improve the state feedback controller design for networked control systems (NCSs) taking both network-induced time delay and packet dropout into account in this paper. An appropriate Lyapunov functional is introduced to establish the improved sufficient stabilizability conditions for NCSs with memoryless state feedback controller by considering an additional useful term when estimating the upper bound of the derivative of Lyapunov functional and introducing new free weight matrices. Based on this less conservative existence condition, a networked controller design method is derived, which is equivalent to the solvability of a set of linear matrix inequalities. Numerical example is given to demonstrate the effectiveness and benefits of the proposed method.     

An LMI Approach to Optimal Guaranteed Cost Control of Uncertain 2-D Discrete Shift-Delayed Systems via Memory State Feedback

This paper deals with the problem of optimal guaranteed cost control via memory state feedback for a class of two-dimensional (2-D) discrete shift-delayed systems in Fornasini–Marchesini (FM) second model with norm-bounded uncertainties. A new criterion for the existence of memory state feedback guaranteed cost controllers is derived, based on the linear matrix inequality (LMI) approach. Moreover, a convex optimization problem with LMI constraints is formulated to design the optimal guaranteed cost controllers which minimize the upper bound of the closed-loop cost function. Illustrative examples demonstrate the merit of the proposed method in the aspect of conservativeness over a previously reported result.     

H-Infinity State Feedback Control for a Class of Networked Cascade Control Systems With Uncertain Delay

Based on practical industrial process control, a typical configuration for networked cascade control systems (NCCSs) is analyzed. This kind of NCCSs with state feedback controllers, in which the network-induced delay is uncertain and less than a sampling period, is studied. The sufficient condition for the stabilizability of the NCCSs without disturbances is proposed, and the state feedback stabilization control laws are derived via Lyapunov stability theory and linear matrix inequality (LMI) approach. For the NCCSs with disturbances, the criterion of its robust asymptotically stability is derived and the $gamma$ -suboptimal state feedback $H_{infty}$ control laws are designed. The $gamma$-optimal state feedback $H_{infty}$ control laws are also put forward by optimizing a set of LMIs. A simulation example of a NCCS for the main steam temperature in a power plant is given to demonstrate the effectiveness of the proposed approaches.      

Interference Alignment Algorithm Based on Feedback Concentration in D2D Communications

This paper proposed an effective interference alignment algorithm based on channel state feedback concentration (FCIA) for device-to-device (D2D) communications. The algorithm iteratively calculates the precoding matrix by using the global channel state information. Furthermore, as D2D discovery is the premise of the D2D communications, an effective interference alignment algorithm based on D2D discovery is also proposed. Simulation results show that, the proposed FCIA algorithm reduces the feedback overhead for transmission coordination compared with the existing full feedback based algorithm. The proposed interference alignment scheme based on D2D discovery feedback is compared with the existing D2D discovery scheme: it is found that although the discovery time slots has increased by about 6.2%, the sum rate achieved by interference alignment is improved by almost 50%.