事件触发下网络控制系统的动态输出反馈控制

研究了基于事件触发的网络控制系统(NCSs)的动态输出反馈控制(DOFC).通过综合考虑NCSs中的网络诱导延迟和时序错乱的问题,建立了包含事件触发机制和DOFC的闭环模型.与传统的静态控制不同,DOFC可以忽略极点配置受限的问题,增加系统的适应性范围.仿真结果验证了所提出的事件触发机制和DOFC的有效性.     

受控的大电流紧凑型汽车动力系统

功率控制设备的用户使用第三方系统已经很多年了,因为它们能够降低开发成本,缩短产品的面市时间,易于满足鉴定标准。由于规范要求越来越多,有必要采用更高集成度以及对更加严格地控制系统中的所有元件。     

具有高阶分集的协作系统中的功率分配算法

针对具有高阶分集的协作系统采用平均功率分配(EPA),导致系统平均误比特率性能较低的问题,提出了以最小化系统平均误比特率为目标的功率优化分配(OPA)算法。首先,推导了协作系统端到端误比特率的上界以及高信噪比条件下的渐近近似。在此基础上,推导了使系统平均误比特率最小的最优功率分配系数的闭式表达式。仿真结果表明,在保证总发射功率一定的条件下,所提功率分配算法相比平均功率分配可以有效降低系统的平均误比特率。     

电动汽车用动力电池环境下的安全性能

随着以锂离子蓄电池为代表的新能源汽车的推广与普及,就动力电池本身来说,在不同环境条件下的安全使用是至关重要的,其安全性能应结合电动汽车用锂离子蓄电池在充放电、行驶、环境温度变化和意外事故发生时可能出现的各种情况下,确保锂离子蓄电池进行有效的防护,不爆炸,不起火,避免灾害的发生.     

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.     

Passivity-based Control for Markovian Jump Systems via Retarded Output Feedback

This paper is concerned with the problem of passivity-based control for Markovian jump systems via retarded output feedback controllers. A delay-dependent passivity criterion is obtained in terms of linear matrix inequalities. Based on this, a sufficient condition is proposed for the design of a retarded output feedback controller which ensures that the closed-loop system is passive. By using the sequential linear programming matrix method, a desired retarded output feedback controller can be constructed. Numerical examples are provided to demonstrate the advantage and effectiveness of the proposed method.     

非线性闭环系统的虚拟参考反馈校正控制设计

针对闭环非线性系统中的控制器为一非线性函数的情况,采用虚拟参考反馈校正控制的设计原理,根据控制器的输入—输出观测数据构造一个基于输出数据的线性仿射函数。通过最小化逼近误差,利用系统辨识的参数估计方法求取线性仿射函数中可调参数权值,从而采用一个含可调参数权值的线性仿射形式来逼近原非线性控制器,通过对参数权值的调整使得逼近误差较小,并给出参数权值的凸优化求解过程。最后用仿真算例验证方法的有效性和可行性。     

Power Control Algorithms for Satellite Communication Systems

Three different ground terminal transmit power control concepts for a Satcom system are examined. The effectiveness of constant satellite power (CSP) sharing among the carriers and adaptive satellite power (ASP) sharing is compared with constant ground terminal transmit power (CTP). It is shown that ASP offers substantial advantages over CSP in combating environmental degradations and that both can increase link availability with respect to the constant power (CTP) case. The effectiveness of the ASP control technique is shown to depend on the interconnectivity of the network if multidestinational carriers are used. The measurements required for system control, as well as their accuracies, are described.     

Uplink Power Control for MIMO-OFDMA Cellular Systems

In this paper, we propose a novel uplink power control algorithm, SMST, for multiple-input multiple-output orthogonal frequency-division multiple access (MIMO-OFDMA).We perform an extensive system-level simulation to compare different uplink power control algorithms, including the FPC adopted in 3GPP LTE and LTE-Advanced. Simulations show that SMST adopted in IEEE 802.16m outperforms other algorithms in terms of spectral efficiency, cell-edge performance, interference control, and trade-off control between sector-accumulated throughput and cell-edge user throughput. The SMST performance gain over FPC can be more than 40%.     

Dynamic Call Admission Control for Centralized CDMA Systems

Spectral efficiency of WCDMA based spread spectrum 3G/4G air interface technology is highly influenced by the common channel interference, hence the applied Call Admission Control method has great importance because it determines the number of active users admitted to the network. In this paper we present a dynamic air interface CAC algorithm which provides efficient usage of radio resources and allows real-time adaptation to the always changing network parameters. Required CAC parameters are derived for generalized multiplicative fading and generalized memory-less traffic sources. In order to validate its capabilities our proposed CAC method was investigated with ON/OFF traffic sources and lognormal fading channels.     

Feedback Linearization Control of Three-Phase UPS Inverter Systems

In this paper, a feedback linearization technique is proposed to control the output voltage control of three-phase uninterruptible power supply systems. First, a nonlinear model including the output $LC$ filters is derived from the power balance condition between the inverter output terminal and the load side. Then, input–output feedback linearization is applied to the nonlinear model to make it linear. The controller of the linearized model is designed by linear control theory. The tracking control law is obtained with a pole placement technique. It is shown experimentally that the proposed control scheme gives high dynamic responses in response to load variation as well as a zero steady-state error.      

Finite-Time Stability and Dynamic Output Feedback Stabilization of Stochastic Systems

This paper is concerned with finite-time stability and dynamic output feedback stabilization for Itô type stochastic systems. First of all, it presents a sufficient pth moment finite-time stability criterion of nonlinear stochastic systems. When linear stochastic systems are considered, a finite-time stability condition in the sense of mean square is obtained by choosing a quadratic Lyapunov function. Then, a dynamic output feedback controller is designed to mean-square finite-time stabilize the linear stochastic systems under consideration. Furthermore, the proposed method is extended to finite-time dynamic output feedback control for a class of linear stochastic retarded systems. Numerical examples are finally provided to show the effectiveness of the approach.     

一种多中继协作系统中的功率分配算法

提出了多中继无线通信系统的模型,研究其源节点和各中继节点间功率分配对系统容量的影响,在总功率一定的情况下,探讨了以容量最大化为准则的功率分配算法。对采用非再生协作中继方式的多中继协作通信系统进行了容量分析,并提出了一种低复杂度的最优功率分配算法(Optimum Power Allocation,OPA)。仿真结果表明,该算法相对于平均功率分配算法(Average Power Allocation,APA),系统容量得到了显著提高,在信道条件差的情况下,性能提高更明显。     

Low-Rate-Feedback-Assisted Beamforming and Power Control for MIMO-OFDM Systems

This paper proposes a novel solution to the problem of beamforming and power control in the downlink of a multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system. This solution is developed in two steps. First, we describe an adaptive beamforming technique that, using a stochastic gradient method, maximizes the power delivered to a mobile terminal. In the proposed solution, perturbed precoding matrices are time multiplexed in the information signal transmitted to a mobile terminal; then, the mobile terminal informs the transmitter, via a single feedback bit, about the perturbation delivering the larger power. This approach does not need pilot symbols and uses quasi–Monte Carlo methods to generate the required perturbations with the relevant advantages of improving the downlink spectral efficiency and reducing the system complexity with respect to other competing solutions. Then, we propose a novel power-control algorithm that, selecting a proper transmission energy level from a set of possible values, aims to minimize the average bit error rate. This set of levels is generated on the basis of the channel statistics and a long-term constraint on the average transmission power. Numerical results evidence the robustness of the proposed algorithms in a dynamic fading environment.      

Joint Optimization of Subchannel Reassignment and Power Adaptation for Multicarrier Cooperative Systems

An amplify-and-forward multicarrier cooperative system was proposed in this paper. The optimal resource-allocation problem was investigated in terms of improving data rate. An effective resource-allocation algorithm was proposed based on three techniques, adaptive modulation, subchannel reassignment design and transmit power adaptation. The designed subchannel reassignment not only increases the average data rate, but also raises the threshold of ＂water-filling＂ in optimizing power allocation that can further increase data rate. Since the power allocation is based on the designed subchannel reassignment, the complexity of the proposed algorithm is reduced greatly. Simulation results show that the proposed algorithm effectively increases the system＇s average data rate.     

Game-Theoretic Joint Power Allocation and Beamforming for Cognitive MIMO Systems with Finite Feedback

In the paper, we consider the imperfect channel state information (CSI) in practical cognitive MIMO systems. We first analyze the feedback of quantified CSI from the primary user (PU) and propose a joint power allocation and beamforming algorithm via game theory. Compared with the game under the condition of perfect CSI, new utility function and cost function are constructed under imperfect CSI. We analyze the error introduced from the uniformly quantified CSI and obtain new constraints. Besides, existence of the Nash equilibrium in case of both perfect CSI and imperfect CSI are proven. We propose a new iterative algorithm to reach the Nash equilibrium (NE). Simulation results show that the proposed algorithm can converge quickly.     

Multidimensional Linear Feedback Control Systems and Interpolation Problems for Multivariable Holomorphic Functions

This paper examines the connections between feedback stabilization and H⁸ control, model matching problems and multivariable Nevanlinna-Pick interpolation problems for multidimensional or n-D linear systems.