Recursive Filtering for Stochastic Systems With Filter-and-Forward Successive Relays

In this paper, the recursive filtering problem is considered for stochastic systems over filter-and-forward successive relay (FFSR) networks. An FFSR is located between the sensor and the remote filter to forward the measurement. In the successive relay, two cooperative relay nodes are adopted to forward the signals alternatively, thereby existing switching characteristics and inter-relay interferences (IRI). Since the filter-and-forward scheme is employed, the signal received by the relay is retransmitted after it passes through a linear filter. The objective of the paper is to concurrently design optimal recursive filters for FFSR and stochastic systems against switching characteristics and IRI of relays. First, a uniform measurement model is proposed by analyzing the transmission mechanism of FFSR. Then, novel filter structures with switching parameters are constructed for both FFSR and stochastic systems. With the help of the inductive method, filtering error covariances are presented in the form of coupled difference equations. Next, the desired filter gain matrices are further obtained by minimizing the trace of filtering error covariances. Moreover, the stability performance of the filtering algorithm is analyzed where the uniform bound is guaranteed on the filtering error covariance. Finally, the effectiveness of the proposed filtering method over FFSR is verified by a three-order resistance-inductance-capacitance circuit system.

     

Neural-Network-Based Control for Discrete-Time Nonlinear Systems with Input Saturation Under Stochastic Communication Protocol

In this paper,an adaptive dynamic programming(ADP)strategy is investigated for discrete-time nonlinear systems with unknown nonlinear dynamics subject to input saturation.To save the communication resources between the controller and the actuators,stochastic communication protocols(SCPs)are adopted to schedule the control signal,and therefore the closed-loop system is essentially a protocol-induced switching system.A neural network(NN)-based identifier with a robust term is exploited for approximating the unknown nonlinear system,and a set of switch-based updating rules with an additional tunable parameter of NN weights are developed with the help of the gradient descent.By virtue of a novel Lyapunov function,a sufficient condition is proposed to achieve the stability of both system identification errors and the update dynamics of NN weights.Then,a value iterative ADP algorithm in an offline way is proposed to solve the optimal control of protocol-induced switching systems with saturation constraints,and the convergence is profoundly discussed in light of mathematical induction.Furthermore,an actor-critic NN scheme is developed to approximate the control law and the proposed performance index function in the framework of ADP,and the stability of the closed-loop system is analyzed in view of the Lyapunov theory.Finally,the numerical simulation results are presented to demonstrate the effectiveness of the proposed control scheme.     

A Comprehensive Overview of Cyber-Physical Systems: From Perspective of Feedback System

Cyber-physical systems (CPS) are characterized by integrating cybernetic and physical processes. The theories and applications of CPS face the enormous challenges. The aim of this paper is to provide a latest understanding of this emerging multi-disciplinary methodology. First, the features of CPS are described, and the research progresses are summarized from different components in CPS, such as system modeling, information acquisition, communication, control and security. Each part is also followed by the future directions. Then some typical applications are given to show the prospects of CPS.      

A Priority-aware Frequency Domain Polling MAC Protocol for OFDMA-based Networks in Cyber-physical Systems

Wireless networking in cyber-physical systems (CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and reliability constraints. One of the fundamental considerations for enabling CPS networks is the medium access control protocol. To this end, this paper proposes a novel priority-aware frequency domain polling medium access control (MAC) protocol, which takes advantage of an orthogonal frequency-division multiple access (OFDMA) physical layer to achieve instantaneous priority-aware polling. Based on the polling result, the proposed work then optimizes the resource allocation of the OFDMA network to further improve the data reliability. Due to the Non-polynomial-complete nature of the OFDMA resource allocation, we propose two heuristic rules, based on which an efficient solution algorithm to the OFDMA resource allocation problem is designed. Simulation results show that the reliability performance of CPS networks is significantly improved because of this work.      

带未知通信干扰和丢包补偿的多传感器网络化不确定系统的分布式融合滤波

研究了带有未知通信干扰、观测丢失和乘性噪声不确定性的多传感器网络化系统的状态估计问题.通过白色乘性噪声描述系统状态和观测中的随机不确定性,采用一组服从Bernoulli分布的随机变量描述网络传输过程中存在的观测丢失现象,且数据传输中存在未知的网络通信干扰.当发生丢包时,以当前丢失观测的预报值进行补偿.对每个单传感器子系统,应用线性无偏最小方差估计准则设计了不依赖于未知通信干扰的最优线性滤波器.推导了任两个局部滤波误差之间的互协方差阵.进而,应用矩阵加权融合估计算法给出了分布式融合状态滤波器.仿真例子验证了算法的有效性.     

小型集散控制系统的通信协议构造

阐述了基于小型集散控制系统的通信协议的体系结构，讨论了通信协议的实时响应方案可靠性。     

A Survey of Cyber Attacks on Cyber Physical Systems: Recent Advances and Challenges

A cyber physical system (CPS) is a complex system that integrates sensing, computation, control and networking into physical processes and objects over Internet. It plays a key role in modern industry since it connects physical and cyber worlds. In order to meet ever-changing industrial requirements, its structures and functions are constantly improved. Meanwhile, new security issues have arisen. A ubiquitous problem is the fact that cyber attacks can cause significant damage to industrial systems, and thus has gained increasing attention from researchers and practitioners. This paper presents a survey of state-of-the-art results of cyber attacks on cyber physical systems. First, as typical system models are employed to study these systems, time-driven and event-driven systems are reviewed. Then, recent advances on three types of attacks, i.e., those on availability, integrity, and confidentiality are discussed. In particular, the detailed studies on availability and integrity attacks are introduced from the perspective of attackers and defenders. Namely, both attack and defense strategies are discussed based on different system models. Some challenges and open issues are indicated to guide future research and inspire the further exploration of this increasingly important area.      

大型电子投票表决系统通信协议的设计与实现

根据通信协议的分层结构,对物理层、数据链路层和应用层进行设计。实现了下位机（主控制器、分支控制器和表决器）的通信协议和上位机（计算机）的通信协议。该协议适用于计算机和单片机点对点通信的情况。本文所提出的通信协议的设计思想和思路方法对于相关设计和应用具有一定的参考意义和借鉴价值。     

基于Gauss-Hermite逼近的非线性加权观测融合无迹Kalman滤波器

对非线性多传感器系统,基于Gauss-Hermite逼近方法和加权最小二乘法,提出了一种具有普适性的非线性加权观测融合算法.该算法可将一个高维观测压缩为一个低维观测.在此基础上,结合无迹Kalman滤波器（Unscented Kalman filter,UKF）,提出了非线性加权观测融合无迹Kalman滤波器（WMF（Weighted measurement fusion）-UKF）.与集中式融合UKF（CMF（Centralized measurement fusion）-UKF）相比,该算法计算负担小且具有逼近的估计精度.特别是在传感器数量较大时,该算法在计算量上的优势更加明显.仿真例子验证了算法的有效性.     

离散随机线性系统最优滤波,预报和平滑估计的一种统一方法

基于射影理论及新息分析方法，讨论离散随机线性系统最优化状态估计问题。提出了一种统一处理最优滤波、预报和平滑估计的的新方法，证明了新算法的渐近稳定性。     

带未知模型参数和衰减观测率系统自校正分布式融合估计

研究了带未知模型参数和衰减观测率多传感器线性离散随机系统的信息融合估计问题.在模型参数和衰减观测率未知的情形下,应用递推增广最小二乘(Recursive extend least squares,RELS)算法和加权融合估计算法提出了分布式融合未知模型参数辨识器;应用相关函数对描述衰减观测现象的随机变量的数学期望和方差进行在线辨识.将辨识后的模型参数、数学期望和方差代入到最优分布式融合状态滤波器中,获得了相应的自校正融合状态滤波算法.应用动态误差系统分析(Dynamic error system analysis,DESA)方法证明了算法的收敛性.仿真例子验证了算法的有效性.     

群决策支持系统通信部件的研究与实现

群体间通信问题是群决策支持系统(group decision support system,简称GDSS)研究中所要考虑的一个重要问题.目前,实现群体间通信主要采用通用的群件产品,但这类产品协调通信慢,灵活性差,且不易集成,不适合应急GDSS的协同通信.为了寻找一种应急GDSS快速协调性通信的方式,该文研究了一种混合式GDSS网络通信结构,在重点分析GDSS协调性通信功能的基础上提出一种新的基于TCP/IP协议的GDSS 通信协议——GDSSTP(GDSS transmission protocol),给     

AMI通信网络中微功率无线通信的性能测试技术及系统研究

微功率无线通信是高级量测体系的主要通信方式之一,各厂家的通信模块性能不一,测试技术尚未形成统一的规范;设计了微功率无线通信的测试系统,由射频性能测试系统和协议一致性分析系统组成;系统采用屏蔽测试箱、多功能电磁波小室、综合测试分析仪、误码分析仪、标准协议信号源等模块组成,屏蔽箱对800 MHz频率以下的无线电信号有超过70dB的抑制,可以提供相对纯净的无线电暗室环境,减少外界无线电波的干扰;测试频率范围为30MHz~1GHz,提供66个测试频点,测试频率误差小于2ppm,误码测试精度小于0.001%,功率测试精度(闭环)为5%(0.2dB);实现了在实验室情况下对微功率无线网络性能的全面测试和评估,具备很好可操作性、便利性和可复现性。