研究隐蔽式攻击下网络化控制系统状态与执行器故障的联合区间估计问题.首先,根据隐蔽式攻击信号的特性,得到隐蔽式攻击信号的上下界信息;然后,将执行器故障视为增广状态,构造与原系统等价的增广系统,基于所得到的增广系统和隐蔽式攻击信号的上下界信息,利用L∞滤波理论设计鲁棒增广状态区间观测器,从而得到系统状态与执行器故障的联合区间估计;最后,通过仿真实例验证所提出方法的有效性和优越性.

This article investigates fault-tolerant finite-time consensus (FTC) problems of single/double-integrator multi-agent systems (MASs) with partial agents subject to asynchronous self-sensing function failures (SSFFs). First, the strategy named DRMNNS is developed to recover the connectivity of network topology among normal agents by converting asynchronous SSFFs into multiple piecewise synchronous SSFFs and using multi-hop communication (MHC) together with agents subject to SSFFs as routing nodes. Second, by employing the state and input information of all agents in minimum-hop normal neighbor set (MHNNS) of an agent subject to SSFF and utilizing the history information of the agent subject to SSFF for computing its state information at the instants when its MHNNS changes, two switching fault-tolerant FTC protocols with single/double time-varying gains are designed, respectively, for single/double-integrator MASs. Third, convergence analysis is carried out by separately investigating the closed-loop dynamics of normal agents and the open-loop dynamics of agents subject to SSFFs, and convergence conditions in terms of time-varying gains are derived. It turns out that single/double-integrator MASs under asynchronous SSFFs using the proposed DRMNNS strategy and two fault-tolerant FTC protocols with proper time-varying gains can reach FTC/finite-time dynamical consensus (FTDC), respectively. Finally, comparison numerical simulations are provided to illustrate the effectiveness of the theoretical results.

The active fault-tolerant control under random loss of measurement data issue is investigated for a class of networked control systems with actuator faults and partially decoupled disturbances.First, the equivalent state-augmented systems are derived using an appropriate model transformation, and an unknown input observer（UIO） is designed to simultaneously estimate system states and fault signals under random packet dropouts. Next, considering the online estimation of states and fault, an active fault-tolerant control law is developed using a signal compensation strategy. Intensive stability analysis is performed to obtain sufficient conditions to further generate the desired observer and controller. Furthermore, the corresponding optimal parameters can be co-designed by solving the matrix inequality with convex constraints online. Finally, a simulation example of the jet engine model is provided to demonstrate the effectiveness of the proposed fault estimation and fault-tolerant control method.

Vanadium oxide (VOx) microbolometers enable the construction of high-performance yet low-cost and uncooled imaging detectors in the mid-infrared spectrum. Typical micro-bolometers are broadband sensors with no polarization selectivity. Thus, imaging detectors based on microbolometers have to use separate spectral and polarization filters to select the target spectral bands and polarization states, and the resulting systems are complicated and bulky. Here we demonstrate that by using metamaterial absorbers (MAs), which are arrays of optical resonators with sub-wavelength dimensions and spacing, we simultaneously tailor the VOx microbolometers' spectral and polarization responses, the need for separate spectral filters and polarizers can be mitigated. The MAs selectively absorb the TM polarization component of the incident light in a spectral band with tunable central wavelength and bandwidth while rejecting the TE polarization component. Two MAs with average TM absorption of 0.8322 in the 5.150 µm - 6.422 µm band and 0.7720 in the 5.867 µm - 7.467 µm band are fabricated, and the polarization extinction ratio (PER) are 42.24 and 42.65, respectively. The MAs are applied to VOx micro-bolometers, and the measured detector responses agree well with the absorption spectra of the MAs. The achieved peak responsivities of two fabricated detectors are 1.0 V/W at 6.0 µm and 1.46 V/W at 6.8 µm, respectively. And the two detectors achieve a D* of 6.94×105 cm·Hz1/2W-1 at 11Hz and 9.95×105 cm·Hz1/2W-1 at 36Hz, respectively. Our work paved the way towards large format room temperature multi-spectral infrared polarization imaging detector.

SummaryThis article investigates the fault detection problem in finite‐frequency domain for a class of nonlinear networked systems under stochastic cyber‐attacks. A novel adaptive event‐triggered scheme is introduced to mitigate the transmission burden of the network. A unified measurement model is proposed to take the randomly occurring cyber‐attacks and the transmission delays into account simultaneously. Under the consideration of fault sensitivity and disturbance robustness, the addressed fault detection problem is converted into an auxiliary filtering problem by properly augmenting the states of the original system and the fault detection filter. Intensive stochastic analysis is carried out to obtain sufficient conditions for the existence of the desired fault detection filter, and the corresponding optimal filter parameters can be easily derived by solving a convex optimization problem. Finally, an illustrative example is presented to show the effectiveness and applicability of the proposed method.

: This paper investigated the fault detection problem in finite-frequency domain for nonlinear networked systems under stochastic cyber-attacks. To save limited network resource, this paper introduced a novel dynamic event-triggered scheme. Firstly, under the consideration of fault sensitivity and disturbance robustness, the paper converted the addressed fault detection problem into an auxiliary / H H −  filtering problem by augmenting the states of the original system and the fault detection filter. Taking sector bounded nonlinearity and stochastic cyber-attacks into consideration, the design of H − performance index included the frequency characteristics of fault signals. Combined with finite-frequency input characteristics, the paper proposed the joint design algorithm for fault detection filter and dynamic event-triggered scheme under the finite-frequency fault input. Finally, a simulation example of stirred tank reactor system verified the effectiveness of the proposed method.

This paper investigates the fault detection problem in finite-frequency domain for networked singularly perturbed systems. A novel dynamic event-triggered scheme is introduced to mitigate the transmission burden of the network. Under the consideration of fault sensitivity and disturbance robustness, the addressed fault detection problem is converted into an auxiliary H − / H ∞ filtering problem by properly augmenting the states of the original system and the interval observer. In addition, the residual generated by the interval observer can be directly utilized for fault detection decision-making instead of designing the residual evaluation function and threshold. Finally, simulation results of vehicle lateral dynamic systems are provided to illustrate the effectiveness and applicability of the proposed method.

We designed and fabricated a metamaterial-integrated vanadium oxide microbolometer for dualband infrared polarization detection. The experimental spectral and polarization responses agree with the design. Our work paved the way towards multi-spectral infrared polarization imaging detector.

This paper addresses the joint state and fault estimation problem for a class of discrete-time networked systems with unknown measurement delays. A novel augmented observer is developed to simultaneously estimate system states, fault signals and the perturbed term caused by measurement delays. For this purpose, an augmented descriptor system is first established by considering the faults and the perturbed term as auxiliary state vectors. Then, a modified state-space observer is constructed to estimate the extended state. Intensive stability analysis is carried out to obtain the sufficient condition for the existence of the desired estimator, and the corresponding optimal observer parameters can be co-designed by solving a convex optimization problem. Finally, a numerical example is exploited to illustrate the effectiveness of the proposed joint estimation scheme.

现代控制理论作为自动化和电气类专业的一门重要专业基础课,它着重培养学生系统建模、系统分析与系统综合方面的能力.该课程内容蕴含着丰富的思政元素,授课过程中通过思政案例的讲解,能够在潜移默化中引导学生践行社会主义核心价值观,激发学生的爱国热情与社会责任感,培养出具有"工匠精神"的新工科人才,从而实现知识传授与价值引领的协同育人目标.

Plasmonic metamaterial is a new class science which can regulate the electromagnetic response characteristics, including frequency, phase and polarization characteristics, by the specific design of structure and distribution of materials. But how to design the structure and material effectively becomes a issue worth studying. Inverse design has experienced rapid development in the past 20 years. When we applied some algorithms into the design of metamaterial, the efficiency can be improved greatly. In this paper, we proposed and improved a fully automatic genetic algorithm for the optimization of polarization-selective broadband absorber for 3μm-5μm, and we successfully achieved an average absorption of up to 0.7522 in 3-5um for transverse magnetic wave.

Mid-infrared imaging detectors are essential tools for many applications because they can visualize the objects in the dark via thermal radiation. However, these detectors have to pair with separate spectral and polarization filters to select the target spectral bands and polarization states, resulting in complicated and bulky imaging systems. One way to mitigate the need for separate spectral filters and polarizers is to use metamaterial absorbers, which are arrays of optical resonators with sub-wavelength dimensions and spacing, to tailor the responses of the detector pixels. Here we report an intelligent program based on the genetic algorithm that automates the design and optimization of a metal-insulator-metal based metamaterial absorber with multi-sized nanostrip antennas as the top layer. The program starts from a randomly generated pattern of the top antenna layer, and it iteratively approaches the optimized designs of two polarization selective MIM absorbers with wideband high absorption in the specified 3-5 (MWIR) band and 8-12 µm (LWIR) band. The measured absorption spectra of the two optimized designs agree well with the simulated results. The influences of the incident angle of light, the finite size of detector pixels, and the air gap between the neighboring pixels on the spectral absorption are numerically evaluated.

针对基于Round-Robin通信协议网络化控制系统的鲁棒故障检测问题,考虑传感器饱和以及外部干扰,提出了一种通信协议约束下故障检测滤波器的设计方法.利用李亚谱诺夫稳定性理论和线性矩阵不等式技术得到故障检测滤波器存在的充分条件,通过求解具有凸约束的优化问题得到最优滤波器参数.所设计的故障检测滤波器不仅能够确保滤波误差系统均方渐进稳定且有较强的扰动抑制能力.通过数值仿真和DTS200三容水箱液体渗漏检测实验验证了该方法的有效性.

研究了一类具有丢包的状态时滞的线性参数变化系统(Linear Parameter-Varying Systems,LPV)离散时间系统的H∞控制问题,此类LPV离散系统的时滞和状态矩阵是随参数变化的确定函数,该参数是可测的且不断变化.基于此,可以给出一种与参数相关的且满足H∞性能指标的准则.此准则具体是通过添加一个附加矩阵,从而解除了原有的系统矩阵与含有参数的Lyapunov函数之间的耦合.在此基础上设计了此类系统的状态反馈控制器,然后,利用线性矩阵不等式技术,求得控制器存在的充分条件,进一步转化可以得到不等式的解存在条件.最后,用实际的例子仿真验证了此方法的有效性.

In this paper, a new observer-based H∞ controller design method is developed for a class of time-varying net-worked control systems subject to high-rate communication network and Round-Robin(RR)protocol over a finite-horizon. The system under investigation involves multiplicative noise, stochastic time-delays and quantization effects. By applying Lyapunov stability theory and Linear Matrix Inequality(LMI)technique, a sufficient condition for the existence of the finite-horizon H∞ controller is derived. The corresponding parameters of the observer and controller are obtained via resorting to a set of recursive matrix inequalities based on Cone Complementarity Linearization(CCL)method. The proposed controller can ensure both the stability and the prescribed H∞ performance index of the closed-loop system over a given finite horizon. A simulation example is finally utilized to illustrate the effectiveness of the proposed controller design scheme.

In this paper, the fault detection (FD) problem is investigated for networked control systems with random packet losses, stochastic time-delays, sensor saturation as well as randomly occurring faults. A series of random variables is utilized to describe the occurring probability of packet losses, time-delays and faults where all the variables are independent but satisfy the Bernoulli distribution. The measured output is subject to sensor saturation which is described by sector-nonlinearities. Then the mathematical model for networked control systems is established. The aim of this paper is to design an FD filter such that, for unknown input, the FD problem is converted into H-infinity filtering problem and, the error between the residual signal and the fault signal is made as small as possible. By Lyapunov stability theory and linear matrix inequalities (LMIs) method, sufficient conditions for the existence of the desired FD filter are established. Finally, a numerical simulation is presented to verify the effectiveness and usefulness of the designed method.

Metamaterial absorbers, consisting of assembling arrays of optical resonators with subwavelength dimensions and spacing, allow efficiently absorption electromagnetic radiation by leveraging the strong electrical and magnetic resonances. Beyond the enhanced absorption, there is a growing interest to realize multi-functional absorbers, for example, absorbers with extended bandwidth, strong polarization extinction ratio, to name a few. Traditionally, designing multi-functional absorbers require complex brute-force optimizations with sizable parameter space, which turn out to be rather inefficient. Here, using the particle swarm optimization algorithm, we design and experimentally demonstrate broadband and highly polarization selective mid-IR metal-insulator-metal absorbers, covering the technologically important 3-5 μm atmospheric transparency band. With spectrally averaged absorption exceeding 70%, a high polarization extinction ratio of 40.6 is concurrently achieved by the algorithm. We also investigate the incident angle dependence of the spectral absorption and clarify the origin of optical losses. By integrating with the growing range of mid-IR detectors and imagers, our devices can enable new applications such as mid-IR full Stokes imaging polarimetry for remote sensing.

This paper is concerned with the fault detection problem for a class of continuous-time linear parameter-varying systems with signal transmission delays. An effective event-triggered communication scheme is introduced to reduce the burden of the shared network where the current sampled data will be sent only when the certain condition is satisfied. By properly designing a novel fault detection filter and augmenting the states of the original system, the addressed fault detection problem can be transformed into a \(H_\infty \) filtering problem for the filtering error system with uncertain parameters. According to the parameter-dependent Lyapunov–Krasovskii functional method and free-weighting matrix technique, the sufficient conditions, which guarantee the filtering error system satisfying the prescribed \(H_\infty \) performance constraint, are derived in the form of parameterized linear matrix inequalities. The basic functions and gridding technique are used to deal with the corresponding parameterized convex problem. Here, the LPVTools is used to convert the infinite-dimensional feasibility conditions into a finite-dimensional set of LMIs. Then, the MATLAB LMI toolbox is applied for solving the LMI problem of finite dimensions. Moreover, the explicit expressions of the target filter parameters are also obtained. Finally, two simulation examples are provided to illustrate the validity of the proposed fault detection method.

The problem of observer-based robust non-fragile dissipative control is studied for a class of nonlinear discrete-time systems with parameter uncertainties.A Bernoulli distributed sequence is introduced to describe the random packet dropout occurring either in the sensor-to-controller channel or controller-to-actuator channel.By constructing appropriate Lyapunov functions,and utilizing the linear matrix inequality (LMI) method,a sufficient condition for the existence of the desired non-fragile dissipative controller is established,and the controller parameters can be obtained by solving a feasible problem with convex constraints.The designed non-fragile controller could guarantee the exponential stability and the strict dissipativity in the mean-square sense of closed-loop systems.Finally,a numerical example is provided to demonstrate the effectiveness and superiority of the proposed design method.