LMI characterization of the strong delay-independent stability of linear delay systems via quadratic Lyapunov–Krasovskii functionals

In this note is proposed an analogue for linear delay systems of the characterization of asymptotic stability of the rational systems by the solvability of associated Lyapunov equation. It is shown that strong delay-independent stability of delay system is equivalent to the feasibility of certain linear matrix inequality (LMI), related to quadratic Lyapunov–Krasovskii functionals.     

Delay-independent decentralized stabilizer design for large interconnected power systems based on WAMS

Recent stabilizer design using wide-area measurement systems (WAMS) signals has been suggested to enhance the dynamic performance of large interconnected power systems. However, there is an unavoidable delay involved before these signals are received at the stabilizer site. Long time-delay may be detrimental to system stability and may degrade system performance. Therefore, the delay-independent robust control problem of large interconnected power systems based on WAMS is studied via H_∞ fuzzy control method. First, a set of equivalent Takagi–Sugeno (T–S) fuzzy model is employed to represent the large interconnected power systems. A wide-area state feedback decentralized control scheme is developed to stabilize the T–S fuzzy systems without any wide-area signals delay information such that the H_∞ performance is achieved. The H_∞ fuzzy robust control design problem is parameterized in terms of a linear matrix inequality (LMI) problem, and the LMI problem can be solved very efficiently using the convex optimization techniques. Finally, the performance of the robust control is studied using a fourteen-machine interconnected power system example.     

Delay-independent stability of moments of a linear oscillator with delayed state feedback and parametric white noise

The stability of a linear oscillator with delayed state feedback driven by parametric Gaussian white noise is studied in this paper. The first and second order moment equations of the system response are derived by using moment method and Itô differential rule. Based on the moment equations, the delay-independent stable conditions of both moments are proposed: For the first order moment, the sufficient and necessary condition that guarantee delay-independent stability is identified to that of the deterministic system; for the second order moment, the sufficient condition that ensure delay-independent stability depends on noise intensity. The theoretical results are also illustrated with numerical simulations.     

A distributed controller approach for delay-independent stability of networked control systems

This article introduces a novel distributed controller approach for networked control systems (NCS) to achieve finite gain L₂ stability independent of constant time delay. The proposed approach represents a generalization of the well-known scattering transformation which applies for passive systems only. The main results of this article are (a) a sufficient stability condition for general multi-input-multi-output (MIMO) input-feedforward-output-feedback-passive (IF-OFP) nonlinear systems and (b) a necessary and sufficient stability condition for linear time-invariant (LTI) single-input-single-output (SISO) systems. The performance advantages of the proposed approach are reduced sensitivity to time delay and improved steady state error compared to alternative known delay-independent small gain type approaches. Simulations validate the proposed approach.     

Observer-based adaptive control of uncertain time-delay switched systems with stuck actuator faults

This paper concerns the observer-based adaptive control problem of uncertain time-delay switched systems with stuck actuator faults. Under the case where the original controller cannot stabilize the faulty system, multiple adaptive controllers are designed and a suitable switching logic is incorporated to ensure the closed-loop system stability and state tracking. New delay-independent sufficient conditions for asymptotic stability are obtained in terms of linear matrix inequalities based on piecewise Lyapunov stability theory. On the other hand, adaptive laws for on-line updating of some of the controller parameters are also designed to compensate the effect of stuck failures. Finally, simulation results for reference [1] model show that the design is feasible and efficient.     

一种高速延时无关片上异步转同步通信接口的设计

该文提出一种可用于多核片上系统和片上网络的快速延时无关异同步通信接口,由在独特运行协议下工作的环形FIFO实现,可在支持多种数据传输协议的前提下,保证数据从异步模块到同步时钟模块的完整高速传输。在0.18 m标准CMOS工艺下,传输接口的延时为792 ps,平均能耗为4.87 pJ/request,可满足多核片上系统和片上网络芯片高速低功耗、鲁棒性强和重用性好的设计要求。     

Fault detection and accommodation of a class of nonlinear systems with unknown multiple time-delayed faults

This paper investigates a fault detection and accommodation (FDA) problem of a class of nonlinear time-delay systems in the presence of unknown multiple time-delayed faults. Compared with existing literature, a main contribution of this paper is to design a time-delay independent FDA scheme, namely, the exact information on time delays is not required to implement the proposed FDA scheme. Under the assumption that the magnitude and occurrence time of multiple faults are unknown, we first design a delay-independent fault detection scheme with a detection threshold for time-delay systems and analyze the fault detectability. Then, an approximation-based fault accommodation design activated after the detection of the first fault is presented for compensating multiple faults. The robustness of the fault detection scheme and asymptotic stability of the tracking error are established through Lyapunov stability analysis. A simulation example is used to illustrate the proposed FDA scheme.     

H ∞ filtering of 2-D discrete state-delayed systems

In this paper, we deal with delay-independent and delay-dependent H _∞ filtering problems for a class of two-dimensional (2-D) discrete time-invariant systems with state delays. The 2-D systems are described by local state-space (LSS) Fornasini–Marchesini (FM) second model. First, delay-dependent bounded real lemma is proposed through introducing free weighting matrices. Then the delay-independent and delay-dependent H _∞ filtering designs are developed to assure the stability and H _∞ performance γ of filtering error systems via LMIs’ feasibility. Furthermore, the minimum H _∞ norm bound γ can be obtained by solving linear convex optimization problems. Numerical examples demonstrate the effectiveness and advantages of our results.

多时滞不确定网络控制系统的时滞独立稳定判据

针对一类多输入多输出（MIMO）网络控制系统．在考虑多重分布时滞和不确定性的情况下．建立了该系统的连续时闻数学模型．利用Lyapunov稳定性理论,结合线性矩阵不等式（LMI）方法和S-过程,给出了基于LMI形式的时滞独立渐近稳定判据．通过这些判据,能分析和判定具有多重时滞和不确定性的网络控制系统的时滞独立渐近稳定性．与已有的方法相比,该方法更加有效且求解方便．数值仿真结果表明了该方法的有效性．     

Easily testable necessary and sufficient algebraic criteria for delay-independent stability of a class of neutral differential systems

This paper analyzes the eigenvalue distribution of neutral differential systems and the corresponding difference systems, and establishes the relationship between the eigenvalue distribution and delay-independent stability of neutral differential systems. By using the “Complete Discrimination System for Polynomials”, easily testable necessary and sufficient algebraic criteria for delay-independent stability of a class of neutral differential systems are established. The algebraic criteria generalize and unify the relevant results in the literature. Moreover, the maximal delay bound guaranteeing stability can be determined if the systems are not delay-independent stable. Some numerical examples are provided to illustrate the effectiveness of our results.