Stabilization of Euler-Bernoulli beam with a nonlinear locally distributed feedback control

This paper studies the stabilization problem of uniform Euler-Bernoulli beam with a nonlinear locally distributed feedback control. By virtue of nonlinear semigroup theory, energy-perturbed approach and polynomial multiplier skill, the authors show that, corresponding to the different values of the parameters involved in the nonlinear locally distributed feedback control, the energy of the beam under the proposed feedback decays exponentially or in negative power of time t as t → ∞.     

Neural network-based H∞ filtering for nonlinear systems with time-delays

A novel H∞ design methodology for a neural network-based nonlinear filtering scheme is addressed. Firstly, neural networks are employed to approximate the nonlinearities. Next, the nonlinear dynamic system is represented by the mode-dependent linear difference inclusion （LDI）. Finally, based on the LDI model, a neural network-based nonlinear filter （NNBNF） is developed to minimize the upper bound of H∞ gain index of the estimation error under some linear matrix inequality （LMI） constraints. Compared with the existing nonlinear filters, NNBNF is time-invariant and numerically tractable. The validity and applicability of the proposed approach are successfully demonstrated in an illustrative example.     

Nonconforming finite element method for nonlinear parabolic equations

<正> A nonconforming finite element method for the nonlinear parabolic equations is studied inthis paper.The convergence analysis is presented and the optimal error estimate in L~2(‖·‖_h)norm isobtained through Ritz projection technique,where ‖·‖_h is a norm over the finite element space.     

非线性系统的鲁棒容错控制

对非线性鲁棒容错控制的研究现状进行了综述。首先介绍了一些与非线性鲁棒容错控制密切相关的研究方向,包括非线性系统理论、鲁棒控制、自适应控制等。然后分被动式和主动式介绍了非线性系统鲁棒容错控制的研究现状;被动容错控制方面,主要介绍了可靠控制方法;主动容错控制通常需要解决三个问题:诊断、控制以及二者的综合,本文按照这个划分对主动式的研究现状进行了总结。最后,探讨了该领域的一些热点和难点问题。     

Constrained predictive control of nonlinear stochastic systems

The receding horizon control (RHC) problem is considered for nonlinear Markov jump systems which can be represented by Takagi-Sugeno fuzzy models subject to constraints both on control inputs and on observe outputs. In the given receding horizon, for each mode sequence of the T-S modeled nonlinear system with Markov jump parameter, the cost function is optimized by constraints on state trajectories, so that the optimization control input sequences are obtained in order to make the state into a terminal invariant set. Out of the receding horizon, the stability is guaranteed by searching a state feedback control law. Based on such stability analysis, a linear matrix inequality approach for designing receding horizon predictive controller for nonlinear systems subject to constraints both on the inputs and on the outputs is developed. The simulation shows the validity of this method.         

一类非线性系统的鲁棒无源性综合问题

针对一类带有界范数不确定性的仿射非线性系统,研究它的鲁棒无源性综舍问题.首先,基于非线性矩阵不等式方法得到系统是鲁棒无源的充分条件;然后在此基础上,获得存在状态反馈控制器使得该系统鲁棒无源控制问题可解的充分条件,并给出所需控制器的参数化表达.最后,简单阐述了利用凸优化方法通过求解一系列相应的线性矩阵不等式来得到非线性矩阵不等式局部解的思想.     

Testing linear and nonlinear granger causality in CSI300 futures and spot markets based on new concepts of nonlinear positive/negative spillover

supported by the National Natural Science Foundation of China under Grant Nos.71125005 70871108 and 70810107020;; Outstanding Talents Funds of Organization Department Beijing Committee of CPC     

基于状态相依RBF-ARX模型的非线性预测控制及应用

对于一类工作点时变的光滑非线性多变量系统,采用状态相依自回归(state-dependent auto-regressive with exogenous, SD-ARX)模型描述系统的非线性状态特征,用高斯径向基函数(radial basis function, RBF)神经网络近似SD-ARX模型的函数型系数,利用结构化非线性参数优化方法(structured nonlinear parameter optimization method, SNPOM)离线估计模型参数,并以状态信号量引导模型实时反映对象的动态特性,在此基础上设计的非线性预测控制器因避免了在线模型参数估计,可提高系统的实时性,并具有较好的控制效果。对四旋翼飞行器的实验结果验证了建模方法的有效性和控制方法的可行性。     

飞行器抗饱和鲁棒自适应非线性模型预测控制

针对巡航飞行器同时存在较大外部干扰和模型参数不确定性时自适应预测控制性能下降的问题,设计了带有模糊干扰观测器(fuzzy disturbance observer, FDO)补偿的鲁棒自适应非线性模型预测控制(robust adaptive nonlinear model predictive control, RANMPC)方法(简记为FDO-RANMPC方法)。首先,利用具有未知参数限制条件的递推最小二乘方法在线辨识模型参数;其次,利用模糊干扰观测器输出值抵消幅值较大的复合干扰,再利用Tube鲁棒预测控制策略设计了飞行器底层姿态系统具有稳定保障的FDO-RANMPC控制器;最后,在考虑复合不确定性情况下对指令姿态角跟踪的仿真中验证了控制器的有效性及其渐进稳定性。     

Properties of storage functions and applications to nonlinear stochastic <Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript> control

This paper discusses the properties of the storage functions for a class of nonlinear stochastic systems. Some necessary and sufficient conditions for a function to be a storage function are derived. As applications, the finite and infinite horizon nonlinear stochastic H _∞ controls for systems with state, control, and external disturbance dependent noise are investigated, which generalize the previous results.     

一类非线性系统的模糊变结构控制方案

针对一类特殊非线性系统的模糊变结构控制及稳定性问题,通过将非线性系统化为多个精确T S模型来建立非线性系统精确的T S模糊模型,将模糊理论与成熟的线性变结构控制理论相结合设计出一种模糊变结构控制器,提出了使全局模糊模型稳定的充分条件,并用Lyapunov稳定性理论证明该控制器能确保模糊动态模型全局渐近稳定,从而使非线性系统稳定。仿真结果表明了该设计方法的有效性。     

基于未知输入观测器方法的非线性切换系统故障检测

基于非线性未知输入观测器方法对一类离散时间非线性切换系统的故障检测问题进行了研究。给出了两种不同结构的非线性未知输入观测器。针对每一种观测器都考虑了两种切换信号:任意时间切换信号和满足平均驻留时间的切换信号。在任意切换信号下,使用了切换Lyapunov函数的方法来设计非线性未知输入观测器的参数;在满足平均驻留时间切换信号下,使用了多Lyapunov函数方法进行观测器参数的设计。然后利用已知的非线性未知输入观测器,得到残差生成器,进而实现故障检测。通过数值仿真例子,验证了故障检测方法的有效性。     

Sliding mode H∞ control for a class of uncertain nonlinear state-delayed systems

A new proportional-integral (PI) sliding surface is designed for a class of uncertain nonlinear state-delayed systems. Based on this, an adaptive sliding mode controller (ASMC) is synthesized, which guarantees the occurrence of sliding mode even when the system is undergoing parameter uncertainties and external disturbance. The resulting sliding mode has the same order as the original system, so that it becomes easy to solve the H_∞ control problem by designing a memoryless H_∞ state feedback controller. A delay-dependent sufficient condition is proposed in terms of linear matrix inequalities (LMIs), which guarantees the sliding mode robust asymptotically stable and has a noise attenuation level γ in an H_∞ sense. The admissible state feedback controller can be found by solving a sequential minimization problem subject to LMI constraints by applying the cone complementary linearization method. This design scheme combines the strong robustness of the sliding mode control with the H_∞ norm performance. A numerical example is given to illustrate the effectiveness of the proposed scheme.     

A nonlinear Krein Rutman theorem

A nonlinear version of Krein Rutman Theorem is established. This paper presents a unified proof of the Krein Rutman Theorem for linear operators and for nonlinear operators, and of the Perron-Frobenius theorem for nonnegative matrices and for nonnegative tensors.     

Backstepping tracking control for nonlinear time-delay systems

1. INTRODUCTION The presence of time delay has a significant effect on system performance and destroys the stability of closed-loop system[1]. Therefore, the study on time-delay systems has important practical significance. Recen- tly,considerable progress has been made in this field[1~10]. According to the dependency of the designed contr-oller depends on the time delay, the control approa-ches for time-delay systems can be classified into two categories: delay-dependent[2~3,10] and dela…     

Tracking controller for robot manipulators via composite nonlinear feedback law

A composite nonlinear feedback tracking controller for motion control of robot manipulators is de-scribed. The structure of the controller is composed of a composite nonlinear feedback law plus full robot nonlinear dynamics compensation. The stability is carried out in the presence of friction. The controller takes advantage of varying damping ratios induced by the composite nonlinear feedback control, so the transient performance of the closed-loop is remarkably improved. Simulation results demonstrate the feasibility of the proposed method.     

Improved filtered- adaptive inverse control and its application on nonlinear ship maneuvering

The drawbacks of common nonlinear Filtered- adaptive inverse control (AIC) method, such as the unreliability due to the change of delay time and the faultiness existing in its disturbance control loop, are discussed. Based on it, the diagram of AIC is amended to accommodate with the characteristic of nonlinear object with time delay. The corresponding Filtered- adaptive algorithm based on RTRL is presented to identify the parameters and design the controller. The simulation results on a nonlinear ship model of “The R.O.V Zeefakkel” show that compared with the previous scheme and adaptive PID control, the improved method not only keeps the same dynamic response performance, but also owns higher robustness and disturbance rejection ability, and it is suitable for the control of nonlinear objects which have higher requirement to the maneuverability under complex disturbance environment.     

Robust output-feedback stabilization of a class of nonlinear systems with the nonlinearities of varied form

1 .INTRODUCTIONThe problem of global stabilization of nonlinearsystems by output feedback has received much at-tention. Unlike in the case of linear systems ,theseparation principle generally does not hold fornonlinear systems . This is one of the reasons whythe problemis more difficult . As investigated byRef .[1] ,some extra growth conditions onthe un-measurable states of the systemare usually neces-sary for the global stabilization of nonlinear sys-tems via output feedback. For exampl…     

基于最优控制的系统时变非线性参数模糊辨识

针对运动状态下结构连接处的时变物理参数对研究结构动态特性与工程实际应用具有重要价值,提出了一种结构连接处时变非线性物理参数辨识方法。该方法利用每个子结构的动力学模型,将结构连接处的非线性恢复力作为模型的输入,利用最优控制理论与模糊数学的方法辨识出结构连接处的非线性恢复力,并应用子结构法计算出结构连接处的响应。最后利用最小二乘法拟合了非线性恢复力。计算出非线性恢复力的时变系数。仿真算例表明了该算法的有效性。     

TF/TA trajectory tracking using nonlinear predictive control approach

The use of a methodology of nonlinear continuous predictive control to design the guidance control law for the aircraft TF/TA² trajectory tracking problem is emplojed. For the derivation of the predictive control law, by using Taylor series expansion, and based on optimizing a performance index which is a quadratic function of both the predictive value of the state variables and the control inputs, a state variable feedback controller for nonlinear systems is obtained, and it provides a tradeoff between satisfactory tracking performance and the control magnitude requirements. Numerical simulation results for a supersonic fighter aircraft model show the viability of this approach.