一类非线性不确定性系统的H_∞鲁棒控制

对一类非线性不确定性系统二次稳定进行了分析 ,以 Ricatti不等式的方式 ,给出了这类不确定性系统二次稳定的充分必要条件 ,并讨论了这类系统的线性状态反馈控制器设计问题。通过一个简单的例子 ,说明了本文的方法正确、有效。

非线性不确定性时滞系统的鲁棒H_∞控制器设计

就一类具有范数有界的非线性不确定性的线性时滞系统，研究了其鲁棒Ｈ∞控制．利用文中所 考虑的非线性不确定性可用线性不确定性来等价表示，我们提出了一种鲁棒Ｈ∞控制器的设计方法，该 控制器不仅能鲁棒镇定原不确定系统，同时能保证闭环系统一定的Ｈ∞性能。

神经模糊控制在非线性时滞不确定性系统中的应用研究

针对时滞不确定非线性系统的控制问题 ,讨论了一种基于史密斯预估补偿控制结构的模糊控制与人工神经网络相结合的自优化控制方法。仿真分析表明它对时滞非线性时变对象具有良好的控制效果。

一类不确定性非线性系统的状态反馈鲁棒自适应控制器的设计与分析

该文考虑一类具有一般不确定性和部分参数未知的非线性系统 ( 1 ) ,设计出一种用于跟踪参考信号的状态反馈鲁棒自适应控制器 ,此控制器对系统参数和状态的不确定性具有鲁棒性 ,能保证闭环系统的全局稳定性 ,并解决了 ε-跟踪问题 .仿真结果表明 ,所设计的鲁棒自适应控制系统具有良好的跟踪性能 。

一类不确定性拟单边Lipschitz非线性系统观测器设计

本文研究了一类不确定性拟单边Lipschitz非线性系统观测器设计问题.利用拟单边Lipschitz条件代替通常的Lipschitz条件,得到了这类不确定性非线性系统观测器设计的线性矩阵不等式判据.结果推广了该类系统鲁棒H∞观测器问题.文末,给出了几个仿真算例以验证所给方法的正确性.

一类不确定非线性系统的鲁棒自适应控制

针对一类具有一般不确定性和未知参数的非线性系统 ,设计出一种适用于输出跟踪的鲁棒自适应控制器 .该控制器对系统的参数和状态的不确定性具有鲁棒性 ,能保证闭环系统的全局稳定性 ,并解决了 ε-跟踪问题 .仿真实例表明 。

非匹配不确定非线性系统的反演变结构控制

讨论一类非匹配不确定的非线性系统的输出跟踪问题。结合反演 ( Backstepping)设计方法和变结构控制 ,提出了反演变结构控制策略。对存在非匹配不确定性和未知干扰的系统 ,设计的反演变结构控制器实现鲁棒输出跟踪 ,闭环系统在有限时间进入滑动模态。

一类多输入不确定非线性系统的镇定

运用非线性系统的精确线性化方法和Ｌｉｅ代数工具，将一类满足一定条件的多输入不确定仿射型非线性系统交换成含可变参数的多变量线性系统。然后通过应用Ｒｏｕｔｈ算术求得合理的状态反馈矩阵，使得不确定向量在给定范围内任意变化时变参数闭环线性系统的特征多项式恒为Ｈｕｒｗｉｔｚ多项式，从而使该线性系统稳定。与此同时，间接地解决了原多输入不确定非线性系统的镇定问题，并且求得了镇定控制律的解析表达形式。给出了一个设计例子，其数值仿真的结果验证了本文所提出方法的正确性和有效性。

不确定非线性时延系统的模糊鲁棒H_2保值控制

针对一类不确定非线性时延系统,提出了一种H2模糊保值控制方法,采用模糊T-S模型对非线性时延系统建模,其中建模误差有上界约束,符合工程意义。利用李雅普诺夫稳定性理论,控制方案在闭环系统渐近稳定的条件下保证期望的H2最优性能。最后,混沌系统的仿真实验表明了该方法的可行性。

ROBUST STABILIZATING FOR A OLASS OF UNOERTAIN NONLINEAR INTEROONNECTED SYSTEMS USING VARIABLE STRUCTURE CONTROL

The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (VSC),two-level and decentralized variable structure control laws for this kind of systems are presented respectively,which achieve asymptotically stabilization despite the uncertainties and disturbances. At last,sirnulation of the disturbed two-pendulum system is given to illustrate the feasibility of proposed technique.

Non-fragile delay-dependent H_∞ control of linear time-delay system with uncertainties in state and control input

The problem of designing a non-fragile delay-dependent H∞ state-feedback controller was investigated for a linear time-delay system with uncertainties in state and control input. First, a recently derived integral inequality method and Lyapunov-Krasovskii stability theory were used to derive new delay-dependent bounded real lemmas for a non-fragile state-feedback controller containing additive or multiplicative uncertainties. They ensure that the closed-loop system is internally stable and has a given H∞ disturbance attenuation level. Then, methods of designing a non-fragile H∞ state feedback controller were presented. No parameters need to be tuned and can be easily determined by solving linear matrix inequalities. Finally, the validity of the proposed methods was demonstrated by a numerical example with the asymptotically stable curves of system state and controller output under the initial condition of x(0)=1 0 -1]T and h=0.8 time-delay boundary.

Design for robust stabilization of nonlinear systems with uncertain parameters

Based on Lyapunov stability theory, a design method for the robust stabilization problem of a class of nonlinear systems with uncertain parameters is presented. The design procedure is divided into two steps: the first is to design controllers for the nominal system and make the system asymptotically stabi1ize at the expected equilibrium point; the second is to construct closed-loop nominal system based on the first step, then design robust controller to make the error of state between the origina1 system and the nominal system converge to zero, thereby a dynamic controller with the constructed closed-loop nominal system served as interior dynamic is obtained. A numerical simulation verifies the correctness of the design method.

Sliding mode identifier for parameter uncertain nonlinear dynamic systems with nonlinear input

This paper presents a sliding mode (SM) based identifier to deal with the parameter identification problem for a class of parameter uncertain nonlinear dynamic systems with input nonlinearity. A sliding mode controller (SMC) is used to ensure the global reaching condition of the sliding mode for the nonlinear system; an identifier is designed to identify the uncertain parameter of the nonlinear system. A numerical example is studied to show the feasibility of the SM controller and the asymptotical convergence of the identifier.

ROBUST OBSERVER DESIGN FOR A CLASS OF UNCERTAIN NONLINEAR LARGE SCALE SYSTEMS *

In this paper, a mathematic description of a class of uncertain nonlinear large scale systems based on some practical application is given. A designing method to construct observers for such kind of nonlinear composite systems is developed. The unknown parameters and disturbances are assumed to be neither linear nor matched. A numerical example is used to illustrate the efficiency of our results.

The Robust Stabilizing Feedback for a Class of Nonlinear Uncertain Neutral Systems with Multiple Time Delays

The stabilization of a class of neutral systems with multiple time-delays is considered. To stabilize the neutral system with nonlinear uncertainty, a state feedback control law via compound memory and memoryless feedback is derived, by constructed Lyapunov functional, delay-independent stability criteria are proposed that are sufficient to ensure a uniform asymptotic stability property. Finally, two concise examples are provided to illustrate the feasibility of our results.

L_1 adaptive controller of nonlinear reference system in presence of unmatched uncertainties

An extension of L_1 adaptive control is proposed for the unmatched uncertain nonlinear system with the nonlinear reference system that defines the performance specifications. The control law adapts fast and tracks the reference system with the guaranteed robustness and transient performance in the presence of unmatched uncertainties. The interval analysis is used to build the quasi-linear parameter-varying model of unmatched nonlinear system, and the robust stability of the proposed controller is addressed by sum of squares programming. The transient performance analysis shows that within the limit of hardware a large adaption gain can improve the asymptotic tracking performance. Simulation results are provided to demonstrate the theoretical findings of the proposed controller.

A NOTE ON NONLINEAR ROBUST H_∞ ALMOST DISTURBANCE DECOUPLING PROBLEM WITH STABILITY

For a class of SISO nonlinear control systems with parameter uncertainty an almost disturbance decoupling problem with stability is defined and investigated. Back stepping technique provides a practical design method of controller, under which the $L2$ gain from the disturbance to the controlled output can be arbitrarily small subject to nonlinear uncertainties and the close-loop system is internally asymptotically stable.

ROBUST ATTITUDE CONTROL OF A 3DOF HELICOPTER WITH MULTI-OPERATION POINTS

A 3DOF (three degrees of freedom) helicopter attitude control system with multi-operationpoints is described as a MIMO time-varying uncertain nonlinear system with unknown constant param-eters,bounded disturbance and nonlinear uncertainty,and a robust output feedback control methodbased on signal compensation is proposed.A controller designed by this method consists of a nominalcontroller and a robust compensator.The controller is linear time-invariant and can be realized easily.Robust attitude tracking property of closed-loop system is proven and experimental results show thatthe designed control system can guarantee high precision robust attitude control under multi-operationpoints.

A study of parameter uncertainties causing uncertainties in modeling a grassland ecosystem using the conditional nonlinear optimal perturbation method

In this paper, we apply the approach of conditional nonlinear optimal perturbation related to the parameter(CNOP-P)to study parameter uncertainties that lead to the stability(maintenance or degradation) of a grassland ecosystem. The maintenance of the grassland ecosystem refers to the unchanged or increased quantity of living biomass and wilted biomass in the ecosystem,and the degradation of the grassland ecosystem refers to the reduction in the quantity of living biomass and wilted biomass or its transformation into a desert ecosystem. Based on a theoretical five-variable grassland ecosystem model, 32 physical model parameters are selected for numerical experiments. Two types of parameter uncertainties could be obtained. The first type of parameter uncertainty is the linear combination of each parameter uncertainty that is computed using the CNOP-P method. The second type is the parameter uncertainty from multi-parameter optimization using the CNOP-P method. The results show that for the 32 model parameters, at a given optimization time and with greater parameter uncertainty, the patterns of the two types of parameter uncertainties are different. The different patterns represent physical processes of soil wetness. This implies that the variations in soil wetness(surface layer and root zone) are the primary reasons for uncertainty in the maintenance or degradation of grassland ecosystems, especially for the soil moisture of the surface layer. The above results show that the CNOP-P method is a useful tool for discussing the abovementioned problems.

OUTPUT-FEEDBACK CONTROL FOR NONHOLONOMIC SYSTEMS WITH LINEAR GROWTH CONDITION

This paper deals with the stabilization of the nonholonomic systems with strongly nonlinear uncertainties. The objective is to design an output feedback law such that the closed-loop system is globally asymptotically regulated at the origin. The systematic strategy combines the input-state scaling technique with the backstepping technique. A novel switching control strategy based on the output measurement of the first subsystem is employed to make the subsystem far away from the origin. The simulation demonstrates the effectiveness of the proposed controller.