具有自适应内模的一类非线性系统输出调节问题

研究一类包含未知非线性项的非线性系统的鲁棒输出调节问题.此类非线性系统由一包含未知参数的线性中性稳定的外系统驱动.首先运用调节器方程组解和标准内模将输出调节问题转化为镇定问题,然后给出控制律镇定闭环系统,同时利用镇定输入项和外系统信息设计出自适应内模方程.控制律使得闭环系统的信号全局最终有界,且误差被调节至预先设定的任意小的精度值.仿真结果验证了所提出设计方法的有效性.

     

一类非线性输出反馈系统的自适应输出调节问题

本文讨论一类非线性系统的全局鲁棒输出调节问题.假定被控非线性系统的系统输入方向未知,且产生参考或扰动信号的外部系统含未知参数,这为控制律的设计带来了挑战.文章使用自适应控制方法和内模原理,解决了一类相对阶为1的非线性输出反馈系统的输出调节问题,并将结果应用于处理Lorenz系统的渐近跟踪问题.     

输出调节和内模原理

输出调节指的是控制系统的输出,以达到渐近跟踪给定的轨线或渐近抑制干扰的目的.对于线性系统,内模原理是解决这一问题的强有力的工具.在最近10年,非线性系统的输出调节问题及内模原理成为国际非线性控制研究的前沿课题.该文的目的是对此问题给一综述介绍.     

一类仿射非线性系统的自适应神经网络输出反馈变结构控制

本文研究了一类仿射非线性系统的输出反馈控制问题. 在介绍文献[4~6]的基础上, 提出一种基于神经网络参数化技术的自适应变结构输出反馈控制方案, 该方案能够避免使用严格正实(SPR)条件, 它不仅能够保证收缩条件的可行性, 而且还可以分析闭环系统的稳态和暂态的一致有界性, 并能够对观测增益和控制参数的选取进行清楚地分析.     

一类时滞非线性控制系统的输出调节

研究了一类单输出时滞线性系统的输出调节问题,首先通过精确线性化方法将其转化为一类特殊线性时滞系统对非线系统的跟踪总是,然后通过积分变换转化为无时滞的线性系统对非线性系统的跟踪,新的精确线性化结果保证了经过积分变换后的系统仍然可控,同时,提出了可解性的概念解决了线性系统对非线性系统的跟踪问题,得到了时滞非线性系统输出调节问题的局部和全局的结果,该结果对外部系统假设较弱。     

一类非线性系统鲁棒自适应控制器

反步设计法是针时不确定非线性系统的进行鲁棒自适应控制器设计的主要方法之一,它主要是靠递推来完成,方法简单,但存在过参数化问题.在反步设计法的基础上,通过引入调节函数,选取合适的虚拟控制律,设计一种鲁棒自适应控制器.然后,利用Lyapunov稳定性理论证明了该设计不仅能够克服过参数化的问题,而且能够保证所设计的系统具有鲁棒自适应稳定性.仿真实例证明了该方法的有效性.     

一类非线性系统鲁棒自适应控制器

反步设计法是针对不确定非线性系统的进行鲁棒自适应控制器设计的主要方法之一,它主要是靠递推来完成,方法简单,但存在过参数化问题。在反步设计法的基础上,通过引入调节函数,选取合适的虚拟控制律,设计一种鲁棒自适应控制器。然后,利用Lyapunov稳定性理论证明了该设计不仅能够克服过参数化的问题,而且能够保证所设计的系统具有鲁棒自适应稳定性。仿真实例证明了该方法的有效性。     

经输出动态反馈的非线性奇异系统输出调节问题

讨论非线性奇异系统的输出调节问题,在没有可正常化的假设条件下,给出了降阶的正常状态空间的输出动态反馈控制器的设计,并导出了这种控制器存在的充分必要条件.     

一类非线性控制系统的输出调节

对一类非线性控制系统的输出调节问题,首先通过推广的精确线性化方法,将其转化为一类特殊的受扰线性控制系统对非线性系统的跟踪问题,然后利用可解性的概念解决了该问题,得到了非线性系统输出调节问题的局部和全局的结果。     

基于神经网络的非线性系统的输出调节

非线性系统输出调节问题可解的充要条件是存在一个中心流形满足某个非线性偏微分方程。本文用多层前向神经网络求解该非线性偏微分方程，从而逼近非线性系统的中心流形。在此基础上，构造状态反馈控制律，实现非线性系统的输出调节。     

Output regulation of nonlinear output feedback systems with exponential parameter convergence

This paper revisits the global robust output regulation (GROR) problem of nonlinear output feedback systems with uncertain exosystems by error output feedback control. The problem was conventionally tackled by employing a linear canonical internal model and as a result, suitable adaptive stabilization has to be done for the augmented system to achieve output regulation. Distinguished from that, a novel nonlinear internal model approach is developed in the present study that successfully converts the GROR problem into a robust non-adaptive stabilization problem for the augmented system. The feature of the new approach is two-fold. On one hand, stabilization of augmented system is disentangled from any extra adaptive control law and thus the procedure is simplified. On the other hand, it leads to explicit strict Lyapunov characterization for the closed-loop system and consequently assures exponential parameter convergence.     

Global adaptive output regulation of a class of nonlinear systems with nonlinear exosystems

This paper deals with global output regulation with nonlinear exosystems for a class of uncertain nonlinear output feedback systems. The circle criterion is exploited for the internal model design to accommodate the nonlinearities in the exosystems, and the explicit conditions are given for the exosystems such that the proposed internal model design can be applied. The uncertainties of the output feedback systems are in the form of unknown constant parameters, and adaptive control techniques are used to ensure the global stability of the proposed control design for output regulation.     

Cooperative semi-global robust output regulation for a class of nonlinear uncertain multi-agent systems

In this paper, we study the cooperative semi-global robust output regulation problem for a class of minimum phase nonlinear uncertain multi-agent systems. This problem is a generalization of the leader-following tracking problem in the sense that it further addresses such issues as disturbance rejection, robustness with respect to parameter uncertainties. To solve this problem, we first introduce a type of distributed internal model that converts the cooperative semi-global robust output regulation problem into a cooperative semi-global robust stabilization problem of the so-called augmented system. We then solve the semi-global stabilization problem via distributed dynamic output control law by utilizing and combining a block semi-global backstepping technique, a simultaneous high gain feedback control technique, and a distributed high gain observer technique.     

Global stabilization and disturbance suppression of a class of nonlinear systems with uncertain internal model

This paper deals with global stabilization and disturbance suppression of a class of nonlinear systems using output feedback. The disturbances generated from a unknown linear exosystem are completely compensated. The order of the exosystem is assumed known and the eigenvalues are distinct. No other assumptions are needed in the control design. This means that the proposed control design is able to completely compensate the disturbances without knowing their amplitudes, frequencies and phases, as long as the number of different frequency components in the disturbances is known. A new formulation of state estimation is introduced to ensure the global stabilization and complete disturbance suppression. Adaptive control technique is used to design an adaptive internal model based on a recently introduced formulation of unknown exosystems and the parameters in the adaptive internal model converge to the actual values, from which the unknown disturbance frequencies can be calculated. In the proposed control design, a number of control coefficients are made adaptive so that the result is global with respect to unknown frequencies in the disturbances.     

Output regulation of nonlinear singularly perturbed systems based on T-S fuzzy model

1IntroductionNonlinear singularly perturbed systems arise in a widevariety of engineering applications,representative examplesinclude catalytic continuous stirred_tank reactors[1],biochemical reactors[2],fluidized catalytic crackers[3],flexible mechanical systems[4],electromechanical networks[5],etc.For such systems,the output regulation problem,i.e.the problem of having the output tracking reference(or rejecting disturbance)signals produced by someexternal generator,is ofimportance.In linear …     

Output regulation of nonlinear singularly perturbed systems based on T-S fuzzy model

Based on the T_S model,the output regulation of nonlinear singularly perturbed systems via state feedback is discussed.It is shown that,under standard assumptions,this problem is solvable if and only if certain linear matrix equations are solvable.Once these equations are solvable, the state feedback regulator can easily be constructed.     

Semi-global robust output regulation for a class of singular nonlinear systems via nonlinear internal model

Most of existing results on robust output regulation problem of singular nonlinear systems are limited to local solutions. In this paper, the semi-global robust output regulation problem for a class of singular nonlinear systems is investigated by using a nonlinear internal model. Attaching a nonlinear internal model to the singular nonlinear system yields an augmented singular nonlinear system whose semi-global robust stabilisation solution leads to the solution of the semi-global robust output regulation problem of the original singular nonlinear system. The solvability conditions of the semi-global output regulation problem are established by addressing the solvability of the robust stabilisation problem of augmented singular nonlinear system. Finally, a numerical simulation example is used to illustrate the design of the semi-global regulator for the singular nonlinear systems.     

Output regulation of nonlinear systems using conditional servocompensators

This paper studies the output regulation of nonlinear systems using conditional servocompensators. Previous work introduced the conditional servocompensator, which acts as a traditional servocompensator in the neighborhood of a zero-error manifold while acting as a stable system otherwise, leading to improvement in the transient response while achieving zero steady-state regulation error. The conditional servocompensator tool was introduced for sliding-mode feedback controllers. This paper extends the technique to more general feedback controllers by using Lyapunov redesign and saturated high-gain feedback.     

Input disturbance suppression for a class of feedforward uncertain nonlinear systems

This paper deals with the problem of asymptotically rejecting bounded unknown disturbances affecting the input channel of a feedforward uncertain nonlinear system. The problem is solved assuming that the matched disturbance belongs to the class of signals generated by an autonomous neutrally stable exosystem whose state is not accessible. We design an internal model-based regulator capable on one hand to reject the matched disturbance for any initial state of the exosystem and, on the other hand, to robustly globally asymptotically stabilize the system using state feedback.     

Parameter convergence and minimal internal model with an adaptive output regulation problem

The parameter convergence of nonlinear adaptive control systems is an important yet not well addressed issue. In this paper, using the global robust output regulation problem of output feedback systems with unknown exosystems as a platform, we will show that the well known persistency of excitation (PE) condition still guarantees the convergence of the estimated parameter vector to the true parameter vector. Moreover, the PE condition will be satisfied if the internal model is minimal in certain sense.