一类非线性微分代数子系统的逆系统控制及应用

对于指数1且关联可测的非线性微分-代数子系统,研究其逆系统控制方法,并将结果应用于电力系统元件分散控制.首先描述了此类非线性微分-代数子系统的物理背景和系统特性,并给出了非线性微分-代数子系统的α阶积分右逆系统和可逆的定义;然后给出了一种递归算法,以此来判别被控系统的可逆性,并构造出由状态反馈和动态补偿实现的α阶积分右逆系统,实现了复合系统的线性化解耦;最后针对多机电力系统中的一台同步发电机,应用所提出的方法研究其励磁控制电压问题.仿真结果验证了所提出方法的有效性.     

同步发电机非线性广义子系统模型的解耦控制

针对基于非线性奇异子系统模型的同步发电机,本文利用逆系统方法,研究了其励磁汽门综合控制的输入输出线性化解耦问题.同步发电机本质上是电力大系统中的一个非线性奇异子系统,同步发电机的解耦控制是使系统达到优良性能的重要途径之一.本文提出一种递推算法,利用逆系统方法将被控系统转化为两个独立的积分型线性子系统,实现了系统的动态解耦.仿真结果表明了本文所提控制方法的有效性.     

动物细胞悬浮培养过程神经网络逆解耦控制

动物细胞的悬浮培养以细胞增殖快、生产效率高等优势,成为动物细胞大规模培养的首选方式。而动物细胞悬浮培养过程是一个非线性、强耦合的多输入多输出系统,对一些生物参数(如细胞密度、基质浓度和产物浓度)的控制是提高整个生产水平的关键,应用神经网络逆系统方法对动物细胞悬浮培养过程进行线性化解耦控制,根据培养过程的特点,给出了相应的数学模型,并证明了系统的可逆性,利用神经网络的非线性逼近能力辨识出原系统的逆系统,然后串接在原系统前面构成伪线性复合系统,使动物细胞悬浮培养过程线性化解耦成三个子系统：一阶线性细胞密度子系统、一阶线性基质浓度子系统和一阶线性产物浓度子系统,最后设计模糊PID控制器对各解耦后的线性子系统进行控制,避免了传统PID控制器最优参数选取困难的问题。仿真结果表明,神经网络逆系统方法实现了对动物细胞悬浮培养过程的线性化解耦,系统对给定输入实现了高性能跟踪控制。     

神经网络广义逆系统控制

提出适合于高阶非线性系统线性化解耦的广义逆系统.它与被控系统复合后,不但能实现原系统的线性化和解耦,而且通过合理地设计逆系统,可使伪线性复合系统的极点在复平面上任意配置.进一步提出由静态神经网络和若干积分惯性等线性环节组成的神经网络广义逆系统,为模型未知且内部状态不易测量的高阶非线性系统的线性化解耦控制提供一条有效途径,进一步拓展了神经网络逆系统控制方法的适用范围.     

神经网络广义逆系统控制

提出适合于高阶非线性系统线性化解耦的广义逆系统，它与被控系统复合后，不但能实现原系统的线性化和解耦，而且通过合理地设计逆系统，可使伪线性复合系统的极点在复平面上任意配置，进一步提出由静态神经网络和若干积分惯性等线性环节组成的神经网络广义逆系统，为模型未知且内部状态不易测量的高阶非线性系统的线性化解耦控制提供一条有效途径，进一步拓展了神经网络逆系统控制方法的适用范围。     

基于支持向量机的非线性内模解耦控制

针对非线性内模控制在应用于多变量系统时逆模型难以建立的问题, 提出了支持向量机α阶逆系统的内模解耦控制方法. 该方法利用支持向量机辨识非线性系统的逆模型, 并将其串连在原系统之前, 运用逆系统方法的思想, 将一个多变量、非线性、强耦合的复杂系统通过反馈线性化解耦成多个相互独立的单输入单输出的伪线性复合子系统. 对求得的伪线性系统采用内模控制方法进行控制. 仿真试验表明该方法不需要系统精确的数学模型, 较一般的逆系统方法鲁棒稳定性好, 设计简单, 跟踪精度高, 是解决多变量非线性系统控制的一种可行的理论方法.     

并联混合有源滤波器逆系统解耦控制

针对并联混合有源滤波器(SHAPF)这一强耦合非线性系统的控制问题,提出了一种基于逆系统方法的SHAPF反馈线性化解耦控制策略.首先根据SHAPF非线性数学模型,采用逆系统方法生成其α阶积分逆系统,进而构造出解耦的伪线性系统,然后利用极点配置方法对伪线性系统进行综合,设计了系统的闭环控制器,并给出了系统零动态的镇定条件,保证了闭环控制系统的稳定性.最后仿真实验表明该控制策略能够有效消除电网中的谐波电流,并且与传统线性反馈-前馈控制策略相比,该控制策略具有更好的动静态性能.     

非线性MIMO系统线性化解耦的一种新方法：连续时间系统

给出用神经网络（ＮＮ）α阶积分逆系统实现连续非线性ＭＩＭＯ系统线性化解耦的方法。ＮＮα阶积分逆系统由一个静态神经网络加若干积分器构成,将其串联在原系统之前,原系统则解耦成若干个相互无关的ＳＩＳＯ伪线性积分系统。理论分析与仿真结果表明,对于精确模型未知的较一般的非线性ＭＩＭＯ系统,所给出的方法均能实现有效的线性化解耦,且结构简单,易于工程实现。     

非线性MIMO系统线性化解耦的一种新方法(Ⅰ)——连续时间系统

给出用神经网络（ Ｎ Ｎ）α阶积分逆系统实现连续非线性 Ｍ Ｉ Ｍ Ｏ 系统线性化解耦的方法。 Ｎ Ｎα阶积分逆系统由一个静态神经网络加若干积分器构成,将其串联在原系统之前,原系统则解耦成若干个相互无关的 Ｓ Ｉ Ｓ Ｏ 伪线性积分系统。理论分析与仿真结果表明,对于精确模型未知的较一般的非线性 Ｍ Ｉ Ｍ Ｏ 系统,所给出的方法均能实现有效的线性化解耦,且结构简单,易于工程实现。     

非线性MIMO系统线性化解耦的一种新方法（Ⅱ）——离散时间系统

研究如何构造神经网络（ＮＮ）α阶时延逆系统,并将其用于ＭＩＭＯ强耦合非线性离散时间系统的线性化解耦、ＮＮα阶时延逆系统由单个静态神经网络和若干时延因子组成,将其与原系统复合可形成具有最小阶时延的伪线性解耦系统。该方法对被控系统数学模型的先验知识要求很少,不但能有效地实现对原系统的线性化解耦,且结构简单,易于工程实现。     

陈述式基于方程仿真模型的约简

为解决复杂多领域连续系统的高效仿真问题,研究了陈述式基于方程仿真模型的约简策略.基于符号处理技术,提出了一种模型约简方法.该方法从方程的规范转换入手,通过消除特定形式方程缩减系统规模,将整个方程系统规划分解为一个可顺序求解的子系统序列.给出的实例表明文中约简方法效果显著.文中策略与算法已在多领域物理系统混合建模与仿真平台EMWorks中实现.     

Reduction of stable differential–algebraic equation systems via projections and system identification

Most large-scale process models derived from first principles are represented by nonlinear differential–algebraic equation (DAE) systems. Since such models are often computationally too expensive for real-time control, techniques for model reduction of these systems need to be investigated. However, models of DAE type have received little attention in the literature on nonlinear model reduction. In order to address this, a new technique for reducing nonlinear DAE systems is presented in this work. This method reduces the order of the differential equations as well as the number and complexity of the algebraic equations. Additionally, the algebraic equations of the resulting system can be replaced by an explicit expression for the algebraic variables such as a feedforward neural network. This last property is important insofar as the reduced model does not require a DAE solver for its solution but system trajectories can instead be computed with regular ODE solvers. This technique is illustrated with a case study where responses of several different reduced-order models of a distillation column with 32 differential equations and 32 algebraic equations are compared.     

Model-order reduction for differential-algebraic equation systems with higher index

In this paper, a new model-order reduction (MOR) approach is presented for reducing large-scale differential-algebraic equation (DAE) systems with higher index. This approach is based upon the balanced truncation, single-point, and multi-point MOR methods. We decompose the DAE system into an ordinary differential equation (ODE) subsystem and a DAE subsystem. The DAE subsystem has the same index as the original DAE system. Then, the balanced truncation method is applied to the ODE subsystem. Both single-point and multi-point methods are used to reduce the DAE subsystem. In generally, the multi-point method can perform better than the single-point method across a wide-range of frequencies. Some numerical examples demonstrate the effectiveness of our approach.     

Set membership inversion and robust control from data of nonlinear systems

A set membership method for right inversion of nonlinear systems from data is proposed in the paper. Both the cases where the system to invert is known or unknown and therefore identified from data are addressed. The method does not require the invertibility of the regression function describing the system and ensures tight bounds on the inversion error. In the case of unknown system, the method allows the derivation of a robust right‐inverse, guaranteeing the inversion error bound for all the systems belonging to the uncertainty set which can be defined from the available prior and experimental information. Based on such a set membership inversion, two methods for robust control of nonlinear systems from data are introduced: nonlinear feed‐forward control (NFFC) and nonlinear internal model control (NIMC). Both the design methods ensure robust stability and bounded tracking errors for all the systems belonging to the involved uncertainty set. Two applicative examples of robust control from data are presented: NFFC control of semi‐active suspension systems and NIMC control of vehicle lateral dynamics.Copyright © 2013 John Wiley & Sons, Ltd.     

Robust nonlinear control of spacecraft formation flying using constraint forces

A robust nonlinear control method is presented for spacecraft precise formation flying.With the constraint forces and consid-ering nonlinearity and perturbations,the problem of the formation keeping is changed to the Lagrange systems with the holonomic constraints and the differential algebraic equations (DAE).The nonlinear control laws are developed by solving the DAE.Because the traditional numerical solving methods of DAE are very sensitive to the various errors and the resulting con-trol laws are not ro...     

Input/output‐to‐state stability for switched nonlinear systems with unstable subsystems

In this paper, a couple of sufficient conditions for input/output‐to‐state stability (IOSS) of switched nonlinear systems with non‐IOSS subsystems are derived by exploiting the multiple Lyapunov functions (MLFs) method. A state‐norm estimator–based small‐gain theorem is also established for switched interconnected nonlinear systems under some proper switching laws, where the small‐gain property of individual connected subsystems is not required in the whole state space instead only in some subregions of the state space. The state‐norm estimator for the switched system under study is explicitly designed via a constructive procedure by exploiting the MLFs method and the classical small‐gain technique. The presented results permit removal of a technical condition in existing literature, where all subsystems in switched systems are IOSS or some are IOSS. An illustrative example is also provided to illustrate the effectiveness of the theoretical results.     

Decentralized adaptive output-feedback stabilization for large-scale stochastic nonlinear systems

In this paper, the problem of decentralized adaptive output-feedback stabilization is investigated for large-scale stochastic nonlinear systems with three types of uncertainties, including parametric uncertainties, nonlinear uncertain interactions and stochastic inverse dynamics. Under the assumption that the inverse dynamics of the subsystems are stochastic input-to-state stable, an adaptive output-feedback controller is constructively designed by the backstepping method. It is shown that under some general conditions, the closed-loop system trajectories are bounded in probability and the outputs can be regulated into a small neighborhood of the origin in probability. In addition, the equilibrium of interest is globally stable in probability and the outputs can be regulated to the origin almost surely when the drift and diffusion vector fields vanish at the origin. The contributions of the work are characterized by the following novel features: (1) even for centralized single-input single-output systems, this paper presents a first result in stochastic, nonlinear, adaptive, output-feedback asymptotic stabilization; (2) the methodology previously developed for deterministic large-scale systems is generalized to stochastic ones. At the same time, novel small-gain conditions for small signals are identified in the setting of stochastic systems design; (3) both drift and diffusion vector fields are allowed to be dependent not only on the measurable outputs but some unmeasurable states; (4) parameter update laws are used to counteract the parametric uncertainty existing in both drift and diffusion vector fields, which may appear nonlinearly; (5) the concept of stochastic input-to-state stability and the method of changing supply functions are adapted, for the first time, to deal with stochastic and nonlinear inverse dynamics in the context of decentralized control.     

基于逆系统方法的感应电机调速控制系统

从一般非线性系统的相对阶定义出发分析了感应电机的可逆性,对感应电机变频调速系统应用逆系统方法,将这一多变量、非线性、强耦合的复杂对象解耦成转速与转子磁链两个二阶线性子系统,并运用线性系统理论对设计的闭环控制器进行控制。仿真结果表明系统具有良好的静态及动态性能。     

Adaptive fuzzy semi‐decentralized control for a class of large‐scale nonlinear systems with unknown interconnections

In this paper, a general method is developed to generate a stable adaptive fuzzy semi‐decentralized control for a class of large‐scale interconnected nonlinear systems with unknown nonlinear subsystems and unknown nonlinear interconnections. In the developed control algorithms, fuzzy logic systems, using fuzzy basis functions (FBF), are employed to approximate the unknown subsystems and interconnection functions without imposing any constraints or assumptions about the interconnections. The proposed controller consists of primary and auxiliary parts, where both direct and indirect adaptive approaches for the primary control part are aiming to maintain the closed‐loop stability, whereas the auxiliary control part is designed to attenuate the fuzzy approximation errors. By using Lyapunov stability method, the proposed semi‐decentralized adaptive fuzzy control system is proved to be globally stable, with converging tracking errors to a desired performance. Simulation examples are presented to illustrate the effectiveness of the proposed controller. Copyright © 2006 John Wiley & Sons, Ltd.