磁浮列车悬浮系统的神经网络建模研究

磁浮列车的悬浮系统是一个典型的非线性系统，其精确数学模型的建立非常困难。目前使用的系统模型大多是经过简化的近似线性化动力学模型，这样的模型在悬浮系统的研究中只起到方向上的指导作用，在工程实践中获取控制对象的精确模型具有重要的意义。神经网络不仅能够逼近复杂的非线性静态映射关系，同时也可以用于动态系统的特性学习，这里采用神经网络来建立悬浮系统的精确模型。文中简述了磁浮列车悬浮系统的基本结构和原理。讨论了非线性动态系统神经网络建模的一般方法。采用了输出反馈型的多层前向神经网络对悬浮系统进行了建模。并使用悬浮系统的输入输出数据对神经网络模型进行了训练和仿真，验证了该建模方法的可行性。     

pH中和系统辨识中的人工神经网络应用

pH中和作为化工、生物、发电和污水处理中的一个重要过程,具有极强的非线性和不确定性,很难对其进行精确建模,因此,pH值的控制一直是工业过程控制中的一个难题。本文借鉴了计算机领域中神经网络(NN)在非线性系统建模中的显著作用,结合对pH中和过程机理的分析,建立了基于BP神经网络的辨识模型,对典型的pH中和过程系统辨识进行了仿真研究,并进行了相关试验。试验结果表明:神经网络在pH中和过程辨识中具有较高的辨识精度,有着广阔的应用前景。     

基于补偿模糊神经网络的系统建模

本文介绍了补偿模糊神经网络原理 ,并利用它对非线性系统进行建模。通过MATLAB语言编制程序进行仿真试验 ,结果表明补偿模糊神经网络对于复杂系统的建模效果非常好。     

有色噪声中非线性动态系统的BP网络辨识

前馈多层神经网络为复杂的非线性系统提供了一种极具吸引力的模型结构。本文不利用仅含一个隐层的前馈多层神经网络来拟合离散时间非线性动态系统的问题进行了探讨。由于有色噪声的存在会导致网络模型偏差产生，文中引入了一种对噪声建模的方案。借助于非线性模型检验技术，本文给出了在有色噪声存在的情况下，利用ＢＰ网络辨识离散时间非线性动态系统的一般方法，仿真结果亦表明该方法行之有效。     

基于遗传算法的动态神经网络的建模与应用

本文分析了改进的ELMAN网络的结构，并讨论了神经网络的学习算法，针对BP算法的缺陷，提出了用遗传算法修正网络权值的学习算法。另外，将采用遗传算法进行训练的改进ELMAN网络应用于非线性系统的辨识和建模。通过仿真和在汽车磷化加热系统建模中的应用进一步说明了该方法用于高阶次非线性系统建模的可行性。     

化工过程建模中的一类复合型模糊神经网络

针对化工非线性过程建模问题,本文提出了一类由函数逼近和规则推理网络构成的复合型模糊神经网络,其规则网络基于过程先验知识用于对操作区间的划分,而函数网络采用改进型模糊神经网络结构完成非线性函数逼近。该技术已成功地用于某工业尿素ＣＯ２汽提塔液位建模。     

非线性系统神经网络预测控制研究进展

摘 要：神经网络由于其在非线性系统建模与优化求解方面的优势,被广泛应用于预测控制中,形成了各种各样的神经网络预测控制算法。本文系统地评述了非线性系统神经网络预测控制系统中的模型选取、控制器优化、控制系统结构设计方法以及收敛性理论等研究现状,分析了非线性系统神经网络预测控制算法存在的问题和今后的研究方向。     

基于ANFIS的非线性系统辨识研究

系统辨识是控制系统设计的基础，对非线性系统进行辨识是当前的难点；文献[1]提出了用模糊建模方法，文献[2]提出了用神经网络方法，在总结上述方法不足的基础上，该文提出了用自适应神经模糊推理系统(ANFIS)对非线性系统进行辨识的方法，仿真结果表明，ANFIS进行非线性系统辨识是可行的，其辨识精度很高。     

基于ANN逆模型补偿的复合控制系统仿真

为对复杂非线性系统进行辨识建模和实施有效控制,分析了基于神经网络的非线性系统逆模型的辨识和控制原理,研究了基于神经网络的非线性系统逆模型补偿的复合控制方法。基于复合控制思想,时常规PID控制器＋前馈神经网络逆模型补偿的复合控制结构方案进行了仿真。仿真结果表明,基于神经网络的非线性系统逆模型补偿的复合控制结构方案是有效的、相对简单的网络结构,可提高逆模型的泛化能力和非线性系统的控制精度。     

基于小波神经网络的非线性误差校正模型及其预测

针对非线性系统的预测问题，在线性和非线性协整理论涵义的基础上，提出利用小波神经网络进行非线性协整系统的非线性误差校正模型的研究，并给出该模型的建模方法．对沪深股市进行实证研究，与线性向量自回归模型进行比较．研究证明，小波神经网络所建立的非线性误差校正模型有较好的预测效果，能够有效地预测非线性经济系统．     

Intelligent non-linear modelling of an industrial winding process using recurrent local linear neuro-fuzzy networks

This study deals with the neuro-fuzzy (NF) modelling of a real industrial winding process in which the acquired NF model can be exploited to improve control performance and achieve a robust fault-tolerant system. A new simulator model is proposed for a winding process using non-linear identification based on a recurrent local linear neuro-fuzzy (RLLNF) network trained by local linear model tree (LOLIMOT), which is an incremental tree-based learning algorithm. The proposed NF models are compared with other known intelligent identifiers, namely multilayer perceptron (MLP) and radial basis function (RBF). Comparison of our proposed non-linear models and associated models obtained through the least square error (LSE) technique (the optimal modelling method for linear systems) confirms that the winding process is a non-linear system. Experimental results show the effectiveness of our proposed NF modelling approach.     

基于改进的PRPE算法的神经网络建模

本文改进了多层神经网络的并行递推预报误差（ＰＲＰＥ）算法，极大提高了算法的运行速度。并采用此算法对一非线性多变量耦合的电加热炉的工业实际对象，建立了对象的动态离散神经网络模型，取得了满意的模型拟合效果。     

A new adaptive multiple modelling approach for non-linear and non-stationary systems

This paper proposes a novel adaptive multiple modelling algorithm for non-linear and non-stationary systems. This simple modelling paradigm comprises K candidate sub-models which are all linear. With data available in an online fashion, the performance of all candidate sub-models are monitored based on the most recent data window, and M best sub-models are selected from the K candidates. The weight coefficients of the selected sub-model are adapted via the recursive least square (RLS) algorithm, while the coefficients of the remaining sub-models are unchanged. These M model predictions are then optimally combined to produce the multi-model output. We propose to minimise the mean square error based on a recent data window, and apply the sum to one constraint to the combination parameters, leading to a closed-form solution, so that maximal computational efficiency can be achieved. In addition, at each time step, the model prediction is chosen from either the resultant multiple model or the best sub-model, whichever is the best. Simulation results are given in comparison with some typical alternatives, including the linear RLS algorithm and a number of online non-linear approaches, in terms of modelling performance and time consumption.     

Intelligent non-linear modelling of an industrial winding process using recurrent local linear neuro-fuzzy networks

This study deals with the neuro-fuzzy (NF) modelling of a real industrial winding process in which the acquired NF model can be exploited to improve control performance and achieve a robust fault-tolerant system. A new simulator model is proposed for a winding process using non-linear identification based on a recurrent local linear neuro-fuzzy (RLLNF) network trained by local linear model tree (LOLIMOT), which is an incremental tree-based learning algorithm. The proposed NF models are compared with other known intelligent identifiers, namely multilayer perceptron (MLP) and radial basis function (RBF). Comparison of our proposed non-linear models and associated models obtained through the least square error (LSE) technique (the optimal modelling method for linear systems) confirms that the winding process is a non-linear system. Experimental results show the effectiveness of our proposed NF modelling approach.     

一种制动机气缸压力控制方法

为实现对具有非线性、时变和滞后等特性的机车制动系统的制动气缸的精确控制,提出一种气缸压力控制方法;该方法利用模糊控制领域的T-S模糊建模方法对容积室压力控制进行精确建模,通过BP算法学习得到系统的参数,利用模糊C平均聚类方法初始化模型的前件参数,采用带遗忘因子的递推最小二乘法在线修正模型的后件参数;得到系统精确的模型后再运用预测控制领域中基于模型的广义预测控制算法,实现对制动机气缸压力的精确控制;实际应用结果表明,该方法具有控制响应速度快、超调量小、自适应能力强、控制稳定等优点。     

Neural model input selection for a MIMO chemical process

In modelling non-linear systems using neural networks (NN), a commonly used method for the selection of network inputs, or to determine system order and time-delay, is to try different combinations of the system input–output data and choose the best one, giving minimum prediction error. The method is increasingly difficult to apply to industrial systems, due to their multivariable nature and complexity. A systematic method for the selection of model order and time-delay is developed in this paper, and applied to the neural modelling of a multivariable chemical process rig. The method is much simpler compared to the structure identification of the Non-linear Auto-Regressive with eXogenous inputs model (NARX), since the latter also needs to determine the significant terms from a linear-in-parameters polynomial. The orders and delays for system input and output are determined by identifying linearised models of the system. The method can also be applied to other approximations of a MIMO non-linear system, such as fuzzy logic models, etc. The application example demonstrates the selection procedure. Finally, the process rig is modelled using NNs according to the chosen structure, and the modelling error is compared with that of models with different structures to show the effectiveness of the method.     

Neural network for system identification

A double-hidden layer neural network is proposed to identify a non-linear dynamic system. The structure of this neural network is derived from the Kolmogorov theorem. Each node of the network corresponds to an unknown non-linear function to be estimated. An elementary function is designed to be a constituent of an arbitrary continuous function. The difficulty of function estimation is solved by estimating the weightings of the elementary functions. Two algorithms are applied to estimate the network weightings. The weightings of the upper hidden layer are estimated by the least squares method. On the other hand, the recursive prediction error algorithm is applied to estimate the parameters of the lower hidden layer. The simulation studies show that the proposed neural network can model the dynamics of a general non-linear system.     

Gaussian sum approximation for non-linear fixed-point prediction

Fixed-point prediction is the estimation of the state of a system at a future fixed time based on a noisy measurement with sequence length that increases with current time. A recursive algorithm for generating fixed-point prediction is given using the integrated form of the chain rule. For non-linear systems no general filter solution exists ; thus a gaussian sum approximation is developed. The method provides a numerical approximation for the time-dependant a posteriori density from which a filter can be generated.     

基于输出误差模型优化的甲板运动预报算法研究

本文提出了一种适用于多种复杂海况的大型舰船甲板运动预报方法,目的在于提高算法对不同海域复杂海况的适用性,以及对甲板运动模型的辨识精度与预报精度。该方法通过将量测数据的时间滞后处理引入输出误差模型来描述甲板运动的动力学模型,引入定阶准则确定了模型最优阶数数对。在此基础上应用了辅助模型递推最小二乘算法进行系统参数辨识并估计输出误差模型中的状态变量。实验结果表明,本文所提出的预报方法在系统参数辨识阶段可以将递推最小二乘算法的辨识精度提高5.13%,并且在预报阶段可以有效地将甲板运动的幅值与相位预测精度提高3.17%。该方法在复杂海况下具备良好的预测性能,适用于大型舰船甲板运动预报。     

INS algorithm using quaternion model for low cost IMU

This paper presents a generic inertial navigation system (INS) error propagation model that does not rely on small misalignment angles assumption. The modelling uses quaternions in the computer frame approach. Based on this model, an INS algorithm is developed for low cost inertial measurement unit (IMU) to solve the initial attitudes uncertainty using in-motion alignment. The distribution approximation filter (DAF) is used to implement the non-linear data fusion algorithm.