NN adaptive pole placement method for sintering finish point control

A neural network model with a special structure, which is divided into linear and nonlinear parts, was proposed for identification of a nonlinear system. In this model, the nonlinear part of the object is treated as a measured disturbance, and is compensated by a feed forward method; an adaptive pole placement algorithm is used to control the linear part of the object. The simulation results show that the identification efficiency and accuracy are improved when the new controller is applied to sintering finish point control.     

An integrated scheme of neural network and optimal predictive control

An approach of adaptive predictive control with a new structure and a fast algorithm of neural network (NN) is proposed. NN modeling and optimal predictive control are combined to achieve both accuracy and good control performance. The output of nonlinear network model is adopted as a measured disturbance that is therefore weakened in predictive feed-forward control. Simulation and practical application show the effectiveness of control by the proposed approach.     

Neural network modeling and control of proton exchange membrane fuel cell

A neural network model and fuzzy neural network controller was designed to control the inner impedance of a proton exchange membrane fuel cell (PEMFC) stack. A radial basis function (RBF) neural network model was trained by the input-output data of impedance. A fuzzy neural network controller was designed to control the impedance response. The RBF neural network model was used to test the fuzzy neural network controller. The results show that the RBF model output can imitate actual output well, the maximal error is not beyond 20 m-, the training time is about 1 s by using 20 neurons, and the mean squared errors is 141.9 m-2. The impedance of the PEMFC stack is controlled within the optimum range when the load changes, and the adjustive time is about 3 min.     

Industrial applications of advanced control techniques

This paper discusses two industrial control applications using advanced control techniques. They are the optimal-tuning nonlinear PID control of hydraulic systems and the neural predictive control of combustor acoustic of gas turbines. For hydraulic control systems, an optimal PID controller with inverse of dead zone is introduced to overcome the dead zone and is designed to satisfy desired time-domain performance requirements. Using the adaptive model, an optimal-tuning PID control scheme is proposed to provide optimal PID parameters even in the case where the system dynamics is time variant. For combustor acoustic control of gas turbines, a neural predictive control strategy is presented, which consists of three parts: an output model, output predictor and feedback controller. The output model of the combustor acoustic is established using neural networks to predict the output and overcome the time delay of the system, which is often very large, compared with the sampling period. The output-feedback c     

Terminal Angular Constraint Integrated Guidance and Control for Flexible Hypersonic Vehicle with Dead-Zone Input Nonlinearity

This paper presents an integrated guidance and control model for a flexible hypersonic vehicle with terminal angular constraints. The integrated guidance and control model is bounded and the dead-zone input nonlinearity is considered in the system dynamics. The line of sight angle, line of sight angle rate, attack angle and pitch rate are involved in the integrated guidance and control system. The controller is designed with a backstepping method, in which a first order filter is employed to avoid the differential explosion. The full tuned radial basis function(RBF) neural network(NN) is used to approximate the system dynamics with robust item coping with the reconstruction errors, the exactitude model requirement is reduced in the controller design. In the last step of backstepping method design, the adaptive control with Nussbaum function is used for the unknown dynamics with a time-varying control gain function. The uniform ultimate boundedness stability of the control system is proved. The simulation results validate the effectiveness of the controller design.     

Angular velocity dynamics identification of small unmanned helicopter using fuzzy model

Attitude identification method for unmanned helicopter based on fuzzy model at hovering is presented.The dynamical attitude model is considered as basis for attitude control and it is very complex.To reduce the complexity of model,nonlinear model of unmanned helicopter with unknown parameters are to be determined by fuzzy system first and then derivative based gradient method is used to identify unknown parameters of model.Gradient method is used due to ability that fuzzy system is not necessarily to be linear in parameters,therefore all fuzzy sets for input and output can be adjusted.The validity of the proposed model was verified using experimental data obtained by the commercially available flight simulator X-Plane.The simulation results showed high accuracy of the modeling method and attitude dynamics data matched well with experimental data.     

LS-based discrete-time adaptive nonlinear control——Feasibility and limitations

Global stability and instability of a class of discrete-time adaptive nonlinear control systems are investigated.The systems to be controlled are assumed to be linear in unknown parameters but nonlinear in dynamics which are characterizEd by a nonlinear function f(x).It is shown that in the scalar parameter case,when the standard least-squares (LS) method is used in estimation,the certainty equivalence adaptive control is globally stable whenever f(x) has a growth rate |f(x)| =0(||x||b) with b<8.Moreover,in the case where b≥8,it is also shown that the dosed-loop adaptive control system does not have global stability in general.Both the results found and the new analytical methods introduced may be regarded as a basic step for further study of discrete-time adaptive nonlinear control systems.     

Control method on serial type pump-valve coordinated electro-hydraulic servo system

In order to compromise the conflicts between control accuracy and system efficiency of conventional electro-hydraulic servo systems, a novel pump-valve coordinated electro-hydraulic servo system was designed and a corresponding control strategy was proposed. The system was constituted of a pump-controlled part and a valve-controlled part, the pump controlled part is used to adjust the flow rate of oil source and the valve controlled part is used to complete the position tracking control of the hydraulic cylinder. Based on the system characteristics, a load flow grey prediction method was adopted in the pump controlled part to reduce the system overflow losses, and an adaptive robust control method was adopted in the valve controlled part to eliminate the effect of system nonlinearity and parametric uncertainties due to variable hydraulic parameters and system loads on the control precision. The experimental results validated that the adopted control strategy increased the system efficiency obviously with guaranteed high control accuracy.     

Adaptive high precision position control of servo actuator with friction compensation using LuGre model

Adaptive control of servo actuator with nonlinear friction compensation is addressed.LuGre dynamic friction model is adopted to characterize the nonlinear friction and a new kind of sliding-mode observer is designed to estimate the internal immeasurable state of LuGre model.Based on the estimated friction state,adaptive laws are designed to identify the unknown model parameters and the external disturbances,and the system stability and asymptotic trajectory tracking performance are guaranteed by Lyapunov function.The position tracking performance is verified by the experimental results.     

A five-fingered underactuated prosthetic hand： hardware and its control scheme

A five-fingered underactuated prosthetic hand controlled by surface EMG (electromyographic) signals is presented in this paper. The prosthetic hand was designed with simplicity, lightweight and dexterity on the requirement of anthropomorphic hands. Underactuated self-adaptive theory was adopted to decrease the number of motors and weight. The control part of the prosthetic hand was based on a surface EMG motion pattern classifier which combines LM-based (Levenberg-Marquardt) neural network with the parametric AR (autoregressive) model. This motion pattern classifier can successfully identify the flexions of the thumb, the index finger and the middle finger by measuring the surface EMG signals through two electrodes mounted on the flexor digitorum profundus and flexor pollicis longus. Furthermore, via continuously controlling a single finger's motion, the five-fingered underactuated prosthetic hand can achieve more prehensile postures such as power grasp, centralized grip, fingertip grasp, cylindrical grasp, etc. The experimental results show that the classifier has a great potential application to the control of bionic man-machine systems because of its fast learning speed, high recognition capability and strong robustness.     

一种非线性系统的鲁棒型预测控制算法

提出一种基于神经网络的鲁棒型广义预测控制(GPC)方法,该方法首先用神经网络对非线性系统进行辨识,然后在控制中将模型输出值与测量输出值进行综合,代替量测输出用于控制中,从而降低辨识器与控制器对未建模动态的敏感性,增强控制器的适应能力和鲁棒性.仿真结果表明:将本方法应用于非线性系统控制,对未建模动态具有较强的鲁棒性和控制能力.     

预测模型的单神经元PI控制器

针对工业过程和实际控制对象的慢时变非线性的特点 ,设计了一种预测模型的单神经元 PI控制器。采用单神经元 PI控制算法与神经网络预测模型相结合的控制策略 ,用 PI控制规律来确定控制器的输出。用一个自适应神经元网络作为非线性系统的预测模型 ,估计下一步的输出值 ;用一个单神经元实现 PI控制来优化下一步的控制。利用 Matlab/Sim ulink工具对 PI控制器和预测模型的单神经元 PI控制器进行比较仿真实验 ,其控制对象为典型的非线性系统。仿真实验表明 :预测模型的单神经元 PI控制器具有结构简单 ,计算速度快 ,鲁棒性好等特点     

一类基于对象正向模型的神经网络自适应控制器的设计

提出了一种基于对象正向模型的神经网络自适应控制器 ,该方法只须辨识对象的正向模型 ,将神经网络与优化方法相结合 ,对控制量进行优化迭代求解。仿真结果表明 ,该算法能精确跟踪设定输出 ,响应速度快 ,超调量小 ,无稳定误差 ,控制效果好     

非匹配不确定非线性系统的鲁棒输出跟踪

针对一类非匹配不确定非线性系统,提出一种鲁棒自适应渐近输出跟踪控制方法,该方法无须已知不确定性函数及其各阶导数上界。基于Lyapunov函数方法,给出了鲁棒自适应控制律以及GCMAC神经网络权值调整算法,通过后一个状态镇定前一个状态,最终达到了对期望输出的渐近跟踪,同时系统状态有界。应用于电液位置伺服系统的仿真结果表明该控制策略是有效的,对系统不确定性和未知干扰具有较强的鲁棒性。     

非线性系统模糊神经网络直接自适应控制

提出一种基于模糊神经网络的自适应控制方法。由模糊神经网络构成非线性预测器，利用使预测输出等于参考输出，生成实时控制信号。对自适应算法进行了理论分析，结合实例进行了仿真。     

一类非线性非严格反馈系统的间接自适应神经网络控制

针对一类非严格反馈非线性系统,本文提出了间接自适应神经网络控制器的设计方案,并基于系统函数界函数的单调递增性质,提出了变量分离方法,同时利用间接自适应神经网络控制技术和Backstepping(反推)相结合的方法,构造出间接自适应神经网络状态反馈控制器,所构造的间接自适应控制器,保证了闭环系统的所有信号是半全局有界的,并且系统的所有状态收敛到原点充分小的邻域内,有效地解决了一类非线性非严格反馈系统的自适应神经网络控制问题,并采用数值例子进行仿真实验。仿真结果表明,在本文所提出的控制律的作用下,不但保证了闭环系统的稳定,而且保证所有信号在闭环系统有界。该控制器为一类非严格反馈非线性系统的稳定性控制提供了理论参考。     

一种局部递归神经网络模型及其在动态系统辨识中的应用

提出了一种局部递归神经网络模型,利用误差回馈原理推导了其学习算法,针对动态系统辨识问题,建立了一个基于该网络的并联辨识方案,仿真结果表明,该网络及其辨识结构具有学习效率高,逼近速度快和不需要要辨识对象的先验知识等特点。     

基于模糊神经网络的非线性系统预测函数控制研究

针对预测函数控制难以很好地实现非线性系统控制的问题,将模糊神经网络与预测函数控制相结合,设计一种基于模糊神经网络的非线性系统的预测函数控制器。用模糊神经网络辨识非线性系统的模型,辨识结果送到预测函数控制中,从而得到预测模型,最终得到最优的控制量。通过Matlab计算机仿真,可以看出此控制器对于非线性系统具有良好的控制效果和鲁棒性。     

一类含有滞回故障非线性系统Backstepping变结构控制

为解决执行器发生未知故障情况下不确定非线性系统的控制问题,采用一种自适应Backstepping变结构控制方法,建立了包括滞回非线性和失效、卡死等故障类型的非线性执行器模型.通过径向基函数(radial basis function,RBF)神经网络逼近系统中的未知非线性函数项,神经网络参数根据自适应律实时调整,保证了逼近效果.结合动态面控制,避免了Backstepping控制中的计算复杂性问题.引入的自适应补偿项消除了系统建模误差和不确定干扰的影响,理论分析证明了闭环系统半全局一致最终有界,仿真结果验证了该方法的有效性.     

一类非线性系统的神经网络鲁棒自适应控制

针对一类单输入单输出仿射非线性系统，提出了一类神经网络鲁棒自适应控制。设计过程中，采用RBF神经网络实现对系统中的未知非线性函数逼近，并考虑到存在逼近误差和外部干扰，采用滑模控制实现了系统的鲁棒控制。最后通过MATLAB仿真，证明了该方法的有效性。