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针对无人机编队飞行时存在的气动耦合和外部干扰等影响因素,提出基于“长-僚机”模式的神经网络自适应逆控制器设计方法.详细推导了气动耦合影响,建立了完整的编队飞行非线性数学模型,设计了非线性动态逆控制律,提出了改进的 BP 神经网络算法,自适应地逼近和在线补偿动态逆误差,改善了控制效果,并针对队形变换提出了简单有效的设计思想.仿真表明,该控制器能有效实现编队队形的保持或变换,控制系统结构具有良好的扩充性. 相似文献
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光电位置敏感传感器(PSD),特别是其B区存在非线性误差大、测量精度低的问题.针对现有神经网络校正方法的不足,提出一种基于思维进化计算(MEC)算法优化的神经网络校正模型.该方法首先应用MEC算法搜索最优神经网络初始权值和阈值,再利用LM算法训练BP神经网络,最后将训练好的神经网络用于PSD非线性校正.仿真实验结果表明,所提出的方法校正精度高,收敛速度快,泛化能力强,测试数据的平均误差被控制在0.005 mm以下.经过校正后的PSD在非线性区表现出与线性区相似的线性程度,提高了PSD的测量精度. 相似文献
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基于混合神经网络的非线性预测函数控制 总被引:5,自引:1,他引:5
针对基本预测函数控制只能用于线性对象的控制这一不足,提出了基于混合神经网络的非线性预测函数控制.混合神经网络由BP网络和线性神经网络串连组成.采用混合神经网络对可用Hammerstein模型描述的非线性对象进行有效的辨识.其中,BP网络反映了非线性静态增益,线性神经网络反映了线性动态子系统.利用BP网络求出非线性静态增益的逆并与非线性对象串联,抵消非线性对象中的非线性静态增益部分,将非线性对象的控制问题转化为对线性对象的控制问题,实现了对非线性对象的预测函数控制.当被控对象的特性发生变化时,可对混合神经网络权值及时进行修正并调整控制器参数使控制系统始终保持良好的控制性能.仿真结果表明,此控制系统具有良好的控制效果. 相似文献
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针对开关磁阻电动机的非线性特点及其现有建模方法存在初始网络权值参数随机给定和易于陷入局部最小点的缺点,提出了一种采用并行优化混沌BP神经网络的建模方法。该方法首先利用混沌系统对神经网络权值向量、阈值向量进行初始优化,然后利用BP神经网络的Levenberg-Marquardt算法进行收敛训练,如果陷入局部最小点则再次使用并行混沌搜索进一步优化模型,使模型具有精度高、速度快的特点。模型训练和开关磁阻电动机调速系统动态仿真结果表明,采用该方法建立的模型运行平稳,系统动态性能好,响应速度快。 相似文献
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提出一种基于动态粒子群算法的神经网络训练方法。神经网络权值选择是否合适直接关系到其非线性拟合能力,通过引入动态粒子群算法对神经网络进行训练,对神经网络各层连接权值进行优化。经过函数测试表明,相比粒子群算法,动态柱子群算法收敛速度更快且不易陷入局部,能更快更合理地训练神经网络从而优化网络连接权值。 相似文献
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研究造纸工业中的流浆箱非线性系统优化控制问题。流浆箱系统是工业过程中常见的一类非线性系统,存在着非线性、强耦合等特性。针对流浆箱要求动态响应好、精度高的特点,提出并设计了人工鱼群算法训练的PID神网络控制器。人工鱼群算法克服了PID神经网络采用BP算法训练权值时,初始权值难以确定,易陷入局部最优的缺点,实现对流浆箱的有效控制。在MATLAB环境下,对流浆箱系统进行了控制仿真。仿真结果表明,人工鱼群算法训练的PID神经网络在动态性、稳定性和精确性等方面均优于BP算法,明显改善了流浆箱这类非线性系统的控制性能,具有很好的应用效果。 相似文献
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基于PID神经网络的非线性动态系统控制 总被引:2,自引:0,他引:2
基于PID神经网络的控制器可以完成变量的单输入-单输出非线性系统的任务.该控制器采用BP(误差反向传播)算法来修正连接权重值,通过在线训练和学习,使目标函数到达最优值.充分利用了BP神经网络算法逼近任意连续有界非线性函数的能力,显示了神经网络在解决非线性系统方面的潜能.为了达到控制的目的,和其他非线性建模技术相比较,PID神经网络有几个明确的优点和它独特的用法相一致.仿真结果表明,在对非线性动态系统控制时,基于PID神经网络的控制系统具有很强的灵活和高效性,能取得良好的控制效果. 相似文献
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基于Hammerstein 模型的感应电机变频器调速系统神经网络控制 总被引:1,自引:0,他引:1
针对感应电机变频器调速系统的非线性特点,提出一种基于Hammerstein模型的神经网络控制方法。 Hammerstein模型由静态非线性模块和动态线性模块组成。首先,利用ARMA模型实现对感应电机变频器调速系统的线性动态模块辨识;然后,基于该辨识模型,实现调速系统非线性静态模块神经网络逆模型辨识与系统直接逆控制;最后,针对控制过程中存在的电机负载扰动问题,设计了神经网络直接逆控制器在线学习与控制策略。仿真实验表明,所提出的控制策略可以获得满意的控制效果。 相似文献
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The servo-motor possesses a strongly nonlinear property due to the effect of the stimulating input voltage, load-torque and environmental operating conditions. So it is rather difficult to derive a traditional mathematical model which is capable of expressing both its dynamics and steady-state characteristics. A neural network-based adaptive control strategy is proposed in this paper. In this method, two neural networks have been adopted for system identification (NNI) and control (NNC), respectively. Then, the commonly-used specialized learning has been modified, by taking the NNI output as the approximation output of the servo-motor during the weights training to get sensitivity information. Moreover, the rule for choosing the learning rate is given on the basis of the analysis of Lyapunov stability. Finally, an example of applying the proposed control strategy on a servo-motor is presented to show its effectiveness. 相似文献
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The servo-motor possesses a strongly nonlinear property due to the effect of the stimulating input voltageload-torque and environmental operating conditions.So it is rather diffcult to derive a traditional mathematical model which is capable of expressing both its dynamics and steady-state characteristics.A neural network-based adaptive control strategy is proposed in this paper.In this method,two neural networks have been adopted for system identification(NNI)and control(NNC),respectively.Then,the commonly-used specialized learning has been modified,by taking the NNI output as the approximation output of the servo-motor during the weights training to get sensitivity information.Moreover,the rule for choosing the learning rate is given on the basis of the analysis of Lyapunov stability.Finally,an example of applying the proposed control strategy on a servo-motor is presented to show its effectiveness. 相似文献
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基于NARX网络的无刷直流电机自适应逆控制 总被引:1,自引:0,他引:1
针对无刷直流电机(bnmhless DC motor,BLDCM)非线性的特点,引入了一种基于神经网络的自适应逆控制方法.该方案中,用非线性自回归(NARX)动态网络做为模型辨识器和控制器.辨识器采用了BP(back propagation)算法在线调整参数,并获取被控时象精确的Jacobian信息,再由实时递归学习算法(RTRL)实现对控制器的在线整定.仿真结果表明,方法具有响应速度较快、无超调的优点,且具备较强的自适应性和鲁棒性. 相似文献
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Neural network controller with flexible structure based on feedback-error-learning approach 总被引:2,自引:0,他引:2
In practice, the back-propagation algorithm often runs very slowly, and the question naturally arises as to whether there are necessarily intrinsic computation and difficulties with training neural networks, or better training algorithms might exist. Two important issues will be investigated in this framework. One establishes a flexible structure, to construct very simple neural network for multi-input/output systems. The other issue is how to obtain the learning algorthm to achieve good performance in the training phase. In this paper, the feedforward neural network with flexible bipolar sigmoid functions (FBSFs) are investigated to learn the inverse model of the system. The FBSF has changeable shape by changing the values of its parameter according to the desired trajectory or the teaching signal. The proposed neural network is trained to learn the inverse dynamic model by using back-propagation learning algorithms. In these learning algorithms, not only the connection weights but also the sigmoid function parameters (SFPs) are adjustable. The feedback-error-learning is used as a learning method for the feedforward controller. In this case, the output of a feedback controller is fed to the neural network model. The suggested method is applied to a two-link robotic manipulator control system which is configured as a direct controller for the system to demonstrate the capability of our scheme. Also, the advantages of the proposed structure over other traditional neural network structures are discussed. 相似文献
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Karim H. Youssef Hasan A. Yousef Omar A. Sebakhy Manal A. Wahba 《Expert systems with applications》2009,36(2):3454-3458
This paper introduces the use of the adaptive particle swarm optimization (APSO) for adapting the weights of fuzzy neural networks (FNN) on line. The fuzzy neural network is used for identification of the dynamics of a DC motor with nonlinear load torque. Then the motor speed is controlled using an inverse controller to follow a required speed trajectory. The parameters of the DC motor are assumed unknown as well as the nonlinear load torque characteristics. In the first stage a nonlinear fuzzy neural network (FNN) is used to approximate the motor control voltage as a function of the motor speed samples. In the second stage, the above mentioned approximator is used to calculate the control signal (the motor voltage) as a function of the speed samples and the required reference trajectory. Unlike the conventional back-propagation technique, the adaptation of the weights of the FNN approximator is done on-line using adaptive particle swarm optimization (APSO). The APSO is based on the least squares error minimization with random initial condition and without any off-line pre-training. Simulation results are presented to prove the effectiveness of the proposed control technique in achieving the tracking performance. 相似文献
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A direct modified Elman neural networks (MENNs)-based decentralized controller is proposed to control the magnets of a nonlinear and unstable multi-input multi-output (MIMO) levitation system for the tracking of reference trajectories. First, the operating principles of a magnetic levitation system with two moving magnets are introduced. Then, due to the exact dynamic model of the MIMO magnetic levitation system is not clear, two MENNs are combined to be a direct MENN-based decentralized controller to deal with the highly nonlinear and unstable MIMO magnetic levitation system. Moreover, the connective weights of the MENNs are trained online by back-propagation (BP) methodology and the convergence analysis of the tracking error using discrete-type Lyapunov function is provided. Based on the direct and decentralized concepts, the computational burden is reduced and the controller design is simplified. Furthermore, the experimental results show that the proposed control scheme can control the magnets to track various periodic reference trajectories simultaneously in different operating conditions effectively. 相似文献
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In this paper, performance oriented control laws are synthesized for a class of single‐input‐single‐output (SISO) n‐th order nonlinear systems in a normal form by integrating the neural networks (NNs) techniques and the adaptive robust control (ARC) design philosophy. All unknown but repeat‐able nonlinear functions in the system are approximated by the outputs of NNs to achieve a better model compensation for an improved performance. While all NN weights are tuned on‐line, discontinuous projections with fictitious bounds are used in the tuning law to achieve a controlled learning. Robust control terms are then constructed to attenuate model uncertainties for a guaranteed output tracking transient performance and a guaranteed final tracking accuracy. Furthermore, if the unknown nonlinear functions are in the functional ranges of the NNs and the ideal NN weights fall within the fictitious bounds, asymptotic output tracking is achieved to retain the perfect learning capability of NNs. The precision motion control of a linear motor drive system is used as a case study to illustrate the proposed NNARC strategy. 相似文献