Multi-channel FURLS algorithm for active noise control and simulation

为了改善最小均方(LMS)类算法在空间宽带噪声主动控制问题中收敛速度慢的缺点,消除声反馈对系统稳定性的影响.将快速收敛的最小二乘(RLS)类算法与自适应滤波U形结构结合,提出多通道滤波-URLS(MFURLS)算法,理论上推导该算法详细流程.本文对定频和宽带噪声进行了降噪仿真,将MFURLS算法与多通道滤波-ULMS(MFULMS)算法进行对比,仿真结果表明采用MFURLS算法的系统有30dB左右的降噪量,且收敛速度优于FULMS算法,证明该算法在宽带噪声控制方面具有很大优势.     

压缩机噪声的主动噪声控制系统研究

主动噪声控制系统是运用声学干涉相消的理论,由自适应算法对参考噪声进行处理来产生抗噪声信号。本文针对燃气站压缩机在中低频段具有声压级高且难以抵消的问题,首先对压缩机噪声进行时频分析,然后提出了一种基于自适应IIR的主动噪声控制系统,该系统由两个参数可调的数字滤波器和相对应的自适应算法组成。最后利用Xilinx FPGA作为系统的核心控制模块进行系统的硬件设计。实测结果表明该方法在中低频段降噪效果可达20dBA,系统收敛速度为30us,且消耗更少的硬件资源。     

基于RLS算法的自适应噪声抵消系统研究

介绍了一种基于RLS算法的自适应噪声对消系统,说明了噪声对消系统的原理以及RLS算法的步骤与流程。通过实例仿真,得到了基于RLS算法的自适应噪声抵消系统仿真图。分析仿真结果得出,在单频干扰与宽带噪声干扰两种情况下,RLS自适应滤波器都能很好地消除干扰得到有用信号。证实了在通信语音信号处理中,用基于RLS算法的自适应噪声对消系统可以消除语音噪声,提高语音通信的信号质量。     

简谐噪声在三维空间的主动控制及仿真

三维空间的噪声主动控制技术是近年来噪声控制领域研究的一个热点问题,对于降低飞机或车辆里的噪声水平有很大意义。提出了一种对于简谐噪声在三维空间进行精确控制的方法,先对三维空间建立几何模型,并且对几何模型进行网格划分,误差准则取所有节点处的声压平方和,然后在误差准则取得最小值的情况下,计算出次级声源的强度。最后对基于该方法设计的噪声主动控制系统进行仿真,仿真结果表明系统有15～30dB的最大降噪量,从而验证了该方法的有效性。     

前馈结构噪声有源控制算法的LabVIEW设计及仿真

有源噪声控制是近年来噪声控制领域研究的一个热点问题,适用于低频成分的噪声消除。本文以次为切入点,首先介绍了前馈结构有源噪声控制系统的组成,对其中所采用的自适应算法进行了详细讨论。然后针对有源噪声控制中的两种常用算法FXLMS和FXNLMS,在LabVIEW环境下设计了仿真程序,并进行仿真。通过仿真,比较了两种算法的鲁棒性、收敛速度等性能指标,得出了FXNLMS算法较FXLMS算法更适合实际应用的结论,为今后进一步的研究奠定了基础。     

非晶合金配电变压器噪声主动控制技术

本文中针对非晶合金配电变压器的噪声主动控制技术进行了研究,讨论了噪声主动控制的原理,分析了非晶合金变压器的噪声特性,介绍了应用于非晶合金变压器的噪声主动控制算法。     

基于自适应RBF神经网络的变压器噪声有源控制算法

针对现有变压器噪声有源控制算法存在的不足,提出了一种用于抑制噪声的新算法。该算法融合了自适应算法、粒子群算法、改进梯度下降算法及RBF神经网络算法。首先利用自适应算法确定降噪系统控制器中RBF神经网络隐含层节点个数和相应的参数;然后,根据切换策略自适应地选择粒子群算法或者改进梯度下降算法,用来优化节点数目和参数;最后,将优化得到的隐含层结构和参数反馈至系统控制器中,使系统的次级声源更好地抵消源声源。通过将所提的改进RBF神经网络法与未改进的RBF神经网络法和BP神经网络法进行比较,表明该算法可有效地提高降噪系统的自适应能力和抗干扰能力,且能够将噪声控制在较低的范围内,获得较理想的降噪效果。     

自适应噪声抵消系统的设计与性能仿真

LabVIEW作为一种图形化虚拟仪器编程语言,其在信号的生成、分析和处理上优势明显。利用其可以设计虚拟的自适应噪声抵消系统,从而可以应用于实际工程中对噪声抵消性能的测试验证。本文针对强噪声背景下有用信号的提取问题,介绍了自适应噪声抵消的原理,并对3种基本自适应滤波算法的步骤与流程进行了阐述。基于LabVIEW图形化虚拟仪器编程语言设计了虚拟自适应噪声抵消系统,系统结构简单,人机交互界面较好。在该系统下以3种自适应滤波算法为例仿真验证了的噪声抵消的性能,结果表明,3种自适应滤波算法的滤波性能与实际分析相符,验证了所设计系统的有效性和正确性。     

基于LMS算法自适应噪声抵消系统的仿真研究

介绍了自适应噪声抵消系统的原理和LMS算法,并给出了基于LMS算法自适应噪声抵消系统的仿真图。通过分析仿真结果表明基于LMS算法的自适应噪声抵消技术可以有效的抵消正弦干扰信号,这样在语音信号处理中就能消除含噪语音信号中的背景噪音,达到提高语音信号质量的目的。     

用于主动噪声控制系统的高性能算法结构

本文针对传统的自适应滤波算法降噪性能差、收敛速度慢以及应对突变能力不足等问题,提出了基于改进的方程误差算法和镜像优化算法。其中,改进的方程误差算法在FURLMS算法基础上进行离线二次路径建模,解决了降噪性能和收敛速度的问题。为了提高系统应对突变的能力,该算法在FURLMS算法基础上进行了镜像优化。结果表明,本文提出的两种算法在系统频率为250 Hz左右范围时,均方误差可稳定在-20dB,提出的改进方程误差算法和镜像修改算法分别有28dBA和30dBA的噪声衰减效果。     

A rapidly converging filtered‐error algorithm for multichannel active noise control

In this paper, a multichannel adaptive control algorithm is described which has good convergence properties while having relatively small computational complexity. This complexity is similar to that of the filtered‐error algorithm. In order to obtain these properties, the algorithm is based on a preprocessing step for the actuator signals using a stable and causal inverse of the minimum‐phase part of the transfer path between actuators and error sensors, the secondary path. The latter algorithm is known from the literature as postconditioned filtered‐error algorithm, which improves convergence rate for the case that the minimum‐phase part of the secondary path increases the eigenvalue spread. However, the convergence rate of this algorithm suffers from delays in the adaptation path because adaptation rates have to be reduced for larger delays. The contribution of this paper is to modify the postconditioned filtered‐error scheme in such a way that the adaptation rate can be set to a higher value. Consequently, the scheme also provides good convergence if the system contains significant delays. Furthermore, a regularized extension of the scheme is given which can be used to limit the actuator signals. Copyright © 2006 John Wiley & Sons, Ltd.     

基于遗传算法的有源消声系统设计

建立了基于遗传算法的自适应有源消声模型,介绍有源消声系统原理,自适应控制系统的关键在于其控制算法,用算法来调整滤波器的系数.在消声系统里必须考虑的因素主要有误差、声音的延迟、声音的衰减、在公式中适当的加入相位变化等.该系统结合神经网络算法,遗传算法和BP算法结合并改进提高了精度和准确性,可以用来优化神经网络的结构及其权值.实验分别从单音和复音情况进行,实验结果证明了基于神经网络算法的自适应有源消声系统有良好的消声效果,该系统稳定性较强.     

A new indirect adaptive algorithm for feedforward control with application to active noise cancellation

This paper considers the deterministic adaptive feedforward control problem for disturbance rejection. A new indirect adaptive control algorithm is presented as an alternative to the well-known ‘filtered-X LMS’ algorithm when the disturbance is periodic with unknown frequency and the plant, possibly non-minumum phase, is unknown. This new algorithm requires the solution of a Diophantine equation and a simple scheme to recursively solve this type of equation is suggested. the new algorithm is shown to converge without the use of a dither signal for plant modelling. Simulations demonstrate that the proposed algorithm has a substantially better transient response and convergence speed than the filtered-X LMS algorithm. the applicability of the algorithm to the adaptive active-noise-cancelling problem is demonstrated using an identified acoustic model.     

一种基于在线建模的自适应有源噪声控制快速算法

针对次级通路时变条件下的快速算法展开研究.首先分析了已有的基于次级通路在线建模的FxLMS算法,同时给出了带策略选择的权系数局布迭代算法;在此基础上,提出了一种针对次级通路在线建模的带策略选择的局布迭代有源控制快速算法.给出了该快速算法的实现步骤;比较了不同算法的运算量;就次级通路为时变与非时变两种情况下对算法进行了计算机仿真.结果表明,本文提出的快速算法能有效地降低原算法的运算量,提高原算法次级通路在线建模部分的性能,并可在稳态时取得较原算法更优的降噪量.     

A study on an active noise control system using an adaptive exponential filter

Active noise control systems that have been studied previously require a replica of the cancellation path to obtain the updating weight values, because the signals for the operation cannot be observed. In this paper we propose a structure and an adaptive algorithm for the active noise control system using an adaptive exponential filter that does not require any replica. The adaptive algorithm is based on the steepest descent method that can be easily realized and the updating weight value of the adaptive exponential filter is the correlation of the observable output signal of the adaptive system and the estimation error. The other adaptive filters are composed of the linear transversal system. It is proven that the transfer function after converging completely corresponds to the transfer function of the noise and the cancellation path under a certain condition. Finally, the convergence performance of the estimation accuracy and the tracking performance with respect to rapid changes of the noise and the cancellation paths are verified by computer simulation. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(1): 53–59, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10256     

Indirect current control of active filter for harmonic elimination with novel observer-based noise reduction scheme

Active power filters have been developed recently to solve the harmonics disturbance problems on power system networks. The direct current control scheme is generally used to control the harmonic compensating current directly for current source active power filters. To improve the characteristics of harmonic elimination, the voltage regulation scheme is proposed which regulates the filter capacitor voltage at the input side. Hence the voltage regulation scheme is an indirect current control technique for making sinusoidal line current. To implement this proposed scheme, the electronic differentiator should be used. By using the conventional differentiator, high frequency noise is generated in the controller. This deteriorates both the accuracy and reliability of the controller. To reduce this noise, a novel observer-based noise reduction scheme is proposed for our active filter system. The observer-based algorithm and characteristics of indirect current-controlled active filters are investigated through simulations and experiments.