Download or read book Simultaneous Online Modeling of the Secondary Path and Neutralization of the Feedback Path in an Active Noise Control System written by Shauk Muntaha Murshid Khan and published by . This book was released on 2014 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation Into the Practical Implementation of Online Secondary Path Modelling in Single Channel Feedforward Active Noise Control Systems written by Lawrence Hau Rhun Wong and published by . This book was released on 2015 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Active Noise Control (ANC) systems, the online modelling of the Secondary Path is an important topic of research. This functionality, achieved by the injection of modelling noise, is vital to the successful stable operation for noise attenuation, particularly when the Secondary Path is time varying due to its acoustic nature. A notable weakness is that there is a lack of experimental data available. The research discussed in this thesis presents experimental data obtained by replicating existing online modelling methods in NI compactRIO-9082 hardware. This thesis investigates the online modelling performance and noise attenuation of Akhtar's MFxLMS (Modi ed - FxLMS) method. The experimental results produced demonstrated two things. Firstly the MFxLMS fails to operate on a higher control step size parameter compared to the FxLMS al-gorithm, most likely due to complications arisen from implementing in a physical environment. Secondly, the restriction of the modelling noise amplitude is a requirement for stable and accurate Secondary Path modelling. Two other existing algorithms are also implemented. Each algorithm has its own criterion for injecting and suspending modelling noise. Extensive testing of these two methods shows that one system is better at suspending modelling noise once filter convergence is achieved. This prevents the Secondary Path estimate from destabilising even though modelling accuracy is reduced. It is suggested that while modelling accuracy and modelling stability are different from each other, modelling stability is a more important factor to consider as modelling accuracy is dependent on stability. Two methods of online secondary path modelling are proposed as improvements from the ANC systems already tested in this research investigation. It is shown that the appropriate ne tuning of the FwFxLMS (Filtered-w FxLMS) algorithm improves noise attenuation convergence at the expense of operational stability. The second proposed method incorporates a third modelling filter, an idea initially proposed by Zhang. The experimental results show that the using an additional modelling filter improves the quality of the error signal used for the online modelling of the Secondary Path. This in turn improves the modelling accuracy of the Secondary Path and the overall stability of the ANC system.
Download or read book Active Noise Control Systems written by Jianming Tsai and published by . This book was released on 1993 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Active Control of Noise and Vibration written by Colin Hansen and published by CRC Press. This book was released on 1996-11-21 with total page 1292 pages. Available in PDF, EPUB and Kindle. Book excerpt: This major work is the first to treat the active control of both sound and vibration in a unified way. It outlines the fundamental concepts, explains how a reliable and stable system can be designed and implemented, and details the pitfalls . It covers sound in ducts, sound radiation, sound transmission into enclosures, structural vibration and isolation, electronic control system design, and sensors and actuators.
Download or read book Active Control of Impact Acoustic Noise written by Guohua Sun and published by . This book was released on 2013 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active noise control (ANC) has drawn widespread research interest in both academia and industry during the last two decades, especially in the automotive industry where better vehicle noise, vibration and harshness (NVH) performance is one of the important concerns for vehicle manufacturers. However, most of the current state-of-the-art ANC systems are mainly focused on stationary noises by following Gaussian distribution, and there is limited research work on ANC of impulsive and/or impact noise. In practice, there are many unwanted impact responses at industrial sites and in motor vehicles, such as noise generated by punching machines, combustion engines and pile drivers as well as impact road noise due to road bumps. This type of noise may pose a difficult challenge for the prevalent adaptive control algorithms, namely the filtered-x least mean square (FXLMS) algorithm. Hence, more in-depth understanding is required to design an ANC system with robust and efficient adaptive algorithms for treating impact acoustic noise. The first part of the dissertation concentrates on the development of more robust adaptive algorithms for generic impulsive noise. First, an enhanced modified filtered-x least mean M-estimate algorithm (MFXLMM) is proposed to tackle the impulsive-type noise, where the reference signal is fed through the Hampel's three-part M-estimator by setting thresholds for impulses. Second, a family of enhanced M-estimator based algorithms is proposed, where different types of robust criteria based on robust statistic theory are applied for non-Gaussian impulsive noise. This family of algorithms generalizes all the existing studies by previous researchers. Third, more specific observations are made for the convergence performance of the modified FXLMS algorithm for impact noise, where thresholds in the reference and error signal paths are added. This analysis is to address the underlying mechanism of the enhanced algorithm for impact noise due to the white noise and impulses with different durations. The second part of the dissertation is on impact noise with certain repetitiveness. First, a specific analytical convergence analysis of the FXLMS algorithm for repetitive impulse-induced noise is developed, where pure delay secondary path models are assumed. A step size bound is obtained which is in agreement with the previous studies. Moreover, a general secondary model is considered in the numerical simulations to further demonstrate the feasibility of applying the FXLMS algorithm for repetitive impact noise. Second, comparative experimental and simulation work are conducted to further validate the performance of FXLMS algorithm for repetitive impact noise. The feedback system with the iterative learning control (ILC) algorithm is also designed to compare with the FXLMS algorithm. Finally, a concluding work is performed to apply the enhanced FXLMS algorithm to impact road noise control. A frequency response function (FRF)-based sub-structuring technique is implemented to develop a coupled vehicle system model, where the passenger compartment is simplified as a 3-dimensional flexible-panel backed cavity model and the tire-wheel system is modeled as a flexible ring element and rigid wheel. Numerical simulations are conducted to validate the effectiveness of the proposed ANC system for interior impact road noise.
Download or read book Stability Analysis of Adaptation Process in FxLMS based Active Noise Control written by Iman Tabatabaei Ardekani and published by . This book was released on 2011 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is concerned with the Filtered-x Least Mean Square (FxLMS) adaptation algorithm and its applications in Active Noise Control (ANC). Generally, this algorithm is used in system identification problems in which a physical channel, called the secondary path, follows the adaptive filter. The FxLMS algorithm compensates for the secondary path effect by filtering the input signal (training data sequence) using an available estimate of the secondary path, called the secondary path model. However, this filtering causes the analytical model of the adaptation process to become highly complex. Because of this complexity, this model has to be simplified when it is desired to derive closed-form expressions for formulating different behaviours of the adaptation process. Usually, this simplification has been carried out by using unrealistic assumptions of pure delay secondary paths, broad-band acoustic noise, and perfect secondary path models. The first contribution of this thesis is the derivation of a set of closed-from mathematical expressions for formulating behaviours of FxLMS-based ANC systems in steady-state and transient conditions. This derivation is carried out without using any simplifying assumption regarding the secondary path. Consequently, the obtained expressions extend the available knowledge on FxLMS-based ANC systems. The second contribution is formulating influences of acoustic noise band-width on the newly-derived expressions. In the analysis of ANC systems with stochastic noise, it is usual to assume a broad-band acoustic noise with a flat frequency spectrum (which is usually referred to as a white signal), in order to avoid mathematical complexity. However, even if the acoustic noise has a flat spectrum over a wide frequency range, the signal picked up and fed to the ANC system is required to be processed with a sampling frequency higher than the maximum frequency of the acoustic noise. For this reason, a realistic noise signal can only have a flat spectrum over a limited band-width. The third contribution is investigating influences of secondary path models on the newly-derived expressions. Usually, it is acceptable to assume a perfectly-accurate secondary path model; however, in order to generalise the obtained closed-form expressions, this assumption is also removed in this thesis. Consequently, the final closed-form expressions, proposed in this thesis, can apply to a relatively general case with an arbitrary secondary path, an acoustic noise with an arbitrary band-width, and an arbitrary (imperfect) secondary path model. Another contribution of this thesis is determining trajectories of the poles of the FxLMS adaptation process in the z-plane. This investigation leads to find the FxLMS adaptation process root locus. It is shown that the dominant pole of this locus always locates on a certain branch with a typical trajectory in the z-plane. A mechanism for localising this pole is then proposed in this thesis, resulting in a novel ANC algorithm, called the Filtered Weight FxLMS. In addition to several numerical analyses and computer simulations, a FPGA-based ANC setup, developed for this research, is used to study the validity of the theoretical results obtained in this thesis. This setup is developed by using a flexible FPGA programming structure which can be used for the implementation of other ANC algorithms. Different experiments with this setup confirms the validity of the theoretical results proposed in this thesis.
Download or read book Real Time Nonlinear Filtered X LMS Algorithm for Active Noise Control written by Mouayad Sahib and published by LAP Lambert Academic Publishing. This book was released on 2015-04-02 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: In practical active noise control (ANC) applications, nonlinearity effects degrade the performance of conventional linear control algorithm. The nonlinearity sources could originate from the noise process, primary and secondary acoustical propagation paths, or from the transducers consisting of loudspeaker, microphone or amplifier. In this book, a new method of modelling the saturation effect of the amplifier based on tangential hyperbolic function (THF) of the nonlinear part of a Hammerstein model structure is proposed. The THF modelling scheme can be incorporated into an established real time nonlinear FXLMS termed THF-NLFXLMS algorithm. The developed THF-NLFXLMS algorithm is tested by means of simulation and implemented experimentally using FPGA-based real time controller for a nonlinear ANC application. The application involves the reduction of a traffic noise that affects the pressure field in a bedroom. The ANC architecture implemented is a single channel internal model control (IMC) based feedback ANC system.
Download or read book A Method for Detecting Convergence Completion of Adaptive Filter Cancelling Feedback Path Appeared in Active Noise Control Systems written by Kensaku Fujii and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Evaluation of Current Adaptive Active Duct Noise Control Algorithms written by Michael David Lucey and published by . This book was released on 1996 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Active Noise Cancellation written by Vasant S. Shridhar and published by . This book was released on 2010 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On line Modeling and Feedback Compensation Techniques for 3 D Active Noise Control Systems written by Jian Luan and published by . This book was released on 1993 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimal Feedback Control Formulation of the Active Noise Cancellation Problem written by K. C. Zangi and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unwanted noise is a by-product of many industrial processes and systems. In active noise cancellation (ANC), one introduces a secondary noise source to generate an acoustic field that interferes destructively with the unwanted noise, and thereby attenuates it. Noise reduction is important to protect listeners in high noise environments from hearing damage, to enhance speech communication, and to reduce noise-induced fatigue. These adverse effects of noise can cause accidents and reduce the productivity of workers. By formulating the ANC problem as an optimal feedback control problem, we developed a single approach for designing stochastically optimal feedback controllers for pointwise and distributed active noise cancellation. In the pointwise case, we develop an optimal feedback controller for attenuating the acoustic pressure at the locations of a finite number of microphones. In the distributed case, we develop an optimal feedback controller for attenuating the total acoustic energy in an enclosure. In either case, the controller is pointwise and is obtained as the output of an ordinary pressure microphone.
Download or read book Feedback Active Noise Control Systems written by Dipa Vijayan and published by . This book was released on 1994 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Parallel Path Difference Algorithm for Active Noise Cancellation written by Yong Yan and published by . This book was released on 1992 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimal Feedback Control Formulation of the Active Noise Cancellation Problem written by Kambiz Casey Zangi and published by . This book was released on 1994 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Noise Cancellation in the Presence of Feedback and Output error path Dynamics written by Kirk Robert Everman and published by . This book was released on 1992 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Active Noise Control Internet Resources written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
