156 research outputs found
Rapidly converging multichannel controllers for broadband noise and vibrations
Applications are given of a preconditioned adaptive algorithm for broadband multichannel active noise control. Based on state-space descriptions of the relevant transfer functions, the algorithm uses the inverse of the minimum-phase part of the secondary path in order to improve the speed of convergence. A further improvement of the convergence rate is obtained by using double control filters for elimination of adaptation loop delay. Regularization was found to be essential for robust operation. The particular regularization technique preserves the structure to eliminate the adaptation loop delay. Depending on the application at hand, a number of extensions are used for this algorithm, such as for applications with rapidly changing disturbance spectra, applications with large parametric uncertainty, applications with control of time-varying acoustic energy density
Adaptive multichannel control of time-varying broadband noise and vibrations
This paper presents results obtained from a number of applications in which a recent adaptive algorithm for broadband multichannel active noise control is used. The core of the algorithm uses the inverse of the minimum-phase part of the secondary path for improvement of the speed of convergence. A further improvement of the speed of convergence is obtained by using double control filters for elimination of adaptation loop delay. Regularization was found to be necessary for robust operation. The regularization technique which is used preserves the structure to eliminate the adaptation loop delay. Depending on the application at hand, a number of extensions are used for this algorithm. For an application with rapidly changing disturbance spectra, the core algorithm was extended with an iterative affine projection scheme, leading to improved convergence rates as compared to the standard nomalized lms update rules. In another application, in which the influence of the parametric uncertainties was critical, the core algorithm was extended with low authority control loops operating at high sample rates. In addition, results of other applications are given, such as control of acoustic energy density and control of time-varying periodic and non-periodic vibrations
Beam-steering digital num array paramétrico
Engenharia Electrónica e TelecomunicaçõesActualmente existem diversos m etodos que permitem a realiza c~ao de beamsteering
num altifalante param etrico. No entanto, a maioria dos m etodos e
incapaz de proporcionar uma elevada resolu c~ao angular usando um projecto
de hardware e ciente. Mais ainda, poucos s~ao os sistemas que proporcionam
um controlo do beam de pot^encia em tempo real.
Neste documento, e proposta uma nova abordagem para colmatar estes
problemas tirando partido da alta frequ^encia inerente a modula c~ao sigmadelta.
Esta implementa c~ao leva a um projecto compacto que proporciona
uma elevada resolu cao angular associada a uma solu c~ao de baixo custo e
com baixo consumo de pot^encia devido ao uso de apenas uma DAC sigmadelta.
O sistema implementado sobre FPGA alia a natural alta frequ^encia
dum modulador sigma-delta ao uso dum unico shift-register para introduzir
os atrasos necess arios a realiza c~ao de beam-steering. A escolha do atraso
adequado e feita com o uso de multiplexers que encaminham os diversos
sinais sigma-delta para as sa das do sistema desejadas.Several methods enable a steerable beam using an parametric loudspeaker.
However, many of them are not able to use a high angular resolution with
an e cient design. More, even the ability to change the beam steering
in real time is neglected by several methods. In this document, we propose
a new approach to the beam-steering problem using the intrinsic high
frequency of a sigma-delta digital to analog converter conjugated with online
con gurable digital delays obtained only through a programmable wide
shift-register. This implementation leads to a real time beam-steering with
a simple digital processing block that enables a high resolution angle. Additionally
the use of a sigma-delta DAC provides a low-cost, highly integrated
and energy e cient system using only a DAC.
The implemented system takes advantage of the high frequency of the digital
signal from the sigma-delta modulator allied with the use of a shiftregister
to obtain the ne time delays necessary to do the beam-steering.
The several outputs delays are chosen between the sigma-delta signals in
the shift-register using a group of multiplexers
Beam-steerng digital num array paramétrico
Mestrado em Engenharia Electrónica e TelecomunicaçõesActualmente existem diversos m etodos que permitem a realiza c~ao de beamsteering
num altifalante param etrico. No entanto, a maioria dos m etodos e
incapaz de proporcionar uma elevada resolu c~ao angular usando um projecto
de hardware e ciente. Mais ainda, poucos s~ao os sistemas que proporcionam
um controlo do beam de pot^encia em tempo real.
Neste documento, e proposta uma nova abordagem para colmatar estes
problemas tirando partido da alta frequ^encia inerente a modula c~ao sigmadelta.
Esta implementa c~ao leva a um projecto compacto que proporciona
uma elevada resolu cao angular associada a uma solu c~ao de baixo custo e
com baixo consumo de pot^encia devido ao uso de apenas uma DAC sigmadelta.
O sistema implementado sobre FPGA alia a natural alta frequ^encia
dum modulador sigma-delta ao uso dum unico shift-register para introduzir
os atrasos necess arios a realiza c~ao de beam-steering. A escolha do atraso
adequado e feita com o uso de multiplexers que encaminham os diversos
sinais sigma-delta para as sa das do sistema desejadas.Several methods enable a steerable beam using an parametric loudspeaker.
However, many of them are not able to use a high angular resolution with
an e cient design. More, even the ability to change the beam steering
in real time is neglected by several methods. In this document, we propose
a new approach to the beam-steering problem using the intrinsic high
frequency of a sigma-delta digital to analog converter conjugated with online
con gurable digital delays obtained only through a programmable wide
shift-register. This implementation leads to a real time beam-steering with
a simple digital processing block that enables a high resolution angle. Additionally
the use of a sigma-delta DAC provides a low-cost, highly integrated
and energy e cient system using only a DAC.
The implemented system takes advantage of the high frequency of the digital
signal from the sigma-delta modulator allied with the use of a shiftregister
to obtain the ne time delays necessary to do the beam-steering.
The several outputs delays are chosen between the sigma-delta signals in
the shift-register using a group of multiplexers
Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control
Recent implementations of multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations provide considerably improved performance over traditional adaptive algorithms. The most significant performance improvements are in terms of speed of convergence, the \ud
amount of reduction, and stability of the algorithm. Nevertheless, if the error in the model of the relevant transfer functions becomes too large then the system may become unstable or lose performance. On-line adaptation of the model is possible in principle but, for rapid changes in the model, necessitates \ud
a large amount of additional noise to be injected in the system. It has been known for decades that a combination of high-authority control (HAC) and low-authority control (LAC) could lead to improvements with respect to parametric uncertainties and unmodeled dynamics. In this paper a full digital implementation of such a control system is presented in which the HAC (adaptive MIMO control) is implemented on a CPU and in which the LAC (decentralized control) is implemented on a high-speed Field Programmable Gate Array. Experimental results are given in which it is demonstrated that the HAC/LAC combination leads to performance advantages in terms of stabilization under parametric uncertainties and reduction of the error signal
ACTIVE NOISE CONTROL USING CARBON NANOTUBE THERMOPHONES: CASE STUDY FOR AN AUTOMOTIVE HVAC APPLICATION
The goal of this project was to reduce the overall noise levels emitted by the HVAC components in a vehicle’s cabin. More specifically, the feasibility of achieving this goal using two key technologies was investigated.
The first of these technologies, Active Noise Control (ANC), is a noise attenuation technique that relies on destructive interference that “cancels” unwanted noise. Typically used in situations where physical constraints prevent passive attenuation techniques from being used, ANC is known for its high size-to-effectiveness ratio. This benefit cannot be gained without a cost however; the complexity of ANC systems is significantly higher than their passive counterparts. This is due to the signal processing and actuator designs required. These actuators often take the form of moving-coil loudspeakers which, while effective, are often bulky. Because of this they are difficult to “drop in” to an existing system.
This is where the second technology comes in. Carbon Nanotube (CNT) Thermophones are solid-state speakers that operate by using rapid heat fluctuations to create sound. Called the “thermoacoustic effect,” (TE) the theory of this operating principle dates to the turn of the 20th century. Useful demonstration of TE did not occur until 2008, however, when researchers first developed the first CNT thermophones. The hallmark characteristics of these transducers are their small size and flexible nature. Compared to traditional loudspeakers they have a much smaller form factor and are more versatile in terms of where they can be placed in a cramped system.
The marriage of CNT transducers to ANC technology shows promise in improving the application space and ease of installation of ANC systems. Getting these two to cooperate, however, is not without challenges.
A case study for this union is presented here; the application space being the ducted environment of vehicle HVAC systems
In Car Audio
This chapter presents implementations of advanced in Car Audio Applications. The system is composed by three main different applications regarding the In Car listening and communication experience. Starting from a high level description of the algorithms, several implementations on different levels of hardware abstraction are presented, along with empirical results on both the design process undergone and the performance results achieved
Power electronic interfaces for piezoelectric energy harvesters
Motion-driven energy harvesters can replace batteries in low power wireless sensors, however selection of the optimal type of transducer for a given situation is difficult as the performance of the complete system must be taken into account in the optimisation. In this thesis, a complete piezoelectric energy harvester system model including a piezoelectric transducer, a power conditioning circuit, and a battery, is presented allowing for the first time a complete optimisation of such a system to be performed. Combined with previous work on modelling an electrostatic energy harvesting system, a comparison of the two transduction methods was performed. The results at 100 Hz indicate that for small MEMS devices at low accelerations, electrostatic harvesting systems outperform piezoelectric but the opposite is true as the size and acceleration increases. Thus the transducer type which achieves the best power density in an energy harvesting system for a given size, acceleration and operating frequency can be chosen.
For resonant vibrational energy harvesting, piezoelectric transducers have received a lot of attention due to their MEMS manufacturing compatibility with research focused on the transduction method but less attention has been paid to the output power electronics. Detailed design considerations for a piezoelectric harvester interface circuit, known as single-supply pre-biasing (SSPB), are developed which experimentally demonstrate the circuit outperforming the next best known interface's theoretical limit. A new mode of operation for the SSPB circuit is developed which improves the power generation performance when the piezoelectric material properties have degraded. A solution for tracking the maximum power point as the excitation changes is also presented.Open Acces
Coluna de som utilizando array de transdutores de ultrasons
Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e TelecomunicaçõesEste relatório documenta a Tese de Mestrado com o tema Audio Spotlight - Coluna de Som utilizando Arrays de Transdutores de Ultrassons realizado por Paulo Jaime Estrela Janganga.
Este trabalho assenta na implementação de um sistema de áudio direcional Audio Spotlight.
Atualmente começam-se a dar os primeiros passos ao nível da comercialização de produtos com este tipo de tecnologia. No entanto, existem ainda aspetos técnicos que necessitam de ser resolvidos antes da sua aplicação no nosso dia -a-dia.
O problema principal é a distorção que um sistema deste tipo gera ao utilizar interações não lineares de ondas de alta frequência (ultrassons) para gerar ondas de baixa frequência dentro da gama audível pelos seres humanos. Depois de resolvido este e outros problemas adjacentes ao sistema, o seu potencial é promissor, sendo a lista de aplicações práticas e comerciais muito abrangente. Alguns exemplos são:
• Num automóvel, em que cada um dos ocupantes poderá ouvir a sua própria música, sem perturbar os companheiros de viagem;
• Numa conferência, onde cada membro da audiência poderá ouvir o áudio no seu idioma, sem recorrer à utilização de headphones;
• Em sistemas de anúncios sonoros nas ruas e praças, que poderão ser substituídos por mensagens áudio direcionadas a cada um dos transeuntes, eliminando a polui ção sonora.
Esta tese está organizada em três partes:
1. Teoria e Evolução de sistemas de Audio Spotligh;
2. Implementação do Sistema de Audio Spotlight na FPGA Spartan 3E;
3. Implementação do Sistema de Audio Spotlight no DSP TMS320C6713;
4. Resultados experimentais.
A primeira parte introduz todos os aspetos teóricos referentes à tecnologia, para que seja possível compreender os fenómenos físicos e a matemática associ ada a um sistema deste tipo.
Na segunda parte é explicada a forma como o sistema foi implementado na FPGA Spartan 3E, com a explicação de todos os módulos constituintes da aplicação. A terceira parte é idêntica à segunda, mas desta vez a implementação é realizada no DSP TMS320C6713. Na última parte é feita a demonstração experimental dos conceitos aplicados nesta tese recorrendo à captura de sinal com osciloscópio.Abstract: This report documentary Master's Thesis with the theme Audio Spotlight - Sound Column using Ultrasound Transducers Arrays conducted by Paul Jaime Estrela Janganga.
This work will be based on the implementation of an Audio Spotlight system, which is a way audio technology. These days, begin to take the first steps in terms of marketi ng of such products, but there are still some issues that need to be resolved before the technology really come on a day-to-day of all of us. The main problem is the distortion that generates such a system by using nonlinear interaction of high frequency w aves (ultrasound) to generate low frequency waves audible to humans.
After solved the problems surrounding the system, the benefits are huge with a list of practical applications and virtually endless commercials:
• In a car each occupant can listen to you r own music, without disturbing fellow travelers;
• At a conference, each audience can receive the sound in your language, without the use of headphones in the ears;
• Ad systems on the streets and squares may be replaced by targeted messages to each of th e passers-by, eliminating noise pollution.
This document is divided into three distinct parts:
1. Theory and Evolution of Audio Spotlight systems.
2. Implementation of the Audio Spotlight system in Spartan 3E FPGA.
3. Implementation of the Audio Spotlight system in the TMS320C6713 DSP.
The first part will introduce all the theoretical aspects related to technology, so you can understand the physical phenomena and the mathematics associated with such a system.
In the second part it is explained how the system was implemented in FPGA Spartan 3E, with the explanation of all the constituent modules of the application.
The third part is identical to the second, but this time the implementation is done in DSP TMS320C6713.
At the end of the last two parts there is an area reserved for testing in order to view the results, especially through oscilloscope captures
Efficient audio signal processing for embedded systems
We investigated two design strategies that would allow us to efficiently process audio signals on embedded systems such as mobile phones and portable electronics. In the first strategy, we exploit properties of the human auditory system to process audio signals. We designed a sound enhancement algorithm to make piezoelectric loudspeakers sound "richer" and "fuller," using a combination of bass extension and dynamic range compression. We also developed an audio energy reduction algorithm for loudspeaker power management by suppressing signal energy below the masking threshold. In the second strategy, we use low-power analog circuits to process the signal before digitizing it. We designed an analog front-end for sound detection and implemented it on a field programmable analog array (FPAA). The sound classifier front-end can be used in a wide range of applications because programmable floating-gate transistors are employed to store classifier weights. Moreover, we incorporated a feature selection algorithm to simplify the analog front-end. A machine learning algorithm AdaBoost is used to select the most relevant features for a particular sound detection application. We also designed the circuits to implement the AdaBoost-based analog classifier.PhDCommittee Chair: Anderson, David; Committee Member: Hasler, Jennifer; Committee Member: Hunt, William; Committee Member: Lanterman, Aaron; Committee Member: Minch, Bradle
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