Retrospective Cost Adaptive Control for Feedback and Feedforward Noise Control

This dissertation concerns the development of retrospective cost adaptive control (RCAC) and the application of RCAC to the active noise control (ANC) problem. We further the development of RCAC by presenting an alternative interpretation the retrospective performance variable. The retrospective performance decomposition is derived which separates the retrospective performance into the sum of a pseudo-performance term and a model-matching error term. We demonstrate an experimental application of RCAC by applying it to the broadband feedback road noise suppression problem in a vehicle. We show that RCAC is able to suppress the primary modes of the road noise at the performance microphone location. However, qualitative evaluation of the noise at the location of the driver was poor. This leads to the question, if you suppress the noise at the performance microphone, what is effect at the actual ear of the driver where you may not be able to place a sensor. The concept of spatial spillover is explored, where we develop an operator that relates relative suppression at the performance microphone to relative suppression at the evaluation microphone, which we denote as the spatial spillover function. The properties of the spatial spillover function are then validated numerically and experimentally. Finally, the framework of RCAC is extended to the feedforward control problem. Comparisons of RCAC feedforward control are made to linear-quadratic-Gaussian (LQG) control. It is shown that under certain conditions, RCAC is able to match the performance of LQG. Furthermore, we compare RCAC to the filtered-x/filtered-u least-mean-square (Fx/FuLMS) and the filtered-x/filtered-u recursive-least-square (Fx/FuRLS) algorithms and demonstrate numerically that RCAC is able to achieve better asymptotic performance that FuRLS. The RCAC feedforward control algorithm is demonstrated in an acoustic experiment. We demonstrate experimentally that if the ideal feedforward controller is implementable, the RCAC controller is able to recover the frequency response of the ideal controller.PHDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/140812/1/antai_1.pd

Comparison of smart panels for tonal and broadband vibration and sound transmission active control

This paper presents a comprehensive overview of the principal features of smart panels equipped with feed-forward and feedback systems for the control of the flexural response and sound transmission due respectively to tonal and to stochastic broadband disturbances. The smart panels are equipped with two types of actuators: first, distributed piezoelectric actuators formed either by small piezoelectric patches or large piezoelectric films bonded on the panels and second, point actuators formed by proof-mass electromagnetic transducers. Also, the panels encompass three types of sensors: first, small capacitive microphone sensors placed in front of the panels; second, distributed piezoelectric sensors formed by large piezoelectric films bonded on the panels and third point sensors formed by miniaturized accelerometers. The proposed systems implement both single-channel and multi-channel feed-forward and feedback control architectures. The study shows that, the vibration and sound radiation control performance of both feed-forward and feedback systems critically depends on the sensor-actuator configurations

Comparison of smart panels for tonal and broadband vibration and sound transmission active control

3noThis paper presents a comprehensive overview of the principal features of smart panels equipped with feed-forward and feedback systems for the control of the flexural response and sound transmission due respectively to tonal and to stochastic broadband disturbances. The smart panels are equipped with two types of actuators: first, distributed piezoelectric actuators formed either by small piezoelectric patches or large piezoelectric films bonded on the panels and second, point actuators formed by proof-mass electromagnetic transducers. Also, the panels encompass three types of sensors: first, small capacitive microphone sensors placed in front of the panels; second, distributed piezoelectric sensors formed by large piezoelectric films bonded on the panels and third point sensors formed by miniaturized accelerometers. The proposed systems implement both single-channel and multi-channel feed-forward and feedback control architectures. The study shows that, the vibration and sound radiation control performance of both feed-forward and feedback systems critically depends on the sensor-actuator configurations.reservedmixedGardonio P.; Turco E.; Dal Bo L.Gardonio, P.; Turco, E.; Dal Bo, L

An investigation of active structural acoustic control in resonant enclosures

This dissertation explores two topics in applied structural acoustics. First is the development of a methodology for passive redesign of the plate structure that decreases acoustic-structure coupling and the sound level in acoustic enclosures. The second topic explores the development and implementation of MIMO controllers that were robust and produced meaningful reductions of SPL in the destination enclosure. The scope of this work involved the modeling, simulation, construction, and implementation of these passive and active control concepts. Their performance was evaluated in both simulation and experiment tests. First a passive design methodology based on a parametrically defined FEM (finite element method) model, coupled to a BEM (boundary element method) acoustic model by the modal interaction model approach was developed. Then using FEMLAB (a finite element toolbox for Matlab), a model of the plate was developed and exported as m-code for sensitivity studies and design optimization. Numerous control approaches were then simulated on the state space model of the 3-D enclosure system. These simulations explored different algorithms, controller structures, and system arrangements to determine what approaches were best suited to the ASAC problem. Based on these simulations the required setups and control electronics hardware were designed and built. Then the experimental setup was identified for control design using a variety of standard frequency domain approaches. Finally these control design models were utilized to design and implement controller in experiment. The results and intuitions gained in this investigation are then discussed

SMART FOAM FOR ACTIVE VIBRATION AND NOISE CONTROL

A new class of smart foams is introduced to simultaneously control the vibration and noise radiation from flexible plates coupled with acoustic cavities. The proposed smart foam consists of a passive foam layer bonded to one surface of an active piezoelectric composite whose other surface is bonded to the surface of the vibrating plate. In this manner, the active piezoelectric composite can control from one side the porosity and the acoustic absorption characteristics of the foam and from the other side can suppress the vibration of the flexible plate. With such capabilities, the proposed smart foam can simultaneously control structural and acoustic cavity modes over a broad frequency range. A comprehensive theoretical study of the smart foam elements is introduced, in order to optimize the design and performance of this hybrid actuator. Feedback control of the reflected sound field was numerically and experimentally investigated, using an impedance tube, and showed a great improvement in the sound absorption coefficient. A finite element model is developed to study the interactions among the foam, the active piezoelectric composite, the flexible plate and an acoustic cavity. The developed finite element model is a reduced 2-dimensional model based on the 1st order shear deformation theory, which was compared with the original 3-dimensional model and it managed to capture all the dynamic characteristics of the foam provided a proper thickness to width ratio is maintained. The model enables the prediction of the plate vibration and the sound pressure level inside the acoustic cavity for a simple PD feedback control strategy of the active piezoelectric composite. It enables also the computation of the acoustic absorption characteristics of the foam. The predictions of the model are also validated experimentally. The developed theoretical and experimental techniques will provide invaluable tools for the design and application of the proposed smart foam to a wide variety of systems such as passenger cars, helicopter, aircraft cabins and other flexible enclosures, where their operation as quiet platforms is critical to the success of their mission

Active vibration control of doubly-curved panels

This thesis considers active control of the vibration of doubly-curved panels. Such panels are widely used in vehicles such as cars and aircraft, whose vibration is becoming more problematic as the weight of these vehicles is reduced to control their CO2 emissions. The dynamic properties of doubly-curved panels are first considered and an analytic model which includes in-plane inertia is introduced. The results of this analytical model are compared with those from numerical modelling. Of particular note is the clustering of lower-order modes as the curvature becomes more significant. The influence of these changes in dynamics is then studied by simulating the performance of a velocity feedback controller using an inertial actuator. The feasibility of implementing such an active control system on a car roof panel is then assessed.Experiments and simulations are also conducted on a panel, mounted on one side of a rigid enclosure, which is curved by pressurising the enclosure. The active control of vibration on this panel is then implemented using compensated velocity feedback control and novel inertial actuators. It is found that the performance of the feedback control initially improves as the curvature increases, since the fundamental natural frequency of the panel becomes larger compared with the actuator resonance frequency, but then the performance is significantly degraded for higher levels of curvature, since the natural frequencies of many of the panel modes cluster together. Finally, the integration of a compensator filter in the control system ensures the robustness of the system, despite changes in curvature, which makes it a good candidate for future multi-channel implementations

Aeronautical engineering: A continuing bibliography with indexes (supplement 275)

This bibliography lists 379 reports, articles, and other documents introduced into the NASA scientific and technical information system in Jan. 1991