EP0636287A1 - Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable - Google Patents

Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable

Info

Publication number
EP0636287A1
EP0636287A1 EP92916034A EP92916034A EP0636287A1 EP 0636287 A1 EP0636287 A1 EP 0636287A1 EP 92916034 A EP92916034 A EP 92916034A EP 92916034 A EP92916034 A EP 92916034A EP 0636287 A1 EP0636287 A1 EP 0636287A1
Authority
EP
European Patent Office
Prior art keywords
control system
vibration
resonator means
resonator
noise
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP92916034A
Other languages
German (de)
English (en)
Other versions
EP0636287A4 (fr
EP0636287B1 (fr
Inventor
Andrew Langley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Noise Cancellation Technologies Inc
Original Assignee
Noise Cancellation Technologies Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Noise Cancellation Technologies Inc filed Critical Noise Cancellation Technologies Inc
Priority to AT92916034T priority Critical patent/ATE186614T1/de
Priority claimed from PCT/US1992/003024 external-priority patent/WO1993021687A1/fr
Publication of EP0636287A1 publication Critical patent/EP0636287A1/fr
Publication of EP0636287A4 publication Critical patent/EP0636287A4/fr
Application granted granted Critical
Publication of EP0636287B1 publication Critical patent/EP0636287B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/129—Vibration, e.g. instead of, or in addition to, acoustic noise
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3028—Filtering, e.g. Kalman filters or special analogue or digital filters
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3045—Multiple acoustic inputs, single acoustic output
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3227—Resonators
    • G10K2210/32271—Active resonators
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/50—Miscellaneous
    • G10K2210/501—Acceleration, e.g. for accelerometers

Definitions

  • the vibration typically comprises a fundamental component whose frequency is, for example, the rotation frequency of the machine (this is called the first harmonic), plus one or more additional harmonics at frequencies that are integer multiples of the first.
  • a tuned damper is a resonant system that is attached to a point where vibration is to be reduced, and it is built to resonate at or close to the frequency of the vibration. Purely passive tuned dampers have fixed characteristics, and will work only close to the frequency for which they are designed.
  • the input impedance of the resonator (defined as the ratio of a generalized force applied by the resonator at the point of attachment to a generalized velocity at the same point) will be exceptionally high (or in some cases, such as a Helmholtz resonator in a duct, exceptionally low: see the description in L E Kinsler, A R Frey, A B Coppens, J V Sanders “Fundamentals of Acoustics” 3rd ed. Wiley and Sons 1982 pp 241-242).
  • a mass suspended on a spring will resonate at a characteristic resonance frequency. If the spring is attached to a structure vibrating at this resonance frequency, the amplitude of vibration of the structure at that point will be reduced (and as a consequence, the suspended mass will vibrate strongly). Similar effects can be described for acoustic resonators (eg. Helmholtz resonators; L E Kinsler, A R Frey, A B Coppens, J V Sanders “Fundamentals of Acoustics” 3rd ed. Wiley and Sons 1982. pp 225-228) where sound pressure is the vibration to be reduced.
  • acoustic resonators eg. Helmholtz resonators; L E Kinsler, A R Frey, A B Coppens, J V Sanders “Fundamentals of Acoustics” 3rd ed. Wiley and Sons 1982. pp 225-228) where sound pressure is the vibration to be reduced.
  • An ideal adaptive-passive system would be able to control components of vibration at several different frequencies (usually the first and subsequent harmonics of a quasi-periodic vibration), whilst maintaining the performance of the system as the frequencies change.
  • the damper is a Helmholtz resonator, and the control systems use the sound pressure level inside the resonator, and just outside it, as inputs. Both control systems aim to adjust the resonators such that the phase shift between the two inputs is 90 , when the resonator will be at resonance.
  • Sato and Matsuhisa use a two-stage control system that estimates the frequency of the sound from the inputs and uses an open-loop control system initially to tune the damper close to that frequency. A second stage of closed-loop control then iterates to tune the damper precisely to the correct frequency, although there is no description of the control algorithm.
  • This system must derive the vibration frequency initially from one of the inputs, which can be difficult if the fundamental period of vibration is changing and the vibration comprises several harmonics all of which will be changing differently. Also, the control system does not allow several tuned dampers to be tuned to reduce several different frequencies in the sound simultaneously.
  • the invention provides for a noise or vibration control system comprising the following features
  • control system that has as inputs the sensors, and as outputs, signals to change the resonance frequencies of the resonators wherein the control system incorporates an algorithm to tune the resonators close to selected frequencies in the noise or vibration, and to keep them tuned as those frequencies drift (or as other factors affecting resonator performance change).
  • a still further object is to have a vibration control system with sensors attached to the source or the structure (or any other suitable location) that can be used to determine the frequencies of the noise or vibration
  • a still further object is the provision of vibration control with optional additional sensors that are used to monitor other factors that affect the resonators' performances (such as temperature)
  • control system that has as inputs the sensors, and as outputs, signals to change the resonance frequencies of the resonators wherein the control system incorporates an algorithm to tune the resonators close to selected frequencies in the noise or vibration, and to keep them tuned as those frequencies drift.
  • control system incorporates mathematical models of the resonators that are used to enhance the performance of the control system.
  • these models are continuously updated and refined by the control system as it operates.
  • FIG. 2 A very simple example of the invention will be vised to illustrate the important features.
  • a structure 1 is excited by a source 2 vibrating at a variable fundamental frequency of f .
  • the spectrum of the vibration contains harmonics at f , 2f , 3f .... etc.
  • a source 2 vibrating at a variable fundamental frequency of f .
  • the spectrum of the vibration contains harmonics at f , 2f , 3f .... etc.
  • a spring-mass-damper resonator 3 is attached. It Is assumed in this example that the nth harmonic of the fundamental component of the vibration is to be reduced by the damper, so that the aim is to tune the resonator close to nf , and to keep it tuned as f drifts.
  • structure bears the vibration from the source to the resonator, and may be a solid, fluid or gas depending on the application.
  • vibration includes any disturbance in the “structure”, including electromagnetic, as the techniques described here can be equally well applied to mechanical or electrical systems.
  • An accelerometer 4 is attached to the mass of the resonator, and another accelerometer 5 is attached to the structure close to the resonator.
  • the displacement of the mass (as monitored via the accelerometer 4) is denoted x , and the displacement of the structure m
  • m s frequency response of the sensor can usefully include any other additional filtering (eg analogue bandpass filtering and gain adjustment to improve signal to noise ratios or anti-aliasing). This compensation for the sensor responses can be applied at different points in the system, but it is most efficient to apply the compensation to the coefficients X and X described below. m s
  • control system will store necessary information about the calibration of the sensors to enable any corrections that are required to be made. In the description below, these corrections are not explicitly stated as it will be obvious to anyone skilled in the art how to compensate for sensor characteristics to derive the quantities needed by the control system.
  • the aim is to maximize the modulus of the input impedance of the resonator at the nth harmonic of the fundamental of vibration, so that the structure will vibrate less at that frequency at the point of attachment of the resonator.
  • the input impedance is defined here to be the ratio of the force applied by the structure to the resonator and the corresponding velocity of the point of attachment, and it is a function of frequency.
  • Re(X e ) are the components in x and x at angular frequency ⁇ . s m s
  • ⁇ is the undamped resonance (angular) frequency of the resonator
  • Q is the "quality factor”.
  • a frequency sensor 6 in figure 2 is provided to detect the fundamental frequency of vibration, f .
  • the location and type of sensor is preferably chosen to be reasonably immune to the effects of changing the tuning of the resonator.
  • It could be a tachometer signal from a part of the source of vibration such that the output of the tachometer can be used to determine the current fundamental frequency of the source.>•
  • it may be sufficient to use one or more of the sensors mounted on the structure and resonators to derive fundamental frequencies, but it is better if the sensor is insensitive to the effects of tuning the resonators.
  • the signal from sensor 6 is used by the control system 7 to help to discriminate those components of x and x at the frequency nf in m s 1 the presence of components at other harmonics of f or any other "noise". This discrimination is crucial if the control system is to be able to alter the resonance frequency of the resonator to coincide with nf and to maintain this condition as f varies. For example, x
  • the signal from sensor 6 can be used in several different ways to process the inputs from accelerometers 4 and 5. Three examples are given below.
  • a tracking bandpass filter whose centre frequency is adjusted by the signal from sensor 6 to be close to nf (eg. see K Martin and A S Sedra, IEEE Transactions on Acoutics, Speech and Signal Processing Vol A ⁇ SP-29 no. 3 June 1981 pp 736-744).
  • the bandwidth of the filter is chosen to reject all unwanted components in the accelerometer signals.
  • Each accelerometer signal is then filtered through a tracking filter (desirably, these filters would be identical) to leave only the signals at a frequency of nf .
  • One problem with this implementation is that the bandwidth of the filter (expressed in octaves) will have to vary with the number, n, of the harmonic to be controlled. This is because harmonics become more closely spaced (in terms of octaves) as n is increased.
  • the accuracy with which sensor 6 must detect f depends upon the required bandwidth of the filter. If »the filter bandwidth must be narrow to remove an unwanted noise component close to nf , then the accuracy with which the filter's centre frequency is set (by the signal from sensor 6) must clearly be such that the pass-band still includes the frequency nf . It is immaterial whether the tracking filter is implemented digitally or with analogue electronics.
  • the output of the bandpass filters will be signals that contain information only at the frequency nf , as required.
  • nf the frequency of the complex coefficients X and X
  • the low-pass filters described for the harmonic filter can have a bandwidth of up to 2f .
  • a single FFT or DFT is all that should be required to calculate X and m
  • auxiliary signals sin(2 ⁇ nf t) and cos(2 ⁇ nf t) For example, this could be done with 1 l voltage-controlled oscillators whose inputs would be a signal derived from sensor 6 to generate outputs close to frequency nf .
  • the signals x and x are then multiplied by sin(2 ⁇ nf t) and cos(2 ⁇ nf t) (giving
  • each of the" results is low-pass filtered by filters whose bandwidths are adjusted to reject all the unwanted components in x and x .
  • the bandwidths of the low-pass filters should be less than f .
  • the low-pass filters should have bandwidths that are ideally adjusted by the control system as f changes in order to maintain rejection of unwanted components in the signals (see G P Eatwell, "Control System Using Harmonic Filters”. Copending patent application).
  • the accuracy with which the frequency of the auxiliary signals must match nf depends upon the required bandwidth of the low-pass filters: the difference between the true value of nf and the frequency of the auxiliary signals derived from sensor 6 must be less than the bandwidth of the low-pass filters.
  • I X X r 2 (y 2 + m ⁇ DC y 2 OS )/(y 2 SC + y 2 S ⁇ ) and the phase difference by
  • Arg(X /X ) arctan(y /y ) - arctan(y /y ) m s ms c ss sc
  • Another method of using the auxiliary signal from sensor 6 to discriminate against unwanted components in x and x is to use a m s
  • the pulse-train can be used to select samples from ADC's triggered by a fixed clock running at a frequency considerably higher than Nf (using interpolation extrapolation if necessary to get the sample value at the occurrence of a pulse, which may lie between two successive samples of the ADC's).
  • the result of this process is a sequence of samples of x and x , with N samples per in s fundamental period of the vibration.
  • N is a suitable number.
  • the "Fast Fourier Transform” algorithm can be used; see D E Newland “An Introduction to Random Vibrations and Spectral Analysis” Longman 1975 pp 150-166). It is also possible to perform a Discrete Fourier Transform (see 6. D E Newland “An Introduction to Random Vibrations and Spectral Analysis” Longman 1975 pp 113-124).
  • the result of this process is one or more "Fourier Coefficients", representing the real and imaginary parts of X and X at one or more m s of the frequencies f , 2f ...nf ...Nf /2.
  • the coefficient at nf will have to be calculated when this is the harmonic of the vibration that is to be reduced).
  • Noise in x and x that is not correlated to the pulse-train can also m s be reduced by averaging corresponding Fourier coefficients from successive blocks of data (this is frequency-domain averaging, another example of a standard technique).
  • the control system must arrange to adjust the tuning of the resonator accordingly.
  • the modulus of the ratio Xm/Xs is to be maximized, or the phase difference between X and Xs is to be kept at
  • controller a gradient-descent algorithm incorporating a model of the resonator is used.
  • the purpose of the model is to permit rapid and accurate estimation of the derivatives of an error function that determines the current performance of the system.
  • the controller can be configured continuously to update its model of the resonator, and to account for additional variables (such as temperature) that affect the system performance.
  • Equation 1 is a result based on a simple model of the resonator. In practice, this model should be a good approximation at least reasonably close to resonance. If r is defined to be the ratio Xs/Xm evaluated at a frequency of nf , then equation 1 gives
  • the aim of the control system is to adjust ⁇ r to minimize Irl.
  • ⁇ will be a function of a control parameter ⁇ .
  • ⁇ may be the position of an actuator that changes the stiffness of the spring in the spring-mass-damper resonator. From the current value of ⁇ , denoted ⁇ , the improved value of ⁇ to be set by the controller
  • Equation 3 Is of limited use because the derivative of r with respect to ⁇ is not measured (whereas r is). It would be possible to determine the value of this derivative by making small perturbations in ⁇ and observing the results, but it is better to use the model of the resonator to estimate this derivative.
  • equation 2 gives the value of r in terms of the current values of ⁇ and Q. Therefore, an estimate of the r derivative is given by
  • Q can be r estimated in a similar fashion.
  • the derivatives with respect to ⁇ can also be estimated from the model relationships between ⁇ , Q and ⁇ . r
  • r can be derived from measurements of the sound pressure in the duct just outside the neck of the resonator, and inside the cavity of the resonator. As before, r itself should be measured rather than estimated in view of its sensitivity to errors when ⁇ ⁇ . However, r the derivative required in equation 3 can safely be estimated in the manner described above via the relation
  • ⁇ is a constant independent of ⁇ and the resonator performance, and the derivative is evaluated at the current value of ⁇ .
  • the best value for ⁇ can be selected by experiment. Initially, it may happen that the resonator is far from resonance. Two schemes can then be applied to bring the resonator close enough to resonance to apply the gradient-descent algorithm.
  • ⁇ is known from the sensor 6 signal, and an estimate of ⁇ Is known from r the current value of ⁇ and the relation between ⁇ and ⁇ r which is stored by the controller. Therefore, it is simple to adjust ⁇ in one step to bring ⁇ much closer to ⁇ .
  • the relation between ⁇ and ⁇ will In general not be known very accurately since, for example, the relation may depend upon unobserved variables such as temperature.
  • the second scheme a measurement-based one-step algorithm, estimates ⁇ directly by solving equation 2 for ⁇ - given the current (measured) r ⁇ values of ⁇ and r, and an estimate of Q. This determines the required change in ⁇ , and an update of X can be computed via r
  • X X + ⁇ ( ⁇ - ⁇ )/d ⁇ k+l k ⁇ r r ax
  • the derivative is evaluated at a value of ⁇ corresponding to a frequency somewhere between ⁇ and ⁇ , and ⁇ is a positive control parameter that would usually be somewhat less than 1.
  • ⁇ is a positive control parameter that would usually be somewhat less than 1.
  • a value of 1 tries to converge to the correct value of X in one step.
  • This method relies on the assumption that the gradient d ⁇ dX r is less sensitive to error than the resonance frequency itself.
  • This update equation can be applied iteratively, if necessary, to bring the resonator close enough to resonance for the gradient-descent algorithm to be applied.
  • ⁇ and Q may also be functions of parameters other r than ⁇ .
  • temperature may affect the resonance frequency.
  • the control system can still update these relationships as described above, the only difference being that these relationships now involve ⁇ and the additional variables instead of just ⁇ .
  • more than one harmonic of the vibration will usually be controlled. This is easily performed with the addition of one resonator per harmonic to be controlled, plus at least one additional sensor on each of the resonators. (The sensor 5 on the structure can be used to determine the vibration at all of the harmonics to be controlled, whereas a separate sensor is needed on each of the resonators). With the processing of the signals described above, the control of each resonator is largely independent.
  • the source generates more than one harmonic sequence of vibration.
  • the set of fundamental frequencies, f , f f should be resolved either from a single

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

Cette invention se rapporte à des systèmes de régulation destinés à la régulation du bruit et des vibrations. Des résonateurs (3) à fonctions réglables sont utilisés conjointement avec un système de régulation électronique (7) afin de modifier le bruit ou les vibrations dans une structure (1). L'invention se rapporte notamment à la régulation de bruit ou de vibrations quasi périodiques comportant au moins un harmonique à l'aide d'au moins un résonateur adaptable (3).
EP92916034A 1992-04-15 1992-04-15 Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable Expired - Lifetime EP0636287B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT92916034T ATE186614T1 (de) 1992-04-15 1992-04-15 Verbesserte vibriationsunterdrückungsschaltung mit adaptivem resonator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA002118210A CA2118210C (fr) 1992-04-15 1992-04-15 Systeme adaptatif de controle des vibrations a resonateurs
PCT/US1992/003024 WO1993021687A1 (fr) 1992-04-15 1992-04-15 Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable

Publications (3)

Publication Number Publication Date
EP0636287A1 true EP0636287A1 (fr) 1995-02-01
EP0636287A4 EP0636287A4 (fr) 1996-02-07
EP0636287B1 EP0636287B1 (fr) 1999-11-10

Family

ID=4153119

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92916034A Expired - Lifetime EP0636287B1 (fr) 1992-04-15 1992-04-15 Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable

Country Status (2)

Country Link
EP (1) EP0636287B1 (fr)
CA (1) CA2118210C (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2905973A1 (de) * 1979-02-16 1980-08-28 Gauting Gmbh Apparatebau Schwingungstilger
DE3025794A1 (de) * 1980-07-08 1982-01-21 Didier-Werke Ag, 6200 Wiesbaden Einrichtung zum bekaempfen von bei befeuerten industrieoefen, insbesondere winderhitzern auftretenden schwingungen
EP0195850A2 (fr) * 1985-03-26 1986-10-01 Barry Wright Corporation Système actif d'isolation des vibrations
EP0211173A2 (fr) * 1985-07-31 1987-02-25 Barry Wright Corporation Système d'isolation active contre les vibrations utilisant un fluide électro-rhéologique
EP0215999A1 (fr) * 1985-07-31 1987-04-01 Barry Wright Corporation Système actif à commande de paramètre pour l'isolation de vibrations
EP0300445A1 (fr) * 1987-07-20 1989-01-25 Nissan Motor Co., Ltd. Procédé de commande d'un amortisseur
US4981309A (en) * 1989-08-31 1991-01-01 Bose Corporation Electromechanical transducing along a path

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2905973A1 (de) * 1979-02-16 1980-08-28 Gauting Gmbh Apparatebau Schwingungstilger
DE3025794A1 (de) * 1980-07-08 1982-01-21 Didier-Werke Ag, 6200 Wiesbaden Einrichtung zum bekaempfen von bei befeuerten industrieoefen, insbesondere winderhitzern auftretenden schwingungen
EP0195850A2 (fr) * 1985-03-26 1986-10-01 Barry Wright Corporation Système actif d'isolation des vibrations
EP0211173A2 (fr) * 1985-07-31 1987-02-25 Barry Wright Corporation Système d'isolation active contre les vibrations utilisant un fluide électro-rhéologique
EP0215999A1 (fr) * 1985-07-31 1987-04-01 Barry Wright Corporation Système actif à commande de paramètre pour l'isolation de vibrations
EP0300445A1 (fr) * 1987-07-20 1989-01-25 Nissan Motor Co., Ltd. Procédé de commande d'un amortisseur
US4981309A (en) * 1989-08-31 1991-01-01 Bose Corporation Electromechanical transducing along a path

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9321687A1 *

Also Published As

Publication number Publication date
CA2118210C (fr) 1998-08-04
EP0636287A4 (fr) 1996-02-07
EP0636287B1 (fr) 1999-11-10
CA2118210A1 (fr) 1993-10-28

Similar Documents

Publication Publication Date Title
US5621656A (en) Adaptive resonator vibration control system
EP0568129B1 (fr) Système d'atténuation du bruit
US5386472A (en) Active noise control system
US4715559A (en) Apparatus and method for global noise reduction
US5321759A (en) Active noise control system for attenuating engine generated noise
EP0674305B1 (fr) Arrangement de contrôle du bruit ou vibration
EP0609846B1 (fr) Dispositif de contrôle des vibrations ou du bruit
CA1334284C (fr) Dispositif de traitement de signaux servant a detecter un signal periodique en presence d'un parasite periodique
US6772074B2 (en) Adaptation performance improvements for active control of sound or vibration
AU665565B2 (en) Noise reduction system
US5473698A (en) Method of controlling the application of counter-vibration to a structure
US4950966A (en) Adaptive vibration canceller
WO1990002380A1 (fr) Systeme d'annulation actif selectif pour phenomenes repetitifs
WO1992015088A1 (fr) Procede et appareil servant a affaiblir les vibrations acoustiques dans un milieu
US5469087A (en) Control system using harmonic filters
KR960011152B1 (ko) 능동 진동제어 시스템 및 이를 포함하는 내연기관 구동차량
WO1993021687A1 (fr) Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable
EP0636287B1 (fr) Systeme de regulation de vibrations ameliore au moyen d'un resonateur adaptable
EP0805432A2 (fr) Méthode avec rétroaction pour contrÔle du bruit avec entrées et sorties multiples
WO1991010226A1 (fr) Systeme actif de reduction des vibrations
JP3265715B2 (ja) 車両用能動型振動制御装置及び車両用能動型騒音制御装置
WO1994000911A9 (fr) Systeme de commande utilisant des filtres harmoniques
EP0904035A1 (fr) Systeme actif de commande de retroaction pour rejet des perturbations a bande etroite transitoire sur une large plage spectrale
JPH0830335A (ja) 周期的振動低減装置
JP3611180B2 (ja) 周期性信号の適応制御方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19941014

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE

A4 Supplementary search report drawn up and despatched
AK Designated contracting states

Kind code of ref document: A4

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE

17Q First examination report despatched

Effective date: 19980512

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19991110

Ref country code: LI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19991110

Ref country code: GR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19991110

Ref country code: ES

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19991110

Ref country code: CH

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19991110

Ref country code: BE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19991110

REF Corresponds to:

Ref document number: 186614

Country of ref document: AT

Date of ref document: 19991115

Kind code of ref document: T

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REF Corresponds to:

Ref document number: 69230294

Country of ref document: DE

Date of ref document: 19991216

ITF It: translation for a ep patent filed

Owner name: DE DOMINICIS & MAYER S.R.L.

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20000210

ET Fr: translation filed
NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000415

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MC

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20001031

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050415

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20070313

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 20070314

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20070410

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20070430

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20070529

Year of fee payment: 16

Ref country code: FR

Payment date: 20070404

Year of fee payment: 16

PGRI Patent reinstated in contracting state [announced from national office to epo]

Ref country code: IT

Effective date: 20080301

EUG Se: european patent has lapsed
GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20080415

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20081101

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20081231

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080415

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080415

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080415

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080416