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WO1997046176A1 - Systeme actif de commande de retroaction pour rejet des perturbations a bande etroite transitoire sur une large plage spectrale - Google Patents

Systeme actif de commande de retroaction pour rejet des perturbations a bande etroite transitoire sur une large plage spectrale Download PDF

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Publication number
WO1997046176A1
WO1997046176A1 PCT/US1997/009527 US9709527W WO9746176A1 WO 1997046176 A1 WO1997046176 A1 WO 1997046176A1 US 9709527 W US9709527 W US 9709527W WO 9746176 A1 WO9746176 A1 WO 9746176A1
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Prior art keywords
frequency
excitations
control system
feedback
control
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.)
Ceased
Application number
PCT/US1997/009527
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English (en)
Inventor
Rahmat A. Shoureshi
Daniel J. Maguire
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Cooper Tire and Rubber Co
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Cooper Tire and Rubber Co
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Application filed by Cooper Tire and Rubber Co filed Critical Cooper Tire and Rubber Co
Priority to EP97927930A priority Critical patent/EP0904035A4/fr
Publication of WO1997046176A1 publication Critical patent/WO1997046176A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
    • G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
    • 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
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
    • 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
    • G10K11/1787—General system configurations
    • G10K11/17875—General system configurations using an error signal without a reference signal, e.g. pure feedback
    • 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
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • 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
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G10K11/17883—General system configurations using both a reference signal and an error signal the reference signal being derived from a machine operating condition, e.g. engine RPM or vehicle speed
    • 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
    • G10K2210/121—Rotating machines, e.g. engines, turbines, motors; Periodic or quasi-periodic signals in general
    • 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
    • G10K2210/125—Transformers
    • 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
    • G10K2210/128—Vehicles
    • G10K2210/1281—Aircraft, e.g. spacecraft, airplane or helicopter
    • 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
    • G10K2210/128—Vehicles
    • G10K2210/1282—Automobiles
    • 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
    • G10K2210/3025—Determination of spectrum characteristics, e.g. FFT
    • 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
    • G10K2210/3026—Feedback
    • 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
    • G10K2210/3053—Speeding up computation or convergence, or decreasing the computational load
    • 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
    • G10K2210/511—Narrow band, e.g. implementations for single frequency cancellation

Definitions

  • This invention is related to systems for attenuating noise and vibration, including the nulling of primary excitations and the attenuation of narrow-band and frequency limited broad-band noise and vibrations using control signals that are applied through actuators.
  • tatement of the Problem Various systems have been proposed for actively reducing vibrations and noise. In general, these prior art systems can be divided into four groups. From a control view point, these can be either feedforward or feedback, and based on excitation source characteristics they are either for repetitive or random excitations. Almost all prior art systems utilize some form of computer or digital signal processing (DSP) board to implement their techniques.
  • DSP digital signal processing
  • US Patents Nos. 5,245,552 and 5,233,540 concentrate on digital estimation of a feed-forward active control for single or multiple repetitive vibrations. These systems use filters, phase differentiator, and digital signal processors that are used to identify an individual peak. Its frequency and phase lag are compared to a reference signal to develop a feed-forward control action for those identified frequencies.
  • US Patent No. 5,133,017 describes a seat with noise suppression near the occupant's ears using a direct feedforward signal and a controller that tries to estimate frequency and phase delay between the source and the detecting sensor at individual frequencies.
  • US Patent Nos. 5,337,366, 5,278,780, and 5,408,532 describe an active control apparatus using adaptive digital filters that try to estimate, on-line, primary and secondary paths using FIR filters.
  • Extensive digital signal processing for one-dimensional duct flow examples has been used to implement the proposed system.
  • the upper bound of frequency range is very sensitive to the computational power of the digital processor.
  • US Patent No. 4,654,871, 4,562,589, 5,170,433 have focused on harmonic synthesis type active noise control, using a direct feed-forward scheme that utilizes at least one reference signal containing those harmonics.
  • On-line microprocessors are used to estimate amplitude and phase required for the control signal.
  • US Patent NoS. 5,206,911, 5,396,561, 5,172,416, 4,677,677, and 4,677,676 demonstrate feedforward control using FIR filters to estimate primary and secondary paths dynamics, and a performance signal for adaptation of the filters' coefficients. Digital signal processors are used to implement and derive these filters on line. Controller performance is very limited by the complexity of the system and available processing power. Stability is also of concern.
  • US Patent No. 5,117,401 discloses another feed-forward active noise canceller using adaptive digital filters that have inserted delays for a more stable closed loop system. These delays are estimated off-line to reduce on-line computations. US Patent Nos.
  • 5,140,640 and 5,192,918 describe a feedforward adaptive noise control that utilizes a white noise pass through an adaptive filter, namely Widrow's linear combiner, to synthesize a colored noise which is equal in magnitude but out of phase with the original input noise or excitation.
  • Digital signal processors are used to implement the adaptive filter.
  • US Patent Nos. 5,337,365 and 5,245,664 describe an apparatus for actively reducing noise in the interior of an enclosed space using two sets of adaptive FIR digital filters and a microprocessor.
  • the objective of this feedforward controller is to use a reference signal and FIR filters for estimation of primary and secondary paths to synthesize the control signal.
  • US Patent No. 5,388,160 and 5,416,845 combine ideas of
  • US Patent Nos. 5,384,853 and 4,878,188 add a residual noise detector to the FIR adaptive filter approach to provide an active noise control system that incorporates background level detection.
  • US Patent No. 5,332,061 extends the concept of feedforward repetitive noise control, using an adaptive digital filter, to the problem of active vibration attenuation generated by engine excitation in a vehicle.
  • US Patent Nos. 5,146,505 and 5,222,148 use the adaptive filter and reference signal for harmonic noise control induced by an engine.
  • US Patent Nos. 5,293,578 and 5,319,715 introduce devices that operate on a pure feedforward control based on an adaptive wave synthesis concept. Band pass filters are used to identify individual frequencies. Adaptive delays and gain adjustments are added to the reference signal to calculate an appropriate output signal. These adaptations take place using a digital signal processor.
  • US Patent Nos. 5,416,844 and 5,111,507 use a reference signal with the same frequency as the excitation signal and an adaptive digital filter to estimate primary and secondary paths. In case of the vehicle noise control, signals from the crank angle and fuel injection valve are used. The overall scheme is a feedforward control approach.
  • US Patent No. 5,377,276 utilizes two sets of adaptive digital filters for its feedforward control. One set concentrates on the periodic component of the noise and the other set handles the random component. Adaptive filters are implemented by means of digital signal processing boards.
  • US Patent No. 5,091,953 utilizes a plurality of sensors to detect individual frequencies of a repetitive excitation source, then utilizes feedforward adaptive digital filters to synthesis the control signal.
  • Feedforward and feedback controllers differ in a few significant ways. Feedforward controllers require a feedforward sensor to provide future information to the controller about what is going to occur in the disturbance spectrum. This sensor typically needs to be information rich, an accurate estimate of the disturbance, and must sufficiently lead the disturbance to allow for the digital signal processing. In the case of the feedforward control algorithm of harmonic synthesis, the feedforward sensor is a tachometer and, so, is less costly.
  • a tachometer sensor only provides frequency information and not magnitude information, requiring costly digital signal processing components to adapt the magnitude of the control effort.
  • feedback control does not use a feedforward sensor, thus reducing cost.
  • a feedback controller must be designed to be robust, or reject disturbances across the entire spectral range of the disturbance. Stability criterion dictates that the performance at each point along the spectrum of the disturbance must be decreased with a widening spectral rejection range.
  • the present invention addresses the shortcomings and introduces a true feedback controller with concentrated feedback action and consequently, high performance, for a finite number of transient attenuation regions across a near-infinitely wide disturbance range.
  • This invention provides a system for single or multiple narrow-band vibration or noise disturbance rejection for bands transient across a wide spectral range by applying feedback control to the region via actuators and continuously tracking the dominant frequencies and adapting to the excitation frequencies.
  • the narrow-band excitation vibration or noise are sensed by one or more sensors.
  • a plurality of parallel bandpass filters are used for isolating peak frequencies.
  • the center frequencies of these bandpass filters are directly controlled, by analog or digital means, allowing the bands to move across the frequency spectrum in response to the sensed input noise or vibration excitations.
  • the isolated bands are separately delayed in a fixed or scheduled fashion to assure that disturbances within each narrow band will be 180 degrees out-of-phase when the signal (electrical, acoustic, or vibratory) completes the feedback path.
  • Sensors are located in the region to provide information about the residual noise or vibration in the form of feedback signals to the control unit.
  • the present invention provides discrete bands of feedback attenuation which can provide increased attenuation due to the relatively narrow width of the band. These bands then track the disturbances in frequency using a disturbance tracking system or sensor, resulting in significantly more attenuation at the location of the disturbance peaks over what can be achieved by the prior art including robust control and harmonic synthesis controllers and mechanisms.
  • a key feature of this control system is the ability to implement it using computer hardware or inexpensive analog and pseudo-analog components.
  • the control methodology results in a significant reduction in computational intensity, allowing the computer hardware to be lower cost.
  • the analog and pseudo-analog implementation provide identical performance with a significant reduction in cost.
  • This form of implementation also eliminates the constraints of throughput which are present with digital processing.
  • Signal conditioning of the feedback signal is very dependent upon the domain of the plant (acoustic, electrical, mechanical, structural) being controlled and dynamic characteristics of the plant (minimum phase or non- minimum phase) .
  • the difficulty is in the accounting of the relative delay and gain associated with each frequency component within the disturbance signal. Feedback controllers accounting for these broadband characteristics must generally be custom designed for each plant.
  • the present system is capable of tracking periodic disturbances and adjusting the feedback cancellation band to envelope the frequency of the disturbances to be attenuated. Due to the narrow-band characteristics, it is applicable to a much wider array of applications and does not require the exhaustive design of conventional feedforward or feedback control systems.
  • the tracking signal is provided to the feedback cancellation system from a direct sensor signal, e.g. tachometer, mounted on the machinery generating the undesired disturbance.
  • the varying tachometer signal causes the center frequencies of the feedback attenuation bands to overlay the correspondingly varying disturbance frequencies.
  • an indirect tachometer type signal is generated from a separate disturbance sensor capable of measuring a primary disturbance periodic frequency which can be used to determine and track the frequencies of this and other undesirable disturbance signals.
  • a third aspect of the invention uses a separate disturbance sensor and a spectrum analysis device to estimate the frequencies of the undesirable periodic components of the disturbance. This information is then used to program programmable feedback bandpass filters to center the disturbance attenuation bands about the primary disturbance frequencies.
  • the fourth aspect of the invention uses a fixed phase- delay mechanism, such as an analog, digital, or pseudo- analog allpass filter or tapped delay line to cause the 180 degree phase inversion. This aspect is applicable to cases where the phase roll-off of the feedback path is sufficiently slow and/or the disturbance peaks are sufficiently immobile to guarantee that the feedback phase error will not be significant enough to cause instability.
  • a fifth aspect of this invention uses the information provided from whichever tracking sensor or frequency estimation mechanism to control an adjustable phase-delay mechanism, such as an analog, digital, or pseudo-analog allpass filter or programmable tapped delay line to cause the 180 degree phase inversion.
  • the sixth aspect of the invention uses a fixed gain to provide sufficient feedback control effort to cause disturbance rejection without instability. This aspect is applicable to cases where the gain of the feedback loop is sufficiently flat throughout the range of the disturbance peaks.
  • a seventh aspect of this invention uses the information provided from whichever tracking sensor or frequency estimation mechanism to control an adjustable gain mechanism, such as an analog variable gain amplifier or mixed-signal multiplying digital-to-analog controller, to cause sufficient feedback control effort for disturbance rejection without instability in the presence of a varying feedback loop gain.
  • an adjustable gain mechanism such as an analog variable gain amplifier or mixed-signal multiplying digital-to-analog controller
  • the present invention offers significant advantages over similar existing harmonic feedforward and feedback systems.
  • the present invention utilizes a tracking sensor which has considerably less information constraints or requirements when compared to those required for existing feedforward and/or harmonic synthesis methods.
  • This invention also offers advantages over feedforward methods due to the fact that feedback control can respond nearly instantaneously to gain variations.
  • Pure harmonic approaches, such as harmonic synthesis also assume pure tones within the disturbance spectra.
  • Rotating machinery periodic disturbances are typically accompanied by lesser magnitude secondary sideband components which are offset slightly in frequency from the primary disturbance due to system non-linearity and, often, variances in frequency about the dominant frequency. These additional or locally transient components, which would lie within the feedback attenuation bands, would be naturally attenuated.
  • FIG. 1 shows a schematic block diagram of the present noise and vibration control system.
  • FIG. 2 is a schematic block diagram of the proposed control system.
  • FIG. 3 is a graph showing the in-cabin power spectrum of noise from a propeller-driven aircraft, indicating that narrow-band frequencies dominate the overall noise level.
  • FIG. 4 is a block diagram of a virtual center frequency generator.
  • FIG. 5 is a block diagram of one example of a commercially available externally controlled center-frequency bandpass filter.
  • FIG. 6 is a block diagram of one example of a commercially available externally controlled allpass filter for fixed or tracking phase compensation.
  • FIG. 7 is a block diagram of a microprocessor controlled gain block for scheduled gain adjustment of feedback loop gain based on disturbance frequencies.
  • FIG. 8 shows the disturbance spectrum for a small prop aircraft with the present invention off and on.
  • FIG. 1 shows an overall schematic diagram of the present system.
  • a region 1 e.g., a structure or an enclosed region of space
  • a vibration or noise source 2 e.g., vehicle engine vibration, aircraft jet engine noise, propeller air-rush noise, generator noise, vibration of a compressor in an appliance, or noise from an electric transformer
  • the vibration source 2 can generate narrow-band or broadband excitations, including noise, vibrations, or acoustic energy.
  • the present invention can be combined, if necessary, with other control algorithms 9, e.g. pseudo-feedforward control, through an adder 15.
  • the resulting control signal is sent to the actuators 13.
  • the narrow band feedback controller includes a virtual center frequency generator 4 , as shown in greater detail in FIG. 4.
  • the vibration source 2 also excites a pseudo-excitation sensor 3 (e.g. , a microphone or an accelerometer at or near the vibration source 2) that receives an acoustic or vibratory signal and outputs an analog electrical signal to a bandpass filter 10 which isolates the frequency of the fundamental excitation, as depicted in FIG. 4.
  • a frequency sensor, or wave measuring sensor could be substituted.
  • the resulting output signal from the bandpass filter 10 is sent through a zero-crossing detector 11 which converts the analog signal into a digital pulse train. These pulse trains are sent to a phase-locked loop 12 for frequency amplification to match the required center frequency of the filter.
  • the resulting frequency-amplified pulse trains are sent to the bandpass filter 6 which operates based on a switched capacitor filter, as shown in FIG. 5.
  • the bandpass filter 6 can be a CMOS active filter driven by the clock pulses generated by the phase-locked loop 12 and controlled by a combination of resistors.
  • This universal monolithic filter has three output pins that allow configuration of all-pass, high-pass, low-pass, and bandpass filters. The center frequency of these filters can be adapted to a desired frequency by means of the input clock frequency.
  • the all-pass filters 7 have full- spectrum unity gain and a frequency-dependent phase characteristics.
  • Switch-capacitor all-pass filters have programmable filter quality (Q) , which determines the steepness of the phase curve and a controlling clock input as described for the bandpass switched capacitor filter.
  • phase curve roll off and/or input clock frequency and clock ratio are chosen appropriately, then the delay of the passband will be appropriate to cause a net 180 degree phase shift at the center of the narrow passband being excited by the vibration source 2. Resulting signals from the all-pass filters 7 are sent to gain control mechanisms and summed for output.
  • the bandpassed feedback signals are passed through digitally controlled allpass filters and/or digitally controlled gain blocks prior to feedback summation.
  • a fixed frequency allpass filter can be used for phase compensation.
  • the disturbance frequency detection sensor signal is used to determine the disturbance frequency or frequencies present and that information is used to set the digitally controlled allpass filter or tapped delay line to the phase shift appropriate for that disturbance filtering. If scheduled phase compensation is used, the phase schedule is determined from the feedback loop transfer function estimate. Otherwise, on-line phase adaptation is used.
  • Digitally controlled phase compensation can be accomplished by either controlling the clock input frequency to a fixed clock ration switched capacitor filter or by controlling the clock ratio and Q on a microprocessor-programmable allpass filter.
  • the output of the allpass filter is fed into a microprocessor-controlled gain block.
  • the block diagram of such a device comprised of a multiplying digital-to-analog converter is shown in FIG. 7 although other functionally equivalent implementations are possible.
  • the objective is to perform multiples of narrow-band frequency excitations (e.g. for excitation sources having a series of narrow peaks as illustrated in FIG. 3) , so the control output from the narrow band controller 5 should be sent to the actuators 13 for input to the excited region 1.
  • phase-locked loop As shown in FIG. 4, a main component of the virtual center frequency generator is a phase-locked loop.
  • Phase-locked loops have a variety of configurations and usage including extracting periodic signals, digital or analog frequency multiplication (known as frequency synthesis) , and tone generation.
  • the phase-locked loop 12 in this invention is used as a frequency synthesizer to multiply the frequency of the disturbance by a value corresponding to the clock ratio of the filters to create a mechanism by which the disturbance directly controls the center frequency of the disturbance isolation filters.
  • the narrowband feedback controller operates as a direct analog to a feedforward notch filter.
  • the resulting transfer function of the operation is: 1 - H(s) where H(s) is the transfer function of the bandpass filter.
  • H(s) is the transfer function of the bandpass filter.
  • H' (s) is a controller in the feedback loop of the resulting closed-loop system. Solving for H' (s) yields the ideal feedback controller for disturbance rejection to be:
  • phase compensation is required when the acoustic or vibration sensor and actuator dynamics are significant and decoupled from the plant. Still, because the control effort is isolated to a few distinct frequencies across the disturbance range at any one instance in time, the phase compensation is only necessary for those few frequencies. This results in the simple addition of a phase compensation device such as an tuned allpass filter or a tapped delay line with an appropriate sample frequency and buffer length.
  • this invention presents an active noise and vibration control system that:

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

Abstract

Système de commande qui fournit une atténuation active des excitations à une région ou structure (1). Un détecteur de rétroaction (14) génère un signal en réponse à des excitations de la région (1), qui est envoyé à un dispositif de commande (5) de rétroaction à bande étroite doté d'un détecteur (4) de fréquences, d'un filtre passe-bande (6) commandé par le détecteur (4) de fréquences, et un générateur (8) de commande de rétroaction. Le détecteur de fréquences (4) détermine la fréquence maximale des excitations. Un filtre passe-bande (6) ne laisse passer que les signaux provenant du détecteur (14) de rétroaction dans une bande de fréquence étroite régulée par le détecteur (4) de fréquences. Le générateur (8) de commande de rétroaction reçoit le signal filtré du filtre passe-bande (6) et produit un signal de sortie de commande utilisé par un actionneur (13) pour atténuer les excitations. Plusieurs filtres passe-bande (6) peuvent être utilisés en parallèle pour atténuer plusieurs bandes de fréquence si la source d'excitation possède une pluralité de valeurs maximales. Cette configuration permet aux bandes de se déplacer sur le spectre des fréquences en réponse aux excitations.
PCT/US1997/009527 1996-06-05 1997-06-03 Systeme actif de commande de retroaction pour rejet des perturbations a bande etroite transitoire sur une large plage spectrale Ceased WO1997046176A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP97927930A EP0904035A4 (fr) 1996-06-05 1997-06-03 Systeme actif de commande de retroaction pour rejet des perturbations a bande etroite transitoire sur une large plage spectrale

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1916696P 1996-06-05 1996-06-05
US60/019,166 1996-06-05

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WO1997046176A1 true WO1997046176A1 (fr) 1997-12-11

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CN108646598A (zh) * 2018-05-04 2018-10-12 南京大学 一种适于小型化的低阶模拟反馈控制器及其设计方法
WO2019084480A1 (fr) * 2017-10-26 2019-05-02 Bose Corporation Suppression adaptative du bruit de retour d'une perturbation sinusoïdale
WO2019213503A1 (fr) * 2018-05-04 2019-11-07 Andersen Corporation Ciblage de fréquence multibande pour atténuation de bruit
US11335312B2 (en) 2016-11-08 2022-05-17 Andersen Corporation Active noise cancellation systems and methods

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11335312B2 (en) 2016-11-08 2022-05-17 Andersen Corporation Active noise cancellation systems and methods
WO2019084480A1 (fr) * 2017-10-26 2019-05-02 Bose Corporation Suppression adaptative du bruit de retour d'une perturbation sinusoïdale
US10721561B2 (en) 2017-10-26 2020-07-21 Bose Corporation Adaptive feedback noise cancellation of a sinusoidal disturbance
CN108646598A (zh) * 2018-05-04 2018-10-12 南京大学 一种适于小型化的低阶模拟反馈控制器及其设计方法
WO2019213503A1 (fr) * 2018-05-04 2019-11-07 Andersen Corporation Ciblage de fréquence multibande pour atténuation de bruit
US10916234B2 (en) 2018-05-04 2021-02-09 Andersen Corporation Multiband frequency targeting for noise attenuation
CN112384973A (zh) * 2018-05-04 2021-02-19 安德森公司 针对噪声衰减的多频带频率
US11417308B2 (en) 2018-05-04 2022-08-16 Andersen Corporation Multiband frequency targeting for noise attenuation

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EP0904035A1 (fr) 1999-03-31
CA2247808A1 (fr) 1997-12-11
EP0904035A4 (fr) 1999-09-29

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