Active vibration control
First Claim
1. An active vibration control system for reducing, by the generation of secondary vibrations, the vibration generated in a vibration field by a primary source of vibration, comprisinga) a processing means having an error signal input, a reference signal input, and a drive signal output;
- b) said processing means having means to generate at said drive signal output at least one drive signal in response to a reference signal;
c) a plurality M of spaced-apart secondary vibration sources for generating said secondary vibrations in said vibration field;
d) means to connect said secondary sources to the drive signal output of the processing means, said means including a first low-pass filter means provided for filtering said at least one drive signal output from said processing means, said first low pass filter means having a fixed cut-off frequency;
e) reference signal generating means responsive to said primary source to generate at least one reference signal representing at least one selected harmonic of said primary source of vibration;
f) means to connect said reference signal generating means to the reference signal input of the processor means;
g) a plurality L, L>
M, of spaced apart sensor means at a plurality of locations in said vibration field by said primary and secondary sources, and operative to output error signals in response to detection of vibrations from said primary and secondary sources;
h) means to connect said sensor means with said error signal input of said processing means, said means including a second low-pass filter means provided for filtering said error signals input to said processing means, said second low-pass filter means having a fixed cut-off frequency;
i) a sample rate oscillator for providing a constant sample rate signal;
j) means to supply said sample rate signal to said processing means to enable said processing means to sample the reference and error signals at a constant sampling rate;
k) said processing means comprising a plurality of adaptive response filters having first filter coefficients and second filter coefficients,I) said first filter coefficients to model the phase and amplitude response of said sensor means to the output of said secondary vibration sources over a wide range of frequencies,II) said second filter coefficients being determined in accordance with an algorithm in response to the sampled values of the error signals as filtered by said second low-pass filter means; and
l) said processing means being operative to provide said drive signal, using said first and second filter coefficients, to reduce the amplitude of vibrations sensed by said sensor means.
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Accused Products
Abstract
To reduce noise inside a motor car passenger compartment, two loudspeakers 371, 372 are driven by signals derived from a reference signal x(n) by adaptive filtering carried out by a programmed microprocessor and memory unit 36 which adapts the filtering in dependence on error signals el (n) from four microphones 421, 422, 423 and 424 distributed in the passenger compartment. Reference filtering coefficients are initially determined by analysis of finite impulse responses when white noise is acoustically coupled from the loudspeakers 37 to the microphones 42, a white noise generator 48 being coupled to the unit 36. The reference signal x(n) is restricted to one or more selected harmonics or subharmonics of the fundamental noise frequency by a filter 34 which tracks the selected frequency. The selected frequency may be obtained from a coil 31 in the ignition circuit of the vehicle.
108 Citations
23 Claims
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1. An active vibration control system for reducing, by the generation of secondary vibrations, the vibration generated in a vibration field by a primary source of vibration, comprising
a) a processing means having an error signal input, a reference signal input, and a drive signal output; -
b) said processing means having means to generate at said drive signal output at least one drive signal in response to a reference signal; c) a plurality M of spaced-apart secondary vibration sources for generating said secondary vibrations in said vibration field; d) means to connect said secondary sources to the drive signal output of the processing means, said means including a first low-pass filter means provided for filtering said at least one drive signal output from said processing means, said first low pass filter means having a fixed cut-off frequency; e) reference signal generating means responsive to said primary source to generate at least one reference signal representing at least one selected harmonic of said primary source of vibration; f) means to connect said reference signal generating means to the reference signal input of the processor means; g) a plurality L, L>
M, of spaced apart sensor means at a plurality of locations in said vibration field by said primary and secondary sources, and operative to output error signals in response to detection of vibrations from said primary and secondary sources;h) means to connect said sensor means with said error signal input of said processing means, said means including a second low-pass filter means provided for filtering said error signals input to said processing means, said second low-pass filter means having a fixed cut-off frequency; i) a sample rate oscillator for providing a constant sample rate signal; j) means to supply said sample rate signal to said processing means to enable said processing means to sample the reference and error signals at a constant sampling rate; k) said processing means comprising a plurality of adaptive response filters having first filter coefficients and second filter coefficients, I) said first filter coefficients to model the phase and amplitude response of said sensor means to the output of said secondary vibration sources over a wide range of frequencies, II) said second filter coefficients being determined in accordance with an algorithm in response to the sampled values of the error signals as filtered by said second low-pass filter means; and l) said processing means being operative to provide said drive signal, using said first and second filter coefficients, to reduce the amplitude of vibrations sensed by said sensor means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An active vibration control system for reducing, by the generation of secondary vibrations, the vibration generated in a vibration field by a primary source of vibration, comprising
a) a processing means having an error signal input, a reference signal input, and a drive signal output; -
b) said processing means having means to generate at said drive signal output at least one drive signal in response to a reference signal; c) a plurality M of spaced-apart secondary vibration sources for generating said secondary vibrations in said vibration field; d) means to connect said secondary sources to the drive signal output of the processing means, said means including a first low-pass filter means provided for filtering said at least one drive signal output from said processing means, said first low pass filter means having a fixed cut-off frequency; e) reference signal generating means responsive to said primary source to generate at least one reference signal representing at least one selected harmonic of said primary source of vibration; f) means to connect said reference signal generating means to the reference signal input of the processor means; g) a plurality L, of spaced apart sensor means at a plurality of locations in said vibration field generated by said primary and secondary sources, and operative to output error signals in response to detection of vibrations from said primary and secondary sources; h) means to connect said sensor means with said error signal input of said processing means, said means including a second low-pass filter means provided for filtering said error signals input to said processing means, said second low-pass filter means having a fixed cut-off frequency; i) a sample rate oscillator for providing a constant sample rate signal; j) means to supply said sample rate signal to said processing means to enable said processing means to sample the reference and error signals at a constant sampling rate; k) said processing means comprising a plurality of adaptive response filters having first filter coefficients and second filter coefficients, I) said first filter coefficients to model the phase and amplitude response of said sensor means to the output of said secondary vibration sources over a wide range of frequencies, II) said second filter coefficients being determined in accordance with an algorithm in response to the sampled values of the error signals as filtered by said second low-pass filter means, said algorithm being arranged to minimise a cost function; and l) said processing means being operative to provide said drive signal, using said first and second filter coefficients, to reduce the amplitude of vibrations sensed by said sensor means.
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Specification