VEHICULAR ACTIVE NOISE CONTROL SYSTEM
First Claim
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1. A vehicular active noise control system, comprising:
- a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle;
an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal;
a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment;
an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound;
a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal;
a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal;
a vehicle speed detector for detecting a vehicle speed of said vehicle and outputting a vehicle speed signal representing said detected vehicle speed; and
a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said vehicle speed signal, and outputting said calculated control frequency to said basic signal generator;
wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event.
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Abstract
A frequency detecting circuit estimates the frequency fp of a propeller shaft based on the frequency fc of vehicle speed pulses, and calculates a control frequency fp′ which is a harmonic of the frequency fp. A basic signal generator generates a basic cosine wave signal xp1 and a basic sine wave signal xp2 of the control frequency fp′. Adaptive filters and an adder generate a control signal Scp for canceling a driveline noise produced in a passenger compartment by the propeller shaft. A speaker outputs a canceling sound based on the control signal Scp into the passenger compartment.
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Citations
14 Claims
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1. A vehicular active noise control system, comprising:
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a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle; an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal; a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment; an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound; a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal; a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal; a vehicle speed detector for detecting a vehicle speed of said vehicle and outputting a vehicle speed signal representing said detected vehicle speed; and a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said vehicle speed signal, and outputting said calculated control frequency to said basic signal generator; wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event. - View Dependent Claims (4, 5, 9, 10, 11, 12, 13, 14)
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2. A vehicular active noise control system, comprising:
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a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle; an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal; a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment; an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound; a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal; a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal; an engine rotational speed detector for detecting an engine rotational speed of an engine of said vehicle; and a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said engine rotational speed, and outputting said calculated control frequency to said basic signal generator; wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event. - View Dependent Claims (6, 7, 8)
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3. A vehicular active noise control system, comprising:
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a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle; an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal; a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment; an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound; a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal; a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal; a vehicle speed detector for detecting a vehicle speed of said vehicle and outputting a vehicle speed signal representing said detected vehicle speed; an engine rotational speed detector for detecting an engine rotational speed of an engine of said vehicle; and a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said vehicle speed signal or said engine rotational speed, and outputting said calculated control frequency to said basic signal generator; wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event.
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Specification