Vibration/noise control system for vehicles

In a vibration/noise control system for a vehicle having a chassis, a compartment, and a power plant for driving said vehicle, periodic or semi-periodic vibrations and noises being generated from at least one vibration/noise source including said power plant, arranged at at least one predetermined location on said chassis or in said compartment, the system including:

• first filter means for generating a control signal for changing a transfer characteristic of at least one vibration/noise-transmitting path formed between said at least one source and said at least one predetermined location by filtering a predetermined input signal supplied thereto, said first filter means having a filter coefficient on which it operates;
• driving signal-forming means for converting said control signal into a driving signal;
• electromechanical transducer means responsive to said driving signal for controlling said vibrations and noises;
• error signal-forming means for forming an error signal indicative of residual vibrations and noises remaining after said vibrations and noises have been reduced by an output from said at least one electromechanical transducer means through addition of vectors;
• second filter means for representing a transfer characteristic of a vibration/noise-transmitting path formed between said driving signal-forming means and said error signal-forming means, and generating a reference signal;
• and
• control signal-renewing means for renewing said filter coefficient of said first filter means such that said error signal assumes the minimum value, based on said error signal, said reference signal from said second filter means, and said filter coefficient of said first filter means;
• the improvement wherein said error signal-forming means comprises a plurality of error signal-forming means arranged at a plurality of predetermined locations as said at least one predetermined location for generating respective error signals corresponding, respectively, to said predetermined locations, said vibration/noise control system including operating condition-detecting means for detecting operating conditions of said power plant, and weighing means for weighing said error signals in dependence on said operating conditions of said power plant detected by said operating condition-detecting means.

In a vibration/noise control system for a vehicle having a chassis, a compartment, and a power plant for driving said vehicle, periodic or semi-periodic vibrations and noises being generated from at least one vibration/noise source including said power plant, arranged at least one predetermined location on said chassis or in said compartment, the system including:

• first filter means for generating a control signal for changing a transfer characteristic of at least one vibration/noise-transmitting path formed between said at least one source and said at least one predetermined location by filtering a predetermined input signal supplied thereto, said first filter means having a filter coefficient on which it operates;
• driving signal-forming means for converting said control signal into a driving signal;
• electromechanical transducer means responsive to said driving signal for controlling said vibrations and noises;
• error signal-forming means for forming an error signal indicative of residual vibrations and noises remaining after said vibrations and noises have been reduced by an output from said at least one electromechanical transducer means through addition of vectors;
• second filter means for representing a transfer characteristic of a vibration/noise-transmitting path formed between said driving signal-forming means and said error signal-forming means, and generating a reference signal;
• and
• control signal-renewing means for renewing said filter coefficient of said first filter means such that said error signal assumes the minimum value, based on said error signal, said reference signal from said second filter means, and said filter coefficient of said first filter means;
• the improvement comprising:
• first driving repetition period signal-forming means for forming a first pulse signal indicative of a driving repetition period of said at least one vibration/noise source per a predetermined very small angle;
• second driving repetition period signal-forming means for dividing said first pulse signal to form a plurality of kinds of second pulse signals which are synchronous, respectively, with repetition periods of components of said vibrations and noises inherent to respective component parts of said at least one vibration/noise source;
• sampling interval-determining means for determining a sampling interval governing sequential operations of outputting and renewing said filter coefficient of said first filter means, based upon timing of detection of the first pulse signal detected by the first driving repetition period signal-forming means;
• transfer characteristic-correcting means for correcting a transfer characteristic of said second filter means according to said sampling interval determined by said sampling interval-determining means;
• memory means for storing said transfer characteristic of said second filter means corrected by said transfer characteristic-correcting means;
• means for setting a tap length of said first filter means to a value substantially equal to a ratio of a frequency of said second pulse signal to a frequency of said first pulse signal;
• said first filter means having a plurality of adaptive digital filters, and said second filter means having a plurality of correcting digital filters corresponding, respectively, to said adaptive digital filters;
• and
• means for supplying said second pulse signals formed by said second driving repetition period signal-forming means, as said predetermined input signal, respectively, to said adaptive digital filters and said correction digital filters.

In a vibration/noise control system for a vehicle having a chassis, a compartment, and a power plant for driving said vehicle, periodic or semi-periodic vibrations and noises being generated from a vibration/noise source including at least said power plant, arranged at at least one predetermined location on said chassis or in said compartment, the system including:

• first filter means for generating a control signal for changing a transfer characteristic of at least one vibration/noise-transmitting path formed between said at least one source and said at least one predetermined location by filtering a predetermined input signal supplied thereto, said first filter means having a filter coefficient on which it operates;
• driving signal-forming means for converting said control signal into a driving signal;
• electromechanical transducer means responsive to said driving signal for controlling said vibrations and noises;
• error signal-forming means for forming an error signal indicative of residual vibrations and noises remaining after said vibrations and noises have been reduced by an output from said at least one electromechanical transducer means through addition of vectors;
• second filter means for representing a transfer characteristic of a vibration/noise-transmitting path formed between said driving signal-forming means and said error signal-forming means, and generating a reference signal;
• and
• control signal-renewing means for renewing said filter coefficient of said first filter means such that said error signal assumes the minimum value, based on laid error signal, said reference signal from said second filter means, and said filter coefficient of said first filter means;
• the improvement comprising:
• first driving repetition period signal-forming means for forming a first pulse signal indicative of a driving repetition period of said power plant per a predetermined very small angle;
• second driving repetition period signal-forming means for dividing said first pulse signal to form a plurality of kinds of second pulse signals which are synchronous, respectively, with repetition periods of components of said vibrations and noises generated from respective component parts of said power plant and inherent to said power plant;
• random signal-generating means for a random signal having a small amplitude which is superposed on said control signal from said first filter means;
• and
• sampling interval-determining means for determining a sampling interval governing sequential operations of outputting and renewing said filter coefficient of said first filter means;
• said second filter means comprising:
• periodic signal component-eliminating means for forming a residual component signal by eliminating a periodic signal component ascribed to said power plant which is large in amplitude from said error signal formed by said error signal-forming means;
• transfer characteristic-determining means for determining a transfer characteristic of a path through which said vibrations and noises are transmitted, based on said random signal generated by said random signal-generating means, said residual component signal formed by said periodic signal component-eliminating means, and said filter coefficient of said second filter means;
• and
• memory means for storing said transfer characteristic determined by said transfer characteristic-determining means.

A vibration/noise control system according to 31, including point number-calculating means for calculating a point number indicative of a ratio of a repetition period of a component of said vibrations and noises to a sampling interval determined by said sampling frequency, based on said time interval between adjacent pulses of each of said second pulse signals and said sampling interval, equalizing means for making the number of taps of said first filter means equal to said point number calculated by said point number-calculating means;

• and
• wherein said pseudo-period train-forming means comprises first pseudo-period train-forming means for forming a first pseudo-period train of said filter coefficient of said second filter means, when said point number is smaller than the number of taps of said second filter means, by the use of the following equation:
• ##EQU4## where C represents said pseudo-period train, C.LAMBDA. said filter coefficient of said second filter means, J the number of taps of said second filter means, N said point number, and JdivN an integer obtained from J/N by omitting fractions of J/N, and
• second pseudo-period train-forming means for forming a second pseudo-period train of said filter coefficient of said second filter means, when said point number is larger than the number of taps of said second filter means, by the use of the following equation:
• C.about.=[C.LAMBDA.j Cj=0, 1, . . . , J-1), 0, . . . 0]
• where the number of 0 in (0, . . . , 0) is equal to N-J;
• and
• reference signal-forming means for forming a reference signal based on said first or second pseudo-period trains of said filter coefficient of said second filter means formed by said first or second pseudo-period train-forming means.