5152025303540455055DescriptionTECHNICAL FIELD[0001] The present invention relatesto an active vibration noise controller that performs controls to reduce noise owingto mutual interference by outputting secondary sound for canceling noise occurring in an environment such as in thecabin ofan automobile or aircraft.BACKGROUND ART[0002] Japanese Patent Unexamined Publication No. 2005-084500 disclosesa conventional active vibration noisecontroller that is equipped with multiple speakers asa secondary sound generator, and microphones asan errorsignaldetector, in an enclosed space such as in an automobile cabin; and suppresses noise ata position spaced from themicrophones, usinga compensating filter to actively reduce noise ata simulated evaluation point.[0003] The conventional apparatus uses multiple speakers 11, 12 asa secondary sound generator, as shown in Fig.4. The filter coefficient of adaptive filter 14 is successively updated so as to minimize an error signal detected bymicrophone 13asan evaluation point, owing tothe secondary sound from speaker 11 atthe front seatand from speaker12 atthe rear seat, allowing optimal performance of vibration noise suppression to be achieved atan evaluation point.[0004] Further, the filter coefficient of compensating filter 15 is determined according to the ratio ofthe transmissioncharacteristic from speaker 11 atthe front seat toa simulatedevaluation point positioned where is spacedfrommicrophone13; to the transmission characteristic from speaker 12 atthe rear seattothe simulated evaluation point. Consequently,atthe simulated evaluation point atthe rear seat, secondary sound from speaker 11 atthe front seatcan be cancelledby that from speaker 12 atthe rear seat, and thus speaker 11 atthe front seat suppresses vibration or noise occurringatthe simulated evaluation point atthe rear seat.[0005] However, secondary sound supplied from speaker 12 at the rear seat through compensating filter 15 onlycancelsthe effect ofan output signal from speaker 11 atthe front seaton the simulated evaluation point, atthe simulatedevaluation point. That is, atthe simulated evaluation point, residual vibration noise, namelyan error signal, is not detecteddue to absence of an error signal detector suchasa microphone, and thus noise change is not followed atthe simulatedevaluation point. Consequently, effective noise reduction is not achieved at the simulated evaluation point when thetransmission characteristic from the speaker to the simulated evaluation point changes due tochanges ofthe speakercharacteristic or to opening/closing ofa window.SUMMARYOFTHE INVENTION[0006] An active vibration noise controller of the present invention is composed ofa reference signal generator thatgeneratesa harmonic reference signal selected fromthe frequencies of noise occurred froma noise source ofan engineorthe like;a first adaptive filter that outputsa first control signal according tothe reference signal;a second adaptivefilter that outputsa second control signal according to the reference signal;a first secondary sound generator thatgenerates secondary sound for canceling noise according tothe first control signal;a second secondary sound generatorthat generates secondary sound for canceling noise according tothe second control signal; first and second errorsignaldetectors that detect the result of interference beMeen the secondary sound andthe noise;a first correction filter thatprocessesthe reference signal usinga characteristic simulating the transmission characteristic fromthe first secondarysound generator to the first error signal detector, and outputsa first referencing signal;a second correction filter thatprocesses the reference signal usinga characteristic simulating the transmission characteristic from the second sec-ondary sound generator tothe second error signal detector, and outputsa second referencing signal;a first filtercoefficientupdater that updates the coefficient ofthe first adaptive filter according tothe first referencing signal and the errorsignalfrom the first error signal detector; and a second filter coefficient updater that updates the coefficient of the secondadaptive filter according to the second referencing signal and the error signal fromthe second error signal detector. Theactive vibration noise controller is further equipped with first and second compensating filters that correct firstand secondcontrol signals with respective filter coefficients, and output first and second compensating signals, respectively. Thefirst secondary sound generator outputsa sum ofthe first control signal supplied from the first adaptive filter, and thesecond compensating signal that is supplied fromthe second adaptive filterand is corrected by the second compensatingfilter. The second secondary sound generator outputsa sum of the second control signal supplied from the secondadaptive filter, and the first compensating signal that is supplied fromthe first adaptive filter and is corrected by the firstcompensating filter. The filter coefficient ofthe first compensating filter is determined according tothe ratio ofthe trans-mission characteristic fromthe first secondary sound generatortothe second error signal detector; to the transmissioncharacteristic from the second secondary sound generator to the second error signal detector. The filter coefficient ofthe second compensating filter is determined according to the ratio of the transmission characteristic from the second2
