JP2019082628A - Active noise reduction device, vehicle, and, abnormality determination method - Google Patents

Abstract

To provide an active noise reduction device capable of detecting abnormality of a reference signal source.SOLUTION: The active noise reduction device 10 is an active noise reduction device which reduces noise N0 in a space in a vehicle 50. The active noise reduction device 10 includes a first reference signal input terminal 11 to which a first reference signal having a correlation with the noise N0 output by a first reference signal source 51 attached to the vehicle 50 is input, a first signal processing unit 14 which generates a cancellation signal used for outputting the cancellation sound N1 for reducing the noise N0 using the input first reference signal, and a detection unit 20 which detects a DC offset of the input first reference signal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an active noise reduction device that actively reduces noise by making the noise interfere with cancellation noise, a vehicle including the same, and an abnormality determination method.

  Conventionally, noise is generated by outputting a cancellation sound for canceling noise from a cancellation sound source using a reference signal having a correlation with noise and an error signal based on a residual sound interfered with the noise and cancellation sound in a predetermined space. An active noise reduction device which actively reduces is known (for example, refer to patent documents 1). The active noise reduction device generates a cancellation signal for outputting a cancellation sound using an adaptive filter so that the sum of squares of the error signal is minimized.

Patent No. 3551653 gazette

  By the way, in the active noise reduction device, noise may not be properly reduced due to the occurrence of an abnormality in peripheral devices.

  The present invention provides an active noise reduction device and the like capable of detecting an abnormality in a reference signal source.

  An active noise reduction device according to one aspect of the present invention is an active noise reduction device that reduces noise in a space in a vehicle, and is correlated with the noise that is output by a first reference signal source attached to the vehicle. And a signal processing unit for generating a cancellation signal used for outputting a cancellation sound for reducing the noise using the first input unit to which the first reference signal having the signal is input and the inputted first reference signal And a detection unit that detects a DC (Direct Current) offset of the input first reference signal.

  An active noise reduction device according to one aspect of the present invention is an active noise reduction device that reduces noise in a space in a vehicle, and is correlated with the noise that is output by a first reference signal source attached to the vehicle. And a signal processing unit for generating a cancellation signal used for outputting a cancellation sound for reducing the noise using the first input unit to which the first reference signal having the signal is input and the inputted first reference signal And an error signal input unit to which an error signal corresponding to a residual sound due to the interference between the cancellation sound and the noise is input, and a detection unit which detects a DC offset of the input error signal.

  A vehicle according to an aspect of the present invention includes the active noise reduction device and the first reference signal source.

  An abnormality determination method according to an aspect of the present invention is an abnormality determination method executed by an active noise reduction device that reduces noise in a space in a vehicle, and is output by a first reference signal source attached to the vehicle Acquiring a first reference signal having a correlation with the noise, and using the acquired first reference signal to generate and acquire a cancellation signal used for outputting a cancellation sound for reducing the noise A DC offset of the first reference signal is detected, and a signal indicating abnormality of the first reference signal source is output based on a detection result of the DC offset of the first reference signal.

  The active noise reduction device and the like of the present invention can detect an abnormality of the reference signal source.

FIG. 1 is a schematic view of a vehicle provided with the active noise reduction device according to the first embodiment as viewed from above. FIG. 2 is a block diagram showing a functional configuration of the active noise reduction device according to the first embodiment. FIG. 3 is a flowchart of the basic operation of the active noise reduction device according to the first embodiment. FIG. 4 is a diagram showing a detailed configuration of the detection unit according to the first embodiment. FIG. 5 is a flowchart of the abnormality determination operation of the abnormality determination unit according to the first embodiment. FIG. 6 is a schematic view of a vehicle provided with the active noise reduction device according to the second embodiment as viewed from above. FIG. 7 is a block diagram showing a functional configuration of the active noise reduction device according to the second embodiment. FIG. 8 is a diagram showing a detailed configuration of the detection unit according to the second embodiment. FIG. 9 is a flowchart of the abnormality determination operation of the abnormality determination unit according to the second embodiment. FIG. 10 is a view showing an arrangement example of the reference signal source and the cancellation sound source.

  Embodiments will be specifically described below with reference to the drawings. The embodiments described below are all inclusive or specific examples. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and the present invention is not limited thereto. Further, among the components in the following embodiments, components not described in the independent claim indicating the highest concept are described as arbitrary components.

  Further, each drawing is a schematic view, and is not necessarily illustrated exactly. In the drawings, substantially the same components are denoted by the same reference numerals, and redundant description may be omitted or simplified.

Embodiment 1
[Configuration of Vehicle Equipped with Active Noise Reduction Device]
In the first embodiment, an active noise reduction device mounted on a vehicle will be described. FIG. 1 is a schematic view of a vehicle provided with the active noise reduction device according to the first embodiment as viewed from the top side.

  The vehicle 50 is an example of a mobile device, and the active noise reduction device 10 according to the first embodiment, the first reference signal source 51, the cancellation sound source 52, the error signal source 53, and the vehicle main body 54 And a vehicle control unit 55. The vehicle 50 is specifically an automobile, but is not particularly limited.

  The first reference signal source 51 is a transducer that outputs a first reference signal that has a correlation with the noise in the space 57 of the vehicle cabin of the vehicle 50. In the first embodiment, the first reference signal source 51 is an acceleration sensor, and is disposed outside the predetermined space 57. Specifically, the first reference signal source 51 is attached to a sub-frame near the right front wheel (or a tire house of the right front wheel). The mounting position of the first reference signal source 51 is not particularly limited. Further, the first reference signal source 51 may be a microphone.

  The cancellation sound source 52 outputs a cancellation sound to a predetermined space using a cancellation signal. In the first embodiment, although the cancellation sound source 52 is a speaker, the cancellation sound is output when a part of the structure of the vehicle 50 (for example, a sunroof etc.) is vibrated by a drive mechanism such as an actuator. It is also good. Further, in the active noise reduction device 10, a plurality of cancellation sound sources 52 may be used, and the position of the cancellation sound source 52 is not particularly limited.

  The error signal source 53 detects a residual sound obtained by interference between noise and cancellation sound in the space 57, and outputs an error signal based on the residual sound. The error signal source 53 is a transducer such as a microphone, and is preferably installed in the space 57 such as a head liner. The vehicle 50 may include a plurality of error signal sources 53.

  The vehicle body 54 is a structure configured of a chassis, a body, and the like of the vehicle 50. The vehicle body 54 forms a space 57 (in-vehicle space) in which the cancellation sound source 52 and the error signal source 53 are disposed.

  The vehicle control unit 55 controls (drives) the vehicle 50 based on the operation of the driver of the vehicle 50 or the like. The vehicle control unit 55 is, for example, an ECU (Electronic Control Unit), and is specifically realized by a processor, a microcomputer, a dedicated circuit, or the like. The vehicle control unit 55 may be realized by a combination of two or more of a processor, a microcomputer, and a dedicated circuit.

[Configuration of Active Noise Reduction Device]
Next, the configuration of the active noise reduction device 10 will be described. FIG. 2 is a block diagram showing a functional configuration of the active noise reduction device 10. As shown in FIG.

  As shown in FIG. 2, the active noise reduction device 10 includes a first reference signal input terminal 11, a cancel signal output terminal 12, an error signal input terminal 13, a first signal processing unit 14, and a storage unit 18. And a first input I / F unit 19, a detection unit 20, and a notification signal output terminal 21. I / F is an abbreviation of interface. The first signal processing unit 14 includes an adaptive filter unit 15, a simulated acoustic transfer characteristic filter unit 16, and a filter coefficient updating unit 17. The first signal processing unit 14 is realized by, for example, a processor such as a DSP (Digital Signal Processor), but may be realized by a microcomputer or a dedicated circuit and a combination thereof.

[basic action]
As described above, the active noise reduction device 10 performs the noise reduction operation. First, the basic operation of the active noise reduction device 10 will be described with reference to FIG. 3 in addition to FIG. FIG. 3 is a flowchart of the basic operation of the active noise reduction device 10.

  First, a first reference signal having a correlation with the noise N0 is input from the first reference signal source 51 to the first reference signal input terminal 11 (S11). The first reference signal input terminal 11 is an example of a first input unit, and specifically, a terminal formed of metal or the like.

  Next, the first signal processing unit 14 uses the first reference signal input to the first reference signal input terminal 11 and processed by the first input I / F unit 19. Thus, the cancellation signal used to output the cancellation sound N1 for reducing the noise N0 is generated. Specifically, the adaptive filter unit 15 of the first signal processing unit 14 generates a cancellation signal by applying (multiplying) an adaptive filter to the first reference signal input to the first reference signal input terminal 11 (S12). The adaptive filter unit 15 is realized by a so-called FIR filter or IIR filter. The adaptive filter unit 15 outputs the generated cancel signal to the cancel signal output terminal 12. The cancellation signal is used to output a cancellation sound N1 for reducing the noise N0, and is output to the cancellation signal output terminal 12 (S13).

  The cancel signal output terminal 12 is an example of the cancel signal output unit, and is a terminal formed of metal or the like. The cancellation signal generated by the adaptive filter unit 15 is output to the cancellation signal output terminal 12.

  A cancellation sound source 52 is connected to the cancellation signal output terminal 12. Therefore, a cancellation signal is output to the cancellation sound source 52 via the cancellation signal output terminal 12. The cancellation sound source 52 outputs a cancellation sound N1 based on the cancellation signal.

  The error signal source 53 detects a residual sound due to the interference between the cancellation sound N1 generated from the cancellation sound source 52 and the noise N0 in response to the cancellation signal, and outputs an error signal corresponding to the residual sound. As a result, the error signal is input to the error signal input terminal 13 (S14). The error signal input terminal 13 is an example of an error signal input unit, and is a terminal formed of metal or the like.

  Next, the simulated acoustic transfer characteristic filter unit 16 generates a filtered reference signal in which the first reference signal is corrected by the simulated transfer characteristic simulating the acoustic transfer characteristic from the cancel signal output terminal 12 to the error signal input terminal 13 (S15) ). The simulated transfer characteristic is, for example, measured in advance in the space 57 and stored in the storage unit 18. The simulated transfer characteristic may be determined by an algorithm that does not use a predetermined value.

  The storage unit 18 is a storage device in which simulated transfer characteristics are stored. The storage unit 18 also stores coefficients of an adaptive filter described later. Specifically, storage unit 18 is realized by a semiconductor memory or the like. When the first signal processing unit 14 is realized by a processor such as a DSP, the storage unit 18 also stores a control program to be executed by the processor. The storage unit 18 may store other parameters used for signal processing performed by the first signal processing unit 14.

  The filter coefficient updating unit 17 sequentially updates the coefficient W of the adaptive filter based on the error signal and the generated filtered reference signal (S16).

  More specifically, the filter coefficient update unit 17 calculates the coefficient W of the adaptive filter so that the sum of squares of the error signal is minimized using the Least Mean Square (LMS) method, and the calculated coefficient of the adaptive filter Output to the adaptive filter unit 15. Also, the filter coefficient updating unit 17 sequentially updates the coefficients of the adaptive filter. Expressing the vector of the error signal as e and the vector of the filtered reference signal as R, the coefficient W of the adaptive filter is represented by the following (Equation 1). Here, n is a natural number and represents the n-th sample at the sampling period Ts. μ is a scalar quantity, which is a step size parameter that determines the update quantity of the coefficient W of the adaptive filter per sampling.

  The filter coefficient updating unit 17 may update the coefficient W of the adaptive filter by a method other than the LMS method.

[Abnormality judgment operation]
Next, the abnormality determination operation of the active noise reduction device 10 will be described. When the failure mode of the first reference signal source 51 includes a variation of DC (Direct Current) offset of the first reference signal, detecting a DC offset of the first reference signal detects an abnormality of the first reference signal source can do. For example, when the first reference signal source 51 is an acceleration sensor or the like, a short circuit occurs if the DC offset adheres to the power supply voltage, or a disconnection or a ground occurs if the DC offset adheres to the reference voltage (ground) It can be determined that When the first reference signal source 51 is a microphone or the like, short or open can be detected by detecting the DC offset of the first reference signal. The active noise reduction device 10 includes a detection unit 20 and a notification signal output terminal 21 as components for performing such an abnormality detection operation.

  The detection unit 20 detects a DC offset of the input first reference signal. The notification signal output terminal 21 is an example of a notification signal output unit, and the detection unit 20 is a terminal from which a signal indicating an abnormality of the first reference signal source 51 is output. The notification signal output terminal 21 is formed of metal or the like. The notification signal output terminal 21 is electrically connected to the vehicle control unit 55.

  Hereinafter, the detailed configuration of the detection unit 20 will be described. FIG. 4 is a diagram showing a detailed configuration of the detection unit 20. As shown in FIG. The detailed configuration of the first input I / F unit 19 is also illustrated in FIG. 4.

  The first input I / F unit 19 cuts a band unnecessary for noise reduction and converts the first reference signal input to the first reference signal input terminal 11 into a digital signal. Specifically, the first input I / F unit 19 extracts only a signal of a necessary band from the capacitive element 19a that cuts the DC offset of the input first reference signal, and the input first reference signal. It has a band pass filter 19 b and an AD converter 19 c that converts the first reference signal into a digital signal. By cutting the DC offset by the capacitive element 19a, the dynamic range can be secured, and the resolution of the digital signal output from the AD converter 19c can be improved. The capacitive element 19a may be included in the band pass filter 19b. The capacitive element 19a may be omitted, and the DC offset may be cut by a band pass filter.

  Thus, in the configuration in which the DC offset is cut in the first input I / F unit 19, the first signal processing unit 14 is the first reference signal input to the first reference signal input terminal 11, and A cancellation signal is generated using the first reference signal whose DC offset has been cut by the capacitive element 19a. Therefore, it is difficult for the first signal processing unit 14 to detect the DC offset of the first reference signal.

  Therefore, the detection unit 20 acquires the first reference signal directly from the first reference signal input terminal 11, and detects the DC offset of the acquired first reference signal. That is, the detection unit 20 detects the DC offset of the first reference signal input to the first reference signal input terminal 11 before the DC component is cut by the capacitive element 19a. The detection unit 20 can detect a DC offset while securing a dynamic range. The detection unit 20 also outputs a notification signal indicating an abnormality of the first reference signal source 51 based on the detection result of the DC offset.

  Specifically, the detection unit 20 includes a voltage dividing circuit 20a, an AD converter 20b, and an abnormality determination unit 20c.

  The voltage dividing circuit 20 a is a circuit that reduces the signal level of the first reference signal input to the first reference signal input terminal 11 by voltage division. The AD converter 20 b converts the first reference signal whose signal level has been reduced by the voltage dividing circuit 20 a into a digital signal. That is, the first reference signal is digitized. The voltage dividing circuit 20a is not an essential component and may be omitted.

  The abnormality determination unit 20 c monitors the digital value of the digitized first reference signal to determine an abnormality of the first reference signal source 51. The abnormality determination unit 20c is specifically realized by a microcomputer, but may be realized by a processor or a dedicated circuit. The abnormality determination unit 20c may be realized by a combination of two or more of a microcomputer, a processor, and a dedicated circuit. When the abnormality determination unit 20c operates by executing a control program, such a control program is stored in the storage unit 18. The storage unit 18 also stores determination conditions (for example, a predetermined time and a predetermined value described later) that the abnormality determination unit 20 c uses to determine the presence or absence of an abnormality.

  Hereinafter, the abnormality determination operation of the abnormality determination unit 20c will be described with reference to a flowchart. FIG. 5 is a flowchart of the abnormality determination operation of the abnormality determination unit 20c.

  First, the abnormality determination unit 20c acquires a digitized first reference signal from the AD converter 20b (S21). Next, the abnormality determination unit 20c detects a DC offset of the acquired first reference signal (S22). The abnormality determination unit 20 c detects the DC offset of the first reference signal, for example, by averaging the first reference signal. More specifically, the abnormality determination unit 20c performs an averaging process of digital values of the acquired first reference signal, and detects an average of the digital values as a DC offset of the first reference signal.

  Next, the abnormality determination unit 20c determines the abnormality of the first reference signal source 51 based on the detected DC offset. For example, when detecting an abnormality in which the DC offset is stuck to a positive power supply voltage, the abnormality determination unit 20c determines whether the detected DC offset exceeds a predetermined value for a predetermined time or more (S23).

  When it is determined that the DC offset detected by the abnormality determination unit 20c does not exceed the predetermined value for a predetermined time or more (No in S23), the abnormality determination operation ends. On the other hand, when it is determined that the detected DC offset exceeds the predetermined value for a predetermined time or more (Yes in S23), the abnormality determination unit 20c outputs a notification signal indicating an abnormality of the first reference signal source 51 (S24) . The notification signal is output to the vehicle control unit 55 via the notification signal output terminal 21.

  The vehicle control unit 55 causes the display unit (not shown) installed in the vehicle 50 to display an image indicating an abnormality of the first reference signal source 51 based on such a notification signal, or the vehicle 50. Control is performed to output a sound indicating an abnormality of the first reference signal source 51 to a speaker installed inside.

  Thus, the active noise reduction device 10 can notify the occupant of the vehicle 50 of the abnormality of the first reference signal source 51. The abnormality determination unit 20c may directly output the video signal or the audio signal to the display unit or the speaker as a notification signal.

  When detecting an abnormality in which the DC offset is stuck to the reference voltage (ground), in step S23, the abnormality determination unit 20c determines whether the detected DC offset is lower than a predetermined value for a predetermined time or more. Just do it.

[Modification 1]
In the first embodiment, the abnormality determination unit 20c performs averaging processing of the digital values of the acquired first reference signal, and detects the average of the digital values as the DC offset of the first reference signal. However, the method of detecting the DC offset of the first reference signal is not limited to such a method.

  For example, the detection unit 20 may further include a low pass filter, and detect the DC offset of the input first reference signal by passing the input first reference signal through the low pass filter.

  Accordingly, the detection unit 20 can detect the DC offset without performing the averaging process in the abnormality determination unit 20c. That is, the detection unit 20 can detect the DC offset of the first reference signal while suppressing an increase in the amount of information processing in the abnormality determination unit 20c. In addition, the detection method of the DC offset which performs an equalization process has an effect which can detect the DC offset of a 1st reference signal, suppressing addition of a circuit element.

[Modification 2]
In the first embodiment, the abnormality determination unit 20c detects the DC offset of the first reference signal. However, the abnormality determination unit 20c is an error in place of or in addition to the first reference signal. The DC offset of the signal may be detected. The detection unit 20 performs DC offset of the error signal by performing the signal processing and the like performed on the first reference signal in the first embodiment with respect to the error signal input from the error signal input terminal 13. It can be detected.

[Modification 3]
The abnormality determination unit 20c may perform the abnormality determination using the output signal S of the AD converter 19c of the first input I / F unit 19 (shown by an alternate long and short dash line in FIGS. 2 and 4). For example, when the first reference signal source 51 is a microphone, the abnormality determination unit 20c sets the input level to a certain level or less, with the peak-to-peak of the output signal S in a predetermined period after the output signal S becomes stable. If there is, it is determined that the output signal is abnormal. The predetermined period is, for example, 4 seconds, and the constant level is, for example, about 1% of full scale, but is not particularly limited.

  The specific content of the abnormality can be determined according to the DC offset of the first reference signal. If the DC offset is less than the first threshold and close to 0 V, the abnormality determination unit 20c can determine that the signal line of the first reference signal is grounded or shorted. Further, when the DC offset exceeds the second threshold larger than the first threshold and is close to the pull-up voltage of the first reference signal, the abnormality determination unit 20c determines whether the signal line of the first reference signal is shorted or not It can be determined that there is a break.

  Then, if the DC offset is equal to or greater than the first threshold and equal to or less than the second threshold, and the noise N 0 is generated due to the vehicle 50 traveling, etc., the first reference signal source 51 is broken. It can be determined that In the case where the DC offset is equal to or more than the first threshold and equal to or less than the second threshold, and the noise N0 is not generated, the determination can not be made.

  When the first reference signal source 51 is an acceleration sensor or the like, a short circuit occurs if the DC offset adheres to the power supply voltage, or a disconnection or a ground occurs if the DC offset adheres to the reference voltage (ground) It can be determined that

  The logic of the abnormality determination of the third modification described above is an example, and such logic does not necessarily have to be used.

Second Embodiment
[Configuration of Vehicle Equipped with Noise Reduction Device According to Second Embodiment]
For example, in the case where the first reference signal source 51 is an acceleration sensor, the first reference signal output from the first reference signal source 51 is DC corresponding to the gravity acceleration according to the mounting direction of the first reference signal source 51. An offset appears. Furthermore, DC offset appears in the first reference signal output from the first reference signal source 51 depending on traveling conditions such as acceleration of the vehicle 50, deceleration, curve traveling, and slope traveling. In this case, it may be difficult for the detection unit 20 to determine whether the detected DC offset appears during normal operation of the first reference signal source 51 or appears due to the failure mode.

  Therefore, the detection unit 20 determines the abnormality of the first reference signal source 51 by comparing the DC offset of the first reference signal source 51 with the DC offset of another reference signal source attached to the vehicle 50. It is also good. Hereinafter, the vehicle and the active noise reduction device according to the second embodiment will be described. FIG. 6 is a schematic view of a vehicle provided with the active noise reduction device according to the second embodiment viewed from the top side. In the following second embodiment, description will be made focusing on parts different from the first embodiment, and the description will be omitted for contents overlapping with the first embodiment.

  The vehicle 150 according to the second embodiment includes the active noise reduction device 110 according to the second embodiment, a first reference signal source 151, a second reference signal source 251, a cancellation sound source 52, and an error signal source 53. A vehicle body 54 and a vehicle control unit 55 are provided. That is, the main difference between the vehicle 150 and the vehicle 50 is that the second reference signal source 251 is provided in addition to the first reference signal source 151.

  The second reference signal source 251 is a transducer that outputs a second reference signal that has a correlation with noise in the space 57 of the vehicle interior of the vehicle 50. Specifically, the second reference signal source 251 is an acceleration sensor.

  Similar to the first reference signal source 51, the first reference signal source 151 is attached to a sub-frame near the right front wheel (or a tire house of the right front wheel). On the other hand, the second reference signal source 251 is attached to, for example, a sub-frame near the left front wheel (or a tire house of the left front wheel). The mounting position of the first reference signal source 51 is not particularly limited.

[Configuration of Active Noise Reduction Device According to Second Embodiment]
Next, the functional configuration of the active noise reduction device 110 will be described. FIG. 7 is a block diagram showing a functional configuration of the active noise reduction device 110. As shown in FIG.

  As shown in FIG. 7, the active noise reduction device 110 includes a first reference signal input terminal 111, a second reference signal input terminal 211, a cancel signal output terminal 112, an error signal input terminal 113, and a first signal. Processing unit 114, first input I / F unit 119, second signal processing unit 214, second input I / F unit 219, storage unit 118, detection unit 120, notification signal output terminal 121, And an adding unit 122. The first signal processing unit 114 includes an adaptive filter unit 115, a simulated acoustic transfer characteristic filter unit 116, and a filter coefficient updating unit 117. The second signal processing unit 214 includes an adaptive filter unit 215, a simulated acoustic transfer characteristic filter unit 216, and a filter coefficient updating unit 217.

  The first signal processing unit 114 uses the first reference signal input to the first reference signal input terminal 111 to generate a cancellation signal used for the output of the cancellation sound for reducing the noise N0. The second signal processing unit 214 uses the second reference signal input to the second reference signal input terminal 211 to generate a cancellation signal used for outputting a cancellation sound for reducing the noise N0. The functions and operations of the first signal processing unit 114 and the second signal processing unit 214 are the same as those of the first signal processing unit 14.

  The second reference signal input terminal 211 is an example of a second input unit, and receives a second reference signal output by a second reference signal source 251 attached to the vehicle 150. The second reference signal input terminal 211 is a terminal formed of metal or the like.

  The cancel signal output from the first signal processing unit 114 and the cancel signal output from the second signal processing unit 214 are added by the adding unit 122 and then output to the cancel signal output terminal 112.

  The addition unit 122 adds the cancel signal output from the first signal processing unit 114 and the cancel signal output from the second signal processing unit 214, and outputs the cancel signal after addition to the cancel signal output terminal 112. . The adding unit 122 is realized by, for example, a processor such as a DSP, but may be realized by an adding circuit using a microcomputer or an operational amplifier.

  The detection unit 120 further detects the DC offset of the second reference signal input to the second reference signal input terminal 211 in addition to the DC offset of the first reference signal input to the first reference signal input terminal 111. FIG. 8 is a diagram showing a detailed configuration of the detection unit 120. As shown in FIG. In FIG. 8, detailed configurations of the first input I / F unit 119 and the second input I / F unit 219 are also illustrated.

  The first input I / F unit 119 and the second input I / F unit 219 have the same configuration as the first input I / F unit 19. Specifically, the first input I / F unit 119 includes a capacitive element 119a, a band pass filter 119b, and an AD converter 119c. Specifically, the second input I / F unit 219 includes a capacitive element 219a, a band pass filter 219b, and an AD converter 219c.

  The detection unit 120 includes a voltage dividing circuit 120 a and an AD converter 120 b as components for detecting a DC offset of the first reference signal, and as a component for detecting a DC offset of the second reference signal. , A voltage dividing circuit 220a, and an AD converter 220b.

  The abnormality determination unit 120 c monitors the digital value of the digitized first reference signal and the digital value of the digitized second reference signal to determine an abnormality of the first reference signal source 51. The abnormality determination unit 120c is specifically realized by a microcomputer, but may be realized by a processor or a dedicated circuit. The abnormality determination unit 120c may be realized by a combination of two or more of a microcomputer, a processor, and a dedicated circuit. When the abnormality determination unit 120 c operates by executing a control program, such a control program is stored in the storage unit 118. The storage unit 118 also stores determination conditions used by the abnormality determination unit 120c to determine the presence or absence of an abnormality.

[Abnormality determination operation according to the second embodiment]
Hereinafter, the abnormality determination operation of the abnormality determination unit 120c will be described with reference to a flowchart. FIG. 9 is a flowchart of the abnormality determination operation of the abnormality determination unit 120c.

  First, the abnormality determination unit 120c acquires a digitized first reference signal from the AD converter 120b (S31). Next, the abnormality determination unit 120c detects a DC offset of the acquired first reference signal (S32). The abnormality determination unit 120 c performs, for example, an averaging process of digital values of the acquired first reference signal, and detects an average of the digital values as a first DC offset of the first reference signal.

  Similarly, the abnormality determination unit 120c acquires a digitized second reference signal from the AD converter 220b (S33), and detects a second DC offset of the acquired second reference signal (S34). The abnormality determination unit 120 c performs, for example, an averaging process of digital values of the acquired second reference signal, and detects an average of the digital values as a second DC offset of the second reference signal.

  Next, the abnormality determination unit 120c compares the detected first DC offset and the detected second DC offset (S35). For example, when detecting an abnormality in which the DC offset is stuck to the positive power supply voltage, the abnormality determination unit 120c determines whether the first DC offset is greater than or equal to a predetermined value and greater than the second DC offset (S36) .

  When it is determined that the first DC offset is not larger than the predetermined value and not larger than the second DC offset (No in S36), the abnormality determination unit 120c determines that the second DC offset is larger than the predetermined value and larger than the first DC offset. It is determined whether or not (S37). When it is determined that the second DC offset is not larger than the predetermined value and not larger than the first DC offset (No in S37), the abnormality determination operation is ended.

  On the other hand, when it is determined in step S35 that the first DC offset is greater than or equal to the predetermined value and larger than the second DC offset (No in S36), the second DC offset is stuck to the positive power supply voltage, and the first reference signal source It is considered that 151 is abnormal. Similarly, in step S36, when it is determined that the second DC offset is greater than or equal to the predetermined value and larger than the first DC offset (No in S37), the second DC offset adheres to the positive power supply voltage, and the second reference signal It is considered that the source 251 is abnormal.

  Therefore, in such a case, the abnormality determination unit 120c outputs a notification signal indicating an abnormality of the first reference signal source 151 or the second reference signal source 251 (S38). The notification signal is output to the vehicle control unit 55 via the notification signal output terminal 121.

  As described above, in the active noise reduction device 110, the detection unit 120 further detects the DC offset of the input second reference signal, and the first DC offset of the first reference signal and the second of the second reference signal. A notification signal indicating abnormality of the first reference signal source 151 or the second reference signal source 251 is output based on the comparison result of the DC offset. Thereby, even when the first reference signal source 151 and the second reference signal source 251 are acceleration sensors, abnormality determination based on DC offset can be performed with high accuracy.

  The first reference signal source 151 and the second reference signal source 251 are attached to the vehicle 50, for example, such that the axial directions serving as the reference of measurement of acceleration are aligned. Thereby, the comparison of the first DC offset and the second DC offset can be appropriately performed. When the axial directions of the first reference signal source 151 and the second reference signal source 251 are different, it is preferable that signal processing such as tensor conversion be performed, and then components in the same direction be compared.

(Effect, etc.)
As described above, the active noise reduction device 10 is an active noise reduction device that reduces the noise N0 in the space in the vehicle 50. The active noise reduction device 10 receives the first reference signal input terminal 11 to which the first reference signal having a correlation with the noise N0 output by the first reference signal source 51 attached to the vehicle 50 is input. A first signal processing unit 14 that generates a cancellation signal used for outputting the cancellation sound N1 for reducing the noise N0 using the first reference signal, and a detection that detects a DC offset of the input first reference signal And a unit 20. The first reference signal input terminal 11 is an example of a first input unit.

  Thereby, the active noise reduction device 10 can detect an abnormality of the first reference signal source 51 when the first reference signal source 51 has a failure mode in which the DC offset fluctuates.

  Also, for example, when the detected DC offset exceeds the predetermined value for the predetermined time or more, or when the detected DC offset is less than the predetermined value for the predetermined time, the detection unit 20 may perform the first reference signal source 51 Output a signal indicating an abnormality of

  Thereby, the first reference signal source 51 has a failure mode in which the DC offset is stuck to a positive voltage, or the first reference signal source 51 has a failure mode in which the DC offset is stuck to a reference voltage (ground). In addition, the active noise reduction device 10 can detect and notify of an abnormality of the first reference signal source 51.

  Also, for example, the active noise reduction device 110 further includes a second reference signal input terminal to which a second reference signal correlated with the noise N0, which is output by the second reference signal source 251 attached to the vehicle 50, is input. And 211. The second reference signal input terminal is an example of a second input unit. The detection unit 120 further detects the DC offset of the input second reference signal, and based on the comparison result of the DC offset of the first reference signal and the DC offset of the second reference signal, the first reference signal source 151 or the A signal indicating abnormality of the second reference signal source 251 is output.

  Thus, the active noise reduction device 110 accurately determines the abnormality based on the DC offset even when the first reference signal source 151 and the second reference signal source 251 are acceleration sensors and a DC offset appears in the absence of an abnormality. Can be done.

  Also, for example, the active noise reduction device 10 may further include a capacitive element 19a that cuts a DC offset of the input first reference signal. The first signal processing unit 14 generates a cancel signal using the input first reference signal and the first reference signal whose DC offset has been cut by the capacitive element 19 a. The detection unit 20 detects the DC offset of the first reference signal which is the input first reference signal and before the DC component is cut by the capacitive element 19a.

  As a result, since the DC offset is cut by the capacitive element 19a, the active noise reduction device 10 realizes the detection of the DC offset by the detection unit 20 even when the detection of the DC offset is difficult by the first signal processing unit 14. Can.

  Also, for example, the active noise reduction device 10 may further include a band pass filter 19 b that cuts a DC offset of the input first reference signal. The first signal processing unit 14 generates a cancel signal using the input first reference signal and the first reference signal whose DC offset has been cut by the band pass filter 19 b. The detection unit 20 detects the DC offset of the first reference signal that is the input first reference signal before the DC component is cut by the band pass filter 19 b.

  Thereby, since the DC offset is cut by the band pass filter 19b, even when the detection of the DC offset is difficult by the first signal processing unit 14, the active noise reduction device 10 realizes the detection of the DC offset by the detection unit 20. be able to.

  Also, for example, the detection unit 20 detects the DC offset of the input first reference signal by performing averaging processing of the input first reference signal.

  Thereby, the detection unit 20 can detect the DC offset of the first reference signal by suppressing the addition of the circuit element.

  Also, for example, the detection unit 20 further includes a low pass filter, and detects the DC offset of the input first reference signal by passing the input first reference signal through the low pass filter.

  Thus, the detection unit 20 can detect the DC offset of the first reference signal while suppressing an increase in the amount of information processing in the abnormality determination unit 20c.

  Also, for example, the first reference signal source 51 is an acceleration sensor.

  Thereby, the detection part 20 can detect DC offset contained in the 1st reference signal which an acceleration sensor outputs.

  Also, for example, the first reference signal source 51 is a microphone.

  Thereby, the detection unit 20 can detect the DC offset included in the first reference signal output by the microphone.

  Also, the detection unit 20 may detect the DC offset of the error signal. In this case, the active noise reduction device 10 outputs a first reference signal input terminal 11 to which a first reference signal having a correlation with the noise N0, which is output by a first reference signal source attached to the vehicle 50, and A first signal processing unit 14 for generating a cancellation signal used for outputting the cancellation sound N1 for reducing the noise N0 using the first reference signal, and residual sound due to interference between the cancellation sound N1 and the noise N0 And a detection unit 20 for detecting a DC offset of the input error signal. The first reference signal input terminal 11 is an example of a first input unit, and the error signal input terminal 13 is an example of an error signal input unit.

  The vehicle 50 further includes an active noise reduction device 10 and a first reference signal source 51. Vehicle 50 may include an active noise reduction device 110.

  Such a vehicle 50 can detect an abnormality of the first reference signal source 51.

  Further, the abnormality determination method executed by the active noise reduction device 10 for reducing noise in the space in the vehicle 50 is a first correlation signal output from the first reference signal source 51 attached to the vehicle 50 and noise N0 The reference signal is acquired, and the acquired first reference signal is used to generate a cancellation signal used for the output of the cancellation sound N1 for reducing the noise N0, and to detect the DC offset of the acquired first reference signal And outputs a signal indicating an abnormality of the first reference signal source 51 based on the detection result of the DC offset of the first reference signal.

  Thereby, the abnormality determination method can detect and notify the abnormality of the first reference signal source 51 when the first reference signal source 51 has a failure mode in which the DC offset fluctuates.

(Other embodiments)
The first and second embodiments have been described above, but the present invention is not limited to the first and second embodiments.

  For example, in the above embodiment, the reference signal (first reference signal or second reference signal) is the output signal of the acceleration sensor or the microphone, but the reference signal is calculated based on the number of rotations of the vehicle engine It may be a sine wave.

  Also, for example, the arrangement of the reference signal source and the cancellation sound source described in the above embodiment is an example. FIG. 10 is a view showing an arrangement example of the reference signal source and the cancellation sound source.

  As in a vehicle 250 shown in FIG. 10, in a vehicle provided with an active noise reduction device, a configuration using four reference signal sources 51a to 51d and four cancellation sound sources 52a to 52d can be considered. The reference signal source 51a is attached to the sub-frame near the right front wheel, the reference signal source 51b is attached to the sub-frame near the left front wheel, and the reference signal source 51c is attached to the sub-frame near the right rear wheel The signal source 51d is attached to a sub-frame near the rear left wheel. The cancellation sound source 52a is attached to the right front door, the cancellation sound source 52b is attached to the left front door, the cancellation sound source 52c is attached to the right rear door, and the cancellation sound source 52d is attached to the left rear door.

  An active noise reduction device provided in such a vehicle can obtain four reference signals. In this case, the detection unit detects the DC offset of each of the four reference signals. The detection unit may determine that the reference signal source having a DC offset larger by a predetermined value or more than the average value is abnormal, based on the average value of the four detected DC offsets.

  The configuration of the active noise reduction device according to the first and second embodiments is an example. For example, the active noise reduction device may include components such as a D / A converter, a filter, a power amplifier, or an A / D converter.

  Moreover, the process which the active noise reduction apparatus which concerns on the said Embodiment 1 and 2 performs is an example. For example, part of the digital signal processing described in the above embodiments may be realized by analog signal processing.

  Also, for example, in the above-described first and second embodiments, another processing unit may execute the processing executed by a specific processing unit. In addition, the order of a plurality of processes may be changed, or a plurality of processes may be executed in parallel.

  In the first and second embodiments, each component may be configured by dedicated hardware or implemented by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded in a recording medium such as a hard disk or a semiconductor memory.

  Also, each component may be a circuit (or integrated circuit). These circuits may constitute one circuit as a whole or may be separate circuits. Each of these circuits may be a general-purpose circuit or a dedicated circuit.

  Also, the general or specific aspects of the present invention may be realized by a non-transitory recording medium such as a system, an apparatus, a method, an integrated circuit, a computer program or a computer readable CD-ROM. Also, the present invention may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program and a non-transitory computer readable recording medium.

  For example, the present invention may be implemented as an abnormality determination method executed by an active noise reduction device (computer or DSP), or as a program for causing a computer or DSP to execute the above abnormality determination method. In addition, the present invention may be realized as a vehicle or a noise reduction system including the active noise reduction device according to the above-described embodiment, the first reference signal source, the cancellation sound source, and the error signal source.

  In addition, the embodiments can be realized by various combinations that each person skilled in the art can think of for each embodiment, or by combining components and functions in each embodiment without departing from the scope of the present invention. The embodiments of the present invention are also included in the present invention.

  The active noise reduction device of the present invention is useful, for example, as a device capable of reducing noise in a vehicle compartment and detecting an abnormality in a reference signal source.

10, 110 Active noise reduction device 11, 111 First reference signal input terminal 12, 112 Cancel signal output terminal 13, 113 Error signal input terminal 14, 114 First signal processing unit 15, 115, 215 Adaptive filter unit 16, 116, 216 simulated acoustic transfer characteristic filter unit 17, 117, 217 filter coefficient update unit 18, 118 storage unit 19, 119 first input I / F unit 19a, 119a, 219a capacitive element 19b, 119b, 219b band pass filter 19c, 20b, 119c, 120b, 219c, 220b AD converter 20, 120 detection unit 20a, 120a, 220a voltage dividing circuit 20c, 120c abnormality determination unit 21, 121 notification signal output terminal 50, 150, 250 vehicle 51, 151 first reference signal source 51a , 51b, 51c, 5 d Reference signal source 52, 52a, 52b, 52c, 52d Cancel sound source 53 Error signal source 54 Vehicle main body 55 Vehicle control unit 57 Space 122 Addition unit 211 Second reference signal input terminal 214 Second signal processing unit 219 Second input I / F part 251 2nd reference signal source N0 noise N1 cancellation sound

Claims (12)

An active noise reduction device for reducing noise in a space in a vehicle, comprising:
A first input output from a first reference signal source attached to the vehicle, to which a first reference signal correlated with the noise is input;
A signal processing unit that generates a cancellation signal used for outputting a cancellation sound for reducing the noise using the input first reference signal;
And a detection unit that detects a DC (Direct Current) offset of the input first reference signal. The detection unit indicates an abnormality of the first reference signal source when the detected DC offset exceeds a predetermined value for a predetermined time or more, or when the detected DC offset falls below a predetermined value for a predetermined time or more. The active noise reduction device according to claim 1, which outputs a signal. The active noise reduction apparatus further includes a second input unit to which a second reference signal correlated with the noise, which is output by a second reference signal source attached to the vehicle, is input.
The detection unit further detects a DC offset of the input second reference signal, and based on a comparison result of the DC offset of the first reference signal and the DC offset of the second reference signal, the first reference signal The active noise reduction device according to claim 1, which outputs a signal indicating an abnormality of a source or the second reference signal source. And a capacitive element for cutting a DC offset of the input first reference signal,
The signal processing unit generates the cancel signal using the input first reference signal, and the first reference signal whose DC offset has been cut by the capacitive element.
The said detection part is a said 1st reference signal input, Comprising: The DC offset of the said 1st reference signal before DC component is cut by the said capacitive element is detected. Active noise reduction device according to claim 1. And a band pass filter for cutting a DC offset of the input first reference signal,
The signal processing unit generates the cancel signal using the first reference signal that has been input and whose DC offset has been cut by the band pass filter.
The detection unit detects a DC offset of the first reference signal before the DC component is cut by the band pass filter, which is the input first reference signal. An active noise reduction device according to claim 1. The active state according to any one of claims 1 to 5, wherein the detection unit detects a DC offset of the input first reference signal by averaging the input first reference signal. Noise reduction device. The detection unit further includes a low pass filter, and detects a DC offset of the input first reference signal by passing the input first reference signal through the low pass filter. Active noise reduction device according to any one of the preceding claims. The active noise reduction device according to any one of claims 1 to 7, wherein the first reference signal source is an acceleration sensor. The active noise reduction device according to any one of claims 1 to 7, wherein the first reference signal source is a microphone. An active noise reduction device for reducing noise in a space in a vehicle, comprising:
A first input output from a first reference signal source attached to the vehicle, to which a first reference signal correlated with the noise is input;
A signal processing unit that generates a cancellation signal used for outputting a cancellation sound for reducing the noise using the input first reference signal;
An error signal input unit to which an error signal corresponding to residual sound due to interference between the cancellation sound and the noise is input;
An active noise reduction device comprising: a detection unit that detects a DC offset of the input error signal. An active noise reduction device according to any one of claims 1 to 10,
And a vehicle comprising the first reference signal source. An abnormality determination method executed by an active noise reduction device for reducing noise in a space in a vehicle, comprising:
Acquiring a first reference signal correlated with the noise, output by a first reference signal source mounted on the vehicle;
Using the acquired first reference signal to generate a cancellation signal used for outputting a cancellation sound for reducing the noise;
Detecting a DC offset of the acquired first reference signal;
And outputting a signal indicating an abnormality of the first reference signal source based on the detection result of the DC offset of the first reference signal.

Images