JP5040163B2 - Noise reduction apparatus and method - Google Patents

Description

  The present invention relates to a noise reduction apparatus and method for reducing noise in a vehicle interior by generating vibration or sound.

  Conventionally, as a technique for performing feedback control for the purpose of reducing vehicle interior noise, the following Patent Document 1 is known. In this Patent Document 1, an actual noise is detected using a microphone, and an operation of reducing road noise in a low frequency band of 100 Hz or less among the noise is performed. This technology assumes that road noise in the low frequency band is generated due to the acoustic mode of the vehicle interior sound field, and then installs a microphone on the belly of the acoustic mode to perform the acoustic mode by feedback control. Is a method of canceling out.

  In addition, as described in Patent Document 2 below, a technique is also known in which a microphone is installed in a vehicle interior and a noise signal obtained from the microphone is canceled using a feedback controller.

Furthermore, as described in Patent Document 3 below, a technique for performing feedforward control for the purpose of reducing vehicle interior noise is known, and Patent Document 3 includes a seat headrest portion. An error signal is detected using a microphone, and a reference signal is detected from an acceleration sensor at the door hinge, thereby reducing vehicle interior noise using an adaptive filter.
JP 2000-322066 A JP 2000-32206 A (FIG. 10 etc.) Japanese Patent Laid-Open No. 8-2922771

  However, in the above-described technique, since the acoustic mode is detected and controlled with respect to the acoustic mode, it is desirable to obtain a control effect in the entire space. However, in the low frequency band where the acoustic mode can be accurately identified. It can be reduced only with respect to noise. In practice, the conventional example has a problem that only so-called drumming noise of 40 Hz and 80 Hz is handled as a control target.

  In addition, the above-described technologies of Patent Documents 1 and 2 that feed back a noise signal obtained from a microphone and the technology of Patent Document 3 try to realize an effect of reducing noise according to the installation position of the microphone. Since the noise was reduced even in a space that was not provided, the noise could not be effectively reduced particularly at the occupant position.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and an object thereof is to provide a noise reduction device and method that can effectively reduce noise in a space where a passenger is present depending on the presence or absence of the passenger. And

A noise reduction device according to the present invention includes a vibration detection unit that detects vibrations of a vehicle body, a noise reduction unit that is provided in each seat of the vehicle and that generates vibrations or sounds to reduce noise in the vehicle interior, and a vibration detection unit. Control command value calculating means for calculating a control command value for controlling vibration or sound generated by the noise reduction means in accordance with the detected vibration, and occupant detection means for detecting the presence or absence of an occupant in the passenger compartment, and In order to solve the above problem, the control command value calculation means adjusts the control command value so that the noise reduction control effect is obtained in the space where the occupant detected by the occupant detection means is present , and the noise reduction means In addition to controlling the vibration or sound to be generated, and when there is a seat determined by the occupant detection means that there is no occupant, the noise reduction means corresponding to this seat is used to In the space that is determined, so as to enlarge the area noise reduction control effect is obtained, adjusting the control command value.

In order to solve the above-described problem, the noise reduction method according to the present invention detects the vibration of the vehicle body and detects the presence or absence of an occupant in the vehicle cabin when reducing the noise in the vehicle cabin by generating vibration or sound. Adjusting a control command value supplied to a noise reduction means that is provided in each seat of the vehicle and generates vibration or sound so that a noise reduction control effect can be obtained in a space where a detected occupant exists; and Supplying the adjusted control command value to the noise reduction means, and the step of adjusting the control command value corresponds to the seat when it is determined that there is no occupant. Using the noise reduction means, the control command value is adjusted so as to expand the area where the noise reduction control effect can be obtained in the space where it is determined that there are passengers.

  According to the present invention, the control command value is adjusted so that the noise reduction control effect is obtained in the space where the occupant is present, and the vibration or sound generated by the noise reduction means is controlled. Noise in a space where passengers are present can be effectively reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
For example, as shown in FIGS. 1 and 2, the present invention provides a noise reduction device that detects the presence or absence of an occupant in a control space PA, PB, PC, or PD in a vehicle interior and reduces noise according to the presence or absence of the occupant. Applied.

  For example, as shown in FIG. 2, the noise reduction device according to the first embodiment has a capacity of four people, and a driver's seat 6B, a passenger seat 6A, and rear seats 6C and 6D (hereinafter collectively referred to as “seat 6A, 6B, 6C, 6D ") is provided and the noise in the control spaces PA, PB, PC, PD when the occupants get on the seats 6A, 6B, 6C, 6D will be described. By arranging the occupant detection sensors in all the seats and defining the respective spaces, it is possible to achieve the same noise reduction control effect for vehicles with different capacity.

  This noise reduction apparatus includes an acceleration sensor 4 that is a vibration detection unit that detects vibrations of a vehicle body, and piezoelectric actuators 5A, 5B that are noise reduction units that generate vibrations that reduce noise in the passenger compartment. Control vibrations generated by the piezoelectric actuators 5A, 5B, 5C, and 5D in accordance with the vibrations detected by the acceleration sensor 4 and 5C and 5D (hereinafter simply referred to as “piezoactuator 5” when collectively referred to). A controller unit 8 which is a control command value calculation means for calculating a control command value to be detected, and an occupant detection means for detecting the presence or absence of an occupant in each seat in the vehicle interior, provided in each seat 6A, 6B, 6C, 6D of the vehicle. Occupant detection sensors 7A, 7B, 7C, and 7D. Such a noise reduction device is controlled by the controller unit 8 so that the noise reduction control effect is obtained in the space where the occupant is present according to the presence or absence of the occupant detected by the occupant detection sensors 7A, 7B, 7C and 7D. And the vibration generated by the piezo actuators 5A, 5B, 5C, 5D is controlled. In this embodiment, the noise reduction means is described as generating vibration, but noise may be reduced by directly generating sound.

  In general, the cause of vehicle interior noise entering from the outside of the vehicle interior is that the engine noise caused by the vibration of the engine 3 and the influence of road surface unevenness entering the floor panel 1 from the tire 2 when traveling are typical. There are road noise noise caused by it, wind noise generated by air flow during driving, and so on.

  The present invention mainly aims to reduce road noise. FIG. 1 shows main propagation paths of vehicle body vibration and road noise caused by road surface unevenness. The vibration that is the main component of road noise that enters the vehicle body from the tire 2 first enters a highly rigid beam-like member called a member from the axle and suspension attachment points. Thereafter, vibration propagates to a plate-like member called floor panel 1 surrounded by the members and having relatively low rigidity, and this floor panel 1 vibrates. Further, in the control spaces PA, PB, PC, PD in the vicinity of the head in a state where an occupant is seated in order to cause an air vibration in the passenger compartment due to the membrane vibration of the floor panel 1 and cause a resonance phenomenon in the passenger compartment. Road noise can be heard. Although noise is generated when the roof panel and the window glass vibrate in addition to the floor panel 1, most of the road noise that mainly enters from the suspension mounting portion is caused by the vibration of the floor panel 1. know.

  For this purpose, the noise reduction apparatus arranges the acceleration sensor 4 on the floor panel 1 to estimate noise in the control spaces PA, PB, PC, PD at the position of the occupant head, and to detect the piezoelectric actuators 5A, 5B, 5C, A control command signal for 5D is generated, and a control sound due to vibrations of the piezoelectric actuators 5A, 5B, 5C, 5D is input into the passenger compartment. Therefore, the road noise caused by the floor panel 1 is mainly handled as a control target. In addition, since all the noises generated from the floor panel 1 are included as control targets, a part of the noise of the engine 3 and wind noise generated by the air flowing through the bottom of the vehicle body can be handled in the same manner. In addition, the scope of the effect of the present invention is not limited to the category of noise reduction due to vibration of the floor panel 1, but also for vehicle interior noise generation sources generated by the same mechanism such as a dash panel, a windshield, and a roof panel. If the acceleration sensor 4 and the piezo actuator 5 are provided in the part, similarly, noise generated by vibration of the part can be reduced.

  As shown in FIG. 2, the controller unit 8 inputs the vibration of the floor panel 1 from the acceleration sensor 4 as an acceleration signal, and transmits an occupant detection signal indicating the presence or absence of the occupant's seats 6A, 6B, 6C, 6D. 7A, 7B, 7C, and 7D are input, and a control command value for reducing noise in the control spaces PA, PB, PC, and PD is obtained by performing arithmetic processing described later, and the piezo actuators 5A, 5B, 5C, and 5D are obtained. Drive to give vibration to the floor panel 1.

  The occupant detection sensors 7A, 7B, 7C, and 7D include, for example, an acceleration sensor and a pressure sensor arranged on the seat bottom surface, and supply the detected value to the controller unit 8 as an occupant detection signal. The occupant detection signal is amplified by the amplifiers 12 and 14 in the controller unit 8 and then supplied to the controller 11 which is an arithmetic circuit for calculating a control command value of a CPU (Central Processing Unit) or the like. The acceleration signal detected by the acceleration sensor 4 is amplified by the amplifier 13 in the controller unit 8 and then supplied to the controller 11.

  The controller 11 uses the acceleration signal from the acceleration sensor 4, the control command signal to the piezo actuators 5A, 5B, 5C, and 5D, and the occupant detection signals from the occupant detection sensors 7A, 7B, 7C, and 7D. A control command signal is calculated so that noise in the control spaces PA, PB, PC, and PD on 6B, 6C, and 6D is reduced. The controller 11 detects the presence or absence of an occupant in the seats 6A, 6B, 6C, and 6D from the occupant detection signals from the occupant detection sensors 7A, 7B, 7C, and 7D, and controls the control spaces PA, PB, The noise in the PC and PD is estimated from the acceleration signal detected by the acceleration sensor 4, and a control command value that reduces the noise in the control spaces PA, PB, PC, and PD where the passenger is present is calculated. This control command value is supplied to the piezo actuators 5A, 5B, 5C, and 5D of the seats 6A, 6B, 6C, and 6D where the passenger is present via the amplifier 15.

  As shown in FIG. 3, the controller 11 includes a noise estimation device 21, an input switch 22, calculators 23 </ b> A,... A switch 24 and a switching trigger generator 25 are included. The controller 11 sets the correspondence between the control spaces PA, PB, PC, PD and the parameters for calculating the control command values in the calculators 23A,..., 23H, and seats 6A, 6B, The switching state of the input switch 22 and the output switch 24 is switched according to the patterns 6C and 6D, and the computing unit 23 that matches the pattern is selected. Each calculator 23 has different calculation parameters for calculating the control command signal, and calculates the control command signal with a calculation parameter that enhances the silencing control effect in the control spaces PA, PB, PC, and PD where the occupants are present.

The pattern of the seats 6A, 6B, 6C, 6D in which the passengers are present is the number and arrangement of passengers in the passenger compartment, for example, the state in which the passengers are present only in the driver seat 6B, the driver seat 6B, the passenger seat 6A, and the rear seat 6C. State where there are passengers. For example, in the case of a vehicle with four seats, the switching trigger generator 25 prepares variables s ₁ , s ₂ , s ₃ corresponding to the respective seats 6A, 6C, 6D other than the driver's seat 6B, and there are passengers. The occupant arrangement is determined by setting the determined seat variable to 1 and setting the seat variable determined to have no occupant to 0. Since driver's seat 6B is always on board, there is no need to set a variable. Then, by supplying the variables s ₁ , s ₂ , and s ₃ to the input switch 22 and the output switch 24, the calculator 23 that calculates the control command signal is switched.

  The calculator 23 calculates a control command signal that reduces the noise estimated by the noise estimation device 21. In this calculator 23, different calculation parameters are set according to the number of passengers and the passenger arrangement.

For example, there are 2 ³ = 8 switching patterns for 4 persons, and there are 8 computing units 23 corresponding to the 8 patterns, and the computing parameters of each computing unit 23 are designed corresponding to each pattern. ing. For example, the calculator 23A is designed to calculate a control command signal that can achieve a silencing control effect only in the control space PB in the driver's seat 6B, and the calculator 23B includes the control spaces PA, The PB is designed to calculate a control command signal that provides a silencing control effect.

  The noise estimation device 21 estimates noise (sound pressure) in the control spaces PA, PB, PC, PD using the acceleration signal and the control command value. The control spaces PA, PB, PC, and PD are in the vicinity of the occupant head position when the occupant is seated on the seats 6A, 6B, 6C, and 6D, and the noise estimation device 21 estimates noise at the occupant head position. As shown in FIG. 4, the noise estimation device 21 performs a control command for calculating a vibration transfer function at the position of the acceleration sensor 4 from the control command signal → the position of the vibration calculation unit 31, the adder 32, and the acceleration sensor 4. The vibration for calculating the noise transfer function in the control spaces PA, PB, PC, PD from the vibration of the sound → the sound pressure calculation unit 33, the transfer function of the noise in the control spaces PA, PB, PC, PD from the control command signal A control command for performing calculation → a sound pressure calculation unit 34 and an adder 35 are provided.

The noise estimation device 21 inputs an acceleration signal and a control command signal as input signals. If the necessary number of acceleration sensors 4 are arranged at appropriate positions and the coherence between the noise in the vehicle interior and the acceleration signal is close to 1, it can be determined that the noise can be estimated from the acceleration signal. Specifically, the coherence C _xy ² is as shown in Equation 1 below:

It is described by a function like Here, x is an output vector of the acceleration sensor 4, y is a sound pressure in the control space PA, PB, PC, PD, _Sxy is a cross spectral density between x and y, and _Sxx is a cross spectral density of x. , S _yy represents the power spectral density. From Equation 1, the acceleration sensor 4 is arranged so that the coherence C _xy ² is a predetermined reference value (for example, 0.9) or more. As described above, the noise estimation device 21 can obtain the estimated noise in the control spaces PA, PB, PC, PD from the acceleration signal and the control command signal.

For example, the transfer function from the control command signal used in the control command → sound pressure calculation unit 34 to the sound pressure in the control spaces PA, PB, PC, PD is first set to the floor panel 1 with the piezoelectric actuators 5A, 5B, 5C, 5D. And a microphone (not shown) are installed in the control spaces PA, PB, PC, and PD, and predetermined M-sequence signals that generate vibrations as samples are input to the piezoelectric actuators 5A, 5B, 5C, and 5D. The M-sequence signal and the microphone detection signal are measured. Then, for example, by using “System Identification Toolbox” operating on the control system design CAD “MATLAB” for the obtained M-sequence signal and microphone detection signal, for example, the discrete time states of the following equations 2 and 3 It is a spatial model

Is modeled in the form Here, x (t) in Equation 2 is a state variable of the model, u (t) is an M-sequence signal to the piezoelectric actuators 5A, 5B, 5C, and 5D, and y (t) in Equation 3 is control space PA, PB, The sound pressures at the PC and PD are represented, the matrices A, B, C, and D are model parameter matrices, respectively, and n is the sample time.

  Alternatively, system identification by mode analysis may be performed using “Structural Dynamic Toolbox” manufactured by SDTOOLS, which operates on the control system design CAD “MATLAB”. In this case, a non-parametric transfer function in the frequency domain obtained by performing Fourier transform on the input / output signal is calculated in advance, and the transfer function used in the control command → sound pressure calculation unit 34 by using the above-described MATLAB toolbox. Can be obtained. The frequency characteristic of the transfer function actually obtained by the above method is as shown in FIG.

  The transfer function used in the vibration → sound pressure calculation unit 33 is a road surface on which an acceleration sensor 4 is first installed on the floor panel 1 and a microphone is installed in the control spaces PA, PB, PC, PD, and road noise is likely to occur. Can be obtained as a discrete-time state space model by using “System Identification Toolbox” operating on the control system design CAD “MATLAB” for the obtained acceleration signal and microphone signal.

Next, a process using the normalized convention decomposition method as a calculation parameter design method in the calculator 23 will be described using the block diagram shown in FIG. Here, the signal B is input to the computing unit 41 to be designed, and control command signals to the piezoelectric actuators 5A, 5B, 5C, 5D are output. The control command signal is input to the transfer function model 42. The transfer function model 42 is a model indicating “transfer characteristics from the control command signal of the piezo actuators 5A, 5B, 5C, and 5D to the noise in the control spaces PA, PB, PC, and PD” modeled by the above-described procedure. . The signal output from the transfer function model 42 and the signal A (disturbance) are overlapped to form a signal B (vehicle interior noise). The transfer characteristic from the signal A to the signal B is a function called “sensitivity function”. By designing the computing unit 41 so that the transfer characteristic from the signal A to the signal B becomes small in a desired frequency band, Appropriate calculation parameters can be set. Examples of such a design method include PID control, H2 control, H∞ control, and the like. Also,
Hosoe, Araki, “Control System Design, H∞ Control and its Applications”, Asakura Shoten, 1994
Suda, “PID Control”, Asakura Shoten, 1992
By using the design method described in the above, it is possible to design an I-order dynamic controller Ki, i = 1,.

In Equation 4, u (n) represents a control command value at time n, and y (i) represents a signal A representing estimated noise.

  Further, in the normalization protocol decomposition method described above, by specifying a weighting function that is a calculation parameter of the calculator 23, a noise frequency band that provides a noise reduction control effect and a noise reduction that indicates the degree of the noise reduction control effect. The width can be changed. For example, as shown in FIG. 7, a frequency characteristic of a weighting function having a characteristic that a certain frequency band has a large gain and the other frequencies have a small gain can be obtained. By designing the computing unit 23 using this weight function, it is possible to enhance the noise reduction control effect with respect to the noise in the frequency band to which a large gain is applied, and to reduce the noise with respect to the noise in the frequency band with a low gain. The computing unit 23 that reduces the control effect can be designed.

  Further, like a weight function as shown in FIG. 8, a frequency band having a high gain may be widened, and instead, the gain may be made smaller than in the case of FIG. By designing the computing unit 23 so as to have such a weight function, it is possible to design the computing unit 23 that computes a control command signal that reduces noise in a wide frequency band compared to the case of FIG.

  By designing the weight function in this way, the calculation parameters of the calculator 23 can be set to change the control effect of the noise reduction device. For example, when there are no passengers in the control spaces PC and PD of the rear seats 6C and 6D Furthermore, the noise reduction effect in the control spaces PA and PB can be increased by increasing the weighting function in the control spaces PA and PB of the passenger seat 6A and the driver seat 6B as shown in FIG. Further, if the weight function is used to widen the frequency bandwidth as shown in FIG. 8, it is possible to reduce noise over a wide frequency band in the control spaces PA and PB. Furthermore, noise in the front passenger seat 6A and the driver seat 6B can be reduced by using the piezoelectric actuators 5C and 5D of the rear seats 6C and 6D by reducing the control spaces PA and PB, thereby reducing noise in a wider frequency band. Therefore, it is possible to select the high gain computing unit 23 that can further reduce noise.

  Using the above weight function adjustment method, the calculator 23 can be adjusted according to the presence or absence of an occupant as follows. First, the piezoelectric actuators 5A, 5B, 5C, and 5D of the seats 6A, 6B, 6C, and 6D are attached to predetermined positions of the seats 6A, 6B, 6C, and 6D, respectively. When there is a seat where no occupant is present, a piezo actuator corresponding to the seat is used to silence other seats. At this time, by appropriately adjusting the weighting function in the computing unit 23 by the above method, the silencing control effect at the seat where there is no occupant is lowered and the silencing control effect at the seat where the occupant is present is improved. be able to.

  Next, the operation procedure of the above-described noise reduction apparatus will be described with reference to the flowchart of FIG.

  As shown in FIG. 9, the controller 11 of the noise reduction apparatus first inputs an acceleration signal (step S1) and inputs control command signals to the piezoelectric actuators 5A, 5B, 5C, and 5D (step S1 to step S3). S2), an occupant detection signal is input from the occupant detection sensors 7A, 7B, 7C, 7D (step S3).

  Next, in step 4, the controller 11 estimates noise in the passenger compartment by the noise estimation device 21. At this time, the noise estimation device 21 estimates noise in the control spaces PA, PB, PC, PD based on the acceleration signal input in step 1 and the control command signal input in step 2. At this time, the noise estimation device 21 estimates noise for each of the control spaces PA, PB, PC, and PD.

  Next, in step S5, the controller 11 determines the seat where the occupant is present from the occupant detection signal acquired in step S3 by the switching trigger generator 25, and controls the control spaces PA, PB, PC and PD are determined, and control spaces PA, PB, PC and PD to be controlled are selected. The switching trigger generator 25 sets the computing unit 23 that calculates the control command signal by switching the input switch 22 and the output switch 24. For example, a predetermined threshold is set for the occupant detection signal, and it is determined that the occupant is present when the occupant detection signal is higher than the threshold, and the occupant detection signal is lower than the threshold. In that case, it is determined that there are no passengers.

  Next, in step S6, the controller 11 calculates the control command values of the piezoelectric actuators 5A, 5B, 5C, and 5D for reducing noise by the calculator 23, and in step S7, the controller 11 calculates the control command values for the piezoelectric actuators 5A, 5A, 5D. The signals are output to 5B, 5C, and 5D, and the floor panel 1 is vibrated by the piezoelectric actuators 5A, 5B, 5C, and 5D.

  As a result, the noise reduction device can change the control spaces PA, PB, PC, PD for reducing noise by the piezo actuators 5A, 5B, 5C, 5D according to the pattern consisting of the number of passengers and the arrangement, The noise frequency band and noise reduction width to be reduced in the piezo actuators 5A, 5B, 5C, and 5D can be controlled to obtain the optimum noise reduction control effect in the control spaces PA, PB, PC, and PD where the occupants are present.

  The effect of such a noise reduction device will be described with reference to FIGS.

  FIG. 10 shows the frequency-sound pressure characteristics at the ear position when noise reduction control is performed using one piezoelectric actuator for one point of the right ear position in the control space PB of the driver's seat 6B. Note that the measurement of the frequency-sound pressure characteristic detects a pure tone at the ear position for simplicity. According to this frequency-sound pressure characteristic, when one piezo actuator is driven, the characteristic indicated by the dotted line in the figure when one piezo actuator is not driven, as shown by the solid line in the figure. The noise reduction control effect is obtained in a wide frequency band.

  On the other hand, FIG. 11 shows the frequency-sound pressure at the ear position when noise reduction control is performed using two piezoelectric actuators for one point of the right ear position in the control space PB of the driver's seat 6B. Show properties. The two piezoelectric actuators are, for example, a piezoelectric actuator 5B for the driver's seat 6B and a piezoelectric actuator 5A for the passenger seat 6A. According to this frequency-sound pressure characteristic, when two piezo actuators are driven, the noise reduction control effect is improved as compared with the characteristic indicated by the solid line in FIG. 10 in which only one piezo actuator is driven. I understand that. This indicates that by driving two piezo actuators, the gain of the weight function can be increased, and the noise reduction range is expanded. Therefore, by changing the weight function, it is possible to reduce the noise reduction control effect in a space where there is no occupant and to increase the noise reduction control effect in a space where a passenger is present instead.

  FIG. 12 shows weights for widening the frequency band of noise to be reduced when noise reduction control is performed using one piezoelectric actuator for one point of the right ear position in the control space PB of the driver's seat 6B. The frequency-sound pressure characteristic at the ear position when using the calculator 23 in which a function is set is shown. In FIG. 12, frequency bands different for frequency band A and frequency band B are shown separately. According to FIG. 12, when one piezo actuator is driven in contrast to the characteristic indicated by the dotted line in the figure in which one piezo actuator is not driven, a high noise reduction control effect is achieved in one frequency band A. However, in the other frequency band B, it can be seen that a high noise reduction control effect is not obtained.

  On the other hand, FIG. 13 shows a calculation in which a weight function is set to widen the frequency band of noise to be reduced, using two piezo actuators for one point of the right ear position in the control space PB of the driver's seat 6B. The frequency-sound pressure characteristics at the ear position when using the device 23 are shown. According to this frequency-sound pressure characteristic, it can be seen that a high noise reduction control effect is obtained even in the frequency band B when two piezoelectric actuators are driven. As a result, when the number of passengers in the vehicle is less than the capacity, the frequency band of noise that can be reduced can be expanded by driving more piezoelectric actuators in a single control space.

  Moreover, this noise reduction apparatus demonstrated the case where the weighting function of the calculator 23 was set and the noise reduction width and the frequency band were controlled, but when there is a seat where no passenger is present, the control space PA where the passenger is present, PB, PC, and PD may be enlarged. For example, as shown in FIG. 14, when there is an occupant in the driver's seat 6B but no occupant in the rear seat 6D, not only the piezo actuator 5A but also the piezo actuator 5D is driven. As a result, the noise reduction control effect can be obtained for the space composed of the control space PB and the control space PB ′ obtained by enlarging the control space PB. In this case, the controller 11 estimates the noise in the space including the spaces PB and PB ′ by the noise estimation device 21 and is designed so that the noise reduction control effect can be obtained in both the spaces PB and PB ′ by the calculator 23. To do.

  As described above in detail, according to the noise reduction device according to the first embodiment to which the present invention is applied, the presence / absence of an occupant is detected, and a noise reduction control effect can be obtained for a space where the occupant is present. Since the piezo actuators 5A, 5B, 5C, and 5D are driven, it is possible to obtain a noise reduction control effect for higher-frequency road noise. In addition, since the control spaces PA, PB, PC, and PD that obtain the noise reduction control effect depending on the presence or absence of a passenger are switched, a higher noise reduction control effect is obtained in the control spaces PA, PB, PC, and PD where the passengers are present when boarding less than the capacity. Can be achieved.

  Further, according to this noise reduction device, noise at the occupant head position is estimated by the noise estimation device 21, and the control space PA, PB, PC, PD of the occupant head position in the seat where the occupant is present is calculated by the calculator 23. Since the piezo actuators 5A, 5B, 5C, and 5D are driven so as to obtain the noise reduction control effect, the control spaces PA, PB, PC, and PD are limited to obtain a high noise reduction control effect at the occupant head position. be able to.

  Further, according to this noise reduction device, when there is a seat where no occupant is present, the piezo actuator corresponding to the seat is driven so that a noise reduction control effect can be obtained in the control space of the seat where another occupant is present. Therefore, the noise reduction width in the control space where the occupant is present can be further increased.

  Furthermore, according to this noise reduction device, when there is a seat where no occupant is present, the piezo actuator corresponding to the seat can be driven to expand the control space in the seat where the occupant is present. The noise reduction control effect in the space can be further expanded.

  Furthermore, according to this noise reduction device, when there is a seat where no occupant is present, the piezo actuator corresponding to the seat can be driven to expand the frequency band of noise to be reduced in the seat where the occupant is present. Therefore, it is possible to reliably reduce the noise from the low frequency band road noise to the higher frequency band.

[Second Embodiment]
Next, a noise reduction device according to the second embodiment will be described. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The noise reduction device according to the second embodiment reduces noise in the control spaces PA, PB, PC, PD by feedforward control. As shown in FIG. 15, the noise reduction apparatus according to the second embodiment includes a microphone 51 as a sensor for measuring actual noise in the control spaces PA, PB, PC, and PD. The noise in the control space P detected by the microphone 51 is detected by the controller unit 8.

  The controller unit 8 receives an acoustic signal from the microphone 51 by the amplifier 61 and transmits a control command signal to the piezo actuator 5 from the amplifier 62 to amplify an acceleration signal corresponding to the road surface unevenness detected by the acceleration sensor 4. Receive at 63. The controller unit 8 receives the acoustic signal from the microphone 51 via the amplifier 61 by the adaptive law calculation unit 64 and changes the filter coefficient in the adaptive filter 65 according to the acoustic signal.

As shown in FIG. 16, the controller unit 8 includes an adaptive law calculation unit 64 and an adaptive filter 65 configured by a single calculation circuit, and is connected to a transfer function calculation unit 71 and a transfer function calculation unit 72. The transfer function calculation unit 71 calculates a transfer function from the acceleration signal from the acceleration sensor 4 to the noise generated in the control space P, and the transfer function calculation unit 72 controls from the control command signal to the piezo actuator 5. The transfer function up to the noise generated in the space P is calculated. In such a configuration, the noise reduction device uses the acceleration signal obtained by the acceleration sensor 4 as x (n), the noise generated in the control space P due to the disturbance input from the road surface to the vehicle body as y (n), and the microphone 51. The acoustic signal obtained in (1), that is, the acoustic signal that has not been reduced and is detected by the microphone 51 is defined as an error signal e (n). Here, n represents the sample time. Further, the transfer model W (z) of the adaptive filter 65, the transfer function calculating unit 71, the transfer model G (z), and the transfer model C (z) of the transfer function calculating unit 72 are expressed by the following equations 5, 6, and 7, respectively. As shown in.

Here, z ⁻ⁱ in Equation 5, Equation 6, and Equation 7 represents an operator of Z conversion. Note that the filter coefficient w _i in Expression 5 depends on the sampling time n because the adaptive filter 65 is a variable coefficient filter. At this time, the noise signal y (n) in the control space P and the control command signal u (n) to the piezo actuator 5 are calculated as shown in the following equations (8) and (9).

U (n) calculated based on Equations 8 and 9 is input to the piezo actuator 5 as a control command signal.

On the other hand, the adaptive law calculation unit 64 updates the filter coefficient w _i (n) of the adaptive filter 65. The adaptive law calculation unit 64 first defines an evaluation function J as shown in the following Expression 10.

Here, in a generally known LMS (Least Mean Square) algorithm, the adaptive filter 65 is updated so that the evaluation function J is minimized with respect to the filter coefficient w _i (n). The update rule is given by Equation 11 below.

K _e and K _y in Equation 11 are design parameters, and r (n−1) in Equation 11 is defined as Equation 12 below.

By performing such calculation in the adaptive law calculation unit 64, the filter coefficient w _i (n) in the adaptive filter 65 can be updated.

  As shown in FIG. 17, the processing of such a noise reduction device starts with the acceleration signal x (n) from the acceleration sensor 4 and the microphone 51 in response to the predetermined sample time n in step S11. The acoustic (error) signal e (n) is obtained. The acceleration signal x (n) is input to the adaptive filter 65 via the amplifier 63, and the acoustic signal e (n) is input to the adaptive law calculation unit 64 via the amplifier 61.

In the next step S12, the adaptive law calculation unit 64 multiplies the acceleration signal x (n) from the acceleration sensor 4 by the filter coefficient w _i (n), and in step S13, the acoustic signal e (n) from the microphone 51. Is used to calculate the filter coefficient w _i (n). At this time, the adaptive law calculation unit 64 obtains the updated filter coefficient w _i (n) by performing the calculation of the above-described Expression 11 and Expression 12.

In the next step S14, the filter coefficient w _i (n) calculated in step S13 is sent from the adaptive law calculation unit 64 to the adaptive filter 65, the filter coefficient w _i (n) in the adaptive filter 65 is updated, and the filter coefficient w _The control command signal u (n) is calculated by performing the calculation of Equation 9 using _i (n). As a result, the control command signal u (n) is supplied to the piezo actuator 5 via the amplifier 62.

  As in the noise reduction device according to the second embodiment, even when the control command signal u (n) is generated by the feedforward type calculation and the piezo actuator 5 is controlled, the same as described above. In addition, noise at the occupant head position can be effectively reduced.

[Third Embodiment]
Next, a noise reduction device according to a third embodiment to which the present invention is applied will be described. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The noise reduction device according to the third embodiment is a noise reduction device that performs a feedforward type operation to generate a control command signal. As shown in FIG. 18, two acceleration sensors 4A are used instead of the microphone 51. , 4B are provided on the floor panel 1, and a noise estimation device 86 is added to the controller unit 8 shown in FIG.

  The noise estimation device 86 is connected to the acceleration sensor 4B via the amplifier 82 and is connected to the occupant detection sensors 7A and 7B via the amplifiers 81 and 83, and inputs the control command signal calculated by the adaptive filter 65. . The noise estimation device 86 estimates noise in the control space P using the acceleration signal from the acceleration sensor 4B, the occupant detection signals from the occupant detection sensors 7A and 7B, and the control command signal. The noise estimation device 86 has the same configuration as that shown in FIG. 16, for example, and sends the estimated noise to the adaptive law calculation unit 64.

  The filter coefficient of the adaptive filter 65 is changed by the adaptive law calculation unit 64 described above. The adaptive filter 65 inputs the acceleration signal from the acceleration sensor 4 </ b> A via the amplifier 85. The adaptive filter 65 receives the acceleration signal from the acceleration sensor 4A as a signal representing disturbance in the floor panel 1, and calculates a control command signal for reducing noise in the control space P based on the disturbance signal.

As shown in FIG. 19, in such a noise reduction apparatus, first, acceleration signals from the acceleration sensors 4A and 4B are inputted by the controller unit 8 in step S21, and in step S22, the acceleration sensor 4B is inputted by the adaptive law calculation unit 64. Is multiplied by a filter coefficient w _i (n), and the noise estimation device 86 uses the acceleration signal from the acceleration sensor 4A and the control command signal output from the adaptive filter 65 in step S23. To estimate noise.

In the next step S24, the adaptive law calculation unit 64 uses the noise e (n) estimated in step S23 and uses Equation 11 and Equation 12 to minimize the evaluation function shown in Equation 13 below. An operation is performed to calculate a new filter coefficient w _i (n).

Here, s _i in Expression 13 is a variable indicating the presence or absence of an occupant in each seat according to the occupant detection signal, and is “1” when there is an occupant, and “0” when there is no occupant. By using such an evaluation function, a greater silent control effect can be obtained in the control space P in the seat where the passenger is present.

In the next step S25, the filter coefficient w _i (n) of the adaptive filter 65 is updated with the filter coefficient w _i (n) obtained in step S24.

In the next step S 26, the adaptive filter 65 calculates the control command signal u (n) by performing the calculation of the above equation 9 using the updated filter coefficient w _i (n), and the piezoelectric filter via the amplifier 84. The actuator 5 is supplied.

  Thus, even when the control command signal u (n) is generated by the feedforward type operation to control the piezo actuator 5, noise at the occupant head position can be effectively reduced as in the case described above. .

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

It is a perspective view for demonstrating the principle which reduces the noise in control space with the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a block diagram which shows the structure of the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a block diagram which shows the structure of the controller in the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a block diagram which shows the structure of the noise estimation apparatus in the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. This is the frequency characteristic of the transfer function used in the control command → sound pressure calculation unit. It is a block diagram explaining the design method of a calculator in the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a figure which shows the relationship between the frequency obtained by changing the calculation parameter of a calculator, a phase, and the sound pressure of the noise which can be reduced in the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is another figure which shows the relationship between the frequency obtained by changing the calculation parameter of a calculator, a phase, and the sound pressure of the noise which can be reduced in the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a flowchart which shows the process sequence of the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a comparative example with respect to the effect of the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied, Comprising: It is a figure which shows the frequency-sound pressure characteristic when one piezoelectric actuator is driven. It is a figure which shows the effect of the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied, and is a figure which shows the frequency-sound pressure characteristic when two piezo actuators are driven. It is a comparative example with respect to the effect of the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied, Comprising: It is a figure which shows the frequency-sound pressure characteristic in a different frequency band when one piezoelectric actuator is driven. It is a figure which shows the effect of the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied, and is a figure which shows the frequency-sound pressure characteristic in a different frequency band when two piezo actuators are driven. It is a side view explaining the operation | movement which expands control space in the noise reduction apparatus which concerns on 1st Embodiment to which this invention is applied. It is a block diagram which shows the structure of the controller in the noise reduction apparatus which concerns on 2nd Embodiment to which this invention is applied. It is a block diagram which shows the structure of the controller unit in the noise reduction apparatus which concerns on 2nd Embodiment to which this invention is applied. It is a flowchart which shows the process sequence in the noise reduction apparatus which concerns on 2nd Embodiment to which this invention is applied. It is a block diagram which shows the structure of the noise reduction apparatus which concerns on 2nd Embodiment to which this invention is applied. It is a flowchart which shows the process sequence of the noise reduction apparatus which concerns on 3rd Embodiment to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Floor panel 2 Tire 3 Engine 4 Acceleration sensor 5A, 5B, 5C, 5D Piezo actuator 6A, 6B, 6C, 6D Seat 7A, 7B, 7C, 7D Crew detection sensor 8 Controller unit 11 Controller 21 Noise estimation device 22 Input switch 23 Arithmetic unit 24 Output switch 25 Trigger generator 31 Control command → Vibration calculation unit 32, 35 Adder 33 Vibration → Sound pressure calculation unit 34 Control command → Sound pressure calculation unit 41 Calculator 42 Transfer function model 51 Microphone 64 Adaptive law calculation unit 65 Adaptive Filter 71, 72 Transfer Function Calculation Unit 86 Noise Estimation Device

Claims (8)

Vibration detecting means for detecting vibration of the vehicle body;
Noise reduction means for generating vibration or sound provided in each seat of the vehicle to reduce noise in the passenger compartment;
Control command value calculating means for calculating a control command value for controlling vibration or sound generated by the noise reducing means according to the vibration detected by the vibration detecting means;
Occupant detection means for detecting the presence or absence of an occupant in each seat,
The control command value calculation means is
While adjusting the control command value so as to obtain a silencing control effect in a space where an occupant detected by the occupant detection means is present, the vibration or sound generated by the noise reduction means is controlled ,
When there is a seat determined by the occupant detection means that there is no occupant, using the noise reduction means corresponding to this seat, in the space where it is determined that there is an occupant, the noise reduction control effect is achieved. A noise reduction device , wherein the control command value is adjusted so as to enlarge an obtained region . Vibration detecting means for detecting vibration of the vehicle body;
Noise reduction means for generating vibration or sound provided in each seat of the vehicle to reduce noise in the passenger compartment;
Control command value calculating means for calculating a control command value for controlling vibration or sound generated by the noise reducing means according to the vibration detected by the vibration detecting means;
Occupant detection means for detecting the presence or absence of an occupant in each seat,
The control command value calculation means is
While adjusting the control command value so as to obtain a silencing control effect in a space where an occupant detected by the occupant detection means is present, the vibration or sound generated by the noise reduction means is controlled,
When there is a seat determined by the occupant detection means that there is no occupant, the noise to be reduced in the space near the seat where the occupant is determined using the noise reduction means corresponding to the seat The noise reduction device is characterized in that the control command value is adjusted so as to expand the frequency band . The occupant detection means is an occupant head detection means for detecting an occupant head position,
2. The control command value calculating means adjusts the control command value so that a silencing control effect can be obtained in a space where an occupant head position detected by the occupant head detecting means exists. Or the noise reduction apparatus in any one of Claim 2 . 4. The control command value calculating means adjusts the control command value so as to increase a noise reduction amount in a space where an occupant exists detected by the occupant detection means. or noise reduction device according to item 1. When reducing noise in the passenger compartment by generating vibration or sound,
Detecting vibrations of the vehicle body and detecting the presence or absence of an occupant in the passenger compartment;
  Adjusting a control command value supplied to noise reduction means provided in each seat of the vehicle to generate vibration or sound so that a noise reduction control effect is obtained in a space where the detected occupant exists;
Supplying the adjusted control command value to the noise reduction means,
In the step of adjusting the control command value,
When there is a seat determined to have no occupant, the noise reduction means corresponding to this seat is used to expand the area where the noise reduction control effect can be obtained in the space determined to have an occupant. Thus, the noise reduction method characterized by adjusting the control command value. When reducing noise in the passenger compartment by generating vibration or sound,
Detecting vibrations of the vehicle body and detecting the presence or absence of an occupant in the passenger compartment;
Adjusting a control command value supplied to noise reduction means provided in each seat of the vehicle to generate vibration or sound so that a noise reduction control effect is obtained in a space where the detected occupant exists;
Supplying the adjusted control command value to the noise reduction means ,
In the step of adjusting the control command value,
When there is a seat determined to have no occupant, the noise reduction means corresponding to this seat is used to expand the frequency band of noise to be reduced in the space near the seat that is determined to have an occupant. And adjusting the control command value . In the step of acquiring the occupant position information, the occupant head position is detected,
In the step of adjusting the control command value, according to claim 5 or claim, characterized in that adjusting the control command value as noise reduction control effect is obtained in the space where the detected occupant head position exists 6 The noise reduction method according to any one of the above. In the step of adjusting the control command value, any one of the claims 5 to 7, wherein adjusting the control command value so as to increase the noise reduction amount in the detected existing space of the passenger The noise reduction method according to item .

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