CN107351741A - A kind of active noise reduction headrest of automotive seat - Google Patents

Abstract

A kind of active noise reduction headrest of presently disclosed automotive seat, the active noise reduction headrest include headrest body, in addition to：Two pivoted arms, 2M reference microphone, 2N error microphone, active noise reduction controller and two loudspeakers.Compared with prior art, the active noise reduction headrest of automotive seat disclosed in this invention is higher by a series of degree of accuracy of incoherent optimal noise control modes obtained with reference to acoustic mode S [n], it can more match with the noise pattern in cabin, the echo signal Y [n] and noise at headrest that are sent further according to optimal noise control mode matching degree are also higher, so as to realize the wideband noise reduction to specific region noise in cabin, noise reduction is more obvious.

Description

A kind of active noise reduction headrest of car seat

technical field

The invention relates to the technical field of automobiles, in particular to an active noise reduction headrest of an automobile seat.

Background technique

With the rapid development of modern industry, transportation and aviation, the number of car ownership is also increasing. Moreover, along with the improvement of people's requirements for the ride comfort of automobiles, the strengthening of environmental protection awareness and the development of the automobile industry, the noise control of automobiles has been paid more and more attention by people.

At present, the control of noise in the car cabin is mainly based on passive control. The passive control of the noise in the car cabin is mainly through optimizing the structural design of the car and applying sound-absorbing materials to the car for physical noise reduction, so as to achieve the control of the noise in the car cabin. This passive control of noise in the car cabin has an obvious shielding effect on high-frequency noise, but the control effect on low- and middle-frequency noise is not obvious.

With the development of automobile noise reduction technology, the active control of automobile cabin noise is also more and more popular. The principle of active control of noise in the car cabin is: all sounds are composed of a certain frequency spectrum, and a sound can be found whose spectrum is exactly the same as the noise in the car cabin to be eliminated, but the phase is just opposite (180° difference). The noise in the car cabin can be completely offset. The key to its technology is how to get the sound that cancels the noise.

Now, although the active control of the noise in the car cabin has been researched and applied to a certain extent, the current active control technology of the noise in the car cabin is not mature enough, and the noise control effect is not ideal.

Contents of the invention

The object of the present invention is to provide an active noise reduction headrest of a car seat to solve the above problems.

The present invention solves technical problem and adopts following technical scheme:

An active noise reduction headrest of a car seat, the active noise reduction headrest includes a headrest main body, and further includes:

Two rotating arms, the two rotating arms are symmetrically hinged on both sides of the main body of the headrest;

2M reference microphones, the 2M reference microphones are symmetrically arranged on the front of the two rotating arms, and are used to collect the main noise x[n], where M is an integer not less than 1;

2N error microphones, the 2N error microphones are symmetrically arranged on the back of the two rotating arms and the main body of the headrest, and are used to collect the residual noise e[n] after noise control at the headrest, where N is not less than 1 integer;

an active noise reduction controller, the active noise reduction controller is connected to the reference microphone and the error microphone respectively, and is used to receive the main noise x[n] and the residual noise e[n], and extract A series of incoherent reference acoustic modes S[n], and then generate an optimal noise control mode based on a series of incoherent reference acoustic modes S[n] and residual noise e[n];

Two loudspeakers, the two loudspeakers are arranged symmetrically inside the two rotating arms and connected to the active noise reduction controller for receiving the optimal noise control mode and sending out target signals according to the optimal noise control mode Y[n] to reduce the noise at the headrest.

Preferably, the active noise reduction controller includes:

A reference acoustic mode extraction unit, the reference acoustic mode extraction unit is connected to the reference microphone for receiving the main noise x[n], and extracting a series of irrelevant reference acoustic modes S[n] according to the main noise x[n] ];

A noise control mode prediction unit, the noise control mode prediction unit is connected to the error microphone and the reference acoustic mode separation subunit respectively, and is used to receive residual noise e[n] and a series of irrelevant reference acoustic modes S[n] , and generate an optimal noise-control pattern based on the residual noise e[n] and a set of incoherent reference acoustic patterns S[n].

Preferably, the reference acoustic mode extraction unit includes:

The reference acoustic mode extraction subunit is used to receive the main noise source noise x[n], and apply the extraction function E ^-1 to the main noise x[n] to extract a series of reference acoustic mode Pattern S'[n]:

S'[n]=E ^-1 (x[n]);

The reference acoustic mode separation subunit, the reference acoustic mode separation subunit and the reference acoustic mode extraction subunit are used to receive a series of reference acoustic modes S'[n], and apply the comparison function D to a series of reference acoustic modes In pattern S'[n]:

D(S'[n])=I[S'[1]...S'[k]],

Use the automatic adjustment algorithm to automatically adjust the extraction function E ^-1 , and output a series of irrelevant The reference acoustic model S[n] of .

Preferably, the noise control mode prediction unit includes:

A path transfer function analysis subunit, the path transfer function analysis subunit is used to analyze the path transfer function of the target signal from the loudspeaker to the error microphone, and obtain the predicted path transfer function H[n] for the noise control mode;

An adaptive filter, the adaptive filter is respectively connected with the path transfer function analysis subunit, the error microphone and the reference acoustic mode extraction unit, and is used to receive the predicted path transfer function H[n] for the noise control mode , residual noise e[n] and a series of incoherent reference acoustic modes S[n], and based on the FX-LMS algorithm, by adjusting the filter weight coefficient calculation formula w[n+1]=w[n]+μ· H[n] and μ in e[n]·H[n]·S[n] continuously update the weight coefficient w until the convergence factor μ when the residual noise e(n) converges is the smallest, and the optimal noise is output Control mode Y[n]=w·S[n].

Preferably, M=2.

Preferably, N=3.

It can be seen that the active noise reduction headrest of the car seat disclosed in the present invention collects the main noise x[n] at the headrest of the car seat through the reference microphones symmetrically arranged on the front of the two rotating arms. The error microphone on the back of the rotating arm and the main body of the headrest collects the residual noise e[n] after noise control at the headrest, and then the active noise reduction controller receives the main noise x[n] and the residual noise e[n], and calculates the residual noise e[n] according to The main noise x[n] extracts a series of incoherent reference acoustic modes S[n], and then generates the optimal noise control mode based on a series of incoherent reference acoustic modes S[n] and residual noise e[n], and finally Then, the speakers arranged symmetrically on the front of the two booms send out the target signal Y[n] according to the optimal noise control mode to reduce the noise at the headrest. Compared with the prior art, the optimal noise control mode obtained by the active noise reduction headrest of the car seat disclosed in the present invention through a series of irrelevant reference acoustic modes S[n] has higher accuracy, and is more compatible with The noise pattern in the cabin is matched, and the target signal Y[n] sent according to the optimal noise control mode has a higher matching degree with the noise at the headrest, so as to achieve broadband noise reduction for noise in a specific area in the cabin effect, the noise reduction effect is more obvious.

In addition, the two rotating arms are symmetrically hinged on both sides of the main body of the headrest, and the distance between the microphone and the loudspeaker and the human ear can be manually adjusted as required, thereby effectively improving the monitoring accuracy of the noise near the headrest and realizing the maximum noise near the headrest. Limit noise reduction.

Description of drawings

Fig. 1 is a schematic diagram of the front structure of an active noise reduction headrest of a car seat disclosed by the present invention;

Fig. 2 is a schematic diagram of the back structure of an active noise reduction headrest of a car seat disclosed by the present invention;

Fig. 3 is a diagram of the noise distribution at the human ear before and after the active noise reduction headrest of the car seat disclosed by the present invention is opened.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The technical solutions of the present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

The embodiment of the present invention discloses an active noise reduction headrest for a car seat. As shown in Fig. 1 and Fig. 2, the active noise reduction headrest includes a headrest main body, and further includes:

Two rotating arms, the two rotating arms are symmetrically hinged on both sides of the headrest main body, relative to the headrest main body, the relative position between the rotating arm and the headrest main body is adjustable, that is, in actual work , The relative position between the rotating arm and the human ear is adjustable.

2M reference microphones, the 2M reference microphones are arranged symmetrically on the front of the two rotating arms, and are used to collect the main noise x[n], where M is an integer not less than 1. In this embodiment, the M=2, that is, four reference microphones are included in this embodiment. In addition, M can also be 1, 3, 4, etc. The selection of M value is related to the area of the rotating arm and the required accuracy, so the selection of M value needs to be determined according to the actual situation. In addition, the main noise can be understood as the engine compartment noise at different speeds, the low- and middle-frequency noise radiated by the car audio device, and the road noise under different road conditions near the headrest when the car is running. Noise x[n]. Among them, x[n] is a matrix composed of n discrete time samples of the main noise. The acoustic properties of the dominant noise include amplitude, phase, and frequency.

2N error microphones, the 2N error microphones are symmetrically arranged on the back of the two rotating arms and the main body of the headrest, and are used to collect the residual noise e[n] after noise control at the headrest, where N is not less than 1 integer. In this embodiment, the N=3, that is, 6 error microphones are included in this embodiment. In addition, N can also be a value such as 1, 2, 4, etc. Like the value of M, the selection of the value of N is related to the area of the arm and the required accuracy, so the selection of the value of N needs to be determined according to the actual situation. In addition, the residual noise can be understood as the residual noise e[n] is actually the residual noise after the noise control at the headrest of the car seat, and can also be understood as the noise that the person sitting on the car seat can feel noise. Residual noise e[n] is a matrix composed of n discrete time samples of residual noise.

an active noise reduction controller, the active noise reduction controller is connected to the reference microphone and the error microphone respectively, and is used to receive the main noise x[n] and the residual noise e[n], and extract A series of incoherent reference acoustic patterns S[n], and then generate an optimal noise control pattern based on a series of incoherent reference acoustic patterns S[n] and residual noise e[n]. In this embodiment, the active noise reduction controller is arranged under the car seat, but the present invention does not limit the specific installation location. Wherein, the active noise reduction controller includes:

A reference acoustic mode extraction unit, the reference acoustic mode extraction unit is connected to the reference microphone for receiving the main noise x[n], and extracting a series of irrelevant reference acoustic modes S[n] according to the main noise x[n] ]. Further, the reference acoustic mode extraction unit includes:

The reference acoustic mode extraction subunit is used to receive the main noise source noise x[n], and apply the extraction function E ^-1 to the main noise x[n] to extract a series of reference acoustic mode Pattern S'[n]:

S'[n]=E ^-1 (x[n]), wherein, the extraction function E ^-1 is a linear mapping function with a memory function, and performs a convolution operation, and the acoustic pattern mainly includes three elements of the noise signal, That is, amplitude, phase and frequency information. There is a mapping relationship between the main noise x[n] matrix elements and a series of reference acoustic mode S'[n] matrix elements.

A reference acoustic mode separation subunit connected to the reference acoustic mode extraction subunit for receiving a series of reference acoustic modes S'[n] and applying the comparison function D to a series of reference In acoustic mode S'[n]:

D(S'[n])=I[S'[1]...S'[k]],

Use the automatic adjustment algorithm to automatically adjust the extraction function E ^-1 , and output a series of irrelevant The reference acoustic model S[n] of . Among them, the process of automatically adjusting the extraction function E ^-1 using the automatic adjustment algorithm is as follows:

(1) If I>0, then adjust E ^-1 , change the mapping relationship between x[n] and S'[n], and continue to judge;

(2) If I=0, use E ⁻¹ as the extraction function of the extraction process.

The series of incoherent reference acoustic modes S[n] are the most representative acoustic modes separated from the preset main noise sources. The active noise reduction headrest disclosed in this embodiment applies the extraction function to multiple reference signal inputs of multiple types of sound sources, and optimizes the extraction function through an adaptive adjustment algorithm, which can effectively ensure the accuracy of the extracted acoustic mode.

A noise control mode prediction unit, the noise control mode prediction unit is connected to the error microphone and the reference acoustic mode separation subunit respectively, and is used to receive residual noise e[n] and a series of irrelevant reference acoustic modes S[n] , and generate an optimal noise-control pattern based on the residual noise e[n] and a set of incoherent reference acoustic patterns S[n]. Further, the noise control mode prediction unit includes:

Path transfer function analysis subunit, the path transfer function analysis subunit is used to analyze the path transfer function of the target signal from the loudspeaker to the error microphone, and obtain the path transfer function H[n] used for noise control mode prediction, the process can It is understood that the length of time corresponding to n sampling points is a period of time. If the system includes E speakers and F error microphones, EF transfer paths are formed between the speakers and the error microphones. At this time, analyze the jth path transfer function H [j] Whether the residual noise e(n) converges within n sampling points: (1) if it converges, use H[j] to predict the noise control mode; (2) if it does not converge, abandon H[j ], repeat the above steps to analyze H[j+1];

An adaptive filter, the adaptive filter is respectively connected to the path transfer function analysis subunit, the error microphone and the reference acoustic mode extraction unit, and is used to receive the path transfer function H[n] for noise control mode prediction, Residual noise e[n] and a series of incoherent reference acoustic modes S[n], and based on the FX-LMS algorithm, by adjusting the filter weight coefficient calculation formula w[n+1]=w[n]+μ e [n]·H[n]·S[n] in H[n] and μ to continuously update the weight coefficient w until the convergence factor μ when the residual noise e(n) converges is the smallest, and the optimal noise control is output Pattern Y[n]=w·S[n].

The optimal noise control mode Y[n] can best match a series of incoherent reference acoustic modes S[n], that is, modes with the same amplitude and frequency but opposite phases, so as to effectively integrate with the main noise offset each other to achieve the best noise reduction effect.

Two loudspeakers, the two loudspeakers are arranged symmetrically inside the two rotating arms and connected to the active noise reduction controller for receiving the optimal noise control mode and sending out target signals according to the optimal noise control mode Y[n] to reduce the noise at the headrest.

Since the optimal noise control mode Y[n] can best match a series of irrelevant reference acoustic modes S[n], the target signal (sound) emitted according to the optimal noise control mode can effectively offset the main Noise, to achieve the best noise reduction effect.

It can be seen that the active noise reduction headrest of the car seat disclosed in the embodiment of the present invention collects the main noise x[n] at the headrest of the car seat through the reference microphones symmetrically arranged on the front of the two rotating arms. The error microphones on the back of the two rotating arms and the main body of the headrest collect the residual noise e[n] after noise control at the headrest, and then the active noise reduction controller receives the main noise x[n] and residual noise e[n], And extract a series of incoherent reference acoustic modes S[n] according to the main noise x[n], and then generate an optimal noise control mode based on a series of incoherent reference acoustic modes S[n] and residual noise e[n] , and finally the target signal Y[n] is sent out according to the optimal noise control mode to reduce the noise at the headrest through the speakers symmetrically arranged on the front of the two booms. Compared with the prior art, the optimal noise control mode obtained by the active noise reduction headrest of the car seat disclosed in the present invention through a series of irrelevant reference acoustic modes S[n] has higher accuracy, and is more compatible with The noise pattern in the cabin is matched, and the target signal Y[n] sent according to the optimal noise control mode has a higher matching degree with the noise at the headrest, so as to achieve broadband noise reduction for noise in a specific area in the cabin effect, the noise reduction effect is more obvious.

In addition, the two rotating arms are symmetrically hinged on both sides of the main body of the headrest, and the distance between the microphone and the loudspeaker and the human ear can be manually adjusted as required, thereby effectively improving the monitoring accuracy of the noise near the headrest and realizing the maximum noise near the headrest. Limit noise reduction.

Moreover, in this embodiment, according to a series of irrelevant reference acoustic modes and residual noise in the main noise, the filter weight coefficients are adaptively optimized to output an optimal noise control mode with a high degree of matching with the reference acoustic modes, and then according to the The optimal noise control mode emits a target sound signal corresponding to the optimal noise control mode to achieve maximum noise reduction at the headrest of the car seat.

Furthermore, the active noise reduction headrest of the car seat disclosed in this embodiment has a wide range of applications and is not limited to vehicle types, and is generally applicable.

As shown in Figure 3, this embodiment further discloses that at a certain vehicle speed, before (Before) and after (After) the active noise reduction controller of the active noise reduction headrest of the car seat is turned on, the left and right ear By comparing the noise spectrums measured separately, it can be seen that the active noise reduction solution provided by the present invention has a significant active noise reduction effect in a wide frequency range.

Finally, it should be noted that: the symmetrical arrangement in this embodiment not only refers to mutual symmetry in spatial positions, but also an equal relationship in terms of the number of arrangements on both sides. Moreover, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be applied to the foregoing embodiments The technical solutions described in the examples are modified, or some of the technical features are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (6)

1. A kind of active noise reduction headrest of car seat, described active noise reduction headrest comprises headrest main body, is characterized in that, also comprises: Two rotating arms, the two rotating arms are symmetrically hinged on both sides of the main body of the headrest; 2M reference microphones, the 2M reference microphones are symmetrically arranged on the front of the two rotating arms, and are used to collect the main noise x[n], where M is an integer not less than 1; 2N error microphones, the 2N error microphones are symmetrically arranged on the back of the two rotating arms and the main body of the headrest, and are used to collect the residual noise e[n] after noise control at the headrest, where N is not less than 1 integer; an active noise reduction controller, the active noise reduction controller is connected to the reference microphone and the error microphone respectively, and is used to receive the main noise x[n] and the residual noise e[n], and extract A series of incoherent reference acoustic modes S[n], and then generate an optimal noise control mode based on a series of incoherent reference acoustic modes S[n] and residual noise e[n]; Two loudspeakers, the two loudspeakers are arranged symmetrically inside the two rotating arms and connected to the active noise reduction controller for receiving the optimal noise control mode and sending out target signals according to the optimal noise control mode Y[n] to reduce the noise at the headrest. 2. The active noise reduction headrest of the car seat according to claim 2, wherein the active noise reduction controller comprises: A reference acoustic mode extraction unit, the reference acoustic mode extraction unit is connected to the reference microphone for receiving the main noise x[n], and extracting a series of irrelevant reference acoustic modes S[n] according to the main noise x[n] ]; A noise control mode prediction unit, the noise control mode prediction unit is connected to the error microphone and the reference acoustic mode separation subunit respectively, and is used to receive residual noise e[n] and a series of irrelevant reference acoustic modes S[n] , and generate an optimal noise-control pattern based on the residual noise e[n] and a set of incoherent reference acoustic patterns S[n]. 3. The active noise reduction headrest of the car seat according to claim 2, wherein the reference acoustic mode extraction unit comprises: The reference acoustic mode extraction subunit is used to receive the main noise source noise x[n], and apply the extraction function E ^-1 to the main noise x[n] to extract a series of reference acoustic mode Pattern S'[n]: S'[n]=E ^-1 (x[n]); The reference acoustic mode separation subunit, the reference acoustic mode separation subunit and the reference acoustic mode extraction subunit are used to receive a series of reference acoustic modes S'[n], and apply the comparison function D to a series of reference acoustic modes In pattern S'[n]: D(S'[n])=I[S'[1]...S'[k]], Use the automatic adjustment algorithm to automatically adjust the extraction function E ^-1 , and output a series of irrelevant The reference acoustic model S[n] of . 4. The active noise reduction headrest of the car seat according to claim 2, wherein the noise control mode prediction unit comprises: A path transfer function analysis subunit, the path transfer function analysis subunit is used to analyze the path transfer function of the target signal from the loudspeaker to the error microphone, and obtain the predicted path transfer function H[n] for the noise control mode; An adaptive filter, the adaptive filter is respectively connected with the path transfer function analysis subunit, the error microphone and the reference acoustic mode extraction unit, and is used to receive the predicted path transfer function H[n] for the noise control mode , residual noise e[n] and a series of incoherent reference acoustic modes S[n], and based on the FX-LMS algorithm, by adjusting the filter weight coefficient calculation formula w[n+1]=w[n]+μ· H[n] and μ in e[n]·H[n]·S[n] continuously update the weight coefficient w until the convergence factor μ when the residual noise e(n) converges is the smallest, and the optimal noise is output Control mode Y[n]=w·S[n]. 5. The active noise reduction headrest of the car seat according to claim 1, wherein M=2. 6. The active noise reduction headrest of the car seat according to claim 1, wherein N=3.