Acoustic-magnetic fusion signal sensing demodulation method and device based on magnetoelectric heterostructure

Abstract

The invention discloses an acoustic-magnetic coexistence signal sensing demodulation method and device based on a magnetoelectric heterostructure, and the device employs a control circuit (MCU) to generate a modulation square wave DC bias magnetic field for the magnetoelectric heterostructure, so as to change the responsivity of the magnetoelectric heterostructure to a magnetic signal. Meanwhile, a control circuit (MCU) synchronously controls the sampling frequency and time delay of the acquisition card so as to acquire two different output electric signals of the magnetoelectric heterostructure in one period of the modulation bias magnetic field. Carrying out odd-even grouping and Fourier transform on the collected electric signals, establishing two weighted linear combination frequency domain equations of the electric signals and the acoustic and magnetic signals based on frequency response coefficients of the magnetoelectric heterostructure to the acoustic and magnetic signals, connecting the two frequency domain equations in parallel, and decoupling frequency domain characteristics of the acoustic and magnetic signals by adopting an elimination method; and finally, inverse Fourier transform is carried out to restore the magnetic signal and the sound signal in the time domain, so that sensing and demodulation of the sound and magnetic signals can be completed. The device realizes decoupling and sensing of acoustic and magnetic multi-physical fields, has the characteristics of simple structure, high sensitivity and the like, and is easy to realize.

Description

Technical Field

[0001] The present invention belongs to the field of multi - physical - field sensing, and particularly relates to a method and device for acoustic - magnetic co - existing signal sensing based on a magnetoelectric heterostructure. Background Art

[0002] A magnetoelectric heterostructure is a composite structure formed by magnetostrictive materials and piezoelectric materials in a specific manner. Its working principle is based on the "magnetic - elastic - electric" elastic coupling effect between the two materials, thereby realizing the magnetoelectric effect and the mutual conversion between magnetic signals and electrical signals. In the field of magnetic field sensing, magnetoelectric heterostructures have become an important sensing technology due to their advantages such as low cost, small volume, high sensitivity, high temperature stability, low power consumption, and wide bandwidth, and have important research value and application significance in fields such as position and motion detection, navigation, security systems, medical applications, and industrial automation. When a magnetoelectric heterostructure is used for magnetic field sensing, it usually needs to work under a certain DC bias magnetic field, and different DC bias magnetic fields will change the response degree of the magnetoelectric heterostructure to magnetic signals.

[0003] In addition to magnetic field sensing, magnetoelectric heterostructures also have application potential in the field of sound signal sensing. The principle of its sound signal sensing is as follows: when a sound signal (such as a sound wave in the air) acts on a magnetoelectric heterostructure, the mechanical vibration of the sound wave triggers the piezoelectric effect of the piezoelectric material in the magnetoelectric heterostructure, that is, the piezoelectric material deforms under the action of mechanical vibration, thereby causing changes in the electric field or charge distribution, and finally completing the conversion from mechanical vibration to an electrical signal.

[0004] By synchronously detecting the acoustic signal and magnetic signal of the same target, more information can be obtained than that of a single physical field (such as only the acoustic field or only the magnetic field). Therefore, it is of great significance to carry out independent sensing and demodulation of acoustic - magnetic multi - physical quantities. However, in nature, the generation mechanisms of the acoustic field and the magnetic field are usually independent of each other, and they may co - exist within a certain space - time range. When sensing based on a magnetoelectric heterostructure, what is often detected is an acoustic - magnetic fusion co - existing signal. This co - existing signal contains information of both sound signals and magnetic signals. How to independently demodulate the sound signal and the magnetic signal from the acoustic - magnetic fusion signal has become a technical problem to be solved urgently at present. Summary of the Invention

[0005] In view of the above, the present invention provides a method and device for acoustic - magnetic fusion co - existing signal sensing based on a magnetoelectric heterostructure. This method is applicable to the detection of acoustic - magnetic fusion signals and can realize the decoupling of sound signals and magnetic signals.

[0006] A method and device for sensing and demodulating acoustic-magnetic fusion signals based on a magnetoelectric heterostructure, characterized in that it includes a sensing module and a control module (MCU); wherein, the sensing module is used to sense the acoustic-magnetic fusion signal and output an electrical signal, and the control module (MCU) is used to generate a modulated square wave level signal and control the signal sampling frequency and delay, and at the same time realize the decoupling process of the acoustic-magnetic fusion signal. This solution utilizes the characteristic that the magnetoelectric heterostructure changes the response degree to magnetic signals under different DC bias magnetic fields while keeping the response degree to sound signals consistent, and combines the acoustic-magnetic fusion signal demodulation algorithm to realize the decoupling of sound signals and magnetic signals in the coexisting acoustic-magnetic signals.

[0007] Further, the sensing module includes a magnetoelectric heterostructure (101) and a solenoid (102), wherein:

[0008] The magnetoelectric heterostructure (101) is used to respond to the acoustic-magnetic fusion signal and output an electrical signal;

[0009] The solenoid (102) is used to provide a DC bias magnetic field.

[0010] Further, the magnetoelectric heterostructure (101) is formed by bonding two upper and lower layers of amorphous soft magnetic alloy (201) and seven middle piezoelectric ceramic lead zirconate titanate-based materials (203) with epoxy glue into a layered structure.

[0011] Further, the amorphous soft magnetic alloy (201) is magnetized along the length direction, and the piezoelectric ceramic lead zirconate titanate-based material (203) is polarized along the thickness direction and arranged alternately in a form with opposite adjacent polarization directions.

[0012] Further, polyimide film (202) is used between the amorphous soft magnetic alloy (201) and the piezoelectric ceramic lead zirconate titanate-based material (203) to achieve electrical insulation. The surface electrode of the piezoelectric ceramic lead zirconate titanate-based material (203) is a silver electrode (204), and the copper foil (205) and the wire (206) are fixed on the electrode by conductive silver glue to realize electrical series connection of the electrodes and electrical signal transmission respectively.

[0013] Further, the control module (MCU) includes a control circuit (MCU) (103), a signal source (104), an electrical amplifier (105), and an acquisition card (106), wherein:

[0014] The control circuit (MCU) (103) is used to control the output level of the signal source (104) and the sampling frequency and delay of the acquisition card (106);

[0015] The signal source (104) is used to generate a modulated square wave signal to control the change of the DC bias magnetic field;

[0016] The electric amplifier (105) is used to amplify the electric signal output by the magneto-electric heterostructure (101).

[0017] The acquisition card (106) is used to convert the electrical signal into a digital signal to perform acoustic-magnetic coexistence signal demodulation.

[0018] Furthermore, the frequency of the square wave signal is more than ten times greater than the highest frequency of the sensing signal.

[0019] Furthermore, the sampling frequency is twice the frequency of the square wave signal, and the sampling delay is a time position when the sampling point is located at the middle point of the high and low levels of the modulated square wave signal.

[0020] Furthermore, for sensing and demodulating the magnetic signal to be measured being H(t) and the sound signal to be measured being A(t) (the spectrum of the magnetic signal is H(f), and the spectrum of the sound signal is A(f)), the acquisition card (106) comprises the following digital signal processing module:

[0021] An odd-even grouping module (301) is used to perform odd-even grouping on the collected electrical signals to obtain odd-group signals Z1(N) and even-group signals Z2(N), wherein the odd-group signals Z1(N) are output electrical signals of the electrical amplifier (105) when the magnetoelectric heterostructure (101) has a DC bias magnetic field, and the even-group signals Z1(N) are output electrical signals of the electrical amplifier (105) when the magnetoelectric heterostructure (101) has no DC bias magnetic field;

[0022] A Fourier transform module (302), used for performing Fourier transform on Z1(N) and Z2(N) to obtain frequency spectra Z1(f) and Z2(f);

[0023] A frequency domain equation establishment module (303) is used to establish a weighted linear combination equation 1 of a dependent variable Z1(f) and two independent variables H(f) and A(f) based on the frequency response coefficient R1(f) of the magnetoelectric heterostructure (101) to the magnetic signal and the frequency response coefficient R3(f) of the sound signal in a biased magnetic field state; and to establish a weighted linear combination equation 2 of a dependent variable Z2(f) and two independent variables H(f) and A(f) based on the frequency response coefficient R2(f) of the magnetoelectric heterostructure (101) to the magnetic signal and the frequency response coefficient R3(f) of the sound signal in a non-biased magnetic field state;

[0024] A frequency domain equation decoupling module (304) is used to decouple H(f) and A(f) by combining two equations and using elimination method;

[0025] A magnetic signal inverse Fourier transform module (305), used for performing inverse Fourier transform on the frequency domain of the magnetic signal H(f) to obtain an independent magnetic signal H(t);

[0026] The inverse Fourier transform module (306) of the sound signal is used to perform the inverse Fourier transform on the sound signal in the frequency domain A(f) to obtain the independent sound signal A(t). Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the specific structure of the device of the present invention.

[0028] In the figure: 101 - magnetoelectric heterostructure, 102 - solenoid, 103 - control circuit (MCU), 104 - signal source, 105 - electric amplifier, 106 - acquisition card.

[0029] Figure 2 It is a schematic diagram of the magnetoelectric heterostructure used in the present invention.

[0030] In the figure: 201 - amorphous soft magnetic alloy, 202 - polyimide film, 203 - lead zirconate titanate-based piezoelectric ceramic material, 204 - silver electrode, 205 - copper foil, 206 - wire.

[0031] Figure 3 It is a data processing flow chart inside the acquisition card (106) of the present invention.

[0032] In the figure: 301 - odd-even grouping module, 302 - Fourier transform module, 303 - frequency domain equation establishment module, 304 - frequency domain decoupling module, 305 - inverse Fourier transform module of magnetic signal, 306 - inverse Fourier transform module of sound signal.

[0033] Figure 4A It is the response degree R1(f) of the magnetoelectric heterostructure to the magnetic signal when the DC bias magnetic field is 6 Oe.

[0034] Figure 4B It is the response degree R2(f) of the magnetoelectric heterostructure to the magnetic signal when the DC bias magnetic field is 0 Oe.

[0035] Figure 4C It is the response degree R3(f) of the magnetoelectric heterostructure to the sound signal.

[0036] Figure 5A Original magnetic signal to be measured, sound signal, sound-magnetic coexistence signal.

[0037] Figure 5B It is the spectrum of the acquired electrical signal when the DC bias magnetic field is 6 Oe.

[0038] Figure 5C It is the spectrum of the acquired electrical signal when the DC bias magnetic field is 0 Oe.

[0039] Figure 5D It is the frequency domain diagram and time domain diagram of the magnetic signal to be measured obtained by demodulation.

[0040] Figure 5E The frequency-domain and time-domain diagrams of the sound signal to be measured obtained by demodulation. Specific implementation manner

[0041] In order to describe the present invention more specifically, the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0042] Figure 1 This is a schematic structural diagram of a specific acoustic-magnetic coexistence sensing and demodulation device based on a magnetoelectric heterostructure of the present invention. The entire device includes: a magnetoelectric heterostructure (101), a solenoid (102), a control circuit (MCU) (103), a signal source (104), an electrical amplifier (105), and a data acquisition card (106).

[0043] Figure 2 This is a composition diagram of the magnetoelectric heterostructure of an acoustic-magnetic coexistence sensing device based on a magnetoelectric heterostructure of the present invention. As Figure 2 shown, it includes: an amorphous soft magnetic alloy (201), a polyimide film (202), a piezoelectric ceramic lead zirconate titanate-based material (203), a silver electrode (204), a copper foil (205), and a wire (206).

[0044] In this embodiment, the magnetoelectric heterostructure (101) is a layered structure formed by bonding two upper and lower amorphous soft magnetic alloys (201) and seven piezoelectric ceramic lead zirconate titanate-based materials (203) with equal volume in the middle with epoxy glue. The amorphous soft magnetic alloy (201) is magnetized along the length direction, and the piezoelectric ceramic lead zirconate titanate-based material (203) is polarized along the thickness direction and arranged alternately in a form with opposite adjacent polarization directions. The polyimide film (202) is used between the amorphous soft magnetic alloy (201) and the piezoelectric ceramic lead zirconate titanate-based material (203) to achieve electrical insulation. The surface electrode of PZT-5H (203) is a silver electrode (204), and the copper foil (205) and the wire (206) are fixed on the electrode by conductive silver glue to respectively achieve electrical series connection of the electrodes and electrical signal transmission.

[0045] In this embodiment, the control circuit (MCU) (103) controls the signal source (104) to output a square wave signal with a frequency of f, which acts on the solenoid (102), and the expression of the generated modulation bias magnetic field is:

[0046] B(t) = B1·sgn(sin(2πf·t))

[0047] That is, the DC bias magnetic field of the magnetoelectric heterostructure (101) is B1 in the first half cycle and 0 in the second half cycle. Based on the characteristics of the magnetoelectric heterostructure (101), changing the DC bias magnetic field will change its responsiveness to magnetic signals, but will not change its responsiveness to sound signals. Denote the frequency response coefficient of the magnetoelectric heterostructure (101) to magnetic signals in the first half cycle as R1(f), and the frequency response coefficient of the magnetoelectric heterostructure (101) to magnetic signals in the second half cycle as R2(f). The frequency response coefficients to sound signals in both states are R3(f). The output electrical signals of the magnetoelectric heterostructure (101) under the two bias magnetic fields are input to the electrical amplifier (105) for amplification and collected by the acquisition card (106) to be converted into digital signals.

[0048] In this embodiment, the acoustic-magnetic fusion coexisting signal propagates along the length direction of the magnetoelectric heterostructure (101). Therefore, the magnetoelectric heterostructure (101) generates strain along the length direction. Also, because the magnetoelectric heterostructure (101) is a symmetric layered structure, it has a length resonance frequency point. When the sensing signal frequency approaches this resonance frequency, the amplitude and phase of the responsiveness of the magnetoelectric heterostructure (101) to the acoustic-magnetic fusion signal will change significantly; while when it is far from the resonance frequency point, the change in responsiveness is extremely small.

[0049] In this embodiment, the control circuit (MCU) (103) controls the sampling frequency of the acquisition card (106) to be 2f and adjusts the sampling delay so that the sampling points are located at the midpoint moments of the high and low levels of the modulated magnetic field square wave signal. That is, within one period of the modulated bias magnetic field, the acquisition card (106) performs two signal samplings, and the magnetoelectric heterostructure (101) is in different bias magnetic fields at the two sampling moments. Assuming sampling starts from the first period at the 0 moment of the square wave, the sampling signal can be expressed as

[0050]

[0051] Let the magnetic signal to be measured be \(H(t)\), the sound signal to be measured be \(A(t)\), the frequency domain of the magnetic signal to be measured be \(H(f)\), and the frequency domain of the sound signal to be measured be \(A(f)\). The sampled electrical signal data is grouped into odd and even groups. The odd-group signal \(Z1(N)\) is the electrical signal output by the electrical amplifier (105) when the frequency response coefficient of the magnetoelectric heterostructure (101) to the magnetic signal is \(R1(f)\), and the even-group signal \(Z2(N)\) is the electrical signal output by the electrical amplifier (105) when the frequency response coefficient of the magnetoelectric heterostructure (101) to the magnetic signal is \(R2(f)\). Fourier transforms are performed on \(Z1(N)\) and \(Z1(N)\) to obtain their frequency domain signals \(Z1(f)\) and \(Z2(f)\). Based on the frequency response coefficients of the magnetoelectric heterostructure (101) to the magnetic signal and the sound signal in the presence and absence of a bias magnetic field, a weighted linear combination equation of \(Z1(f)\), \(Z2(f)\) with the magnetic signal frequency domain \(H(f)\) and the sound signal frequency domain \(A(f)\) is established. Since the output electrical signal is the result of the common sensing of the sound-magnetic fusion signal, we have:

[0052]

[0053] Using the elimination method to solve, we can obtain that \(H(f)\) and \(A(f)\) are respectively:

[0054]

[0055] Performing inverse Fourier transforms on \(H(f)\) and \(A(f)\) can obtain the magnetic signal \(H(t)\) and the sound signal \(A(t)\), and thus the demodulation process of the magnetic signal and the sound signal is completed.

[0056] In this embodiment, the DC bias magnetic field in the first half cycle is set to 6 Oe, and the DC bias magnetic field in the second half cycle is set to 0 Oe. At this time, the response degrees \(R1(f)\) and \(R2(f)\) of the magnetoelectric heterostructure (101) to the magnetic signal, and the response degree \(R3(f)\) to the sound signal are as Figure 4A 、 Figure 4B 、 Figure 4C shown. Assume that the expressions of the magnetic signal \(H(t)\) and the sound signal \(A(t)\) are respectively:

[0057] H(t) = H0·cos(2π·300·t) + H1·cos(2π·7000·t)

[0058] A(t) = A0·cos(2π·800·t) + A1·cos(2π·7000·t)

[0059] where, the magnetic signal amplitudes are \(H0 = 2 Oe\), \(H1 = 1 Oe\); the sound signal amplitudes are \(A0 = 2 MPa\), \(A1 = 1 MPa\). Denote the sound-magnetic fusion signal \(C(t)\), that is, \(C(t)=H(t)+A(t)\), Figure 5A The above figure is the magnetic signal to be measured, Figure 5AThe middle picture shows the sound signal to be tested. Figure 5A The figure below shows the acoustic-magnetic fusion signal to be measured. The expressions of the magnetic signal frequency domain H(f) and the sound signal frequency domain A(f) are:

[0060] H(f)=2·δ(f-300)+δ(f-7000)

[0061] A(f)=2·δ(f-800)+δ(f-7000)

[0062] Figure 5B is the spectrum of the collected electrical signal Z1(f) when the DC bias magnetic field is 6Oe, Figure 5C is the collected electrical signal spectrum Z2(f) when the DC bias magnetic field is 0Oe, then the expressions of the two are:

[0063]

[0064] The two frequency domain equations are combined and the elimination method is used to decouple the acoustic and magnetic signals. Figure 5D The upper figure is the frequency domain diagram of the independent magnetic signal obtained by demodulation, and the lower figure is the time domain diagram of the magnetic signal obtained by demodulation; Figure 5E The upper figure is a frequency domain diagram of the demodulated independent sound signal, and the lower figure is a time domain diagram of the demodulated sound signal. The demodulated magnetic signal and sound signal are the same as the magnetic signal and sound signal to be measured. It can be seen that the present invention realizes the demodulation processing of the acoustic-magnetic fusion coexistence signal.

[0065] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made to the present invention by those skilled in the art based on the disclosure of the present invention should be within the scope of protection of the present invention.

Claims

1. A method and device for sensing and demodulating acoustic-magnetic coexistence signals based on magnetoelectric heterostructures, characterized in that: It includes a sensing module and a control module (MCU); wherein the sensing module is used to sense the acoustic-magnetic coexistence signal and output an electrical signal, and the control module (MCU) is used to generate a modulated square wave level signal and control the sampling frequency and delay of the signal, and realize the decoupling processing of the acoustic-magnetic coexistence signal at the same time; this scheme utilizes the characteristics of the magnetoelectric heterostructure that the response degree of the magnetic signal changes under different DC bias magnetic fields while the response degree of the sound signal remains consistent, combined with the acoustic-magnetic fusion signal decoupling algorithm, to realize the independent sensing and demodulation of the sound signal and the magnetic signal in the acoustic-magnetic coexistence signal.

2. The sensor demodulation device according to claim 1, characterized in that: The sensing module comprises a magnetoelectric heterostructure (101) and a solenoid (102), wherein: A magnetoelectric heterostructure (101) for responding to an acoustic-magnetic fusion signal and outputting an electrical signal; The solenoid (102) is used to provide a DC bias magnetic field.

3. The sensor demodulation device according to claim 2, characterized in that: The magnetoelectric heterostructure (101) is formed by bonding two upper and lower layers of amorphous soft magnetic alloy (201) and seven pieces of piezoelectric ceramic lead zirconate titanate-based materials (203) in the middle by epoxy adhesive into a layered structure.

4. The sensor demodulation device according to claim 3, characterized in that: The amorphous soft magnetic alloy (201) is magnetized along the length direction, and the piezoelectric ceramic lead zirconate titanate-based material (203) is polarized along the thickness direction, and the materials are alternately arranged in a form in which adjacent polarization directions are opposite.

5. The sensor demodulation device according to claim 3, characterized in that: A polyimide film (202) is used to achieve electrical insulation between the amorphous soft magnetic alloy (201) and the piezoelectric ceramic lead zirconate titanate-based material (203); the surface electrode of the piezoelectric ceramic lead zirconate titanate-based material (203) is a silver electrode (204); the copper foil (205) and the wire (206) are fixed on the electrode by conductive silver glue, respectively achieving electrical series connection of the electrodes and electrical signal transmission.

6. The sensor demodulation device according to claim 1, characterized in that: The control module (MCU) comprises a control circuit (MCU) (103), a signal source (104), an electric amplifier (105), and a collection card (106), wherein: A control circuit (MCU) (103) is used to control the output level of the signal source (104) and the sampling frequency and delay of the acquisition card (106); A signal source (104) for generating a modulated square wave signal to control the change of a DC bias magnetic field; An electrical amplifier (105) for amplifying the electrical signal output by the magnetoelectric heterostructure (101); The acquisition card (106) is used to convert the electrical signal into a digital signal to perform acoustic-magnetic coexistence signal demodulation.

7. The sensor demodulation device according to claim 6, characterized in that: The frequency of the square wave signal is more than ten times greater than the highest frequency of the sensing signal.

8. The sensor demodulation device according to claim 6, characterized in that: The sampling frequency is twice the frequency of the square wave signal, and the sampling delay is the time position when the sampling point is located at the middle point of the high and low levels of the modulated square wave signal.

9. The sensor demodulation device according to claim 6, characterized in that: For sensing and demodulating the magnetic signal to be measured as H(t) and the sound signal as A(t) (the frequency domain of the magnetic signal is H(f), and the frequency domain of the sound signal is A(f)), the acquisition card (106) comprises the following digital signal processing modules: An odd-even grouping module (301) is used to perform odd-even grouping on the collected electrical signals to obtain odd-group signals Z1(N) and even-group signals Z2(N), wherein the odd-group signals Z1(N) are output electrical signals of the electrical amplifier (105) when the magnetoelectric heterostructure (101) has a direct current bias magnetic field, and the even-group signals Z1(N) are output electrical signals of the electrical amplifier (105) when the magnetoelectric heterostructure (101) has no direct current bias magnetic field; A Fourier transform module (302), used for performing Fourier transform on Z1(N) and Z2(N) to obtain frequency spectra Z1(f) and Z2(f); A frequency domain equation establishment module (303) is used to establish a weighted linear combination equation 1 of a dependent variable Z1(f) and two independent variables H(f) and A(f) based on the frequency response coefficient R1(f) of the magnetoelectric heterostructure (101) to the magnetic signal and the frequency response coefficient R3(f) of the sound signal in a biased magnetic field state; and to establish a weighted linear combination equation 2 of a dependent variable Z2(f) and two independent variables H(f) and A(f) based on the frequency response coefficient R2(f) of the magnetoelectric heterostructure (101) to the magnetic signal and the frequency response coefficient R3(f) of the sound signal in a non-biased magnetic field state; A frequency domain decoupling module (304) is used to decouple H(f) and A(f) by combining two equations and using elimination method; A magnetic signal inverse Fourier transform module (305), used for performing inverse Fourier transform on the frequency domain of the magnetic signal H(f) to obtain an independent magnetic signal H(t); The sound signal inverse Fourier transform module (306) is used to perform inverse Fourier transform on the sound signal frequency domain A(f) to obtain an independent sound signal A(t).

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