A long-wave communication system based on vibration beam and method thereof

Abstract

The present invention discloses a long-wave communication system and method based on a vibrating beam. The system comprises: a signal generator configured to generate an excitation signal and vibrate according to the excitation signal to drive a radiation source device to vibrate; a radiation source device configured to generate a time-varying magnetic field; and a signal receiver configured to sense the time-varying magnetic field, generate an induced electromotive force, and perform data processing on the induced electromotive force to achieve communication. By analyzing the dynamic characteristics of a permanent magnet mechanical antenna, the present invention demonstrates the feasibility and effectiveness of using a small-sized mechanical antenna to excite low-frequency signals, thereby achieving low-frequency signal communication.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical antennas, and in particular to a long-wave communication system based on a vibration beam and a method thereof. Background Art

[0002] In the traditional wireless communication field, long-wave communication requires matching large-size signal transmitting antennas, which restricts its application on small and medium-sized platforms.

[0003] Low-frequency electromagnetic waves have longer wavelengths, boasting long propagation distances, strong penetration, and slow attenuation. They are widely used in underwater communications, navigation, and positioning. Traditional antenna size depends on the wavelength of the electromagnetic wave, making low-frequency antennas bulky and complex.

[0004] Currently, mechanical antennas can be categorized into three types based on their electromagnetic wave excitation method: electret, permanent magnet, and piezoelectric. The radiation intensity of electret mechanical antennas is closely related to charge density, making it difficult to increase the charge density on the electret surface. Piezoelectric mechanical antennas are limited by the size of the piezoelectric material and have a limited radiation area. Permanent magnet mechanical antennas, however, leverage the high magnetic remanence of neodymium iron boron permanent magnets to achieve higher radiation intensity in the near field than the other two options.

[0005] Because frequency modulation is less affected by external noise, it is the best choice for mechanical antenna signal modulation. The cantilever beam has a simple structure and complex modes. The multimodal vibration characteristics of the cantilever beam structure can be combined with a permanent magnet to generate complex electromagnetic waves. Summary of the Invention

[0006] The purpose of the present invention is to provide a long-wave communication system and method based on a vibrating beam. By analyzing the dynamic characteristics of a permanent magnet mechanical antenna, the system can excite low-frequency signals using a small-sized mechanical antenna, thereby realizing the feasibility and effectiveness of low-frequency signal communication.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] The present invention provides a long-wave communication system based on a vibration beam, the long-wave communication system based on a vibration beam comprising:

[0009] a signal generating device, the signal generating device being configured to generate an excitation signal and vibrate according to the excitation signal to drive the radiation source device to vibrate;

[0010] a radiation source device, the radiation source device being used to generate a time-varying magnetic field;

[0011] a signal receiving device configured to sense the time-varying magnetic field, generate an induced electromotive force, and perform data processing on the induced electromotive force to achieve communication;

[0012] The radiation source device is constructed as a three-degree-of-freedom folding beam structure and includes:

[0013] A rigid connector, the rigid connector being vertically arranged and having a first connecting end and a second connecting end opposite to each other along a height extension direction thereof,

[0014] a first beam portion, the first beam portion including a first beam body, the first beam body being arranged perpendicular to the height extension direction of the rigid connector and including a fixed end and a folded portion, the fixed end being fixedly arranged, and the fixed surface of the folded portion being used to fix the first connecting end;

[0015] a second beam portion, the second beam portion being arranged parallel to the first beam portion and comprising a third connecting end and a free end, the third connecting end being fixed to the second connecting end, and the free end being arranged close to the fixed end;

[0016] The second beam portion includes a plurality of beam bodies arranged in parallel, and a permanent magnet is arranged at the free end of each beam body.

[0017] Optionally, a ceramic piezoelectric sheet is further provided on the first beam, and one end of the ceramic piezoelectric sheet is flush with the fixed end.

[0018] Optionally, the second beam portion includes a second beam body and a third beam body arranged in parallel, a first permanent magnet is arranged on the free end of the second beam body, and a second permanent magnet is arranged on the free end of the third beam body.

[0019] Optionally, the signal generating device includes a function generator, a power amplifier and a piezoelectric sensor connected in sequence, wherein the function generator is used to generate the voltage and frequency of the excitation signal;

[0020] The power amplifier is used to amplify the voltage of the excitation signal to obtain an excitation voltage;

[0021] The piezoelectric sensor is used to receive the excitation voltage and generate vibration according to the excitation voltage to drive the radiation source device to vibrate.

[0022] Optionally, the signal receiving device includes a coil, an oscilloscope and a data processing module, and the coil serves as a signal receiving end to sense the time-varying magnetic field generated by the vibration of the permanent magnet to generate an induced electromotive force;

[0023] The oscilloscope is used to receive and store the induced electromotive force, and send the induced electromotive force to the data processing module;

[0024] The data processing module is used to encode and decode the induced electromotive force to achieve communication.

[0025] The present invention also provides a long-wave communication method based on a vibration beam, the long-wave communication method based on a vibration beam is based on the above-mentioned long-wave communication system based on a vibration beam, and the long-wave communication method based on a vibration beam includes:

[0026] S1: Control signal generating device to generate excitation signal;

[0027] S2: amplifying the voltage of the excitation signal to obtain an excitation voltage;

[0028] S3: using a piezoelectric sensor to receive the excitation voltage and generate vibration according to the excitation voltage to drive the radiation source device to vibrate;

[0029] S4: controlling the radiation source device to generate a time-varying magnetic field according to the vibration;

[0030] S5: generating an induced electromotive force according to the time-varying magnetic field;

[0031] S6: Performing data processing on the induced electromotive force to achieve communication.

[0032] Optionally, step S5 includes:

[0033] S51: Determine the magnetic field strength based on the vibration displacement;

[0034] S52: Obtaining an induced electromotive force according to the magnetic field strength, the number of turns of the coil and the cross-sectional area thereof.

[0035] Alternatively, the vibration displacement in step S51 is obtained by:

[0036] A1: Based on the three-degree-of-freedom reentrant beam structure, construct a mass matrix and a stiffness matrix of the three-degree-of-freedom reentrant beam structure;

[0037] A2: Determine the vibration motion equation of the three-degree-of-freedom reentrant beam structure based on the mass matrix and the stiffness matrix;

[0038] A3: Calculate the equivalent concentrated force of the ceramic piezoelectric plate on the three-degree-of-freedom folded-back beam structure under the current excitation voltage;

[0039] A4: According to the vibration motion equation and the equivalent concentrated force, the vibration displacement of the rigid connector and the vibration displacement of the permanent magnet under the current excitation voltage are obtained;

[0040] In step A2, the vibration motion equation of the three-degree-of-freedom folding beam structure is:

[0041]

[0042] Where m1 represents the mass of the rigid connector, m2 represents the mass of the first permanent magnet, m3 represents the mass of the second permanent magnet, and c ij Represents the relevant components in the damping matrix and the damping matrix is ​​C = αM + βK, M represents the mass matrix of the three-degree-of-freedom folded-back beam structure, K represents the stiffness matrix of the three-degree-of-freedom folded-back beam structure, α and β are the mass damping coefficient and the stiffness damping coefficient respectively, y1, y2 and y3 represent the vertical displacements of the rigid connector, the first permanent magnet and the second permanent magnet respectively, and are the vertical velocities of the connecting member, the first permanent magnet, and the second permanent magnet, respectively. and denote the accelerations of the connecting member, the first permanent magnet, and the second permanent magnet in the vertical direction, respectively; F(t) denotes the equivalent concentrated force of the ceramic piezoelectric plate on the three-degree-of-freedom foldback beam structure;

[0043] In step A3, the equivalent concentrated force F(t) of the ceramic piezoelectric sheet on the three-degree-of-freedom folded-back beam structure is:

[0044]

[0045] Where M represents the strain generated by the ceramic piezoelectric sheet acting on the first beam, so that the bending moment generated by the first beam is ε represents the current excitation voltage u(t) of the ceramic piezoelectric piece. i sin(2πf i t) and the strain generated by the excitation Δl is the deformation of the ceramic piezoelectric piece; l is the length of the ceramic piezoelectric piece, h p is the thickness of the ceramic piezoelectric sheet, d 31 A represents the piezoelectric constant of the ceramic piezoelectric piece. i represents the excitation voltage amplitude, π is the circumference of a circle, and f i represents the frequency of the excitation voltage, t represents the excitation time, E1 represents the elastic modulus of the first beam, I1 represents the moment of inertia of the first beam, h1 represents the thickness of the first beam, and L1 represents the length of the first beam.

[0046] Optionally, in step S51, the magnetic field strength B is:

[0047]

[0048] Where μ0 represents the magnetic permeability of vacuum, m represents the magnetic dipole moment, b represents the ordinate of any point P(a, b) in space, y(t) represents the vibration displacement, a represents the abscissa of any point P(a, b) in space, and π represents the circumference of a circle.

[0049] In step S52, the induced electromotive force U is:

[0050]

[0051] Among them, N a represents the number of turns of the coil, ψ represents the magnetic flux through the coil and ψ=BA a , A a represents the cross-sectional area of ​​the coil, B represents the magnetic field strength and μ0 represents the magnetic permeability of vacuum, m represents the magnetic dipole moment, b represents the y-axis coordinate of point P, y(t) represents the vibration displacement, a represents the x-axis coordinate of point P, π represents pi, and t represents the excitation time.

[0052] Optionally, step S6 includes:

[0053] S61: taking the maximum value of the induced electromotive force as the signal strength;

[0054] S62: Determine whether the signal strength of each permanent magnet is equal to the signal strength of the rigid connector. If so, proceed to step S63; otherwise, adjust the current excitation voltage value and return to step S1.

[0055] S63: Encode the frequency and time information of the excitation signal to obtain encoded data;

[0056] S64: Decode the encoded information using the SLs signal analysis method to achieve communication.

[0057] The present invention has the following beneficial effects:

[0058] 1) Based on the inverse piezoelectric effect, the radiation theory of vibrating permanent magnet mechanical antennas, and the principle of low-frequency electromagnetic wave communication, the present invention proposes a three-degree-of-freedom folded-back beam structure, thereby deriving the relationship between the first three natural frequencies of the folded-back beam structure and the magnetic field strength of the vibrating permanent magnet;

[0059] 2) The present invention utilizes the relationship between the vibration displacement of the permanent magnet and the induced electromotive force at the receiving end to derive the relationship between the excitation voltages of excitation signals of different frequencies;

[0060] 3) The present invention combines the inverse piezoelectric effect, electromagnetism and vibration dynamics to achieve the excitation of low-frequency signals using a small-sized mechanical antenna, thereby realizing the feasibility and effectiveness of low-frequency signal communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Schematic diagram of the structure of the long-wave communication system based on the vibration beam of the present invention;

[0062] Figure 2 Schematic diagram of the structure of the three-degree-of-freedom folding beam structure of the present invention;

[0063] Figure 3 This is a flow chart of the long-wave communication method based on a vibration beam of the present invention;

[0064] Figure 4 is the displacement of the rigid connector, the first permanent magnet, and the second permanent magnet at different excitation frequencies;

[0065] Figure 5 Flowchart for signal strength calculation;

[0066] Figure 6 This is a schematic diagram of the signal processing results of the theoretical results;

[0067] Figure 7 Schematic diagram of the signal processing results of the excitation voltage optimization theory.

[0068] Description of Reference Numerals

[0069] 1-rigid connecting member; 11-first connecting end; 12-second connecting end; 2-first beam, 21-fixed end; 22-return portion; 23-ceramic piezoelectric plate; 31-third connecting end; 32-free end; 33-second beam; 34-third beam; 35-first permanent magnet; 36-second permanent magnet. DETAILED DESCRIPTION

[0070] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0071] The present invention provides a long wave communication system based on a vibration beam, referring to Figure 1 As shown, the long-wave communication system based on the vibration beam includes:

[0072] a signal generating device, the signal generating device being configured to generate an excitation signal and vibrate according to the excitation signal to drive the radiation source device to vibrate;

[0073] a radiation source device, the radiation source device being used to generate a time-varying magnetic field;

[0074] a signal receiving device configured to sense the time-varying magnetic field, generate an induced electromotive force, and perform data processing on the induced electromotive force to achieve communication;

[0075] The radiation source device is constructed as a three-degree-of-freedom folding beam structure and refers to Figure 2 As shown ((a) front view, (b) top view), the three-degree-of-freedom foldback beam structure includes:

[0076] A rigid connector 1 is vertically arranged and has a first connecting end 11 and a second connecting end 12 arranged opposite to each other along its height extension direction.

[0077] a first beam portion, the first beam portion including a first beam body 2, the first beam body 2 being arranged perpendicular to the height extension direction of the rigid connector 1, and including a fixed end 21 and a folded portion 22, the fixed end 21 being fixedly arranged, and the fixed surface of the folded portion 22 being used to fix the first connecting end 11;

[0078] a second beam portion, the second beam portion being arranged parallel to the first beam portion and comprising a third connecting end 31 and a free end 32, the third connecting end 31 being fixed to the second connecting end 12, and the free end 32 being arranged close to the fixed end 21;

[0079] The second beam portion includes a plurality of beam bodies arranged in parallel, and a permanent magnet is arranged at the free end of each beam body.

[0080] In the present invention, the second beam portion includes a second beam body 33 and a third beam body 34 arranged in parallel. A first permanent magnet 35 is provided on the free end 32 of the second beam body 33, and a second permanent magnet 36 is provided on the free end 32 of the third beam body 34. Of course, those skilled in the art may, in combination with the present invention and actual conditions, specifically set the number of beam bodies in the second beam portion, and the present invention does not impose any limitation thereto.

[0081] Optionally, a ceramic piezoelectric sheet 23 is further provided on the first beam 2 , and one end of the ceramic piezoelectric sheet 23 is flush with the fixed end 21 .

[0082] The three-degree-of-freedom folded-back beam structure of the present invention utilizes the inverse piezoelectric effect of the ceramic piezoelectric plate 23. An amplified alternating voltage is applied to the ceramic piezoelectric plate 23, causing it to deform. This in turn drives the first beam 2 to vibrate, and the first and second permanent magnets 35, 36 also vibrate along with the second and third beams 33, 34. Ultimately, the receiving coil receives the superimposed magnetic field generated by the vibrations of the first and second permanent magnets 35, 36, enabling communication.

[0083] Optionally, the signal generating device includes a function generator, a power amplifier and a piezoelectric sensor connected in sequence, wherein the function generator is used to generate the voltage and frequency of the excitation signal;

[0084] The power amplifier is used to amplify the voltage of the excitation signal to obtain an excitation voltage;

[0085] The piezoelectric sensor is used to receive the excitation voltage and generate vibration according to the excitation voltage to drive the radiation source device to vibrate.

[0086] Optionally, the signal receiving device includes a coil, an oscilloscope and a data processing module, and the coil serves as a signal receiving end to sense the time-varying magnetic field generated by the vibration of the permanent magnet to generate an induced electromotive force;

[0087] The oscilloscope is used to receive and store the induced electromotive force, and send the induced electromotive force to the data processing module;

[0088] The data processing module is used to encode and decode the induced electromotive force to achieve communication.

[0089] The present invention also provides a long wave communication method based on a vibration beam, referring to Figure 3 As shown, the long-wave communication method based on a vibration beam is based on the above-mentioned long-wave communication system based on a vibration beam, and the long-wave communication method based on a vibration beam includes:

[0090] S1: Control signal generating device to generate excitation signal;

[0091] S2: amplifying the voltage of the excitation signal to obtain an excitation voltage;

[0092] S3: using a piezoelectric sensor to receive the excitation voltage and generate vibration according to the excitation voltage to drive the radiation source device to vibrate;

[0093] Specifically, the voltage and frequency of the excitation signal are generated by a function generator, and then the voltage of the excitation signal is amplified by a power amplifier. After that, the piezoelectric sensor vibrates after receiving the excitation voltage, thereby driving the radiation source (that is, the three-degree-of-freedom folding beam of the present invention) to vibrate.

[0094] S4: controlling the radiation source device to generate a time-varying magnetic field according to the vibration;

[0095] Since the radiation source device contains a permanent magnet, during the vibration process, the vibration of the permanent magnet is affected by time and voltage changes, thereby generating a time-varying magnetic field.

[0096] S5: generating an induced electromotive force according to the time-varying magnetic field;

[0097] Optionally, step S5 includes:

[0098] S51: Determine the magnetic field strength based on the vibration displacement;

[0099] The magnetic field strength B is:

[0100]

[0101] Among them, μ0 represents the magnetic permeability of vacuum, m represents the magnetic dipole moment, b represents the vertical coordinate of any point P(a,b) in space, y(t) represents the vibration displacement, a represents the horizontal coordinate of any point P(a,b) in space, and π represents pi.

[0102] The vibration displacement in step S51 is obtained by:

[0103] A1: Based on the three-degree-of-freedom reentrant beam structure, construct a mass matrix and a stiffness matrix of the three-degree-of-freedom reentrant beam structure;

[0104] A2: Determine the vibration motion equation of the three-degree-of-freedom reentrant beam structure based on the mass matrix and the stiffness matrix;

[0105] In the present invention, in order to facilitate the analysis of the vibration frequency response of the three-degree-of-freedom folded-back beam structure, the mass of the beam and the ceramic piezoelectric plate 23 is ignored, and the mass matrix M of the three-degree-of-freedom folded-back beam structure is:

[0106]

[0107] Wherein, m1 represents the mass of the rigid connection member 1 , m2 represents the mass of the first permanent magnet 35 , and m3 represents the mass of the second permanent magnet 36 .

[0108] Similarly, according to the standard stiffness influence coefficient method in material mechanics, the stiffness matrix K of the three-degree-of-freedom reentrant beam structure is obtained as follows:

[0109]

[0110] Among them, k ij represents the relevant components in the stiffness matrix and A1, A2, A3, B1, B2, B3, C1, C2, C3 and D are intermediate parameters and E1, E2 and E3 are the elastic moduli of the first beam 2, the second beam 33 and the third beam 34 respectively; I1, I2 and I3 are the moments of inertia of the first beam 2, the second beam 33 and the third beam 34 respectively; L1, L2 and L3 are the lengths of the first beam 2, the second beam 33 and the third beam 34 respectively.

[0111] The parameters of the components of the three-degree-of-freedom folding beam structure of the present invention are listed in Table 1.

[0112] Table 1 Parameters related to the folded beam structure

[0113]

[0114] In addition, the present invention also solves the three-degree-of-freedom system equation K=ω 2The eigenvalues ​​of M are used to obtain its natural frequency and vibration mode.

[0115] Table 2 shows the first three vibration mode vectors, and the theoretical values ​​of the first three natural frequencies are f1 = 11.5 Hz, f2 = 12.6 Hz, and f3 = 22.0 Hz, respectively. Table 2 shows that in the first vibration mode, the amplitudes of the first permanent magnet 35 and the second permanent magnet 36 are identical and significantly larger than that of the rigid connector 1. In the second vibration mode, the amplitude of the rigid connector 1 is almost zero, while the amplitudes of the first permanent magnet 35 and the second permanent magnet 36 are equal, with a phase difference of 180°. In the third vibration mode, the amplitudes of the first permanent magnet 35 and the second permanent magnet 36 are identical and smaller than that of the rigid connector 1.

[0116] Table 2. Vibration shape vectors of the structure

[0117]

[0118] S2: Determine a vibration motion equation of a three-degree-of-freedom reentrant beam structure according to the mass matrix and the stiffness matrix;

[0119] The vibration motion equation of the three-degree-of-freedom reentrant beam structure is:

[0120]

[0121] Where m1 represents the mass of the rigid connector, m2 represents the mass of the first permanent magnet, m3 represents the mass of the second permanent magnet, and c ij Represents the relevant components in the damping matrix and the damping matrix is ​​C = αM + βK, M represents the mass matrix of the three-degree-of-freedom folded-back beam structure, K represents the stiffness matrix of the three-degree-of-freedom folded-back beam structure, α and β are the mass damping coefficient and the stiffness damping coefficient respectively, y1, y2 and y3 represent the vertical displacements of the rigid connector, the first permanent magnet and the second permanent magnet respectively, and are the vertical velocities of the connecting member, the first permanent magnet, and the second permanent magnet, respectively. and They represent the accelerations of the connecting member, the first permanent magnet and the second permanent magnet in the vertical direction respectively, and F(t) represents the equivalent concentrated force of the ceramic piezoelectric piece on the three-degree-of-freedom foldback beam structure.

[0122] A3: Calculate the equivalent concentrated force of the ceramic piezoelectric plate on the three-degree-of-freedom foldback beam structure under the current excitation voltage;

[0123] The equivalent concentrated force F(t) of the ceramic piezoelectric plate on the three-degree-of-freedom foldback beam structure is:

[0124]

[0125] Where M represents the strain generated by the ceramic piezoelectric sheet acting on the first beam, so that the bending moment generated by the first beam is ε represents the current excitation voltage u(t) of the ceramic piezoelectric piece. i sin(2πf i t) and the strain generated by the excitation Δl is the deformation of the ceramic piezoelectric piece; l is the length of the ceramic piezoelectric piece, h p is the thickness of the ceramic piezoelectric sheet, d 31 A represents the piezoelectric constant of the ceramic piezoelectric piece. i represents the excitation voltage amplitude, π is the circumference of a circle, and f i represents the frequency of the excitation voltage, t represents the excitation time, E1 represents the elastic modulus of the first beam, I1 represents the moment of inertia of the first beam, h1 represents the thickness of the first beam, and L1 represents the length of the first beam.

[0126] A4: According to the vibration motion equation and the equivalent concentrated force, the vibration displacement of the rigid connector and the vibration displacement of the permanent magnet under the current excitation voltage are obtained;

[0127] The fourth-order Runge-Kutta method has high calculation accuracy and accurate data, so this method and the equivalent concentrated force are used to solve the vibration motion equation. The calculation step size of each step in the calculation is 0.005. The frequency of the excitation signal of the ceramic piezoelectric piece 23 is the first three natural frequencies of the three-degree-of-freedom reentrant beam structure, which are 11.5Hz, 12.6Hz and 22.0Hz respectively. The corresponding excitation time is 0~40s, 40~80s and 80~120s respectively. The parameters used in the three-degree-of-freedom reentrant beam structure are shown in Table 3, and the displacements of the rigid connector 1, the first permanent magnet 35 and the second permanent magnet 36 are solved.

[0128] Table 3 Parameter values ​​used in displacement calculation

[0129]

[0130] The displacements y1, y2 and y3 of mass block 1, permanent magnets 2 and 3 are as follows: Figure 4 As shown. Figure 4 It can be seen from (a) 11.5 Hz, (b) 12.6 Hz and (c) 22.0 Hz that the displacements of the rigid connector 1, the first permanent magnet 35 and the second permanent magnet 36 at the first three natural frequencies are consistent with the vibration mode (see Table 2).

[0131] S52: Obtaining an induced electromotive force according to the magnetic field strength, the number of turns of the coil and the cross-sectional area thereof.

[0132] In the present invention, the low-frequency electromagnetic wave receiving device is a coil located on the y-axis. According to Faraday's law of electromagnetic induction, if the coil is in the time-varying magnetic field of the transmitting antenna, the coil will generate an induced electromotive force of the same frequency. Therefore, the induced electromotive force U is:

[0133]

[0134] Among them, N a represents the number of turns of the coil, ψ represents the magnetic flux through the coil and ψ=BA a , A a represents the cross-sectional area of ​​the coil, B represents the magnetic field strength and μ0 represents the magnetic permeability of vacuum, m represents the magnetic dipole moment, b represents the y-axis coordinate of point P, y(t) represents the vibration displacement, a represents the x-axis coordinate of point P, π represents pi, and t represents the excitation time.

[0135] S6: Performing data processing on the induced electromotive force to achieve communication.

[0136] Optionally, step S6 includes:

[0137] S61: taking the maximum value of the induced electromotive force as the signal strength;

[0138] S62: Determine whether the signal strength of each permanent magnet is equal to the signal strength of the rigid connector. If so, proceed to step S63; otherwise, adjust the current excitation voltage value and return to step S1.

[0139] S63: Encode the frequency and time information of the excitation signal to obtain encoded data;

[0140] S64: Decode the encoded information using the SLs signal analysis method to achieve communication.

[0141] In order to facilitate the decoding of the received signal by the receiving end, it is necessary to ensure that the strength of the received signal is consistent. Figure 6 In (b), the depth of the color represents the signal strength. It can be seen that the strength of the second-order and third-order frequency signals is significantly smaller than that of the first-order. In actual communication, the second-order and third-order frequency signals may be regarded as noise, which is not conducive to the decoding and processing of the received signal by the receiving end. According to the above scheme, it can be seen that the excitation voltage determines the size of the permanent magnet vibration displacement, and the strength of the induced electromotive force at the receiving end is related to the permanent magnet vibration displacement. Therefore, according to the vibration motion equation and formula The relationship between the intensity of the induced electromotive force at the receiving end and the excitation voltage can be determined.

[0142] It should be noted that adjusting the current excitation voltage value is actually adjusting the amplitude of the excitation voltage. Since u(t)=A isin(2πf i t), so when A i When adjusted, u(t) will also change accordingly. For details, refer to Figure 5 .

[0143] The present invention is analyzed based on the following theoretical foundations:

[0144] For vibrating mechanical antennas, frequency modulation of electromagnetic waves can be achieved by controlling the vibration frequency of the permanent magnet. The developed transmission protocol is shown in Table 4. It specifies that the first three vibration frequencies f1, f2, and f3 of the three-degree-of-freedom reentrant beam represent the "1" code, the "2" code, and the "3" code, respectively. The signal's time domain lengths, t1 = 10 seconds, t2 = 15 seconds, and t3 = 5 seconds, represent the "1" code and the "2" code, respectively. The absence of the excitation signal at time t3 indicates the end of an information code. An information code consists of three frequency-time combinations.

[0145] Table 4 Transmission protocol for mechanical antenna communication

[0146]

[0147] Assume the excitation voltage amplitude A1=A2=A3=200V, and substitute y2 and y3 into the formula The induced electromotive force caused by the time-varying magnetic field generated by the vibration of the permanent magnet can be obtained. When transmitting information, the frequency and time domain length of the excitation signal are shown in Table 5. It is stipulated that every 40 seconds is an information code, and there are 4 information codes in total. According to the transmission protocol in Table 4, it is converted into information codes ['112132', '211231', '123121', '312211'] for transmission. The coil receives the theoretical induced electromotive force generated by the first permanent magnet 35 and the second permanent magnet 36 as shown in Figure 6 (a) As shown in the induced electromotive force diagram, it can be seen that there are 4 obvious periodic signals.

[0148] Table 5 Frequency and time domain length of the excitation signal

[0149]

[0150] Based on the SLs signal analysis method, the signal received by the receiving coil is processed to obtain the time-frequency information of the signal, such as Figure 6 (b) Signal time-frequency diagram. Figure 6 The magnitude of the signal frequency and the time domain length of the signal in (b) can be used to derive four sets of information codes identical to those at the transmitter, theoretically verifying the feasibility of achieving low-frequency electromagnetic wave communication through mechanical antennas.

[0151] During the calculation process, the excitation voltage amplitude A1 corresponding to the first-order excitation frequency f1 is taken as 200V, and the corresponding signal strength P1 is 1.2×10 -4 ,according to Figure 5 The process is as follows, A2 = 525V, A3 = 612V, and the signal strength is as follows Figure 7 (a) As shown in the signal strength diagram, it can be seen from the figure that when the mechanical antenna structure vibrates stably, the signal strengths at frequencies f1, f2, and f3 are the same, which is approximately P = 1.2 × 10 -4 Then transmit the signal according to Table 5, process the received induced electromotive force using SLs signal, and obtain the signal time-frequency diagram, as shown in Figure 7 (b) The signal time-frequency diagram shows that Figure 6 Compared with (b), the colors of the signals corresponding to f1, f2, and f3 are consistent, indicating that the signal strengths are the same. Using the optimized excitation voltage value for communication is more conducive to the receiving end to decode the received information.

[0152] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A long wave communication system based on a vibrating beam, characterized in that: The long-wave communication system based on the vibration beam includes: a signal generating device, the signal generating device being configured to generate an excitation signal and vibrate according to the excitation signal to drive the radiation source device to vibrate; a radiation source device, the radiation source device being used to generate a time-varying magnetic field; a signal receiving device configured to sense the time-varying magnetic field, generate an induced electromotive force, and perform data processing on the induced electromotive force to achieve communication; The radiation source device is constructed as a three-degree-of-freedom folding beam structure and includes: A rigid connector, the rigid connector being vertically arranged and having a first connecting end and a second connecting end opposite to each other along a height extension direction thereof, a first beam portion, the first beam portion including a first beam body, the first beam body being arranged perpendicular to the height extension direction of the rigid connector and including a fixed end and a folded portion, the fixed end being fixedly arranged, and the fixed surface of the folded portion being used to fix the first connecting end; a second beam portion, the second beam portion being arranged parallel to the first beam portion and comprising a third connecting end and a free end, the third connecting end being fixed to the second connecting end, and the free end being arranged close to the fixed end; The second beam portion includes a plurality of beam bodies arranged in parallel, and a permanent magnet is provided at the free end of each beam body; Generating the induced electromotive force comprises: Determine the magnetic field strength based on the vibration displacement; Obtaining an induced electromotive force according to the magnetic field strength, the number of turns of the coil and its cross-sectional area; The vibration displacement is obtained by: A1: Based on the three-degree-of-freedom reentrant beam structure, construct a mass matrix and a stiffness matrix of the three-degree-of-freedom reentrant beam structure; A2: Determine the vibration motion equation of the three-degree-of-freedom reentrant beam structure based on the mass matrix and the stiffness matrix; A3: Calculate the equivalent concentrated force of the ceramic piezoelectric plate on the three-degree-of-freedom folded-back beam structure under the current excitation voltage; A4: According to the vibration motion equation and the equivalent concentrated force, the vibration displacement of the rigid connector and the vibration displacement of the permanent magnet under the current excitation voltage are obtained.

2. The long wave communication system based on a vibration beam according to claim 1, characterized in that: A ceramic piezoelectric sheet is further provided on the first beam, and one end of the ceramic piezoelectric sheet is flush with the fixed end.

3. The long wave communication system based on a vibration beam according to claim 1, characterized in that: The second beam portion includes a second beam body and a third beam body which are arranged in parallel. A first permanent magnet is arranged on the free end of the second beam body, and a second permanent magnet is arranged on the free end of the third beam body.

4. The long wave communication system based on a vibration beam according to claim 1, characterized in that: The signal generating device includes a function generator, a power amplifier and a piezoelectric sensor connected in sequence, wherein the function generator is used to generate the voltage and frequency of the excitation signal; The power amplifier is used to amplify the voltage of the excitation signal to obtain an excitation voltage; The piezoelectric sensor is used to receive the excitation voltage and generate vibration according to the excitation voltage to drive the radiation source device to vibrate.

5. The long wave communication system based on a vibration beam according to any one of claims 1 to 4, characterized in that: The signal receiving device includes a coil, an oscilloscope and a data processing module. The coil serves as a signal receiving end to sense the time-varying magnetic field generated by the vibration of the permanent magnet to generate an induced electromotive force. The oscilloscope is used to receive and store the induced electromotive force, and send the induced electromotive force to the data processing module; The data processing module is used to encode and decode the induced electromotive force to achieve communication.

6. A long wave communication method based on a vibrating beam, characterized in that: The long-wave communication method based on a vibration beam is based on the long-wave communication system based on a vibration beam according to any one of claims 1 to 5, and the long-wave communication method based on a vibration beam includes: S1: Control signal generating device to generate excitation signal; S2: amplifying the voltage of the excitation signal to obtain an excitation voltage; S3: using a piezoelectric sensor to receive the excitation voltage and generate vibration according to the excitation voltage to drive the radiation source device to vibrate; S4: controlling the radiation source device to generate a time-varying magnetic field according to the vibration; S5: generating an induced electromotive force according to the time-varying magnetic field; S6: Performing data processing on the induced electromotive force to achieve communication.

7. The long wave communication method based on a vibration beam according to claim 6, characterized in that: In A2, the vibration motion equation of the three-degree-of-freedom folding beam structure is: in, represents the mass of the rigid connector, represents the mass of the first permanent magnet, represents the mass of the second permanent magnet, represents the relevant components in the damping matrix, and the damping matrix is , represents the mass matrix of the three-degree-of-freedom folded-back beam structure, represents the stiffness matrix of the three-degree-of-freedom folded-back beam structure, are the mass damping coefficient and the stiffness damping coefficient, 、 and denote the vertical displacements of the rigid connector, the first permanent magnet, and the second permanent magnet, respectively. 、 and are the vertical velocities of the connecting member, the first permanent magnet, and the second permanent magnet, respectively. 、 and represent the vertical accelerations of the connecting member, the first permanent magnet, and the second permanent magnet, respectively, represents the equivalent concentrated force of the ceramic piezoelectric plate on the three-degree-of-freedom folding beam structure; In A3, the equivalent concentrated force of the ceramic piezoelectric sheet on the three-degree-of-freedom folding beam structure for: in, represents the strain generated by the ceramic piezoelectric sheet acting on the first beam, causing the first beam to generate a bending moment, and , Indicates the current excitation voltage of the ceramic piezoelectric piece The strain generated by the excitation of , is the deformation of the ceramic piezoelectric piece; is the length of the ceramic piezoelectric piece, is the thickness of the ceramic piezoelectric sheet, represents the piezoelectric constant of the ceramic piezoelectric piece, represents the excitation voltage amplitude, is pi, represents the frequency of the excitation voltage, Indicates the incentive time, represents the elastic modulus of the first beam, represents the moment of inertia of the first beam, represents the thickness of the first beam, Indicates the length of the first beam.

8. The long wave communication method based on a vibration beam according to claim 6, characterized in that: The magnetic field strength for: in, represents the vacuum permeability, represents the magnetic dipole moment, represents the ordinate of any point P(a, b) in space, represents the vibration displacement, represents the horizontal coordinate of any point P(a, b) in space, represents pi; The induced electromotive force for: in, Indicates the number of turns of the coil, represents the magnetic flux through the coil and , represents the cross-sectional area of ​​the coil, represents the magnetic field strength, and , represents the vacuum permeability, represents the magnetic dipole moment, represents the ordinate of any point P(a, b) in space, represents the vibration displacement, represents the horizontal coordinate of any point P(a, b) in space, represents pi, Indicates the incentive time.

9. The long wave communication method based on a vibration beam according to any one of claims 6 to 8, characterized in that: The step S6 comprises: S61: taking the maximum value of the induced electromotive force as the signal strength; S62: Determine whether the signal strength of each permanent magnet is equal to the signal strength of the rigid connector. If so, proceed to step S63; otherwise, adjust the current excitation voltage value and return to step S1; S63: Encode the frequency and time information of the excitation signal to obtain encoded data; S64: Decode the encoded data using the SLs signal analysis method to achieve communication.

Images