CN111006702A - Passive ultrasonic sensor and method - Google Patents
Passive ultrasonic sensor and method Download PDFInfo
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- CN111006702A CN111006702A CN201911307541.8A CN201911307541A CN111006702A CN 111006702 A CN111006702 A CN 111006702A CN 201911307541 A CN201911307541 A CN 201911307541A CN 111006702 A CN111006702 A CN 111006702A
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- G01D5/48—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using wave or particle radiation means
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Abstract
The invention belongs to the technical field of computer interaction, and particularly relates to a passive ultrasonic sensor and a method, wherein the passive ultrasonic sensor comprises the following steps: the ultrasonic sensor comprises a sensor shell, an ultrasonic sensor part and a sensor energy supply part; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; the sensor energizing part includes: a transformer; the transformer is elastically connected with a magnet through a spring; a metal coil is arranged around the outer part of the magnet; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the induction device has the advantage of high induction accuracy, and meanwhile, an external power supply is not required to be provided.
Description
Technical Field
The invention belongs to the technical field of sensors, and particularly relates to a passive ultrasonic sensor and a method.
Background
An ultrasonic sensor is a sensor that converts an ultrasonic signal into another energy signal (typically an electrical signal). Ultrasonic waves are mechanical waves with a vibration frequency higher than 20 kHz. It has the features of high frequency, short wavelength, less diffraction, high directivity, directional propagation, etc. The penetration of ultrasonic waves into liquids and solids is great, especially in sunlight-opaque solids. Ultrasonic waves hitting impurities or interfaces can generate significant reflection to form reflection echoes, and hitting moving objects can generate Doppler effect. The ultrasonic sensor is widely applied to the aspects of industry, national defense, biomedicine and the like.
A commonly used ultrasonic sensor is composed of a piezoelectric wafer, and can transmit ultrasonic waves and receive ultrasonic waves. The low-power ultrasonic probe has a detection function. It has many different structures, including a straight probe (longitudinal wave), a tilted probe (transverse wave), a surface wave probe (surface wave), a lamb wave probe (lamb wave), a dual probe (one probe for transmission and one probe for reception), etc.
Ultrasound sensing technology is used in different aspects of production practice, while medical applications are one of its most prominent applications, and the application of ultrasound sensing technology is exemplified below by medicine. The medical application of ultrasound is mainly to diagnose diseases, and it has become an indispensable diagnostic method in clinical medicine. The advantages of ultrasonic diagnosis are: no pain and no damage to the examined person, simple method, clear imaging, high diagnosis accuracy and the like. Therefore, the popularization is easy, and the medical nursing bed is popular with medical workers and patients. Ultrasound diagnosis can be based on different medical principles, of which we look at a representative so-called type a method. This method uses reflection of ultrasonic waves. When ultrasonic waves propagate in human tissues and encounter an interface of two media with different acoustic impedances, a reflected echo is generated at the interface. When each reflecting surface is met, the echo is displayed on the screen of the oscilloscope, and the impedance difference of the two interfaces also determines the amplitude of the echo.
In the industrial sector, typical applications of ultrasound are both non-destructive inspection of metals and ultrasonic thickness measurement. In the past, many techniques have been hampered by the inability to detect the interior of object tissue, and the advent of ultrasonic sensing technology has transformed this situation. Of course, more ultrasonic sensors are fixedly mounted on different devices to detect the signals needed by people 'silently'. In future applications, ultrasonic waves will be combined with information technology and new material technology, and more intelligent and high-sensitivity ultrasonic sensors will appear.
Disclosure of Invention
Accordingly, the present invention is directed to a passive ultrasonic sensor and a method thereof, which has the advantage of high sensing accuracy and does not need to provide an external power source.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a passive ultrasonic sensor comprising: the ultrasonic sensor comprises a sensor shell, an ultrasonic sensor part and a sensor energy supply part; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; the sensor energizing part includes: a transformer; the transformer is elastically connected with a magnet through a spring; a metal coil is arranged around the outer part of the magnet; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the ultrasonic sensor portion includes: a transmitting section, a receiving section, and an analyzing section; the transmitting part comprises a first transmitting part and a second transmitting part, the first transmitting part and the second transmitting part both transmit ultrasonic waves, and the receiving part receives reflected ultrasonic waves and direct ultrasonic waves; the analysis part sequentially carries out the steps of direct ultrasonic wave filtering, reflected ultrasonic wave conversion and frequency spectrum drawing according to the received reflected ultrasonic wave and the received direct ultrasonic wave; wherein the direct ultrasonic filtering performs the steps of: calculating a time delay between the direct ultrasonic wave of the first transmitting section and the direct ultrasonic wave of the second transmitting section received by the receiving section by fourier transform using the following formula:
wherein r is1(t) direct ultrasound of the first emission part, Fr1(t) is its corresponding fourier transform; r is2(t) direct ultrasound of the second transmitting part, F*[r2(t)]The conjugate of its corresponding fourier transform; f is F [ r ]1(t) and F*[r2(t)]Corresponding frequency, x is the unknown quantity of Fourier transform; recalculating direct ultrasound for the first transmit portionCross-correlation coefficient with direct ultrasound of the second transmit part:
wherein,
is represented by r2(t) an inverse fourier transform; will be provided with
Amplifying by c times to obtain reflected ultrasonic waves after direct ultrasonic wave filtering:
further, the method of reflected ultrasonic wave conversion performs the steps of: the reflected ultrasonic wave is expressed by the following formula:
wherein α is an amplitude constant, fcIs the carrier frequency, TsIs a period, tau (t) is a time delay parameter, B is a bandwidth, N1Is a rate constant, set to 3; the reflected ultrasonic wave is converted into a baseband signal by the following formula:
carrying out Fourier transform on the baseband signal to obtain a frequency spectrum, wherein according to the frequency spectrum, the phase of the obtained baseband signal is as follows: phi (t) ═ 2 pi fcτ(t)。
Further, the fourier transform is performed on the baseband signal to obtain a frequency spectrum, and according to the frequency spectrum, the phase of the obtained baseband signal is: phi (t) ═ 2 pi fcThe method of τ (t) performs the following steps: selecting a frequency of
The frequency point signal b (t); obtaining:
and taking the phase of the frequency point signal to obtain the frequency spectrum of the baseband signal.
Furthermore, the transformer generates vibration in the operation process, the transformer vibrates to drive the spring to perform reciprocating elastic motion, so as to drive the magnet connected with the spring to move, and the magnetic force lines are cut to generate electric energy which is output to the ultrasonic sensor part through the rectifying circuit.
Further, the rectifier circuit includes: two capacitors, respectively: a first capacitor and a second capacitor; a transistor and a diode; the first capacitor and the second capacitor, and the diode are sequentially connected in series between the metal coil and the ultrasonic sensor portion, the second capacitor is connected between one of a source region and a drain region of the transistor and the gate electrode, the other of the source region and the drain region of the transistor is connected to the ultrasonic sensor portion, and the ultrasonic sensor portion is connected to the analysis portion.
A passive ultrasonic sensing method, the method performing the steps of: the sensor shell, the ultrasonic sensor part and the sensor energy supply part form an ultrasonic sensor; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; the transformer generates vibration in the operation process, the transformer vibrates to drive the spring to perform reciprocating elastic motion, further drives the magnet connected with the spring to move, cuts magnetic lines of force to generate electric energy, and the electric energy is output to the ultrasonic sensor part through the rectifying circuit.
Further, the sensor energizing section includes: a transformer; the transformer is elastically connected with a magnet through a spring; the outer part of the magnet is surrounded by metalA coil; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the ultrasonic sensor portion includes: a transmitting section, a receiving section, and an analyzing section; the transmitting part comprises a first transmitting part and a second transmitting part, the first transmitting part and the second transmitting part both transmit ultrasonic waves, and the receiving part receives reflected ultrasonic waves and direct ultrasonic waves; the analysis part sequentially carries out the steps of direct ultrasonic wave filtering, reflected ultrasonic wave conversion and frequency spectrum drawing according to the received reflected ultrasonic wave and the received direct ultrasonic wave; wherein the direct ultrasonic filtering performs the steps of: calculating a time delay between the direct ultrasonic wave of the first transmitting section and the direct ultrasonic wave of the second transmitting section received by the receiving section by fourier transform using the following formula:
wherein r is1(t) direct ultrasound of the first emission part, Fr1(t) is its corresponding fourier transform; r is2(t) direct ultrasound of the second transmitting part, F*[r2(t)]The conjugate of its corresponding fourier transform; f is F [ r ]1(t) and F*[r2(t)]Corresponding frequency, x is the unknown quantity of Fourier transform; and then, calculating the cross-correlation coefficient between the direct ultrasonic wave of the first transmitting part and the direct ultrasonic wave of the second transmitting part:
wherein,
is represented by r2(t) an inverse fourier transform; will be provided with
Amplifying by c times to obtain reflected ultrasonic waves after direct ultrasonic wave filtering:
further, the method of reflected ultrasonic wave conversion performs the steps of: the reflected ultrasonic wave is expressed by the following formula:
wherein α is an amplitude constant, fcIs the carrier frequency, TsIs a period, tau (t) is a time delay parameter, B is a bandwidth, N1Is a rate constant, set to 3; the reflected ultrasonic wave is converted into a baseband signal by the following formula:
carrying out Fourier transform on the baseband signal to obtain a frequency spectrum, wherein according to the frequency spectrum, the phase of the obtained baseband signal is as follows: phi (t) ═ 2 pi fcτ(t)。
Further, the fourier transform is performed on the baseband signal to obtain a frequency spectrum, and according to the frequency spectrum, the phase of the obtained baseband signal is: phi (t) ═ 2 pi fcThe method of τ (t) performs the following steps: selecting a frequency of
The frequency point signal b (t); obtaining:
and taking the phase of the frequency point signal to obtain the frequency spectrum of the baseband signal.
Further, the rectifier circuit includes: two capacitors, respectively: a first capacitor and a second capacitor; a transistor and a diode; the first capacitor and the second capacitor, and the diode are sequentially connected in series to the metal coil and the ultrasonic sensor portion, the second capacitor is connected between one of a source region and a drain region of the transistor and a gate electrode, and the other of the source region and the drain region of the transistor is connected to the ultrasonic sensor portion.
The passive ultrasonic sensor and the method have the following beneficial effects: vibration can be generated in the operation process of the transformer, the mechanism for generating electric energy cuts magnetic lines of force to generate electric energy, and the electric energy is processed and output to the sensor through a corresponding circuit by utilizing the vibration of the transformer, so that the sensor does not need an extra power supply, does not need to replace a battery, and has long service life. Meanwhile, the transmitting part of the ultrasonic sensor part of the invention uses two groups of two sounding parts to simultaneously send out ultrasonic waves, and the receiving part can receive two different reflected ultrasonic waves and direct ultrasonic waves after receiving the ultrasonic waves.
Drawings
Fig. 1 is a schematic structural diagram of a passive ultrasonic sensor provided in an embodiment of the present invention;
FIG. 2 is a schematic method flow diagram of a passive ultrasonic sensing method according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a comparison test of the passive ultrasonic sensor and the method provided by the embodiment of the invention with the change of the accuracy rate along with the change of the distance from the measured object and the prior art.
Wherein, 1-experimental graph of the invention, 2-experimental graph of the prior art.
Detailed Description
The method of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments of the invention.
Example 1
A passive ultrasonic sensor comprising: the ultrasonic sensor comprises a sensor shell, an ultrasonic sensor part and a sensor energy supply part; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; the sensor energizing part includes:a transformer; the transformer is elastically connected with a magnet through a spring; a metal coil is arranged around the outer part of the magnet; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the ultrasonic sensor portion includes: a transmitting section, a receiving section, and an analyzing section; the transmitting part comprises a first transmitting part and a second transmitting part, the first transmitting part and the second transmitting part both transmit ultrasonic waves, and the receiving part receives reflected ultrasonic waves and direct ultrasonic waves; the analysis part sequentially carries out the steps of direct ultrasonic wave filtering, reflected ultrasonic wave conversion and frequency spectrum drawing according to the received reflected ultrasonic wave and the received direct ultrasonic wave; wherein the direct ultrasonic filtering performs the steps of: calculating a time delay between the direct ultrasonic wave of the first transmitting section and the direct ultrasonic wave of the second transmitting section received by the receiving section by fourier transform using the following formula:
wherein r is1(t) direct ultrasound of the first emission part, Fr1(t) is its corresponding fourier transform; r is2(t) direct ultrasound of the second transmitting part, F*[r2(t)]The conjugate of its corresponding fourier transform; f is F [ r ]1(t) and F*[r2(t)]Corresponding frequency, x is the unknown quantity of Fourier transform; and then, calculating the cross-correlation coefficient between the direct ultrasonic wave of the first transmitting part and the direct ultrasonic wave of the second transmitting part:
wherein,
is represented by r2(t) an inverse fourier transform; will be provided with
Amplifying by c times to obtainFiltering reflected ultrasonic waves after direct ultrasonic waves:
specifically, the transmitting part of the ultrasonic sensor part of the invention uses two groups of two sounding parts to simultaneously send out ultrasonic waves, and the receiving part can receive two different reflected ultrasonic waves and direct ultrasonic waves after receiving the ultrasonic waves.
Specifically, the propagation law of the ultrasonic wave in the medium, such as reflection, refraction, diffraction, scattering, etc., is not substantially different from the propagation law of the audible sound wave. But the wavelength of the ultrasonic waves is very short, only a few centimeters or even a few thousandths of a millimeter. Compared to audible sound waves, ultrasonic waves have many unusual characteristics: propagation characteristics-the wavelength of the ultrasound wave is very short, the size of the typical obstacle is many times larger than the wavelength of the ultrasound wave, and therefore the diffraction power of the ultrasound wave is poor, it can be directionally propagated straight in a homogeneous medium, the characteristics being more pronounced the shorter the wavelength of the ultrasound wave is. Power characteristics-when sound is propagated in air, the particles in the air are forced to vibrate back and forth to do work on the particles. The sound wave power is a physical quantity representing how fast the sound wave works. At the same intensity, the higher the frequency of the sound wave, the greater the power it has. Since the ultrasonic wave has a high frequency, its power is very large compared to a general sound wave. Cavitation-when the ultrasonic wave has an alternating cycle of positive and negative pressure in the transmission process of the medium, the ultrasonic wave extrudes the medium molecules to change the original density of the medium and increase the density of the medium in the positive pressure phase; in the negative pressure phase, the medium molecules are thinned and further dispersed, the density of the medium is reduced, and when ultrasonic waves with large enough amplitude act on the liquid medium, the average distance between the medium molecules exceeds the critical molecular distance which keeps the liquid medium unchanged, and the liquid medium is broken to form the micro-bubbles. These small voids rapidly expand and close, causing violent impact between the liquid particles, thereby creating pressures of several thousand to tens of thousands of atmospheres. The violent interaction between the particles can raise the temperature of the liquid suddenly to play a good role in stirring, so that two immiscible liquids (such as water and oil) are emulsified, the dissolution of a solute is accelerated, and a chemical reaction is accelerated. The various effects caused by the action of ultrasound in a liquid are known as cavitation of the ultrasound.
Example 2
On the basis of the above embodiment, the method of reflected ultrasonic wave conversion performs the following steps: the reflected ultrasonic wave is expressed by the following formula:
wherein α is an amplitude constant, fcIs the carrier frequency, TsIs a period, tau (t) is a time delay parameter, B is a bandwidth, N1Is a rate constant, set to 3; the reflected ultrasonic wave is converted into a baseband signal by the following formula:
carrying out Fourier transform on the baseband signal to obtain a frequency spectrum, wherein according to the frequency spectrum, the phase of the obtained baseband signal is as follows: phi (t) ═ 2 pi fcτ(t)。
Specifically, the frequency spectrum is a short term for frequency spectral density, and is a distribution curve of frequency. The complex oscillations are decomposed into harmonic oscillations of different amplitudes and different frequencies, and the pattern of the amplitude of these harmonic oscillations arranged in terms of frequency is called the frequency spectrum. Frequency spectrum is widely used in acoustic, optical and radio technologies. The frequency spectrum introduces the study of the signal from the time domain to the frequency domain, leading to a more intuitive understanding. The spectrum into which the complicated mechanical vibration is decomposed is called a mechanical vibration spectrum, the spectrum into which the acoustic vibration is decomposed is called a sound spectrum, the spectrum into which the optical vibration is decomposed is called a spectrum, and the spectrum into which the electromagnetic vibration is decomposed is called an electromagnetic spectrum, and the spectrum is generally included in the range of the electromagnetic spectrum. Many basic properties of the complex vibration can be known by analyzing the frequency spectrum of various vibrations, so that the frequency spectrum analysis has become a basic method for analyzing various complex vibrations.
After the reflected ultrasonic waves are converted into baseband signals, frequency spectrums can be obtained through Fourier transform, and then phases of the baseband signals can be obtained according to the law of the frequency spectrums, so that subsequent frequency spectrogram can be drawn conveniently.
Example 3
On the basis of the previous embodiment, the fourier transform is performed on the baseband signal to obtain a frequency spectrum, and according to the frequency spectrum, the phase of the obtained baseband signal is: phi (t) ═ 2 pi fcThe method of τ (t) performs the following steps: selecting a frequency of
The frequency point signal b (t); obtaining:
and taking the phase of the frequency point signal to obtain the frequency spectrum of the baseband signal.
Example 4
On the basis of the previous embodiment, the transformer generates vibration in the operation process, the transformer vibrates to drive the spring to perform reciprocating elastic motion, further drives the magnet connected with the spring to move, cuts magnetic lines of force to generate electric energy, and the electric energy is output to the ultrasonic sensor part through the rectifying circuit.
Example 5
On the basis of the above embodiment, the rectifier circuit includes: two capacitors, respectively: a first capacitor and a second capacitor; a transistor and a diode; the first capacitor and the second capacitor, and the diode are sequentially connected in series to the metal coil and the ultrasonic sensor portion, the second capacitor is connected between one of a source region and a drain region of the transistor and a gate electrode, and the other of the source region and the drain region of the transistor is connected to the ultrasonic sensor portion.
Specifically, a "rectifying circuit" is a circuit that converts ac power to dc power. Most of the rectifier circuits are composed of a transformer, a main rectifier circuit, a filter and the like. It is widely applied in the fields of speed regulation of direct current motors, excitation regulation of generators, electrolysis, electroplating and the like. After the 70 s of the 20 th century, the main circuit is composed of silicon rectifier diodes and thyristors. The filter is connected between the main circuit and the load and is used for filtering alternating current components in the pulsating direct current voltage. Whether the transformer is arranged or not depends on the specific situation. The transformer is used for matching the alternating current input voltage and the direct current output voltage and electrically isolating the alternating current power grid from the rectifying circuit.
The rectifying circuit is used for converting alternating current with lower voltage output by the alternating current voltage reduction circuit into unidirectional pulsating direct current, namely the rectifying process of the alternating current, and mainly comprises rectifying diodes. The voltage after passing through the rectifier circuit is not an alternating voltage but a mixed voltage containing a direct voltage and an alternating voltage. It is customarily known as a unidirectional pulsating dc voltage.
Example 6
A passive ultrasonic sensing method, the method performing the steps of: the sensor shell, the ultrasonic sensor part and the sensor energy supply part form an ultrasonic sensor; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; the transformer generates vibration in the operation process, the transformer vibrates to drive the spring to perform reciprocating elastic motion, further drives the magnet connected with the spring to move, cuts magnetic lines of force to generate electric energy, and the electric energy is output to the ultrasonic sensor part through the rectifying circuit.
Example 7
On the basis of the above embodiment, the sensor power supply section includes: a transformer; the transformer is elastically connected with a magnet through a spring; a metal coil is arranged around the outer part of the magnet; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the ultrasonic sensor portion includes: transmitting partA receiving section and an analyzing section; the transmitting part comprises a first transmitting part and a second transmitting part, the first transmitting part and the second transmitting part both transmit ultrasonic waves, and the receiving part receives reflected ultrasonic waves and direct ultrasonic waves; the analysis part sequentially carries out the steps of direct ultrasonic wave filtering, reflected ultrasonic wave conversion and frequency spectrum drawing according to the received reflected ultrasonic wave and the received direct ultrasonic wave; wherein the direct ultrasonic filtering performs the steps of: calculating a time delay between the direct ultrasonic wave of the first transmitting section and the direct ultrasonic wave of the second transmitting section received by the receiving section by fourier transform using the following formula:
wherein r is1(t) direct ultrasound of the first emission part, Fr1(t) is its corresponding fourier transform; r is2(t) direct ultrasound of the second transmitting part, F*[r2(t)]The conjugate of its corresponding fourier transform; f is F [ r ]1(t) and F r2(t)]Corresponding frequency, x is the unknown quantity of Fourier transform; and then, calculating the cross-correlation coefficient between the direct ultrasonic wave of the first transmitting part and the direct ultrasonic wave of the second transmitting part:
wherein,
is represented by r2(t) an inverse fourier transform; will be provided with
Amplifying by c times to obtain reflected ultrasonic waves after direct ultrasonic wave filtering:
specifically, the phenomenon of induced electromotive force is generated due to the change of magnetic flux, and when a part of conductors of a closed circuit do the motion of cutting magnetic induction lines in a magnetic field, current is generated in the conductors, and the phenomenon is called electromagnetic induction. Part of the conductor of the closed circuit makes a cutting magnetic induction line movement in a magnetic field, and current is generated in the conductor. This phenomenon is called electromagnetic induction. The resulting current is called the induced current. This is the electromagnetic induction phenomenon that junior middle school physics textbook is for the student to understand the definition, can not summarize the electromagnetic induction phenomenon comprehensively: the area of the closed coil is unchanged, the magnetic field intensity is changed, the magnetic flux is also changed, and the electromagnetic induction phenomenon also occurs. So the exact definition is as follows: the phenomenon of induced electromotive force is generated due to the change of magnetic flux.
Example 8
On the basis of the above embodiment, the method of reflected ultrasonic wave conversion performs the following steps: the reflected ultrasonic wave is expressed by the following formula:
wherein α is an amplitude constant, fcIs the carrier frequency, TsIs a period, tau (t) is a time delay parameter, B is a bandwidth, N1Is a rate constant, set to 3; the reflected ultrasonic wave is converted into a baseband signal by the following formula:
carrying out Fourier transform on the baseband signal to obtain a frequency spectrum, wherein according to the frequency spectrum, the phase of the obtained baseband signal is as follows: phi (t) ═ 2 pi fcτ(t)。
Example 9
On the basis of the previous embodiment, the fourier transform is performed on the baseband signal to obtain a frequency spectrum, and according to the frequency spectrum, the phase of the obtained baseband signal is: phi (t) ═ 2 pi fcThe method of τ (t) performs the following steps: selecting a frequency of
The frequency point signal b (t); obtaining:
and taking the phase of the frequency point signal to obtain the frequency spectrum of the baseband signal.
Example 10
On the basis of the above embodiment, the rectifier circuit includes: two capacitors, respectively: a first capacitor and a second capacitor; a transistor and a diode; the first capacitor and the second capacitor, and the diode are sequentially connected in series to the metal coil and the ultrasonic sensor portion, the second capacitor is connected between one of a source region and a drain region of the transistor and a gate electrode, and the other of the source region and the drain region of the transistor is connected to the ultrasonic sensor portion.
The above description is only an embodiment of the present invention, but not intended to limit the scope of the present invention, and any structural changes made according to the present invention should be considered as being limited within the scope of the present invention without departing from the spirit of the present invention.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process and related description of the system described above may refer to the corresponding process in the foregoing method embodiments, and will not be described herein again.
It should be noted that, the system provided in the foregoing embodiment is only illustrated by dividing the functional modules, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the modules or steps in the embodiment of the present invention are further decomposed or combined, for example, the modules in the foregoing embodiment may be combined into one module, or may be further split into multiple sub-modules, so as to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the modules or steps, and are not to be construed as unduly limiting the present invention.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes and related descriptions of the storage device and the processing device described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
Those of skill in the art would appreciate that the various illustrative modules, method steps, and modules described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that programs corresponding to the software modules, method steps may be located in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. To clearly illustrate this interchangeability of electronic hardware and software, various illustrative components and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as electronic hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing or implying a particular order or sequence.
The terms "comprises," "comprising," or any other similar term are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.
Claims (10)
1. A passive ultrasonic sensor comprising: the ultrasonic sensor comprises a sensor shell, an ultrasonic sensor part and a sensor energy supply part; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; characterized in that the sensor energizing part comprises: a transformer; the transformer is elastically connected with a magnet through a spring; a metal coil is arranged around the outer part of the magnet; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the ultrasonic sensor portion includes: a transmitting section, a receiving section, and an analyzing section; the transmitting part comprises a first transmitting part and a second transmitting part, the first transmitting part and the second transmitting part both transmit ultrasonic waves, and the receiving part receives reflected ultrasonic waves and direct ultrasonic waves; the analysis part sequentially carries out the steps of direct ultrasonic wave filtering, reflected ultrasonic wave conversion and frequency spectrum drawing according to the received reflected ultrasonic wave and the received direct ultrasonic wave; wherein the direct ultrasonic filtering performs the steps of: calculating a time delay between the direct ultrasonic wave of the first transmitting section and the direct ultrasonic wave of the second transmitting section received by the receiving section by fourier transform using the following formula:
wherein r is1(t) direct ultrasound of the first emission part, Fr1(t) is its corresponding fourier transform; r is2(t) direct ultrasound of the second transmitting part, F*[r2(t)]The conjugate of its corresponding fourier transform; f is F [ r ]1(t) and F*[r2(t)]Corresponding frequency, x is the unknown quantity of Fourier transform; and then, calculating the cross-correlation coefficient between the direct ultrasonic wave of the first transmitting part and the direct ultrasonic wave of the second transmitting part:
wherein,
is represented by r2(t) an inverse fourier transform; will be provided with
Amplifying by c times to obtain reflected ultrasonic waves after direct ultrasonic wave filtering:
2. the system of claim 1, wherein the method of reflected ultrasound wave conversion performs the steps of: the reflected ultrasonic wave is expressed by the following formula:
wherein α is an amplitude constant, fcIs the carrier frequency, TsIs a period, tau (t) is a time delay parameter, B is a bandwidth, N1Is a rate constant, set to 3; the reflected ultrasonic wave is converted into a baseband signal by the following formula:
carrying out Fourier transform on the baseband signal to obtain a frequency spectrum, wherein according to the frequency spectrum, the phase of the obtained baseband signal is as follows: phi (t) ═ 2 pi fcτ(t)。
3. The system of claim 2, wherein the fourier transform of the baseband signal yields a spectrum from which the phase of the baseband signal is derived as: phi (t) ═ 2 pi fcThe method of τ (t) performs the following steps: selecting a frequency of
The frequency point signal b (t); obtaining:
and taking the phase of the frequency point signal to obtain the frequency spectrum of the baseband signal.
4. The system of claim 1, wherein the transformer generates vibration during operation, the transformer vibration drives the spring to perform reciprocating elastic movement, thereby driving the magnet connected with the spring to move, and the magnetic force lines are cut to generate electric energy which is output to the ultrasonic sensor part through the rectifying circuit.
5. The system of claim 3, wherein the rectification circuit comprises: two capacitors, respectively: a first capacitor and a second capacitor; a transistor and a diode; the first capacitor and the second capacitor, and the diode are sequentially connected in series to the metal coil and the ultrasonic sensor portion, the second capacitor is connected between one of a source region and a drain region of the transistor and a gate electrode, and the other of the source region and the drain region of the transistor is connected to the ultrasonic sensor portion.
6. A passive ultrasound sensing method based on the system of one of claims 1 to 5, characterized in that the method performs the following steps: the sensor shell, the ultrasonic sensor part and the sensor energy supply part form an ultrasonic sensor; the ultrasonic sensor part and the sensor energy supply part are both arranged in the sensor shell; the sensor energy supply part is used for supplying energy to the ultrasonic sensor part; the transformer generates vibration in the operation process, the transformer vibrates to drive the spring to perform reciprocating elastic motion, further drives the magnet connected with the spring to move, cuts magnetic lines of force to generate electric energy, and the electric energy is output to the ultrasonic sensor part through the rectifying circuit.
7. The method of claim 6, wherein the sensor energizing section comprises: a transformer; the transformer is elastically connected with a magnet through a spring; a metal coil is arranged around the outer part of the magnet; the metal coil is connected with the ultrasonic sensor part through a rectifying circuit; the ultrasonic sensor portion includes: a transmitting section, a receiving section, and an analyzing section; the transmitting part comprises a first transmitting part and a second transmitting part, the first transmitting part and the second transmitting part both transmit ultrasonic waves, and the receiving part receives reflected ultrasonic waves and direct ultrasonic waves; the analysis part sequentially carries out the steps of direct ultrasonic wave filtering, reflected ultrasonic wave conversion and frequency spectrum drawing according to the received reflected ultrasonic wave and the received direct ultrasonic wave; wherein the direct ultrasonic filtering performs the steps of: calculating a time delay between the direct ultrasonic wave of the first transmitting section and the direct ultrasonic wave of the second transmitting section received by the receiving section by fourier transform using the following formula:
wherein r is1(t) direct ultrasound of the first emission part, Fr1(t) is its corresponding fourier transform; r is2(t) direct ultrasound of the second transmitting part, F*[r2(t)]The conjugate of its corresponding fourier transform; f is F [ r ]1(t) and F*[r2(t)]Corresponding frequency, x is the unknown quantity of Fourier transform; and then, calculating the cross-correlation coefficient between the direct ultrasonic wave of the first transmitting part and the direct ultrasonic wave of the second transmitting part:
wherein,
is represented by r2(t) an inverse fourier transform; will be provided with
Amplifying by c times to obtain reflected ultrasonic waves after direct ultrasonic wave filtering:
8. the method of claim 7, wherein the method of reflected ultrasound wave conversion performs the steps of: the reflected ultrasonic wave is expressed by the following formula:
wherein α is an amplitude constant, fcIs the carrier frequency, TsIs a period, tau (t) is a time delay parameter, B is a bandwidth, N1Is a rate constant, set to 3; the reflected ultrasonic wave is converted into a baseband signal by the following formula:
carrying out Fourier transform on the baseband signal to obtain a frequency spectrum, wherein according to the frequency spectrum, the phase of the obtained baseband signal is as follows: phi (t) ═ 2 pi fcτ(t)。
9. The method of claim 8, wherein the fourier transform of the baseband signal yields a spectrum from which the phase of the baseband signal is derived as: phi (t) ═ 2 pi fcThe method of τ (t) performs the following steps: selecting a frequency of
The frequency point signal b (t); obtaining:
and taking the phase of the frequency point signal to obtain the frequency spectrum of the baseband signal.
10. The method of claim 9, wherein the rectifier circuit comprises: two capacitors, respectively: a first capacitor and a second capacitor; a transistor and a diode; the first capacitor and the second capacitor, and the diode are sequentially connected in series between the metal coil and the ultrasonic sensor portion, the second capacitor is connected between one of a source region and a drain region of the transistor and the gate electrode, the other of the source region and the drain region of the transistor is connected to the ultrasonic sensor portion, and the ultrasonic sensor portion is connected to the analysis portion.
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