TWI805425B - System and method for determining time of light of ultrasound wave - Google Patents

Abstract

An ultrasonic time-of-flight determining system includes a sound-wave transmitting transducer, a sound-wave receiving transducer and a computing circuit. The calculation circuit sets that a first sound wave emitted by the sound-wave transmitting transducer includes a low-amplitude signal and a high-amplitude signal, and takes the starting point of the high-amplitude signal as a reference starting point. The calculation circuit also determines an amplitude turning point in a second sound wave received by the sound-wave receiving transducer, takes the amplitude turning point as a reference end point, and takes the time difference between the reference starting point and the reference end point as the time-of-flight of the sound wave.

Description

Ultrasonic time-of-flight judging system and method

This disclosure relates to a method and system for judging the time of flight of ultrasonic waves.

When propagating in the gas, the transmission rate of the sound wave varies with the temperature. Through the relationship between the sound wave speed and the temperature, the temperature can be calculated after the sound wave speed is obtained by calculating the flight time, and the sound wave data of multiple paths can be reconstructed. Two-dimensional temperature distribution. However, the sound wave pattern is easily disturbed by factors such as environmental noise, air flow, and gas temperature, which will affect the calculation of the sound wave velocity. On the other hand, acoustic wave sensors mostly use vibration to generate sound wave signals. Objects often need a certain number of vibrations from the beginning to stabilization. Even if a high-amplitude vibration signal is input, if the frequency is not enough, the output cannot reach the preset size. If only Outputting the same high-amplitude serial drive signal may distort the waveform due to temperature changes, making it difficult to judge the flight time stably.

Embodiments of the present disclosure provide an ultrasonic time-of-flight judging system, including an acoustic wave emitting sensor, an acoustic wave receiving sensor, and a calculation circuit. The sound wave emission sensor is used for emitting the first sound wave. The sound wave receiving sensor is used for receiving the second sound wave corresponding to the first sound wave. The calculation circuit is connected to the sound wave transmitting sensor and the sound wave receiving sensor for setting the first sound wave including a low amplitude signal and a high amplitude signal, the high amplitude signal is followed by the low amplitude signal, and the starting point of the high amplitude signal is used as a reference starting point. The calculation circuit is used to judge the turning point of the amplitude in the second sound wave, the turning point of the amplitude is taken as the reference end point, and the time difference between the reference start point and the reference end point is taken as the flight time of the sound wave.

In some embodiments, the calculation circuit obtains the receiving angle of the sound wave receiving sensor relative to the sound wave emitting sensor. When the receiving angle is smaller than the preset angle, the calculation circuit calculates the average value of the amplitude of the second sound wave. After the average value is calculated, the calculation circuit judges whether the amplitude of the second sound wave exceeds the average value, and if so, judges whether the amplitude of the second sound wave shows an upward trend and remains stable. If the amplitude of the second sound wave exceeds the average value, shows an upward trend and remains stable, the calculation circuit obtains the time point when the amplitude of the second sound wave exceeds the average value for the first time as a reference termination point.

In some embodiments, the calculation circuit determines whether the slope of the amplitude of the second sound wave is positive at a plurality of consecutive sampling points to determine whether the amplitude of the second sound wave shows an upward trend. The computing circuit also judges whether the difference between the amplitude of the second sound wave before and after the sampling point is smaller than a preset value, so as to judge whether the second sound wave remains stable.

In some embodiments, when the receiving angle is greater than or equal to a preset angle, the calculation circuit performs envelope processing on the second sound wave to obtain an envelope curve. The calculation circuit judges whether the envelope curve is greater than a preset amplitude to obtain the first wave group and the second wave group, wherein the first wave group and the second wave group are not connected. The calculation circuit obtains the time point of the trough between the first wave group and the second wave group as a reference termination point.

In some embodiments, the calculation circuit determines the preset amplitude according to the distance between the sound wave receiving sensor and the sound wave emitting sensor, wherein the distance is negatively correlated with the preset amplitude.

From another point of view, the embodiments of the present disclosure provide a method for judging ultrasonic time-of-flight, which is suitable for computing circuits. The ultrasonic time-of-flight judgment method includes: setting the first sound wave to include a low-amplitude signal and a high-amplitude signal, the high-amplitude signal following the low-amplitude signal, and taking the starting point of the high-amplitude signal as a reference starting point; The transmitting sensor sends out the first sound wave; the second sound wave corresponding to the first sound wave is received by the sound wave receiving sensor; and the amplitude turning point in the second sound wave is judged, and the amplitude turning point is regarded as a reference end point, and the reference start point and the reference end point The time gap between them is regarded as the sound wave flight time.

In some embodiments, the ultrasonic time-of-flight judging method further includes: obtaining the receiving angle of the acoustic wave receiving sensor relative to the acoustic wave emitting sensor; when the receiving angle is less than the preset angle, calculating the average value of the amplitude of the second acoustic wave; After the average value, judge whether the amplitude of the second sound wave exceeds the average value, and if so, judge whether the amplitude of the second sound wave shows an upward trend and remains stable; and if the amplitude of the second sound wave exceeds the average value, presents an upward trend and remains stable, The time point at which the amplitude of the second sound wave exceeds the average value for the first time is taken as the reference termination point.

In some embodiments, the ultrasonic time-of-flight judging method further includes: judging whether the slope of the amplitude of the second sound wave is positive at a plurality of consecutive sampling points to judge whether the amplitude of the second sound wave presents an upward trend; and judging the amplitude of the second sound wave Whether the amplitude difference between the preceding and the following sampling points is smaller than a preset value is used to determine whether the second sound wave remains stable.

In some embodiments, the ultrasonic time-of-flight judging method further includes: when the receiving angle is greater than or equal to a preset angle, performing envelope processing on the second sound wave to obtain an envelope curve; judging whether the envelope curve is greater than a preset amplitude to obtain a second sound wave A wave group and a second wave group, wherein the first wave group and the second wave group are not connected; and a time point of a trough between the first wave group and the second wave group is obtained as a reference termination point.

In some embodiments, the ultrasonic time-of-flight judging method further includes: determining a preset amplitude according to the distance between the sound wave receiving sensor and the sound wave emitting sensor, wherein the distance is negatively correlated with the preset amplitude.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

The terms "first", "second" and the like used herein do not specifically refer to a sequence or sequence, but are only used to distinguish elements or operations described with the same technical terms.

FIG. 1 is a schematic diagram illustrating an ultrasonic time-of-flight judging system according to an embodiment. Please refer to FIG. 1 , the ultrasonic time-of-flight judging system 100 includes a plurality of ultrasonic sensors UT1-UT12 and a computing circuit 110, wherein the ultrasonic sensor UT1 is used as a sound wave emission sensor (marked as "Tx") to send out the first sound wave , while the other ultrasonic sensors UT2~UT12 are used as sound wave receiving sensors to receive the first sound wave. Since the sound wave will be deformed after being transmitted in the air, the received sound wave is called the second sound wave here. The ultrasonic sensors UT1~UT12 are set at preset positions, so the receiving angle of each acoustic wave receiving sensor relative to the acoustic wave emitting sensor can be known in advance, and the acoustic wave receiving sensors are marked according to the receiving angle, for example, the ultrasonic sensor UT7 The receiving angle is "0" degrees, the receiving angle of the ultrasonic sensor UT2 is "+150" degrees, and so on. In some embodiments, each ultrasonic sensor UT1~UT12 can be used to emit and receive sound waves, but in some embodiments, the ultrasonic sensor UT1 can also use a sensor specially used to emit sound waves, while the other ultrasonic sensors UT2~UT12 A sensor specially used for receiving sound waves may be used, and the present disclosure is not limited thereto. In addition, the above-mentioned sound waves in this embodiment are ultrasonic waves, but the disclosure does not limit the frequency of the sound waves.

The computing circuit 110 may be a microprocessor, a controller, a central processing unit, an application-specific integrated circuit, or any circuit capable of computing. The computing circuit 110 is communicatively connected to the ultrasonic sensors UT1 - UT12 , and this communication connection can be achieved by any wired or wireless communication means. The calculation circuit 110 is used to set the signal in the above-mentioned first sound wave, and judge the flight time of the sound wave according to the second sound wave received, and calculate the temperature distribution of the air according to the flight time of the sound wave, and how to calculate the flight time of the sound wave will be described in detail below time.

In this embodiment, two signals with different amplitudes are added to the sound wave, and the turning point between the signals can be used as a reference point for calculating the flight time. Specifically, FIG. 2 is a schematic diagram of calculating the time-of-flight of sound waves according to an embodiment, the horizontal axis represents time, and the vertical axis represents sound wave intensity. FIG. 2 illustrates the emitted first sound wave and the received second sound wave. The calculation circuit 110 will set the first sound wave to include the low amplitude signal 310 and the high amplitude signal 320, wherein the high amplitude signal 320 follows the low amplitude signal 310, and the starting point of the high amplitude signal 320 is taken as the reference starting point 351, This reference starting point 351 is also a turning point of the signal, which can be used as a reference point for calculating the flight time. The larger the amplitude difference between the low-amplitude signal 310 and the high-amplitude signal 320 , the better. In some embodiments, the amplitude of the high-amplitude signal 320 can be set as the upper limit of the sensor.

The first sound wave will be deformed after propagating in the air. The received signal 330 in the second sound wave corresponds to the low-amplitude signal 310 , while the signal 340 corresponds to the high-amplitude signal 320 . The amplitude of the signal 340 will be significantly greater than that of the signal 330 The amplitude, that is to say, the amplitude of the second sound wave will obviously rise. Here, the amplitude inflection point 352 in the second sound wave is determined, and the amplitude inflection point 352 corresponds to the reference starting point 351 . Next, the amplitude inflection point 352 is regarded as the reference end point, and the time gap between the reference start point 351 and the reference end point (amplitude inflection point 352 ) can be used as the sound wave flight time 360 . In some embodiments, any curvature point algorithm can be used to obtain the amplitude turning point 352 , but the present disclosure is not limited thereto. Since the amplitude of the sound wave is very small when the sensor starts to operate, if the signal-to-noise ratio is not good, the judgment result will be unstable. In this embodiment, the low-amplitude signal 310 is used as the precursor signal, and it is converted into a high-amplitude signal after the amplitude is stable. , so that the signal-to-noise ratio can be improved and the accuracy of judgment can be improved.

度、

度、

度、

度與

度時所接收到的聲波。從圖4可以看出，當接收角度為0~90度時聲波中的振幅有明顯的轉折，但是當接收角度大於120度時則不容易辨識出轉折。在一些實施例中可以採用兩套演算法來計算上述的振幅轉折點352，第一套演算法用於接收角度小於一預設角度(例如120度)時，而第二套演算法則用於接收角度大於等於預設角度時。由於聲波接收傳感器的接收角度是已知，計算電路110可以根據接收角度來判斷採用哪一套演算法。 FIG. 3 is a graph illustrating amplitude attenuation of sound waves at different angles according to an embodiment. Please refer to FIG. 3 , the horizontal axis is the receiving angle, and the vertical axis is the degree of amplitude attenuation (expressed in dB). It can be seen that as the receiving angle increases, the amplitude of the received sound wave also attenuates more. FIG. 4 shows waveforms of second sound waves under different receiving angles according to an embodiment. Please refer to Figure 4, the sound waves 401~406 are respectively when the receiving angle is 0 degrees,

Spend,

Spend,

Spend,

degree and

The received sound waves at degrees. It can be seen from Figure 4 that when the receiving angle is 0 to 90 degrees, the amplitude of the sound wave has an obvious turning point, but when the receiving angle is greater than 120 degrees, it is not easy to identify the turning point. In some embodiments, two sets of algorithms can be used to calculate the above-mentioned amplitude turning point 352. The first set of algorithms is used when the receiving angle is smaller than a preset angle (for example, 120 degrees), and the second set of algorithms is used for the receiving angle. When greater than or equal to the preset angle. Since the receiving angle of the acoustic wave receiving sensor is known, the calculation circuit 110 can determine which algorithm to use according to the receiving angle.

Firstly, the algorithm when the receiving angle is smaller than the preset angle is described. FIG. 5 is a schematic diagram illustrating calculating an amplitude turning point when the receiving angle is smaller than a preset angle according to an embodiment. Please refer to FIG. 5 . FIG. 5 shows the waveform of the received second sound wave, and also shows an enlarged view of the waveform when the signal turns. Firstly, the sound wave received in actual operation is discrete, so there are multiple sampling points on the sound wave, and the present disclosure does not limit the sampling frequency. In the following approach, the amplitude of the sound wave will be obtained. Since the wavelength/frequency of the sound wave is known, the maximum intensity within a wavelength can be taken as the amplitude. The next step is to detect low-amplitude signals. Since the ultrasonic sensor must take a period of time to stabilize, it can be judged whether the change in amplitude over time is within a preset range. If so, it means that the amplitude has stabilized. Beginning to calculate the average value of the amplitude, which can be represented by the dashed line 510 . Next, it is judged whether the amplitude of the sound wave exceeds the average value (dotted line 510), if so, it may be a high-amplitude signal, but in order to avoid misjudgment, two conditions must be met, that is, the amplitude of the second sound wave presents an upward trend, and the amplitude of the sound wave keep it steady. In some embodiments, the slope between two adjacent amplitudes can be calculated, and it is judged whether the slope of the amplitude is positive at consecutive N (can be any positive integer) sampling points, and if so, it means that the amplitude presents an upward trend (corresponding to section 521). When the slope of the amplitude is positive for N consecutive sampling points, it can be judged whether the difference between the amplitude of the sound wave between the previous and subsequent sampling points is smaller than a preset value, if yes, it means that the sound wave has remained stable (corresponding to section 522). When the above three conditions: the amplitude of the sound wave exceeds the average value, the amplitude shows an upward trend, and the amplitude remains stable, the time point when the amplitude of the second sound wave exceeds the average value for the first time is taken as the reference termination point 530 .

FIG. 6 is a schematic diagram illustrating calculating an amplitude turning point when the receiving angle is greater than or equal to a preset angle according to an embodiment. Please refer to FIG. 6 , when the receiving angle is larger than the preset angle, envelope processing is first performed on the second sound wave, that is, the amplitudes of the waves are connected together to form an envelope curve 610 . Next, it is judged whether the envelope curve 610 is greater than a preset amplitude (represented as a dotted line 620) to obtain the first wave group 631 and the second wave group 632. Here, a wave group refers to a continuous wave group greater than a preset amplitude in the envelope curve 610. In the segment, the complexes are not connected, wherein the first complex 631 and the second complex 632 are the two earliest complexes, and the second complex 632 is after the first complex 631 . The first wave group 631 corresponds to low amplitude signals, and the second wave group 632 corresponds to high amplitude signals. Next, the time point of the trough between the first wave group 631 and the second wave group 632 in the envelope curve 610 is obtained as the reference end point 640 .

In some embodiments, the above-mentioned preset amplitude (dotted line 620) is determined according to the distance and the receiving angle between the acoustic wave receiving sensor and the acoustic wave emitting sensor. When the distance or the receiving angle is larger, the degree of decay of the sound wave is greater, so Decrease preset amplitude. In other words, the preset amplitude is inversely related to the aforementioned distance and receiving angle.

FIG. 7 is a flow chart illustrating a method for determining an ultrasonic time-of-flight according to an embodiment. Please refer to FIG. 7, in step 701, it is set that the first sound wave includes a low-amplitude signal and a high-amplitude signal, and the starting point of the high-amplitude signal is used as a reference starting point, wherein the high-amplitude signal follows the low-amplitude signal . In step 702, a first sound wave is emitted through the acoustic wave emitting sensor. In step 703, a second sound wave corresponding to the first sound wave is received through the sound wave receiving sensor. In step 704, the amplitude turning point in the second sound wave is judged, the amplitude turning point is taken as the reference end point, and the time difference between the reference start point and the reference end point is taken as the flight time of the sound wave. However, each step in FIG. 7 has been described in detail above, and will not be repeated here. It should be noted that each step in FIG. 7 can be implemented as a plurality of program codes or circuits, and the present invention is not limited thereto. In addition, the method in FIG. 7 can be used in conjunction with the above embodiments or can be used alone. In other words, other steps can also be added between the steps in FIG. 7 .

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention should be defined by the scope of the appended patent application.

100:Ultrasonic flight time judgment system 110: Calculation circuit UT1~UT12: Ultrasonic sensor 310: Low amplitude signal 320: High amplitude signal 330,340: signal 351: Reference starting point 352:Amplitude turning point 360: Sonic Time of Flight 401~406: Sound waves 510: dotted line 521,522: range 530,640: reference end point 610: Envelope curve 620: dotted line 631,632: waves 701~704: steps

FIG. 1 is a schematic diagram illustrating an ultrasonic time-of-flight judging system according to an embodiment. Fig. 2 is a schematic diagram of calculating the time-of-flight of sound waves according to an embodiment. FIG. 3 is a graph illustrating amplitude attenuation of sound waves at different angles according to an embodiment. FIG. 4 shows waveforms of second sound waves under different receiving angles according to an embodiment. FIG. 5 is a schematic diagram illustrating calculating an amplitude turning point when the receiving angle is smaller than a preset angle according to an embodiment. FIG. 6 is a schematic diagram illustrating calculating an amplitude turning point when the receiving angle is greater than or equal to a preset angle according to an embodiment. FIG. 7 is a flow chart illustrating a method for determining an ultrasonic time-of-flight according to an embodiment.

310: Low amplitude signal

320: High amplitude signal

330,340: signal

351: Reference starting point

352:Amplitude turning point

360: Sonic Time of Flight

Claims (10)

An ultrasonic time-of-flight judging system, comprising: an acoustic wave emitting sensor, configured to emit a first acoustic wave; the acoustic wave receiving sensor is used for receiving a second acoustic wave corresponding to the first acoustic wave; A calculation circuit, connected to the sound wave transmitting sensor and the sound wave receiving sensor, is used to set the first sound wave to include a low-amplitude signal and a high-amplitude signal, the high-amplitude signal follows the low-amplitude signal, and the The starting point of the high-amplitude signal is used as a reference starting point, Wherein the calculation circuit is used to judge an amplitude turning point in the second sound wave, the amplitude turning point is regarded as a reference end point, and the time difference between the reference starting point and the reference end point is regarded as sound wave flight time . The ultrasonic time-of-flight judging system as described in claim 1, wherein the calculation circuit obtains a receiving angle of the acoustic wave receiving sensor relative to the acoustic wave emitting sensor, When the receiving angle is smaller than a preset angle, the calculation circuit calculates the average value of the amplitude of the second sound wave, After calculating the average value, the calculation circuit judges whether the amplitude of the second sound wave exceeds the average value, and if so, judges whether the amplitude of the second sound wave shows an upward trend and remains stable, If the amplitude of the second sound wave exceeds the average value, shows an upward trend and remains stable, the calculation circuit obtains the time point when the amplitude of the second sound wave exceeds the average value for the first time as the reference termination point. The ultrasonic time-of-flight judging system as described in Claim 2, wherein the calculation circuit judges whether the slope of the amplitude of the second sound wave is positive at a plurality of consecutive sampling points to judge whether the amplitude of the second sound wave shows an upward trend, Wherein the calculating circuit judges whether the difference between the amplitude of the second sound wave before and after the sampling points is smaller than a preset value, so as to judge whether the second sound wave remains stable. The ultrasonic time-of-flight judging system as described in claim 3, wherein when the receiving angle is greater than or equal to the preset angle, the calculation circuit performs envelope processing on the second sound wave to obtain an envelope curve, The calculation circuit judges whether the envelope curve is greater than a preset amplitude to obtain a first wave group and a second wave group, wherein the first wave group and the second wave group are not connected, The calculation circuit obtains a time point of a trough between the first wave group and the second wave group as the reference termination point. The ultrasonic time-of-flight judging system according to claim 4, wherein the calculation circuit determines the preset amplitude according to the distance between the sound wave receiving sensor and the sound wave emitting sensor, wherein the distance is negatively correlated with the preset amplitude. A method for judging the time of flight of an ultrasonic wave is applicable to a computing circuit, and the method for judging the time of flight of an ultrasonic wave includes: setting a first sound wave to include a low-amplitude signal and a high-amplitude signal, the high-amplitude signal following the low-amplitude signal, and taking the starting point of the high-amplitude signal as a reference starting point; emitting the first sound wave through the acoustic wave emitting sensor; receiving a second sound wave corresponding to the first sound wave through the sound wave receiving sensor; and An amplitude inflection point in the second sound wave is judged, the amplitude inflection point is regarded as a reference end point, and the time difference between the reference start point and the reference end point is regarded as sound wave flight time. The method for judging the time of flight of ultrasonic waves as described in claim 6 further includes: obtaining a receiving angle of the acoustic wave receiving sensor relative to the acoustic wave emitting sensor; calculating an average value of the amplitude of the second sound wave when the receiving angle is smaller than a preset angle; After calculating the average value, determine whether the amplitude of the second sound wave exceeds the average value, and if so, determine whether the amplitude of the second sound wave shows an upward trend and remains stable; and If the amplitude of the second sound wave exceeds the average value, presents an upward trend and remains stable, the time point when the amplitude of the second sound wave exceeds the average value for the first time is taken as the reference termination point. The method for judging the time of flight of ultrasonic waves as described in claim 7 further includes: judging whether the slope of the amplitude of the second sound wave is positive at a plurality of consecutive sampling points to determine whether the amplitude of the second sound wave shows an upward trend; and It is judged whether the difference between the amplitude of the second sound wave before and after the sampling points is smaller than a preset value, so as to judge whether the second sound wave remains stable. The method for judging the time of flight of ultrasonic waves as described in claim 8 further includes: When the receiving angle is greater than or equal to the preset angle, performing envelope processing on the second sound wave to obtain an envelope curve; judging whether the envelope curve is greater than a predetermined amplitude to obtain a first wave group and a second wave group, wherein the first wave group is not connected to the second wave group; and A time point of a trough between the first wave group and the second wave group is obtained as the reference end point. The method for judging the time of flight of ultrasonic waves as described in claim 9 further includes: The preset amplitude is determined according to the distance between the sound wave receiving sensor and the sound wave emitting sensor, wherein the distance is negatively correlated with the preset amplitude.

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