Dynamic distance measurement method based on combination of large-view-field tracking and single-photon distance measurement

Abstract

The invention relates to the technical field of dynamic distance measurement, in particular to a dynamic distance measurement method based on combination of large-field-of-view tracking and single-photon distance measurement, which comprises the following steps: mounting a single-photon distance measurement system on photoelectric measurement equipment, and performing field-of-view alignment with the photoelectric measurement equipment; the method comprises the following steps: tracking a moving target through a large field of view of photoelectric measurement equipment, transmitting three kinds of laser pulses with different repetition frequencies to the moving target through a single-photon distance measurement system, carrying out distance measurement on the moving target, and collecting original triple-frequency distance measurement data formed by data points; preprocessing the original triple frequency ranging data to remove interference pulses; de-noising the pre-processed triple-frequency ranging data by adopting a threshold segmentation method based on local photon counting sum and local density statistical distribution; and calculating the distance of the moving target relative to the single-photon distance measurement system by using the de-noised triple-frequency distance measurement data. According to the invention, high-precision dynamic distance measurement of the moving target can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of dynamic ranging, and particularly relates to a dynamic ranging method based on the combination of large field of view tracking and single photon ranging. Background Art

[0002] With the rapid development of aerospace, military measurement and control, and unmanned aerial vehicle technologies, the demand for high-precision dynamic ranging of moving targets is increasing continuously. Traditional ranging technologies are restricted by factors such as environmental interference, rapid target movement, and signal attenuation, and it is difficult to achieve high-precision dynamic ranging under complex conditions. Single photon laser ranging technology is a high-sensitivity active detection technology, which has higher detection sensitivity, longer detection distance, and larger data sampling rate, and is widely used in fields such as long-distance target ranging, space debris monitoring, ground topography mapping, three-dimensional reconstruction imaging, and atmospheric parameter detection.

[0003] Considering the portability and mobility requirements of the single photon ranging system, the single photon ranging system is usually designed with a small aperture, resulting in a small field of view of the single photon ranging system, making it difficult to track moving targets and difficult to achieve dynamic ranging of moving targets. Summary of the Invention

[0004] In view of this, the present invention aims to provide a dynamic ranging method based on the combination of large field of view tracking and single photon ranging to solve the technical problem that the traditional single photon ranging system has limitations in tracking moving targets, resulting in difficulty in achieving dynamic ranging.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A dynamic ranging method based on the combination of large field of view tracking and single photon ranging, comprising the following steps: S1: Mount the single photon ranging system on the optoelectronic measurement equipment and align the field of view with the optoelectronic measurement equipment; S2: Track the moving target through the large field of view of the optoelectronic measurement equipment, and at the same time, emit laser pulses with three different repetition frequencies towards the moving target through the single photon ranging system to range the moving target, and collect the original triple-frequency ranging data composed of data points; S3: Preprocess the original triple-frequency ranging data to remove interference pulses; S4: Use a threshold segmentation method based on the sum of local photon counts combined with the local density statistical distribution to denoise the preprocessed triple-frequency ranging data; S5: Calculate the distance of the moving target relative to the single photon ranging system using the denoised triple-frequency ranging data.

[0006] Further, step S1 specifically includes the following steps: S11: Taking the edge of the reference target as a reference, adjust the optical axis of the single-photon ranging system. When the edge of the reference target is within the detection field of view of the single-photon ranging system and the number of echo photons is the largest, it is determined that the edge of the reference target is at the center of the detection field of view of the single-photon ranging system; S12: Using the same edge of the reference target, adjust the field of view of the visible light CCD camera so that the edge of the reference target is at the center of the detection field of view of the visible light CCD camera, and fix the adjusted visible light CCD camera to the single-photon ranging system; S13: Mount the single-photon ranging system with the fixed visible light CCD camera on the optoelectronic measurement equipment, and adjust the optical axis of the optoelectronic measurement equipment until the center of the detection field of view of the optoelectronic measurement equipment coincides with the center of the detection field of view of the visible light CCD camera, completing the alignment of the center of the detection field of view of the optoelectronic measurement equipment and the center of the detection field of view of the single-photon ranging system.

[0007] Further, step S3 specifically includes the following steps: S31: Identify the interference pulses in the original triple-frequency ranging data; among them, identify the signals with signal intensity greater than the threshold and not changing with time as interference pulses; S32: Eliminate the identified interference pulses from the original triple-frequency ranging data.

[0008] Further, in step S2, triple-frequency single-photon ranging is achieved by emitting three laser pulses with different repetition frequencies from the single-photon ranging system to the moving target.

[0009] Further, step S4 specifically includes the following steps: S41: Define a circular local window , and use this circular local window to traverse each data point , and calculate the total photon count within each data point and its circular local window ; the calculation formula for the total photon count is as follows:

[0010] where represents the set of data points within the circular local window centered on each data point , and represents the photon count of each data point ; S42: Count the frequency of the total photon count within the circular local window centered on each data point ​ , plot a histogram of the statistical distribution of the sum of local photon counts; S43: Divide the horizontal axis of the histogram of the statistical distribution of the sum of local photon counts into M equal-width intervals, and calculate the centroid position of the histogram of the statistical distribution of the sum of local photon counts after division ; The centroid position is calculated as follows:

[0011] where, k represents the central value of the interval, H ( k ) represents the frequency of occurrence of the sum of photon counts within each data point and its circular local window ; S44: Calculate the local density of the valid photon counts within each data point and its circular local window , count the frequency of the local density , plot a histogram of the statistical distribution of the local density and calculate the centroid position of the histogram of the statistical distribution of the local density; The calculation formula of the local density ; where, I represents the number of photon counts that meet the conditions within each data point and its circular local window ; S45: Take E times the centroid position and F times the centroid position as the segmentation threshold and the segmentation threshold respectively; where, , ; S46: Use the segmentation threshold and the segmentation threshold to segment all data points, and only retain the data points that and to obtain the denoised triple-frequency ranging data.

[0012] Furthermore, step S5 specifically includes the following steps: S51: Determine the signal fall times , , corresponding to the laser pulses with three different repetition frequencies, the following formula is used to calculate the distance of the moving target relative to the single photon ranging system measured by three laser pulses with different repetition frequencies: 、 、 :

[0013]

[0014]

[0015] in, 、 、 Represents the number of cycles corresponding to three laser pulses with different repetition frequencies, 、 、 Represent the cycle time corresponding to the repetition frequency of the three laser pulses, Indicates the propagation speed of laser in vacuum; S52: Calculation 、 、 The average value is taken as the final distance of the moving target relative to the single photon ranging system.

[0016] Furthermore, the repetition frequencies of the three laser pulses are 49 kHz, 49.5 kHz, and 50 kHz, respectively.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) Combining the high sensitivity of photoelectric measurement equipment for large field of view detection and the high sensitivity of single photon ranging system for long-distance detection, high-precision dynamic ranging of moving targets can be achieved.

[0018] (2) The threshold segmentation denoising method based on the sum of local photon counts combined with local density statistics has the characteristics of high computational efficiency, more robust noise processing, and can be used in extremely low signal-to-noise ratio scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 1 is a flow chart of a dynamic ranging method based on a combination of large field of view tracking and single photon ranging according to an embodiment of the present invention; Figure 2 2. It is a schematic diagram of the alignment between the detection field center and the edge of the reference target of the single-photon ranging system according to an embodiment of the present invention; Figure 3 3. This is a schematic diagram of the alignment of the detection field center of the visible light CCD camera and the detection field center of the single photon ranging system according to an embodiment of the present invention; Figure 4 Schematic diagram of the alignment of the detection field center of the optoelectronic measurement equipment and the detection field center of the single-photon ranging system according to an embodiment of the present invention; Figure 5a is a schematic diagram of original triple frequency ranging data containing interference pulses according to an embodiment of the present invention; Figure 5b 2. It is a schematic diagram of triple frequency ranging data after removing interference pulses according to an embodiment of the present invention; Figure 6 Schematic diagram of the setting and statistical rules of the circular local window according to the embodiment of the invention; Figure 7a 2. It is a schematic diagram of the statistical distribution of the total local photon count and the position of its centroid according to an embodiment of the present invention; Figure 7b Schematic diagram of the local density statistical distribution and its centroid position according to an embodiment of the present invention; Figure 8 2. It is a schematic diagram of triple frequency ranging data after threshold segmentation and noise removal according to an embodiment of the present invention; Figure 9 Schematic diagram of different distribution situations of triple frequency ranging signals according to an embodiment of the present invention; Figure 10 2 is a schematic diagram of the distance calculation result according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] The following will refer to Figures 1-10 The present invention is described in detail with reference to the embodiments.

[0025] like Figure 1 As shown, the present invention provides a dynamic ranging method based on the combination of large field of view tracking and single photon ranging, including the following steps: S1: Mount the single-photon ranging system on the optoelectronic measurement equipment and align the field of view with the optoelectronic measurement equipment.

[0026] Since the single-photon detector of the single-photon ranging system cannot form an image, a visible light CCD camera is required to align the field of view of the single-photon ranging system with the photoelectric measurement equipment. First, locate the center of the detection field of view of the single-photon ranging system, then locate the center of the field of view of the visible light CCD camera, and fix the located visible light CCD camera to the single-photon ranging system. Then, mount the single-photon ranging system with the visible light CCD camera on the photoelectric measurement equipment. Finally, adjust the field of view center of the photoelectric measurement equipment so that it aligns and overlaps with the field of view center of the visible light CCD camera. The large field of view alignment of the single-photon ranging system and the photoelectric measurement equipment is indirectly completed through the visible light CCD camera.

[0027] Step S1 specifically includes the following steps: S11: Taking the edge of the reference target as a reference, adjust the optical axis of the single-photon ranging system. When the edge of the reference target is within the detection field of view of the single-photon ranging system and the number of echo photons is the largest, it is determined that the edge of the reference target is at the center of the detection field of view of the single-photon ranging system.

[0028] Before step S11, the laser of the single-photon ranging system and the single-photon detector have been adjusted to be parallel, and it is default that the center of the laser spot coincides with the center of the detection field of view of the detector.

[0029] If the reference target fills the entire detection field of view of the single-photon ranging system, echo photons will fall back at each position of the reference target on the single-photon detector, and it is impossible to determine the center of the detection field of view of the single-photon ranging system based on the number of echo photons. However, when the edge of the reference target is within the detection field of view of the single-photon ranging system, it can be ensured that only the edge position of the reference target has echo photons falling back on the single-photon detector, and no echo photons will fall back at other positions of the reference target. In this way, the center of the detection field of view of the single-photon ranging system can be determined according to the number of echo photons.

[0030] During the process of aligning the center of the detection field of view of the single-photon ranging system with the edge of the reference target, adjust the optical axis of the single-photon ranging system. If the detection field of view deviates from the reference target, no echo photons will fall back on the single-photon detector. Continue to adjust the optical axis of the single-photon ranging system until echo photons appear on the single-photon detector, indicating that the edge position of the reference target is within the detection field of view of the single-photon ranging system. Then, adjust the optical axis of the single-photon ranging system until the number of echo photons is the largest. At this time, it is considered that the edge of the reference target is at the center of the detection field of view of the single-photon ranging system, and the alignment between the center of the detection field of view of the single-photon ranging system and the edge of the reference target is completed, as Figure 2 shown.

[0031] S12: Using the same edge of the reference target, adjust the field of view of the visible light CCD camera so that the edge of the reference target is at the center of the detection field of view of the visible light CCD camera, and fix the adjusted visible light CCD camera with the single-photon ranging system.

[0032] During the process of aligning the center of the detection field of view of the visible light CCD camera with the edge of the reference target, adjust the optical axis of the visible light CCD camera and take a picture of the reference target until the edge position of the reference target is at the center of the detection field of view of the visible light CCD camera, and the alignment between the center of the detection field of view of the visible light CCD camera and the edge of the reference target is completed, as Figure 3 shown.

[0033] S13: Mount the single-photon ranging system with the visible light CCD camera fixed on it onto the photoelectric measurement equipment, adjust the visual axis of the photoelectric measurement equipment until the detection field center of the photoelectric measurement equipment coincides with the detection field center of the visible light CCD camera, and complete the alignment of the detection field center of the photoelectric measurement equipment with the detection field center of the single-photon ranging system.

[0034] Taking the photoelectric theodolite as an example of photoelectric measurement equipment, the visual axis of the large-aperture infrared telescope of the photoelectric theodolite is adjusted. When the same edge of the reference target is in the center of the detection field of view of the large-aperture infrared telescope, the alignment of the detection field center of the large-aperture infrared telescope and the edge of the reference target is completed. At this time, the detection field center of the large-aperture infrared telescope, the detection field center of the visible light CCD camera, and the detection field center of the single-photon ranging system coincide with each other, such as Figure 4 shown.

[0035] S2: Track the moving target through the large field of view of the optoelectronic measurement equipment. At the same time, the single-photon ranging system emits three laser pulses with different repetition frequencies to the moving target to measure the distance of the moving target and collect the original triple-frequency ranging data consisting of data points.

[0036] S3: Preprocess the original triple frequency ranging data to remove interference pulses.

[0037] The purpose of preprocessing is to identify the interference pulses in the original triple frequency ranging data and remove them to reduce the difficulty of subsequent data processing. The interference pulse has the characteristics of higher signal intensity than the echo photon and does not change with time. The signal with this characteristic is regarded as the interference pulse. The interference pulse is usually located in front of the echo photon, such as Figure 5a and Figure 5b shown.

[0038] S4: The pre-processed triple frequency ranging data is de-noised using a threshold segmentation method based on the sum of local photon counts combined with local density statistical distribution.

[0039] Step S4 specifically includes the following steps: S41: Define a circular local window with a radius of 2 , using this circular local window Iterate over each data point , calculate for each data point and its circular partial window Total photon counts within the range .

[0040] The setting and statistical rules of the circular local window are as follows: Figure 6 As shown, each square represents a bin, and the number inside the square represents the photon count size at the data point.

[0041] All data points Composing a set of data points P : ; in, Represents each data point Returns the bin position of the time. Represents each data point Belongs to which frame data, Represents each data point The photon count is N, which represents the total number of all data points and the number of acquisition frames. K and the number of bins J Settings related, In the present invention, the bin width is set to 2 nanoseconds.

[0042] Total photon count The calculation formula is as follows:

[0043] in, Indicates that each data point A circular partial window centered on A collection of data points within a range.

[0044] S42: Statistics for each data point A circular partial window centered on The frequency of the total photon count within the range , plotted as a histogram of the statistical distribution of the total local photon counts.

[0045] The statistical distribution histogram of the total local photon count is approximately a one-sided normal distribution, such as Figure 7a shown.

[0046] S43: Divide the horizontal axis of the local photon count total statistical distribution histogram into M equal-width intervals, and calculate the centroid position of the divided local photon count total statistical distribution histogram .

[0047] The horizontal axis of the local photon count total statistical distribution histogram is divided into M equal-width intervals with an interval of 1, and the center value of the interval is k Represents the total photon count. Then the centroid position of the statistical distribution histogram of the total local photon count after division is calculated as follows: :

[0048] in, H ( k ) represents each data point and its circular local window The frequency of the sum of photon counts within the range. For example, if the sum of photon counts is 7, the number of times the sum of photon counts 7 appears is the frequency of the sum of photon counts 7.

[0049] The centroid position of the calculated statistical distribution histogram of the local photon count sum such as Figure 7a shown.

[0050] S44: Calculate the local density of the valid photon counts for each data point and its circular local window within the range, and count the frequency of the local density , plot it as a statistical distribution histogram of the local density, and calculate the centroid position of the statistical distribution histogram of the local density . . .

[0051] Local density The calculation formula is as follows: ; where I represents the number of photon counts that meet the conditions within the range of each data point and its circular local window . The statistical threshold is dynamically adjusted according to the strength of the signal photon count.

[0052] The statistical distribution histogram of the local density and its centroid position such as Figure 7b shown.

[0053] S45: Take 2.5 times the centroid position and 1.5 times the centroid position as the segmentation thresholds and segmentation threshold respectively; where , .

[0054] S46: Use the segmentation threshold and segmentation threshold to segment all data points, and only retain the data points that satisfy and to obtain the triple-frequency ranging data after denoising.

[0055] Based on the principle that the photon count at the signal location is generally greater than that at the noise location and the photon density at the signal location is greater than that at the noise location, retain the data points that satisfy and ​, the triple - frequency ranging data after denoising by threshold segmentation is obtained, as Figure 8 shown. The segmentation threshold and the size of the segmentation threshold can be dynamically adjusted according to the denoising effect.

[0056] The threshold segmentation denoising method based on the sum of local photon counts combined with local density statistics has the following advantages: 1) High computational efficiency: The statistics of photon numbers and the calculation of density have low complexity. Through sliding window or parallel computing, the computing resources can be fully utilized, which is suitable for real - time or large - scale data processing.

[0057] 2) More robust noise processing: By combining two features of photon count and effective count density, and dynamically adjusting the threshold according to the noise distribution, it has good processing effects for different noise distribution situations.

[0058] 3) Can be used in extremely low signal - to - noise ratio scenarios: Photon counting is sensitive to single - photon - level signals. Combining density statistics can suppress isolated noise points and utilize the signal continuity to enhance the extraction ability of extremely weak signals.

[0059] S5: Calculate the distance of the moving target relative to the single - photon ranging system using the denoised triple - frequency ranging data.

[0060] As shown in the following formula, for a single - photon ranging system that measures distance by the time - of - flight of photons, its maximum measurement distance is determined by the repetition frequency of the laser pulse:

[0061] represents the speed of light in vacuum; represents the refractive index of the laser with a given wavelength in the atmosphere; represents the repetition frequency of the laser pulse; represents the period time corresponding to the repetition frequency of the laser pulse.

[0062] If the measured distance of the moving target is greater than the system range, the echo photons cannot fall within this period, and the true distance of the moving target cannot be judged, resulting in range ambiguity in ranging. The present invention increases the ranging range by emitting three laser pulses with different repetition frequencies. The repetition frequencies of the three laser pulses are 49 kHz, 49.5 kHz, and 50 kHz respectively, and the maximum measurement distance is about 155 km. As Figure 9 shown, the ranging signal distribution is divided into three cases, and the signal fall - back moments , , After that, calculate the distances of the moving target measured by three laser pulses with different repetition frequencies relative to the single-photon ranging system according to the following formula , , :

[0063]

[0064]

[0065] wherein, , , respectively represent the number of cycles corresponding to three laser pulses with different repetition frequencies, , , respectively represent the cycle times corresponding to the repetition frequencies of three laser pulses.

[0066] Obtain the average values of , , as the final distance of the moving target relative to the single-photon ranging system, as shown in Figure 10 .

[0067] It should be understood that various forms of the flow shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. This is not limited herein.

[0068] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A dynamic ranging method based on the combination of large field of view tracking and single photon ranging, characterized in that, The steps include: S1: Mount the single photon ranging system on the optoelectronic measurement equipment and align the field of view with the optoelectronic measurement equipment; S2: Track the moving target through the large field of view of the optoelectronic measurement equipment. Simultaneously, the single-photon ranging system emits three laser pulses with different repetition frequencies to the moving target to measure the distance to the moving target and collect the original triple-frequency ranging data consisting of data points. S3: pre-processing the original triple frequency ranging data to remove interference pulses; S4: The pre-processed triple frequency ranging data is de-noised using a threshold segmentation method based on the sum of local photon counts combined with local density statistical distribution; S5: Calculate the distance of the moving target relative to the single photon ranging system using the denoised triple frequency ranging data.

2. The dynamic ranging method based on the combination of large field of view tracking and single photon ranging according to claim 1, wherein Step S1 specifically includes the following steps: S11: With the edge of the reference target as a reference, adjust the visual axis of the single photon ranging system. When the edge of the reference target is within the detection field of view of the single photon ranging system and the number of echo photons is the largest, it is determined that the edge of the reference target is within the center of the detection field of view of the single photon ranging system. S12: using the same edge of the reference target, adjusting the field of view of the visible light CCD camera so that the edge of the reference target is at the center of the detection field of view of the visible light CCD camera, and fixing the adjusted visible light CCD camera to the single photon ranging system; S13: Mount the single-photon ranging system with the visible light CCD camera fixed on it onto the photoelectric measurement equipment, adjust the visual axis of the photoelectric measurement equipment until the detection field center of the photoelectric measurement equipment coincides with the detection field center of the visible light CCD camera, and complete the alignment of the detection field center of the photoelectric measurement equipment with the detection field center of the single-photon ranging system.

3. The dynamic ranging method based on the combination of large field of view tracking and single photon ranging according to claim 1, characterized in that, Step S3 specifically includes the following steps: S31: Identify interference pulses in the original triple frequency ranging data; wherein, a signal whose signal strength is greater than a threshold and does not change with time is identified as an interference pulse; S32: Eliminate the identified interference pulse from the original triple frequency ranging data.

4. The dynamic ranging method based on the combination of large field of view tracking and single photon ranging according to claim 1, characterized in that In step S2, triple-frequency single-photon ranging is achieved by emitting three laser pulses with different repetition frequencies to a moving target through a single-photon ranging system.

5. The dynamic ranging method based on the combination of large field of view tracking and single photon ranging according to claim 4, characterized in that, Step S4 specifically includes the following steps: S41: Define a circular local window , and use this circular local window to traverse each data point , and calculate each data point and the sum of photon counts within its circular local window ; The calculation formula for the sum of photon counts is as follows: ​ Among them, represents a circular local window centered on each data point and is the set of data points within the range, represents the photon count of each data point ; S42: Count the frequency of the sum of photon counts within a circular local window centered on each data point and plot a histogram of the statistical distribution of the sum of local photon counts within the range ; S43: Divide the horizontal axis of the local photon count sum statistical distribution histogram into M equal-width intervals, and calculate the centroid position of the local photon count sum statistical distribution histogram after division ; Centroid position The calculation formula is as follows: Among them, k represents the central value of the interval, H ( k ) represents the frequency of occurrence of the total photon count within the range of each data point and its circular local window ; S44: Calculate each data point and its circular local window the local density of the effective photon count within the range , and count the local density frequency , plot it as a histogram of the local density statistical distribution and calculate the centroid position of the histogram of the local density statistical distribution ; Local density The calculation formula is as follows: Among them, I represents the number of photons satisfying the condition within each data point and its circular local window; S45: Respectively take E times the centroid position and F times the centroid position as the segmentation thresholds and the segmentation threshold ; where , ; S46: Use the segmentation threshold and the segmentation threshold to segment all the data points, and only retain and the data points to obtain the denoised triple-frequency ranging data.

6. The dynamic ranging method based on the combination of large field of view tracking and single photon ranging according to claim 1, characterized in that, Step S5 specifically includes the following steps: S51: Determine the signal fallback moments corresponding to laser pulses with three different repetition frequencies and and , and calculate the distances of the moving target measured by the laser pulses with three different repetition frequencies relative to the single-photon ranging system using the following formula and and : Among them, , , respectively represent the number of periods corresponding to three laser pulses with different repetition frequencies, , , respectively represent the period time corresponding to the repetition frequencies of three laser pulses, represents the propagation speed of light in vacuum; S52: Calculate , , The average value of is used as the distance of the final motion target relative to the single-photon ranging system.

7. The dynamic ranging method based on the combination of large field of view tracking and single photon ranging according to claim 1, characterized in that The repetition frequencies of the three laser pulses are 49kHz, 49.5kHz and 50kHz respectively.

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