A distance measurement system and a method for shielding fuzzy distance values

Abstract

The present invention provides a distance measurement system and a method for shielding fuzzy distance values. The distance measurement system includes: a transmitter, configured to emit a signal light beam with a pulse period of a first time toward an object to be measured; a collector, configured to collect part of the signal light beam reflected by the object to be measured and output a photon signal, wherein the effective working time of the collector is a second time, and the second time is less than the first time; a processing circuit, connected to the transmitter and the collector, the processing circuit calculates the target distance value of the object to be measured according to the photon signal, determines that the target distance value is a fuzzy distance value according to the photon signal and a resolution threshold, or according to the photon signal and a signal photon number threshold, and then shields the fuzzy distance value. The present invention realizes single-frequency ranging to solve the fuzzy ranging problem while also improving the measurement frame rate.

Description

Technical Field

[0001] The invention relates to the field of optical technology, in particular to a distance measurement system and a method for shielding fuzzy distance values. Background Art

[0002] For a distance measurement system based on the time-of-flight (TOF) principle, the distance calculation formula is: Where c is the speed of light, which is approximately 3×10 8 m / s, f is the modulation frequency of the emitted light signal, and k is a positive integer representing the number of integer cycles. If only one modulation frequency is used for distance measurement, the system usually defaults to k=0 in one measurement. When the reflected light signal collected by the collector comes from the target outside the maximum ranging range corresponding to the modulation frequency, it is impossible to confirm the actual distance of the target in which distance cycle, that is, the k value cannot be confirmed. The measured distance of the target is much smaller than the actual distance. This phenomenon is called the distance ambiguity phenomenon of TOF ranging. When the modulation frequency is f, the distance value corresponding to an integer number of cycles is called the fuzzy distance corresponding to the distance value at the current modulation frequency.

[0003] The existing methods to solve TOF distance ambiguity mainly include dual-frequency ranging to solve distance aliasing. Dual-frequency ranging is to use two different frequencies to measure the same target, and determine the true distance through the two measurement results. However, in the dual-frequency ranging method, the distance value of each target point needs to be measured twice in a row using two different frequencies, which will greatly reduce the measurement frame rate. The traditional TOF ranging method uses a single frequency to measure the distance, which will have the problem of ranging ambiguity. Therefore, how to solve the ranging ambiguity problem without reducing the system frame rate is an urgent problem to be solved. Summary of the invention

[0004] In order to overcome the problems existing in the prior art, an embodiment of the present invention provides a distance measurement system and a method for shielding fuzzy distance values ​​thereof.

[0005] To achieve the above-mentioned purpose, the technical solution of the embodiment of the present invention is implemented as follows: In a first aspect, an embodiment of the present invention provides a distance measurement system, including:

[0006] A transmitter configured to transmit a signal light beam having a pulse period of a first time toward the object to be detected;

[0007] A collector, configured to collect part of the signal light beam reflected by the object to be measured and output a photon signal, wherein the effective working time of the collector is a second time, and the second time is less than the first time;

[0008] A processing circuit is connected to the transmitter and the collector. The processing circuit calculates the target distance value of the object to be measured according to the photon signal. When the target distance value is determined to be a fuzzy distance value according to the photon signal and a resolution threshold, or according to the photon signal and a signal photon number threshold, the fuzzy distance value is shielded.

[0009] In some embodiments, the collector includes a pixel unit, the pixel unit includes a plurality of pixels, and the pixels are used to respond to a single photon in a portion of the signal light beam reflected back by the object to be measured and output the photon signal;

[0010] The collector further comprises a readout circuit, and the readout circuit is used to output a histogram according to the photon signal;

[0011] The processing circuit is also used to calculate the number of ambient photons and the number of signal photons based on the histogram; if the target distance value is determined to be a fuzzy distance value based on the number of ambient photons, the number of signal photons and a resolution threshold, or based on the number of signal photons and a preset signal photon number threshold, the fuzzy distance value is shielded.

[0012] In some embodiments, the resolution threshold comprises a preset quantitative resolution threshold or a variable resolution threshold; the variable resolution threshold is determined according to the average value of the ambient light illumination.

[0013] In some embodiments, the processing circuit calculates the target resolution of the object to be measured according to the number of signal photons and the number of ambient photons. If the target resolution is greater than the resolution threshold, or the target resolution is greater than or equal to the resolution threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded; or

[0014] If the processing circuit determines that the number of signal photons is less than the signal photon number threshold, or that the number of signal photons is less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0015] In some embodiments, the target resolution of the object to be measured is calculated according to the following first function model or second function model:

[0016] The first function model is:

[0017] The second function model is:

[0018] Among them, C s is the number of signal photons; C nis the number of ambient photons; a, b, c, d, e are all parameters; f represents the focal length of the collector lens; Resolution is the target resolution.

[0019] In some embodiments, the processing circuit determines a first ranging range and a second ranging range according to the first time and the second time; obtains a first resolution range corresponding to the first ranging range and a second resolution range corresponding to the second ranging range; and determines the preset quantitative resolution threshold according to the first resolution range and the second resolution range.

[0020] In some embodiments, the processing circuit calculates the mean ambient light illumination based on the signal photon number and the ambient photon number; determines the variable resolution threshold based on the mean ambient light illumination and a preset fitting function relationship, wherein the preset fitting function relationship includes the relationship between the variable resolution threshold and the mean ambient light illumination.

[0021] In some embodiments, the processing circuit obtains the number of signal photons and the number of ambient photons corresponding to different initial sampling points, and calculates the sampling resolution of each initial sampling point based on the number of signal photons and the number of ambient photons; if the sampling resolution of any initial sampling point is less than a preset sampling resolution threshold, or the sampling resolution is less than or equal to the preset sampling resolution threshold, the initial sampling point is marked as a target sampling point; and the average ambient light illumination is calculated based on the number of signal photons and the number of ambient photons at the target sampling point.

[0022] In some embodiments, the processing circuit calculates the reflectivity corresponding to each of the target sampling points according to the number of signal photons at each of the target sampling points and a pre-stored reflectivity calculation rule; calculates the sampling ambient light irradiance corresponding to each of the target sampling points according to the number of ambient photons at each of the target sampling points, the corresponding reflectivity, and a pre-stored ambient light irradiance calculation rule; calculates the sampling ambient light illumination corresponding to each of the target sampling points according to the sampling ambient light irradiance corresponding to each of the target sampling points, and calculates the ambient light illumination mean according to the sampling ambient light illumination corresponding to each of the target sampling points.

[0023] In some embodiments, the pre-stored reflectivity calculation rule is:

[0024]

[0025] Where Re is the reflectivity of the object under test at any target sampling point; C ns is the number of signal photons at the target sampling point; TCSPC is the number of pulses emitted in a priori single-frame measurement; θ is the incident angle of light; L is the measurement distance of the object being measured; P tis the peak power of the signal light beam emitted by the light source; k1 is the first preset coefficient.

[0026] In some embodiments, the pre-stored calculation rule of ambient light irradiance is:

[0027]

[0028] Among them, I AL is the ambient light irradiance at any target sampling point; C ns is the number of signal photons at the target sampling point; C nn is the number of ambient photons at the target sampling point; θ is the incident angle of light; L is the measurement distance of the object to be measured; f represents the focal length of the collector lens; k2 is the second preset coefficient, and k3 is the third preset coefficient.

[0029] In a second aspect, an embodiment of the present invention provides a method for shielding a fuzzy distance value, comprising:

[0030] Acquire a photon signal corresponding to a signal light beam reflected by the object to be measured; wherein the emission pulse period of the signal light beam is a first time, the effective acquisition time of the signal light beam is a second time, and the second time is less than the first time;

[0031] Calculate the target distance value of the object to be measured according to the photon signal;

[0032] When the target distance value is determined to be a fuzzy distance value according to the photon signal and the resolution threshold, or according to the photon signal and the signal photon number threshold, the fuzzy distance value is shielded.

[0033] In some embodiments, when the target distance value is determined as a fuzzy distance value according to the photon signal and the resolution threshold, or according to the photon signal and the signal photon number threshold, the fuzzy distance value is shielded, including:

[0034] Acquiring the number of signal photons and the number of ambient photons; the number of signal photons and the number of ambient photons are determined according to the photon signal;

[0035] If the target distance value is determined to be a fuzzy distance value based on the number of ambient photons, the number of signal photons and a resolution threshold, or based on the number of signal photons and a preset signal photon number threshold, the fuzzy distance value is shielded.

[0036] In some embodiments, if the target distance value is determined to be a fuzzy distance value according to the number of ambient photons, the number of signal photons and a resolution threshold, or according to the number of signal photons and a preset signal photon number threshold, then shielding the fuzzy distance value includes:

[0037] Calculate the target resolution of the object to be measured according to the signal photon number and the ambient photon number; if the target resolution is greater than a resolution threshold, or the target resolution is greater than or equal to the resolution threshold, determine the target distance value as a fuzzy distance value, and shield the fuzzy distance value; or,

[0038] If it is determined that the number of signal photons is less than the signal photon number threshold, or the number of signal photons is less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0039] In some embodiments, the resolution threshold comprises a preset quantitative resolution threshold or a variable resolution threshold; the variable resolution threshold is determined according to the average value of the ambient light illumination.

[0040] Compared with the prior art, the present invention shields the fuzzy ranging value of the ranging system based on the resolution threshold or the signal photon number threshold, realizes single-frequency ranging to solve the ranging ambiguity and improves the measurement frame rate at the same time.

[0041] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

[0042] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of a distance measurement system according to an exemplary embodiment of the present invention;

[0044] Figure 2 A schematic flow chart of a method for shielding fuzzy distance values ​​in a distance measurement system according to an exemplary embodiment of the present invention;

[0045] Figure 3 A schematic diagram of the structure of a device for shielding fuzzy distance values ​​is shown as an exemplary embodiment of the present invention;

[0046] Figure 4 is a schematic diagram of a device for shielding fuzzy distance values ​​provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0047] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0048] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0049] Figure 1 The figure shows a schematic diagram of a distance measurement system provided by an exemplary embodiment, and the distance measurement system 10 includes a transmitter 11, a collector 12, and a processing circuit 13. The transmitter 11 is used to transmit a light beam 300 to a target area 200, and the light beam is transmitted to the target area space to illuminate the target object in the space. At least part of the transmitted light beam 300 is reflected by the target area 200 to form a reflected light beam 400, and at least part of the reflected light beam 400 is received by the collector 12; the processing circuit 13 is connected to the transmitter 11 and the collector 12 respectively, and the trigger signals of the transmitter 11 and the collector 12 are synchronized to calculate the time required for the light beam to be received from the emission to the reflection, that is, the flight time t between the emitted light beam 300 and the reflected light beam 400. Further, the distance D of the corresponding point on the target object can be calculated by the following formula:

[0050] D=c·t / 2

[0051] Where c is the speed of light.

[0052] Specifically, the transmitter 11 includes a light source 111, an emitting optical element 112, and a driver 113. Among them, the light source 111 can be a light emitting diode (LED), a laser diode (LD), an edge emitting laser (EEL), a vertical cavity surface emitting laser (VCSEL), etc., or a one-dimensional or two-dimensional light source array composed of multiple light sources; preferably, the light source array is a VCSEL array light source chip formed by generating multiple VCSEL light sources on a single semiconductor substrate, and the arrangement of the light sources in the light source array can be regular or irregular. The light beam emitted by the light source 111 can be visible light, infrared light, ultraviolet light, etc. The light source 111 emits a light beam outward under the control of the driver 113. In one embodiment, the light source 111 emits a pulsed light beam outward at a certain frequency (pulse period) under the control of the driver 113, which can be used in direct time of flight (Direct TOF) measurement, and the frequency is set according to the measurement distance. It can be understood that a part of the processing circuit 13 or a subcircuit that exists independently of the processing circuit 13 can also be used to control the light source 111 to emit a light beam.

[0053] The emission optical element 112 receives the light beam emitted from the light source 111 and shapes it to project it to the target area. In one embodiment, the emission optical element 112 receives the pulse light beam from the light source 111, and optically modulates the pulse light beam, such as diffraction, refraction, reflection, etc., and then emits the modulated light beam into space, such as a focused light beam, a flood light beam, a structured light beam, etc. The emission optical element 112 can be a combination of one or more of the forms of a lens, a liquid crystal element, a diffractive optical element, a microlens array, a metasurface optical element, a mask plate, a reflector, a MEMS galvanometer, etc.

[0054] The collector 12 includes a pixel unit 121, a filter unit 122 and a receiving optical element 123; wherein the receiving optical element 123 is used to receive at least part of the light beam reflected by the target and guide it to the pixel unit 121; the filter unit 122 is used to filter out background light or stray light. The pixel unit 121 includes a two-dimensional pixel array composed of a plurality of pixels. In one embodiment, the pixel unit 121 is a pixel array composed of single-photon avalanche photodiodes (SPADs), which can respond to incident single photons and output signals indicating the corresponding arrival time of the received photons at each SPAD, and use methods such as time-correlated single-photon counting (TCSPC) to collect weak light signals and calculate flight time. Generally, a readout circuit (not shown in the figure) composed of one or more devices such as a signal amplifier, a time-to-digital converter (TDC), and a digital-to-analog converter (ADC) is also connected to the pixel unit 121. These circuits can be integrated with the pixel unit 121 as part of the collector 12, or as part of the processing circuit 13.

[0055] The processing circuit 13 synchronizes the trigger signals of the emitter 11 and the collector 12, processes the photon signal of the pixel collection light beam, and calculates the distance information of the target object to be measured based on the flight time of the reflected light beam. In one embodiment, the SPAD responds to the incident single photon and outputs a photon signal, and the processing circuit 13 receives the photon signal and performs signal processing to obtain the flight time of the light beam.

[0056] Specifically, the processing circuit 13 counts the number of collected photons to form continuous time bins (recorded as the unit time of the collector sampling). These time bins are connected together to form a statistical histogram to reproduce the time series of the reflected light beam, and use peak matching and filtering detection to identify the flight time of the reflected light beam from emission to reception.

[0057] In an embodiment of the present invention, the transmitter is configured to transmit a signal light beam with a pulse period of a first time toward the object to be measured; the collector is configured to collect part of the signal light beam reflected back by the object to be measured and output a photon signal, wherein the effective working time of the collector is a second time, and the second time is less than the first time;

[0058] The processing circuit is connected to the transmitter and the collector, calculates the target distance value of the object to be measured according to the electrical signal, determines whether the target distance value is a fuzzy distance value according to the target distance value and a preset threshold, and shields the fuzzy distance value.

[0059] The preset threshold is pre-stored in the distance measurement system, and the preset threshold may be a resolution threshold or a signal photon number threshold, which is not limited here. The processing circuit determines whether the target distance value is a fuzzy distance value according to the target distance value and the preset threshold, and if the target distance value is a fuzzy distance value, the fuzzy distance value is shielded.

[0060] In some embodiments, the collector includes a readout circuit, which includes a TDC circuit and a histogram circuit, wherein the TDC circuit is used to receive and calculate the flight time information of the photon, and convert the flight time information into a time code; the time code is input into the histogram circuit to address the corresponding time bin (recorded as the unit time of the collector sampling), and the photon count value in the corresponding time bin is increased. After a frame of measurement is completed, a statistical histogram is drawn according to the photon count values ​​in all time bins, and the statistical histogram includes continuous time intervals (time bins). The horizontal axis of the histogram represents the flight time, and the vertical axis represents the photon count value. The photon count value in each time interval includes ambient photons and / or signal photons. The processing circuit calculates the number of ambient photons and the number of signal photons according to the histogram output by the histogram circuit; wherein the number of signal photons is the sampling signal, which is the number of photons in the signal beam reflected by the object to be measured collected by the collector, and the number of ambient photons is the environmental data, which is the number of ambient photons collected by the collector when collecting photons in the signal beam reflected by the object to be measured. Specifically, firstly, a local area is intercepted from the histogram to calculate the mean number of ambient photons, and then a local area away from the pulse peak position is selected according to the pulse peak position in the histogram to calculate the mean number of ambient photons. In an optional embodiment, the mean number of ambient photons can also be calculated according to all the time intervals of the histogram, and the sum of the number of photons in all the time intervals is removed from the sum of the number of photons at the pulse peak position and then the average is calculated to obtain the mean number of ambient photons, and the mean number of ambient photons is the number of ambient photons included in each time interval in the histogram. Furthermore, according to the pulse peak position and the pulse width, a pulse area is intercepted from the histogram to calculate the sum of the number of photons in the area and the number of ambient photons, and the number of signal photons is further calculated. In some other embodiments, other methods can also be used to calculate the number of ambient photons and the number of signal photons, which are not specifically limited in the present invention.

[0061] Assuming that the maximum measurement range of the distance measurement system is D, the pulse period is usually set to time T, T = 2D / c. When designing the system, the working time of the TDC circuit corresponds to T, and the number of time bins configured in the histogram circuit is designed according to T. In an embodiment of the present invention, the pulse period of the modulated emission light pulse is the first time T1, and the collector is modulated to collect the reflected light signal within a second time T2 that is less than the first time T1. In the time period of T1-T2, the TDC circuit is in a reset state and no longer counts, then the effective working time of the collector is the second time T2, and the effective working time of the TDC is also the second time T2, then the number of time bins configured in the histogram circuit is designed according to the second time T2.

[0062] Take T1=125ns as an example. Assuming T1=125ns, the corresponding ranging range is 18.75m, and T2=66.66ns, the corresponding ranging range is 10m. Then, for targets between 10m and 18.75m, the collector cannot collect reflected light signals. If the target is between 18.75m and 28.75m and the reflected light signal can be collected by the collector, distance ambiguity may occur, that is, the distance value measured by the ranging system is still within the range of 0 to 10m.

[0063] When the pulse period is set to T1 = 125 ns, the number of time-correlated single-photon counting (TCSPC) is determined as:

[0064]

[0065] The total number of TCSPCs is approximately 64,000.

[0066] In order to improve the signal-to-noise ratio, in one embodiment, n pulses can be emitted in each pulse period to form a pulse train, and the intervals between the pulses are randomly configured, for example, can be set to t1, t2, ...tn, and t1+t2+...+tn=T1, the equivalent TCSPC number is 64000*n, n is the number of pulse beams in one period.

[0067] In an optional embodiment, a preset quantitative resolution threshold can be used to determine whether the object to be measured is within the distance measurement range. Specifically, the system obtains the number of signal photons and the number of ambient photons, and then calculates the target resolution of the object to be measured based on the number of signal photons and the number of ambient photons; if the target resolution is greater than, or greater than or equal to the preset quantitative resolution threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0068] In one embodiment, the preset quantitative resolution threshold may be preset in the following manner.

[0069] Among them, the emission pulse period of the signal light beam is the first time; the effective collection time of the signal light beam is the second time; the second time is less than the first time; the first ranging range and the second ranging range are determined according to the first time and the second time; the first resolution range corresponding to the first ranging range and the second resolution range corresponding to the second ranging range are obtained; and the preset quantitative resolution threshold is determined according to the first resolution range and the second resolution range.

[0070] Specifically, for the distance ambiguity problem, taking T1 = 125ns as an example, since the distance measurement range corresponding to the modulation pulse period is 18.75m, and the collector is controlled to only receive the reflected light signal within the first 10m of the target, the next period of the next distance ambiguity signal will correspond to a distance range of 18.75 to 28.75m.

[0071] In order to avoid the ranging signal of 18.75 to 28.75m in the next cycle interfering with the ranging accuracy of normal 0 to 10m, the resolution distribution under different peak power, incident angle, ambient light and reflectivity when the object to be measured is respectively located in the first ranging range of 0 to 10m and the second ranging range of 18.75 to 28.75m is measured, and the resolution within the first ranging range of 0 to 10m and the second ranging range of 18.75 to 28.75m is compared. Among them, for the object to be measured at a certain preset distance, it is necessary to measure n times continuously and calculate the variance of the n distance values ​​as the resolution, and adjust the peak power, incident angle, ambient light, reflectivity and other parameters differently, repeat the above sampling process to obtain multiple groups of calibration data. It can be understood that only one of the influencing parameters can be adjusted or multiple parameters can be adjusted at the same time, the size of the parameter can be randomly adjusted using the mode of generating random numbers, or the size of the parameter can be adjusted according to a certain rule, such as according to the adjustment mode from small to large or from large to small, and the specific adjustment method is not limited in this application.

[0072] When the measured object has different reflectivity and the ambient light intensity is different, there is a large gap in the resolution of the two ranging ranges of 0 to 10m and 18.75 to 28.75m, and as the ambient light increases, the overlapping resolution in the two ranges becomes smaller and smaller. Through a large amount of measurement data fitting, it is determined that the resolution distribution in the range of 0 to 10m is the first resolution range [0, R1], and the resolution distribution in the range of 18.75 to 28.75m is the second resolution range [R2, R3], and R2≤R1, so a fixed value R can be selected as the resolution threshold to shield the ranging ambiguity, and R is usually set to a fixed value less than R2.

[0073] During actual measurement, the system calculates the real-time target resolution and compares the target resolution with the preset quantitative resolution threshold to shield the fuzzy distance value. Specifically, the distance measurement system calculates the number of ambient photons and the number of signal photons according to the histogram output by the histogram circuit, and calculates the target resolution according to the number of ambient photons, the number of signal photons and the preset resolution calculation rules. The system pre-stores the preset resolution calculation rules, that is, the corresponding relationship between the number of ambient photons, the number of signal photons and the resolution, and calculates the target resolution according to the pre-stored resolution calculation rules.

[0074] In the embodiment of the present invention, there is no specific limitation on the preset resolution calculation rule. When the preset resolution calculation rule is a function model, it can be a function model in various forms. For example, the preset resolution calculation rule can be the following function model:

[0075]

[0076] Among them, C s is the number of signal photons; C n is the number of ambient photons; a, b, c, d are all parameters; Resolution is the resolution.

[0077] For another example, the preset resolution calculation rule may also be the following function model:

[0078]

[0079] Among them, C s is the number of signal photons; C n is the number of ambient photons; a, b, c, d, e are all parameters; f represents the focal length of the collector lens.

[0080] In order to accurately obtain the calculation result of the resolution, the function model of the preset resolution calculation rule can be obtained by fitting or training the sampling data.

[0081] The system determines the size between the target resolution and the preset quantitative resolution threshold. If the target resolution is greater than, or greater than or equal to the preset quantitative resolution threshold, the target distance value is determined to be a fuzzy distance value and the fuzzy distance value is shielded. During the ranging process, the real-time target resolution R4 is calculated based on the real-time signal photon number and the ambient photon number. If R4>R, it indicates that the target distance value is a fuzzy distance value and needs to be shielded.

[0082] Although the method of preset quantitative resolution shielding solves the ranging ambiguity, the ranging range sacrificed is too large, especially in the case of long distance, high ambient light and low reflectivity, the ranging range is greatly reduced.

[0083] In an optional embodiment, in order to overcome the distance measurement ambiguity without sacrificing too much distance measurement range, a variable resolution threshold can be determined to determine whether the object to be measured is within the distance measurement range, wherein the variable resolution threshold is determined according to the real-time average value of ambient light illumination. The device can obtain the number of signal photons and the number of ambient photons; calculate the target resolution of the object to be measured according to the number of signal photons and the number of ambient photons; calculate the average value of ambient light illumination according to the number of ambient photons and the number of signal photons; determine the variable resolution threshold according to the calculated average value of ambient light illumination and the fitting function relationship between the preset variable resolution threshold and the average value of ambient light illumination; if the target resolution is greater than, or greater than or equal to the determined variable resolution threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0084] Specifically, the system obtains the number of signal photons and the number of ambient photons, and calculates the target resolution of the object to be measured based on the number of signal photons and the number of ambient photons. The specific details can be referred to the detailed description above and will not be repeated here.

[0085] The system obtains the number of signal photons and the number of ambient photons corresponding to different initial sampling points, and calculates the sampling resolution of each initial sampling point according to the number of signal photons and the number of ambient photons; if the sampling resolution is less than the preset sampling resolution threshold, or the sampling resolution is less than or equal to the preset sampling resolution threshold, the initial sampling point is marked as a target sampling point. In other words, the initial sampling points with a sampling resolution greater than, or greater than or equal to the preset sampling resolution threshold are shielded, and the remaining initial sampling points are marked as target sampling points.

[0086] Then, the mean value of the ambient light illumination is calculated according to the number of signal photons and the number of ambient photons at the target sampling point; finally, the variable resolution threshold is determined according to the calculated mean value of the ambient light illumination, the fitting function relationship between the preset variable resolution threshold and the mean value of the ambient light illumination.

[0087] The sampling resolution of each initial sampling point can be calculated according to the preset resolution calculation rule provided above; the preset sampling resolution threshold can be set with reference to the setting method of the preset quantitative resolution threshold above, which will not be repeated here. The target sampling point is the sampling point that meets the preset quantitative resolution threshold constraint.

[0088] When calculating the mean value of ambient light illumination according to the number of signal photons and the number of ambient photons at the target sampling point, first calculate the reflectivity corresponding to each target sampling point according to the number of signal photons at each target sampling point and a pre-stored reflectivity calculation rule; then, calculate the sampled ambient light irradiance corresponding to each target sampling point according to the number of ambient photons at each target sampling point, the corresponding reflectivity, and the pre-stored ambient light irradiance calculation rule; finally, calculate the sampled ambient light irradiance corresponding to each target sampling point according to the sampled ambient light irradiance corresponding to each target sampling point, and calculate the mean value of ambient light irradiance according to the sampled ambient light irradiance corresponding to each target sampling point.

[0089] In some embodiments, a reflectivity calculation rule is pre-stored in the system, that is, the correspondence between the number of signal photons and the reflectivity, and the reflectivity of the object to be measured is calculated based on the correspondence between the number of signal photons and the reflectivity.

[0090] Among them, the corresponding relationship between the number of signal photons and the reflectivity is obtained by deduction. In addition to being affected by the reflectivity of the object being measured, the number of signal photons collected by the collector will also be affected by the number of pulses emitted in a single frame measurement, the incident angle of light, the measurement distance of the object being measured, the peak power of the signal beam emitted by the light source, and other factors. Therefore, the corresponding relationship between the number of signal photons and the reflectivity is calibrated when other factors are fixed, that is, the calculation rule of the reflectivity is derived.

[0091] When calculating the reflectivity, the system first obtains the known information such as the number of pulses emitted in a single frame measurement, the incident angle of light, the measurement distance of the object to be measured, the peak power of the signal beam emitted by the light source, etc., and calculates the reflectivity of the object to be measured based on the determined parameters and the pre-stored reflectivity calculation rules.

[0092] In an optional embodiment, the pre-stored reflectivity calculation rule may be:

[0093]

[0094] Where Re is the reflectivity of the object under test at any target sampling point; C ns is the number of signal photons at the target sampling point; TCSPC is the number of pulses emitted in a priori single-frame measurement; θ is the incident angle of light; L is the measurement distance of the object being measured; P t is the peak power of the signal beam emitted by the light source; k1 is the first preset coefficient, which is a constant determined according to the design of the system. For different system designs, the constant k1 will change.

[0095] According to the above pre-stored reflectivity calculation rules, the reflectivity corresponding to each target sampling point can be calculated respectively. It can be understood that the correspondence between the number of signal photons and the reflectivity is not limited to the above relationship, and the above relationship does not specifically limit the correspondence between the number of signal photons and the reflectivity.

[0096] In some embodiments, the system can calculate the sampled ambient light irradiance based on the number of ambient photons, the number of signal photons, the focal length of the collector lens, the light incident angle, the reflectivity, and a pre-stored ambient light irradiance calculation rule.

[0097] In an optional embodiment, the pre-stored ambient light irradiance calculation rule is:

[0098]

[0099] Among them, I AL is the ambient light irradiance at any target sampling point; C ns is the number of signal photons at the target sampling point; C nn is the number of ambient photons at the target sampling point; θ is the incident angle of light; L is the measurement distance; f represents the focal length of the collector lens; k2 is the second preset coefficient, k3 is the third preset coefficient, the second preset coefficient and the third preset coefficient are constants determined according to the design of the system, and this constant will change for different system designs.

[0100] According to the above-mentioned pre-stored ambient light irradiance calculation rules, the sampled ambient light irradiance calculation rules corresponding to each target sampling point can be calculated respectively. It can be understood that the pre-stored ambient light irradiance calculation rules are not limited to the above-mentioned relationship, and the above-mentioned relationship does not specifically limit the pre-stored ambient light irradiance calculation rules.

[0101] In some embodiments, the system first calculates the sampling ambient light illumination corresponding to each target sampling point according to the sampling ambient light irradiance corresponding to each target sampling point, and then averages the sampling ambient light illumination corresponding to each target sampling point to obtain the ambient light illumination mean.

[0102] In an optional embodiment, the sampling ambient light irradiance of each target sampling point is first calculated according to the calculated sampling ambient light irradiance, and the following formula may be used specifically:

[0103]

[0104] Among them, E i is the sampled ambient light intensity at the target sampling point i, I AL is the sampled ambient light irradiance of the target sampling point i, i is the number of the target sampling point, i = 1, 2, 3...n. n is the total number of target sampling points.

[0105] Then, the average of the sampled ambient light illumination values ​​of multiple n target sampling points that meet the preset quantitative resolution threshold constraint is calculated to obtain the ambient light illumination mean value E:

[0106]

[0107] It should be noted that, in this embodiment, the target sampling points are numbered sequentially, but it should be understood that sequential numbering may not be used in other embodiments.

[0108] In some embodiments, the fitting function relationship between the variable resolution threshold and the mean value of the ambient light illumination may be specifically set in the following manner.

[0109] The linear function relationship between the resolution threshold and the mean ambient light illumination is: Resolution = aE + b. The resolution threshold for shielding distance blur under different ambient light conditions is obtained to obtain calibration data of multiple sets of ambient light illumination mean and resolution threshold. The size of coefficients a and b is determined according to the calibration data. In actual distance measurement, the real-time variable resolution threshold Resolution can be determined according to the calculated ambient light illumination mean E.

[0110] In an optional embodiment, in order to avoid sacrificing the ranging range, a signal photon number threshold can be used to shield the ranging ambiguity. The system obtains the real-time signal photon number. If the signal photon number is less than, or less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value and the fuzzy distance value is shielded.

[0111] Specifically, for the distance ambiguity problem, since the distance measurement range corresponding to the modulation pulse cycle is 18.75m, and the collector is controlled to only receive the reflected light signal within the first 10m of the target, the next cycle of the next distance ambiguity signal will correspond to the distance range of 18.75 to 28.75m.

[0112] In order to avoid the ranging signal of 18.75 to 28.75m in the next cycle interfering with the normal ranging accuracy of 0 to 10m, the resolution distribution under different peak power, incident angle, ambient light, and reflectivity is measured when the object to be measured is located in the first ranging range of 0 to 10m and the second ranging range of 18.75 to 28.75m, wherein, for the object to be measured at a certain preset distance, it is necessary to continuously measure n times to calculate the variance of the distance value as the resolution, and adjust the parameters such as peak power, incident angle, ambient light, and reflectivity differently. The parameters such as incident angle, ambient light illumination or reflectivity can be adjusted, and the above sampling process is repeated to obtain multiple sets of calibration data. At the same time, the signal photon number thresholds in the range of 0 to 10m and 18.75m to 28.75m can be determined. Since the signal photon number is inversely proportional to the square of the distance, the minimum signal photon number in the range of 0 to 10m can be determined according to the calibrated data and set as the signal photon number threshold. When the number of signal photons monitored in real time is less than the signal photon number threshold, the ranging value is invalid.

[0113] See also Figure 2 , Figure 2 The flowchart of a method for shielding fuzzy distance values ​​is shown as an exemplary embodiment of the present invention. The method comprises the following steps:

[0114] S201: Acquire a photon signal corresponding to a signal light beam reflected by the object to be measured;

[0115] In the embodiment of the present invention, a signal light beam is emitted by a transmitter, and a reflected light signal is reflected back by the object to be measured to be received by a collector, and a photon signal is output. The emission pulse period of the signal light beam is the first time (i.e., the pulse period of the signal light beam emitted by the transmitter is the first time), and the effective collection time of the signal light beam is the second time (the effective working time of the collector); the second time is less than the first time.

[0116] S202: Calculating a target distance value of the object to be measured according to the photon signal;

[0117] In the embodiment of the present invention, according to the histogram output by the histogram circuit, the flight time of the signal light beam from emission to reflection back to reception is identified by using peak matching and filtering detection, so as to calculate the target distance of the object to be measured.

[0118] S203: If the target distance value is determined to be a fuzzy distance value according to the photon signal and the resolution threshold, or according to the photon signal and the signal photon number threshold, shielding the fuzzy distance value;

[0119] In the embodiment of the present invention, the resolution threshold may include a preset quantitative resolution threshold or a variable resolution threshold.

[0120] In an optional embodiment, a preset quantitative resolution threshold is used to determine whether the object to be measured is within the ranging range. First, the number of signal photons and the number of ambient photons are obtained, and then the target resolution of the object to be measured is calculated based on the number of signal photons and the number of ambient photons. If the target resolution is greater than, or greater than or equal to the preset quantitative resolution threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0121] In an optional embodiment, a preset variable resolution threshold is used to determine whether the object to be measured is within the ranging range. First, the number of signal photons and the number of ambient photons are obtained, and then the target resolution of the object to be measured is calculated based on the number of signal photons and the number of ambient photons. If the target resolution is greater than, or greater than or equal to the preset variable resolution threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0122] In an optional embodiment, the distance measurement ambiguity is shielded by using a signal photon number threshold to obtain the signal photon number. If the signal photon number is less than, or less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0123] It should be noted that, in some embodiments, the method for shielding fuzzy distance values ​​provided in the embodiments of the present invention can be implemented by using any of the distance measurement systems in the aforementioned embodiments. For specific details, please refer to the description in the distance measurement system embodiment, which will not be repeated here.

[0124] Compared with the prior art, the embodiments of the present invention obtain an electrical signal corresponding to a signal light beam reflected by an object to be measured; calculate a target distance value of the object to be measured according to the electrical signal; if the target distance value is determined to be a fuzzy distance value according to the target distance value and a preset threshold, the fuzzy distance value is shielded. The present invention solves the problem of shielding the fuzzy distance value of the ranging system based on the preset threshold, realizes single-frequency ranging and resolves distance aliasing without reducing the measurement frame rate.

[0125] See also Figure 3 , Figure 3 The schematic diagram of the structure of the device for shielding the fuzzy distance value of the distance measurement system is shown as an exemplary embodiment of the present invention. The units included are used to execute Figure 2 For details of the steps in the corresponding embodiments, please refer to Figure 2 For the convenience of explanation, only the parts related to this embodiment are shown. Figure 3 , the device 3 for shielding the fuzzy distance value of the distance measurement system comprises:

[0126] An acquisition unit 310 is used to acquire a photon signal corresponding to a signal light beam reflected by the object to be measured;

[0127] A calculation unit 320, configured to calculate a target distance value of the object to be measured according to the photon signal;

[0128] The processing unit 330 is configured to shield the fuzzy distance value if it is determined that the target distance value is a fuzzy distance value based on the photon signal and the resolution threshold, or based on the photon signal and the signal photon number threshold.

[0129] Furthermore, the processing unit 330 is specifically configured to:

[0130] Acquiring the number of signal photons and the number of ambient photons; the number of signal photons and the number of ambient photons are determined according to the photon signal;

[0131] The target distance value is determined to be a fuzzy distance value according to the number of ambient photons, the number of signal photons and a resolution threshold, or according to the number of signal photons and a preset signal photon number threshold, and the fuzzy distance value is shielded.

[0132] Further, the emission pulse period of the signal light beam is a first time; the effective collection time of the signal light beam is a second time; the second time is shorter than the first time;

[0133] Furthermore, the processing unit 330 is specifically configured to:

[0134] Calculate the target resolution of the object to be measured according to the signal photon number and the ambient photon number; if the target resolution is greater than a resolution threshold, or the target resolution is greater than or equal to the resolution threshold, determine the target distance value as a fuzzy distance value, and shield the fuzzy distance value; or,

[0135] If it is determined that the number of signal photons is less than the signal photon number threshold, or the number of signal photons is less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

[0136] See also Figure 4 , Figure 4 FIG. 1 is a schematic diagram of a device for shielding fuzzy distance values ​​provided by an exemplary embodiment of the present invention. Figure 4 As shown, the device 4 for shielding fuzzy distance values ​​in this embodiment includes: a processor 40, a memory 41, and a computer program 42 stored in the memory 41 and executable on the processor 40, such as a shielding program for fuzzy distance values. When the processor 40 executes the computer program 42, the steps in the above-mentioned method embodiments for shielding fuzzy distance values ​​are implemented, such as Figure 2 Alternatively, when the processor 40 executes the computer program 42, the functions of each module / unit in the above-mentioned device embodiments are realized, for example, Figure 3 The functions of the units 310 to 330 are shown.

[0137] Exemplarily, the computer program 42 may be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, which are used to describe the execution process of the computer program 42 in the device 4 for shielding the fuzzy distance value of the distance measurement system. For example, the computer program 42 may be divided into an acquisition module, a calculation module, and a processing module, and the functions of each module are as follows:

[0138] An acquisition module, used to acquire an electrical signal corresponding to a signal light beam reflected by the object to be measured;

[0139] A calculation module, used for calculating the target distance value of the object to be measured according to the electrical signal;

[0140] The processing module is used to shield the fuzzy distance value if the target distance value is determined to be a fuzzy distance value according to the photon signal and the resolution threshold, or according to the photon signal and the signal photon number threshold.

[0141] The device 4 for shielding the fuzzy distance value of the distance measurement system may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will appreciate that Figure 4 It is only an example of the device 4 for shielding the fuzzy distance value and does not constitute a limitation of the device 4 for shielding the fuzzy distance value. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the device 4 for shielding the fuzzy distance value of the distance measurement system may also include input and output devices, network access devices, buses, etc.

[0142] The processor 40 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0143] The memory 41 may be an internal storage unit of the device 4 for shielding the fuzzy distance value, such as a hard disk or memory of the device 4 for shielding the fuzzy distance value. The memory 41 may also be an external storage device of the device 4 for shielding the fuzzy distance value, such as a plug-in hard disk, a smart memory card (SmartMedia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the device 4 for shielding the fuzzy distance value. Further, the memory 41 may also include both an internal storage unit and an external storage device of the device 4 for shielding the fuzzy distance value of the distance measurement system. The memory 41 is used to store the computer program and other programs and data required by the device for shielding the fuzzy distance value. The memory 41 may also be used to temporarily store data that has been output or is to be output.

[0144] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0145] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0146] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0147] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0148] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0149] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0150] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals. The present invention is not limited to the above-mentioned embodiments. If various changes or modifications to the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the scope of the claims and equivalent technologies of the present invention, the present invention is also intended to include these changes and modifications.

Claims

1. A distance measurement system, characterized in that: include: A transmitter configured to transmit a signal light beam having a pulse period of a first time toward the object to be detected; A collector, configured to collect part of the signal light beam reflected by the object to be measured and output a photon signal, wherein the effective working time of the collector is a second time, and the second time is less than the first time; A processing circuit is connected to the transmitter and the collector. The processing circuit calculates the target distance value of the object to be measured according to the photon signal. When the target distance value is determined to be a fuzzy distance value according to the photon signal and a resolution threshold, or according to the photon signal and a signal photon number threshold, the fuzzy distance value is shielded.

2. The distance measurement system according to claim 1, characterized in that: The collector comprises a pixel unit, wherein the pixel unit comprises a plurality of pixels, and the pixels are used to respond to a single photon in a portion of the signal light beam reflected back by the object to be measured and output the photon signal; The collector further comprises a readout circuit, and the readout circuit is used to output a histogram according to the photon signal; The processing circuit is also used to calculate the number of ambient photons and the number of signal photons according to the histogram; determine that the target distance value is a fuzzy distance value according to the number of ambient photons, the number of signal photons and a resolution threshold, or according to the number of signal photons and a preset signal photon number threshold, and then shield the fuzzy distance value.

3. The distance measurement system according to claim 2, characterized in that: The resolution threshold includes a preset quantitative resolution threshold or a variable resolution threshold; the variable resolution threshold is determined according to the average value of ambient light illumination.

4. The distance measurement system according to claim 2 or 3, characterized in that: The processing circuit calculates the target resolution of the object to be measured according to the number of signal photons and the number of ambient photons. If the target resolution is greater than the resolution threshold, or the target resolution is greater than or equal to the resolution threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded; or If the processing circuit determines that the number of signal photons is less than the signal photon number threshold, or that the number of signal photons is less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

5. The distance measurement system according to claim 4, characterized in that: The target resolution of the object to be measured is calculated according to the following first function model or second function model: The first function model is: The second function model is: Among them, C s is the number of signal photons; C n is the number of ambient photons; a, b, c, d, e are all parameters; f represents the focal length of the collector lens; Resolution is the target resolution.

6. The distance measurement system according to claim 3, characterized in that: The processing circuit determines a first ranging range and a second ranging range according to the first time and the second time; obtains a first resolution range corresponding to the first ranging range and a second resolution range corresponding to the second ranging range; and determines the preset quantitative resolution threshold according to the first resolution range and the second resolution range.

7. The distance measurement system according to claim 3, characterized in that: The processing circuit calculates the mean ambient light illumination value according to the signal photon number and the ambient photon number; determines the variable resolution threshold value according to the mean ambient light illumination value and a preset fitting function relationship, wherein the preset fitting function relationship includes the relationship between the variable resolution threshold value and the mean ambient light illumination value.

8. The distance measurement system according to claim 7, characterized in that: The processing circuit obtains the number of signal photons and the number of ambient photons corresponding to different initial sampling points, and calculates the sampling resolution of each of the initial sampling points according to the number of signal photons and the number of ambient photons; if the sampling resolution of any initial sampling point is less than a preset sampling resolution threshold, or the sampling resolution is less than or equal to the preset sampling resolution threshold, the initial sampling point is marked as a target sampling point; The average value of the ambient light illumination is calculated according to the number of signal photons and the number of ambient photons at the target sampling point.

9. The distance measurement system according to claim 8, characterized in that: The processing circuit calculates the reflectivity corresponding to each of the target sampling points according to the number of signal photons at each of the target sampling points and a pre-stored reflectivity calculation rule; calculates the sampling ambient light irradiance corresponding to each of the target sampling points according to the number of ambient photons at each of the target sampling points, the corresponding reflectivity, and a pre-stored ambient light irradiance calculation rule; calculates the sampling ambient light illumination corresponding to each of the target sampling points according to the sampling ambient light irradiance corresponding to each of the target sampling points, and calculates the ambient light illumination mean according to the sampling ambient light illumination corresponding to each of the target sampling points.

10. The distance measurement system according to claim 9, characterized in that: The pre-stored reflectivity calculation rule is: Where Re is the reflectivity of the object under test at any target sampling point; C ns is the number of signal photons at the target sampling point; TCSPC is the number of pulses emitted in a priori single-frame measurement; θ is the incident angle of light; L is the measurement distance of the object being measured; P t is the peak power of the signal beam emitted by the light source; k1 is the first preset coefficient; The calculation rule of the pre-stored ambient light irradiance is: Among them, I AL is the ambient light irradiance at any target sampling point; C ns is the number of signal photons at the target sampling point; C nn is the number of ambient photons at the target sampling point; θ is the incident angle of light; L is the measurement distance of the object to be measured; f represents the focal length of the collector lens; k2 is the second preset coefficient, and k3 is the third preset coefficient.

11. A method for shielding fuzzy distance values, characterized in that: include: Acquire a photon signal corresponding to a signal light beam reflected by the object to be measured; wherein the emission pulse period of the signal light beam is a first time, the effective acquisition time of the signal light beam is a second time, and the second time is less than the first time; Calculate the target distance value of the object to be measured according to the photon signal; When the target distance value is determined to be a fuzzy distance value according to the photon signal and the resolution threshold, or according to the photon signal and the signal photon number threshold, the fuzzy distance value is shielded.

12. The method for shielding fuzzy distance values ​​according to claim 11, characterized in that: When the target distance value is determined as a fuzzy distance value according to the photon signal and the resolution threshold, or according to the photon signal and the signal photon number threshold, the fuzzy distance value is shielded, including: Acquiring the number of signal photons and the number of ambient photons; the number of signal photons and the number of ambient photons are determined according to the photon signal; If the target distance value is determined to be a fuzzy distance value based on the number of ambient photons, the number of signal photons and a resolution threshold, or based on the number of signal photons and a preset signal photon number threshold, the fuzzy distance value is shielded.

13. The method for shielding fuzzy distance values ​​according to claim 12, characterized in that: If the target distance value is determined to be a fuzzy distance value according to the number of ambient photons, the number of signal photons and a resolution threshold, or according to the number of signal photons and a preset signal photon number threshold, then shielding the fuzzy distance value includes: Calculate the target resolution of the object to be measured according to the signal photon number and the ambient photon number; if the target resolution is greater than a resolution threshold, or the target resolution is greater than or equal to the resolution threshold, determine the target distance value as a fuzzy distance value, and shield the fuzzy distance value; or, If it is determined that the number of signal photons is less than the signal photon number threshold, or the number of signal photons is less than or equal to the signal photon number threshold, the target distance value is determined to be a fuzzy distance value, and the fuzzy distance value is shielded.

14. The method for shielding fuzzy distance values ​​according to any one of claims 11 to 13, characterized in that: The resolution threshold includes a preset quantitative resolution threshold or a variable resolution threshold; The variable resolution threshold is determined according to the average value of the ambient light illumination.

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