Laser radar ranging method and system, laser radar, automobile and medium

Abstract

The invention provides a laser radar ranging method and system, a laser radar, an automobile and a medium, and the method comprises the steps: carrying out the peak interval interception of an obtained histogram curve, and obtaining all peak curves; corresponding pulse width coefficients, centroid moments and distance pulse width interval groups are obtained through a centroid method for interpolation peak value curves obtained through interpolation of all the peak value curves, and centroid interval interception is conducted on all the interpolation peak value curves according to the centroid moments to obtain centroid sliding window curves; performing cross-correlation operation on each centroid sliding window curve and a standard peak curve obtained by grouping and comparing the distance pulse width intervals to obtain correlation time, and correcting the correlation time based on the pulse width coefficient of the centroid sliding window curve and the reference pulse width coefficient of the standard peak curve; and obtaining a target distance by combining the reference distance of the standard peak curve, and obtaining a distance measurement result based on a preset output mode. According to the invention, the accuracy of TOF time extraction can be effectively ensured, and the precision and resolution of distance measurement are improved.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a laser radar ranging method, system, laser radar, automobile and medium. Background Art

[0002] LiDAR calculates distance by measuring the time of flight (TOF) of optical pulse signals. The actual received pulse signal usually has a time width of several ns to more than ten ns. When a high-precision TDC or ADC is used to sample the received signal, the time resolution of the pulse curve is very high, usually tens of picoseconds to hundreds of picoseconds, and there are detailed rising and falling edge data. Only the rising edge or peak time (TOF time for short) can be simply calculated to achieve high-precision distance calculation, and the ranging accuracy is usually ±3 to 5cm.

[0003] For the pulse response received by the single photon avalanche photodiode (SPAD) chip, the avalanche photodiode (APD) chip based on analog-to-digital converter (ADC) sampling, and the silicon photomultiplier (SIPM) array chip based on analog-to-digital converter (ADC) sampling, as shown in the figure below: Figure 1 The target echo signal in the histogram curve shown is a non-ideal pulse signal, which can be divided into a rising segment, a peak segment, and a falling segment. The rising segment is generally 2 to 6 ns, and the sampling points are insufficient. Especially for stronger echoes, the rising segment has only 1 to 2 sampling points, which cannot accurately describe the rising process of the signal. Therefore, when using the traditional rising edge / peak method to solve the distance, there is usually an error of about 1ns, resulting in a ranging accuracy and resolution of about 15cm, which cannot be used directly. Even if interpolation is performed, the ranging accuracy cannot be effectively improved. Although the industry usually uses the centroid method or the correlation distance method to analyze and extract the TOF moment for distance solution; however, the centroid method is more suitable for the extraction of left-right symmetrical pulse waveforms. It cannot accurately extract the TOF moment for response signals that are left-right asymmetric and have certain irregularities with pulse width changes; at the same time, the correlation distance method uses a single pulse waveform and a standard waveform for cross-correlation operations. For asymmetric echoes with steep rising segments and gentle falling segments, it tends to make the peak segments of the two waveforms overlap faster, rather than matching the entire waveform envelope. As a result, the solution accuracy is easily affected by the pulse width and shape of the waveform. When fine pulse width change acquisition cannot be achieved, it is difficult to guarantee the distance measurement accuracy. Summary of the invention

[0004] In order to solve the problems of the prior art, it is necessary to provide a laser radar ranging method, system, laser radar, automobile and medium to address the above technical problems.

[0005] In a first aspect, an embodiment of the present invention provides a laser radar ranging method, the method comprising the following steps:

[0006] Acquire a histogram curve, where the histogram curve is generated according to the number of photons received by the photosensor within a preset time range;

[0007] According to the extraction of the peak value in the histogram curve and the peak interval interception of the histogram curve, all the peak curves in the histogram curve are obtained;

[0008] According to the interpolation of each peak curve in all the peak curves, an interpolation peak curve corresponding to each peak curve is obtained respectively;

[0009] According to the centroid method operation performed on each of the interpolation peak curves, the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each of the interpolation peak curves are obtained;

[0010] Performing centroid interval interception on each interpolation peak curve according to the centroid moment of each interpolation peak curve to obtain a centroid sliding window curve corresponding to each interpolation peak curve;

[0011] According to each of the centroid sliding window curves and the distance pulse width interval grouping, and comparing with the standard curve, a standard peak curve corresponding to each of the centroid sliding window curves is obtained;

[0012] According to performing a cross-correlation operation on each of the centroid sliding window curves and the standard peak curve corresponding to each of the centroid sliding window curves, a correlation time between each of the centroid sliding window curves and the corresponding standard peak curve is obtained;

[0013] Obtaining a corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time;

[0014] Obtaining a target distance corresponding to each of the centroid sliding window curves according to each of the corrected correlation times and a reference distance of a standard peak curve corresponding to each of the centroid sliding window curves;

[0015] According to the target distance of all centroid sliding window curves, the ranging result is obtained based on the preset output mode.

[0016] In a second aspect, an embodiment of the present invention provides a laser radar ranging system, the system comprising:

[0017] A histogram curve acquisition module, used to acquire a histogram curve, wherein the histogram curve is generated according to the number of photons received by the photosensor within a preset time range;

[0018] A peak curve extraction module, used for obtaining all peak curves in the histogram curve by extracting peak values ​​in the histogram curve and intercepting peak intervals of the histogram curve;

[0019] A peak curve interpolation module, used for obtaining interpolated peak curves corresponding to each peak curve according to the interpolation of each peak curve in all the peak curves;

[0020] A peak curve grouping module, used to obtain the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each interpolation peak curve according to the centroid method operation performed on each interpolation peak curve;

[0021] A centroid sliding window interception module, used for intercepting the centroid interval of each interpolation peak curve according to the centroid moment of each interpolation peak curve, to obtain the centroid sliding window curve corresponding to each interpolation peak curve;

[0022] A standard peak curve acquisition module, used for comparing each of the centroid sliding window curves and the distance pulse width interval grouping with the standard curve to obtain a standard peak curve corresponding to each of the centroid sliding window curves;

[0023] A cross-correlation analysis module, configured to obtain a correlation time between each of the centroid sliding window curves and the corresponding standard peak curve by performing a cross-correlation operation on each of the centroid sliding window curves and the standard peak curve corresponding to each of the centroid sliding window curves;

[0024] A correlation time correction module, used for obtaining a corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time;

[0025] A distance calculation module, used for obtaining the target distance corresponding to each of the centroid sliding window curves according to each of the corrected correlation times and the reference distance of the standard peak curve corresponding to each of the centroid sliding window curves;

[0026] The distance measurement result output module is used to output the distance measurement result based on a preset output mode according to all target distances.

[0027] In a third aspect, an embodiment of the present invention further provides a laser radar, which includes a laser transmitting end, a photosensitive sensor and a controller; the controller includes a processor and a memory, the processor and the memory are coupled, the memory is used for computer programs or instructions, and the processor is used to execute the computer programs or instructions in the memory, so that the controller performs the steps of the above-mentioned laser radar ranging method.

[0028] In a fourth aspect, an embodiment of the present invention further provides a car on which a laser radar ranging device is deployed, wherein the laser radar ranging device includes a memory, a processor, and a laser radar ranging program stored in the memory and executable on the processor, wherein the laser radar ranging program is configured with steps for implementing the above-mentioned laser radar ranging method.

[0029] In a fifth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the above-mentioned laser radar ranging method are implemented.

[0030] Compared with the existing technology, the present invention can well cope with the response signal scenarios in which insufficient sampling in the rising section, left-right asymmetry and certain irregularity with pulse width change occur in lidar ranging, effectively ensure the accuracy of TOF moment extraction, and thus improve the accuracy and resolution of distance measurement, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of a target echo signal of a non-ideal pulse signal in a histogram curve;

[0032] Figure 2 is a schematic diagram of a flow chart of a laser radar ranging method in an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of the peak moment in the histogram curve in an embodiment of the present invention;

[0034] Figure 4 is a schematic diagram of a peak curve extracted based on peak time in an embodiment of the present invention;

[0035] Figure 5 is a schematic diagram of a scenario in which multiple target echo signals exist simultaneously in a histogram curve in an embodiment of the present invention;

[0036] Figure 6 is a schematic diagram of an interpolation peak value curve and a corresponding integral value time curve in an embodiment of the present invention;

[0037] Figure 7 is a schematic diagram of obtaining the centroid moment when the interpolation peak curve is a symmetrical curve in an embodiment of the present invention;

[0038] Figure 8 is a schematic diagram of an interpolation peak curve of a ratio of an ascending section slope to a descending section slope within a preset range in an embodiment of the present invention;

[0039] Fig. 9 1 is a schematic diagram of calculating the half-height full pulse width coefficient of the interpolation peak curve in an embodiment of the present invention;

[0040] Fig.10 is another schematic diagram for calculating the half-height full pulse width coefficient of the interpolation peak curve in an embodiment of the present invention;

[0041] Fig.11 is a schematic diagram of an interpolation peak curve when the ratio of the slope of the rising section to the slope of the falling section exceeds a preset range in an embodiment of the present invention;

[0042] Fig.12 is a schematic diagram of calculating the rising pulse width coefficient of the interpolation peak curve in an embodiment of the present invention;

[0043] Fig.13 is another schematic diagram for calculating the rising pulse width coefficient of the interpolation peak curve in an embodiment of the present invention;

[0044] Fig.14 In the embodiment of the present invention, Figure 6 The schematic diagram of the centroid sliding window curve obtained by intercepting the centroid interval at the centroid moment is shown;

[0045] Fig.15 is a schematic diagram of standard peak curve translation in cross-correlation calculation in an embodiment of the present invention;

[0046] Fig.16 1 is a schematic diagram of a normalized curve of a cross-correlation coefficient under different translation step sizes in a cross-correlation operation in an embodiment of the present invention;

[0047] Fig.17 is a schematic diagram of cross-correlation values ​​obtained by shifting and aligning the standard peak curve and the centroid sliding window curve according to rising edge alignment and falling edge alignment in an embodiment of the present invention;

[0048] Fig.18 Schematic diagram comparing the distance resolution effect of the method of the present invention and the existing conventional distance resolution method;

[0049] Fig.19 Schematic diagram of the comparison of the distance resolution error between the method of the present invention and the conventional distance resolution method;

[0050] Fig. 20 It is a structural schematic diagram of a laser radar ranging system in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical scheme and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the embodiments described below are part of the embodiments of the present invention and are only used to illustrate the present invention, but are not used to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] In the description of the present invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing the embodiments and are not intended to limit the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0053] like Figure 2 As shown, the present invention provides a laser radar ranging method, comprising the following steps:

[0054] S1. Obtain a histogram curve, wherein the histogram curve is generated according to the number of photons received by the photosensor within a preset time range; wherein the preset time range can be determined according to the actual distance measurement application requirements and is not specifically limited here; the photosensor is a core component in a laser radar for capturing and collecting laser pulses reflected from a target, thereby realizing accurate measurement of characteristics such as target distance, speed, and direction; in some embodiments, the photosensor is a single-photon avalanche photodiode linear array chip (SPAD linear array chip), a single-photon avalanche photodiode area array chip (SPAD area array chip), an avalanche photodiode chip based on analog-to-digital converter sampling (APD+ADC), or a silicon photomultiplier tube array chip based on analog-to-digital converter sampling (SIPM+ADC); that is, the laser radar ranging method provided by the present invention is suitable for laser radars that integrate the above-mentioned photosensor types.

[0055] In practical applications, the echo signal received by each pixel of the photosensitive sensor is counted using the time-correlated single-photon counting (TCSPC) method to obtain the corresponding histogram curve. This curve is a one-dimensional waveform curve of the signal intensity changing with time. The horizontal axis is time, the unit is ns, and the corresponding time resolution varies depending on the time resolution of the photosensitive sensor; the vertical axis is the signal intensity. When there is no target, the intensity value is basically 0, which is called the background noise. The echo exceeding a certain range of the background noise (signal-to-noise ratio or threshold) is called the target echo, which is the analysis basis for distance calculation.

[0056] S2. According to the extraction of the peak values ​​in the histogram curve and the peak interval interception of the histogram curve, all the peak curves in the histogram curve are obtained; wherein, all the peak curves can be understood as curve segments corresponding to all the peak interval ranges in the histogram curve obtained by using the extreme value extraction method.

[0057] In some embodiments, the steps of extracting the peak value from the peak value in the histogram curve and intercepting the peak interval of the histogram curve include:

[0058] According to the extreme value extraction of the histogram curve, all peak moments in the histogram curve are obtained; wherein, the extreme value extraction can be understood as the process of searching for all peaks in the histogram curve, which can be implemented by using relevant existing technologies and will not be described in detail here. The horizontal coordinate position corresponding to each peak in the histogram curve is called the peak moment, such as Figure 3 As shown, there is a maximum value at the position of 81ns in a histogram curve, and the corresponding peak time 81ns is the peak time to be extracted.

[0059] The data within the preset sliding window width range before and after each peak moment in the histogram curve is extracted; wherein, the preset sliding window width range can be understood as the sliding window size used to intercept the curve segment corresponding to each peak moment. In principle, each peak moment can be taken as the center, and the data within a period of time before and after it can be symmetrically extracted as a separate curve as the required peak curve. However, considering that there are asymmetric echo signal scenarios in actual applications, in order to ensure that the intercepted peak curve can provide more analysis information, in some embodiments, the preset sliding window width range is further set to include a first interval and a second interval before and after the peak moment; the width of the first interval is smaller than the width of the second interval. For example, the first interval in the preset sliding window width range can be set to [peak moment - 0.7*preset pulse width, peak moment], and the second interval can be set to [peak moment, peak moment + 1.2*preset pulse width], that is, 1.9 times the preset pulse width is taken, wherein the preset pulse width varies depending on the transceiver device, and can be 10 to 20ns. Based on Figure 3 At the peak moment shown in the figure, when the preset pulse width is 20ns, the corresponding preset sliding window width range is [67,105], that is, the data of the horizontal axis 67ns to 105ns needs to be stored separately, and the result is Figure 4 A peak curve is shown.

[0060] It should be noted that in actual applications, there may be multiple peaks in the histogram curve corresponding to a certain time range. That is, the light beam of a single channel of the laser radar may encounter multiple targets in sequence during propagation, thereby receiving multiple echo signals. Through the above peak extraction and peak interval interception, multiple peak curves can be obtained, and the time length and number of data points of each peak curve are consistent. Figure 5 As shown in the figure, during the detection of a channel of the 192-line vehicle-mounted laser radar, the laser beam first irradiates the translucent glass at a distance of 1 meter, at which time an echo with a peak intensity of 50 is returned, then it rubs the edge of the road railing at a distance of 5 meters, at which time an echo with a peak intensity of 100 is returned, and finally it irradiates the white wall at a distance of 10 meters, returning an echo with a peak intensity of 500. Then, in the process of extracting the extreme value of the above histogram curve, three peak moments will be obtained, and the corresponding three peak curves can be obtained by sliding window interception of each peak moment according to the above method.

[0061] S3. According to the interpolation of each peak curve in all the peak curves, the interpolation peak curves corresponding to each peak curve are obtained respectively; wherein, the interpolation ratio and the interpolation method can be set according to the actual hardware processing performance. In some embodiments, according to the interpolation of each peak curve in all the peak curves, the interpolation ratio of the interpolation peak curves corresponding to each peak curve is obtained in the range of 100 to 1000 and / or the interpolation method is one of linear interpolation, cubic spline interpolation and piecewise cubic Hermite interpolation; for example, for the original curve with a time resolution of 1ns, the time resolution after interpolation is 0.01ns to 0.001ns. By interpolating each segment of the extracted peak curve, the time resolution of the horizontal coordinate of the peak curve can be effectively improved.

[0062] S4. According to the centroid method operation performed on each of the interpolation peak curves, the pulse width coefficient, centroid moment and distance-to-pulse width interval grouping corresponding to each of the interpolation peak curves are obtained; wherein the centroid method can be understood as a distance calculation method that integrates the segmented single pulse waveforms to obtain the centroid moment as the TOF moment. In the embodiment of the present invention, this method is used to preliminarily calculate the distance, which is mainly used to group the distance pulse width of each interpolation peak curve, so as to facilitate the subsequent use of the related distance method for reliable distance solution.

[0063] In some embodiments, the step of obtaining the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each interpolation peak curve according to the centroid method operation performed on each interpolation peak curve comprises:

[0064] According to the discrete numerical integration of each interpolation peak curve, the integral value time curve and the total integral area corresponding to each interpolation peak curve are obtained respectively; wherein the discrete numerical integration can be understood as the accumulation of discrete data, and the integral value corresponding to each horizontal coordinate on the interpolation peak curve is i represents the data number, and Y(i) represents the corresponding ordinate value of the curve; based on the integral value corresponding to each abscissa, we can get Figure 6 The integral value time curve of the entire interpolation peak curve is shown, and the corresponding total integral area S can be obtained.

[0065] According to the preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, the centroid moment of each of the interpolation peak curves is obtained; the centroid moment is the horizontal coordinate position on the interpolation peak curve that matches the product of the preset centroid coefficient and the total integrated area, that is, assuming that k0 is the preset centroid coefficient, it is necessary to find (or be closest to) the horizontal coordinate position of S(i) = k0*S in the integral value time curve as the centroid moment.

[0066] In some embodiments, when the interpolation peak curve is a symmetrical curve, the preset centroid coefficient is set to 0.5; when the interpolation peak curve is an asymmetrical curve and biased toward the rising edge, the preset centroid coefficient is in the range of 0.4 to 0.5; when the interpolation peak curve is an asymmetrical curve and biased toward the falling edge, the preset centroid coefficient is in the range of 0.5 to 0.8. For example, the rising edge of the SPAD response is steep and there is insufficient sampling. It is generally biased toward the falling edge, and the preset centroid coefficient can be set to 0.6. Figure 6 The blue curve is the interpolation peak curve obtained after 100 times interpolation, with a time resolution of 0.01ns and a peak position of 81ns (indicated by the blue mark); the black curve is the integral value time curve. When k0 = 0.5, Figure 7 The method shown obtains the centroid moment position of 81.77ns (indicated by the red mark).

[0067] According to the distance solution performed on the centroid moment of each interpolation peak curve, the initial distance corresponding to each interpolation peak curve is obtained; wherein the initial distance can be expressed as:

[0068]

[0069] Among them, d1 represents the initial distance; c represents the speed of light, and t1 represents the center of mass moment.

[0070] The pulse width coefficient of each interpolation peak curve is obtained, and according to the pulse width coefficient of each interpolation peak curve and the initial distance, the distance pulse width interval grouping corresponding to each interpolation peak curve is obtained; wherein, the pulse width coefficient of the interpolation peak curve is mainly used for data grouping of the interpolation peak curve and subsequent matching of the standard curve, and it is not necessary to obtain an objective and accurate pulse width value here. However, considering the asymmetric characteristics of the actual interpolation peak curve, in order to ensure the simplicity and rationality of the pulse width coefficient acquisition as much as possible, the pulse width coefficient acquisition method is distinguished according to the ratio of the slope of the rising section and the slope of the falling section of the interpolation peak curve.

[0071] For some nearly symmetrical waveforms, such as Figure 8 As shown, the slope of the rising segment is almost equal to the slope of the falling segment (the centroid is close to the peak position), that is, the deviation is small, and it can be directly approximated as a symmetrical curve. In some embodiments, the pulse width coefficient includes a half-height full pulse width coefficient; when the ratio of the slope of the rising segment to the slope of the falling segment of the interpolation peak curve is within a preset range, the step of obtaining the pulse width coefficient of each of the interpolation peak curves includes:

[0072] According to the time difference between the right half peak moment and the left half peak moment of each interpolation peak curve, the half-height full pulse width coefficient corresponding to each interpolation peak curve is obtained; that is, when the ratio of the slope of the rising section to the slope of the falling section of the interpolation peak curve is within the preset range, Fig. 9 The half-height full pulse width coefficient corresponding to the interpolation peak curve shown is used as the pulse width coefficient used for data grouping. It should be noted that the preset range can be set according to actual application requirements. Considering that when the slope of the rising section is generally similar to the slope of the falling section, the ratio of the slope of the rising section to the slope of the falling section will be in the range of 1:1 to 3:1, in some embodiments, the preset range is set to 1:1 to 3:1, that is, when the ratio of the slope of the rising section to the slope of the falling section of the interpolation peak curve is within 1:1 to 3:1, the half-height full pulse width coefficient is directly used as the pulse width coefficient used for data grouping, and for the interpolation peak curve whose ratio of the slope of the rising section to the slope of the falling section exceeds 3:1, the following rising pulse width coefficient is used as the pulse width coefficient used for data grouping.

[0073] In practical applications, in addition to directly using the interpolation peak curve to determine the pulse width coefficient, it can also be obtained based on the analysis of the integral value time curve in the centroid method. In some embodiments, the pulse width coefficient includes a half-height full pulse width coefficient; when the ratio of the slope of the rising section and the slope of the falling section of the interpolation peak curve is within a preset range, the step of obtaining the pulse width coefficient of each of the interpolation peak curves includes:

[0074] According to the first preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, the first centroid moment of each of the interpolation peak curves is obtained; the first centroid moment is the horizontal coordinate position on the interpolation peak curve that matches the product of the first preset centroid coefficient and the total integrated area; that is, assuming that k1 is the first preset centroid coefficient, it is necessary to find the horizontal coordinate position of (or closest to) k1*S in the integral value time curve as the first centroid moment.

[0075] According to the second preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, the second centroid moment of each of the interpolation peak curves is obtained; the second centroid moment is the horizontal coordinate position on the interpolation peak curve that matches the product of the second preset centroid coefficient and the total integrated area; that is, assuming that k2 is the second preset centroid coefficient, it is necessary to find the horizontal coordinate position of (or closest to) k2*S in the integral value time curve as the second centroid moment.

[0076] According to the time difference between the second centroid moment and the first centroid moment of each interpolation peak curve, the half-height full pulse width coefficient corresponding to each interpolation peak curve is obtained; that is, the difference between the horizontal coordinate position corresponding to k2*S (second centroid moment) and the horizontal coordinate position corresponding to k1*S (first centroid moment) is the required half-height full pulse width coefficient.

[0077] It should be noted that the first preset centroid coefficient k1 and the second preset centroid coefficient k2 can be adjusted according to the tail shape of the actual interpolation peak curve; in some embodiments, in order to ensure that it is suitable for more application scenarios, the range of the first preset centroid coefficient is 0.1-0.2; the range of the second preset centroid coefficient is 0.8-0.9. For example, when k1=0.1 and k2=0.8, the centroid concept is expanded, and the horizontal coordinate position corresponding to 0.1*total integral value is used to represent the first centroid moment, and the horizontal coordinate position corresponding to 0.8*total integral value is used to represent the second centroid moment, that is, Fig.10 As shown in the figure, the half-height full pulse width coefficient is W1=6.1ns. That is, when the ratio of the slope of the rising section and the slope of the falling section of the interpolation peak curve is within the preset range, it can also be achieved by Fig.10 The method shown results in pulse width factors which are used as data packets.

[0078] In addition, for Fig.11In the scenario where the difference between the rising and falling slopes of the interpolation peak curve shown is particularly large (i.e., the ratio of the rising and falling slopes exceeds 3:1), the half-height full pulse width coefficient obtained by the above method as the pulse width coefficient used for data grouping may not match the appropriate standard curve, thereby affecting the subsequent ranging accuracy. For this special case, a more suitable rising pulse width coefficient needs to be used. In some embodiments, the pulse width coefficient includes a rising pulse width coefficient; when the ratio of the rising and falling slopes of the interpolation peak curve exceeds a preset range, the step of obtaining the pulse width coefficients of each of the interpolation peak curves includes:

[0079] According to the time difference between the peak moment and the left half peak moment of each interpolation peak curve, the rising pulse width coefficient corresponding to each interpolation peak curve is obtained; wherein the rising pulse width coefficient can be obtained by Fig.12 The method shown is obtained.

[0080] Similarly, in practical applications, in addition to directly using the interpolation peak curve to determine the rising pulse width coefficient, it can also be obtained based on the analysis of the integral value time curve in the centroid method. In some embodiments, the pulse width coefficient includes a rising pulse width coefficient; when the ratio of the rising section slope and the falling section slope of the interpolation peak curve exceeds a preset range, the step of obtaining the pulse width coefficient of each of the interpolation peak curves includes:

[0081] According to the third preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, the third centroid moment of each of the interpolation peak curves is obtained; the third centroid moment is the horizontal coordinate position on the interpolation peak curve that matches the product of the third preset centroid coefficient and the total integrated area; that is, assuming that k3 is the third preset centroid coefficient, it is necessary to find the horizontal coordinate position of (or closest to) k3*S in the integral value time curve as the third centroid moment.

[0082] According to the fourth preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, the fourth centroid moment of each of the interpolation peak curves is obtained; the fourth centroid moment is the horizontal coordinate position on the interpolation peak curve that matches the product of the fourth preset centroid coefficient and the total integrated area; that is, assuming that k4 is the fourth preset centroid coefficient, it is necessary to find the horizontal coordinate position of (or closest to) k4*S in the integral value time curve as the fourth centroid moment.

[0083] According to the time difference between the fourth centroid moment and the third centroid moment of each interpolation peak curve, the rising pulse width coefficient corresponding to each interpolation peak curve is obtained. That is, the difference between the horizontal coordinate position corresponding to k4*S (the fourth centroid moment) and the horizontal coordinate position corresponding to k3*S (the third centroid moment) is the required rising pulse width coefficient.

[0084] It should be noted that the third preset centroid coefficient k3 and the fourth preset centroid coefficient k4 can be determined according to the shape of the actual interpolation peak curve; in some embodiments, the third preset centroid coefficient ranges from 0.1 to 0.2; the fourth preset centroid coefficient ranges from 0.5 to 0.6; when k3 = 0.1 and k4 = 0.5, the following can be obtained: Fig.13 The rising pulse width coefficient is shown.

[0085] Although the distance is solved by the centroid method above, it cannot be used as the final distance because the centroid position extraction deviation exists in the distance solution of the centroid method. It is only used for grouping to facilitate the subsequent screening of the corresponding standard curve. For example, for a vehicle-mounted laser radar with a range of 200 meters, the standard curve will be grouped by distance to obtain multiple distance groups such as 10 meters, 30 meters, 60 meters, 100 meters and 150 meters, and at the same distance, it will be grouped according to the different pulse width curves formed by targets with different reflectivity; assuming that at 10 meters, the echo pulse width of the standard plate with 10% reflectivity is 5ns, 50% reflectivity is 7ns, and 90% reflectivity is 8ns. If the initial distance obtained by the centroid method above is 6 meters and the pulse width coefficient is 6.8ns, the corresponding interpolation peak curve will be divided into the 10-meter 7ns group, and the standard curve corresponding to the group will be used to perform cross-correlation operations with it.

[0086] S5. Perform centroid interval interception on each interpolation peak curve according to the centroid moment of each interpolation peak curve to obtain the centroid sliding window curve corresponding to each interpolation peak curve; wherein, the process of obtaining the centroid sliding window curve can refer to the sliding window interception process of the aforementioned peak curve, and the difference between the two is that the interception here is centered on the more precise centroid moment, and the sliding window interception of the interpolation peak curve is performed according to the 1.5 times preset pulse width interception time range of [centroid moment - 0.5*preset pulse width, centroid moment + preset pulse width], which will not be described in detail here. Based on Figure 6 For example, the centroid time is 81.77ns. Assuming the preset pulse width is 20ns, the interception time range is [71.77, 101.77]. Then, by intercepting the centroid interval, we can get Fig.14 The centroid sliding window curve is shown.

[0087] S6. According to the grouping of each centroid sliding window curve and the distance pulse width interval, the standard peak curve corresponding to each centroid sliding window curve is compared with the standard curve; wherein the standard peak curve can be understood as a calibration curve with known parameters obtained by performing centroid method calculation on the target histogram curve of different distances and different reflectivity plates in advance in the laser radar calibration room, and each calibration curve corresponds to a calibration distance and calibration pulse width coefficient. After the obtained standard curve data set is grouped according to the distance pulse width interval, the calibrated pulse width distance peak curve data table can be stored in the internal memory of the laser radar for subsequent cross-correlation calculation.

[0088] In some embodiments, the step of constructing the standard peak curve includes:

[0089] According to the histogram data extraction under different distance and pulse width scenarios between the laser radar entity calibration, a calibration histogram curve data set is obtained; the calibration histogram curve data set includes peak curves grouped by different distance pulse width intervals; wherein, the peak curves grouped by different distance pulse width intervals can be realized by referring to the relevant existing calibration technology, which will not be repeated here.

[0090] According to the centroid method operation performed on each of the peak curves in the calibration histogram curve data set, the calibration centroid sliding window curve of each peak curve is obtained; wherein, the acquisition process of the calibration centroid sliding window curve includes first calculating the corresponding centroid moment, and then performing sliding window interception according to the corresponding centroid moment; the specific implementation method steps can refer to the aforementioned description of obtaining the centroid sliding window curve, which will not be repeated here.

[0091] Each of the calibration centroid sliding window curves is used as a standard peak curve, and the calibration distance and calibration pulse width coefficient corresponding to each of the calibration centroid sliding window curves are used as the reference distance and reference pulse width coefficient corresponding to the standard peak curve, respectively; the calibration pulse width coefficient is one of the half-height full pulse width coefficient and the rising pulse width coefficient, that is, when the deviation between the rising segment slope and the falling segment slope of the calibration centroid sliding window curve is large (exceeding the preset range), the corresponding calibration pulse width coefficient is the rising pulse width coefficient, and when the deviation between the rising segment slope and the falling segment slope of the calibration centroid sliding window curve is small (within the preset range), the corresponding calibration pulse width coefficient is the half-height full pulse width coefficient. It should be noted that the acquisition process of the half-height full pulse width coefficient and the rising pulse width coefficient can also refer to the relevant acquisition description of the pulse width coefficient of the aforementioned interpolation peak curve, which will not be repeated here.

[0092] Considering that the cross-correlation operation is sensitive to pulse width and waveform shape, in the process of constructing the actual standard peak curve, it is necessary to collect all common pulse width distributions and waveform curves as early as possible, such as single-peak curves with different pulse widths, hump curves with different degrees of superposition, etc., to provide reliable data support for the actual distance interpretation.

[0093] S7. Perform cross-correlation operation on each of the centroid sliding window curves and the standard peak curves corresponding to each of the centroid sliding window curves to obtain the correlation time between each of the centroid sliding window curves and the corresponding standard peak curve; there are many methods for performing cross-correlation operation on discrete signals, such as shift summation in the spatial domain, fast Fourier transform FFT in the frequency domain, convolution, etc. The specific method can be selected according to the hardware performance.

[0094] In some embodiments, the step of performing cross-correlation operation on each of the centroid sliding window curves and the standard peak curve corresponding to each of the centroid sliding window curves to obtain the correlation time between each of the centroid sliding window curves and the corresponding standard peak curve comprises:

[0095] According to the product accumulation value of the signal strength corresponding to the same horizontal coordinate position on the standard peak curve after translation of each centroid sliding window curve under different translation step sizes, the correlation distance between each centroid sliding window curve and the corresponding standard peak curve is obtained; the correlation distance is the translation step corresponding to the maximum product accumulation value among the product accumulation values ​​under different translation step sizes; in practical applications, such as Fig.15 As shown in , the standard peak curve is first shifted (translated according to different horizontal coordinate distances), and then the shifted standard peak curve and the centroid sliding window curve are multiplied and added item by item to obtain the corresponding product accumulation value, and then the product accumulation values ​​corresponding to all translation steps are compared to find the maximum product accumulation value as the relevant distance. Fig.16 As shown in FIG. 1 , from the normalized curves of the cross-correlation coefficients under different translation step sizes, the cross-correlation coefficient corresponding to the right shift of 142 horizontal resolutions is the largest, that is, the correlation distance is 142 horizontal resolutions.

[0096] According to the product of the correlation distance between each centroid sliding window curve and the corresponding standard peak curve and the horizontal axis time unit, the correlation time corresponding to each centroid sliding window curve and the corresponding standard peak curve is obtained; wherein the horizontal axis time unit can be understood as the horizontal axis time resolution of the standard peak curve; based on Fig.16 When the correlation distance shown is 142, the corresponding correlation time t2 = 142 * 0.01 = 1.42ns. It should be noted that the above horizontal axis time unit varies depending on the horizontal axis time resolution of the actual curve. The horizontal axis time unit used in the correlation time calculation here is only an exemplary description. The sign of the correlation time represents the direction of the horizontal shift. The negative sign indicates that the target distance is less than the calibration distance, and the positive sign indicates that the target distance is greater than the calibration distance.

[0097] S8. Obtain the corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time; wherein the corrected correlation time can be understood as the correction of the correlation time obtained by cross-correlation calculation based on discrete signals based on the error caused by the different pulse widths between the actual centroid sliding window curve and the calibration curve. Assume Fig.17 The standard peak curve shown is a curve with a pulse width of 3 ns, and the centroid sliding window curve is a curve with a pulse width of 4 ns. They are shifted and aligned according to the rising edge alignment and the falling edge alignment respectively. By calculating the product sum of each item of a certain translation step, the cross-correlation value table shown in Table 1 can be obtained.

[0098] Table 1 Cross-correlation values ​​obtained by shift alignment of rising edge alignment and falling edge alignment

[0099] Time / ns Standard peak curve Rising edge alignment Falling edge alignment 1 0.0 0.0 1.0 2 1.0 1.0 1.0 3 1.0 1.0 1.0 4 1.0 1.0 1.0 5 0.5 1.0 0.5 6 0.0 0.5 0.0 7 0.0 0.0 0.0 Cross-correlation value 3.50 3.25

[0100] As can be seen from Table 1, the cross-correlation value of the rising edge alignment is larger, indicating that the cross-correlation of the shift is stronger, which shows that for this shape of curve, the cross-correlation operation is more inclined to the rising edge alignment. However, for the case where there are few sampling points in the rising section (SPAD response), especially when the echo signal is strong and the sampling interval is large, there will be an obvious problem of insufficient distance resolution when aligning with the rising edge. It is necessary to compensate the result to align most of the envelope of the curve through the pulse width information to ensure the accuracy of the distance solution.

[0101] In some embodiments, the pulse width coefficient is one of a half-height full pulse width coefficient and a rising pulse width coefficient; the step of obtaining the corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time comprises:

[0102] The pulse width correction factor corresponding to each of the centroid sliding window curves is obtained according to the difference between the pulse width coefficient of each of the centroid sliding window curves and the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves.

[0103] It should be noted that the shapes of the centroid sliding window curve and the standard peak curve should be roughly related. In practical applications, the pulse width coefficients of the two should be consistent, and the half-height full pulse width coefficient or the rising pulse width coefficient can be selected according to the different waveforms. In some embodiments, when the ratio of the slope of the rising section and the slope of the falling section of the centroid sliding window curve is within a preset range, the pulse width coefficient is the half-height full pulse width coefficient, that is, when calculating the pulse width correction factor, the pulse width coefficient of the centroid sliding window curve and the reference pulse width coefficient of the corresponding standard peak curve both use their respective half-height full pulse width coefficients. At this time, the pulse width correction factor can be expressed as Wc1=W1-W0, where W1 represents the half-height full pulse width coefficient of the actual centroid sliding window curve, and W0 represents the half-height full pulse width coefficient of the selected standard peak curve, in units of ns.

[0104] Similarly, in other embodiments, when the ratio of the rising segment slope and the falling segment slope of the centroid sliding window curve exceeds the preset range, the pulse width coefficient is the rising pulse width coefficient, that is, when calculating the pulse width correction factor, the pulse width coefficient of the centroid sliding window curve and the baseline pulse width coefficient of the corresponding standard peak curve both use their respective rising pulse width coefficients. At this time, the pulse width correction factor needs to be corrected with the rising pulse width coefficient, which is defined as Wc2=W2-W0', where W2 represents the rising pulse width coefficient of the actual centroid sliding window curve, and W0' represents the rising pulse width coefficient of the selected standard peak curve.

[0105] According to the sum of the pulse width correction factor and the correlation time of each centroid sliding window curve, the corrected correlation time of each centroid sliding window curve is obtained; wherein, the corrected correlation time can be expressed as t3=t2+Wc1 (when the pulse width coefficient takes the half-height full pulse width coefficient) or t3=t2+Wc2 (when the pulse width coefficient takes the rising pulse width coefficient), that is, t3 is the TOF moment to be solved. Assuming that the pulse width coefficient of the standard peak curve W0=6.38ns, the pulse width correction factor Wc1=-0.28ns is obtained, which is used to correct the aforementioned correlation time t2=1.42ns, and the corrected correlation time t3=1.14ns can be obtained.

[0106] The above embodiment is based on the sensitivity of the cross-correlation operation to the waveform, and can effectively ensure the accuracy of the distance solution by using the correlation time correction method that compensates the result to align most of the envelope of the curve based on the pulse width information.

[0107] S9. According to each of the corrected related times and the reference distance of the standard peak curve corresponding to each of the centroid sliding window curves, the target distance corresponding to each of the centroid sliding window curves is obtained; wherein the target distance can be understood as the optimal measured distance obtained by correcting the reference distance corresponding to the standard peak curve based on the corrected related time obtained above.

[0108] In some embodiments, the step of obtaining the target distance corresponding to each of the centroid sliding window curves according to each of the corrected correlation times and the reference distance of the standard peak curve corresponding to each of the centroid sliding window curves comprises:

[0109] According to the distance calculation performed by taking the corrected correlation time of each of the centroid sliding window curves as the flight time, the corrected distance corresponding to each of the centroid sliding window curves is obtained; wherein the corrected distance is expressed as:

[0110]

[0111] Among them, d m represents the corrected distance; c represents the speed of light; t3 represents the corrected correlation time (TOF moment).

[0112] The target distance of each centroid sliding window curve is obtained according to the sum of the correction distance of each centroid sliding window curve and the reference distance of the standard peak curve corresponding to each centroid sliding window curve; wherein the target distance is expressed as:

[0113] d=d m +d0

[0114] Where, d represents the target distance; d m represents the corrected distance; d0 represents the reference distance corresponding to the standard peak curve.

[0115] The target distance corresponding to each peak curve can be obtained through the above method steps, and the accurate distance resolution of each echo signal in the histogram curve can be achieved, that is, multiple target information can be obtained.

[0116] S10. According to the target distance of all centroid sliding window curves, the distance measurement result is obtained based on the preset output mode; wherein the distance measurement result can be understood as the echo distance information outputted finally determined according to the actual output mode of the laser radar. In practical applications, the laser radar can set multiple output modes, such as all echo output mode, strongest echo output mode and first echo output mode. Assume that Figure 5 In the channel ranging process shown, three echo information is received, and the peak intensity of the third echo is the highest. The above-mentioned distance-solving algorithm needs to calculate the target distances of the three targets first, and then output them according to the preset output mode: if the preset output mode is the first echo output mode, the target information of 1 meter is output; if the preset output mode is the strongest echo output mode, the target information of 10 meters is output; if the preset output mode is the all echo output mode, the information of all targets is output. In practical applications, the strongest echo output mode is usually used by default, that is, after solving multiple target distance information through the above method steps, it is screened according to the peak intensity, and only the distance information corresponding to the echo with the strongest peak value is output.

[0117] The embodiment of the present invention adopts the centroid method to improve the center alignment accuracy of the two curves in the cross-correlation operation, and then performs pulse width correction on the cross-correlation operation result, thereby effectively correcting the discrete cross-correlation calculation deviation of the asymmetric curve, which can effectively improve the ranging accuracy and resolution of the laser radar.

[0118] In order to verify the application effect of the laser radar ranging method proposed in the present invention, the ranging result scenario based on the target moving 1 cm and collecting data once is compared with the conventional correlation distance method to obtain the ranging effect. Figure 18-19 The results are shown. Fig.18 It can be seen from the figure that the distance measurement results of the conventional methods have obvious step characteristics. In the linear range of 15 cm of the true distance, the solution distance result only changes by about 3 cm, and it suddenly jumps after exceeding 15 cm, showing obvious accuracy deviation and insufficient distance resolution. The distance measurement method proposed in the present invention has a higher resolution. As the true distance increases linearly, the solution distance also increases linearly without obvious step characteristics. At the same time, from Fig.19 It can be seen that the resolution error of the distance measurement method of the present invention is randomly distributed within ±3 cm, while the error of the existing conventional method is step-distributed within ±7.5 cm, which further verifies that the resolution accuracy and resolution of the method of the present invention have a significant improvement effect, and the distance measurement accuracy and distance resolution can be increased from 15 cm to 3-5 cm.

[0119] It should be noted that although the steps in the above flowchart are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders.

[0120] like Fig. 20 As shown, the present invention provides a laser radar ranging system, the system comprising:

[0121] A histogram curve acquisition module 1 is used to acquire a histogram curve, wherein the histogram curve is generated according to the number of photons received by the photosensor within a preset time range;

[0122] A peak curve extraction module 2, used for obtaining all peak curves in the histogram curve by extracting the peak values ​​in the histogram curve and intercepting the peak intervals of the histogram curve;

[0123] A peak curve interpolation module 3, used for obtaining interpolated peak curves corresponding to each peak curve according to the interpolation of each peak curve in all the peak curves;

[0124] The peak curve grouping module 4 is used to obtain the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each interpolation peak curve according to the centroid method operation performed on each interpolation peak curve;

[0125] A centroid sliding window interception module 5 is used to intercept the centroid interval of each interpolation peak curve according to the centroid moment of each interpolation peak curve to obtain the centroid sliding window curve corresponding to each interpolation peak curve;

[0126] A standard peak curve acquisition module 6 is used to obtain a standard peak curve corresponding to each centroid sliding window curve according to each of the centroid sliding window curves and the distance pulse width interval grouping, and compare them with the standard curve;

[0127] A cross-correlation analysis module 7, configured to obtain the correlation time between each centroid sliding window curve and the corresponding standard peak curve by performing cross-correlation operation on each centroid sliding window curve and the standard peak curve corresponding to each centroid sliding window curve;

[0128] A correlation time correction module 8, configured to obtain a corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time;

[0129] The distance measuring module 9 is used to obtain the target distance corresponding to each centroid sliding window curve according to each corrected correlation time and the reference distance of the standard peak curve corresponding to each centroid sliding window curve;

[0130] The distance measurement result output module 10 is used to output the distance measurement result based on a preset output mode according to all target distances.

[0131] For the specific limitations of the laser radar ranging system, please refer to the limitations of the laser radar ranging method above, and the corresponding technical effects can also be obtained equivalently, so they will not be repeated here. Each module in the above-mentioned laser radar ranging system can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0132] In some embodiments, the present invention provides a laser radar, which includes a laser transmitting end, a photosensitive sensor and a controller; the controller includes a processor and a memory, the processor and the memory are coupled, the memory is used for computer programs or instructions, and the processor is used to execute the computer programs or instructions in the memory, so that the controller performs the steps of the above-mentioned laser radar ranging method.

[0133] In some embodiments, the present invention provides a car on which a lidar ranging device is deployed, wherein the lidar ranging device includes a memory, a processor, and a lidar ranging program stored in the memory and executable on the processor, wherein the lidar ranging program is configured with steps for implementing the above-mentioned lidar ranging method.

[0134] In some embodiments, the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above-mentioned lidar ranging method when the computer program is executed by a processor.

[0135] In summary, the embodiments of the present invention provide a laser radar ranging method, system, laser radar, automobile and medium. On the basis of improving the center alignment accuracy of the two curves in the cross-correlation operation by adopting the centroid method, the pulse width correction is performed on the cross-correlation operation result to obtain the TOF moment, and then the distance value is obtained based on the obtained TOF moment solution, and the reference distance of the known standard peak curve is corrected to obtain the target distance. The technical solution effectively corrects the discrete cross-correlation calculation deviation rate of the asymmetric curve, can well cope with the response signal scenarios with insufficient sampling in the rising section, left-right asymmetry and certain irregularity with the change of pulse width in the laser radar ranging, effectively ensures the accuracy of TOF moment extraction, thereby improving the accuracy and resolution of distance measurement, and has broad application prospects.

[0136] Each embodiment in this specification is described in a progressive manner, and the same or similar parts of each embodiment can be directly referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. It should be noted that the technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The above-mentioned embodiments only express several preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principle of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the protection scope of the claims.

Claims

1. A laser radar ranging method, characterized in that: The method comprises the following steps: Acquire a histogram curve, where the histogram curve is generated according to the number of photons received by the photosensor within a preset time range; According to the extraction of the peak value in the histogram curve and the peak interval interception of the histogram curve, all the peak curves in the histogram curve are obtained; According to the interpolation of each peak curve in all the peak curves, an interpolation peak curve corresponding to each peak curve is obtained respectively; According to the centroid method operation performed on each of the interpolation peak curves, the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each of the interpolation peak curves are obtained; Performing centroid interval interception on each interpolation peak curve according to the centroid moment of each interpolation peak curve to obtain a centroid sliding window curve corresponding to each interpolation peak curve; According to each of the centroid sliding window curves and the distance pulse width interval grouping, and comparing with the standard curve, a standard peak curve corresponding to each of the centroid sliding window curves is obtained; According to performing a cross-correlation operation on each of the centroid sliding window curves and the standard peak curve corresponding to each of the centroid sliding window curves, a correlation time between each of the centroid sliding window curves and the corresponding standard peak curve is obtained; Obtaining a corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time; Obtaining a target distance corresponding to each of the centroid sliding window curves according to each of the corrected correlation times and a reference distance of a standard peak curve corresponding to each of the centroid sliding window curves; According to the target distance of all centroid sliding window curves, the ranging result is obtained based on the preset output mode.

2. The laser radar ranging method according to claim 1, characterized in that: The photosensor is one of a single-photon avalanche photodiode linear array chip, a single-photon avalanche photodiode planar array chip, an avalanche photodiode chip based on analog-to-digital converter sampling, or a silicon photomultiplier tube array chip based on analog-to-digital converter sampling.

3. The laser radar ranging method according to claim 1, characterized in that: The steps of extracting the peak value from the peak value in the histogram curve and intercepting the peak interval of the histogram curve include: According to the extreme value extraction of the histogram curve, all peak moments in the histogram curve are obtained; The data within a preset sliding window width range before and after each peak moment in the histogram curve is extracted.

4. The laser radar ranging method according to claim 3, characterized in that: The preset sliding window width range includes a first interval and a second interval before and after the peak moment; the width of the first interval is smaller than the width of the second interval.

5. The laser radar ranging method according to claim 1, characterized in that: According to the interpolation of each peak curve in the all peak curves, the interpolation magnification of the interpolation peak curve corresponding to each peak curve is obtained in a range of 100 to 1000; And / or, the interpolation method is one of linear interpolation, cubic spline interpolation and piecewise cubic Hermite interpolation.

6. The laser radar ranging method according to claim 1, characterized in that: The step of obtaining the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each interpolation peak curve according to the centroid method operation performed on each interpolation peak curve comprises: According to the discrete numerical integration of each of the interpolation peak curves, the integral value time curve and the total integral area corresponding to each of the interpolation peak curves are obtained respectively; According to the preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, the centroid moment of each of the interpolation peak curves is obtained; the centroid moment is the horizontal coordinate position on the interpolation peak curve that matches the product of the preset centroid coefficient and the total integrated area; Obtaining the initial distance corresponding to each of the interpolation peak curves according to the distance solution performed on the centroid moment of each of the interpolation peak curves; The pulse width coefficient of each interpolation peak curve is obtained, and according to the pulse width coefficient of each interpolation peak curve and the initial distance, the distance pulse width interval grouping corresponding to each interpolation peak curve is obtained.

7. The laser radar ranging method according to claim 6, characterized in that: When the interpolation peak curve is a symmetrical curve, the preset centroid coefficient is 0.5; When the interpolation peak curve is an asymmetric curve and is biased toward the rising edge, the preset centroid coefficient is in the range of 0.4 to 0.5; When the interpolation peak curve is an asymmetric curve and is biased toward a falling edge, the preset centroid coefficient is in the range of 0.5 to 0.

8.

8. The laser radar ranging method according to claim 6, characterized in that: The pulse width coefficient includes a half-height full pulse width coefficient; when the ratio of the rising section slope and the falling section slope of the interpolation peak curve is within a preset range, the step of obtaining the pulse width coefficient of each interpolation peak curve includes: The half-maximum full pulse width coefficient corresponding to each interpolation peak curve is obtained according to the time difference between the right half-peak moment and the left half-peak moment of each interpolation peak curve.

9. The laser radar ranging method according to claim 6, characterized in that: The pulse width coefficient includes a half-height full pulse width coefficient; when the ratio of the rising section slope and the falling section slope of the interpolation peak curve is within a preset range, the step of obtaining the pulse width coefficient of each interpolation peak curve includes: According to the first preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, a first centroid moment of each of the interpolation peak curves is obtained; the first centroid moment is a horizontal coordinate position on the interpolation peak curve that matches the product of the first preset centroid coefficient and the total integrated area; According to the second preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, a second centroid moment of each of the interpolation peak curves is obtained; the second centroid moment is a horizontal coordinate position on the interpolation peak curve that matches the product of the second preset centroid coefficient and the total integrated area; The half-maximum full pulse width coefficient corresponding to each of the interpolation peak curves is obtained according to the time difference between the second centroid moment and the first centroid moment of each of the interpolation peak curves.

10. The laser radar ranging method according to claim 9, characterized in that: The first preset centroid coefficient ranges from 0.1 to 0.2; the second preset centroid coefficient ranges from 0.8 to 0.

9.

11. The laser radar ranging method according to claim 9, characterized in that: The preset range is that the ratio of the slope of the rising section to the slope of the falling section of the interpolation peak curve is 1:1 to 3:

1.

12. The laser radar ranging method according to claim 6, characterized in that: The pulse width coefficient includes a rising pulse width coefficient; when the ratio of the rising section slope to the falling section slope of the interpolation peak curve exceeds a preset range, the step of obtaining the pulse width coefficient of each interpolation peak curve includes: The rising pulse width coefficient corresponding to each of the interpolation peak curves is obtained according to the time difference between the peak moment and the left half peak moment of each of the interpolation peak curves.

13. The laser radar ranging method according to claim 6, characterized in that: The pulse width coefficient includes a rising pulse width coefficient; when the ratio of the rising section slope to the falling section slope of the interpolation peak curve exceeds a preset range, the step of obtaining the pulse width coefficient of each interpolation peak curve includes: According to the third preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, a third centroid moment of each of the interpolation peak curves is obtained; the third centroid moment is a horizontal coordinate position on the interpolation peak curve that matches the product of the third preset centroid coefficient and the total integrated area; According to the fourth preset centroid coefficient and the total integrated area corresponding to each of the interpolation peak curves, a fourth centroid moment of each of the interpolation peak curves is obtained; the fourth centroid moment is a horizontal coordinate position on the interpolation peak curve that matches the product of the fourth preset centroid coefficient and the total integrated area; The rising pulse width coefficient corresponding to each of the interpolation peak curves is obtained according to the time difference between the fourth centroid moment and the third centroid moment of each of the interpolation peak curves.

14. The laser radar ranging method according to claim 13, characterized in that: The third preset centroid coefficient ranges from 0.1 to 0.2; the fourth preset centroid coefficient ranges from 0.5 to 0.

6.

15. The laser radar ranging method according to claim 1, characterized in that: The steps of constructing the standard peak curve include: Extracting histogram data under different distance and pulse width scenarios between laser radar entity calibrations to obtain a calibration histogram curve data set; the calibration histogram curve data set includes peak curves grouped by different distance pulse width intervals; Obtaining a calibrated centroid sliding window curve of each peak curve according to a centroid operation performed on each peak curve in the calibrated histogram curve data set; Each of the calibrated centroid sliding window curves is used as a standard peak curve, and the calibrated distance and calibrated pulse width coefficient corresponding to each of the calibrated centroid sliding window curves are respectively used as the reference distance and reference pulse width coefficient corresponding to the standard peak curve; the calibrated pulse width coefficient is one of the half-height full pulse width coefficient and the rising pulse width coefficient.

16. The laser radar ranging method according to claim 1, characterized in that: The step of performing cross-correlation calculation on each of the centroid sliding window curves and the standard peak curve corresponding to each of the centroid sliding window curves to obtain the correlation time between each of the centroid sliding window curves and the corresponding standard peak curve comprises: According to the product accumulation value of the signal strength corresponding to the same horizontal coordinate position on the standard peak curve after the corresponding translation of each centroid sliding window curve under different translation step sizes, the correlation distance between each centroid sliding window curve and the corresponding standard peak curve is obtained; the correlation distance is the translation step size corresponding to the maximum product accumulation value among the product accumulation values ​​under different translation step sizes; The correlation time between each of the centroid sliding window curves and the corresponding standard peak curve is obtained according to the product of the correlation distance between each of the centroid sliding window curves and the corresponding standard peak curve and the horizontal axis time unit.

17. The laser radar ranging method according to claim 1, characterized in that: The pulse width coefficient is one of a half-height full pulse width coefficient and a rising pulse width coefficient; the step of obtaining the corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time comprises: Obtaining a pulse width correction factor corresponding to each of the centroid sliding window curves according to a difference between the pulse width coefficient of each of the centroid sliding window curves and a reference pulse width coefficient of a standard peak curve corresponding to each of the centroid sliding window curves; The corrected correlation time of each of the centroid sliding window curves is obtained according to the sum of the pulse width correction factor and the correlation time of each of the centroid sliding window curves.

18. The laser radar ranging method according to claim 17, characterized in that: When the ratio of the rising section slope and the falling section slope of the centroid sliding window curve is within a preset range, the pulse width coefficient is a half-height full pulse width coefficient; when the ratio of the rising section slope and the falling section slope of the centroid sliding window curve exceeds the preset range, the pulse width coefficient is a rising pulse width coefficient.

19. The laser radar ranging method according to claim 1, characterized in that: The step of obtaining the target distance corresponding to each of the centroid sliding window curves according to each of the corrected correlation times and the reference distance of the standard peak curve corresponding to each of the centroid sliding window curves comprises: Obtaining a corrected distance corresponding to each of the centroid sliding window curves according to a distance calculation using the corrected correlation time of each of the centroid sliding window curves as the flight time; The target distance of each of the centroid sliding window curves is obtained according to the sum of the corrected distance of each of the centroid sliding window curves and the reference distance of the standard peak curve corresponding to each of the centroid sliding window curves.

20. A laser radar ranging system, characterized in that: The system comprises: A histogram curve acquisition module, used to acquire a histogram curve, wherein the histogram curve is generated according to the number of photons received by the photosensor within a preset time range; A peak curve extraction module, used for obtaining all peak curves in the histogram curve by extracting peak values ​​in the histogram curve and intercepting peak intervals of the histogram curve; A peak curve interpolation module, used for obtaining interpolated peak curves corresponding to each peak curve according to the interpolation of each peak curve in all the peak curves; A peak curve grouping module, used to obtain the pulse width coefficient, centroid time and distance pulse width interval grouping corresponding to each interpolation peak curve according to the centroid method operation performed on each interpolation peak curve; A centroid sliding window interception module, used for intercepting the centroid interval of each interpolation peak curve according to the centroid moment of each interpolation peak curve, to obtain the centroid sliding window curve corresponding to each interpolation peak curve; A standard peak curve acquisition module, used for comparing each of the centroid sliding window curves and the distance pulse width interval grouping with the standard curve to obtain a standard peak curve corresponding to each of the centroid sliding window curves; A cross-correlation analysis module, configured to obtain a correlation time between each of the centroid sliding window curves and the corresponding standard peak curve by performing a cross-correlation operation on each of the centroid sliding window curves and the standard peak curve corresponding to each of the centroid sliding window curves; A correlation time correction module, used for obtaining a corrected correlation time corresponding to each of the correlation times according to the pulse width coefficient of each of the centroid sliding window curves, the reference pulse width coefficient of the standard peak curve corresponding to each of the centroid sliding window curves, and the correlation time; A distance calculation module, used for obtaining the target distance corresponding to each of the centroid sliding window curves according to each of the corrected correlation times and the reference distance of the standard peak curve corresponding to each of the centroid sliding window curves; The distance measurement result output module is used to output the distance measurement result based on a preset output mode according to all target distances.

21. A laser radar, characterized in that: The laser radar includes a laser transmitting end, a photosensitive sensor and a controller; the controller includes a processor and a memory, the processor and the memory are coupled, the memory is used for computer programs or instructions, and the processor is used to execute the computer programs or instructions in the memory, so that the controller performs the steps of the laser radar ranging method as described in any one of claims 1 to 19.

22. A car, characterized in that: A laser radar ranging device is deployed thereon, and the laser radar ranging device includes a memory, a processor, and a laser radar ranging program stored in the memory and executable on the processor, and the laser radar ranging program is configured with steps for implementing the laser radar ranging method as described in any one of claims 1 to 19.

23. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 19 are implemented.

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