Laser ranging method, device and medium

Abstract

The present application discloses a method, device and medium for laser ranging, which relates to the field of optics. It includes: obtaining the first calibration data within the acquisition time when there is no target object; obtaining the actual data within the acquisition time when there is a target object; obtaining the first difference between the actual data in each acquisition cycle and the corresponding first calibration data, and using the first difference as the first calibrated data after calibration; determining the distance between the time-of-flight module and the target object according to the first calibrated data after calibration. In this method, the calibration data is subtracted from the actual data, so that the number of near-end photons is less than the number of photons returned by the single-photon avalanche diode when detecting the target object, and the number of photons detected due to near-end crosstalk is avoided as much as possible, which leads to the occurrence of misjudgment when calculating the distance, thereby improving the accuracy of laser ranging.

Description

Technical Field

[0001] The present application relates to the field of optics, and in particular to a laser ranging method, device and medium. Background Art

[0002] In order to measure the distance of distant objects or objects in complex environments, lasers are usually used to measure the distance of objects. For example, a time-of-flight module is composed of a vertical cavity surface emitting laser (VCSEL), a single photon avalanche diode (SPAD) and a time-to-digital converter (TDC).

[0003] In the process of distance measurement, VCSEL emits laser pulses, SPAD receives pulses reflected from the object, TDC records the time difference between SPAD receiving photons and VCSEL emitting lasers, and the moment when SPAD receives the most photons is considered as the flight time between the module and the object, and then the distance between the module and the object is calculated based on the speed of light and the flight time. Due to reasons such as near-end crosstalk (including the light ring crosstalk inside the module and the light environment crosstalk outside the module), the number of near-end photons will be too large. When the peak formed by the near-end crosstalk is higher than the peak formed by the photons reflected from the object, if the peak with the largest number of photons is used to calculate the distance, an incorrect distance will be obtained, making the distance of the measured object inaccurate.

[0004] It can be seen that how to improve the accuracy of laser ranging is a technical problem that people in this field urgently need to solve. Summary of the invention

[0005] The purpose of this application is to provide a laser ranging method, device and medium for correcting laser ranging errors, thereby improving the accuracy of laser ranging.

[0006] In order to solve the above technical problems, the present application provides a laser ranging method, comprising:

[0007] Acquire the first calibration data within the acquisition time length starting from the laser emitter emitting the laser pulse; wherein the first calibration data is the number of photons collected by the single-photon avalanche diode in each acquisition cycle within the acquisition time length when no target object exists; and the acquisition cycle is less than the acquisition time length;

[0008] Acquire actual data within the acquisition time period starting from the time when the laser emitter starts to emit a laser pulse; wherein the actual data is the number of photons collected by the single-photon avalanche diode in each of the acquisition cycles within the acquisition time period when the target object is present;

[0009] Acquire a first difference between the actual data in each acquisition cycle and the corresponding first calibration data, and use the first difference as calibrated data;

[0010] The distance between the time-of-flight module and the target object is determined based on the calibrated data.

[0011] Preferably, the acquiring the first calibration data within the acquisition duration includes:

[0012] The first calibration data is acquired within a preset time period starting from when the laser transmitter emits a laser pulse; wherein the preset time period is shorter than the acquisition time period, and the acquisition cycle is shorter than the preset time period.

[0013] Preferably, the actual data includes first actual data within the preset duration and second actual data within the remaining duration, and the remaining duration is the duration of the acquisition duration excluding the preset duration; and determining the distance between the time-of-flight module and the target object according to the calibrated data includes:

[0014] Acquire a second difference between the first actual data and the corresponding first calibration data in each acquisition period, and use the second difference as the first calibrated data within the preset time period;

[0015] Selecting a first moment corresponding to the maximum number of photons from the first calibrated data and the second actual data;

[0016] Obtaining a first product result of the speed of light and the first moment;

[0017] A half of the first product result is used as the distance between the flight time module and the target object.

[0018] Preferably, the preset time length is determined according to the distance between the single photon avalanche diode and a lens through which the laser pulse passes, and the preset time length is positively correlated with the distance from the single photon avalanche diode to the lens.

[0019] Preferably, after obtaining the actual data within the acquisition time, the method further includes:

[0020] Determine, according to the actual data, a second moment corresponding to when the number of photons is the largest;

[0021] Determining whether the second moment is within the remaining time;

[0022] If yes, obtaining a first ratio of the first actual data in each acquisition period to the corresponding first calibration data;

[0023] Obtaining a product of each of the first ratios and the corresponding first calibration data, and using each of the products as second calibration data;

[0024] Acquire a third difference between the first actual data and the corresponding second calibration data in each acquisition period, and use the third difference as the second calibrated data within the preset time period;

[0025] Selecting a third moment corresponding to the maximum number of photons from the second calibrated data and the second actual data;

[0026] When the second moment and the third moment are the same moment, obtaining a second product result of the speed of light and the second moment or the third moment;

[0027] A half of the second product result is used as the distance between the flight time module and the target object.

[0028] Preferably, after determining that the second moment is within the remaining time and before acquiring a first ratio of the first actual data in each acquisition cycle to the corresponding first calibration data, the method further includes:

[0029] Acquire a first maximum number of photons from the first actual data and acquire a second maximum number of photons from the first calibration data;

[0030] Obtaining a second ratio of the first maximum number of photons to the second maximum number of photons;

[0031] If the second ratio is greater than or equal to the threshold, the process proceeds to the step of obtaining the first ratio of the first actual data in each acquisition cycle to the corresponding first calibration data.

[0032] Preferably, the method further comprises:

[0033] When the laser emitter emits a laser pulse and hits the target object, prompt information indicating that the target object has been hit is output and / or a time corresponding to the hit of the target object is recorded.

[0034] In order to solve the above technical problems, the present application also provides a laser ranging device, comprising:

[0035] A first acquisition module is used to acquire first calibration data within an acquisition time period starting from the laser emitter emitting a laser pulse; wherein the first calibration data is the number of photons collected by the single-photon avalanche diode in each acquisition period within the acquisition time period in the absence of a target object; and the acquisition period is less than the acquisition time period;

[0036] A second acquisition module is used to acquire actual data within the acquisition time length since the laser emitter starts to emit a laser pulse; wherein the actual data is the number of photons collected by the single photon avalanche diode in each of the acquisition cycles within the acquisition time length when the target object exists;

[0037] A third acquisition module, used for acquiring a first difference between the actual data in each acquisition period and the corresponding first calibration data, and using the first difference as calibrated data;

[0038] The determination module is used to determine the distance between the time-of-flight module and the target object according to the calibrated data.

[0039] In order to solve the above technical problems, the present application also provides a laser ranging device, comprising:

[0040] Memory for storing computer programs;

[0041] A processor is used to implement the steps of the above-mentioned laser ranging method when executing the computer program.

[0042] In order to solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above laser ranging method are implemented.

[0043] The laser ranging method provided by the present application includes: starting from the laser emitter emitting a laser pulse, obtaining the first calibration data within the acquisition time; wherein the first calibration data is the number of photons collected by the single photon avalanche diode in each acquisition cycle within the acquisition time when there is no target object; the acquisition cycle is less than the acquisition time; starting from the laser emitter emitting a laser pulse, obtaining the actual data within the acquisition time; wherein the actual data is the number of photons collected by the single photon avalanche diode in each cycle within the acquisition time when there is a target object; obtaining the first difference between the actual data in each acquisition cycle and the corresponding first calibration data, and using the first difference as the calibrated data; determining the distance between the time-of-flight module and the target object according to the calibrated data. In this method, the calibration data is subtracted from the actual data, so that the number of near-end photons is less than the number of photons returned by the single photon avalanche diode when detecting the target object, and the number of photons detected due to near-end crosstalk is avoided as much as possible, which leads to the occurrence of misjudgment when calculating the distance, thereby improving the accuracy of laser ranging.

[0044] In addition, the present application also provides a laser ranging device and a computer-readable storage medium, which have the same or corresponding technical features as the above-mentioned laser ranging method and have the same effects as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A schematic diagram of a time-of-flight module ranging provided in an embodiment of the present application;

[0047] Figure 2 A dToF direct measurement flight time histogram when the near-end crosstalk noise intensity is less than the signal intensity of the object under test provided in an embodiment of the present application;

[0048] Figure 3 A dToF direct measurement flight time histogram when the near-end crosstalk noise intensity exceeds the signal intensity of the object under test provided in an embodiment of the present application;

[0049] Figure 4 A flow chart of a laser ranging method provided in an embodiment of the present application;

[0050] Figure 5 A corrected dToF direct measurement time of flight histogram according to an embodiment of the present application;

[0051] Figure 6 A structural diagram of a laser ranging device provided in one embodiment of the present application;

[0052] Figure 7 A structural diagram of a laser ranging device provided in another embodiment of the present application. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] The core of this application is to provide a laser ranging method, device and medium for correcting laser ranging errors, thereby improving the accuracy of laser ranging.

[0055] In order to measure the distance of distant objects or objects located in complex environments, laser is usually used to measure the distance of the objects. Figure 1 A schematic diagram of a time-of-flight module distance measurement provided in an embodiment of the present application. When measuring distance, the distance between the time-of-flight module and the object 6 is measured. The time-of-flight module specifically includes a laser transmitter 1, a single photon avalanche diode 2, a time-to-digital converter 3, a lens 4 and a baffle 5. As long as the SPAD receives a photon, it can generate a current signal.

[0056] The principle of using the time-of-flight module to measure distance is as follows:

[0057] 1. VCSEL emits laser pulses and SPAD receives the pulses reflected from the object.

[0058] 2. TDC can record the time difference between SPAD receiving photons and VCSEL emitting lasers.

[0059] 3. According to the number of photons received by SPAD in different time periods, a histogram is calculated. Figure 2 A dToF direct measurement flight time histogram when the near-end crosstalk noise intensity is less than the signal intensity of the object under test is provided in an embodiment of the present application. Figure 2 As shown, the number of photons received by the SPAD is counted every 1ps starting from the time the VCSEL emits light, and is plotted as a histogram.

[0060] 4. Most of the photons emitted by VCSEL return when they hit the object being detected. Therefore, the time period t in the histogram when the largest number of photons is received is considered to be the flight time of the photons between the module and the object.

[0061] 5. Calculate the distance d between the module and the object based on the speed of light c as formula (1):

[0062] d=c*t / 2 (1)

[0063] 6. During the ranging process, the number of near-end photons will be larger due to near-end crosstalk and other reasons.

[0064] 7. Due to the loss of photons in the propagation process (VCSEL->object->SPAD), the number of photons at the far end will be smaller.

[0065] 8. Figure 3 A dToF direct measurement flight time histogram when the near-end crosstalk noise intensity exceeds the signal intensity of the object under test is provided in an embodiment of the present application. Figure 3 As shown in the figure, the peak at 1ps is a large number of photons generated by near-end crosstalk detected by SPAD; the peak at 150ps is a large number of photons returned by the object under test detected by SPAD. When the peak formed by near-end crosstalk is higher than the peak formed by the photons reflected back by the object, if you simply use the peak with the largest number of Counts to calculate the distance, you will get an incorrect distance:

[0066] 8.1 When t=1ps, d=c*t / 2=3*108(m / s)*1*10-12(s) / 2=0.15mm(error).

[0067] 8.2 When t = 150ps, d = c*t / 2 = 3*108(m / s)*150*10-12(s) / 2 = 22.5mm (correct).

[0068] In practice, there are many reasons for the generation of near-end crosstalk, which may come from the noise generated by the crosstalk inside the module, when a lens is installed outside the module, the lens has a certain degree of reflection, so that the photons reflected back by the lens and the crosstalk inside the module are superimposed to become noise, etc. A key technical problem of the time-of-flight ranging device is how to determine the flight time of light. The commonly used method at present is to record the time when the SPAD detects the photon through TDC, and the time when the largest number of photons is received is considered to be the flight time t of the light between the module and the object to be measured. When the flight time t of the light between the module and the object to be measured is confirmed, the distance between the module and the object to be measured can be calculated using formula (1). As described above, when the number of crosstalk photons received by the SPAD is the largest when near-end crosstalk exists, the obtained time t is not the flight time of the light between the module and the object to be measured. At this time, the calculated distance is also wrong, resulting in reduced accuracy in laser ranging.

[0069] It can be seen that in order to improve the accuracy of ranging, the laser ranging error needs to be calibrated. In this application, the laser ranging is calibrated before leaving the factory, and the actual data is subtracted from the calibration data to make the number of near-end photons less than the number of photons returned by the SPAD when detecting the target object, so as to obtain the correct flight time, and then obtain a more accurate distance between the module and the object based on the flight time; in addition, there may be factors such as the ambient light intensity during actual use that are different from the factory calibrated environment, resulting in the calibration data cannot completely and effectively offset noise such as near-end crosstalk. Therefore, in addition to calibrating the ranging before leaving the factory, this application also calibrates the ranging again during actual use to further improve the accuracy of ranging.

[0070] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 4 A flowchart of a laser ranging method provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the method includes:

[0071] S10: From the time the VCSEL starts to emit a laser pulse, the first calibration data within the acquisition time is obtained; wherein the first calibration data is the number of photons collected by the SPAD in each acquisition cycle within the acquisition time when there is no target object; the acquisition cycle is less than the acquisition time.

[0072] Since the distance measurement error caused by near-end crosstalk is to be reduced as much as possible, the number of collected photons needs to be obtained from the start of the VCSEL to emit laser pulses, and the number of photons received by the SPAD is obtained. First, the calibration data is obtained. The ranging device is calibrated before leaving the factory, and the calibration is performed when the module and lens and other components are assembled. The calibration data obtained after the factory calibration is called the first calibration data. The first calibration data describes the number of photons collected by the SPAD in each acquisition cycle. The value of each acquisition cycle is not limited, and preferably each acquisition cycle uses the same duration. In order to obtain the first calibration data method, the module is directed to an open area, where there is no target object (the object to be ranged is the target object), and the number of returned photons is ensured as much as possible that it is not the photons returned by the target object, that is, the number of photons obtained in each acquisition cycle due to near-end crosstalk is obtained. In this embodiment, the first calibration data within the acquisition duration is obtained from the start of the VCSEL emitting laser pulses. There is no limit on the value of the acquisition duration, and the maximum value of the acquisition duration is usually determined based on the performance of the module. In order to measure the distance to the target object, it is at least necessary to ensure that the laser pulse can hit the target object and the module can receive the photons returned after hitting the target object.

[0073] S11: Acquire actual data within the acquisition time since the VCSEL starts to emit a laser pulse; wherein the actual data is the number of photons collected by the SPAD in each acquisition cycle within the acquisition time when a target object is present.

[0074] The first calibration data is obtained in the above steps. In order to calibrate the actual data, it is necessary to obtain the actual data. The actual data is the number of photons collected by the SPAD in each acquisition cycle in the presence of a target object. Similarly, there is no limit on the value of each acquisition cycle, and preferably each acquisition cycle uses the same duration. In order to make the process of calibrating the actual data according to the first calibration data faster and more convenient, the acquisition cycles when obtaining the actual data are selected to be the same as the acquisition cycles for obtaining the first calibration data.

[0075] S12: Obtain a first difference between actual data in each acquisition cycle and first calibration data, and use the first difference as calibrated data.

[0076] S13: Determine the distance between the time-of-flight module and the target object according to the calibrated data.

[0077] After obtaining the first calibration data and the actual data, the first difference between the actual data of each acquisition period and the first calibration data is obtained respectively, and the first difference is the calibrated data obtained by calibrating the actual data according to the first calibration data. When determining the distance between the time-of-flight module and the target object according to the calibrated data, the time corresponding to the maximum number of photons in the calibrated data is selected, and this time is used as the flight time, so as to calculate the distance between the time-of-flight module and the target object according to formula (1), complete the laser ranging error correction, and obtain a more accurate laser ranging result.

[0078] The laser ranging method provided in this embodiment includes: starting from the VCSEL emitting a laser pulse, obtaining the first calibration data within the acquisition time; wherein the first calibration data is the number of photons collected by the SPAD in each acquisition period within the acquisition time when there is no target object; the acquisition period is less than the acquisition time; starting from the VCSEL emitting a laser pulse, obtaining the actual data within the acquisition time; wherein the actual data is the number of photons collected by the SPAD in each period within the acquisition time when there is a target object; obtaining the first difference between the actual data in each acquisition period and the corresponding first calibration data, and using the first difference as the calibrated data; determining the distance between the time-of-flight module and the target object according to the calibrated data. In this method, the calibration data is subtracted from the actual data, so that the number of near-end photons is less than the number of photons returned by the SPAD after detecting the target object, and the number of photons detected due to near-end crosstalk is avoided as much as possible, which leads to the occurrence of misjudgment when calculating the distance, thereby improving the accuracy of laser ranging.

[0079] In practice, as photons propagate, the number of far-end photons gradually decreases, and the present application solves the problem that the number of photons caused by near-end crosstalk is higher than the number of photons returned by the target object. Therefore, in order to obtain the first calibration data more quickly, a preferred implementation is that obtaining the first calibration data within the acquisition time includes:

[0080] Since the VCSEL starts to emit a laser pulse, first calibration data within a preset time length is acquired; wherein the preset time length is shorter than the acquisition time length, and the acquisition cycle is shorter than the preset time length.

[0081] The preset duration is determined based on the distance between the SPAD and the lens through which the laser pulse passes, and the preset duration is positively correlated with the distance from the SPAD to the lens. There is no limit on the value of the preset duration, and the preset duration does not need to be set very large. For example, it can be set to the duration for the photon to fly back and forth between the SPAD and the lens five times.

[0082] The self-emitting laser pulse provided in this embodiment only obtains the number of photons within a preset time length as the first calibration data. Since the number of photons at the far end will gradually decrease during the propagation of photons, it is not very meaningful to collect photons exceeding the preset time length. In addition, compared with obtaining the number of photons for the entire collection time, since the preset time length is shorter than the collection time length, collecting the number of photons for the preset time length is faster, and the difference between the actual data and the first calibration data can reduce the amount of calculation, thereby improving the efficiency of ranging calibration.

[0083] Based on the number of photons collected within the preset time as the first calibration data in the above embodiment, in order to measure the distance of the target object, a preferred implementation is that the actual data includes the first actual data within the preset time and the second actual data within the remaining time, and the remaining time is the time within the collection time excluding the preset time; determining the distance between the time-of-flight module and the target object according to the calibrated data includes:

[0084] Obtaining a second difference between the first actual data in each acquisition period and the corresponding first calibration data, and using the second difference as the first calibrated data within a preset time period;

[0085] Selecting a first moment corresponding to the maximum number of photons from the first calibrated data and the second actual data;

[0086] Get the first product result of the speed of light and the first moment;

[0087] Half of the first product result is used as the distance between the flight time module and the target object.

[0088] With the preset duration of 100ps, Figure 3 The ranging error caused by the near-end crosstalk is corrected. Figure 3 The acquisition period is 1ps and the acquisition duration is 400ps. The specific calibration process is as follows:

[0089] 1. Calibrate the distance measuring device before leaving the factory, and calibrate it after the module, lens and other components are assembled.

[0090] 2. Calibration steps:

[0091] 2.1. Point the module toward an open area (where there is no object to be measured).

[0092] 2.2. Record the data of the first 100ps, a total of 100 data, represented by C1 to C100.

[0093] 2.3. C1 to C100 are recorded in a read-only memory (ROM) as the first calibration data (which can be understood as factory calibration data).

[0094] 2.4. After leaving the factory, when the distance measuring device is used for distance measurement, the calibration data is read from the ROM.

[0095] 2.5. In actual use, the first actual data X1...X100 collected in the first 100ps is subtracted from the first calibration data C1...C100 to obtain the first calibrated data Y within 100ps, that is, Y=X-C, and then the Y data is used to calculate the distance.

[0096] 2.6. The Y data (within 100ps) and the X data within 100ps to 400ps should be stitched together and the distance calculated. The histogram of the stitched data is as follows: Figure 5 As shown, Figure 5 This is a corrected dToF direct measurement flight time histogram according to an embodiment of the present application.

[0097] 2.7. The purpose of subtracting the first calibration data is to make the maximum value of Y as much smaller as possible than the peak value of the object being measured.

[0098] 2.8. If some values ​​of Y decrease to negative numbers, treat them as 0;

[0099] 3. Combination Figure 5 After correction, the signal in the first 100ps is significantly weakened. At this time, the peak with the largest number of counts (t=150ps) is used to calculate the distance, and a correct distance will be obtained:

[0100] When t=150ps, d=c*t / 2=3*108(m / s)*150*10-12(s) / 2=22.5mm.

[0101] The first calibration data according to the factory preset time provided in this embodiment realizes the calibration of actual data, thereby improving the accuracy of laser ranging.

[0102] In the above, the laser rangefinder is calibrated before leaving the factory. However, in actual use, the ambient light intensity of the use environment is different from that of the factory calibration. The first calibration data obtained in the above cannot completely and effectively offset noise such as near-end crosstalk, and there may be fingerprints, oil stains, etc. on the lens, which causes the reflectivity of the lens to change, and the original first calibration data is no longer applicable. Therefore, in order to solve interference factors such as different ambient light (including oil stains), it is necessary to recalibrate the first calibration data during actual use. When recalibrating, the preferred implementation is that after obtaining the actual data within the acquisition time, the laser rangefinder method also includes:

[0103] Determine the second moment corresponding to the maximum number of photons based on actual data;

[0104] Determine whether the second moment is within the remaining time;

[0105] If yes, obtaining a first ratio of the first actual data in each acquisition period to the corresponding first calibration data;

[0106] Obtaining the product of each first ratio and the corresponding first calibration data, and using each product as the second calibration data;

[0107] Obtaining a third difference between the first actual data in each acquisition period and the corresponding second calibration data, and using the third difference as the second calibrated data within a preset time period;

[0108] Selecting a third moment corresponding to the maximum number of photons from the second calibrated data and the second actual data;

[0109] When the second moment and the third moment are the same moment, obtaining a second product result of the speed of light and the second moment or the third moment;

[0110] Half of the second product result is used as the distance between the flight time module and the target object.

[0111] When the ambient light is particularly strong, or the module collides and causes a slight change in structure, resulting in an increase in the crosstalk signal, the actual data X may be very large and cannot be predicted at the factory, so the calibration parameters need to be adjusted automatically. Specifically, the second moment corresponding to the maximum number of photons is determined based on the actual data; if the second moment is within the remaining time, it means that the object being measured is far away from the ranging device. At this time, it is considered that the photons collected within the preset time are not returned by the object being measured, but are photons generated by interference factors such as near-end crosstalk, glass lenses, oil stains, and ambient light, which are noise. Figure 5 When the peak in appears outside 100ps, it is considered that the photons collected within 100ps are not returned by the measured object but are returned by noise, and the second calibration data W1 to W100 are calculated.

[0112] The process of calculating the first ratio R is shown in formula (2):

[0113] Ri=Xi / Ci (2)

[0114] The process of calculating the second calibration data W according to the first ratio R is shown in formula (3):

[0115] Wi=Ci*Ri (3)

[0116] The second calibrated data Y' is calculated according to the second calibration data W of the preset time length and the first actual data. The calculation process is shown in formula (4):

[0117] Yi'=Xi-Wi (4)

[0118] Taking the preset duration of 100ps as an example, R1 to R100 are calculated by formula (2), the second calibration data W1 to W100 are calculated by formula (3), and Y1' to Y100' are calculated by formula (4); the third moment corresponding to the maximum number of photons is selected from Y1' to Y100' and X101 to X400. When the third moment is the same as the previous second moment, the second moment or the third moment is substituted into formula (1) to calculate the distance between the flight time module and the target object, complete the laser ranging error correction, and obtain a more accurate laser ranging result.

[0119] In the method provided in this embodiment, based on the calibration before leaving the factory, recalibration is performed during actual use, so as to reduce the influence of ambient light (including oil stains) and the like on the ranging accuracy as much as possible.

[0120] The above embodiment is to recalibrate the first calibration data within the preset time length. In practice, in order to improve the efficiency of laser ranging, a preferred implementation is that after determining that the second moment is within the remaining time length, before obtaining the first ratio of the first actual data in each acquisition cycle to the corresponding first calibration data, the laser ranging method further includes:

[0121] Obtaining a first maximum number of photons from the first actual data and obtaining a second maximum number of photons from the first calibration data;

[0122] obtaining a second ratio of the first maximum number of photons to the second maximum number of photons;

[0123] If the second ratio is greater than or equal to the threshold, the process proceeds to a step of acquiring a first ratio of the first actual data in each acquisition cycle to the corresponding first calibration data.

[0124] In the first actual data X1 to X100, the maximum Counts number N1 is recorded, and the maximum value in the first calibration data C1 to C100 is taken as N2. When the ratio of N1 to N2 is greater than or equal to the threshold, it means that there is a large difference between the environment during use and the calibration light environment before leaving the factory, so the first calibration data needs to be recalibrated to obtain the second calibration data. Usually, the threshold is selected as 1.2, that is, the second calibration is performed only when the second ratio is greater than or equal to 1.2.

[0125] The present embodiment provides that the second calibration is performed only when the second ratio is greater than or equal to the threshold value. Compared with the method of directly performing the second calibration when in use, if the light environment during use is not much different from the calibration light environment before leaving the factory, it means that the first calibration data can be used. If the first calibration data is calibrated again, the efficiency of ranging will be reduced.

[0126] In implementation, in order to facilitate the user to understand whether the emitted laser pulse hits the target object and to find the flight time, a preferred implementation is that the laser ranging method further includes:

[0127] When the laser pulse emitted by the VCSEL hits the target object, prompt information indicating that the target object has been hit is output and / or the time corresponding to the hit of the target object is recorded.

[0128] There is no limitation on the method and content of the prompt information, as long as it can prompt the user that the emitted laser pulse hits the target object. In addition to outputting the prompt information, the moment of hitting the target object can also be recorded. The distance between the flight time module and the target object can be estimated based on the actual recorded moment. The estimated distance can be compared with the distance calculated by this application to analyze the accuracy of the distance measurement of this application.

[0129] In the above embodiments, the laser distance measurement method is described in detail, and the present application also provides embodiments corresponding to the laser distance measurement device. It should be noted that the present application describes the embodiments of the device part from two perspectives, one is based on the functional module perspective, and the other is based on the hardware perspective.

[0130] Figure 6 A structural diagram of a laser distance measurement device provided in one embodiment of the present application. This embodiment is based on the perspective of functional modules and includes:

[0131] The first acquisition module 10 is used to acquire the first calibration data within the acquisition time length since the VCSEL starts to emit the laser pulse; wherein the first calibration data is the number of photons collected by the SPAD in each acquisition cycle within the acquisition time length when there is no target object; the acquisition cycle is less than the acquisition time length;

[0132] The second acquisition module 11 is used to acquire actual data within the acquisition time length since the VCSEL starts to emit a laser pulse; wherein the actual data is the number of photons collected by the SPAD in each acquisition cycle within the acquisition time length in the presence of a target object;

[0133] A third acquisition module 12 is used to acquire a first difference between the actual data in each acquisition period and the corresponding first calibration data, and use the first difference as the calibrated data;

[0134] The determination module 13 is used to determine the distance between the time-of-flight module and the target object according to the calibrated data.

[0135] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, which will not be repeated here.

[0136] In the laser ranging device provided in this embodiment, the first calibration data within the acquisition time is acquired by the first acquisition module from the start of the VCSEL emitting the laser pulse; wherein the first calibration data is the number of photons collected by the SPAD in each acquisition cycle within the acquisition time when there is no target object; the acquisition cycle is less than the acquisition time; the actual data within the acquisition time is acquired by the second acquisition module from the start of the VCSEL emitting the laser pulse; wherein the actual data is the number of photons collected by the SPAD in each acquisition cycle within the acquisition time when there is a target object; the first difference between the actual data in each acquisition cycle and the corresponding first calibration data is acquired by the third acquisition module, and the first difference is used as the calibrated data; the distance between the time-of-flight module and the target object is determined by the determination module according to the calibrated data. In the device, the calibration data is subtracted from the actual data, so that the number of near-end photons is less than the number of photons returned by the SPAD when detecting the target object, and the number of photons detected due to near-end crosstalk is avoided as much as possible, which leads to the occurrence of misjudgment when calculating the distance, thereby improving the accuracy of laser ranging.

[0137] Figure 7 This is a structural diagram of a laser distance measurement device provided in another embodiment of the present application. This embodiment is based on the hardware perspective, such as Figure 7 As shown, the laser ranging device includes:

[0138] A memory 20, used for storing computer programs;

[0139] The processor 21 is used to implement the steps of the laser ranging method mentioned in the above embodiment when executing the computer program.

[0140] The laser ranging device provided in this embodiment may include but is not limited to a smart phone, a tablet computer, a laptop computer or a desktop computer.

[0141] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0142] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used to store the following computer program 201, wherein, after the computer program is loaded and executed by the processor 21, the relevant steps of the laser ranging method disclosed in any of the aforementioned embodiments can be implemented. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. The data 203 may include, but is not limited to, the data involved in the above-mentioned laser ranging method, etc.

[0143] In some embodiments, the laser ranging device may further include a display screen 22 , an input / output interface 23 , a communication interface 24 , a power supply 25 , and a communication bus 26 .

[0144] Those skilled in the art will understand that Figure 7 The structure shown in the figure does not constitute a limitation on the laser ranging device, and may include more or fewer components than those shown in the figure.

[0145] The laser ranging device provided in the embodiment of the present application includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the following method: the laser ranging method has the same effect as above.

[0146] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps recorded in the above method embodiment are implemented.

[0147] It is understandable that if the method in the above embodiment 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 technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0148] The computer-readable storage medium provided in the present application includes the above-mentioned laser ranging method, and the effect is the same as above.

[0149] The above is a detailed introduction to a laser ranging method, device and medium provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0150] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A laser ranging method, characterized in that: include: Starting from the laser emitter emitting a laser pulse, the first calibration data within the acquisition time is acquired; wherein the first calibration data is the number of photons collected by the single-photon avalanche diode in each acquisition cycle within the acquisition time when there is no target object; the acquisition cycle is less than the acquisition time; acquiring the first calibration data within the acquisition time includes: starting from the laser emitter emitting a laser pulse, acquiring the first calibration data within a preset time; the preset time is less than the acquisition time, and the acquisition cycle is less than the preset time; Since the laser emitter starts to emit a laser pulse, actual data within the acquisition time is acquired; wherein the actual data is the number of photons collected by the single-photon avalanche diode in each of the acquisition cycles within the acquisition time when the target object is present; the actual data includes first actual data within the preset time and second actual data within the remaining time, wherein the remaining time is the time within the acquisition time excluding the preset time; Acquire a second difference between the first actual data and the corresponding first calibration data in each acquisition period, and use the second difference as the first calibrated data within the preset time period; Selecting a first moment corresponding to the maximum number of photons from the first calibrated data and the second actual data; Obtaining a first product result of the speed of light and the first moment; A half of the first product result is used as the distance between the flight time module and the target object.

2. The laser distance measurement method according to claim 1, characterized in that: The preset time length is determined according to the distance between the single photon avalanche diode and the lens through which the laser pulse passes, and the preset time length is positively correlated with the distance from the single photon avalanche diode to the lens.

3. The laser ranging method according to claim 2, characterized in that: After obtaining the actual data within the acquisition time, the method further includes: Determine, according to the actual data, a second moment corresponding to when the number of photons is the largest; Determining whether the second moment is within the remaining time; If yes, obtaining a first ratio of the first actual data in each acquisition period to the corresponding first calibration data; Obtaining a product of each of the first ratios and the corresponding first calibration data, and using each of the products as second calibration data; Acquire a third difference between the first actual data and the corresponding second calibration data in each acquisition period, and use the third difference as the second calibrated data within the preset time period; Selecting a third moment corresponding to the maximum number of photons from the second calibrated data and the second actual data; When the second moment and the third moment are the same moment, obtaining a second product result of the speed of light and the second moment or the third moment; A half of the second product result is used as the distance between the flight time module and the target object.

4. The laser distance measurement method according to claim 3, characterized in that: After determining that the second moment is within the remaining time, and before acquiring a first ratio of the first actual data to the corresponding first calibration data in each acquisition cycle, the method further includes: Acquire a first maximum number of photons from the first actual data and acquire a second maximum number of photons from the first calibration data; Obtaining a second ratio of the first maximum number of photons to the second maximum number of photons; If the second ratio is greater than or equal to the threshold, the process proceeds to the step of obtaining the first ratio of the first actual data in each acquisition cycle to the corresponding first calibration data.

5. The laser distance measurement method according to any one of claims 1 to 4, characterized in that: The method further comprises: When the laser emitter emits a laser pulse and hits the target object, prompt information indicating that the target object has been hit is output and / or a time corresponding to the hit of the target object is recorded.

6. A laser distance measuring device, characterized in that: include: A first acquisition module is used to acquire first calibration data within an acquisition time length starting from the laser emitter emitting a laser pulse; wherein the first calibration data is the number of photons collected by the single-photon avalanche diode in each acquisition cycle within the acquisition time length in the absence of a target object; the acquisition cycle is shorter than the acquisition time length; the first acquisition module is specifically used to: acquire the first calibration data within a preset time length starting from the laser emitter emitting a laser pulse; the preset time length is shorter than the acquisition time length, and the acquisition cycle is shorter than the preset time length; A second acquisition module is used to acquire actual data within the acquisition time length since the laser emitter starts to emit a laser pulse; wherein the actual data is the number of photons collected by the single-photon avalanche diode in each of the acquisition cycles within the acquisition time length when the target object exists; the actual data includes first actual data within the preset time length and second actual data within the remaining time length, and the remaining time length is the time length within the acquisition time length excluding the preset time length; Acquire a second difference between the first actual data and the corresponding first calibration data in each acquisition period, and use the second difference as the first calibrated data within the preset time period; Selecting a first moment corresponding to the maximum number of photons from the first calibrated data and the second actual data; Obtaining a first product result of the speed of light and the first moment; A half of the first product result is used as the distance between the flight time module and the target object.

7. A laser distance measuring device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the laser ranging method as claimed in any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the laser ranging method according to any one of claims 1 to 5 are implemented.

Images