CN115469320A - Laser ranging method, device and medium - Google Patents

Abstract

The application discloses a method, a device and a medium for laser ranging, and relates to the field of optics. The method comprises the following steps: acquiring first calibration data within an acquisition duration under the condition that a target object does not exist; acquiring actual data within the acquisition duration under the condition that a target object exists; acquiring a first difference value between actual data in each acquisition period and corresponding first calibration data, and taking the first difference value as data after the first calibration data is calibrated; and determining the distance between the time-of-flight module and the target object according to the data after the first calibration. In the method, the actual data is used for subtracting the calibration data, so that the number of the photons at the near end is smaller than the number of the photons returned by the single photon avalanche diode when the target object is detected, the phenomenon that the number of the detected photons is higher than the number of the photons returned by the target object due to near-end crosstalk, the misjudgment caused during distance calculation is avoided as much as possible, and the accuracy of laser ranging is improved.

Description

Method, device and medium for laser ranging

technical field

The present application relates to the field of optics, in particular to a method, device and medium for laser ranging.

Background technique

In order to measure the distance of a distant object or an object located in a complex environment, a laser is usually used to measure the distance of the object. For example, a time-of-flight model composed of a vertical cavity surface emitting laser (Vertical Cavity Surface Emitting Laser, VCSEL), a single photon avalanche diode (Single Photon Avalanche Diode, SPAD) and a time-to-digital converter (TDC) Group.

During the ranging process, the VCSEL emits laser pulses, and the SPAD receives the pulses reflected from the object. The TDC records the time difference between the photons received by the SPAD and the laser emitted by the VCSEL, and the moment when the maximum number of photons received by the SPAD is considered as the moment from the module to the object. The time of flight between them, and then calculate the distance between the module and the object according to the speed of light and the time of flight. Due to reasons such as near-end crosstalk (including module internal light ring crosstalk and module external light environment crosstalk), 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 back by the object, If you simply use the peak with the largest number of photons to calculate the distance, you will get a wrong distance, making the measured distance of the object inaccurate.

It can be seen that how to improve the accuracy of laser ranging is a technical problem urgently needed to be solved by those skilled in the art.

Contents of the invention

The purpose of this application is to provide a method, device and medium for laser distance measurement, which are used to correct laser distance measurement errors, thereby improving the accuracy of laser distance measurement.

In order to solve the above technical problems, this application provides a method for laser ranging, including:

Since the laser transmitter emits laser pulses, the first calibration data within the acquisition period is obtained; wherein, the first calibration data is each acquisition of the single photon avalanche diode within the acquisition period in the absence of a target object The number of photons collected periodically; the collection period is shorter than the collection duration;

Since the laser transmitter emits laser pulses, the actual data within the acquisition time period is acquired; wherein the actual data is the single photon avalanche diode in the acquisition time period under the condition that the target object exists The number of photons collected in each of the collection periods;

Acquiring a first difference between the actual data and the corresponding first calibration data in each of the collection periods, and using the first difference as calibrated data;

The distance between the time-of-flight module and the target object is determined according to the calibrated data.

Preferably, said acquiring the first calibration data within the collection time includes:

Acquiring the first calibration data within a preset time period since the laser emitter emits a laser pulse; wherein the preset time period is shorter than the collection time period, and the collection period is shorter than the preset time period.

Preferably, the actual data includes the first actual data within the preset duration and the second actual data within the remaining duration, and the remaining duration is a duration within the collection duration other than the preset duration; The determination of the distance between the time-of-flight module and the target object according to the calibrated data includes:

Acquiring a second difference between the first actual data and the corresponding first calibration data in each of the collection periods, and using the second difference as the first calibrated value within the preset time length data;

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

Obtain the first product result of the speed of light and the first moment;

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

Preferably, the preset duration is determined according to the distance between the single photon avalanche diode and the lens through which the laser pulse passes, and the preset duration is positive to the distance between the single photon avalanche diode and the lens relevant.

Preferably, after the acquisition of the actual data within the collection period, the method further includes:

determining the second moment corresponding to when the number of photons is the largest according to the actual data;

judging whether the second moment is within the remaining duration;

If so, acquiring a first ratio between the first actual data and the corresponding first calibration data in each of the collection periods;

Obtain the product of each of the first ratios and the corresponding first calibration data, and use each of the products as the second calibration data;

Acquiring a third difference between the first actual data and the corresponding second calibration data in each of the collection periods, and using the third difference as the second calibrated value within the preset time length data;

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

If the second moment and the third moment are the same moment, obtain a second product result of the speed of light and the second moment or the third moment;

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

Preferably, after it is determined that the second moment is within the remaining duration, before acquiring the first ratio between the first actual data and the corresponding first calibration data in each of the collection periods, The method also includes:

obtaining a first maximum number of photons from said first actual data and a second maximum number of photons from said 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, enter the step of acquiring the first ratio between the first actual data and the corresponding first calibration data in each of the collection periods.

Preferably, the method also includes:

When the laser pulse emitted by the laser emitter collides with the target object, output prompt information representing the colliding with the target object and/or record the corresponding moment of colliding with the target object.

In order to solve the above technical problems, the present application also provides a laser ranging device, including:

The first acquisition module is used to acquire the first calibration data within the acquisition time period since the laser transmitter emits the laser pulse; wherein, the first calibration data is the single photon avalanche diode in the absence of the target object. The number of photons collected in each collection period within the collection period; the collection period is less than the collection period;

The second acquisition module is configured to acquire the actual data within the acquisition duration since the laser transmitter emits the laser pulse; wherein the actual data is the single photon avalanche in the presence of the target object the number of photons collected by the diode in each of the collection periods within the collection period;

A third acquiring module, configured to acquire a first difference between the actual data and the corresponding first calibration data in each of the acquisition periods, and use the first difference as calibrated data;

A determining module, configured to determine the distance between the time-of-flight module and the target object according to the calibrated data.

In order to solve the above technical problems, the present application also provides a laser ranging device, including:

memory for storing computer programs;

The processor is configured to realize the steps of the above-mentioned laser ranging method when executing the computer program.

In order to solve the above-mentioned 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-mentioned laser ranging method are realized .

The laser ranging method provided by the present application includes: starting from the laser transmitter emitting laser pulses, obtaining the first calibration data within the acquisition time; wherein, the first calibration data is a single photon in the absence of a target object The number of photons collected by the avalanche diode in each acquisition period within the acquisition period; the acquisition period is less than the acquisition period; since the laser transmitter emits laser pulses, the actual data within the acquisition period is obtained; where the actual data is in the presence of the target object Next, the number of photons collected by the single photon avalanche diode in each period of the acquisition period; the first difference between the actual data in each acquisition period and the corresponding first calibration data is obtained, and the first difference is used as the calibrated Data; determine the distance between the time-of-flight module and the target object based on 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 detected photons caused by near-end crosstalk is avoided as much as possible. The number of photons returned by the target object will lead to misjudgment during distance calculation and improve the accuracy of laser ranging.

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 the effect is the same as above.

Description of drawings

In order to illustrate the embodiments of the present application more clearly, the following will briefly introduce the accompanying drawings used in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. As far as people are concerned, other drawings can also be obtained based on these drawings on the premise of not paying creative work.

Fig. 1 is a schematic diagram of a time-of-flight module ranging provided by an embodiment of the present application;

Fig. 2 is a dToF direct measurement time-of-flight histogram when the near-end crosstalk noise intensity is less than the signal intensity of the measured object provided by the embodiment of the present application;

Fig. 3 is a dToF direct measurement time-of-flight histogram when the near-end crosstalk noise strength exceeds the signal strength of the measured object provided by the embodiment of the present application;

FIG. 4 is a flow chart of a laser ranging method provided in an embodiment of the present application;

FIG. 5 is a corrected dToF direct measurement time-of-flight histogram according to an embodiment of the present application;

FIG. 6 is a structural diagram of a laser ranging device provided by an embodiment of the present application;

FIG. 7 is a structural diagram of a laser ranging device provided in another embodiment of the present application.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of this application.

The core of the present application is to provide a method, device and medium for laser distance measurement, which are used to correct laser distance measurement errors, thereby improving the accuracy of laser distance measurement.

In order to measure the distance of a distant object or an object located in a complex environment, a laser is usually used to measure the distance of the object. FIG. 1 is a schematic diagram of a time-of-flight module ranging provided by an embodiment of the present application. What is measured during ranging is the distance between the time-of-flight module and the object 6 . 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 a SPAD receives a photon, it can generate a current signal.

The principle of distance measurement using the time-of-flight module is as follows:

1. The VCSEL emits laser pulses, and the SPAD receives the pulses reflected from the object.

2. The TDC can record the time difference between the photon received by the SPAD and the laser emitted by the VCSEL.

3. According to the number of photons received by the SPAD in different time periods, the histogram is calculated. Figure 2 is a dToF direct measurement time-of-flight when the near-end crosstalk noise intensity is less than the signal intensity of the measured object provided by the embodiment of the present application. histogram. As shown in Figure 2, statistics are started when the VCSEL emits light, and the number of photons received by the SPAD is counted every 1ps, and drawn as a histogram.

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

5. Calculate the distance d between the module and the object according to the speed of light c as formula (1):

d=c*t/2 (1)

6. During the ranging process, due to near-end crosstalk and other reasons, the number of near-end photons will be too large.

7. Due to the loss of photons in the propagation process (VCSEL->object->SPAD), the number of far-end photons will be relatively small.

8. FIG. 3 is a dToF direct measurement time-of-flight histogram when the near-end crosstalk noise intensity exceeds the signal intensity of the object under test provided by the embodiment of the present application. As shown in Figure 3, the peak at 1ps is a large number of photons generated by the near-end crosstalk detected by the SPAD; the peak at 150ps is a large number of photons returned by the object detected by the SPAD. When the peak formed by the 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:

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

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

In practice, there are many reasons for near-end crosstalk. It may come from the noise generated by the internal crosstalk of the module. When the lens is installed outside the module, the lens has a certain degree of reflection, so that the photons reflected by the lens and the crosstalk in 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. At present, the commonly used method is to record the time when the SPAD detects photons through TDC, and the time when the number of photons is received is the largest, which is considered to be the flight time t of light between the module and the measured object. When the flight time between objects is t, the distance between the module and the measured object can be obtained by using the formula (1). As described above, when there is near-end crosstalk and the number of crosstalk photons received by the SPAD is the largest, the obtained time t is not the flight time of light between the module and the measured object, and the calculated distance at this time is also wrong, resulting in Reduced accuracy when measuring laser distances.

It can be seen that in order to improve the accuracy of ranging, it is necessary to calibrate the laser ranging error. In this application, the laser ranging is calibrated before leaving the factory, and the actual data is used to subtract the calibration data so that the number of near-end photons is less than the number of photons returned by the SPAD when it detects the target object, thereby obtaining the correct flight time. A more accurate distance between the module and the object can be obtained according to the time of flight; in addition, there may be factors such as the actual use environment and the factory-calibrated ambient light intensity, which may cause the calibration data to be unable to completely and effectively offset noise such as near-end crosstalk Therefore, in addition to calibrating the distance measurement before leaving the factory, the present application also calibrates the distance measurement again during actual use, so as to further improve the accuracy of the distance measurement.

In order to enable those skilled in the art to better understand the solution of the present application, the present application will be further described in detail below in conjunction with the drawings and specific implementation methods. Fig. 4 is a flow chart of a method for laser ranging provided in the embodiment of the present application. As shown in Fig. 4, the method includes:

S10: starting from the VCSEL emitting laser pulses, acquiring the first calibration data within the acquisition duration; wherein, the first calibration data is the number of photons collected by the SPAD in each acquisition period within the acquisition duration when no target object exists; The acquisition period is less than the acquisition duration.

Since the ranging error caused by the near-end crosstalk is to be reduced as much as possible, the number of photons collected needs to be obtained from the start of the laser pulse emitted by the VCSEL to obtain the number of photons received by the SPAD. Get the calibration data first. The distance measuring device is calibrated before leaving the factory, and the calibration is performed when the components such as the module and the lens are assembled, and 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 period, and there is no limitation on the value of each acquisition period, preferably, each acquisition period adopts the same duration. In order to obtain the first calibration data mode, point the module towards an open area, and there is no target object at this time (the object that needs to be measured is the target object), and try to ensure that the number of photons returned is not the photons returned by the target object, that is, to obtain The number of photons acquired at each acquisition cycle due to near-end crosstalk. In this embodiment, the first calibration data within the acquisition time period is obtained from the VCSEL emitting the laser pulse. There is no limit to the value of the collection time, and the maximum value of the collection time is usually determined according to the performance of the module. In order to be able to measure the distance of the target object, at least ensure that the laser pulse can hit the target object and the module can receive the photons returned after hitting the target object.

S11: Acquire the actual data within the acquisition period since the VCSEL emits the laser pulse; where the actual data is the number of photons collected by the SPAD in each acquisition period within the acquisition period when the target object exists.

The first calibration data is obtained in the above steps. In order to calibrate against actual data, it is necessary to acquire actual data. The actual data is the number of photons collected by the SPAD in each acquisition period when there is a target object. Similarly, there is no limitation on the value of each acquisition period, and preferably each acquisition period adopts the same duration. In order to make the process of calibrating the actual data according to the first calibration data faster and more convenient, each acquisition period when acquiring the actual data is selected to be the same as each acquisition period for acquiring the first calibration data.

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

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

After the first calibration data and the actual data are obtained, the first difference between the actual data and the first calibration data of each acquisition cycle is respectively obtained, and the first difference is the calibrated value obtained by calibrating the actual data according to the first calibration data. The data. When determining the distance between the time-of-flight module and the target object according to the calibrated data, select the time corresponding to the maximum number of photons in the calibrated data, and use this time as the flight time, so as to calculate the flight time according to the formula (1). The distance between the time module and the target object is completed, and the laser ranging error correction is completed to obtain more accurate laser ranging results.

The method for laser ranging provided in this embodiment includes: starting from the VCSEL to emit laser pulses, and obtaining the first calibration data within the acquisition time; wherein, the first calibration data is when there is no target object, the SPAD is collecting The number of photons collected in each acquisition period within the duration; the acquisition period is less than the acquisition duration; since the VCSEL emits laser pulses, the actual data within the acquisition duration is obtained; where the actual data is the SPAD during the acquisition duration when there is a target object The number of photons collected in each period in each acquisition period; obtain the 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; determine the flight according to the calibrated data The distance between the time module and the target object. 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 when the target object is detected, and the number of detected photons is higher than the target object due to near-end crosstalk as much as possible. The number of returned photons will lead to the occurrence of misjudgment during distance calculation, improving the accuracy of laser ranging.

In practice, the number of far-end photons will gradually decrease during the propagation of photons, and this 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 One calibration data, in a preferred embodiment, obtaining the first calibration data within the collection time includes:

The first calibration data within a preset time period is acquired since the VCSEL emits a laser pulse; wherein, the preset time period is shorter than the collection time period, and the collection period is shorter than the preset time period.

The preset duration is determined according to 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 limitation on the value of the preset duration, and the preset duration does not need to be set to be very large, for example, it may be set as the duration that photons fly back and forth between the SPAD and the lens five times.

The self-emission laser pulse provided in this embodiment only acquires the number of photons within the 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, if the collection exceeds the preset time length In addition, compared with the number of photons acquired for the entire acquisition time, since the preset time is shorter than the acquisition time, the number of photons collected for the preset time is faster, and the actual data and The difference of the first calibration data can reduce the amount of calculation and improve the efficiency of distance measurement calibration.

On the basis of collecting the number of photons within the preset time length in the above embodiment as the first calibration data, in order to measure the distance of the target object, the preferred implementation mode is that the actual data includes the first actual data within the preset time length and The second actual data within the remaining duration, the remaining duration is the duration of the acquisition duration except the preset duration; determining the distance between the time-of-flight module and the target object according to the calibrated data includes:

Acquiring a second difference between the first actual data and the corresponding first calibration data in each acquisition cycle, and using the second difference as the first calibrated data within a preset time length;

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

Obtain the result of the first product of the speed of light and the first moment;

Take half of the result of the first product as the distance between the time-of-flight module and the target object.

The ranging error caused by the near-end crosstalk in Figure 3 is corrected with the preset time length of 100 ps. In Figure 3, the acquisition period is 1 ps and the acquisition time is 400 ps. The specific calibration process is as follows:

1. Calibrate the distance measuring device before leaving the factory, and calibrate when the components such as the module and the lens are assembled

2. Calibration steps:

2.1. Turn the module towards an open area (there is no object to be measured at this time).

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

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).

2.4. After leaving the factory, when the distance measuring device is used for distance measurement, it reads the calibration data from the ROM.

2.5. Subtract the first calibration data C1...C100 from the first actual data X1...X100 collected in the first 100 ps during actual use to obtain the first calibrated data Y within 100 ps, that is, Y=X–C, and then Use the Y data to calculate the distance.

2.6. The Y data (within 100 ps) and the X data within 100 ps to 400 ps must be stitched together to calculate the distance. The histogram of the spliced data is shown in Figure 5, and Figure 5 is a corrected dToF of the embodiment of the present application Direct measurement of time-of-flight histograms.

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

2.8. If some values of Y are reduced to negative numbers, treat them as 0;

3. Combined with Figure 5, after correction, the signal in the first 100ps is obviously weakened. At this time, use the peak with the largest Counts (t=150ps) to calculate the distance, and a correct distance will be obtained:

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

The first calibration data provided in this embodiment according to the preset duration before leaving the factory realizes the calibration of actual data and improves the accuracy of laser ranging.

In the above, the laser ranging is calibrated before leaving the factory, but the actual use environment is different from the factory-calibrated ambient light intensity and other factors. The first calibration data obtained above cannot completely and effectively offset noise such as near-end crosstalk. In addition, there may be fingerprints, oil stains, etc. on the lens, resulting in changes in the reflectivity of the lens, and the original first calibration data is no longer applicable. Therefore, in order to solve interference factors such as different ambient lights (including oil pollution), it is necessary to recalibrate the first calibration data during actual use. When recalibrating, a preferred implementation is that, after acquiring the actual data within the acquisition period, the method for laser ranging also includes:

Determining the second moment corresponding to when the number of photons is the largest according to the actual data;

Determine whether the second moment is within the remaining duration;

If yes, then acquire the first ratio of the first actual data and the corresponding first calibration data in each acquisition cycle;

Obtain the product of each first ratio and the corresponding first calibration data, and use each product as the second calibration data;

Acquiring a third difference between the first actual data and the corresponding second calibration data in each collection period, and using the third difference as the second calibrated data within the preset time length;

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

In the case that the second moment and the third moment are the same moment, obtain the second product result of the speed of light and the second moment or the third moment;

Take half of the result of the second product as the distance between the time-of-flight module and the target object.

When the ambient light is particularly strong, or the structure of the module is slightly changed due to a collision, the crosstalk signal is enhanced, and the actual data X may be very large, which 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 according to the actual data; if the second moment is within the remaining duration, it means that the measured object is far away from the distance measuring device, and it is considered that the photons collected within the preset duration are not What is returned by the measured object is the photons generated by interference factors such as near-end crosstalk, glass lens, oil pollution, and ambient light, which is noise. As shown in Figure 5, when the peak appears outside 100 ps, it is considered that the photons collected within 100 ps are not returned by the measured object, but returned by noise, and then the second calibration data W1 to W100 are calculated.

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

Ri=Xi/Ci (2)

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

Wi=Ci*Ri (3)

Calculate the second calibrated data Y' according to the second calibration data W of the preset duration and the first actual data, and the calculation process is shown in formula (4):

Yi'=Xi-Wi (4)

Taking the preset time length of 100ps as an example, calculate R1 to R100 through formula (2), calculate the second calibration data W1 to W100 through formula (3), and calculate Y1' to Y100' through formula (4); from Y1 From 'to Y100' and X101 to X400, select the third moment corresponding to the time when the number of photons is the largest, and when the third moment is the same as the previous second moment, substitute the second moment or the third moment into the formula (1) Calculate the distance between the time-of-flight module and the target object, complete the laser ranging error correction, and obtain more accurate laser ranging results.

In the method provided in this embodiment, on the basis of calibration before leaving the factory, calibration is performed again during actual use, so as to minimize the impact of ambient light (including oil pollution) on the ranging accuracy.

The above-mentioned embodiment is to recalibrate the first calibration data within the preset time length. In practice, in order to improve the efficiency of laser ranging, the preferred implementation mode is to obtain each collected data after it is determined that the second moment is within the remaining time length. Before the first ratio of the first actual data in the period to the corresponding first calibration data, the method for laser ranging further includes:

obtaining a first maximum number of photons from the first actual data and a second maximum number of photons from the first calibration data;

obtaining a second ratio of the first largest number of photons to the second largest number of photons;

If the second ratio is greater than or equal to the threshold, enter the step of obtaining the first ratio of the first actual data and the corresponding first calibration data in each acquisition period.

In the first actual data X1 to X100, record the maximum number of Counts N1, and in the first calibration data C1 to C100, the maximum value is taken as N2. When the ratio of N1 to N2 is greater than or equal to the threshold value, it means that the environment during use is different from the factory There is a large difference in the previous calibration light environment, so the first calibration data needs to be calibrated again to obtain the second calibration data. Usually, the threshold value is 1.2, that is, the second calibration is performed only when the second ratio is greater than or equal to 1.2.

In this embodiment, 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 during use, such as the light environment during use is different from that before leaving the factory. The calibration light environment is not much different, which means that the first calibration data can be used. If the first calibration data is recalibrated, the efficiency of distance measurement will be reduced.

In implementation, in order to facilitate the user to know whether the emitted laser pulse hits the target object and to find the time of flight, the preferred embodiment is that the method of laser ranging also includes:

When the VCSEL emits a laser pulse that collides with the target object, it outputs prompt information for representing the colliding with the target object and/or records the corresponding moment of colliding with the target object.

There are no limitations on the manner and content of the prompt information, as long as the user can be prompted that the emitted laser pulse hits the target object. In addition to outputting prompt information, it is also possible to record the time when the target object is encountered. According to the actual recorded time, the distance between the time-of-flight module and the target object can be estimated, and the estimated distance can be compared with the one calculated by this application. The distance is compared to analyze the accuracy of the distance measurement of this application.

In the foregoing embodiments, the laser ranging method is described in detail, and the present application also provides corresponding embodiments of the laser ranging device. It should be noted that this application describes the embodiments of the device part from two perspectives, one is based on the perspective of functional modules, and the other is based on the perspective of hardware.

FIG. 6 is a structural diagram of a laser ranging device provided by an embodiment of the present application. This embodiment is based on the perspective of functional modules, including:

The first acquisition module 10 is used to obtain the first calibration data in the acquisition period since the laser pulse is emitted by the VCSEL; wherein the first calibration data is each acquisition period of the SPAD in the acquisition period in the absence of a target object The number of collected photons; the collection period is less than the collection time;

The second acquisition module 11 is used to start from the VCSEL to emit laser pulses to obtain the actual data in the acquisition period; where the actual data is the number of photons collected by the SPAD in each acquisition period in the acquisition period when there is a target object ;

The third acquisition module 12 is configured to acquire the 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;

The determining module 13 is configured to determine the distance between the time-of-flight module and the target object according to the calibrated data.

Since the embodiment of the device part corresponds to the embodiment of the method part, please refer to the description of the embodiment of the method part for the embodiment of the device part, and details will not be repeated here.

In the laser ranging device provided in this embodiment, since the VCSEL emits a laser pulse, the first calibration data within the acquisition time period is acquired by the first acquisition module; wherein, the first calibration data is when there is no target object , the number of photons collected by the SPAD in each acquisition period within the acquisition period; the acquisition period is less than the acquisition period; since the VCSEL emits laser pulses, the actual data in the acquisition period is acquired by the second acquisition module; wherein, the actual data is the existing target In the case of an object, the quantity of photons collected by the SPAD in each acquisition period within the acquisition duration; the first difference between the actual data in each acquisition period and the corresponding first calibration data is obtained by the third acquisition module, and the first The difference is used as calibrated data; the distance between the time-of-flight module and the target object is determined by the determining module according to the calibrated data. In this 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 the target object is detected, and the number of detected photons is higher than the target object due to near-end crosstalk as much as possible. The number of returned photons will lead to the occurrence of misjudgment during distance calculation, improving the accuracy of laser ranging.

FIG. 7 is a structural diagram of a laser ranging device provided in another embodiment of the present application. This embodiment is based on the hardware perspective, as shown in Figure 7, the device for laser ranging includes:

memory 20 for storing computer programs;

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

The laser ranging device provided in this embodiment may include, but not limited to, a smart phone, a tablet computer, a notebook computer or a desktop computer, and the like.

Wherein, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, and the like. Processor 21 can adopt at least one hardware form in Digital Signal Processor (Digital Signal Processor, DSP), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA), Programmable Logic Array (Programmable LogicArray, PLA) accomplish. The processor 21 may also include a main processor and a coprocessor, the main processor is a processor for processing data in the wake-up state, and is also called a central processing unit (Central Processing Unit, CPU); Low-power processor for processing data in standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (Graphics Processing Unit, GPU), and the GPU is used 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, and the AI processor is used to process calculation operations related to machine learning.

Memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include high-speed random access memory, and non-volatile memory, such as one or more magnetic 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 foregoing embodiments can be realized. 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. Wherein, the operating system 202 may include Windows, Unix, Linux and so on. The data 203 may include, but is not limited to, the data involved in the aforementioned laser ranging method, and the like.

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

Those skilled in the art can understand that the structure shown in FIG. 7 does not constitute a limitation on the laser distance measuring device, and may include more or less components than those shown in the illustration.

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, the following method can be implemented: the laser ranging method has the same effect as above.

Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. A computer program is stored on a computer-readable storage medium, and when the computer program is executed by a processor, the steps described in the foregoing method embodiments are implemented.

It can be understood that if the methods in the above embodiments are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or part of the contribution 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 , executing all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other various media that can store program codes. .

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

A laser distance measuring method, device and medium provided in the present application have been introduced in detail above. Each embodiment in the description is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related part, please refer to the description of the method part. It should be pointed out that those skilled in the art can make some improvements and modifications to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

It should also be noted that in this specification, relative terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations There is no such actual relationship or order between the operations. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Claims (10)

1. A method for laser ranging, comprising: Since the laser transmitter emits laser pulses, the first calibration data within the acquisition period is obtained; wherein, the first calibration data is each acquisition of the single photon avalanche diode within the acquisition period in the absence of a target object The number of photons collected periodically; the collection period is shorter than the collection duration; Since the laser transmitter emits laser pulses, the actual data within the acquisition time period is acquired; wherein the actual data is the single photon avalanche diode in the acquisition time period under the condition that the target object exists The number of photons collected in each of the collection periods; Acquiring a first difference between the actual data and the corresponding first calibration data in each of the collection periods, and using the first difference as calibrated data; The distance between the time-of-flight module and the target object is determined according to the calibrated data. 2. The method for laser ranging according to claim 1, wherein said acquisition of the first calibration data within the acquisition duration comprises: Acquiring the first calibration data within a preset time period since the laser emitter emits a laser pulse; wherein the preset time period is shorter than the collection time period, and the collection period is shorter than the preset time period. 3. The method for laser ranging according to claim 2, wherein the actual data comprises the first actual data in the preset duration and the second actual data in the remaining duration, and the remaining duration is The duration of the acquisition duration except the preset duration; the determination of the distance between the time-of-flight module and the target object according to the calibrated data includes: Acquiring a second difference between the first actual data and the corresponding first calibration data in each of the collection periods, and using the second difference as the first calibrated value within the preset time length data; Selecting the first moment corresponding to the maximum number of photons from the first calibrated data and the second actual data; Obtain the first product result of the speed of light and the first moment; Half of the first product result is used as the distance between the time-of-flight module and the target object. 4. The method for laser ranging according to claim 3, wherein the preset duration is determined according to the distance between the single photon avalanche diode and the lens through which the laser pulse passes, and the preset duration is It is assumed that the duration is positively correlated with the distance from the single photon avalanche diode to the lens. 5. The method for laser ranging according to claim 4, characterized in that, after said acquisition of the actual data in the acquisition duration, said method further comprises: determining the second moment corresponding to when the number of photons is the largest according to the actual data; judging whether the second moment is within the remaining duration; If so, acquiring a first ratio between the first actual data and the corresponding first calibration data in each of the collection periods; Obtain the product of each of the first ratios and the corresponding first calibration data, and use each of the products as the second calibration data; Acquiring a third difference between the first actual data and the corresponding second calibration data in each of the collection periods, and using the third difference as the second calibrated value within the preset time length data; Selecting a third moment corresponding to the maximum number of photons from the second calibrated data and the second actual data; If the second moment and the third moment are the same moment, obtain a second product result of the speed of light and the second moment or the third moment; Half of the second product result is used as the distance between the time-of-flight module and the target object. 6. The method for laser ranging according to claim 5, characterized in that, after determining that the second moment is within the remaining duration, the acquisition of the first actual data in each of the collection periods is performed. Before the first ratio of the data to the corresponding first calibration data, the method further includes: obtaining a first maximum number of photons from said first actual data and a second maximum number of photons from said 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, enter the step of acquiring the first ratio between the first actual data and the corresponding first calibration data in each of the collection periods. 7. The method for laser ranging according to any one of claims 1 to 6, wherein the method further comprises: When the laser pulse emitted by the laser emitter collides with the target object, output prompt information representing the colliding with the target object and/or record the corresponding moment of colliding with the target object. 8. A device for laser ranging, characterized in that it comprises: The first acquisition module is used to acquire the first calibration data within the acquisition time period since the laser transmitter emits the laser pulse; wherein, the first calibration data is the single photon avalanche diode in the absence of the target object. The number of photons collected in each collection period within the collection period; the collection period is less than the collection period; The second acquisition module is configured to acquire the actual data within the acquisition duration since the laser transmitter emits the laser pulse; wherein the actual data is the single photon avalanche in the presence of the target object the number of photons collected by the diode in each of the collection periods within the collection period; A third acquiring module, configured to acquire a first difference between the actual data and the corresponding first calibration data in each of the acquisition periods, and use the first difference as calibrated data; A determining module, configured to determine the distance between the time-of-flight module and the target object according to the calibrated data. 9. A laser ranging device, characterized in that it comprises: memory for storing computer programs; A processor, configured to implement the steps of the laser ranging method according to any one of claims 1 to 7 when executing the computer program. 10. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the laser according to any one of claims 1 to 7 is realized The steps of the ranging method.

Images