Method for detecting using laser radar and laser radar

Abstract

The present invention provides a method for detecting using a laser radar, wherein the laser radar includes a detection unit, the detection unit includes multiple detection units, wherein the multiple detection units may correspond to one or more output areas; the method includes the following steps: selecting an output area from the detection unit according to current ambient light information; the output area includes one or more detection units; obtaining echo information of the selected output area; and performing detection according to the echo information of the selected output area. Through the embodiments of the present invention, the signal-to-noise ratio of the laser radar receiving end is improved, and the performance of the laser radar is improved.

Description

Technical Field

[0001] The present disclosure generally relates to the field of optoelectronic technology, and more particularly to a method for detecting using a laser radar and a laser radar using the method. Background Art

[0002] As a device that uses optical methods to accurately measure distance, lidar has been widely used in various fields in recent years, including industry, agriculture, precision measurement and detection, communications and information processing, medical care, military, obstacle monitoring, geological modeling, location acquisition, robots, unmanned vehicles, etc.

[0003] Laser radar ranging is to calculate the distance of obstacles by measuring the flight time of the emitted light returning to the laser radar through the obstacle, and to obtain a series of distance points by scanning to cover different directions and perceive the surrounding environment. The main structure of this type of laser radar generally includes the laser transmitting end and the receiving end and their optical system, signal processing module, control module, scanning structure and other mechanical structures. The receiving end is a very important part, which together with the signal processing module determines the laser radar's distance measurement performance, ranging accuracy and other important indicators. In practical applications, the main problem faced by the receiving end is ambient light noise, which requires the ability to distinguish signals in noise and improve the signal-to-noise ratio. The signal-to-noise ratio directly determines the quality of the signal, which will directly affect the laser radar point cloud quality indicators such as the number of pixels and noise points.

[0004] LiDAR can use a single-photon avalanche diode (SPAD) array as the receiving end. When the SPAD array is used as the receiving device, the background light (the background light mainly refers to the random noise generated by the ambient light reflecting on the obstacle and entering the detector) will raise the output noise floor, and a large number of noise pulses will enter the subsequent device (such as the time-to-digital converter TDC) used to analyze the signal and generate the echo, and the processing capacity of the device is limited. In order to prevent the signal pulse from being overwhelmed by a large amount of noise, it is necessary to control the signal-to-noise ratio of the receiving end and maximize the detection distance. In different weather conditions, different target reflectivity will lead to different noise floors. Therefore, different signal-to-noise ratios have a great impact on the ranging performance of LiDAR. Improving the signal-to-noise ratio has also become an important factor in improving the ranging performance of LiDAR.

[0005] The existing way to improve the signal-to-noise ratio is to optimize the subsequent signal processing through algorithms to improve the signal-to-noise ratio. For example, filters are used to reduce noise, and special coding of filters (such as Barker Code) is used to reduce the noise generated by filtering to achieve signal discrimination. However, this method is not very effective in improving the signal-to-noise ratio in practice.

[0006] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the prior art in the field. Summary of the invention

[0007] The present invention proposes a method for detection using a laser radar, which solves the problem of too low signal-to-noise ratio in the prior art through a solution with a selectable number and range of driving units based on a SPAD array.

[0008] In view of at least one defect of the prior art, the present invention provides a method for detection using a laser radar, wherein the laser radar according to the present invention comprises a detection unit, wherein the detection unit comprises a plurality of detection units, wherein the plurality of detection units may correspond to one or more output areas; the method comprises the following steps:

[0009] a. According to the current ambient light information, an output area is selected from the detection unit; the output area includes one or more detection units;

[0010] b. Obtaining echo information of the selected output area;

[0011] c. Perform detection based on the echo information of the selected output area.

[0012] According to one aspect of the present invention, the method further comprises:

[0013] -determining at least one comparison threshold value according to the ambient light information;

[0014] Wherein, the step a further comprises:

[0015] a′: selecting an output area from the detection unit according to the current ambient light information and the at least one comparison threshold.

[0016] According to one aspect of the present invention, wherein the at least one comparison threshold comprises a first light intensity threshold and a second light intensity threshold, wherein the first comparison threshold is greater than or equal to the second comparison threshold, the one or more output areas at least comprise a first output area and a second output area, and the first output area is smaller than the second output area, the step a' further comprises:

[0017] When the intensity of the current ambient light is greater than the first intensity threshold, selecting the second output region with a smaller area;

[0018] When the intensity of the current ambient light is less than the second intensity threshold, the first output region with a larger area is selected.

[0019] According to one aspect of the present invention, the first comparison threshold is equal to the second comparison threshold.

[0020] According to one aspect of the present invention, the method further comprises the following steps:

[0021] The one or more output areas are determined according to the one or more historical light spot areas.

[0022] According to one aspect of the present invention, the method further comprises:

[0023] Get the light spot area;

[0024] According to the light spot area, determining at least one output area corresponding to the light spot area;

[0025] The step a further comprises:

[0026] a" selecting an output area from the at least one output area according to the current ambient light information, wherein the selected output area is included in the light spot area.

[0027] According to one aspect of the present invention, the method further comprises:

[0028] - Updating the one or more output areas according to the new spot area.

[0029] According to one aspect of the present invention, the detection unit may include a plurality of detectors.

[0030] According to one aspect of the present invention, the detector is a single photon avalanche diode (SPAD).

[0031] According to one aspect of the present invention, the detection unit is a SPADs array or a silicon photoenhanced tube (SiPM).

[0032] According to one aspect of the present invention, the following steps are also included:

[0033] The distance between the laser radar and the target object is obtained according to the output of the detector corresponding to the output area.

[0034] According to another aspect of the present invention, a laser radar is further provided, wherein the laser radar comprises:

[0035] A transmitting unit, wherein the transmitting unit is configured to transmit a detection laser beam for detecting a target object;

[0036] The detection unit is configured to receive the echo reflected by the detection laser beam on the target object and output an echo signal;

[0037] A processing unit is coupled to the detection unit, and is configured to use the detection method to control the detection unit and obtain the echo signal output by the detection unit.

[0038] According to another aspect of the present invention, the processing unit is further configured to:

[0039] The distance between the laser radar and the target object is calculated according to the output signal.

[0040] The embodiments of the present invention detect the selection and judgment of the detection unit and its area in the laser radar, and calculate the distance between the target object and the laser radar according to the echo received by the detection unit, thereby improving the signal-to-noise ratio of the laser radar far-sighting and the performance of the laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 A flow chart of a laser radar detection method according to an embodiment of the present invention is shown;

[0043] Figure 2 A schematic diagram of a SPAD array according to an embodiment of the present invention is shown;

[0044] Figure 3 A block diagram of a laser radar according to an embodiment of the present invention is shown; and

[0045] Figure 4 A flowchart of laser radar ranging according to an embodiment of the present invention is shown;

[0046] Figure 5a A schematic diagram showing the spatial intensity distribution of the echo signal and the ambient light signal in the detection part according to an embodiment of the present invention is shown;

[0047] Figure 5b A schematic diagram showing the spatial intensity distribution of the echo signal and the ambient light signal in the detection unit according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0052] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0053] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0054] Figure 1 FIG. 1 is a flow chart of a laser radar detection method 100 according to an embodiment of the present invention. The laser radar detection method 100 is used to detect a target object at a certain distance from the laser radar. Figure 1 The laser radar detection method 100 is described in detail. As shown in the figure, the detection method 100 includes the following steps:

[0055] In step S101 : the detection unit selects an output area according to the ambient light information.

[0056] The detection unit of the laser radar includes one or more detection units (or pixels), each of which may include multiple detectors. The detection unit receives the laser radar echo and / or ambient light and converts them into electrical signals.

[0057] refer to Figure 2 , Figure 2 The square array shown represents part or all of a detection section, wherein each square represents a detection unit; each square may also contain multiple detectors.

[0058] Preferably, the detector is a device with single-photon detection capability; and the detection unit is implemented by a linear array or a planar array of the detector.

[0059] More preferably, the device with single-photon detection capability is a single-photon avalanche diode (SPAD). The detection unit may be a SPADs array, each SPADs array is composed of independently addressable SPAD devices, and outputs a digital signal after counting the number of received photons; or, a silicon photomultiplier (SiPM) unit, each SiPM unit is formed by a plurality of SPAD devices in parallel, and outputs an analog signal of a pulse peak value corresponding to the number of photons received by the plurality of SPAD devices.

[0060] The detection unit according to the present solution may include a plurality of output areas, and each output area may correspond to one or more detection units.

[0061] Furthermore, those skilled in the art will appreciate that a device having single-photon detection capability may respond to signal light and / or ambient light.

[0062] Among them, the detector can directly obtain the light intensity information of the ambient light, such as obtaining the output of the SPADs array or SiPM unit when the laser of the laser radar does not emit signal light to determine the light intensity information of the ambient light; or, a separate ambient light measurement unit can be set on the laser radar to sense the ambient light intensity. In this case, the ambient light intensity can be measured and obtained at any time without waiting for the moment when the laser radar laser is not emitting light. Those skilled in the art should understand that there are many ways to obtain the light intensity information of the ambient light, which will not be repeated here.

[0063] Specifically, for step S101, the detector selects an output area from the detection unit according to the current ambient light information; the output area includes one or more detection units.

[0064] More specifically, when the ambient light intensity information is less than a predetermined comparison threshold, an output area with a larger area is selected from multiple output areas; when the ambient light intensity information is greater than the predetermined comparison threshold, an output area with a smaller area is selected from multiple output areas.

[0065] Preferably, the laser radar determines at least one comparison threshold value according to the ambient light information; and in step S101, an output area is selected from the detection unit according to the current ambient light information and the at least one comparison threshold value.

[0066] The at least one comparison threshold comprises a first light intensity threshold and a second light intensity threshold.

[0067] In some embodiments, the first comparison threshold is greater than or equal to the second comparison threshold, while in other embodiments, the first light intensity threshold is equal to the second light intensity threshold. That is, only one comparison threshold is used for judgment.

[0068] According to a preferred embodiment of the present solution, the detection unit includes a first output area and a second output area, and the first output area is smaller than the second output area; the step S101 further includes step S1011 (not shown) and step S1012 (not shown). In step S1011, when the ambient light intensity is greater than or equal to a comparison threshold, the first output area is selected; in step S1012, when the ambient light intensity is less than the comparison threshold, the second output area is selected.

[0069] The output area signal-to-noise ratio related to the ambient light may be determined in the following manner.

[0070] When the ambient light intensity is greater than or equal to the comparison threshold, the signal-to-noise ratio of the output area is expressed by the following formula (1):

[0071]

[0072] When the ambient light intensity is less than the comparison threshold, the signal-to-noise ratio of the output area is expressed by the following formula (2):

[0073] SNR = S / C (2);

[0074] Wherein, S is used to indicate the reception ratio of the signal light energy in the output area, N is the number of detectors in the output area, and C is a constant.

[0075] The signal light energy receiving ratio S may be positively correlated with the area ratio of the output region to the entire light spot.

[0076] In general, shot noise based on Poisson distribution can be expressed as Wherein, N is used to indicate all particles obtained by shot noise); in the process of using single-photon detectors for signal light detection, the obtained signal light part is indicated by the energy reception ratio (for example, according to the percentage of the reading area relative to the size of the entire light spot, assumed to be S). Due to the device characteristics of single-photon detectors (such as SPADs or SiPMs) that are easy to saturate, under strong ambient light, the photons of ambient light will affect most detectors. It can be considered that the environmental noise particles obtained correspond to their number, that is, N can be used to indicate the number of detectors included in one or more detection units, thereby obtaining the signal-to-noise ratio formula shown in the above (1). Under weak ambient light conditions, the photons of ambient light have little effect on the detector during the detection process, and the dark count can also be ignored. At this time, the above formula (2) can be used to calculate the signal-to-noise ratio.

[0077] Combination Figure 5a and Figure 5b .in, Figure 5a A schematic diagram showing the intensity distribution of a signal received by a detection unit in a spatial dimension in the case of an echo signal and a relatively strong ambient light signal according to an embodiment of the present invention is shown; Figure 5b The figure shows a schematic diagram of the intensity distribution of the signal received by the detection unit in the spatial dimension when the ambient light signal is weak.

[0078] In the case of strong ambient light, selecting the first output area with a smaller area can reduce the impact of ambient light in the surrounding areas with weaker signal light while covering better signal light; while in the case of weaker ambient light, selecting the second output area with a larger area can obtain as much signal light as possible and improve the signal-to-noise ratio.

[0079] Figure 2 A schematic diagram of a SPAD array according to an embodiment of the present invention is shown, which is used to illustrate the specific method of selecting an output area in step S101 according to a preferred embodiment of the present invention. As shown in the figure, the detection unit is implemented by a SPAD array 200, and the detection unit includes a first output area A1, a second output area A2 and a spot area A3. The area of ​​the first output area A1 is relatively small, for example, it contains 70% of the received laser energy and occupies 9 SPAD detectors; the area of ​​the second output area A2 is relatively large, containing 90% of the received laser energy and occupying 25 SPAD detectors. In addition, the light intensity information of the ambient light is directly detected by the detection unit.

[0080] When the ambient light intensity is high, that is, when the ambient light exceeds the preset comparison threshold, the first output area A1 with a small area is selected as the receiving signal output range. The signal light energy receiving ratio S of the first output area A1 is 70%, and the number of detectors N is 9. According to formula (1), the signal-to-noise ratio SNR1=70% / 3 can be obtained.

[0081] When the ambient light intensity is weak, that is, when the ambient light intensity is lower than the comparison threshold, the second output area A2 with a large area is selected as the received signal output range. Among them, the signal light energy receiving ratio S of the second output area A2 is 90%, at this time, the dark count can be ignored, and the ambient light noise is counted as a constant C; thus, the signal-to-noise ratio of the second output area A2 is: SNR2 = 90% / C.

[0082] Those skilled in the art can understand that, when the ambient light intensity is strong, the signal-to-noise ratio of the second output area A2 is SNR2'=90% / 5, which is less than SNR1=70%3. Obviously, in this case, the signal-to-noise ratio obtained by selecting the first output area A1 is better; and when the ambient light intensity is weak, the signal-to-noise ratio of the first output area A1 is SNR1'=70% / C, which is less than SNR2=90% / C. Obviously, in this case, the signal-to-noise ratio obtained by selecting the second output area A2 is better.

[0083] That is, it can be understood based on the above embodiments that by selecting different output areas according to different intensities of ambient light, a better signal-to-noise ratio can be obtained overall.

[0084] It can be understood that when SiPM is used, N in the above formula (1) can be rewritten as n*N1, where n is the number of detection units, that is, the number of SiPMs, and N1 is the number of microcells contained in each SiPM, that is, the number of SPADs contained in each SiPM.

[0085] It should be noted that the numbers and values ​​here are only examples. In fact, a detection unit can usually contain a large number of single-photon detectors. For example, the size of a SiPM is in the millimeter level (for example, it may be around 1 square mm), and the density of its microcells (the microcell includes a SPAD device used in the SiPM and its corresponding quenching resistor) may range from 100 to 1000 per square millimeter (mm), or even higher than 1000, depending on the size of the microcells used. Similarly, in the case of a SPADs array, the size of each detection unit depends on the number of SPAD detectors it contains, and the number can also range from hundreds to thousands.

[0086] Generally speaking, the echo spot of lidar is several millimeters or even 1 centimeter, that is, usually one spot will cover a dozen or even dozens of detection units.

[0087] Those skilled in the art should understand that the above description is only used to clarify the relative size relationship between the light spot and each detector and detection unit for easy reading. With the development of technology, the size of the detection unit and the echo spot size of the laser radar may change accordingly, and such changes should also be included in the protection scope of the present invention.

[0088] According to yet another preferred embodiment of the present invention, the present invention may not be limited to two output areas.

[0089] For example, a first comparison threshold and a second comparison threshold are set, wherein the first comparison threshold is greater than the second comparison threshold; and a first output area, a second output area and a third output area are set; wherein the area of ​​each area is: first output area < second output area < third output area.

[0090] In addition, the signal-to-noise ratio formula corresponding to each output area is set as follows:

[0091] First output area:

[0092] Second output region: SNR = S / C1 (2');

[0093] Third output region: SNR = S / C2 (3');

[0094] The signal light receiving ratio of each output region is proportional to the area of ​​the output region, that is, the signal light receiving ratios of the first output region, the second output region, and the third output region increase in sequence, and C1 is greater than C2.

[0095] That is, when the ambient light noise is low, determine whether it is less than the second comparison threshold. When the ambient light noise is less than the second comparison threshold, select the third output area to receive the echo, and obtain the echo information of the third output area. At this time, SNR=S / C2 is used to determine its signal-to-noise ratio. Since the third output area receives a higher proportion of signal light, its signal-to-noise ratio is higher. When the ambient light noise is greater than the second comparison threshold and less than the first comparison threshold, select the third output area to receive the echo, and obtain the echo information of the second output area. At this time, SNR=S / C1 is used to determine its signal-to-noise ratio.

[0096] By adopting this differentiation method, a higher overall signal-to-noise ratio can be obtained when the ambient light noise is low.

[0097] Those skilled in the art will appreciate that the size and number of the output areas within the detection unit can be selected by setting different comparison thresholds according to the intensity of the ambient light, and the number of the output areas is not limited to specific numbers such as two or three, and can be set as needed, all of which fall within the scope of protection of the present invention.

[0098] Next, in step S102, the detection unit obtains the echo information of the selected output area.

[0099] Specifically, when all detectors of the detection unit are turned on, step S102 further includes the following steps: reading the detection signal of at least one detector in the selected output area; or, when all detectors of the detection unit are in the off state, step S102 includes: turning on at least one detector in the selected output area; reading the detection signal corresponding to at least one detector in the output area.

[0100] The detection signal is different based on the specific device used. For example, when a SPADs array is used to implement the detection unit, the detection signal output by the output area is a digital signal, which is used to indicate the number of photons in the echo that can be received by multiple detectors, and then determine the echo intensity; for another example, when a SiPM unit is used to implement the detection unit, the detection signal read from the output area is an analog signal, and the waveform peak of the analog signal is used to indicate the intensity of the echo received by multiple detection units.

[0101] Next, in step S103, detection is performed based on the echo information of the selected output area.

[0102] The processing unit of the laser radar can receive the echo information in the selected output area and perform detection. For example, it can calculate the flight time TOF based on the reception time of the echo, thereby calculating the distance of the target object; it can also calculate the reflectivity of the target object based on the pulse width of the echo.

[0103] As described above, the detection unit may preferably include an array of single photon avalanche diodes (SPADs). In the array, each single photon avalanche diode (SPAD) can be addressed individually, so after the output area is selected in step S101, the echo information in the output area can be obtained by addressing and reading the detectors included in the output area, that is, obtaining the electrical signal output by the detectors in the output area.

[0104] According to a preferred embodiment of the present invention, the multiple output areas in the detector may be determined according to at least any one of the following methods.

[0105] 1) Pre-set multiple output areas: For example, multiple detection units of the detection unit are divided into multiple output areas of different sizes in advance.

[0106] 2) generating the at least one output area in real time according to the position information of the light spot area received by the detector;

[0107] Specifically, a light spot area is acquired; and the first output area and the second output area are determined according to the light spot area; wherein the first output area and the second output area are both included in the light spot area.

[0108] For example, when a light spot is received, the center position of the light spot is detected, and based on the center position and the size of the light spot, the first output area is determined to be a concentric circle occupying 70% of the area of ​​the light spot; the second output area is a concentric circle occupying 95% of the area of ​​the light spot, etc.

[0109] 3) reading at least one output area of ​​the history storage;

[0110] Specifically, one or more output regions used last time or in previous times are used as one or more output regions for this measurement.

[0111] Preferably, during this measurement, it is first determined whether at least one output area used in the previous time or the previous times is still within the light spot (for example, when all detectors located at the edge of the output area have signals, it can be considered that they are all within the light spot area). If it is still within the light spot, continue to use the currently stored output area to obtain information; if part of it is not within the light spot, update at least one output area according to the current light spot position and store it.

[0112] For example, the laser radar stores two output areas used last time (called the first output area and the second output area); during a detection process, when a light spot is received, it is determined that the first output area and the second output area are still within the light spot area, and the historically stored first output area and the second output area are used for calculation in this detection; then, during another detection process, it is determined that at least parts of the first output area and the second output area are not within the current light spot area, and based on the area information corresponding to the current light spot, the first output area and the second output area are re-determined; and the first and second output areas are stored for subsequent measurements.

[0113] More preferably, according to a preferred solution of the present invention, the corresponding output area can be determined according to the received center position of the light spot in combination with the historical storage information.

[0114] For example, the memory of the laser radar stores multiple coordinate intervals and multiple output areas corresponding to the multiple coordinate intervals; when the detection unit receives the light spot, it obtains the coordinate information of the center position of the light spot, and reads the output signals of one or more output areas corresponding to the coordinate range based on the coordinate interval corresponding to the center position.

[0115] The present invention also relates to a laser radar, such as Figure 3A block diagram of a laser radar 300 according to an embodiment of the present invention is shown, wherein the laser radar 300 includes a transmitting unit 310, a detecting unit 320 and a processing unit 330, wherein the transmitting unit 310 is configured to transmit a detecting laser beam L1 for detecting a target object OB, the detecting unit 320 includes a detector array 200 (such as the SPAD array described above), and is configured to receive an echo L1' reflected by the detecting laser beam on the target object OB and output an echo signal, and the processing unit 330 is coupled to the detecting unit 320, and the processing unit 330 is configured to use the detection method described above to control the detecting unit 320 and obtain the echo signal outputted by it.

[0116] According to one embodiment of the present invention, the processing unit is further used to calculate the distance between the laser radar and the target object and / or the reflectivity of the target object based on the output signal.

[0117] Figure 4 A flow chart of a laser radar ranging method according to an embodiment of the present invention is shown. The laser radar ranging method 400 is used to detect a target object at a certain distance from the laser radar in the environment around the laser radar, and selects one of two output areas to receive an echo to detect the target object. As shown in the figure, the ranging method 400 includes the following steps:

[0118] In step S401: obtaining ambient light intensity information. As described above, the ambient light intensity information may be obtained through a detection unit or through a separate ambient light measurement unit.

[0119] In step S402: the processing unit sets at least one comparison threshold according to the ambient light intensity. In this distance measurement process, a comparison threshold is set to select the first output area and the second output area in the detection unit.

[0120] In step S403: determine whether the intensity of the ambient light is greater than or equal to the comparison threshold. If the intensity of the ambient light is greater than the comparison threshold, proceed to step S404, otherwise proceed to step S405.

[0121] In step S404: the first output area 1 is selected, and the signal-to-noise ratio is determined according to formula (1). When the ambient light intensity is relatively large, the first output area 1 with a relatively small area is selected for echo detection. The signal-to-noise ratio of the first output area 1 is expressed by the following formula (1):

[0122]

[0123] Wherein, S is used to indicate the reception ratio of the signal light energy in the output area, and N is the number of detectors in the output area.

[0124] In step S405: select the second output area 2, and determine the signal-to-noise ratio according to formula (2). When the ambient light intensity is less than the comparison threshold, select the second output area 2 with a relatively large area for detection, and the signal-to-noise ratio of the second output area 2 is expressed by the following formula (2):

[0125] SNR=S / C (2).

[0126] In step S406: the distance between the laser radar and the target object is obtained according to the output of the detector corresponding to the output area. For example, the TOF (Time of Flight) time is calculated according to the time of flight ranging method to obtain the distance between the target object and the laser radar.

[0127] The present invention selects an output area to receive echoes according to ambient light in the detection unit of the laser radar receiving end, and performs ranging of the laser radar based on the above method. Through the embodiments of the present invention, the signal-to-noise ratio of the overall ranging of the laser radar is improved, the influence of ambient light on the ranging performance of the laser radar can be reduced, and power consumption is saved.

[0128] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0129] Although the embodiments of this specification are disclosed as above, the embodiments of this specification are not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of this specification. Therefore, the protection scope of the embodiments of this specification shall be subject to the scope defined by the claims.

Claims

1. A method for detection using a laser radar, wherein the laser radar comprises a detection unit, the detection unit comprises a plurality of detection units, wherein: The plurality of detection units correspond to a plurality of output regions; different output regions include different numbers of detection units; the method comprises the following steps: a. According to the current ambient light information, selecting an output area from the detection unit; the output area includes one or more detection units; b. Obtaining echo information of the selected output area; c. Detection is performed according to the echo information of the selected output area; The method further comprises: determining at least one comparison threshold value according to the ambient light information; the step a further comprises: a' selecting an output area from the detection unit according to the current ambient light information and the at least one comparison threshold value.

2. The method according to claim 1, wherein: The at least one comparison threshold comprises a first light intensity threshold and a second light intensity threshold, wherein the first light intensity threshold is greater than or equal to the second light intensity threshold, the multiple output areas at least comprise a first output area and a second output area, the first output area is smaller than the second output area, and the step a' further comprises: When the intensity of the current ambient light is greater than the first intensity threshold, selecting the second output region with a smaller area; When the intensity of the current ambient light is less than the second intensity threshold, the first output region with a larger area is selected.

3. The method according to claim 2, wherein: The first light intensity threshold is equal to the second light intensity threshold.

4. The method according to any one of claims 1 to 3, wherein: The method further comprises the following steps: The plurality of output areas are determined according to one or more historical light spot areas.

5. The method according to claim 4, wherein: The method further comprises: The plurality of output areas are updated according to the new light spot area.

6. The method according to any one of claims 1 to 3, wherein: The detection unit includes a plurality of detectors.

7. The method according to claim 6, wherein: The detector is a single photon avalanche diode (SPAD).

8. The method according to claim 7, wherein: The detection unit is a SPADs array or a silicon photoelectric enhancement tube (SiPM).

9. The method according to any one of claims 1 to 3, further comprising the following steps: The distance between the laser radar and the target object is obtained according to the output signal of the detector corresponding to the output area.

10. A laser radar, wherein: The laser radar comprises: A transmitting unit, wherein the transmitting unit is configured to transmit a detection laser beam for detecting a target object; a detection unit configured to receive an echo reflected by the detection laser beam on a target object and output an echo signal; A processing unit, the processing unit is coupled to the detection part, and the processing unit is configured to execute the method according to any one of claims 1 to 9 to control the detection part and obtain the echo signal outputted by the detection part.

11. The laser radar according to claim 10, wherein: The processing unit is further configured to: The distance between the laser radar and the target object is calculated according to the output signal.

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