WO2022037106A1 - 利用激光雷达探测的方法以及激光雷达 - Google Patents

利用激光雷达探测的方法以及激光雷达 Download PDF

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Publication number
WO2022037106A1
WO2022037106A1 PCT/CN2021/089478 CN2021089478W WO2022037106A1 WO 2022037106 A1 WO2022037106 A1 WO 2022037106A1 CN 2021089478 W CN2021089478 W CN 2021089478W WO 2022037106 A1 WO2022037106 A1 WO 2022037106A1
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output
output area
area
detection
lidar
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PCT/CN2021/089478
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English (en)
French (fr)
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孙恺
向少卿
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上海禾赛科技股份有限公司
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Priority to EP21857207.1A priority Critical patent/EP4202483A1/en
Publication of WO2022037106A1 publication Critical patent/WO2022037106A1/zh
Priority to US18/085,053 priority patent/US20230122320A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/4808—Evaluating distance, position or velocity data
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4816—Constructional features, e.g. arrangements of optical elements of receivers alone
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4861—Circuits for detection, sampling, integration or read-out
    • G01S7/4863—Detector arrays, e.g. charge-transfer gates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/487—Extracting wanted echo signals, e.g. pulse detection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497—Means for monitoring or calibrating

Definitions

  • the present disclosure generally relates to the field of optoelectronic technology, and more particularly, to a detection method using a lidar and a lidar using the method.
  • lidar As a device for precise ranging using optical methods, lidar has been widely used in industry, agriculture, precision measurement and detection, communication and information processing, medical treatment, military, obstacle monitoring, geological modeling, location acquisition and robotics in recent years. People and vehicles, etc.
  • Lidar ranging is to calculate the distance of the obstacle by measuring the flight time of the emitted light returning to the lidar through the obstacle, and to cover different directions by scanning means to obtain a series of distance points and perceive the surrounding environment.
  • the main structure of this type of lidar generally includes laser transmitter and receiver and its optical system, signal processing module, control module, scanning structure and other mechanical structures.
  • the receiving end is a very important part, and together with the signal processing module, it determines important indicators such as the ranging performance and ranging accuracy of the lidar.
  • the main problem faced by the receiving end is ambient light noise, which requires the ability to discriminate the signal in the noise and improve the signal-to-noise ratio.
  • the signal-to-noise ratio directly determines the quality of the signal and will directly affect the point cloud quality indicators such as the number of pixels and the number of noise points in the lidar point cloud.
  • Lidar can use the single-photon avalanche diode SPAD array as the receiving end.
  • the background light (the background light mainly refers to the random noise generated by the ambient light entering the detector after being reflected on the obstacle) will By raising the noise floor of the output, a large number of noise pulses enter the device (such as a time-to-digital converter TDC) that is subsequently used to analyze the signal and generate an echo, and the processing capacity of the device is limited.
  • TDC time-to-digital converter
  • different target reflectivity will lead to different noise floor level. Therefore, different signal-to-noise ratios have a great impact on lidar ranging performance. Improving the signal-to-noise ratio has also become an important factor to improve the ranging performance of lidar.
  • the existing way to improve the signal-to-noise ratio is to optimize the subsequent signal processing through an algorithm to improve the signal-to-noise ratio.
  • a filter is used to reduce noise
  • a special code of the filter such as Barker Code
  • this method does not improve the signal-to-noise ratio well in practice.
  • the present invention proposes a detection method using laser radar, which solves the problem of excessively low signal-to-noise ratio in the prior art through a scheme that the number and range of drive units based on the SPAD array are selectable.
  • the present invention proposes a detection method using a lidar.
  • the lidar according to the present invention includes a detection unit, and the detection unit includes a plurality of detection units, wherein the plurality of detection units are Each detection unit may correspond to one or more output areas; the method includes the following steps:
  • the output area includes one or more detection units
  • the method further comprises:
  • step a further comprises:
  • an output area is selected from the detection unit.
  • the at least one comparison threshold includes 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, and the one or more Each output area includes at least 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 includes:
  • the first output area with a larger area is selected.
  • the first comparison threshold is equal to the second comparison threshold.
  • the method further comprises the following steps:
  • the one or more output regions are determined based on the one or more historical spot regions.
  • the method further comprises:
  • the light spot area determine at least one output area corresponding to the light spot area
  • Described step a further comprises:
  • a" According to the current ambient light information, select an output area from the at least one output area, and the selected output area is included in the light spot area.
  • the method further comprises:
  • the detection unit may include a plurality of detectors.
  • the detector is a single photon avalanche diode (SPAD).
  • SPAD single photon avalanche diode
  • the detection unit is an array of SPADs or a silicon photo-enhancer tube (SiPM).
  • the distance between the lidar and the target is obtained.
  • a laser radar is also provided, wherein the laser radar includes:
  • a transmitting unit configured to transmit a detection laser beam for detecting a target
  • the detection part is configured to receive the echo reflected by the detection laser beam on the target and output the echo signal;
  • processing unit is coupled to the detection unit, and the processing unit is configured to use the detection method to control the detection unit and obtain echo signals output by the detection unit.
  • processing unit is further configured to:
  • the distance between the lidar and the target is calculated.
  • the embodiment of the present invention detects the selection and judgment of the detection unit and its area in the laser radar, and calculates 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 and the distance measurement of the laser radar. Lidar performance.
  • FIG. 1 shows a flowchart of a lidar detection method according to an embodiment of the present invention
  • FIG. 2 shows a schematic diagram of a SPAD area array according to an embodiment of the present invention
  • FIG. 3 shows a block diagram of a lidar according to one embodiment of the present invention.
  • FIG. 4 shows a flowchart of lidar ranging according to an embodiment of the present invention
  • Fig. 5a shows a schematic diagram of 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
  • Fig. 5b shows a schematic diagram of 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.
  • connection should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or 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 communication of two elements or the interaction of two elements relation.
  • connection should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or 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 communication of two elements or the interaction of two elements relation.
  • a first feature "on” or “under” a second feature may include direct contact between the first and second features, or may include the first and second features Not directly but through additional features between them.
  • the first feature being “above”, “over” and “above” the second feature includes that the first feature is directly above and diagonally above the second feature, or simply means that the first feature is level higher than the second feature.
  • the first feature “below”, “below” and “beneath” the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature has a lower level than the second feature.
  • FIG. 1 shows a flowchart of a lidar detection method 100 according to an embodiment of the present invention.
  • the lidar detection method 100 is used to detect a target that has a certain distance from the lidar.
  • the lidar detection method 100 will be described in detail below with reference to FIG. 1 .
  • the detection method 100 includes the following steps:
  • step S101 the detection unit selects an output area according to the ambient light information.
  • the detection part of the lidar includes one or more detection units (or may be referred to as pixels, pixels), and each detection unit may include a plurality of detectors.
  • the detection unit receives echoes and/or ambient light of the lidar, and converts them into electrical signals.
  • the grid array shown in FIG. 2 represents a part or all of a detection part, wherein each grid represents a detection unit; each grid may also contain a plurality of detectors.
  • the detector is a device with single-photon detection capability; the detection unit is realized by a linear array or an area array of the detector.
  • the device with single photon detection capability is a single photon avalanche diode (SPAD, Single Photon Avalanche Diode).
  • the detection unit can be an array of SPADs, each SPADs array is composed of SPAD devices that can be independently addressed, and after counting the number of received photons, a digital signal is output; or, a silicon photomultiplier tube (SiPM, Silicon photomultiplier) unit, each SiPM unit is formed by a plurality of SPAD devices in parallel, and outputs an analog signal with a pulse peak corresponding to the number of photons received by the plurality of SPAD devices.
  • SiPM Silicon photomultiplier
  • the detection unit according to the present solution may include multiple output areas, and each output area may correspond to one or more detection units.
  • a device with single-photon detection capability can respond to signal light and/or ambient light.
  • the detector can directly obtain the light intensity information of the ambient light, for example, obtain the output of the SPADs array or the SiPM unit when the laser of the lidar does not emit signal light, to determine the light intensity information of the ambient light, etc.; or, the lidar A separate ambient light measurement unit can be set on the device to sense 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 lidar laser is not emitting light. Those skilled in the art should understand that there are various ways to obtain the light intensity information of the ambient light, which will not be repeated here.
  • 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.
  • the output area with a larger area is selected from the multiple output areas; when the light intensity information of the ambient light is greater than the predetermined comparison threshold, the output area is selected by Select the output area with a smaller area in the area.
  • the lidar determines at least one comparison threshold according to ambient light information; and, in step S101, according to the current ambient light information and the at least one comparison threshold, an output area is selected from the detection unit .
  • the at least one comparison threshold includes a first light intensity threshold and a second light intensity threshold.
  • the first comparison threshold is greater than or equal to the second comparison threshold; and 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.
  • the detection part includes a first output area and a second output area, and the first output area ⁇ second output area; the step S101 further includes a step S1011 (not shown in the figure) and step S1012 (not shown).
  • step S1011 when the ambient light intensity is greater than or equal to the 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.
  • the signal-to-noise ratio of the output area related to ambient light can be determined in the following manner.
  • the signal-to-noise ratio of the output area is expressed by the following formula (1):
  • S is used to indicate the receiving ratio of the signal light energy in the output area
  • N is the number of detectors in the output area
  • C is a constant.
  • the signal light energy receiving ratio S may be positively correlated with the area ratio of the entire light spot occupied by the output area.
  • the shot noise based on the Poisson distribution can be expressed as Among them, N is used to indicate all particles obtained by shot noise); and in the process of signal light detection using a single-photon detector, the obtained signal light part is indicated by the receiving ratio of energy (for example, according to reading area as a percentage of the size of the entire spot, let’s say S), and due to the device properties of single-photon detectors (such as SPADs or SiPM) that are prone to saturation, the photons of ambient light will affect most of the detectors under strong ambient light.
  • N is used to indicate all particles obtained by shot noise
  • the obtained signal light part is indicated by the receiving ratio of energy (for example, according to reading area as a percentage of the size of the entire spot, let’s say S)
  • the photons of ambient light will affect most of the detectors under strong ambient light.
  • the obtained environmental noise particles correspond to their number, that is, N can be used to indicate the number of detectors contained in one or more detection units, so as to obtain the above-mentioned (1)
  • the signal-to-noise ratio formula shown in 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 be ignored. In this case, the aforementioned formula (2) can be used to calculate the signal-to-noise ratio.
  • FIG. 5a shows a schematic diagram of the intensity distribution of the signal received by the detection unit in the spatial dimension in the case of an echo signal and a strong ambient light signal according to an embodiment of the present invention
  • selecting the first output area with a smaller area can cover better signal light while reducing the influence of ambient light in areas with weak surrounding signal light.
  • selecting a second output area with a larger area can obtain as much signal light as possible and improve the signal-to-noise ratio.
  • FIG. 2 shows a schematic diagram of a SPAD area array according to an embodiment of the present invention, which is used to illustrate a specific manner of selecting an output area in step S101 according to a preferred embodiment of the present invention.
  • the detection part is realized by the SPAD area array 200, and the detection part includes a first output area A1, a second output area A2 and a light spot area A3.
  • the area of the first output area A1 is relatively small, for example, including 70% of the received laser energy, occupying 9 SPAD detectors; the area of the second output area A2 is relatively large, including 90% of the received laser energy, occupying 25% a SPAD detector.
  • the light intensity information of the ambient light is directly detected by the detection unit.
  • the first output area A1 with a small area is selected as the output range of the received signal, and the signal light energy of the first output area A1 is received.
  • the ratio S is 70%
  • N in the aforementioned 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
  • a detection unit can contain a large number of single-photon detectors.
  • the size of a SiPM is in the order of millimeters (for example, it may be about 1 square mm), and the density of its microcells (the one microcell includes a SPAD device used in the SiPM and its corresponding quenching resistance) may be in each square Millimeters (mm) ranging from 100 to 1000, and possibly even higher than 1000, depending on the size of the minicells used.
  • the size of each detection unit depends on the number of SPAD detectors it contains, and the number may vary from several hundred to several thousand.
  • the echo spot of lidar is about a few millimeters or even 1 centimeter, that is, usually one spot will cover a dozen or even dozens of detection units.
  • the present invention may not be limited to two output areas.
  • 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 is: the first output area ⁇ the second output area ⁇ the third output area.
  • the signal light receiving ratio of each output region is proportional to the area of the output region, that is, the signal light receiving ratio of the first output region, the second output region, and the third output region increases sequentially, and C1 is greater than C2.
  • the ambient light noise 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 echoes, and obtain the echoes of the third output area.
  • the size and number of the output areas in the detection unit can be selected by setting different comparison thresholds according to the light intensity of the ambient light, and the number of the output areas is not limited to a specific number, such as two One or three can be set as required, and these all fall within the protection scope of the present invention.
  • step S102 the detection unit acquires the echo information of the selected output area.
  • step S102 further includes the following steps: reading the detection signal of at least one detector in the selected output area; or, when all the detectors of the detection section are in an off state , step S102 includes: turning on at least one detector in the selected output area; reading a detection signal corresponding to at least one detector in the output area.
  • the detection signal is different based on the specific device used.
  • the detection signal output by the output area is a digital signal, which is used to indicate the number of photons in the echoes that can be received by multiple detectors, and then determine the echo intensity;
  • the SiPM unit is used to implement the detection unit
  • the read detection signal of the output area is an analog signal, and the waveform peak value of the analog signal is used to indicate the intensity of the echoes received by the plurality of detection units.
  • step S103 detection is performed according to the echo information of the selected output area.
  • the processing unit of the lidar can receive the echo information in the selected output area and perform detection, for example, according to the receiving time of the echo, calculate the TOF of the time of flight, so as to calculate the distance of the target; or according to the pulse width of the echo, Calculates the reflectivity of the target.
  • the detection unit may preferably comprise an array of single-photon avalanche diodes SPAD.
  • each single-photon avalanche diode SPAD can be individually addressed, so after the output region is selected in step S101, the detectors included in the output region can be addressed and read to obtain the The echo information in the output area, that is, the electrical signal output by the detector in the output area is obtained.
  • the plurality of output regions in the detector can be determined according to at least any one of the following manners.
  • the light spot area is acquired; 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 within the area.
  • the center position of the light spot is detected, and based on the center position and the size of the light spot, it is determined that the first output area is a concentric circle that occupies 70% of the light spot; the second output area is a concentric circle that occupies 95% of the light spot, etc. .
  • one or more output areas used in the previous or previous times are used as one or more output areas for this measurement.
  • this measurement first determine whether at least one output area used in the previous or several 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 in 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.
  • the lidar stores the two output areas (called the first output area and the second output area) that were used before; in a detection process, when a light spot is received, the first output area and the second output area are judged If the area is still in the spot area, the first output area and the second output area stored in the history are used for calculation in this detection; then, in another detection process, it is determined that the first output area and the second output area respectively If at least a part is not in the current spot area, the first output area and the second output area are re-determined based on the area information corresponding to the current spot; and the first and second output areas are stored for subsequent measurement.
  • the first output area and the second output area are judged If the area is still in the spot area, the first output area and the second output area stored in the history are used for calculation in this detection; then, in another detection process, it is determined that the first output area and the second output area respectively If at least a part is not in the current spot area, the first output area and the second output area are re-determined based on
  • the corresponding output area can be determined according to the received center position of the light spot and combined with the historical storage information.
  • the memory of the lidar stores multiple coordinate intervals and multiple output areas corresponding to the multiple coordinate intervals; then when the detection unit receives the light spot, it obtains the coordinate information of the center position of the light spot, and according to the The coordinate range corresponding to the center position, and then read the output signals of one or more output areas corresponding to the coordinate range.
  • the present invention also relates to a lidar.
  • FIG. 3 a block diagram of a lidar 300 according to an embodiment of the present invention is shown.
  • the lidar 300 includes a transmitting unit 310, a detecting unit 320, and a processing unit 330, wherein the transmitting
  • the unit 310 is configured to emit a detection laser beam L1 for detecting the target object OB
  • the detection unit 320 includes a detector array 200 (such as the SPAD area array described above), and is configured to receive the detection laser beam and reflect it on the target object OB
  • the echo L1 ′ is outputted and the echo signal is output.
  • the processing unit 330 is coupled to the detection unit 320, and the processing unit 330 is configured to use the detection method as described above to control the detection unit 320 and obtain the detection unit 320.
  • the output echo signal is coupled to the detection unit 320, and the processing unit 330 is configured to use the detection method as described above to control the detection unit 320 and obtain the detection unit 320.
  • the processing unit is further configured to: calculate the distance between the lidar and the target and/or the reflectivity of the target according to the output signal.
  • FIG. 4 shows a flowchart of a lidar ranging method according to an embodiment of the present invention.
  • the lidar ranging method 400 is used to detect a target that has a certain distance from the lidar in the surrounding environment of the lidar, And select one of the two output areas to receive the echo to detect the target.
  • the ranging method 400 includes the following steps:
  • step S401 obtaining ambient light intensity information.
  • the ambient light intensity information can be acquired through the detection unit, or the ambient light intensity information can be acquired through a separate ambient light measurement unit.
  • step S402 the processing unit sets at least one comparison threshold according to the ambient light intensity.
  • a comparison threshold is set for selecting the first output area and the second output area in the detection unit.
  • step S403 it is determined whether the light intensity of the ambient light is greater than or equal to the comparison threshold. When the light intensity of the ambient light is greater than the comparison threshold, go to step S404, otherwise go to step S405.
  • step S404 select the first output area 1, and determine the signal-to-noise ratio according to formula (1).
  • the first output area 1 with a relatively small area is selected for echo detection.
  • the signal-to-noise ratio of the first output region 1 is expressed by the following formula (1):
  • S is used to indicate the receiving ratio of the signal light energy in the output area
  • N is the number of detectors in the output area.
  • step S405 select the second output area 2, and determine the signal-to-noise ratio according to formula (2).
  • the second output area 2 with a relatively large area is selected for detection, and the signal-to-noise ratio of the second output area 2 is expressed by the following formula (2):
  • step S406 the distance between the lidar and the target is obtained according to the output of the detector corresponding to the output area.
  • the TOF (Time of flight) time is calculated according to the time-of-flight ranging method to obtain the distance between the target and the lidar.
  • the present invention selects the output area according to the ambient light in the detection unit of the laser radar receiving end to receive the echo, and performs ranging for the laser radar based on the above method.
  • 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 can be saved at the same time.

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  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

一种利用激光雷达（300）探测的方法（100），激光雷达（300）包括一探测部，探测部包括多个探测单元（320），其中，多个探测单元（320）可对应一个或多个输出区域；方法（100）包括以下步骤：根据当前的环境光信息，由探测部中选择一输出区域（S101）；输出区域包括一个或多个探测单元（320）；获取所选的输出区域的回波信息（S102）；根据所选的输出区域的回波信息，进行探测（S103）。提高了激光雷达（300）接收端的信噪比，提高了激光雷达（300）的性能。

Description

利用激光雷达探测的方法以及激光雷达 技术领域
本公开大致涉及光电技术领域，尤其涉及一种利用激光雷达探测的方法及使用该方法的激光雷达。
背景技术
激光雷达作为一种使用光学方法精准测距的装置在近年来广泛应用于工业、农业、精密测量和探测、通讯与信息处理、医疗、军事、障碍监测、地质建模、位置获取及机器人、无人车等等各个领域。
激光雷达测距是通过测量发射光经障碍物返回激光雷达的飞行时间计算障碍物距离，通过扫描手段覆盖不同方位从而获取一系列距离点，感知周围环境。此类激光雷达的主要结构一般包括激光发射端与接收端及其光学系统、信号处理模块、控制模块、扫描结构及其他机械结构。接收端是十分重要的部分，其与信号处理模块共同决定了激光雷达的测远性能、测距精度等重要指标。在实际应用中，接收端主要面临的问题是环境光噪音，这就要求在噪音中对信号的甄别能力，提高信噪比。信噪比直接决定了信号的质量将直接影响激光雷达点云的像素数、噪点数等点云质量指标。
激光雷达可以利用单光子雪崩二极管SPAD阵列作为接收端，在这种以SPAD阵列作为接收器件时候，背景光(背景光主要指环境光照在障碍物上反射后进入探测器而产生的随机噪声)会抬高输出的底噪，大量的噪声脉冲进入后续用于分析信号而生成回波的器件(例如时间数字转换器TDC)中，而器件的处理能力有限。为了避免信号脉冲被大量噪声淹没，需要控制接收端的信噪比，尽量扩大探测距离。在不同的天气下，不同的目标反射率，都会导致不同的底噪水平。所以，不同的信噪比，对激光雷达测距性能影响非常大。而提高信噪比也成为提高激光雷达测距性能的一个重要影响因素。
现有的提高信噪比的方式是，通过算法对后续信号处理进行优化从而提高信噪比。例如使用滤波器降低噪声，并通过滤波器的特殊编码(如Barker Code)降低滤波产生的噪声，实现信号甄别。但这种方法在实践中提高信噪比的效果并不好。
背景技术部分的内容仅仅是发明人所知晓的技术，并不当然代表本领域的现有技术。
发明内容
本发明提出一种利用激光雷达探测的方法，通过基于SPAD阵列的驱动单元数和范围可选的方案，解决了现有技术中信噪比过低的问题。
有鉴于现有技术的至少一个缺陷，本发明提出一种利用激光雷达探测的方法，根据本发明的所述激光雷达包括一探测部，所述探测部包括多个探测单元，其中，所述多个探测单元可对应一个或多个输出区域；所述方法包括以下步骤：
a.根据当前的环境光信息，由所述探测部中选择一输出区域；所述输出区域包括一个或多个探测单元；
b.获取该所选的所述输出区域的回波信息；
c.根据该所选的输出区域的回波信息，进行探测。
根据本发明的一个方面，其中，所述方法进一步包括：
-根据环境光信息，来确定至少一个比较阈值；
其中，所述步骤a进一步包括：
a'根据所述当前的环境光信息以及所述至少一个比较阈值，由所述探测部中选择一输出区域。
根据本发明的一个方面，其中，所述至少一个比较阈值包括第一光强阈值和第二光强阈值，其中，所述第一比较阈值大于等于所述第二比较阈值，所述一个或多个输出区域至少包括第一输出区域和第二输出区域，所述第一输出区域小于第二输出区域，所述步骤a'进一步包括：
当所述当前的环境光的光强大于所述第一光强阈值时，选择面积较小的所述第二输出区域；
当所述当前的环境光的光强小于所述第二光强阈值时，选择面积较大的所述第一输出区域。
根据本发明的一个方面，其中，所述第一比较阈值等于所述第二比较阈值。
根据本发明的一个方面，其中，所述方法进一步包括以下步骤：
根据一个或多个历史光斑区域，确定所述一个或多个输出区域。
根据本发明的一个方面，其中，所述方法进一步包括：
获取光斑区域；
根据所述光斑区域，确定与所述光斑区域对应的至少一个输出区域；
所述步骤a进一步包括：
a"根据所述当前的环境光信息，由所述至少一个输出区域中选择一输出区域，所选择的所述输出区域包含于所述光斑区域中。
根据本发明的一个方面，其中，所述方法进一步包括：
-根据新光斑区域来更新所述一个或多个输出区域。
根据本发明的一个方面，其中，所述探测单元可包括多个探测器。
根据本发明的一个方面，其中，所述探测器为单光子雪崩二极管(SPAD)。
根据本发明的一个方面，其中，所述探测单元为SPADs阵列或硅光电增强管(SiPM)。
根据本发明的一个方面，还包括以下步骤：
根据所述输出区域对应的探测器的输出，得到所述激光雷达与目标物之间的距离。
根据本发明的另一个方面，还提供一种激光雷达，其中，所述激光雷达包括：
发射单元，所述发射单元配置成发射探测激光束用于探测目标物；
所述探测部，配置成接收所述探测激光束在目标物上反射的回波并输出回波信号；
处理单元，所述处理单元与所述探测部耦接，所述处理单元并配置成使用所述的探测方法，来控制所述探测部并获得其所输出的回波信号。
根据本发明的另一个方面，其中，所述处理单元还用于：
根据所述输出信号，计算所述激光雷达与目标物之间的距离。
本发明的实施例通过对激光雷达中探测单元及其区域的选择和判断进行探测，并根据探测单元接收的回波计算目标物与激光雷达的距离，提高了激光雷达测远的信噪比和激光雷达的性能。
附图说明
附图用来提供对本发明的进一步理解，并且构成说明书的一部分，与本发明的实施例一起用于解释本发明，并不构成对本发明的限制。在附图中：
图1示出了根据本发明一个实施例的激光雷达探测方法的流程图；
图2示出了根据本发明一个实施例的SPAD面阵的示意图；
图3示出了根据本发明一个实施例的激光雷达的框图；和
图4示出了根据本发明一个实施例的激光雷达测距的流程图；
图5a示出了根据本发明的一个实施例的回波信号与环境光信号的在探测部的空间强度分布示意图；
图5b示出了根据本发明的一个实施例的回波信号与环境光信号的在探测部的空间强度分布示意图。
具体实施方式
在下文中，仅简单地描述了某些示例性实施例。正如本领域技术人员可认识到的那样，在不脱离本发明的精神或范围的情况下，可通过各种不同方式修改所描述的实施例。因此，附图和描述被认为本质上是示例性的而非限制性的。
在本发明的描述中，需要理解的是，术语"中心"、"纵向"、"横向"、"长度"、"宽度"、"厚度"、"上"、"下"、"前"、"后"、"左"、"右"、"竖直"、"水平"、"顶"、"底"、"内"、"外"、"顺时针"、"逆时针"等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。此外，术语"第一"、"第二"仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。 由此，限定有"第一"、"第二"的特征可以明示或者隐含地包括一个或者更多个所述特征。在本发明的描述中，"多个"的含义是两个或两个以上，除非另有明确具体的限定。
在本发明的描述中，需要说明的是，除非另有明确的规定和限定，术语"安装"、"相连"、"连接"应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接:可以是机械连接，也可以是电连接或可以相互通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本发明中，除非另有明确的规定和限定，第一特征在第二特征之"上"或之"下"可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征"之上"、"上方"和"上面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征"之下"、"下方"和"下面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度小于第二特征。
下文的公开提供了许多不同的实施方式或例子用来实现本发明的不同结构。为了简化本发明的公开，下文中对特定例子的部件和设置进行描述。当然，它们仅仅为示例，并且目的不在于限制本发明。此外，本发明可以在不同例子中重复参考数字和/或参考字母，这种重复是为了简化和清楚的目的，其本身不指示所讨论各种实施方式和/或设置之间的关系。此外，本发明提供了的各种特定的工艺和材料的例子，但是本领域普通技术人员可以意识到其他工艺的应用和/或其他材料的使用。
以下结合附图对本发明的优选实施例进行说明，应当理解，此处所描述的优选实施例仅用于说明和解释本发明，并不用于限定本发明。
图1示出了根据本发明一个实施例的激光雷达探测方法100的流程图。所述激光雷达探测方法100用于探测与所述激光雷达有一定距离的目标物，下面将结合图1对所述激光雷达探测方法100作详细说明。如图所示，所述探测方 法100包括以下步骤：
在步骤S101：探测部根据环境光信息，选择一输出区域。
其中，激光雷达的所述探测部包括一个或多个探测单元(或可称之为像素，pixel)，每个探测单元可包括多个探测器。所述探测部接收激光雷达的回波和/或环境光，并转换为电信号。
参考图2，图2所示的方格阵列代表一探测部的部分或全部，其中每个方格代表一探测单元；每个方格内还可包含多个探测器。
优选的，所述探测器为具有单光子探测能力的器件；所述探测单元由该探测器的线阵或者面阵来实现。
更优选地，该具有单光子探测能力的器件为单光子雪崩二极管(SPAD，Single Photon Avalanche Diode)。其中，所述探测单元可以为SPADs阵列，每个SPADs阵列由可被独立寻址的SPAD器件构成，对接收到的光子数目进行计数后，输出数字信号；或者，为硅光电倍增管(SiPM,Silicon photomultiplier)单元，每个SiPM单元由多个SPAD器件并联形成，输出与该多个SPAD器件接收到的光子数量相应的脉冲峰值的模拟信号。
其中，根据本方案的探测部可包含多个输出区域，各个输出区域可对应一个或多个探测单元。
并且，本领域技术人员应可理解，具有单光子探测能力的器件，可以响应信号光和/或环境光。
其中，探测器可直接获取环境光的光强信息，诸如，获取SPADs阵列或SiPM单元在激光雷达的激光器未发射信号光时的输出，来确定环境光的光强信息等；或者，该激光雷达上可以设置单独的环境光测量单元，用于感测环境光强度。这种情况下，可以随时测量和获得环境光强度，而无需等待激光雷达激光器未发光的时刻。本领域技术人员应可理解，可有多种获取环境光的光强信息方式，此处不再赘述。
具体地，对于步骤S101，探测器根据当前的环境光信息，由所述探测部中选择一输出区域；所述输出区域包括一个或多个探测单元。
更具体地，当环境光的光强信息小于预定的比较阈值时，由多个输出区域 中选择面积较大的输出区域；当环境光的光强信息大于预定的比较阈值时，由多个输出区域中选择面积较小的输出区域。
优选地，激光雷达根据环境光信息，来确定至少一个比较阈值；并且，在步骤S101中，根据所述当前的环境光信息以及所述至少一个比较阈值，由所述探测部中选择一输出区域。
其中，该至少一个比较阈值包括第一光强阈值和第二光强阈值。
在一些实施例中，所述第一比较阈值大于等于所述第二比较阈值；而在另一些实施例中，第一光强阈值等于第二光强阈值。亦即，仅采用一个比较阈值进行判断。
根据本方案的一个优选实施例，所述探测部包括第一输出区域和第二输出区域，且所述第一输出区域＜第二输出区域；所述步骤S101进一步包括步骤S1011(图未示)和步骤S1012(图未示)。在步骤S1011中，当环境光强大于等于比较阈值时，选择所述第一输出区域；在步骤S1012中，当环境光强小于所述比较阈值时，选择所述第二输出区域。
其中，与环境光相关的输出区域信噪比可采用以下方式来确定。
当环境光强大于等于比较阈值时，输出区域的信噪比采用下式(1)表示：
Figure PCTCN2021089478-appb-000001
当环境光强小于比较阈值时，输出区域的信噪比采用下式(2)表示：
SNR＝S/C    (2)；
其中，S用于指示该输出区域的信号光能量的接收比例，N为该输出区域的探测器数量，C为一常数。
其中，信号光能量接收比例S可以与输出区域所占整个光斑的面积比例正相关。
通常，基于根据泊松分布的散粒噪音可以表示为
Figure PCTCN2021089478-appb-000002
其中，N用于指示散粒噪音所获得的所有粒子)；而在利用单光子探测器进行信号光探测的过程中，将所获得的信号光部分用能量的接收比例来指示(比如按照读取区域相对于整个光斑的大小的百分比，假设为S)，而由于单光子探测器(如SPADs或SiPM)易于饱和的器件特性，在较强环境光下，环境光的光子会对大部分探测器产生 影响，可以认为，其所获得的环境噪音粒子与其个数相对应，亦即，可以用N来指示一个或多个探测单元中所包含的探测器的个数，从而获得如前述(1)中所示的信噪比公式。而在弱环境光条件下，在探测过程中环境光的光子对于探测器影响较小，而暗计数也可以忽略不计，此时可采用前述公式(2)来计算信噪比。
结合图5a和图5b。其中，图5a示出了根据本发明的一个实施例的回波信号与较强环境光信号的情况下，探测部所接收到的信号在空间维度上的强度分布示意图；图5b示出了在环境光信号较弱的情况下，探测部所接收到的信号在空间维度上的强度分布示意图。
在较强的环境光情况下，选择面积较小的第一输出区域，能够在覆盖较好的信号光的同时，减少周围信号光较弱区域的环境光的影响；而在较弱环境光的情况下，选择面积较大的第二输出区域，能够获得尽可能多的信号光，提升信噪比。
图2示出了根据本发明一个实施例的SPAD面阵的示意图，用于说明根据本发明优选实施例的步骤S101中选择一输出区域的具体方式。如图所示，探测部由SPAD面阵200来实现，该探测部中包括第一输出区域A1，第二输出区域A2和光斑区域A3。其中所述第一输出区域A1的面积较小，例如包含70％接收激光能量，占据9个SPAD探测器；所述第二输出区域A2的面积相对较大，包含90％接收激光能量，占据25个SPAD探测器。并且，由探测部直接探测环境光的光强信息。
在环境光的光强较的情况下，亦即，当环境光超过预设的比较阈值时，选择面积小的第一输出区域A1作为接收信号输出范围，第一输出区域A1的信号光能量接收比例S为70％，探测器数量N为9，根据公式(1)计算可得信噪比为SNR1＝70％/3。
在环境光的光强较弱的情况下，亦即，即环境光低于比较阈值时，选择面积大的第二输出区域A2作为接收信号输出范围。其中，第二输出区域A2的信号光能量接收比例S为90％，此时可忽略暗计数，并将环境光噪音计做一常数C；从而得到第二输出区域A2的信噪比为：SNR2＝90％/C。
本领域技术人员可以理解，在环境光的光强较强的情况下，第二输出区域A2的信噪比为SNR2'＝90％/5，小于SNR1＝70％3，显然，在该情况下，选择第一输出区域A1所能获得的信噪比较好；而在环境光的光强较弱的情况下，第一输出区域A1的信噪比为SNR1'＝70％/C,小于SNR2＝90％/C，显然，在该情况下，选择第二输出区域A2所能获得的信噪比较好。
亦即，基于上述实施例可以理解，通过根据不同的环境光的强度，选择不同的输出区域，能够在整体上获得更好的信噪比。
可以理解，当采用SiPM时，前述公式(1)中的N可改写为n*N1，其中，n为探测单元数量，亦即SiPM的个数，而N1为每个SiPM中包含的微细胞数量，亦即，每个SiPM中所包含的SPAD的数量
需要说明的是，此处的数量和数值仅为举例，事实上，通常一个探测单元能包含的单光子探测器数量较多。如一个SiPM的尺寸在毫米级(例如可能在1平方mm左右)，而其微细胞(所述一个微细胞包括SiPM中所采用的一个SPAD器件及其对应的淬灭电阻)密度可能在每平方毫米(mm)100个至1000个不等，甚至还可能高于1000个，取决于其采用的微细胞的大小。相似地，而SPADs阵列的情况下，每个探测单元的大小取决于其所包含的SPAD探测器的个数，其个数也可以从几百到上千不等。
而通常来说，激光雷达的回波光斑在几毫米甚至1厘米左右，亦即，通常一个光斑会覆盖十几甚至几十个探测单元。
本领域技术人员应可理解，上述说明仅用于明确光斑与各个探测器、探测单元之间的相对尺寸关系，便于阅读。随着技术的发展，探测单元的尺寸以及激光雷达的回波光斑尺寸可能发生相应的改变，此类变化后的情况也应包含于本发明的保护范围内。
根据本发明的又一个优选实施例，本发明可不限于两个输出区域。
例如，设定第一比较阈值和第二比较阈值，其中，第一比较阈值大于第二比较阈值；并且，设置第一输出区域、第二输出区域和第三输出区域；其中，各个区域的面积为：第一输出区域＜第二输出区域＜第三输出区域。
并且，设定各个输出区域对应的信噪比公式如下：
第一输出区域：
Figure PCTCN2021089478-appb-000003
第二输出区域：SNR＝S/C1    (2')；
第三输出区域：SNR＝S/C2    (3')；
其中，各个输出区域的信号光接收比例与输出区域的面积成正比，亦即，第一输出区域、第二输出区域、第三输出区域的信号光接收比例依次增大，且C1大于C2。
亦即，当环境光噪音较低时，判断其是否小于第二比较阈值，当环境光噪音小于第二比较阈值时，选择第三输出区域接收回波，并获取所述第三输出区域的回波信息；此时采用SNR＝S/C2确定其信噪比，由于第三输出区域接受信号光的比例较高，因此其信噪比较高；环境光噪音大于第二比较阈值，且小于第一比较阈值时，选择第三输出区域接收回波，并获取所述第二输出区域的回波信息；此时采用SNR＝S/C1确定其信噪比。
通过采用这种区分方式，可以在环境光噪音较低的情况下，获得更高的整体信噪比。
本领域的技术人员可以理解，所述探测单元内的输出区域的大小和数量可以根据环境光的光强大小设置不同的比较阈值进行选择，所述输出区域的数量并不限于具体的数字如两个或三个，可以根据需要进行设置，这些都落入本发明的保护范围内。
接着，在步骤S102中，探测部获取该所选的所述输出区域的回波信息。
具体地，当探测部的所有探测器已开启时，步骤S102进一步包括以下步骤：读取所选输出区域内的至少一个探测器的探测信号；或者，当探测部的所有探测器均在关闭状态时，步骤S102包括：开启所选的输出区域内的至少一个探测器；读取该输出区域中的至少一个探测器所对应的探测信号。
其中，所述探测信号基于具体所采用的器件的不同而不同。例如，当采用SPADs阵列来实现探测单元时，输出区域所输出的探测信号为数字信号，用于指示多个探测器所能接收到的回波中光子数量，进而确定回波强度；又例如，当采用SiPM单元来实现探测单元时，读取到的输出区域的探测信号为模拟信号，该模拟信号的波形峰值用于指示多个探测单元所接收到的回波的强度等。
接着，在步骤S103中，根据该所选的输出区域的回波信息，进行探测。
激光雷达的处理单元可接收所选择的输出区域内的回波信息，进行探测，例如根据回波的接收时间，计算飞行时间TOF，从而计算目标物的距离；也可以根据回波的脉冲宽度，计算目标物的反射率。
如上所述，所述探测单元优选地可以包括单光子雪崩二极管SPAD构成的阵列。在该阵列中，每个单光子雪崩二极管SPAD可以单独寻址，因此可以在步骤S101中选定了输出区域之后，通过对该输出区域内所包括的探测器进行寻址并读取，获得该输出区域内的回波信息，亦即，获得该输出区域内的探测器输出的电信号。
根据本发明的一个优选实施例，可根据以下至少任一种方式，来确定所述探测器中的多个输出区域。
1)预先设定的多个输出区域。例如，预先将探测部的多个探测单元分割为多个大小不同的输出区域。
2)根据探测器所接收到的光斑区域的位置信息，实时生成所述至少一个输出区域；
具体地，获取光斑区域；根据所述光斑区域，来确定所述第一输出区域和所述第二输出区域；其中，所述第一输出区域和所述第二输出区域均包含于所述光斑区域内。
例如，接收到光斑时，检测光斑的中心位置，并基于该中心位置及光斑大小，确定第一输出区域为占光斑70％面积的同心圆；第二输出区域为占光斑95％的同心圆等。
3)读取历史存储的至少一个输出区域；
具体地，根据前次或前几次所采用的一个或多个输出区域作为本次测量的一个或多个输出区域。
优选地，本次测量时，先判断前次或前几次所采用的至少一个输出区域是否仍然在光斑内(如，当位于输出区域边缘探测器均有信号时，可认为其都在光斑区域内)，如仍在光斑内，则继续使用当前存储的输出区域来获得信息；如有部分未在光斑内，则根据当前光斑位置来更新至少一个输出区域并存储。
例如，激光雷达存储了前次使用过的两个输出区域(称为第一输出区域和第二输出区域)；在一次探测过程中，接收到光斑时，判断该第一输出区域和第二输出区域仍在光斑区域内，则该次探测中使用该历史存储的第一输出区域和第二输出区域来进行计算；接着，在又一次探测过程中，判断第一输出区域和第二输出区域分别至少有部分未在当前的光斑区域内，则基于当前光斑对应的区域信息，重新确定第一输出区域和第二输出区域；并存储该第一和第二输出区域，供后续测量使用。
更优选地，根据本发明一个优选方案，可根据接收到的光斑中心位置，并结合历史存储信息，来确定相应的输出区域。
例如，激光雷达的存储器中存储有多个坐标区间，以及与该多个坐标区间分别对应的多个输出区域；则当探测单元接收到光斑时，获取光斑的中心位置的坐标信息，并根据该中心位置对应的坐标区间，进而读取该坐标范围对应的一个或多个输出区域的输出信号。
本发明还涉及一种激光雷达，如图3示出的根据本发明一个实施例的激光雷达300的框图，所述激光雷达300包括发射单元310、探测单元320和处理单元330，其中所述发射单元310配置成发射探测激光束L1用于探测目标物OB，所述探测单元320包括探测器阵列200(如上述的SPAD面阵)，并配置成接收所述探测激光束在目标物OB上反射的回波L1’并输出回波信号，所述处理单元330与所述探测单元320耦接，所述处理单元330配置成使用如上所述的探测方法，来控制所述探测单元320并获得其所输出的回波信号。
根据本发明的一个实施例，其中所述处理单元还用于：根据所述输出信号，计算所述激光雷达与目标物之间的距离和/或目标物的反射率。
图4示出了根据本发明一个实施例的激光雷达测距方法的流程图，所述激光雷达的测距方法400用于探测激光雷达周围环境中与所述激光雷达有一定距离的目标物，且在两个输出区域中选择一个对回波进行接收，以探测目标物。如图所示，所述测距方法400包括以下步骤：
在步骤S401：获取环境光强信息。如上所述，可以通过探测单元获取环境光强信息，也可以通过单独的环境光测量单元获取环境光强信息。
在步骤S402：处理单元根据环境光强设定至少一个比较阈值。在本测距流程里，设定了一个比较阈值，用于对探测单元中的第一输出区域和第二输出区域进行选择。
在步骤S403：判断环境光的光强是否大于或等于比较阈值。当环境光的光强大于比较阈值时，进行到步骤S404，否则进行到步骤S405。
在步骤S404：选择第一输出区域1，根据公式(1)确定信噪比。当环境光的光强比较大时，选择面积相对较小的第一输出区域1进行回波探测。第一输出区域1的信噪比采用下式(1)表示：
Figure PCTCN2021089478-appb-000004
其中，S用于指示该输出区域的信号光能量的接收比例，N为该输出区域的探测器数量。
在步骤S405：选择第二输出区域2，根据公式(2)确定信噪比。当环境光强小于比较阈值时，选择面积相对较大的第二输出区域2进行探测，第二输出区域2的信噪比采用下式(2)表示：
SNR＝S/C     (2)。
在步骤S406：根据所述输出区域对应的探测器的输出，得到所述激光雷达与目标物之间的距离。例如，根据飞行时间测距法计算TOF(Time of flight)时间，获取目标物与激光雷达间的距离。
本发明在激光雷达接收端的探测单元内根据环境光选择输出区域对回波进行接收，并基于上述方法对激光雷达进行测距。通过本发明的实施例，提高了激光雷达整体测距的信噪比，能够减少环境光对激光雷达测远性能的影响，同时节省了功耗。
最后应说明的是：以上所述仅为本发明的优选实施例而已，并不用于限制本发明，尽管参照前述实施例对本发明进行了详细的说明，对于本领域的技术人员来说，其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。
虽然本说明书实施例披露如上，但本说明书实施例并非限定于此。任何本领域技术人员，在不脱离本说明书实施例的精神和范围内，均可作各种更动与 修改，因此本说明书实施例的保护范围应当以权利要求所限定的范围为准。

Claims (13)

  1. 一种利用激光雷达探测的方法，所述激光雷达包括一探测部，所述探测部包括多个探测单元，其中，所述多个探测单元可对应一个或多个输出区域；所述方法包括以下步骤：
    a.根据当前的环境光信息，由所述探测部中选择一输出区域；所述输出区域包括一个或多个探测单元；
    b.获取该所选的所述输出区域的回波信息；
    c.根据该所选的输出区域的回波信息，进行探测。
  2. 根据权利要求1所述的方法，其中，所述方法进一步包括：
    -根据环境光信息，来确定至少一个比较阈值；
    其中，所述步骤a进一步包括：
    a'根据所述当前的环境光信息以及所述至少一个比较阈值，由所述探测部中选择一输出区域。
  3. 根据权利要求2所述的方法，其中，所述至少一个比较阈值包括第一光强阈值和第二光强阈值，其中，所述第一比较阈值大于等于所述第二比较阈值，所述一个或多个输出区域至少包括第一输出区域和第二输出区域，所述第一输出区域小于第二输出区域，所述步骤a'进一步包括：
    当所述当前的环境光的光强大于所述第一光强阈值时，选择面积较小的所述第二输出区域；
    当所述当前的环境光的光强小于所述第二光强阈值时，选择面积较大的所述第一输出区域。
  4. 根据权利要求3所述的方法，其中，所述第一比较阈值等于所述第二比较阈值。
  5. 根据权利要求1至4中任一项所述的方法，其中，所述方法进一步包括以下步骤：
    根据一个或多个历史光斑区域，确定所述一个或多个输出区域。
  6. 根据权利要求5所述的方法，其中，所述方法进一步包括：
    获取光斑区域；
    根据所述光斑区域，确定与所述光斑区域对应的至少一个输出区域；
    所述步骤a进一步包括：
    a"根据所述当前的环境光信息，由所述至少一个输出区域中选择一输出区域，所选择的所述输出区域包含于所述光斑区域中。
  7. 根据权利要求6所述的方法，其中，所述方法进一步包括：
    -根据新光斑区域来更新所述一个或多个输出区域。
  8. 根据权利要求1至7所述的方法，其中，所述探测单元可包括多个探测器。
  9. 根据权利要求8所述的方法，其中，所述探测器为单光子雪崩二极管(SPAD)。
  10. 根据权利要求9所述的方法，其中，所述探测单元为SPADs阵列或硅光电增强管(SiPM)。
  11. 根据权利要求1-10中任一项所述的探测方法，还包括以下步骤：
    根据所述输出区域对应的探测器的输出，得到所述激光雷达与目标物之间的距离。
  12. 一种激光雷达，其中，所述激光雷达包括：
    发射单元，所述发射单元配置成发射探测激光束用于探测目标物；
    所述探测部，配置成接收所述探测激光束在目标物上反射的回波并输出回波信号；
    处理单元，所述处理单元与所述探测部耦接，所述处理单元并配置成使用如权利要求1-11中任一项所述的探测方法，来控制所述探测部并获得其所输出的回波信号。
  13. 根据权利要求11所述的激光雷达，其中，所述处理单元还用于：
    根据所述输出信号，计算所述激光雷达与目标物之间的距离。
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