WO2021037211A1 - 激光雷达系统的测距方法以及激光雷达系统 - Google Patents

激光雷达系统的测距方法以及激光雷达系统 Download PDF

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Publication number
WO2021037211A1
WO2021037211A1 PCT/CN2020/112138 CN2020112138W WO2021037211A1 WO 2021037211 A1 WO2021037211 A1 WO 2021037211A1 CN 2020112138 W CN2020112138 W CN 2020112138W WO 2021037211 A1 WO2021037211 A1 WO 2021037211A1
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Prior art keywords
pulse
energy
echo signal
obstacle
time difference
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PCT/CN2020/112138
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English (en)
French (fr)
Inventor
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 EP20856659.6A priority Critical patent/EP3995859A4/en
Publication of WO2021037211A1 publication Critical patent/WO2021037211A1/zh
Priority to US17/553,064 priority patent/US20220120897A1/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
    • 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
    • G01S17/04—Systems determining the presence of a target
    • 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
    • G01S17/42—Simultaneous measurement of distance and other co-ordinates
    • 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
    • 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
    • G01S7/484—Transmitters
    • 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
    • G01S7/4868—Controlling received signal intensity or exposure of sensor
    • 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
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
    • G01S17/931—Lidar systems specially adapted for specific applications for anti-collision purposes of land vehicles

Definitions

  • the invention relates to the field of distance measurement, in particular to a distance measurement method of a laser radar system and a laser radar system.
  • Lidar As a high-precision active three-dimensional imaging sensor, Lidar has the characteristics of high resolution and less environmental interference. Lidar calculates distance by measuring the flight time of laser pulses in space. Normally, the rotating lidar emits laser light from the optical window. While the lidar rotates, it emits laser light in different vertical directions to obtain three-dimensional distance information. The ranging performance of lidar depends to a large extent on the energy level of the laser pulse. At the same time, lidar needs to comply with Class 1 defined by the laser product safety standard IEC 60825-1, that is, eye safety.
  • the laser energy threshold corresponding to human eye safety is related to the number of laser pulses received by the human eye per unit time. When the number of laser pulses received by the human eye per unit time is large, the laser single pulse energy threshold is relatively low. Current solutions to this restriction include: 1) using auxiliary light sources; 2) controlling the relative separation of pulse spaces with close timing.
  • the method of using auxiliary light sources includes: using an auxiliary light source that emits in the same direction as the ranging light source (for example, the ranging light source is in the infrared band and the auxiliary light source is in the visible light band) to enable the human eye to actively avoid it; or using the distance measurement light source.
  • auxiliary light sources with light sources that are not in the same direction carry out early warning detection.
  • the above methods will increase the complexity of the system structure.
  • the method of controlling the relative separation of the pulse space with close timing is mostly suitable for single-pulse laser radar.
  • the current laser radar needs to transmit a pulse sequence every time in order to achieve anti-interference. Therefore, the above method cannot effectively solve the problem of human eye safety.
  • the purpose of the present invention is to provide a laser radar system ranging method and a laser radar system.
  • the laser radar satisfies the human eye safety requirements, and at the same time improves the single pulse energy threshold of the ranging pulse.
  • the long-distance measurement performance is guaranteed, and the implementation cost is low.
  • the invention discloses a distance measurement method of a lidar system, which includes:
  • the second pulse of the second energy is emitted in the emission direction of the first pulse corresponding to the judged echo signal, and the second energy is greater than the first energy, when it is judged that the preset distance There is an obstacle inside, and the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined echo signal.
  • judging whether there is an obstacle within a preset distance based on the echo signal including:
  • the second pulse when the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined echo signal, the second pulse is deviated from the emission direction of the first pulse corresponding to the determined echo signal by a predetermined angle The second pulse is also not emitted in the direction within the range.
  • the first pulse is a first single pulse or a first pulse sequence
  • the second pulse is a second single pulse or a second pulse sequence.
  • the energy of the first single pulse is the first energy
  • the first pulse is the first pulse sequence
  • the sum of the energy of all single pulses in the first pulse sequence is the first pulse. energy
  • the energy of the second single pulse is the second energy; when the second pulse is the second pulse sequence, the sum of the energy of all the single pulses in the second pulse sequence is the second energy.
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the energy of the first single pulse ;
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of all single pulses in the second pulse sequence The sum is greater than the sum of the energy of all single pulses in the first pulse sequence;
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the sum of the energy of all single pulses in the second pulse sequence is greater than the first single pulse energy of;
  • the first pulse is the first pulse sequence and the second pulse is the second single pulse
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the first pulse sequence The sum of the energy of all single pulses in.
  • the invention discloses a lidar system, which includes a transmitting unit, a receiving unit, a signal processing unit and a control unit;
  • the control unit controls the transmitting unit to transmit the first pulse of the first energy
  • the receiving unit receives the echo signal corresponding to the first pulse
  • the signal processing unit judges whether there is an obstacle within the preset distance according to the echo signal
  • the control unit controls the transmitting unit to transmit a second pulse of the second energy in the transmitting direction of the first pulse corresponding to the judged echo signal, and the second energy is greater than
  • the control unit controls the transmitting unit not to transmit the second pulse in the transmitting direction of the first pulse corresponding to the determined echo signal.
  • the signal processing unit determines whether there is an obstacle within the preset distance according to the echo signal, including:
  • control unit controls the transmitting unit not to transmit the second pulse in the transmitting direction of the first pulse corresponding to the determined echo signal
  • the control unit controls the transmitting unit to deviate from the determined echo signal.
  • the second pulse is not emitted in the direction within the predetermined angle range of the emission direction of the corresponding first pulse.
  • the first pulse is a first single pulse or a first pulse sequence
  • the second pulse is a second single pulse or a second pulse sequence.
  • the energy of the first single pulse is the first energy
  • the first pulse is the first pulse sequence
  • the sum of the energy of all single pulses in the first pulse sequence is the first pulse. energy
  • the energy of the second single pulse is the second energy; when the second pulse is the second pulse sequence, the sum of the energy of all the single pulses in the second pulse sequence is the second energy.
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the energy of the first single pulse ;
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of all single pulses in the second pulse sequence The sum is greater than the sum of the energy of all single pulses in the first pulse sequence;
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the sum of the energy of all single pulses in the second pulse sequence is greater than the first single pulse energy of;
  • the first pulse is the first pulse sequence and the second pulse is the second single pulse
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the first pulse sequence The sum of the energy of all single pulses in.
  • the lidar system first transmits one or more lower energy first pulses, receives one or more echo signals corresponding to the one or more first pulses, and determines the preset based on the one or more echo signals Whether there are obstacles within the distance.
  • the eye safety threshold of lidar is often limited to close distances. Therefore, when it is judged that there is no obstacle within the preset distance, in the direction of the first pulse corresponding to the judged echo signal When it is determined that there is an obstacle within the preset distance, the second pulse is not transmitted in the transmitting direction of the first pulse corresponding to the determined echo signal.
  • the lidar system does not need to use auxiliary light sources, and does not increase the complexity of the system structure; the energy of the first pulse is lower, which meets the safety requirements of human eyes; the energy of the second pulse is higher, which improves the single pulse energy of the ranging pulse.
  • the threshold value ensures the long-distance measurement performance; the realization cost of the laser radar system ranging is low.
  • the lidar system can calculate the time difference between the receiving time of each echo signal and the emission time of the corresponding first pulse, and determine whether there is an obstacle within the preset distance by judging whether the time difference is greater than the first preset time difference. Therefore, it can be easily judged whether there is an obstacle within the preset distance, and the accuracy is high.
  • the lidar system When the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined echo signal, the lidar system deviates from the predetermined angle range of the emission direction of the first pulse corresponding to the determined echo signal The second pulse is also not emitted in one or more directions within. Therefore, when the obstacle is a person, the lidar system can avoid the range of the human eye to further ensure the safety of the human eye.
  • Fig. 1 is a flowchart of a ranging method of a lidar system according to a first embodiment of the present invention
  • FIG. 2 is a schematic diagram of judging whether there is an obstacle within a preset distance according to the first embodiment of the present invention
  • FIG. 3 is a schematic diagram showing that the second pulse is not emitted in one or more directions within a predetermined angle range from the emission direction of the first pulse corresponding to the determined echo signal according to the first embodiment of the present invention
  • FIG. 4 is a schematic diagram of the first pulse and the second pulse according to the first embodiment of the present invention.
  • Fig. 5 is a structural diagram of a lidar system according to a second embodiment of the present invention.
  • the first embodiment of the present invention relates to a ranging method of a lidar system.
  • Fig. 1 is a flowchart of a ranging method of a lidar system according to a first embodiment of the present invention.
  • the ranging method of the lidar system includes:
  • Step 102 Transmit a first pulse of first energy
  • Step 104 Receive an echo signal corresponding to the first pulse
  • Step 106 Determine whether there is an obstacle within a preset distance based on the echo signal
  • Step 108 When it is judged that there is no obstacle within the preset distance, a second pulse of the second energy is transmitted in the transmitting direction of the first pulse corresponding to the judged echo signal, and the second energy is greater than the first energy. There is an obstacle within the preset distance, and the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined echo signal.
  • the lidar system can emit laser pulses within a certain angle range.
  • the horizontal field of view angle of the lidar system may be 360°
  • the vertical field of view angle may be 40° (for example, from -25° to +15°). It can be understood that the horizontal field of view and the vertical field of view of the lidar system can be adjusted according to actual needs and are not limited here.
  • the lidar system can emit one or more first pulses of first energy in one or more directions, and each first pulse of first energy corresponds to a vertical field of view direction.
  • first pulse of the first energy can be emitted in sequence along the vertical field of view (-25° to +15°) (that is, only one first pulse of the first energy is emitted at a time. One pulse).
  • the lidar system rotates to 45° in the horizontal direction, it can simultaneously emit multiple first pulses of the first energy along the vertical field of view range (-25° to +15°), such as four and four first pulses.
  • the vertical field of view direction of the first pulse of energy should be separated as much as possible to reduce the possibility of it being received by the human eye at the same time.
  • the lidar can also emit one or more first pulses of the first energy within a partial range of the vertical field of view (for example, -5° to +5°). It can be understood that the emission direction and number of the first pulses can be adjusted according to actual needs, and are not limited here.
  • the lidar system transmits four first pulses of the first energy in the horizontal direction of 45° and the vertical direction of -25° to +15°, and receives four first pulses corresponding to the four first pulses.
  • the four echo signals it is possible to determine whether there are obstacles within the preset distance. If it is determined that there are no obstacles within the preset distance according to the two echo signals, the second pulse of the second energy is emitted in the emission direction of the first pulse corresponding to the determined two echo signals, The second energy is greater than the first energy. If it is determined that there is an obstacle within the preset distance based on the remaining two echo signals, the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined two echo signals.
  • the lidar system first transmits one or more lower energy first pulses, receives one or more echo signals corresponding to the one or more first pulses, and determines the preset based on the one or more echo signals Whether there are obstacles within the distance. Since the laser power entering the pupil of the human eye will attenuate with distance, according to human eye safety standards, the eye safety threshold of lidar is often limited to close distances. Therefore, when it is judged that there are no obstacles in the preset relatively short distance, The second pulse of higher energy is emitted in the transmitting direction of the first pulse corresponding to the determined echo signal. When it is determined that there is an obstacle within the preset shorter distance, the first pulse corresponding to the determined echo signal is emitted. The second pulse is not emitted in the direction of pulse emission.
  • the lidar system does not need to use auxiliary light sources, and does not increase the complexity of the system structure; the energy of the first pulse is lower, which meets the safety requirements of human eyes; the energy of the second pulse is higher, which improves the single pulse energy of the ranging pulse.
  • the threshold value ensures the long-distance measurement performance; the realization cost of the laser radar system ranging is low.
  • Fig. 2 is a schematic diagram of judging whether there is an obstacle within a preset distance according to the first embodiment of the present invention.
  • the lidar system can be installed on the vehicle, for example, on the top of the vehicle.
  • the horizontal field of view of the lidar system can be 360°, and the lidar system can also be installed on the vehicle.
  • the dotted line in Figure 2 is the preset distance.
  • the preset distance can be determined according to factors such as the energy of the first pulse, the size of the light spot, and the laser eye safety threshold.
  • the preset distance can be 1.5m, and the dotted line in Figure 2 is 1.5m from the center of the lidar system.
  • the lidar system can transmit two first pulses of the first energy to different vertical angle directions at the same time, and receive two echo signals corresponding to the two first pulses. According to the two echo signals, it is determined whether there is an obstacle within the preset distance. If it is determined that there is no obstacle within 1.5m based on one of the echo signals, a second pulse of the second energy is emitted in the emission direction of the first pulse corresponding to the determined echo signal, and the second energy is greater than the first energy. If it is determined that there is an obstacle within 1.5 m based on the other echo signal, the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined echo signal.
  • judging whether there is an obstacle within the preset distance according to the echo signal including:
  • the lidar system can transmit two first pulses of the first energy to different vertical angle directions at the same time, and receive two echo signals corresponding to the two first pulses. Calculate the time difference between the reception time of each echo signal and the transmission time of the corresponding first pulse. If the time difference between the receiving time of one of the echo signals and the transmitting time of the corresponding first pulse is greater than 10 ns, it is determined that there is no obstacle within the preset distance (for example, 1.5 m), and it is in phase with the determined echo signal. The second pulse of the second energy is emitted in the emission direction of the corresponding first pulse, and the second energy is greater than the first energy.
  • the time difference between the receiving time of the other echo signal and the transmitting time of the corresponding first pulse is less than or equal to 10ns, it is determined that there is an obstacle within the preset distance (for example, 1.5m), and the echo The second pulse is not emitted in the emission direction of the first pulse corresponding to the signal.
  • the lidar system can calculate the time difference between the receiving time of each echo signal and the emission time of the corresponding first pulse, and determine whether there is an obstacle within the preset distance by judging whether the time difference is greater than the first preset time difference. Therefore, it can be easily judged whether there is an obstacle within the preset distance, and the accuracy is high.
  • FIG. 3 is a schematic diagram showing that the second pulse is not emitted in one or more directions within a predetermined angle range from the emission direction of the first pulse corresponding to the determined echo signal according to the first embodiment of the present invention.
  • the arrow direction is the emission direction of the first pulse corresponding to the determined echo signal.
  • the second pulse when the second pulse is not emitted in the emission direction of the first pulse, the second pulse is not emitted in one or more directions within a predetermined angle A range from the emission direction of the first pulse. Therefore, the light source of the lidar system can be taken as the vertex, the emission direction of the first pulse is the cone axis, and the predetermined angle A is the half angle of the cone to form a cone, so that it will not emit in one or more directions within the cone.
  • the second pulse when the second pulse is not emitted in the emission direction of the first pulse, the second pulse is not emitted in one or more directions within a predetermined angle A range from the emission direction of the first pulse. Therefore, the light source of the lidar system can be taken as the vertex, the emission direction of the first pulse is the cone axis, and the predetermined angle A is the half angle of the cone to form a cone, so that it will not emit in one or more directions
  • the second pulse when the second pulse is not emitted in the emission direction of the plurality of first pulses, the second pulse is not emitted in one or more directions within the predetermined angle A range from the emission direction of the plurality of first pulses. Therefore, it is possible to take the light source of the lidar system as the vertex, the emission direction of the multiple first pulses as the cone axis, and the predetermined angle A as the half angle of the cone to form multiple cones, respectively, in one or more directions within the multiple cones.
  • the second pulse is also not emitted.
  • one or more directions in the cone may be in the same vertical plane as the emission direction of the first pulse. It can be understood that one or more directions in the cone can be adjusted according to actual needs, and it is not limited here.
  • the second pulse may not be emitted in all directions in the cone.
  • the predetermined angle A may be a value indicating the horizontal or vertical angular resolution, for example, 0.1°. It can be understood that the predetermined angle A can be adjusted according to actual needs and is not limited here.
  • the emission direction of the first pulse corresponding to the determined echo signal is 45° in the horizontal direction and 0° in the vertical direction.
  • the second pulse is not emitted in this direction, it is 45° in the horizontal direction and the vertical direction ⁇
  • the second pulse is also not emitted in one or more directions within the range of 0.1° to +0.1°.
  • the emission directions of the three first pulses corresponding to the determined echo signal are 45° in the horizontal direction and 0° in the vertical direction, 45° in the horizontal direction and -10° in the vertical direction, and 45° in the horizontal direction and vertical direction. +10°, when the second pulse is not emitted in three directions, 45° in the horizontal direction and within the range of -0.1° to +0.1° in the vertical direction, 45° in the horizontal direction and -10.1° to -9.9° in the vertical direction.
  • the second pulse is also not emitted in one or more directions within the range of 45° in the horizontal direction and +9.9° to +10.1° in the vertical direction.
  • the lidar system When the second pulse is not emitted in the emission direction of the first pulse corresponding to the determined echo signal, the lidar system deviates from the predetermined angle range of the emission direction of the first pulse corresponding to the determined echo signal The second pulse is also not emitted in one or more directions within. Therefore, when the obstacle is a person, the lidar system can avoid the range of the human eye to further ensure the safety of the human eye.
  • Fig. 4 is a schematic diagram of a first pulse and a second pulse according to the first embodiment of the present invention.
  • the first pulse may be a first single pulse or a first pulse sequence
  • the second pulse may be a second single pulse or a second pulse sequence.
  • the energy of the first single pulse is the first energy
  • the first pulse is the first pulse sequence
  • the sum of the energy of all single pulses in the first pulse sequence is the first energy
  • the energy of the second single pulse is the second energy; when the second pulse is the second pulse sequence, the sum of the energy of all the single pulses in the second pulse sequence is the second energy.
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the energy of the first single pulse;
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of all single pulses in the second pulse sequence The sum is greater than the sum of the energy of all single pulses in the first pulse sequence;
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the sum of the energy of all single pulses in the second pulse sequence is greater than the first single pulse energy of;
  • the first pulse is the first pulse sequence and the second pulse is the second single pulse
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the first pulse sequence The sum of the energy of all single pulses in.
  • the pulse sequence may include two or more single pulses. It can be understood that the number of single pulses in the pulse sequence can be adjusted according to actual needs and is not limited here.
  • the first pulse is the first single pulse
  • the second pulse is the second single pulse
  • the energy of the first single pulse is the first energy
  • the energy of the second single pulse is the second energy.
  • the first energy is less than or equal to the laser eye safety threshold
  • the second energy is greater than the first energy.
  • the second energy may be more than 10 times the first energy. It can be understood that the ratio of the second energy to the first energy can be adjusted according to actual needs and is not limited here.
  • the time difference between the emission time of the first single pulse and the emission time of the second single pulse is the second preset time difference t1.
  • the second preset time difference t1 is greater than or equal to the first preset time difference.
  • the second preset time difference t1 can be determined according to the first preset time difference and the signal processing speed of the lidar system.
  • the first pulse is the first pulse sequence
  • the second pulse is the second pulse sequence
  • the sum of the energy of all single pulses in the first pulse sequence is the first energy
  • the second pulse sequence is The sum of the energy of all single pulses is the second energy
  • the first energy is less than or equal to the laser eye safety threshold
  • the second energy is greater than the first energy.
  • the second energy may be more than 10 times the first energy. It can be understood that the ratio of the second energy to the first energy can be adjusted according to actual needs and is not limited here.
  • the energy of each single pulse in the first pulse sequence may be the same or different, and the energy of each single pulse in the second pulse sequence may be the same or different.
  • the time difference between the emission time of the last single pulse in the first pulse sequence and the emission time of the first single pulse in the second pulse sequence is the second preset time difference t1.
  • the second preset time difference t1 is greater than or equal to the first preset time difference.
  • the second preset time difference t1 may be determined according to the first preset time difference and the signal processing speed of the lidar system.
  • time interval t 2 between each single pulse in the first pulse sequence and the time interval t 3 between each single pulse in the second pulse sequence may be the same or different.
  • the first pulse is a first single pulse
  • the second pulse is a second pulse sequence
  • the energy of the first single pulse is the first energy
  • the sum of the energies of all single pulses in the second pulse sequence is The second energy
  • the first energy is less than or equal to the laser eye safety threshold
  • the second energy is greater than the first energy.
  • the second energy may be more than 10 times the first energy. It can be understood that the ratio of the second energy to the first energy can be adjusted according to actual needs and is not limited here.
  • the energy of each single pulse in the second pulse sequence may be the same or different.
  • the first pulse is the first pulse sequence
  • the second pulse is the second single pulse
  • the sum of the energy of all single pulses in the first pulse sequence is the first energy
  • the energy of the second single pulse is The second energy
  • the first energy is less than or equal to the laser eye safety threshold
  • the second energy is greater than the first energy.
  • the second energy may be more than 10 times the first energy. It can be understood that the ratio of the second energy to the first energy can be adjusted according to actual needs and is not limited here.
  • the energy of each single pulse in the first pulse sequence may be the same or different.
  • Fig. 5 is a structural diagram of a lidar system according to a second embodiment of the present invention.
  • the lidar system includes a transmitting unit, a receiving unit, a signal processing unit, and a control unit;
  • the control unit controls the transmitting unit to transmit the first pulse of the first energy
  • the receiving unit receives the echo signal corresponding to the first pulse
  • the signal processing unit judges whether there is an obstacle within the preset distance according to the echo signal
  • the control unit controls the transmitting unit to transmit a second pulse of the second energy in the transmitting direction of the first pulse corresponding to the judged echo signal, and the second energy is greater than
  • the control unit controls the transmitting unit not to transmit the second pulse in the transmitting direction of the first pulse corresponding to the determined echo signal.
  • the signal processing unit determines whether there is an obstacle within the preset distance according to the echo signal, including:
  • control unit controls the transmitting unit not to transmit the second pulse in the transmitting direction of the first pulse corresponding to the determined echo signal
  • the control unit controls the transmitting unit to deviate from the determined echo signal.
  • the second pulse is not emitted in a direction within a predetermined angle range of the emission direction of the first pulse.
  • the first pulse is a first single pulse or a first pulse sequence
  • the second pulse is a second single pulse or a second pulse sequence
  • the energy of the first single pulse is the first energy
  • the first pulse is the first pulse sequence
  • the sum of the energy of all single pulses in the first pulse sequence is the first energy
  • the energy of the second single pulse is the second energy; when the second pulse is the second pulse sequence, the sum of the energy of all the single pulses in the second pulse sequence is the second energy.
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the energy of the first single pulse;
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of all single pulses in the second pulse sequence The sum is greater than the sum of the energy of all single pulses in the first pulse sequence;
  • the energy of the first single pulse is less than or equal to the laser eye safety threshold, and the sum of the energy of all single pulses in the second pulse sequence is greater than the first single pulse energy of;
  • the first pulse is the first pulse sequence and the second pulse is the second single pulse
  • the sum of the energy of all single pulses in the first pulse sequence is less than or equal to the laser eye safety threshold, and the energy of the second single pulse is greater than the first pulse sequence The sum of the energy of all single pulses in.
  • the first embodiment is a method embodiment corresponding to this embodiment, and this embodiment can be implemented in cooperation with the first embodiment.
  • the related technical details mentioned in the first embodiment are still valid in this embodiment, and in order to reduce repetition, they will not be repeated here.
  • the related technical details mentioned in this embodiment can also be applied in the first embodiment.
  • each method implementation manner of the present invention can be implemented in software, hardware, firmware, and the like.
  • the instruction code can be stored in any type of computer accessible memory (for example, permanent or modifiable, volatile or non-volatile, solid-state Or non-solid, fixed or replaceable media, etc.).
  • the memory can be, for example, programmable array logic (Programmable Array Logic, "PAL"), random access memory (Random Access Memory, "RAM”), and programmable read-only memory (Programmable Read Only Memory, "PROM” for short).
  • ROM Read-Only Memory
  • EEPROM Electrically Erasable Programmable ROM
  • magnetic disks optical discs
  • digital versatile discs Digital Versatile Disc , Referred to as "DVD" and so on.
  • each unit/module mentioned in each device embodiment of the present invention is a logical unit/module.
  • a logical unit can be a physical unit, or a part of a physical unit, or It is realized by a combination of multiple physical units, and the physical realization of the logical units themselves is not the most important.
  • the combination of functions implemented by these logical units is the key to solving the technical problem proposed by the present invention.
  • the foregoing device implementations of the present invention do not introduce units that are not closely related to solving the technical problems proposed by the present invention. This does not mean that there are no other devices in the foregoing device implementations. unit.

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Abstract

一种涉及测距领域，特别涉及激光雷达系统的测距方法以及激光雷达系统。激光雷达系统的测距方法，包括：发射第一能量的第一脉冲(102)；接收与第一脉冲相对应的回波信号(104)；根据回波信号，判断预设距离内是否有障碍物(106)；当判断预设距离内没有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量，当判断预设距离内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲(108)。因此能在不增加系统结构复杂度的前提下，使激光雷达满足人眼安全要求，同时提升了测距脉冲的单脉冲能量阈值，保证了测远性能，降低了成本。

Description

激光雷达系统的测距方法以及激光雷达系统 技术领域
本发明涉及测距领域，特别涉及激光雷达系统的测距方法以及激光雷达系统。
背景技术
激光雷达作为一种高精度主动三维成像传感器，具有分辨率高、受环境干扰少的特点。激光雷达通过测量激光脉冲在空间中的飞行时间来计算距离。通常情况下旋转式激光雷达从光学窗口发射激光，激光雷达一边旋转，一边朝不同垂直方向发射激光，从而获得三维距离信息。激光雷达的测距性能在很大程度上取决于激光脉冲的能量高低。同时，激光雷达需要符合激光产品安全标准IEC 60825-1所定义的Class 1等级，即人眼安全。人眼安全所对应的激光能量阈值与单位时间内人眼接收到的激光脉冲数有关，当单位时间内人眼接收到的激光脉冲数较多时，则激光单脉冲能量阈值相对较低。针对该制约目前的解决方案包括：1)采用辅助光源；2)控制时序接近的脉冲空间相对分离。
对于采用辅助光源的方式，包括：采用与测距光源不同波长(如测距光源为红外波段，辅助光源为可见光波段)同向发射的辅助光源，使人眼进行主动规避；或者采用与测距光源非同向(如在测距光源外围)的辅助光源进行预警探测。但是，上述方式都会增加系统结构的复杂度。
对于控制时序接近的脉冲空间相对分离的方式，多适用于单脉冲发射激光雷达，然而目前激光雷达为实现抗干扰需要每次进行脉冲序列发射。因此，上述方式并不能有效解决人眼安全的问题。
发明内容
本发明的目的在于提供激光雷达系统的测距方法以及激光雷达系统，在不增加系统结构复杂度的前提下，激光雷达满足了人眼安全要求，同时提升了测距脉冲的单脉冲能量阈值，保证了测远性能，实现成本低。
本发明公开了一种激光雷达系统的测距方法，包括：
发射第一能量的第一脉冲；
接收与第一脉冲相对应的回波信号；
根据回波信号，判断预设距离内是否有障碍物；
当判断预设距离内没有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量，当判断预设距离内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
可选地，根据回波信号，判断预设距离内是否有障碍物，包括：
计算回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差；
判断时间差是否大于第一预设时间差；
当判断时间差大于第一预设时间差，预设距离内没有障碍物，当判断时间差小于等于第一预设时间差，预设距离内有障碍物。
可选地，当在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲时，在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的方向上也不发射第二脉冲。
可选地，第一脉冲为第一单脉冲或第一脉冲序列，第二脉冲为第二单脉冲或第二脉冲序列。
可选地，当第一脉冲为第一单脉冲，第一单脉冲的能量为第一能量；当第一脉冲为第一脉冲序列，第一脉冲序列中的所有单脉冲的能量和为第一能量；
当第二脉冲为第二单脉冲，第二单脉冲的能量为第二能量；当第二脉冲为第二脉冲序列，第二脉冲序列中的所有单脉冲的能量和为第二能量。
可选地，当第一脉冲为第一单脉冲，第二脉冲为第二单脉冲，第一单脉冲的能量小于等于激光人眼安全阈值，第二单脉冲的能量大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二脉冲序列，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一脉冲序列中的所有单脉冲的能量和；
当第一脉冲为第一单脉冲，第二脉冲为第二脉冲序列，第一单脉冲的能量小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二单脉冲，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二单脉冲的能量大于第一脉冲序列中的所有单脉冲的能量和。
本发明公开了一种激光雷达系统，包括发射单元、接收单元、信号处理单元和控制单元；
控制单元控制发射单元发射第一能量的第一脉冲；
接收单元接收与第一脉冲相对应的回波信号；
信号处理单元根据回波信号，判断预设距离内是否有障碍物；
当判断信号处理单元判断预设距离内没有障碍物，控制单元控制发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量，当判断信号处理单元判断预设距离内有障碍物，控制单元控制发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
可选地，信号处理单元根据回波信号，判断预设距离内是否有障碍物，包括：
计算回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差；
判断时间差是否大于第一预设时间差；
当判断时间差大于第一预设时间差，预设距离内没有障碍物，当判断时间差小于等于第一预设时间差，预设距离内有障碍物。
可选地，当控制单元控制发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲时，控制单元控制发射单元在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的方向上也不发射第二脉冲。
可选地，第一脉冲为第一单脉冲或第一脉冲序列，第二脉冲为第二单脉冲或第二脉冲序列。
可选地，当第一脉冲为第一单脉冲，第一单脉冲的能量为第一能量；当第一脉冲为第一脉冲序列，第一脉冲序列中的所有单脉冲的能量和为第一能量；
当第二脉冲为第二单脉冲，第二单脉冲的能量为第二能量；当第二脉冲为第二脉冲序列，第二脉冲序列中的所有单脉冲的能量和为第二能量。
可选地，当第一脉冲为第一单脉冲，第二脉冲为第二单脉冲，第一单脉冲的能量小于等于激光人眼安全阈值，第二单脉冲的能量大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二脉冲序列，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一脉冲序列中的所有单脉冲的能量和；
当第一脉冲为第一单脉冲，第二脉冲为第二脉冲序列，第一单脉冲的能量小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二单脉冲，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二单脉冲的能量大于第一脉冲序列中的所有单脉冲的能量和。
本发明与现有技术相比，主要区别及其效果在于：
激光雷达系统首先发射一个或多个较低能量的第一脉冲，接收与一个或多个第一脉冲相对应的一个或多个回波信号，并且根据一个或多个回波信号，判断预设距离内是否有障碍物。由于根据人眼安全标准，激光雷达的人眼安全阈值往往受限于近距离处，因此当判断预设距离内没有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上发射较高能量的第二脉冲，当判断预设距离内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。因此，激光雷达系统无需采用辅助光源，不增加系统结构的复杂度；第一脉冲的能量较低，满足了人眼安全要求；第二脉冲的能量较高，提升了测距脉冲的单脉冲能量阈值，保证了测远性能；激光雷达系统测距的实现成本低。
激光雷达系统可以计算每个回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差，通过判断时间差是否大于第一预设时间差来判断预设距离内是否有障碍物。因此，可以方便地判断预设距离内是否有障碍物，准确性高。
当在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲时，激光雷达系统在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的一个或多个方向上也不发射第二脉冲。因此，当障碍物为人时，激光雷达系统可以避开人眼的范围，进一步保证人眼安全。
附图说明
图1是根据本发明第一实施方式的激光雷达系统的测距方法的流程图；
图2是根据本发明第一实施方式的判断预设距离内是否有障碍物的示意图；
图3是根据本发明第一实施方式的在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的一个或多个方向上也不发射第二脉冲的示意图；
图4是根据本发明第一实施方式的第一脉冲和第二脉冲的示意图；
图5是根据本发明第二实施方式的激光雷达系统的结构图。
具体实施方式
为使本发明实施例的目的和技术方案更加清楚，下面将结合本发明实施例的附图，对本发明实施例的技术方案进行清楚、完整地描述。显然，所描述的实施例是本发明的一部分实施例，而不是全部的实施例。基于所描述的本发明的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明的第一实施方式涉及一种激光雷达系统的测距方法。图1是根据本发明第一实施方式的激光雷达系统的测距方法的流程图。
具体地，如图1所示，激光雷达系统的测距方法，包括：
步骤102，发射第一能量的第一脉冲；
步骤104，接收与第一脉冲相对应的回波信号；
步骤106，根据回波信号，判断预设距离内是否有障碍物；
步骤108，当判断预设距离内没有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量，当判断预设距离内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
其中，激光雷达系统可以在一定角度范围内发射激光脉冲。例如，激光雷达系统的水平视场角可以为360°，垂直视场角可以为40°(例如，从-25°到+15°)。可以理解，激光雷达系统的水平视场角和垂直视场角可以根据实际需要进行调整，在此不受限制。
其中，激光雷达系统可以在一个或多个方向上发射一个或多个第一能量的第一脉冲，每个第一能量的第一脉冲和一个垂直视场角方向相对应。例如，激光雷达系统旋转到水平方向45°时，可以沿垂直视场角范围(-25°到+15°)依次发射第一能量的第一脉冲(即每次只发射一个第一能量的第一脉冲)。又例如，激光雷达系统旋转到水平方向45°时，可以沿垂直视场角范围(-25°到+15°)同时发射多个第一能量的第一脉冲，例如四个，四个第一能量的第一脉冲的垂直视场角方向应尽量分离，以减小其同时被人眼接收到的可能性。当然，激光雷达也可以在垂直视场角的部分范围内(如-5°到+5°)，发射一个或多个第一能量的第一脉冲。可以理解，第一脉冲的发射方向和数量可以根据实际需要进行调整，在此不受限制。
其中，例如，激光雷达系统在水平方向45°、垂直方向-25°至+15°的方向上发射了四个第一能量的第一脉冲，并且接收到与四个第一脉冲相对应的四个回波信号，则可以根据四个回波信号，分别判断预设距离内是否有障碍物。如果根据其中的两个回波信号，分别判断预设距离内没有障碍物，则在与所判断的两个回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量。如果根据剩余的两个回波信号，分别判断预设距离内有障碍物，则在与所判断的两个回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
激光雷达系统首先发射一个或多个较低能量的第一脉冲，接收与一个或多个第一脉冲相对应的一个或多个回波信号，并且根据一个或多个回波信号，判断预设距离内是否有障碍物。由于进入人眼瞳孔的激光功率会随着距离衰减，根据人眼安全标准，激光雷达的人眼安全阈值往往受限于近距离处，因此当判断预设较近距离内没有障碍物，在与所判断的 回波信号相对应的第一脉冲的发射方向上发射较高能量的第二脉冲，当判断预设较近距离内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。因此，激光雷达系统无需采用辅助光源，不增加系统结构的复杂度；第一脉冲的能量较低，满足了人眼安全要求；第二脉冲的能量较高，提升了测距脉冲的单脉冲能量阈值，保证了测远性能；激光雷达系统测距的实现成本低。
图2是根据本发明第一实施方式的判断预设距离内是否有障碍物的示意图。
具体地，如图2所示，激光雷达系统可以被设置在车辆上，例如被设置在车辆的顶部位置，激光雷达系统的水平视场角可以为360°，激光雷达系统也可以被设置在车辆的车体四周。图2中虚线为预设距离。预设距离可以根据第一脉冲的能量、光斑大小、激光人眼安全阈值等因素确定。例如，预设距离可以为1.5m，图2中的虚线距离激光雷达系统的中心为1.5m。
例如，激光雷达系统可以同时向不同垂直角度方向发射两个第一能量的第一脉冲，接收与两个第一脉冲相对应的两个回波信号。根据两个回波信号，分别判断预设距离内是否有障碍物。如果根据其中一个回波信号，判断1.5m内没有障碍物，则在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量。如果根据其中另一个回波信号，判断1.5m内有障碍物，则在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
其中，根据回波信号，判断预设距离内是否有障碍物，包括：
计算回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差；
判断时间差是否大于第一预设时间差；
当判断时间差大于第一预设时间差，预设距离内没有障碍物，当判断时间差小于等于第一预设时间差，预设距离内有障碍物。
其中，可以根据飞行时间法Δt＝2*d/c来计算第一预设时间差，Δt为第一预设时间差，d为预设距离，c为光速。例如，如果预设距离为1.5m，则第一预设时间差为10ns，从而根据一个或多个回波信号，判断预设距离内是否有障碍物。可以理解，第一预设时间差可以根据飞行时间和激光雷达系统的延时来共同决定。
例如，激光雷达系统可以同时向不同垂直角度方向发射两个第一能量的第一脉冲，接收与两个第一脉冲相对应的两个回波信号。计算每个回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差。如果其中一个回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差大于10ns，则判断预设距离(例如1.5m)内没有障碍物，在与所判 断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量。如果其中另一个回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差小于等于10ns，则判断预设距离(例如1.5m)内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
激光雷达系统可以计算每个回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差，通过判断时间差是否大于第一预设时间差来判断预设距离内是否有障碍物。因此，可以方便地判断预设距离内是否有障碍物，准确性高。
图3是根据本发明第一实施方式的在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的一个或多个方向上也不发射第二脉冲的示意图。
具体地，如图3所示，箭头方向为与所判断的回波信号相对应的第一脉冲的发射方向。其中，当在该第一脉冲的发射方向上不发射第二脉冲时，在偏离该第一脉冲的发射方向预定角度A范围内的一个或多个方向上也不发射第二脉冲。因此，可以以激光雷达系统的光源为顶点，该第一脉冲的发射方向为圆锥轴，预定角度A为圆锥半角，形成一个圆锥体，从而在该圆锥体内的一个或多个方向上也不发射第二脉冲。
其中，当在多个第一脉冲的发射方向上不发射第二脉冲时，分别在偏离多个第一脉冲的发射方向预定角度A范围内的一个或多个方向上也不发射第二脉冲。因此，可以以激光雷达系统的光源为顶点，多个第一脉冲的发射方向为圆锥轴，预定角度A为圆锥半角，形成多个圆锥体，从而分别在多个圆锥体内的一个或多个方向上也不发射第二脉冲。
其中，圆锥体内的一个或多个方向可以与第一脉冲的发射方向在同一垂直平面内。可以理解，圆锥体内的一个或多个方向可以根据实际需要进行调整，在此不受限制，例如可以在圆锥体内的所有方向上都不发射第二脉冲。
其中，预定角度A可以为指示水平或垂直角分辨率的值，例如0.1°。可以理解，预定角度A可以根据实际需要进行调整，在此不受限制。
例如，与所判断的回波信号相对应的第一脉冲的发射方向为水平方向45°且垂直方向0°，当在该方向上不发射第二脉冲时，在水平方向45°且垂直方向-0.1°至+0.1°范围内的一个或多个方向上也不发射第二脉冲。
例如，与所判断的回波信号相对应的三个第一脉冲的发射方向分别为水平方向45°且垂直方向0°、水平方向45°且垂直方向-10°、水平方向45°且垂直方向+10°，当在三个方向上不发射第二脉冲时，在水平方向45°且垂直方向-0.1°至+0.1°范围内、水平方向45°且垂直方向-10.1°至-9.9°范围内、水平方向45°且垂直方向+9.9°至+10.1°范围 内的一个或多个方向上也不发射第二脉冲。
当在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲时，激光雷达系统在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的一个或多个方向上也不发射第二脉冲。因此，当障碍物为人时，激光雷达系统可以避开人眼的范围，进一步保证人眼安全。
图4是根据本发明第一实施方式的第一脉冲和第二脉冲的示意图。
其中，第一脉冲可以为第一单脉冲或第一脉冲序列，第二脉冲可以为第二单脉冲或第二脉冲序列。
其中，当第一脉冲为第一单脉冲，第一单脉冲的能量为第一能量；当第一脉冲为第一脉冲序列，第一脉冲序列中的所有单脉冲的能量和为第一能量；
当第二脉冲为第二单脉冲，第二单脉冲的能量为第二能量；当第二脉冲为第二脉冲序列，第二脉冲序列中的所有单脉冲的能量和为第二能量。
其中，当第一脉冲为第一单脉冲，第二脉冲为第二单脉冲，第一单脉冲的能量小于等于激光人眼安全阈值，第二单脉冲的能量大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二脉冲序列，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一脉冲序列中的所有单脉冲的能量和；
当第一脉冲为第一单脉冲，第二脉冲为第二脉冲序列，第一单脉冲的能量小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二单脉冲，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二单脉冲的能量大于第一脉冲序列中的所有单脉冲的能量和。
其中，脉冲序列可以包括两个或多个单脉冲。可以理解，脉冲序列中的单脉冲的数量可以根据实际需要进行调整，在此不受限制。
具体地，如图4上方所示，第一脉冲为第一单脉冲，第二脉冲为第二单脉冲，第一单脉冲的能量为第一能量，第二单脉冲的能量为第二能量，并且第一能量小于等于激光人眼安全阈值，第二能量大于第一能量。例如，第二能量可以是第一能量的10倍以上。可以理解，第二能量与第一能量的比值可以根据实际需要进行调整，在此不受限制。
其中，第一单脉冲的发射时间与第二单脉冲的发射时间之间的时间差为第二预设时间差t1。第二预设时间差t1大于等于第一预设时间差，例如第二预设时间差t1可以根据第 一预设时间差以及激光雷达系统的信号处理速度等来确定。
具体地，如图4下方所示，第一脉冲为第一脉冲序列，第二脉冲为第二脉冲序列，第一脉冲序列中的所有单脉冲的能量和为第一能量，第二脉冲序列中的所有单脉冲的能量和为第二能量，并且第一能量小于等于激光人眼安全阈值，第二能量大于第一能量。例如，第二能量可以是第一能量的10倍以上。可以理解，第二能量与第一能量的比值可以根据实际需要进行调整，在此不受限制。
其中，第一脉冲序列中的每个单脉冲的能量可以相同也可以不相同，第二脉冲序列中的每个单脉冲的能量可以相同也可以不相同。
其中，第一脉冲序列中的最后一个单脉冲的发射时间与第二脉冲序列中的第一个单脉冲的发射时间之间的时间差为第二预设时间差t1。第二预设时间差t1大于等于第一预设时间差，例如第二预设时间差t1可以根据第一预设时间差以及激光雷达系统的信号处理速度等来确定。
其中，第一脉冲序列中的每个单脉冲之间的时间间隔t 2与第二脉冲序列中的每个单脉冲之间的时间间隔t 3可以相同，也可以不相同。
具体地，未图示的，第一脉冲为第一单脉冲，第二脉冲为第二脉冲序列，第一单脉冲的能量为第一能量，第二脉冲序列中的所有单脉冲的能量和为第二能量，并且第一能量小于等于激光人眼安全阈值，第二能量大于第一能量。例如，第二能量可以是第一能量的10倍以上。可以理解，第二能量与第一能量的比值可以根据实际需要进行调整，在此不受限制。
其中，第二脉冲序列中的每个单脉冲的能量可以相同也可以不相同。
具体地，未图示的，第一脉冲为第一脉冲序列，第二脉冲为第二单脉冲，第一脉冲序列中的所有单脉冲的能量和为第一能量，第二单脉冲的能量为第二能量，并且第一能量小于等于激光人眼安全阈值，第二能量大于第一能量。例如，第二能量可以是第一能量的10倍以上。可以理解，第二能量与第一能量的比值可以根据实际需要进行调整，在此不受限制。
其中，第一脉冲序列中的每个单脉冲的能量可以相同也可以不相同。
本发明的第二实施方式涉及一种激光雷达系统。图5是根据本发明第二实施方式的激光雷达系统的结构图。
具体地，如图5所示，激光雷达系统包括发射单元、接收单元、信号处理单元和控制单元；
控制单元控制发射单元发射第一能量的第一脉冲；
接收单元接收与第一脉冲相对应的回波信号；
信号处理单元根据回波信号，判断预设距离内是否有障碍物；
当判断信号处理单元判断预设距离内没有障碍物，控制单元控制发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，第二能量大于第一能量，当判断信号处理单元判断预设距离内有障碍物，控制单元控制发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲。
其中，信号处理单元根据回波信号，判断预设距离内是否有障碍物，包括：
计算回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差；
判断时间差是否大于第一预设时间差；
当判断时间差大于第一预设时间差，预设距离内没有障碍物，当判断时间差小于等于第一预设时间差，预设距离内有障碍物。
其中，当控制单元控制发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上不发射第二脉冲时，控制单元控制发射单元在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的方向上也不发射第二脉冲。
其中，第一脉冲为第一单脉冲或第一脉冲序列，第二脉冲为第二单脉冲或第二脉冲序列。
其中，当第一脉冲为第一单脉冲，第一单脉冲的能量为第一能量；当第一脉冲为第一脉冲序列，第一脉冲序列中的所有单脉冲的能量和为第一能量；
当第二脉冲为第二单脉冲，第二单脉冲的能量为第二能量；当第二脉冲为第二脉冲序列，第二脉冲序列中的所有单脉冲的能量和为第二能量。
其中，当第一脉冲为第一单脉冲，第二脉冲为第二单脉冲，第一单脉冲的能量小于等于激光人眼安全阈值，第二单脉冲的能量大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二脉冲序列，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一脉冲序列中的所有单脉冲的能量和；
当第一脉冲为第一单脉冲，第二脉冲为第二脉冲序列，第一单脉冲的能量小于等于激光人眼安全阈值，第二脉冲序列中的所有单脉冲的能量和大于第一单脉冲的能量；
当第一脉冲为第一脉冲序列，第二脉冲为第二单脉冲，第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，第二单脉冲的能量大于第一脉冲序列中的所有单脉 冲的能量和。
第一实施方式是与本实施方式相对应的方法实施方式，本实施方式可与第一实施方式互相配合实施。第一实施方式中提到的相关技术细节在本实施方式中依然有效，为了减少重复，这里不再赘述。相应地，本实施方式中提到的相关技术细节也可应用在第一实施方式中。
需要说明的是，本发明的各方法实施方式均可以以软件、硬件、固件等方式实现。不管本发明是以软件、硬件、还是固件方式实现，指令代码都可以存储在任何类型的计算机可访问的存储器中(例如永久的或者可修改的，易失性的或者非易失性的，固态的或者非固态的，固定的或者可更换的介质等等)。同样，存储器可以例如是可编程阵列逻辑(Programmable Array Logic，简称“PAL”)、随机存取存储器(Random Access Memory，简称“RAM”)、可编程只读存储器(Programmable Read Only Memory，简称“PROM”)、只读存储器(Read-Only Memory，简称“ROM”)、电可擦除可编程只读存储器(Electrically Erasable Programmable ROM，简称“EEPROM”)、磁盘、光盘、数字通用光盘(Digital Versatile Disc，简称“DVD”)等等。
需要说明的是，本发明各设备实施方式中提到的各单元/模块都是逻辑单元/模块，在物理上，一个逻辑单元可以是一个物理单元，也可以是一个物理单元的一部分，还可以以多个物理单元的组合实现，这些逻辑单元本身的物理实现方式并不是最重要的，这些逻辑单元所实现的功能的组合才是解决本发明所提出的技术问题的关键。此外，为了突出本发明的创新部分，本发明上述各设备实施方式并没有将与解决本发明所提出的技术问题关系不太密切的单元引入，这并不表明上述设备实施方式并不存在其它的单元。
需要说明的是，在本专利的权利要求和说明书中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
虽然通过参照本发明的某些优选实施方式，已经对本发明进行了图示和描述，但本领域的普通技术人员应该明白，可以在形式上和细节上对其作各种改变，而不偏离本发明的精神和范围。

Claims (10)

  1. 一种激光雷达系统的测距方法，其特征在于，包括：
    发射第一能量的第一脉冲；
    接收与所述第一脉冲相对应的回波信号；
    根据所述回波信号，判断预设距离内是否有障碍物；
    当判断所述预设距离内没有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，所述第二能量大于所述第一能量，当判断所述预设距离内有障碍物，在与所判断的回波信号相对应的第一脉冲的发射方向上不发射所述第二脉冲。
  2. 根据权利要求1所述的方法，其特征在于，根据所述回波信号，判断预设距离内是否有障碍物，包括：
    计算所述回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差；
    判断所述时间差是否大于第一预设时间差；
    当判断所述时间差大于所述第一预设时间差，所述预设距离内没有障碍物，当判断所述时间差小于等于所述第一预设时间差，所述预设距离内有障碍物。
  3. 根据权利要求1或2所述的方法，其特征在于，当在与所判断的回波信号相对应的第一脉冲的发射方向上不发射所述第二脉冲时，在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的方向上也不发射所述第二脉冲。
  4. 根据权利要求3所述的方法，其特征在于，所述第一脉冲为第一单脉冲或第一脉冲序列，所述第二脉冲为第二单脉冲或第二脉冲序列。
  5. 根据权利要求4所述的方法，其特征在于，当所述第一脉冲为所述第一单脉冲，所述第一单脉冲的能量为所述第一能量；当所述第一脉冲为所述第一脉冲序列，所述第一脉冲序列中的所有单脉冲的能量和为所述第一能量；
    当所述第二脉冲为所述第二单脉冲，所述第二单脉冲的能量为所述第二能量；当所述第二脉冲为所述第二脉冲序列，所述第二脉冲序列中的所有单脉冲的能量和为所述第二能量。
  6. 根据权利要求5所述的方法，其特征在于，当所述第一脉冲为所述第一单脉冲，所述第二脉冲为所述第二单脉冲，所述第一单脉冲的能量小于等于激光人眼安全阈值，所述第二单脉冲的能量大于所述第一单脉冲的能量；
    当所述第一脉冲为所述第一脉冲序列，所述第二脉冲为所述第二脉冲序列，所述第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，所述第二脉冲序列中的所有单脉冲的能量和大于所述第一脉冲序列中的所有单脉冲的能量和；
    当所述第一脉冲为所述第一单脉冲，所述第二脉冲为所述第二脉冲序列，所述第一单脉冲的能量小于等于激光人眼安全阈值，所述第二脉冲序列中的所有单脉冲的能量和大于所述第一单脉冲的能量；
    当所述第一脉冲为所述第一脉冲序列，所述第二脉冲为所述第二单脉冲，所述第一脉冲序列中的所有单脉冲的能量和小于等于激光人眼安全阈值，所述第二单脉冲的能量大于所述第一脉冲序列中的所有单脉冲的能量和。
  7. 一种激光雷达系统，其特征在于，包括发射单元、接收单元、信号处理单元和控制单元；
    所述控制单元控制所述发射单元发射第一能量的第一脉冲；
    所述接收单元接收与所述第一脉冲相对应的回波信号；
    所述信号处理单元根据所述回波信号，判断预设距离内是否有障碍物；
    当判断所述信号处理单元判断所述预设距离内没有障碍物，所述控制单元控制所述发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上发射第二能量的第二脉冲，所述第二能量大于所述第一能量，当判断所述信号处理单元判断所述预设距离内有障碍物，所述控制单元控制所述发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上不发射所述第二脉冲。
  8. 根据权利要求7所述的系统，其特征在于，所述信号处理单元根据所述回波信号，判断预设距离内是否有障碍物，包括：
    计算所述回波信号的接收时间与相对应的第一脉冲的发射时间之间的时间差；
    判断所述时间差是否大于第一预设时间差；
    当判断所述时间差大于所述第一预设时间差，所述预设距离内没有障碍物，当判断所述时间差小于等于所述第一预设时间差，所述预设距离内有障碍物。
  9. 根据权利要求7或8所述的系统，其特征在于，当所述控制单元控制所述发射单元在与所判断的回波信号相对应的第一脉冲的发射方向上不发射所述第二脉冲时，所述控制单元控制所述发射单元在偏离与所判断的回波信号相对应的第一脉冲的发射方向预定角度范围内的方向上也不发射所述第二脉冲。
  10. 根据权利要求9所述的系统，其特征在于，所述第一脉冲为第一单脉冲或第一脉冲序列，所述第二脉冲为第二单脉冲或第二脉冲序列。
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