WO2022213659A1 - 激光雷达及测距方法 - Google Patents

激光雷达及测距方法 Download PDF

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Publication number
WO2022213659A1
WO2022213659A1 PCT/CN2021/138331 CN2021138331W WO2022213659A1 WO 2022213659 A1 WO2022213659 A1 WO 2022213659A1 CN 2021138331 W CN2021138331 W CN 2021138331W WO 2022213659 A1 WO2022213659 A1 WO 2022213659A1
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Prior art keywords
laser
random number
time
signal
emitting
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PCT/CN2021/138331
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English (en)
French (fr)
Inventor
杨晋
顾天长
王重阳
向少卿
Original Assignee
上海禾赛科技有限公司
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Priority claimed from CN202110373632.2A external-priority patent/CN115166760A/zh
Priority claimed from CN202120703678.1U external-priority patent/CN214795206U/zh
Application filed by 上海禾赛科技有限公司 filed Critical 上海禾赛科技有限公司
Priority to DE112021007466.0T priority Critical patent/DE112021007466T5/de
Priority to JP2023562185A priority patent/JP2024513258A/ja
Priority to MX2023011405A priority patent/MX2023011405A/es
Priority to EP21935875.1A priority patent/EP4321904A4/en
Priority to KR1020237037010A priority patent/KR20240004373A/ko
Publication of WO2022213659A1 publication Critical patent/WO2022213659A1/zh
Priority to US18/482,307 priority patent/US20240036202A1/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
    • G01S17/06—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
    • 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
    • G01S17/46—Indirect determination of position data
    • G01S17/48—Active triangulation systems, i.e. using the transmission and 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
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • 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
    • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
    • G01S7/4815—Constructional features, e.g. arrangements of optical elements of transmitters alone using multiple 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
    • G01S7/484—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
    • G01S7/4865—Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak
    • 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

Definitions

  • the present disclosure relates to the field of photoelectric detection, and in particular, to a laser radar and a ranging method.
  • interference points are always a problem that needs to be overcome as much as possible.
  • Crosstalk between different lidars is one of the important reasons. Especially when lidars are widely used in the navigation of autonomous vehicles, the problem of crosstalk between lidars is particularly prominent.
  • the detection light of lidar is concentrated in several commonly used wavelengths, and it is easy to receive lasers or echoes of the same wavelength from other radars, which cannot be filtered out by means of filtering.
  • lidar Since the ranging principle of lidar is based on the measurement of the time of flight (tof) of the emitted laser pulse, if each lidar cannot determine whether the received laser pulse is from its own lidar, it will receive other When the laser radar emits pulses or echoes, it may be judged as the echo signal of the laser radar, resulting in interference points or even wrong test results.
  • the present invention designs a laser radar, which adopts the scheme of random light emission, so that the interference points that interfere with the laser radar do not have spatial correlation.
  • the timing and amplitude are modulated to determine whether the echo code is the same as the transmitted pulse sequence code, identify the echo signal, and further improve the anti-interference effect.
  • the control device is configured to generate a trigger signal based on a timing random number
  • the detection device configured to receive an echo signal of the laser pulse signal reflected by the target, and to convert the echo signal into an electrical signal
  • the data processing device determines the distance information of the target based on the time of transmitting the laser pulse signal and the time of receiving the echo signal.
  • a random number generator configured to generate the sequential random number
  • the control device being coupled to the random number generator to receive the sequential random number
  • the data processing device is configured to calculate the correlation of a plurality of distance information, and filter the distance information whose correlation is lower than a preset value as an interference signal.
  • the control device is configured to: select one light-emitting moment from the plurality of preset light-emitting moments according to the timing random number, as the triggering moment of the driving signal.
  • the control device is configured to: delay or advance the preset light-emitting time according to the timing random number, as the driving The trigger moment of the signal.
  • the laser emitting device includes a plurality of lasers and a plurality of drivers with the same number
  • the lidar includes a plurality of random number generators with the same number as the lasers.
  • the laser emitting device includes a plurality of lasers and a plurality of drivers coupled to the lasers one by one
  • the control device is coupled to the plurality of drivers
  • the timing random number corresponds to The firing sequence of multiple lasers.
  • the laser emitting device includes multiple groups of lasers
  • each group of lasers includes multiple lasers and multiple drivers coupled to the lasers one by one
  • the lidar further includes multiple groups of lasers.
  • control device is further configured to control the driver to drive the laser to emit a laser pulse sequence with multi-pulse encoding, the multi-pulse encoding including timing encoding, amplitude encoding and/or pulse width encoding .
  • the random number generator is a pseudo-random number generator
  • the time series random number is generated by one or more of the following methods:
  • S104 Determine the distance information of the target based on the time of transmitting the laser pulse signal and the time of receiving the echo signal.
  • the step S102 includes: based on the timing random number, controlling the emission time for the laser to emit the laser pulse signal, and/or controlling the time interval between adjacent laser pulses.
  • the step S102 includes: controlling the light-emitting sequence of the plurality of lasers based on the time-series random number.
  • step S102 includes generating a time series random number in the following manner:
  • the present invention also provides a laser radar, comprising: a laser emission device, a control device, a detection device and a data processing device, wherein,
  • the control device is configured to generate a trigger signal based on a timing random number
  • the laser emitting device includes at least one laser and a driver coupled to the laser, the driver is configured to drive the laser to emit a laser pulse signal according to the trigger signal;
  • the detection device configured to receive an echo signal of the laser pulse signal reflected by the target, and to convert the echo signal into an electrical signal
  • the data processing device determines the distance information of the target based on the time of transmitting the laser pulse signal and the time of receiving the echo signal,
  • the laser pulse signal is a laser pulse sequence with multi-pulse encoding, and the multi-pulse encoding includes timing encoding, amplitude encoding and/or pulse width encoding.
  • the laser randomly emits light, so that the interference points that interfere with the lidar have no spatial correlation, so that they can be judged as isolated points and filtered out, reducing the interference points. Furthermore, combined with the multi-pulse coding, the timing interval and amplitude between the multi-pulses are modulated, and the echo signal is identified by judging whether the echo coding is the same as the transmitted pulse sequence coding, and the anti-interference effect is further improved.
  • Fig. 1a shows a schematic diagram of the three-dimensional effect of non-random light-emitting information points
  • Fig. 1b shows a schematic diagram of the two-dimensional effect of non-random light-emitting information dots
  • FIG. 2 shows a diagram of a lidar module according to an embodiment of the present invention
  • Figure 3a shows a schematic diagram of the three-dimensional effect of randomly emitting information dots
  • Figure 3b shows a schematic diagram of the two-dimensional effect of randomly emitting information dots
  • FIG. 4 shows a timing diagram of random lighting timing in Embodiment 1 of the present invention
  • Fig. 5 shows the timing diagram of the random light-emitting delay according to the second embodiment of the present invention
  • Fig. 6b shows a schematic diagram of interference with random lighting sequence according to Embodiment 3 of the present invention
  • Figure 7 shows a schematic diagram of a plurality of laser arrangements
  • FIG. 8 shows a diagram of a lidar module according to Embodiment 4 of the present invention.
  • FIG. 9 shows a diagram of a lidar module according to Embodiment 5 of the present invention.
  • FIG. 10 shows a diagram of a lidar module according to Embodiment 6 of the present invention.
  • FIG. 11 shows a sequence diagram of random combination of multi-pulse coding at light-emitting moment according to Embodiment 7 of the present invention
  • FIG. 12 shows a timing diagram of the random combination of light-emitting delay and multi-pulse coding according to Embodiment 8 of the present invention
  • Fig. 13 shows a kind of multi-pulse coding driver structure schematic diagram
  • Figure 14 shows a timing diagram of a multi-pulse coded switch control signal and a switch trigger signal
  • Fig. 15 shows another kind of multi-pulse coding driver structure schematic diagram
  • 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.
  • Multi-line LiDAR includes multiple lasers and multiple detectors, and multiple lasers can be arranged in a specified direction (such as the vertical direction of the LiDAR); there is a corresponding relationship between the detectors and the lasers.
  • the corresponding detector receives the optical signal.
  • the time of the corresponding laser emitting the detection light and the time when the detector receives the signal can be used to calculate the time of flight of the light, and then obtain the distance information of the target object. After one transmission and reception is completed, the next laser emits detection light.
  • the lidar rotates along the axis at a certain speed during the working process.
  • data collection is performed after each rotation at a certain angle, so as to collect information around the radar during the rotation process to realize the perception of the surrounding environment.
  • all the data points obtained after the radar rotates once form a frame of point cloud.
  • multiple detectors are arranged in the vertical direction of the radar, and different detectors are used to receive echo signals at different vertical angles, so the data points measured by different detectors can be determined according to the position of the detector. Know its corresponding vertical angle.
  • the radar can rotate 360° in the horizontal direction.
  • the radar When the radar rotates to a certain horizontal angle, multiple lasers will send out detection light in turn, and the detector will detect the light signal after the corresponding laser emits the detection light. After all the detectors complete the patrol, the detection information corresponding to the vertical field of view (FOV) of the radar at the horizontal angle is obtained. After completing the detection at one horizontal angle, the radar has rotated to another horizontal angle for another round-robin detection. Therefore, the horizontal angle difference corresponding to two adjacent signal detections of the same detector can be expressed as the horizontal angle resolution of the radar.
  • FOV vertical field of view
  • the optical signal received by the detector not only includes the echo signal of the detection light reflected by the target, but may also contain interference signals, especially the detection light or reflected light emitted by other lidars, forming interference points.
  • Interference points can be simply divided into two types: a single noise point (which can also be considered an isolated point) and multiple or even continuous multiple noise points.
  • the filtering method of interference points is based on the fact that the interference generated by the signals of other lidars or other interference sources is random and accidental, that is, it is a spatial isolated point on the point cloud, and by judging the correlation between the data point and other adjacent data points , outliers can be identified and filtered out, thereby reducing interference points.
  • Figures 1a and 1b respectively show the three-dimensional and two-dimensional effect diagrams of the non-randomly emitting information points, which illustrate the data points obtained by lidar detecting two flat-shaped targets separated by a certain distance, the Y axis in Figure 1a Corresponding to the detection horizontal angle of the lidar, the Z axis corresponds to the detection vertical angle of the lidar, and the X axis corresponds to the target distance obtained by detection.
  • the radar can obtain the real-time detection angle and target distance information of the laser and the corresponding detector. 3D point cloud shown.
  • Figure 1b is an X-Y two-dimensional graph of Figure 1a.
  • the above-mentioned non-random light emission refers to that multiple lasers of the lidar emit detection light at predetermined time intervals in sequence, and the light emission time intervals of two adjacent lasers are usually equal.
  • the distance between the lidar and the target remains unchanged.
  • Multiple data points measured by multiple detectors at multiple horizontal angles correspond to the same distance value, which is a regularly arranged lattice on the point cloud.
  • the hollow circles represent the data points measured by the real echoes of the probe light reflected by the target (real points are shown), and the star-shaped points represent the interference points.
  • the laser of the radar emits a detection beam, and the detector is activated to receive the echo signal within a certain period of time.
  • the certain time can be determined by the predetermined detection distance of the lidar. For example, the farthest detection distance of the lidar is 200m. Start timing when the laser emits a detection beam and activate the detector. At the time of (200m ⁇ 2/light speed) (that is, the detection light flies After reaching the 200m target and being reflected and the echo signal reaching the lidar), the detector is deactivated to end the detection.
  • the system determines that the detection beam is an echo reflected by the target, and the flight time obtained by subtracting the detection light emission time from the echo reception time is used for Calculate the target distance. If an interference signal exceeding the noise threshold is received within the activation time of the detector, a target distance, namely the interference point, will also be calculated according to the reception time of the interference signal.
  • the interference signal is received within the activation time of the first detector, and an interference signal is generated in the first detection. point.
  • the interference signal caused by the next detection light of the interference radar is also easily received within the activation time of the second detector, and an interference point is also generated during the detection of the second detector.
  • the third and fourth detectors adjacent to the first and second detectors may receive interference signals caused by the detection light emitted by the interfering radars in turn. There are interference points in all of them. The distance corresponding to multiple interference points is related to the time interval of the detection light emitted by the interference radar.
  • the emission time interval of the multiple lasers of this lidar is fixed, and the time interval of the multiple lasers of the interference radar is also fixed, then
  • the receiving time of the interference signal is regular, and the distance of the target object calculated from it also has a certain regularity, which makes the interference point have spatial correlation.
  • the radar at a certain horizontal angle corresponding to the same Y-axis coordinate
  • the five detectors shown in the figure have received interference signals, resulting in continuous interference points corresponding to the same horizontal and vertical angles.
  • These interference points correspond to The difference between the distance information is small, and they have a strong spatial correlation with each other.
  • the spatial isolated point discrimination method cannot be used to identify them, resulting in noise in the point cloud.
  • the present invention designs a laser radar, which adopts a random lighting scheme to reduce the spatial correlation of the interference points that interfere with the laser radar to the extent that the algorithm can identify them, and then filter them out as interference signals.
  • the random light-emitting of the present invention includes multiple ways: the emission timing of the detection beam emitted by each laser is randomly jittered; the light-emitting order of the laser is randomly selected among the plurality of lasers, that is, the light is not emitted sequentially from the first to the Nth according to the installation order, Instead, randomly select a laser among the N lasers to emit light, and next time randomly select a laser among the remaining N-1 lasers to emit light, or set a random order for the N lasers, and make the corresponding lasers in turn according to the random order.
  • N is a positive integer, indicating the number of adjacently installed lasers
  • a probe beam emitted by each laser includes multiple pulses, and the probe beams emitted by different lasers contain random time between multiple pulses interval; a combination of two or more of the above random ways.
  • the technical effect of the random lighting scheme of the present invention is analyzed. It is assumed that multiple detectors of this lidar receive the same number of jamming signals, because the emission of jamming radar is regular, compared with non-random light emission, the actual receiving time of jamming signals remains unchanged, but the detection beam of this lidar emits With randomness, so that two adjacent detectors will not receive interference signals at the same time, the horizontal angle and/or vertical angle corresponding to the generated multiple interference points are not adjacent, and the spatial distance of the interference points becomes larger; The two adjacent detectors still receive interference signals at the same time.
  • the detection angle of the interference point and/or the distance corresponding to the interference point in the point cloud also generate randomness, which reduces the spatial correlation of the interference point and exposes it, so that the spatial isolated point discrimination algorithm can identify it, and then filter out.
  • the present invention provides a laser radar 10 , as shown in FIG. 2 , including a laser emission device 11 , a control device 12 , a detection device 13 and a data processing device 14 .
  • the laser emitting device 11 includes a laser 111 and a driver 112 coupled thereto, and is configured to emit a laser pulse signal.
  • the laser emitting device 11 includes at least one laser 111 and a driver 112 corresponding to it.
  • FIG. 2 a schematic diagram of an embodiment in which the laser emitting device 11 includes a laser 111 , a driver 112 and a random number generator 15 is shown.
  • the laser emitting device 11 includes a plurality of lasers 111 , a plurality of drivers 112 and a plurality of random number generators 15 will be described in detail below.
  • the laser 111 may be, for example, a laser diode (laser diode, LD), an edge-emitting laser (EEL), or a vertical-cavity surface-emitting laser (VCSEL).
  • the driver 112 may include, for example, switches and voltage sources or energy storage devices.
  • the control device sends a trigger signal to the switch to turn on the switch, and the voltage source or the energy storage device discharges the laser, thereby driving the laser to emit laser pulses.
  • the control device 12 is coupled to the driver 112 , and is configured to generate a trigger signal based on a random number in time sequence.
  • the driver 112 receives the trigger signal from the control device 12 and drives the coupled laser 111 to emit a laser pulse signal L.
  • the timing random number can be a random integer or a random floating point number, and can correspond to a number or time value in the time domain.
  • the control device 12 generates a trigger signal according to the timing random number and controls the laser 111 to emit light randomly through the driver 112 to reduce interference. For each laser emitting device 11 , it may have one or more preset emitting times. In the present invention, the control device 12 randomly adjusts or selects the emitting time of the laser emitting device 11 according to the timing random number.
  • the laser pulse signal L is diffusely reflected on the target, and part of the echo signal L' returns to the lidar 10.
  • the detection device 13 is configured to receive the echo signal L' of the laser pulse signal L reflected by the target, and convert all the echo signals L'.
  • the echo signal L' is converted into an electrical signal.
  • the detection device 13 may include, for example, an avalanche photodiode (APD), a single photon avalanche diode (SPAD), or other types of photodetectors, which can convert echo signals into current signals and voltage signals. , or a digital signal.
  • the data processing device 14 is configured to determine the distance information of the target based on the time at which the laser pulse signal L is emitted and the time at which the echo signal L' is received.
  • the data processing device 14 is, for example, coupled to the detection device 13, so that the reception time of the echo can be calculated from the electrical signal.
  • the data processing device 14 is coupled to the control device 12, so that the trigger time of the trigger signal can be obtained as the emission time of the laser pulse signal. Additionally or alternatively, the data processing device 14 can be coupled with the laser emitting device 11, so as to obtain a more accurate laser pulse signal emission time, which are all within the protection scope of the present invention.
  • the data processing device 14 may include one or more of an analog-to-digital converter ADC, a time-to-digital converter TDC, a microprocessor.
  • the hollow circles above represent the data points measured by the real echoes of the probe light reflected by the target (real points shown in the figure), and the star-shaped points represent the interference points.
  • the lidar does not move, the distance to the target remains unchanged.
  • Multiple data points measured by multiple detectors at multiple horizontal angles correspond to the same distance value.
  • the point cloud is a regularly arranged lattice, as shown in the figure As shown in the real point in the middle; combined with Figure 3b, the lidar at a certain horizontal angle (corresponding to the same Y-axis coordinate), multiple detectors have received interference signals, because other lidars do not use the same random lighting strategy, making interference
  • the distance values obtained by point calculation form divergent interference points in the horizontal and vertical angles.
  • the lidar 10 further includes a random number generator 15 configured to generate sequential random numbers, and the control device 12 is coupled to the random number generator 15 to receive the random number generator 15. Timing random numbers.
  • FIG. 4 shows a timing chart of random lighting timing according to Embodiment 1 of the present invention.
  • the control device 12 may store a plurality of light-emitting moments in advance, such as a plurality of preset light-emitting moments t1, t2, . . . , tn as shown in FIG.
  • the generator 15 receives the timing random number, it selects a lighting timing tx from the plurality of preset lighting timings t1, t2, ..., tn according to the timing random number as the lighting timing of the laser, and the control device 12 emits light.
  • a trigger signal is sent out, and the driver 112 receives the trigger signal and drives the laser 111 coupled thereto to send out a laser pulse signal.
  • the laser 111 the moment when a single laser pulse is emitted is random, and the interference source (other lidars), because the emission time of the laser pulse is a certain time value, when the detection device 13 receives two pulse signals, it can be It is easy to identify the interference point generated by the interference signal, so as to reduce the interference.
  • the time series random number is an integer between 1 and n.
  • the time series random number output by the random number generator 15 is a specific time value.
  • the random number generator 15 is configured to generate a random floating point number between 0 and tmax as the timing random number.
  • the control device 12 After receiving the random floating point number, the control device 12 sends a trigger signal at the time corresponding to the random floating point number to drive the laser 111 to emit a laser pulse signal.
  • tmax is determined according to the longest time interval during which a laser emits light/detector is activated to receive a corresponding detection. For example, the flight time corresponding to the longest detection distance of 200m is 1.33 ⁇ s. Assuming that the time interval allocated between two adjacent detections is 1.5 ⁇ s, tmax does not exceed 0.17 ⁇ s to ensure the normal progress of the next detection.
  • the time interval between two adjacent detections can be allocated according to the frame rate, rotation speed, line count or resolution of the lidar.
  • FIG. 5 shows a timing diagram of random emission delay in Embodiment 2 of the present invention.
  • each laser detection pulse emission has a preset emission time.
  • the random number generator 15 generates a random light-emitting delay ⁇
  • the control device 12 uses ⁇ as the delay of the light-emitting time of the laser, thereby changing the actual light-emitting time of the laser.
  • each time the laser performs a time-of-flight measurement for example, two probe pulses are emitted.
  • the delay time ⁇ 1 shown in the figure is a negative value, so the light-emitting time t1 is actually advance; similarly, the control device 12 delays the lighting time t1' according to the random lighting delay ⁇ 1' generated by the random number generator 15.
  • the delay ⁇ 1' shown in the figure is a positive value, so in fact The light-emitting time t1' is delayed.
  • the emission timings of the two detection pulses are advanced and delayed respectively.
  • the delay of multiple detection pulses in one time-of-flight measurement of the same laser may also be are the same, that is, have the same sign, and have the same absolute value.
  • control device 12 may also pre-store n different delay amounts ⁇ 1, ⁇ 2, . x and output it to the control device, the control device selects the delay amount ⁇ x according to the random integer x, adds the delay ⁇ 1 at the preset light-emitting time and sends out a trigger signal, the corresponding driver 112 receives the trigger signal, and drives the laser 111-1 to emit laser light
  • the pulse signal is used to realize the randomness of the light-emitting moment through the random light-emitting delay scheme.
  • the laser emitting device 11 includes a plurality of lasers 111, laser 111-1, laser 111-2, laser 111-3 . . . laser 111-n, wherein each laser 111 has a preset emitting time.
  • the random number generator 15 generates a random light-emitting delay time ⁇ or a random integer x, and the control device 12 determines the light-emitting time delay of each laser 111 accordingly.
  • the control device 12 sends a trigger signal after adding a delay ⁇ 1 at the preset luminous time, and the corresponding driver 112 receives the trigger signal, and drives the laser 111-1 coupled to it to emit a laser pulse signal;
  • the control device 12 sends a trigger signal after adding the delay ⁇ 2 at the preset lighting time, and the corresponding driver 112 receives the trigger signal and drives the coupled laser 111-2 to emit a laser pulse signal;
  • the control device 12 sends a trigger signal after adding a delay ⁇ 3 at the preset light-emitting time, and the corresponding driver 112 receives the trigger signal and drives the coupled laser 111-3 to emit a laser pulse signal; and so on.
  • the solid line pulse is the preset light-emitting time, and a delay ⁇ is added to the preset light-emitting time, so that the actual light-emitting time of each laser is random.
  • the value of ⁇ can be a positive value or a negative value.
  • a positive value indicates that the actual light-emitting time is delayed from the preset light-emitting time, as shown in the first laser pulse of the laser 111-3 and the laser 111-n in FIG.
  • the dotted line pulse indicates The actual light-emitting time is later than the preset light-emitting time indicated by the solid line pulse; the negative value indicates that the actual light-emitting time is earlier than the preset light-emitting time, such as the first laser pulse of laser 111-1 and laser 111-2 in Fig.
  • the actual light-emitting time indicated by the pulse is earlier than the preset light-emitting time indicated by the solid line pulse.
  • the delay ⁇ reduces the spatial correlation of the interference points, and it can be expected that the larger the value (absolute value) of the delay ⁇ , the lower the spatial correlation of the interference points.
  • the distance between each point in the point cloud and the adjacent points or the average value of the distance between each point and multiple adjacent points can be calculated, and the correlation distance threshold is set. If the distance from the adjacent point is greater than the threshold, the point is judged to be an interference point and filtered out. Therefore, the correlation distance threshold should be greater than the distance of the real data points and less than the possible distance of the interference points. Within the possible value range of the delay ⁇ , the larger the value of ⁇ , the greater the spatial distance of the interference points, and the corresponding correlation The distance threshold can be increased accordingly.
  • the control device 12 can not only adjust the emission timing of each detection pulse according to the random number of the time series, but also directly adjust the time interval between double pulses in a detection beam, which will not be repeated here.
  • control device 12 adjusts the light-emitting sequence of the plurality of lasers according to the time sequence random number. This is described in detail below with reference to FIG. 6 .
  • Fig. 6b shows a schematic diagram of random light-emitting sequence interference according to Embodiment 3 of the present invention.
  • the multiple lasers 111 in the same column emit light in the order of 3-5-1-2-4, and The corresponding detectors are received in the order of 3-5-1-2-4.
  • the detection light emitted in the order of a-b-c-d-e, or the reflected light generated by a certain target, as shown in Fig. 6b may be received by the detector 131 in a different order, and the detector 131 There is no spatial correlation between the measured interference points and can be easily filtered out.
  • the light-emitting sequence is random, that is, the light-emitting sequence of multiple lasers is random, which is equivalent to applying a larger delay to the light-emitting moment.
  • the interference source emits light in the order of 1-2-3-4-5
  • the laser radar emits light in the order of 3-5-1-2-4. Even if interference signals are received on each detector, the laser radar will emit light in the order of 3-5-1-2-4
  • the 5th detector receives the interference signal generated by the second emission of the interference source
  • the fourth detector receives the interference signal generated by the fifth emission of the interference source.
  • the distances corresponding to the two interference points caused by the adjacent fourth detector and the fifth detector receiving the interference signal are also very different, so they are easily exposed as spatial lone points.
  • the random lighting scheme includes four types: random lighting time, random lighting delay, random lighting sequence and random lighting interval.
  • the four schemes can be used in combination.
  • the combination of random lighting sequence and random lighting time can further reduce the Spatial correlation of each interference point.
  • FIG. 7 shows a schematic diagram of the arrangement of multiple lasers.
  • the laser emitting device 11 includes multiple lasers 111. As shown by the circles in FIG. 7, the multiple lasers 111 are fixed on one or more circuit boards, and the circuit boards pass through the multiple lasers 111. The distribution of different line densities is obtained by the number of lasers installed on the board and the mounting position of the circuit board.
  • the above-mentioned random lighting scheme of the present invention can be controlled independently for each column of lasers; all lasers can also be taken as a whole, and the lighting time of each laser is random relative to other lasers.
  • FIG. 8 shows a diagram of a lidar module according to Embodiment 4 of the present invention.
  • the laser emitting device 11 includes a plurality of lasers 111-1, 111-2, . 112-1, 112-2, . . . , 112-n, in addition, the lidar 10 includes random number generators 15-1, 15-2, .
  • the control device 12 In the ranging state of the lidar 10 , the control device 12 generates a trigger signal based on the time sequence random number generated by a random number generator 15 , and the corresponding driver 112 drives the coupled laser 111 to emit laser pulse signals according to the trigger signal, and sequentially
  • each random number generator 15 corresponds to one driver and one laser, which can realize random light-emitting time, random light-emitting delay and random light-emitting interval.
  • the control device 12 can also control the sequence of multiple trigger signals based on multiple timing random numbers, and then drive the coupled lasers 111 to emit light in random order through the corresponding driver 112, which can realize the scheme of random lighting order. To further reduce interference, multiple random lighting schemes can be used in combination.
  • FIG. 9 shows a diagram of a lidar module according to Embodiment 5 of the present invention.
  • the laser emitting device 11 includes a plurality of lasers 111-1, 111-2, . 112-1, 112-2, . . . , 112-n, in addition, the lidar 10 includes a random number generator 15 .
  • the control device 12 In the ranging state of the lidar 10, the control device 12 generates a plurality of trigger signals based on a plurality of time series random numbers generated by the random number generator 15, and the plurality of drivers 112 drive the coupled lasers 111 to emit laser pulse signals according to the corresponding trigger signals , any one of the four schemes of random lighting time, random lighting delay, random lighting interval and random lighting sequence or a combination of them can be realized.
  • FIG. 10 shows a diagram of a lidar module according to Embodiment 6 of the present invention.
  • the laser emitting device 11 includes a plurality of lasers 111 and drivers 112 that are the same in number as the lasers 111 and are coupled in one-to-one correspondence. Grouping, for example, according to a column of lasers 111 and corresponding drivers 112 as shown in FIG. 7 into a group (the dotted box in FIG. 7 is a group), as shown in FIG. 10 , the first group, ..., the first group In n groups, the correlation of the information points measured by the lasers 111 in each group is relatively high, so the lasers in each group can be independently controlled.
  • the lidar 10 includes a plurality of random number generators 15 corresponding to the number of groups, and the random number generated by each random number generator 15 corresponds to a group of lasers 111 and drivers 112, which can realize random lighting time, random lighting delay, Any one of the four schemes of random lighting interval and random lighting sequence or a scheme combined with each other.
  • the scheme of random light emission is introduced above through 6 preferred embodiments, so that the interference points that interfere with the lidar do not have spatial correlation, so that the interference signals can be easily distinguished and filtered out.
  • the random lighting scheme can also be combined with the multi-pulse coding scheme, and the echo signal can be identified by judging whether the coding of the echo signal is the same as that of the transmitted pulse sequence.
  • control device 12 is further configured to control the driver 112 to drive the coupled laser 111 to emit a laser pulse sequence with multi-pulse coding, the multi-pulse coding including timing coding, amplitude coding and/or pulse width coding.
  • the two pulse emission times t21, t22 of the laser 111-2...the two pulse emission times tn1 and tn2 of the laser 111-n are random numbers, then the timing interval of the double pulses t12-t11 ⁇ t22-t21 ⁇ t32-t31 ⁇ ... ⁇ tn2-tn1.
  • the laser pulse sequence includes multiple laser pulses, such as the first pulse, the second pulse, ..., the Nth pulse, and the emitting timings of the multiple laser pulses are all based on timing random numbers, so that the leading edges of multiple pulses are The time interval is random.
  • a scheme in which the light emission interval is random can be used to directly set the timing intervals of multiple pulses, which can achieve the same random effect.
  • the difference from using the random lighting moment scheme alone is that the data processing device 14 can identify the echo signal according to the time sequence code.
  • FIG. 12 shows a timing diagram of random light-emitting delay combined with multi-pulse coding according to the eighth embodiment of the present invention.
  • a fixed light-emitting interval plus random event jitter is adopted.
  • each laser 111 is set with a fixed two At the light-emitting moment of each pulse, a random delay ⁇ is added to the two light-emitting moments, so that the pulse front of the first pulse is random, that is, the light-emitting moment is randomized; the interval between the front edge of the second pulse and the first pulse is also It has randomness, that is, pulse timing interval coding.
  • This is another implementation scheme of time sequence coding of multi-pulse coding, and the data processing device 14 can identify the echo signal according to the time sequence coding.
  • the above code is a laser pulse sequence with intervals in time sequence, which can be called time sequence code.
  • it can also be a pulse sequence that is pulse intensity modulated in time sequence, which can be called amplitude coding, or a combination of two coding methods, that is, a pulse sequence that has an interval in time sequence and is pulse intensity modulated.
  • the pulse width can also be changed based on timing random numbers to realize pulse width encoding.
  • Amplitude encoding and pulse width encoding in multi-pulse encoding are mainly implemented based on drivers, which are further described below.
  • FIG. 13 shows a schematic diagram of the structure of a multi-pulse coded driver.
  • the driver includes a plurality of charging units and an energy storage device.
  • the switch trigger signal (TRIGGER) controls the switch to be off
  • the charging unit is in the switch control signal (GATE1, GATE2, ..., GATEN)
  • the energy storage device is charged in sequence.
  • the switch trigger signal (TRIGGER) controls the switch to close, and the energy storage device starts to discharge, so that the laser emits laser pulses.
  • FIG 14 shows a timing diagram of a multi-pulse coded control signal and a switch trigger signal
  • the switch trigger signal (TRIGGER) is triggered when the switch control signals (GATE1, GATE2, ..., GATEN) end, such as shown in Figure 14
  • the falling edge of the switch control signal (GATE1, GATE2,..., GATEN) triggers the falling edge of the switch trigger signal (TRIGGER); if the end of the switch trigger signal (TRIGGER) is the rising edge of the timing signal, the rising edge is used as the switch control
  • the trigger timing of the signal ensures that the emission process starts after the charging is completed, and the next charging-emitting process can be started immediately after the previous charging and lighting process is completed.
  • the time widths of the switch control signals (GATE1, GATE2, .
  • control over the intensity of the transmitted pulse can be achieved.
  • the switch control signal GATE1 and the switch control signal GATE2 have different signal durations, the amount of electricity charged in the energy storage device is also different, and thus the intensity of a single pulse transmitted is also different.
  • different switch control signal durations it is possible to control the transmission pulse width, thereby realizing the distinction of echo signals and avoiding interference between different transmission signal sequences.
  • FIG. 15 shows a schematic structural diagram of another multi-pulse coding driver.
  • Multiple energy storage devices are connected to the power supply, and each energy storage device is connected to a control switch.
  • the control switch is responsible for controlling the on-off of the energy storage device and the laser. When the control switch between a certain energy storage device and the laser is closed, the electric charge stored in the energy storage device drives the laser to emit laser pulses.
  • Each unit in FIG. 15 is independent of each other, and the control switches are independently controlled by the control units.
  • the control unit can control the control switches to open or close independently.
  • the energy of the emitted laser pulse is the sum of the energy of several energy storage devices.
  • the detection of distant objects can be achieved.
  • the pulse shape emitted in time sequence can be controlled.
  • the intensity of the pulse transmitted at that moment is 1 unit
  • the intensity of the pulse transmitted at the corresponding moment is N units.
  • the coding of the timing, amplitude and pulse width of the laser pulse can be realized by controlling the driver.
  • the echo code is the same as the code of the transmitted laser pulse sequence, the echo signal is identified, and the anti-interference effect is further improved.
  • the present invention also provides a ranging method 100, as shown in FIG. 16, the method includes:
  • step S101 generating a time series random number
  • At step S102 controlling at least one driver of the laser emitting device to drive the coupled lasers to emit laser pulse signals based on the timing random number;
  • step S104 Determine the distance information of the target based on the time of transmitting the laser pulse signal and the time of receiving the echo signal.
  • the method further includes: calculating the correlation of a plurality of distance information, and determining the distance information whose correlation is lower than a preset value as an interference signal.
  • the step S102 includes: based on the timing random number, controlling the emission time for the laser to emit the laser pulse signal, and/or controlling the time interval between adjacent laser pulses.
  • the step S102 includes: controlling the light-emitting sequence of the plurality of lasers based on the time-series random number.
  • step S102 includes generating a time series random number in the following manner:
  • the control device 22 is configured to generate a trigger signal based on a time sequence random number
  • the detection device 23 is configured to receive an echo signal of the laser pulse signal reflected by the target object, and convert the echo signal into an electrical signal;
  • the laser pulse signal is a laser pulse sequence with multi-pulse encoding, and the multi-pulse encoding includes timing encoding, amplitude encoding and/or pulse width encoding.

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Abstract

一种激光雷达和测距方法，激光雷达包括：激光发射装置（11）、控制装置（12）、探测装置（13）以及数据处理装置（14），其中，控制装置（12）配置成可基于时序随机数产生触发信号；激光发射装置（11）包括至少一个激光器（111）和与激光器（111）耦接的驱动器（112），驱动器（112）配置成根据触发信号驱动激光器（111）发射激光脉冲信号；探测装置（13），配置为接收激光脉冲信号被目标物反射的回波信号，并将回波信号转换为电信号；和数据处理装置（14），基于发射激光脉冲信号的时间和接收回波信号的时间，确定目标物的距离信息。激光雷达采用随机发光的方案，使得干扰激光雷达的干扰点不具有空间相关性，再结合多脉冲编码，对多脉冲之间的时序和幅度进行调制，判断回波编码是否与发射脉冲序列编码相同，识别回波信号，进一步提高抗干扰效果。

Description

激光雷达及测距方法 技术领域
本公开涉及光电探测领域，尤其涉及一种激光雷达以及一种测距方法。
背景技术
激光雷达的产生的点云中，干扰点始终是一个需要尽量克服的问题。干扰点产生的原因很多，不同激光雷达间的串扰产生干扰点是其中一个重要原因，特别是当激光雷达被广泛应用于自动驾驶车辆的导航，激光雷达间的串扰问题尤为突出。激光雷达的探测光集中在常用的几种波长，很容易收到其它雷达发出的相同波长的激光或回波，无法通过滤光等手段滤除。由于激光雷达的测距原理是基于对发射激光脉冲的飞行时间(time of flight，tof)进行测量，如果每台激光雷达无法判定收到的激光脉冲是不是本激光雷达发出的，那么接收到其他激光雷达发出的脉冲或回波时，可能会判定为本激光雷达的回波信号，产生干扰点甚至测试结果出错。
背景技术部分的内容仅仅是公开人所知晓的技术，并不当然代表本领域的现有技术。
发明内容
有鉴于现有技术的至少一个缺陷，本发明设计了一种激光雷达，采用随机发光的方案，使得干扰激光雷达的干扰点不具有空间相关性，再结合多脉冲编码，对多脉冲之间的时序和幅度进行调制，判断回波编码是否与发射脉冲序列编码相同，识别回波信号，进一步提高抗干扰效果。
本发明提供一种激光雷达，包括：激光发射装置、控制装置、探测装置以及数据处理装置，其中，
所述控制装置配置成可基于时序随机数产生触发信号；
所述激光发射装置包括至少一个激光器和与所述激光器耦接的驱动器， 所述驱动器配置成根据所述触发信号驱动所述激光器发射激光脉冲信号；
所述探测装置，配置为接收所述激光脉冲信号被目标物反射的回波信号，并将所述回波信号转换为电信号；和
所述数据处理装置，基于发射所述激光脉冲信号的时间和接收所述回波信号的时间，确定所述目标物的距离信息。
根据本发明的一个方面，还包括随机数发生器，配置为生成所述时序随机数，所述控制装置耦接到所述随机数发生器，以接收所述时序随机数。
根据本发明的一个方面，其中所述数据处理装置配置成可计算多个距离信息的相关性，并将相关性低于预设值的距离信息作为干扰信号滤除。
根据本发明的一个方面，其中所述激光器具有多个预设的发光时刻，所述控制装置配置成：根据所述时序随机数，从所述多个预设的发光时刻中选取一个发光时刻，作为所述驱动信号的触发时刻。
根据本发明的一个方面，其中所述激光器具有一个预设的发光时刻，所述控制装置配置成：根据所述时序随机数，对所述预设的发光时刻进行延迟或提前，作为所述驱动信号的触发时刻。
根据本发明的一个方面，其中所述激光器配置成可发射多个脉冲，所述控制装置配置成可根据所述时序随机数调整相邻的两个脉冲对应的触发信号之间的时间间隔。
根据本发明的一个方面，其中所述激光发射装置包括数目相同的多个激光器和多个驱动器，所述激光雷达包括与所述激光器数目相同的多个随机数发生器。
根据本发明的一个方面，其中所述激光发射装置包括多个激光器以及与所述激光器一一耦接的多个驱动器，所述控制装置与所述多个驱动器耦接，所述时序随机数对应多个激光器的发光顺序。
根据本发明的一个方面，其中所述激光发射装置包括多组激光器，每组激光器包括多个激光器及与所述激光器一一耦接的多个驱动器，所述激光雷达还包括与所述多组激光器对应的多个随机数发生器，每个随机数发生器产生的时序随机数和与其对应的一组激光器的发光顺序相对应。
根据本发明的一个方面，其中所述控制装置还配置成控制所述驱动器驱动所述激光器发射具有多脉冲编码的激光脉冲序列，所述多脉冲编码包括时序编码、幅度编码和/或脉冲宽度编码。
根据本发明的一个方面，其中所述随机数发生器为伪随机数发生器，通过以下方式中的一项或多项生成所述时序随机数：
从预存的随机数表格中随机抽取；
基于时钟相位生成；
基于系统温度生成；和
通过线性反馈移位寄存器生成。
本发明还提供一种测距方法，所述方法包括：
S101：生成时序随机数；
S102：基于所述时序随机数，控制激光发射装置的至少一个驱动器驱动相耦接的激光器发射激光脉冲信号；
S103：接收所述激光脉冲信号被目标物反射的回波信号；和
S104：基于所述激光脉冲信号发射时间和接收回波信号的时间，确定所述目标物的距离信息。
根据本发明的一个方面，还包括：计算多个距离信息的相关性，将相关性低于预设值的距离信息判断为干扰信号。
根据本发明的一个方面，其中所述步骤S102包括：基于所述时序随机数，控制激光器发射所述激光脉冲信号的发射时间，和/或控制相邻激光脉冲之间的时间间隔。
根据本发明的一个方面，其中所述步骤S102包括：基于所述时序随机数，控制多个激光器的发光顺序。
根据本发明的一个方面，其中所述步骤S102包括通过以下方式生成时序随机数：
从预存的随机数表格中随机抽取；
基于时钟相位生成；
基于系统温度生成；和
通过线性反馈移位寄存器生成。
本发明还提供一种激光雷达，包括：激光发射装置、控制装置、探测装置以及数据处理装置，其中，
所述控制装置配置成可基于时序随机数产生触发信号；
所述激光发射装置包括至少一个激光器和与所述激光器耦接的驱动器，所述驱动器配置成根据所述触发信号驱动所述激光器发射激光脉冲信号；
所述探测装置，配置为接收所述激光脉冲信号被目标物反射的回波信号，并将所述回波信号转换为电信号；和
所述数据处理装置，基于发射所述激光脉冲信号的时间和接收所述回波信号的时间，确定所述目标物的距离信息，
所述激光脉冲信号为具有多脉冲编码的激光脉冲序列，所述多脉冲编码包括时序编码、幅度编码和/或脉冲宽度编码。
通过激光器随机发光，使干扰激光雷达的干扰点不具有空间相关性，从而可被判定为孤点而滤除，减少干扰点。更进一步地，结合多脉冲编码，对多脉冲之间的时序间隔、幅度进行调制，通过判断回波编码是否与发射脉冲序列编码相同，识别回波信号，进一步提高抗干扰效果。
附图说明
构成本公开的一部分的附图用来提供对本公开的进一步理解，本公开的示意性实施例及其说明用于解释本公开，并不构成对本公开的不当限定。在附图中：
图1a示出了非随机发光的信息点三维效果示意图；
图1b示出了非随机发光的信息点二维效果示意图；
图2示出了本发明一个实施例的激光雷达模块图；
图3a示出了随机发光的信息点三维效果示意图；
图3b示出了随机发光的信息点二维效果示意图；
图4示出了本发明实施例一发光时刻随机的时序图；
图5示出了本发明实施例二发光延时随机的时序图；
图6a示出了激光器顺序发光时的干扰示意图；
图6b示出了本发明实施例三发光顺序随机的干扰示意图；
图7示出了多个激光器排布的示意图；
图8示出了本发明实施例四的激光雷达模块图；
图9示出了本发明实施例五的激光雷达模块图；
图10示出了本发明实施例六的激光雷达模块图；
图11示出了本发明实施例七的发光时刻随机结合多脉冲编码的时序图；
图12示出了本发明实施例八的发光延时随机结合多脉冲编码的时序图；
图13示出了一种多脉冲编码的驱动器结构示意图；
图14示出了一种多脉冲编码的开关控制信号与开关触发信号的时序图；
图15示出了另一种多脉冲编码的驱动器结构示意图；
图16示出了本发明一种测距方法的流程图；和
图17示出了本发明一个实施例的激光雷达模块图。
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。
多线激光雷达包括多个激光器和多个探测器，多个激光器可按照指定方向(如激光雷达的竖直方向)排布；探测器与激光器存在对应关系，一个激光器发出探测光后，与之对应的探测器接收光信号，当探测器接收到光信号后，通过对应的激光器发射探测光的时间与探测器接收到信号的时间，可以计算得到光飞行时间，进而得到目标物距离信息。一次发射与接收完成之后， 下一个激光器发出探测光。
激光雷达在工作过程中以一定转速沿轴线旋转，根据设定的采样频率，每次旋转一定角度后进行一次数据采集，从而在旋转过程中采集雷达周围的信息，以实现对周围环境的感知，并且，雷达旋转一周后得到的所有数据点形成一帧点云。以常规的机械旋转式雷达为例，多个探测器沿雷达的竖直方向排列，不同探测器用于接收不同竖直角度的回波信号，因而不同探测器测得的数据点可根据探测器位置获知其对应的竖直角度。雷达可以进行360°水平方向的旋转，在雷达旋转到某一水平角度时，多个激光器依次轮巡发出探测光，探测器在与其对应的激光器发出探测光之后对光信号进行探测。在所有探测器完成轮巡之后，获得了该水平角度下对应于雷达垂直视场角(Field of View，FOV)的探测信息。在完成一个水平角度下的探测后，雷达已经旋转至另一水平角度，进行再一次的轮巡探测。因而，同一个探测器相邻两次信号探测对应的水平角度差可以表示为雷达的水平角分辨率。
在实际探测中，探测器接收到的光信号不仅包括探测光被目标物反射的回波信号，也可能含有干扰信号，尤其是其他激光雷达发出的探测光或反射光，形成干扰点。干扰点可以简单地分为两种：单个噪点(也可以认为是孤点)和多个甚至是连续的多个噪点。通常干扰点的滤除方法是基于其他激光雷达或其他干扰源的信号产生的干扰是随机的、偶发的，即在点云上是空间孤点，通过判断数据点与其他相邻数据点的相关性，可以识别孤点并将其滤除，从而减少干扰点。
但是，当干扰点来自于其他激光雷达时，尤其是其他激光雷达也是多个激光器和探测器轮巡发光探测，本激光雷达的多个探测器可能都会收到干扰信号，在同一水平角度探测得到多个干扰点，造成这些干扰点存在一定的相关性，通过上述判断空间孤点的方法难以将其滤除，进而在点云上形成噪点。
图1a和图1b分别示出了非随机发光的信息点的三维和二维效果示意图，示意了激光雷达对相隔一定距离的两个平板形目标物进行探测获得的数据点，图1a中Y轴对应激光雷达的探测水平角度，Z轴对应激光雷达的探测垂直角度，X轴对应探测获得的目标物距离，雷达可以根据激光器和相对应探 测器的实时探测角度和目标物距离信息获得图1a所示的三维点云。图1b是图1a的X-Y二维图形。上述非随机发光，指的是激光雷达的多个激光器依次以预定的时间间隔发出探测光，且相邻两个激光器的发光时间间隔通常是相等的。在激光雷达不动的情况下，激光雷达与目标物的距离不变，多个探测器在多个水平角度测得的多个数据点对应同一距离值，在点云上是规则排列的点阵。如图1a所示，空心圆代表探测光被目标物反射的真实回波测得的数据点(图示真实点)，星形点代表干扰点。
从激光雷达的测距方式分析，雷达的激光器发出探测光束，在一定时间内激活探测器接收回波信号。该一定时间可由激光雷达的预定探测距离确定，例如激光雷达的最远探测距离为200m，以激光器发出探测光束开始计时并激活探测器，在(200m×2/光速)的时间(即探测光飞行到200m目标物并被反射、回波信号到达激光雷达)后将探测器去激活，结束该次探测。在上述探测器激活的时间内，一旦接收到超过噪声阈值的光信号，系统即判断为探测光束被目标物反射的回波，将回波接收时间减去探测光发射时间得到的飞行时间用于计算目标物距离。若在探测器激活时间内收到超过噪声阈值的干扰信号，也会根据该干扰信号的接收时间计算出一个目标物距离，即干扰点。
若存在一个干扰雷达，与本激光雷达用相似的规律和时间间隔发出探测光束，则在第一次探测时，第一探测器激活时间内收到干扰信号，在第一次探测中产生一个干扰点。第二次探测时，第二探测器激活时间内同样容易收到干扰雷达的下一次探测光造成的干扰信号，在第二探测器的探测中也产生一个干扰点。基于同样的原因，与第一、第二探测器相邻的第三、第四等多个探测器可能都会收到干扰雷达依次发出的探测光造成的干扰信号，在多个探测器的探测结果中均存在干扰点。多个干扰点对应的距离与干扰雷达发出探测光的时间间隔相关，若本激光雷达的多个激光器轮巡发光的发射时间间隔固定、干扰雷达多个激光器轮巡发光的时间间隔也固定，那么干扰信号的接收时间是规律的，由此计算出的目标物距离也具有一定的规律性，使干扰点具有空间相关性。
结合图1b，雷达在某一个水平角度(对应相同的Y轴坐标)，图示的5 个探测器都收到了干扰信号，产生对应相同的水平角度和垂直角度的连续干扰点，这些干扰点对应的距离信息相差较小，彼此具有较强的空间相关性，采用空间孤点判别方法就无法识别出来，在点云中产生噪点。
基于上述分析，本发明设计了一种激光雷达，采用随机发光的方案，使得干扰激光雷达的干扰点空间相关性降低，达到算法可以识别的程度，进而将其作为干扰信号滤除。
本发明的随机发光，包括多种方式：各个激光器发出探测光束的发射时刻随机抖动；激光器的发光顺序在多个激光器中随机选择，即不按照安装顺序从第1个至第N个依次发光，而是在N个激光器中随机选择一个激光器发光，下一次在剩下的N-1个激光器中再随机选择一个激光器发光，或者给N个激光器设定一个随机顺序，按照该随机顺序依次使对应的激光器发光(N为正整数，表示相邻安装的激光器个数)；每个激光器发出的一个探测光束包括多个脉冲，不同激光器发出的探测光束分别所包含的多脉冲之间具有随机的时间间隔；上述几种随机方式的两种或更多种的结合。
结合上述非随机发光方案，分析本发明随机发光方案的技术效果。假设本激光雷达的多个探测器接收到相同数量的干扰信号，因为干扰雷达的发射具有规律性，与非随机发光相比，干扰信号的实际接收时间不变，但本激光雷达的探测光束发射具有随机性，使相邻两个探测器不会同时接收到干扰信号，则产生的多个干扰点对应的水平角度和/或竖直角度不相邻，干扰点的空间距离变大；即使相邻两个探测器仍同时接收到干扰信号，由于本激光雷达的发射时间随机，根据干扰信号计算出的目标物距离也就具有随机性，同样能够增大干扰点的空间距离。因此，点云中出现干扰点的探测角度和/或干扰点对应的距离也产生随机性，降低干扰点的空间相关性而将其暴露出来，使空间孤点判别算法可以识别出来，然后将其滤除。
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。
本发明提供一种激光雷达10，如图2所示，包括激光发射装置11、控制装置12、探测装置13以及数据处理装置14。
激光发射装置11包括激光器111和与其耦接的驱动器112，配置为发射激光脉冲信号。激光发射装置11至少包括一个激光器111及与其对应的驱动器112，图2的实施例中，示出了激光发射装置11包含一个激光器111、一个驱动器112和一个随机数发生器15的实施例的示意图，激光发射装置11包含多个激光器111、多个驱动器112和多个随机数发生器15的实施例将在下文详细描述。激光器111例如可以是激光二极管(laser diode，LD)、边发射激光器(Edge-emitting laser，EEL)或者垂直腔面发射激光器(Vertical-cavity surface-emitting laser，VCSEL)。驱动器112例如可包括开关和电压源或蓄能装置。控制装置向开关发射触发信号，使开关导通，电压源或蓄能装置对激光器放电，从而驱动激光器发射出激光脉冲。
控制装置12与驱动器112耦接，配置成可基于时序随机数产生触发信号，驱动器112接收控制装置12的触发信号并驱动耦接的激光器111发射激光脉冲信号L。时序随机数可以是随机整数或者随机浮点数，可对应于时域上的数字或者时间值，控制装置12根据时序随机数产生触发信号并通过驱动器112来控制激光器111随机发光，以减少干扰。对于每个激光发射装置11，其可以具有一个或多个预设的发射时间，本发明中，控制装置12根据时序随机数来随机调整或者选择激光发射装置11的发射时间。
激光脉冲信号L在目标物上发生漫反射，部分回波信号L’返回到激光雷达10，探测装置13配置为接收所述激光脉冲信号L被目标物反射的回波信号L’，并将所述回波信号L’转换为电信号。所述探测装置13例如可包括雪崩光电二极管(avalanche photodiode，APD)、单光子雪崩二极管(single photon avalanche diode，SPAD)或者其他类型的光电探测器，可以将回波信号转换为电流信号、电压信号、或者数字信号。
数据处理装置14配置成基于发射激光脉冲信号L的时间和接收回波信号L’的时间，确定目标物的距离信息。所述数据处理装置14例如与探测装置13耦接，从而可根据所述电信号计算出回波的接收时间。所述数据处理装置14与所述控制装置12耦接，从而可以获得所述触发信号的触发时刻，作为激光脉冲信号的发射时间。另外的或者可替换的，所述数据处理装置14可以 与所述激光发射装置11耦接，从而获得更精确的激光脉冲信号的发射时间，这些都在本发明的保护范围内。所述数据处理装置14可包括模数转换器ADC、时间数字转换器TDC、微处理器中的一个或多个。
本发明中，控制装置12随机调整或者选择激光发射装置11的发射时间，数据处理装置能够获取该发射时间，并结合探测器接收回波信号的时间计算出光的飞行时间，从而获得准确的目标物距离信息。而干扰信号的发射时间不具有相同的随机性，因此干扰信号的接收时间与本激光雷达随机发射时间的时间差是随机变化的，使得多个干扰信号的时间差及干扰点对应的距离信息不再具有空间相关性，容易被识别出来。
图3a和3b示出了随机发光的信息点三维/二维效果示意图，同样地，激光雷达对相隔一定距离的两个平板形目标物进行探测获得的数据点，图3a中Y轴对应激光雷达的探测水平角度，Z轴对应激光雷达的探测垂直角度，X轴对应探测获得的目标物距离，激光雷达可以根据激光器和相对应探测器的实时探测角度和目标物距离信息获得图3a所示的三维点云。图3b是图3a的X-Y二维图形。采用随机发光的方案后，多个探测器接收到的干扰点不存在空间相关性，如图3a所示，随机发光的激光雷达对两个平板形目标物进行探测获得部分信息点，其中连线上的空心圆代表探测光被目标物反射的真实回波测得的数据点(图示真实点)，星形点代表干扰点。激光雷达不动的情况下，与目标物的距离不变，多个探测器在多个水平角度测得的多个数据点对应同一距离值，在点云上是规则排列的点阵，如图中真实点所示；结合图3b，激光雷达在某一个水平角度(对应相同的Y轴坐标)，多个探测器都收到了干扰信号，由于其他激光雷达未采用同样的随机发光策略，使得干扰点计算获得的距离值在水平角度和垂直角度的形成发散的干扰点，这些干扰点对应的距离信息相差较大，相互之间不具有空间相关性，因而可被识别为空间孤点进行滤除。由此可见，采用随机发光方案，使得干扰激光雷达的干扰点不具有空间相关性，可以通过计算并识别，进而将其作为干扰信号滤除。
继续参考图2所示，根据本发明的一个优选实施例，激光雷达10还包括随机数发生器15，配置为生成时序随机数，控制装置12耦接到随机数发生 器15，以接收所述时序随机数。随机数发生器15为伪随机数发生器，通过以下方式中的一项或多项生成时序随机数：1)查表法，从预先存储的一组随机数表格中随机抽取；2)控制装置12发出触发信号后，随机数发生器15对系统时钟的相位进行采样，将时钟相位转换为时间值，作为时序随机数；3)随机数发生器15读取系统温度，用温度小数位作为随机数种子，产生时序随机数；4)通过线性反馈移位寄存器(Linear feedback shift register，LFSR)产生随机数序列。本领域技术人员可以理解，此处仅对生成方式做简单列举，还可以通过其他方式生成时序随机数，都在本发明的保护范围内。
另外，图2的实施例中，控制装置12与随机数发生器15示出为单独的部件，本发明不限于此，也可以构思将随机数发生器15集成在控制装置12中，或者随机数发生器15并非是激光雷达10的一个组成部件，而是位于激光雷达10的外部，这些都在本发明的保护范围内。
更进一步地，数据处理装置14还配置成可计算多个数据点的相关性，并将相关性低于预设值的距离信息作为干扰信号滤除。由此可见，随机发光方案是使得干扰激光雷达的干扰点不具有空间相关性，使得干扰点与真实点更容易区分开来，这是减少干扰的第一步，然后通过数据处理装置14进行计算并识别，将其作为干扰信号滤除，最终实现减少干扰。所述距离信息的相关性例如包括点云中每个点与相邻点的距离或者每个点与多个相邻点的距离的平均值。在根据本发明得到的激光雷达的点云中，由于干扰源而产生的点通常与相邻点的距离较大，较为分散，因此通过设置距离阈值，可以极大程度上消除或者减少干扰点的数量。
以上对激光雷达10的模块进行了说明，接下来通过优选实施例对随机发光方案的实施进行详细描述。
本发明中，通过随机发光抗干扰的原理是激光雷达10的数据处理装置14能够获知激光器111的实际发光时刻，接收回波的时刻减去实际发光时刻，即可获得的飞行时间(time of flight，tof)，进而换算得到目标物的距离信息，不受发光时刻随机变化的影响。而对于干扰源(其他激光雷达)，因为激光脉冲发射时间是确定的时间值，或者固定的发射间隔且不存在延时， 或由于激光雷达10采用的延时的随机性与干扰源的不同，使得干扰源发出的激光脉冲，或干扰源激光脉冲被同一目标物的反射回波被激光雷达10的探测装置13接收后，减去对应的发射时间得到飞行时间tof值，进而换算得到的距离信息，在空间上不具备相关性，因而可以作为干扰点被滤除。
图4示出了本发明实施例一的发光时刻随机的时序图。对于激光发射装置11的激光器，所述控制装置12中例如可以预先存储多个发光时刻，如图4所示的多个预设发光时刻t1、t2、……、tn，控制装置12从随机数发生器15接收到时序随机数之后，从所述多个预设发光时刻t1、t2、……、tn中根据该时序随机数选取一个发光时刻tx作为该激光器的发光时刻，控制装置12在发光时刻tx发出触发信号，驱动器112接收触发信号，驱动与其耦接的激光器111发出激光脉冲信号。对于激光器111来说，发射单个激光脉冲的时刻具有随机性，而干扰源(其他激光雷达)，因为激光脉冲的发射时间是确定的时间值，当探测装置13接收到两个脉冲信号后，可以容易得识别出干扰信号产生的干扰点，从而实现减少干扰。优选的，所述时序随机数为1-n之间的整数。可替换的，随机数发生器15中预先存储多个预设发光时刻t1、t2、……、tn，随机数发生器生成1-n之间的随机整数x，然后选择预设发光时刻tx并输出给控制装置12。
可替换的，所述随机数发生器15输出的时序随机数为具体的时间值。对于每个激光器111，其发光时刻在0到tmax之间变化，随机数发生器15配置成可以生成0到tmax之间的随机浮点数，作为该时序随机数。控制装置12接收到该随机浮点数之后，在该随机浮点数对应的时刻发出触发信号，以驱动激光器111发出激光脉冲信号。
进一步地，tmax根据一个激光器发光/探测器激活接收对应的一次探测的最长时间间隔确定。例如，最远探测距离200m对应的飞行时间是1.33μs，假设相邻两次探测分配的时间间隔为1.5μs，则tmax不超过0.17μs，以保证下一次探测的正常进行。可根据激光雷达的帧频、转速、线数或分辨率来分配相邻两次探测的时间间隔。
另外，图4中仅示出了单脉冲信号，即一个探测光束仅包含一个脉冲； 本领域技术人员容易理解，激光器发出的激光脉冲信号可以为多脉冲，即一个探测光束包含多个脉冲。图4中所示的多个预设发光时刻t1、t2、……、tn为每个激光器发射的第一个脉冲的发光时刻。
图5示出了本发明实施例二发光延时随机的时序图，对于激光发射装置11的激光器，其每次激光探测脉冲发射都具有一个预设的发光时刻。本发明中，随机数发生器15生成随机发光延时τ，控制装置12将τ作为激光器的发光时刻的延时，从而改变激光器的实际发光时刻。在图5所示的实施例中，激光器每进行一次飞行时间测量，例如发射两个探测脉冲，以激光器111-1为例，两个探测脉冲分别为p1和p1'，探测脉冲p1和p1'的预设的发光时刻分别为t1和t1'，如图5中激光器111-1的发射波形图中实线所示的探测脉冲所示。对于探测脉冲p1，控制装置12根据随机数生成器15生成的随机发光延时τ1，对发光时刻t1进行延时，图中所示的延时τ1为负值，因此实际上时将发光时刻t1进行了提前；同样的，控制装置12根据随机数生成器15生成的随机发光延时τ1'，对发光时刻t1'进行延时，图中所示的延时τ1'为正值，因此实际上时将发光时刻t1'进行了延迟。对于激光器111-1，其两次探测脉冲的发射时刻分别进行了不同的提前和延迟，根据本发明的另一个实施例，同一个激光器在一次飞行时间测量中，多个探测脉冲的延迟也可以是相同的，即具有相同的正负号，并具有相同的绝对值。
或者可替换的，控制装置12也可以预存n个不同的延迟量τ1、τ2、……、τn，其中可包括正负不同的延迟量，随机数发生器15生成1-n范围内的随机整数x并输出给控制装置，控制装置根据所述随机整数x选择延迟量τx，在预设发光时刻加上延时τ1后发出触发信号，对应的驱动器112接收触发信号，驱动激光器111-1发出激光脉冲信号，从而通过发光延时随机的方案实现发光时刻的随机性。更进一步地，激光发射装置11包括多个激光器111，激光器111-1、激光器111-2、激光器111-3……激光器111-n，其中每个激光111具有一个预设发光时刻。随机数发生器15生成随机发光延时τ或者随机整数x，控制装置12据此确定每个激光器111的发光时刻的延时。对应于激光器111-1，控制装置12在预设发光时刻加上延时τ1后发出触发信号， 对应的驱动器112接收触发信号，驱动与之耦接的激光器111-1发出激光脉冲信号；对应于激光器111-2，控制装置12在预设发光时刻加上延时τ2后发出触发信号，对应的驱动器112接收触发信号，驱动与之耦接的激光器111-2发出激光脉冲信号；对应于激光器111-3，控制装置12在预设发光时刻加上延时τ3后发出触发信号，对应的驱动器112接收触发信号，驱动与之耦接的激光器111-3发出激光脉冲信号；依次类推。对于每个激光器的下一次飞行时间测量，重复以上操作。如图5所示，实线脉冲为预设的发光时刻，在预设发光时刻上加上一个延时τ，使各个激光器的实际发光时刻具备随机性。τ的值可以为正值或负值，比如正值表示实际发光时刻比预设发光时刻延迟，如图5中激光器111-3和激光器111-n的第一个激光脉冲所示，虚线脉冲表示的实际发光时刻晚于实线脉冲表示的预设发光时刻；负值表示实际发光时刻比预设发光时刻提前，如图5中激光器111-1和激光器111-2的第一个激光脉冲，虚线脉冲表示的实际发光时刻提前于实线脉冲表示的预设发光时刻。
进一步地，延时τ使干扰点的空间相关性降低，可以预期，该延时τ的值(绝对值)越大，干扰点的空间相关性就越低。在一种孤点判别算法中，可计算点云中每个点与相邻点的距离或者每个点与多个相邻点的距离的平均值，设定相关性距离阈值，若某个点与相邻点的距离大于阈值，则判断该点为干扰点将其滤除。因此，相关性距离阈值应大于真实数据点的距离、小于干扰点可能的距离，在延时τ可能的取值范围内，τ的值越大，干扰点的空间距离越大，相应的相关性距离阈值可以随之增大。
图5中，每个激光器在一次飞行时间测量中发射两个探测脉冲，本发明不限于此，也可以发射一个探测脉冲，或者发射三个或更多数目的探测脉冲，这些都在本发明的保护范围内。
控制装置12除了可以根据时序随机数来调节每个探测脉冲的发射时刻，也可以直接调节一个探测光束中双脉冲之间的时间间隔，此处不再赘述。
根据本发明的另一个实施例，控制装置12根据所述时序随机数来调整多 个激光器的发光顺序。下面参考图6详细描述。
图6a示出了激光器顺序发光时的示意图，图中的激光雷达10正在进行探测，旁边具有作为干扰源的激光雷达10'。为方便介绍，将探测视场划分成二维网格，其中每个方格代表一个子视场，网格的横排和竖列均包括多个子视场。例如激光发射装置11包括一列5个激光器111，探测装置13包括与5个激光器111相对应设置的一列5个探测器，5个激光器111具有预定的发光顺序，与其对应的探测器依次进行探测。当激光雷达10进行测距时，同一列的多个激光器111依次发光，如图6a中1-2-3-4-5的顺序，与其对应的探测器依次接收。若存在干扰源激光雷达10'，以a-b-c-d-e的顺序发出的探测光，激光雷达10和10'探测视场的顺序是一致的，如图6a所示，激光雷达10'发出的探测光产生的回波就可能以相同的顺序被激光雷达10的探测器接收，造成激光雷达10的探测器测得的多个干扰点与真实点之间存在空间相关性而难以滤除。
图6b示出了本发明实施例三的发光顺序随机的干扰示意图，当激光雷达10在测距状态时，同一列的多个激光器111按照3-5-1-2-4的顺序发光，与其对应的探测器按照3-5-1-2-4的顺序接收。若存在干扰源激光雷达10'，以a-b-c-d-e的顺序发出的探测光、或在某一目标物产生的反射光，如图6b所示，就可能以不同的顺序被探测器131接收，探测器131测得的多个干扰点之间不存在空间相关性而容易被滤除。
因此，对于n个激光器，随机数发生器15每次可以产生一个随机整数序列，控制装置12然后按照该随机整数序列来控制n个激光器发射探测脉冲。
发光顺序随机，即多个激光器发光的顺序随机，相当于在发光时刻上施加更大的延时。例如以1-2-3-4-5顺序发光的干扰源，本激光雷达以3-5-1-2-4的顺序发光，即使在各个探测器上都接收到干扰信号，本激光雷达第5探测器接收干扰源第2次发光产生的干扰信号，第4探测器接收干扰源第5次发光产生的干扰信号，干扰源第2次和第5次发光的时间间隔相差很大，则相邻的第4探测器和第5探测器接收干扰信号造成的两个干扰点对应的距离也相差很大，也就容易被暴露为空间孤点。
综上所述，随机发光方案包括发光时刻随机、发光延时随机、发光顺序随机和发光间隔随机四种，四种方案可组合使用，例如发光顺序随机与发光时刻随机相结合，可进一步减小各干扰点的空间相关性。本领域技术人员可以理解，上文通过优选实施例对随机发光方案进行描述，只要基于时序随机数控制激光器的发光时刻，都在本发明的保护范围内。
继续通过实施例四/五/六对实现上述随机发光方案的激光雷达的模块配置进行描述。
图7示出了多个激光器排布的示意图，激光发射装置11包括多个激光器111，如图7中的圆点所示，多个激光器111固定在一个或多个电路板上，通过电路板上安装的激光器个数和电路板安装位置获得不同线密度的分布。本发明上述的随机发光方案可针对每一列激光器分别独立控制；也可以将所有激光器作为整体，每个激光器的发光时刻相对于其他激光器都是随机的。
图8示出了本发明实施例四的激光雷达模块图，激光发射装置11包括多个激光器111-1、111-2、…、111-n以及与激光器数目相同且一一对应耦接的驱动器112-1、112-2、…、112-n，另外，激光雷达10包括与激光器111数目相同且一一对应的随机数发生器15-1、15-2、…、15-n。在激光雷达10的测距状态，控制装置12基于一个随机数发生器15生成的时序随机数产生一个触发信号，与之对应的驱动器112根据触发信号驱动耦接的激光器111发射激光脉冲信号，依次类推，最终每个随机数发生器15对应一个驱动器和一个激光器，可实现发光时刻随机、发光延时随机和发光间隔随机。更进一步地，控制装置12还可以基于多个时序随机数控制多个触发信号的顺序，然后通过对应的驱动器112驱动耦接的激光器111按照随机顺序发光，可实现发光顺序随机的方案。为进一步减小干扰，多个随机发光方案可组合使用。
图9示出了本发明实施例五的激光雷达模块图，激光发射装置11包括多个激光器111-1、111-2、…、111-n以及与激光器数目相同且一一对应耦接的驱动器112-1、112-2、…、112-n，另外，激光雷达10包括一个随机数发生器15。在激光雷达10的测距状态，控制装置12基于随机数发生器15生成的多个时序随机数产生多个触发信号，多个驱动器112根据对应的触发信 号驱动耦接的激光器111发射激光脉冲信号，可实现发光时刻随机、发光延时随机、发光间隔随机和发光顺序随机四种方案中的任一种或者相互组合的方案。
图10示出了本发明实施例六的激光雷达模块图，激光发射装置11包括多个激光器111、与激光器111数目相同且一一对应耦接的驱动器112，将多个激光器111和驱动器112进行分组，例如按照如图7所示的一列激光器111以及相对应的驱动器112分为一组(图7中虚线框所示为一组)，如图10中所示的第一组、…、第n组，每组中的激光器111所测得信息点的相关性较高，因此可以对每组的激光器分别独立控制。激光雷达10包括与分组数相对应的多个随机数发生器15，每个随机数发生器15产生的时序随机数对应一组激光器111和驱动器112，可实现发光时刻随机、发光延时随机、发光间隔随机和发光顺序随机四种方案中的任一种或者相互组合的方案。
以上通过6个优选实施例介绍了随机发光的方案，使干扰激光雷达的干扰点不具有空间相关性，从而容易得区分干扰信号并将其滤除。为进一步提高抗干扰效果，还可以将随机发光方案与多脉冲编码方案相结合，通过判断回波信号的编码是否与发射脉冲序列编码相同，识别回波信号。
继续通过实施例七和八对随机发光方案与多脉冲编码方案进行描述。
根据本发明的一个优选实施例，控制装置12还配置成控制驱动器112驱动耦接的激光器111发射具有多脉冲编码的激光脉冲序列，所述多脉冲编码包括时序编码、幅度编码和/或脉冲宽度编码。
具体地，激光器111发出的探测光为包括N个脉冲的脉冲序列，N为≥2的整数，即多脉冲。
图11示出了本发明实施例七的发光时刻随机结合多脉冲编码的时序图，以N＝2即双脉冲为例，对于激光器111-1，随机数发生器15产生两个时序随机数：t11和t12，其中t11为第一个脉冲的随机发光时刻，t12为第二个脉冲的随机发光时刻。t11和t12均为随机数，使得双脉冲的时序间隔t12-t11也具有随机性。同理，激光器111-2的两个脉冲发光时刻t21、t22……激光器111-n的两个脉冲发光时刻tn1、tn2均为随机数，则双脉冲的时序间隔 t12-t11≠t22-t21≠t32-t31≠……≠tn2-tn1。当N＞2时，激光脉冲序列中包含多个激光脉冲，例如第一脉冲、第二脉冲、……、第N脉冲，多个激光脉冲的发光时刻均基于时序随机数，使多个脉冲前沿的时序间隔随机。同理，可采用发光间隔随机的方案直接对多个脉冲的时序间隔进行设置，可以实现同样的随机效果。与单独采用发光时刻随机方案的区别是，数据处理装置14可以根据时序编码识别出回波信号。
图12示出了本发明实施例八的发光延时随机结合多脉冲编码的时序图，采用固定的发光间隔加上随机事件抖动的方式，以双脉冲为例，给各个激光器111设置固定的两个脉冲的发光时刻，在两个发光时刻上均加上随机延时τ，使第一个脉冲的脉冲前沿随机，即发光时刻随机化；第二个脉冲和第一个脉冲的前沿间隔也就具有随机性，即脉冲时序间隔编码。这是多脉冲编码的另一种时序编码的实现方案，数据处理装置14可以根据时序编码识别出回波信号。
上述编码为在时序上具有间隔的激光脉冲序列，可称为时序编码。同时还可以是在时序上经过脉冲强度调制的脉冲序列，可称为幅度编码，或者两种编码方式的结合，即在时序上具有间隔且经过脉冲强度调制的脉冲序列。此外，还可以基于时序随机数改变脉冲宽度，实现脉冲宽度编码。通过这三种编码的组合，可实现多脉冲的时序间隔、每个脉冲的宽度和每个脉冲的幅度都随机化，数据处理装置14更容易识别出回波信号。具体地，采用多脉冲编码的激光发射装置11，以发射的脉冲编码为第一编码，探测装置13接收回波后，数据处理装置14获取回波脉冲序列的第二编码，判断第二编码是否与第一编码相同，当第二编码与第一编码相同时，将回波作为经过编码的脉冲序列的回波信号。因为发射的脉冲编码具有随机性，使得识别回波脉冲并滤除干扰变得容易，从而提高抗干扰效果。
多脉冲编码的中的幅度编码和脉冲宽度编码主要基于驱动器实现，以下进一步描述。
图13示出了一种多脉冲编码的驱动器结构示意图，驱动器包括多个充电单元以及蓄能装置，当开关触发信号(TRIGGER)控制开关断开时，充电单元在 开关控制信号(GATE1，GATE2,…，GATEN)的控制下，依次对蓄能装置进行充电动作。充电之后，开关触发信号(TRIGGER)控制开关闭合，蓄能装置开始放电，以使得激光器发射激光脉冲。
图14示出了一种多脉冲编码的控制信号与开关触发信号的时序图，开关控制信号(GATE1，GATE2,…，GATEN)结束时触发开关触发信号(TRIGGER)，例如图14中所示的开关控制信号(GATE1，GATE2,…，GATEN)的时序下降沿触发开关触发信号(TRIGGER)的下降沿；如果开关触发信号(TRIGGER)结束是时序信号的上升沿，则将该上升沿作为开关控制信号的触发时机，以保证在充电结束后开始发射过程，并且在前一个充电发光过程结束后，可以立即开始下一个充电-发射过程。
在图14中，开关控制信号(GATE1，GATE2,…，GATEN)的时间宽度是相等的，如此保证发射的脉冲序列中各个脉冲宽度基本一致。另外，可以通过在不同脉冲序列中控制开关控制信号的宽度，可以实现对于发射脉冲强度的控制。例如，开关控制信号GATE1信号与开关控制信号GATE2具有不同的信号时长，那么在蓄能装置中充入的电量也就不同，进而所发射的单个脉冲强度也就不同。根据不同的开关控制信号时长，可以控制实现对于发射脉冲宽度的控制，进而实现对于回波信号的区分，避免不同发射信号序列之间的干扰。
图15示出了另一种多脉冲编码的驱动器结构示意图，多个蓄能装置与电源相连接，每个蓄能装置与一个控制开关相连，控制开关负责控制蓄能装置与激光器的通断。当某一蓄能装置与激光器之间的控制开关闭合时，蓄能装置中存储的电荷驱动激光器发射激光脉冲。
图15中的各个单元开是相互独立的，并且控制开关由控制单元分别独立控制，在时序上的同一时刻，控制单元可以控制控制开关独立地打开或者闭合。当同一时刻存在多个控制开关闭合时，发射激光脉冲能量是几个蓄能装置能量的总和。通过在同一时刻同时闭合多个控制开关以发射高能脉冲，可以实现对于远距离物体的探测。通过控制在时序上闭合的控制开关的个数和时间点，可以控制时序上发射的脉冲形状。例如，在某一时刻，只有1个控 制开关闭合，那么该时刻发射的脉冲强度为1单位，而在后续时刻N个控制开关闭合，那么对应时刻发射的脉冲强度为N个单位。通过控制单元控制在不同时刻闭合开关的数量，可以控制发射脉冲的时序和强度。
综上所述，通过对驱动器的控制可实现对激光脉冲的时序、幅度和脉冲宽度的编码。通过判断回波编码是否与发射激光脉冲序列编码相同，识别出回波信号，进一步提高抗干扰效果。
本发明还提供一种测距方法100，如图16所示，所述方法包括：
在步骤S101：生成时序随机数；
在步骤S102：基于所述时序随机数，控制激光发射装置的至少一个驱动器驱动相耦接的激光器发射激光脉冲信号；
在步骤S103：接收所述激光脉冲信号被目标物反射的回波信号；和
在步骤S104：基于所述激光脉冲信号发射时间和接收回波信号的时间，确定所述目标物的距离信息。
根据本发明的一个方面，还包括：计算多个距离信息的相关性，将相关性低于预设值的距离信息判断为干扰信号。
根据本发明的一个方面，其中所述步骤S102包括：基于所述时序随机数，控制激光器发射所述激光脉冲信号的发射时间，和/或控制相邻激光脉冲之间的时间间隔。
根据本发明的一个方面，其中所述步骤S102包括：基于所述时序随机数，控制多个激光器的发光顺序。
根据本发明的一个方面，其中所述步骤S102包括通过以下方式生成时序随机数：
从预存的随机数表格中随机抽取；
基于时钟相位生成；
基于系统温度生成；和
通过线性反馈移位寄存器生成。
本发明还提供一种激光雷达20，如图17所示，包括：激光发射装置21、控制装置22、探测装置23以及数据处理装置24，其中，
所述控制装置22，配置成可基于时序随机数产生触发信号；
所述激光发射装置21，包括至少一个激光器211和与所述激光器211耦接的驱动器212，所述驱动器212配置成根据所述触发信号驱动所述激光器211发射激光脉冲信号；
所述探测装置23，配置为接收所述激光脉冲信号被目标物反射的回波信号，并将所述回波信号转换为电信号；和
所述数据处理装置24，基于发射所述激光脉冲信号的时间和接收所述回波信号的时间，确定所述目标物的距离信息，
所述激光脉冲信号为具有多脉冲编码的激光脉冲序列，所述多脉冲编码包括时序编码、幅度编码和/或脉冲宽度编码。
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。

Claims (17)

  1. 一种激光雷达，包括：激光发射装置、控制装置、探测装置以及数据处理装置，其中，
    所述控制装置配置成可基于时序随机数产生触发信号；
    所述激光发射装置包括至少一个激光器和与所述激光器耦接的驱动器，所述驱动器配置成根据所述触发信号驱动所述激光器发射激光脉冲信号；
    所述探测装置配置为接收所述激光脉冲信号被目标物反射的回波信号，并将所述回波信号转换为电信号；和
    所述数据处理装置配置成基于发射所述激光脉冲信号的时间和接收所述回波信号的时间，确定所述目标物的距离信息。
  2. 如权利要求1所述的激光雷达，还包括随机数发生器，配置为生成所述时序随机数，所述控制装置耦接到所述随机数发生器，以接收所述时序随机数。
  3. 如权利要求1所述的激光雷达，其中所述数据处理装置配置成可计算多个距离信息的相关性，并将相关性低于预设值的距离信息作为干扰信号滤除。
  4. 如权利要求2所述的激光雷达，其中所述激光器具有多个预设的发光时刻，所述控制装置配置成：根据所述时序随机数，从所述多个预设的发光时刻中选取一个发光时刻，作为所述驱动信号的触发时刻。
  5. 如权利要求2所述的激光雷达，其中所述激光器具有一个预设的发光时刻，所述控制装置配置成：根据所述时序随机数，对所述预设的发光时刻进行延迟或提前，作为所述驱动信号的触发时刻。
  6. 如权利要求2所述的激光雷达，其中所述激光器配置成可发射多个脉冲，所述控制装置配置成可根据所述时序随机数调整相邻的两个脉冲对应的触发信号之间的时间间隔。
  7. 如权利要求2-6中任一项所述的激光雷达，其中所述激光发射装置包括数 目相同的多个激光器和多个驱动器，所述激光雷达包括与所述激光器数目相同的多个随机数发生器。
  8. 如权利要求2-6中任一项所述的激光雷达，其中所述激光发射装置包括多个激光器以及与所述激光器一一耦接的多个驱动器，所述控制装置与所述多个驱动器耦接，所述时序随机数对应多个激光器的发光顺序。
  9. 如权利要求2-6中任一项所述的激光雷达，其中所述激光发射装置包括多组激光器，每组激光器包括多个激光器及与所述激光器一一耦接的多个驱动器，所述激光雷达还包括与所述多组激光器对应的多个随机数发生器，每个随机数发生器产生的时序随机数和与其对应的一组激光器的发光顺序相对应。
  10. 如权利要求2-6中任一项所述的激光雷达，其中所述控制装置还配置成控制所述驱动器驱动所述激光器发射具有多脉冲编码的激光脉冲序列，所述多脉冲编码包括时序编码、幅度编码和/或脉冲宽度编码。
  11. 如权利要求2-6中任一项所述的激光雷达，其中所述随机数发生器为伪随机数发生器，通过以下方式中的一项或多项生成所述时序随机数：
    从预存的随机数表格中随机抽取；
    基于时钟相位生成；
    基于系统温度生成；和
    通过线性反馈移位寄存器生成。
  12. 一种测距方法，所述方法包括：
    S101：生成时序随机数；
    S102：基于所述时序随机数，控制激光发射装置的至少一个驱动器驱动相耦接的激光器发射激光脉冲信号；
    S103：接收所述激光脉冲信号被目标物反射的回波信号；和
    S104：基于所述激光脉冲信号发射时间和接收回波信号的时间，确定所述目标物的距离信息。
  13. 如权利要求12所述的测距方法，还包括：计算多个距离信息的相关性，将相关性低于预设值的距离信息判断为干扰信号。
  14. 如权利要求12所述的测距方法，其中所述步骤S102包括：基于所述时序随机数，控制激光器发射所述激光脉冲信号的发射时间，和/或控制相邻激光脉冲之间的时间间隔。
  15. 如权利要求12-14中任一项所述的测距方法，其中所述步骤S102包括：基于所述时序随机数，控制多个激光器的发光顺序。
  16. 如权利要求12-14中任一项所述的方法，其中所述步骤S102包括通过以下方式生成时序随机数：
    从预存的随机数表格中随机抽取；
    基于时钟相位生成；
    基于系统温度生成；和
    通过线性反馈移位寄存器生成。
  17. 一种激光雷达，包括：激光发射装置、控制装置、探测装置以及数据处理装置，其中，
    所述控制装置配置成可基于时序随机数产生触发信号；
    所述激光发射装置包括至少一个激光器和与所述激光器耦接的驱动器，所述驱动器配置成根据所述触发信号驱动所述激光器发射激光脉冲信号；
    所述探测装置，配置为接收所述激光脉冲信号被目标物反射的回波信号，并将所述回波信号转换为电信号；和
    所述数据处理装置，基于发射所述激光脉冲信号的时间和接收所述回波信号的时间，确定所述目标物的距离信息，
    所述激光脉冲信号为具有多脉冲编码的激光脉冲序列，所述多脉冲编码包括时序编码、幅度编码和/或脉冲宽度编码。
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