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WO2022036714A1 - Module de télémétrie par laser, dispositif de télémétrie et plateforme mobile - Google Patents

Module de télémétrie par laser, dispositif de télémétrie et plateforme mobile Download PDF

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Publication number
WO2022036714A1
WO2022036714A1 PCT/CN2020/110606 CN2020110606W WO2022036714A1 WO 2022036714 A1 WO2022036714 A1 WO 2022036714A1 CN 2020110606 W CN2020110606 W CN 2020110606W WO 2022036714 A1 WO2022036714 A1 WO 2022036714A1
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WIPO (PCT)
Prior art keywords
time interval
pulse signal
return light
light pulse
preset
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Ceased
Application number
PCT/CN2020/110606
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English (en)
Chinese (zh)
Inventor
许友
王栗
梅雄泽
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SZ DJI Technology Co Ltd
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SZ DJI Technology Co Ltd
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Priority to PCT/CN2020/110606 priority Critical patent/WO2022036714A1/fr
Priority to CN202080013349.2A priority patent/CN114391112A/zh
Publication of WO2022036714A1 publication Critical patent/WO2022036714A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • 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
    • G01S7/495—Counter-measures or counter-counter-measures using electronic or electro-optical means

Definitions

  • Embodiments of the present invention relate to the technical field of ranging, and more particularly, to a laser ranging method, a ranging device, and a movable platform.
  • Laser ranging devices such as three-dimensional point cloud detection systems such as lidar and laser rangefinders can measure the time of light travel between the ranging device and the measured object, that is, the time-of-flight (TOF) of light. ) to detect the distance from the detected object to the ranging device.
  • This type of laser ranging device emits a beam of laser pulses from the transmitting end, which is reflected by the measured object, and the receiving end receives the reflected signal of the measured object to form a receiving pulse. Calculate the distance between the laser ranging device and the measured object.
  • TOF time-of-flight
  • the receiving end of the laser ranging device will also receive the pulse signal reflected from the laser pulse not emitted by itself, that is, receive the interference signal.
  • the phenomenon of interference is very common. For example, when two lidars work at the same time, the receiver of one lidar is likely to receive the laser pulses directly emitted by the other lidar, or receive the laser pulses emitted by the other lidar. reflected laser pulses.
  • the interference signal will cause the lidar to be unable to effectively identify the interference information in the received pulse, so that it can calculate the wrong distance value, so that it cannot perform correct detection.
  • the first aspect of the embodiments of the present invention provides a laser ranging method, including:
  • the preset time interval and the receiving time determine the effective return light pulse signal of the at least two laser pulse signals reflected by the measured object
  • the distance between the distance measuring device and the measured object is determined according to the receiving time of the effective return light pulse signal.
  • a second aspect of the embodiments of the present invention provides a distance measuring device, including:
  • a transmitting circuit for continuously transmitting at least two laser pulse signals according to a preset time interval
  • the receiving circuit is used to receive the optical pulse signal
  • a sampling circuit for determining the receiving time of the return light pulse signal
  • an arithmetic circuit configured to determine, in the return light pulse signal, the effective return light pulse signal reflected by the object to be measured from the at least two laser pulse signals according to the preset time interval and the receiving time, and according to the returned light pulse signal
  • the receiving time of the effective return light pulse signal determines the distance between the distance measuring device and the measured object.
  • a third aspect of the embodiments of the present invention provides a movable platform, the movable platform includes a movable platform body and the above-mentioned distance measuring device, and the distance measuring device is mounted on the movable platform body.
  • the laser ranging method, the ranging device and the movable platform according to the embodiments of the present invention transmit at least two laser pulse signals continuously, and extract the effective return light pulse signal from the return light pulse signal according to the receiving time of the return light pulse signal, so as to effectively It can identify and filter interfering signals to improve the robustness and anti-interference ability of the ranging device.
  • FIG. 1 is a schematic frame diagram of a distance measuring device according to an embodiment of the present invention
  • FIG. 2 is a schematic diagram of an embodiment in which a distance measuring device according to an embodiment of the present invention adopts a coaxial optical path;
  • FIG. 3 is a schematic diagram of a scanning pattern of a laser radar according to an embodiment of the present invention.
  • Figure 4 is a schematic diagram of laser ranging based on the time of flight of light
  • FIG. 5 is a schematic diagram of an effective return light pulse signal and an interference signal received by the ranging device
  • FIG. 6 is a schematic flowchart of a laser ranging method according to an embodiment of the present invention.
  • FIG. 7 is a schematic diagram of an effective return light pulse signal and an interference signal received by a ranging device in a laser ranging method according to an embodiment of the present invention
  • FIG. 8 is a flowchart of an algorithm for determining an effective return light pulse signal and an interference signal in a laser ranging method according to an embodiment of the present invention.
  • the laser ranging method provided by the various embodiments of the present invention can be applied to a ranging device, and the ranging device can be an electronic device such as a laser radar or a laser ranging device.
  • the ranging device is used to sense external environmental information, for example, distance information, orientation information, reflection intensity information, speed information and the like of environmental objects.
  • the ranging device can detect the distance from the detected object to the ranging device by measuring the time of light propagation between the ranging device and the detected object, that is, the time-of-flight (TOF) of light.
  • TOF time-of-flight
  • the ranging apparatus 100 may include a transmitting circuit 110 , a receiving circuit 120 , a sampling circuit 130 and an arithmetic circuit 140 .
  • the transmit circuit 110 may transmit a sequence of optical pulses (eg, a sequence of laser pulses).
  • the receiving circuit 120 can receive the optical pulse sequence reflected by the detected object, and perform photoelectric conversion on the optical pulse sequence to obtain an electrical signal, which can be output to the sampling circuit 130 after processing the electrical signal.
  • the sampling circuit 130 may sample the electrical signal to obtain a sampling result.
  • the arithmetic circuit 140 may determine the distance between the distance measuring device 100 and the detected object based on the sampling result of the sampling circuit 130 .
  • the distance measuring device 100 may further include a control circuit 150, which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.
  • a control circuit 150 can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.
  • the distance measuring device shown in FIG. 1 includes a transmitting circuit, a receiving circuit, a sampling circuit and an arithmetic circuit for emitting a beam of light for detection
  • the embodiment of the present application is not limited to this, the transmitting circuit
  • the number of any one of the receiving circuits, sampling circuits, and arithmetic circuits may also be at least two, for emitting at least two light beams in the same direction or in different directions respectively; wherein, the at least two light beam paths can be simultaneously
  • the ejection can also be ejected at different times.
  • the light-emitting chips in the at least two emission circuits are packaged in the same module.
  • each emitting circuit includes one laser emitting chip, and the dies in the laser emitting chips in the at least two emitting circuits are packaged together and accommodated in the same packaging space.
  • the ranging apparatus 100 may further include a scanning module for changing the propagation direction of at least one laser pulse sequence emitted from the transmitting circuit.
  • the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130 and the operation circuit 140, or the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, the operation circuit 140 and the control circuit 150 may be referred to as the measuring circuit A ranging module, which can be independent of other modules, such as a scanning module.
  • a coaxial optical path may be used in the ranging device, that is, the light beam emitted by the ranging device and the reflected light beam share at least part of the optical path in the ranging device.
  • the laser pulse sequence reflected by the detection object passes through the scanning module and then enters the receiving circuit.
  • the distance-measuring device may also adopt an off-axis optical path, that is, the light beam emitted by the distance-measuring device and the reflected light beam are respectively transmitted along different optical paths in the distance-measuring device.
  • FIG. 2 shows a schematic diagram of an embodiment in which the distance measuring device of the present invention adopts a coaxial optical path.
  • the ranging apparatus 200 includes a ranging module 210, and the ranging module 210 includes a transmitter 203 (which may include the above-mentioned transmitting circuit), a collimating element 204, a detector 205 (which may include the above-mentioned receiving circuit, sampling circuit and arithmetic circuit) and Optical path changing element 206 .
  • the ranging module 210 is used for emitting a light beam, receiving the returning light, and converting the returning light into an electrical signal.
  • the transmitter 203 can be used to transmit a sequence of optical pulses.
  • the transmitter 203 may emit a sequence of laser pulses.
  • the laser beam emitted by the transmitter 203 is a narrow bandwidth beam with a wavelength outside the visible light range.
  • the collimating element 204 is disposed on the outgoing light path of the transmitter, and is used for collimating the light beam emitted from the transmitter 203, and collimating the light beam emitted by the transmitter 203 into parallel light and outputting to the scanning module.
  • the collimating element also serves to converge at least a portion of the return light reflected by the probe.
  • the collimating element 204 may be a collimating lens or other elements capable of collimating light beams.
  • the transmitting optical path and the receiving optical path in the ranging device are combined by the optical path changing element 206 before the collimating element 204, so that the transmitting optical path and the receiving optical path can share the same collimating element, so that the optical path more compact.
  • the emitter 203 and the detector 205 may use respective collimating elements, and the optical path changing element 206 may be arranged on the optical path behind the collimating element.
  • the optical path changing element can use a small-area reflective mirror to The transmit light path and the receive light path are combined.
  • the optical path changing element may also use a reflector with a through hole, wherein the through hole is used to transmit the outgoing light of the emitter 203 , and the reflector is used to reflect the return light to the detector 205 . This can reduce the shielding of the return light by the bracket of the small reflector in the case of using a small reflector.
  • the optical path altering element is offset from the optical axis of the collimating element 204 .
  • the optical path altering element may also be located on the optical axis of the collimating element 204 .
  • the ranging device 200 further includes a scanning module 202 .
  • the scanning module 202 is placed on the outgoing optical path of the ranging module 210 .
  • the scanning module 202 is used to change the transmission direction of the collimated beam 219 emitted by the collimating element 204 and project it to the external environment, and project the return light to the collimating element 204 .
  • the returned light is focused on the detector 205 via the collimating element 104 .
  • the scanning module 202 can include at least one optical element for changing the propagation path of the light beam, wherein the optical element can change the propagation path of the light beam by reflecting, refracting, diffracting the light beam, or the like.
  • the scanning module 202 includes lenses, mirrors, prisms, gratings, liquid crystals, optical phased arrays (Optical Phased Array) or any combination of the above optical elements.
  • at least part of the optical elements are moving, for example, the at least part of the optical elements are driven to move by a driving module, and the moving optical elements can reflect, refract or diffract the light beam to different directions at different times.
  • the multiple optical elements of the scanning module 202 may be rotated or oscillated about a common axis 209, each rotating or oscillating optical element being used to continuously change the propagation direction of the incident beam.
  • the plurality of optical elements of the scanning module 202 may rotate at different rotational speeds, or vibrate at different speeds.
  • at least some of the optical elements of scan module 202 may rotate at substantially the same rotational speed.
  • the plurality of optical elements of the scanning module may also be rotated about different axes.
  • the plurality of optical elements of the scanning module may also rotate in the same direction, or rotate in different directions; or vibrate in the same direction, or vibrate in different directions, which are not limited herein.
  • the scanning module 202 includes a first optical element 214 and a driver 216 connected to the first optical element 214, and the driver 216 is used to drive the first optical element 214 to rotate around the rotation axis 209, so that the first optical element 214 changes The direction of the collimated beam 219.
  • the first optical element 214 projects the collimated beam 219 in different directions.
  • the angle between the direction of the collimated light beam 219 changed by the first optical element and the rotation axis 209 changes with the rotation of the first optical element 214 .
  • the first optical element 214 includes a pair of opposing non-parallel surfaces through which the collimated beam 219 passes.
  • the first optical element 214 includes a prism whose thickness varies along at least one radial direction.
  • the first optical element 214 includes a wedge prism that refracts the collimated light beam 219 .
  • the scanning module 202 further includes a second optical element 215 , the second optical element 215 rotates around the rotation axis 209 , and the rotation speed of the second optical element 215 is different from the rotation speed of the first optical element 214 .
  • the second optical element 215 is used to change the direction of the light beam projected by the first optical element 214 .
  • the second optical element 215 is connected to another driver 217, and the driver 217 drives the second optical element 215 to rotate.
  • the first optical element 214 and the second optical element 215 can be driven by the same or different drivers, so that the rotational speed and/or steering of the first optical element 214 and the second optical element 215 are different, thereby projecting the collimated beam 219 into the external space Different directions can scan a larger spatial range.
  • the controller 218 controls the drivers 216 and 217 to drive the first optical element 214 and the second optical element 215, respectively.
  • the rotational speeds of the first optical element 214 and the second optical element 215 may be determined according to the area and pattern expected to be scanned in practical applications.
  • Drives 216 and 217 may include motors or other drives.
  • the second optical element 215 includes a pair of opposing non-parallel surfaces through which the light beam passes.
  • the second optical element 215 comprises a prism whose thickness varies along at least one radial direction.
  • the second optical element 215 comprises a wedge prism.
  • the scanning module 202 further includes a third optical element (not shown) and a driver for driving the movement of the third optical element.
  • the third optical element includes a pair of opposing non-parallel surfaces through which the light beam passes.
  • the third optical element comprises a prism of varying thickness along at least one radial direction.
  • the third optical element comprises a wedge prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or rotations.
  • each optical element in the scanning module 202 can project light in different directions, such as light 211 and 213 , so as to scan the space around the ranging device 200 .
  • FIG. 3 is a schematic diagram of a scanning pattern of the distance measuring device 200 . It can be understood that when the speed of the optical element in the scanning module changes, the scanning pattern also changes accordingly.
  • the scanning module 202 When the light 211 projected by the scanning module 202 hits the detected object 201 , a part of the light is reflected by the detected object 201 to the distance measuring device 200 in a direction opposite to the projected light 211 .
  • the returning light 212 reflected by the probe 201 passes through the scanning module 202 and then enters the collimating element 204 .
  • a detector 205 is placed on the same side of the collimating element 204 as the emitter 203, and the detector 205 is used to convert at least part of the return light passing through the collimating element 204 into an electrical signal.
  • each optical element is coated with an anti-reflection coating.
  • the thickness of the anti-reflection film is equal to or close to the wavelength of the light beam emitted by the emitter 203, which can increase the intensity of the transmitted light beam.
  • a filter layer is coated on the surface of an element located on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path for transmitting at least the wavelength band of the light beam emitted by the transmitter, Reflects other bands to reduce noise from ambient light to the receiver.
  • the transmitter 203 may comprise a laser diode through which laser pulses are emitted on the nanosecond scale.
  • the laser pulse receiving time can be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse to determine the laser pulse receiving time.
  • the ranging apparatus 200 can calculate the TOF by using the pulse receiving time information and the pulse sending time information, so as to determine the distance from the probe 201 to the ranging apparatus 200 .
  • the distance and orientation detected by the ranging device 200 can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like.
  • the distance measuring device of the embodiment of the present invention can be applied to a movable platform, and the distance measuring device can be installed on the movable platform body of the movable platform.
  • the movable platform with the distance measuring device can measure the external environment, for example, measure the distance between the movable platform and obstacles for obstacle avoidance and other purposes, and perform two-dimensional or three-dimensional mapping of the external environment.
  • the movable platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera.
  • the movable platform body When the ranging device is applied to the unmanned aerial vehicle, the movable platform body is the fuselage of the unmanned aerial vehicle.
  • the movable platform body When the distance measuring device is applied to an automobile, the movable platform body is the body of the automobile.
  • the vehicle may be an autonomous driving vehicle or a semi-autonomous driving vehicle, which is not limited herein.
  • the movable platform body When the distance measuring device is applied to the remote control car, the movable platform body is the body of the remote control car.
  • the movable platform body When the distance measuring device is applied to the robot, the movable platform body is the robot.
  • the ranging device When the ranging device is applied to the camera, the movable platform body is the camera itself.
  • the ranging principle of the Time-of-Flight (TOF) method is as follows: the transmitter of the ranging device emits a laser pulse, and at the same time, the receiver enters a receivable state, and after a period of time After the laser pulse is reflected back to the receiving end of the ranging device by the measured object, the reflected signal of the measured object is received, and a return light pulse signal is formed . Calculate the distance between the measured object and the distance measuring device.
  • TOF Time-of-Flight
  • the T 0 pulse is the return light pulse signal reflected on the measured object by the laser pulse emitted by the laser ranging device itself, which is defined as an effective return light pulse signal in this application; Then, in the time window in which the receiving end waits to receive the valid return optical pulse signal, there may be interference signals received by the receiving end, namely T noise_0 and T noise_1 in FIG. 5 , which are defined as interference signals in this application.
  • the interference signals such as The laser pulse signal emitted by other ranging devices, the reflected light signal of the laser pulse emitted by other ranging devices reflected by the object, or the stray light signal formed by the reflection of the laser pulse signal emitted by the ranging device itself inside the ranging device .
  • T 0 , T noise_0 and T noise_1 have no difference to the receiving end, so the ranging device cannot correctly identify and filter the interference signal, nor can it measure according to the effective return light pulse signal Correct detection distance value.
  • FIG. 6 shows a schematic flowchart of a laser ranging method 600 according to an embodiment of the present invention. As shown in FIG. 6, the laser ranging method 600 includes the following steps:
  • step S610 at least two laser pulse signals are continuously emitted according to a preset time interval
  • step S620 receiving the back light pulse signal, and determining the receiving time of the back light pulse signal
  • step S630 according to the preset time interval and the receiving time, determine the effective return light pulse signals reflected back by the measured object from the at least two laser pulse signals in the return light pulse signals;
  • step S640 the distance between the distance measuring device and the measured object is determined according to the receiving time of the effective return light pulse signal.
  • the laser ranging method continuously transmits at least two laser pulse signals at a preset time interval in a short period of time in the transmitting stage.
  • the return light pulse signal reflected by the measured object from the at least two emitted laser pulse signals is extracted in time, so as to effectively distinguish the effective return light pulse signal and the interference signal in the return light pulse signal.
  • the number of continuously emitted laser pulse signals may be two or three or more. If the number of continuously emitted laser pulse signals is at least three, the number of consecutively emitted laser pulse signals is The preset time interval between the two laser pulses may be the same or different; the following description will mainly take the continuous emission of two laser pulse signals as an example.
  • At least two laser pulse signals may be transmitted by the transmitting circuit of the ranging device.
  • the transmitting circuit includes a laser transmitter such as a laser diode, through which laser pulses of nanosecond level can be transmitted; at least two laser pulse signals can be continuously transmitted through the same transmitting circuit of the ranging device, or can be transmitted through different ranging devices.
  • the transmit circuits are turned on at the same time and transmit separately.
  • the emission directions of the at least two laser pulse signals are the same, and since the at least two laser pulse signals are continuously emitted in a short period of time, they can be irradiated on the same object to be measured.
  • the preset time interval between two adjacent laser pulse signals is subject to certain constraints. First, considering that the two laser pulse signals cannot affect each other, the preset time interval between transmitting two adjacent laser pulse signals is not less than the charging and discharging time of the distance measuring device, specifically, not less than the transmitting laser pulse signal.
  • the charging and discharging time of the laser is determined to avoid that the laser is still charged at the time point after the emission of a laser pulse signal, thereby affecting the normal emission of the laser pulse signal. For example, if the charging and discharging time is 50ns, the preset time interval is not less than 50ns.
  • the preset time interval should not be too long.
  • the preset time interval is not greater than the difference between the sampling interval time of the ranging device and the time-of-flight (TOF) corresponding to the range limit of the ranging device, so as to avoid being damaged at the measurement range limit.
  • TOF time-of-flight
  • the receiving time of the return light pulse signal of the first laser pulse signal in the two adjacent laser pulse signals is 3.3333us
  • the preset time interval between two adjacent laser pulse signals is fixed. In other embodiments, the preset time interval between two adjacent laser pulse signals can be modulated, and before step S610, it also includes modulating the preset time interval between two adjacent laser pulse signals .
  • modulation modes of the preset time interval are described below, but it should be noted that the modulation modes of the preset time interval are not limited to the following:
  • the first modulation method may be called a random number method, that is, the preset time interval ⁇ T is randomly generated between a preset minimum time interval T min and a preset maximum time interval T max .
  • the random number generating function rand( ) can be used to generate ⁇ T randomly, and the upper and lower limits of the random number generating function are set as T max and T min respectively.
  • T max may correspond to the difference between the sampling interval time of the distance measuring device and the TOF corresponding to the range limit
  • T min may correspond to the charging and discharging time of the distance measuring device.
  • the second modulation method may be called a fixed value method, that is, a fixed value is taken between a preset minimum time interval T min and a preset maximum time interval T max as the preset time interval ⁇ T.
  • the size of the fixed value is negatively correlated with the distance between the measured object and the ranging device, that is to say, the farther the distance between the measured object and the ranging device, the closer ⁇ T is At T min , the closer the distance between the measured object and the ranging device, the closer ⁇ T is to T max .
  • the reason is that part of the interference signal may be the reflected light of the outgoing laser pulse signal reflected in the ranging device itself and incident on the receiving end, and its TOF is short.
  • the distance between the measured object and the ranging device is short, Then, there may be a phenomenon that the effective return light pulse signal is fused with this part of the emitted light, so the method of increasing the preset time interval is adopted to avoid the difficulty in identifying the effective return light pulse signal due to the occurrence of the fusion phenomenon.
  • the distance between the measured object and the ranging device is accurately calculated in the subsequent steps, when the measured object is located in the region of interest, the distance between the region of interest and the ranging device has a predetermined Therefore, the distance range between the measured object and the distance measuring device can be determined according to the distance between the region of interest and the distance measuring device, and the corresponding preset time interval can be selected according to the distance range.
  • the third modulation method can be called the random number method with limited value.
  • the preset time interval in the time interval list is selected between the minimum time interval T min and the preset maximum time interval T max .
  • the preset time interval may also be selected between a preset minimum time interval and a preset maximum time interval based on the motion state of the distance measuring device or the motion state of the measured object.
  • the size of the preset time interval is negatively correlated with the motion speed of the distance measuring device or the motion speed of the measured object, or in other words, the size of the preset time interval is related to the relative motion speed between the distance measuring device and the measured object. is a negative correlation, that is, the faster the measured object moves relative to the ranging device, the smaller the preset time interval; the slower the measured object moves relative to the ranging device, the larger the preset time interval.
  • a smaller preset time interval can be used to avoid the distance between the measured object and the distance measuring device when different laser pulse signals are irradiated to the measured object.
  • the distance difference is too large, so as to prevent the interval between the effective return light pulse signals and the preset time interval from being too large, and improve the success rate of extracting the effective return light pulse signal.
  • the modulation mode for modulating the preset time interval may be selected according to the current scene. For example, if the moving speed or distance of the measured object in the current scene has a wide distribution range and great uncertainty, such as a road scene, the random number method or the random number method with limited values can be selected to share the error or limited Random number method for the value. Similarly, if the current scene cannot be determined, the random number method can also be used. Alternatively, if the measured object in the current scene is mainly in a static state, for example, if the current scene is an indoor scene, a fixed value method may be used to modulate the preset time interval. Exemplarily, the mapping relationship between each scene and the corresponding modulation mode may be preset, and when the user selects the current scene or the ranging device itself recognizes the current scene, the modulation mode suitable for the current scene is selected according to the mapping relationship.
  • the modulation mode for modulating the preset time interval may be selected according to the distance between the measured object and the distance measuring device. For example, when the distance distribution range is wide, the random number method or the random number method with limited value can be used; when the distance distribution range is narrow, the fixed value method can be used. Alternatively, the modulation method for modulating the preset time interval can be selected according to the motion state of the measured object or the ranging device.
  • the motion state based on the ranging device can be used
  • the motion state of the object to be measured is between the preset minimum time interval and the preset maximum time interval to select the modulation mode of the preset time interval; when the measured object and the distance measuring device are in a static state, a fixed value can be used Law.
  • the modulation mode for modulating the preset time interval can also be selected according to the user's instruction.
  • step S620 a back light pulse signal is received, and the receiving time of the back light pulse signal is determined.
  • the receiving circuit of the ranging device receives the optical signal through the photosensitive element, and the photosensitive element includes but is not limited to photodiode, avalanche photodiode or charge coupled element, and converts the received optical signal into an electrical signal.
  • the photosensitive element sends the electrical signal to the primary or secondary amplifying circuit for amplification, and sends the amplified electrical signal to the sampling circuit.
  • the sampling circuit includes a comparator (for example, an analog comparator (COMP) for converting an electrical signal into a digital pulse signal) and a time measurement circuit, via a primary or secondary amplifier circuit The amplified electrical signal enters the time measurement circuit after passing through the comparator, and the time measurement circuit conducts counts.
  • a comparator for example, an analog comparator (COMP) for converting an electrical signal into a digital pulse signal
  • the time measurement circuit may be a time-to-data converter (Time-to-Data Converter, TDC).
  • TDC can be an independent TDC chip, or based on Field-Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC) or Complex Programmable Logic Device , the internal delay chain of programmable devices such as CPLD to realize the TDC circuit of time measurement, or the circuit structure of time measurement by using high frequency clock or the circuit structure of time measurement by counting method.
  • FPGA Field-Programmable Gate Array
  • ASIC Application Specific Integrated Circuit
  • CPLD Complex Programmable Logic Device
  • the first input terminal of the comparator is used to receive an electrical signal input from the amplifying circuit, and the electrical signal may be a voltage signal or a current signal; the second input terminal of the comparator is used to receive a preset threshold value, which is input to the comparator.
  • the electrical signal of the device is compared with a preset threshold.
  • the output signal of the comparator is connected to the TDC, and the TDC can measure the time information of the output signal edge of the comparator. The measured time is based on the transmission time of the optical pulse signal, that is, the time difference between the transmission and reception of the laser pulse signal can be measured. .
  • the sampling module may also include an analog-to-digital converter (Analog-to-Digital Converter, ADC). After the analog signal input to the sampling module is converted by the ADC, the digital signal can be output to the operation module.
  • ADC Analog-to-Digital Converter
  • Interference signals include but are not limited to laser pulses emitted by other ranging devices, laser pulses emitted by other ranging devices reflected by objects, and laser pulses emitted by the ranging device itself reflected on the inner surface of the ranging device. stray light.
  • the ranging device cannot identify the valid return light pulse signal and the interference signal in the receiving stage. In this stage, the receiving time of each return light pulse signal needs to be determined, so as to be used to determine the return light pulse signal according to the receiving time in the subsequent step S630.
  • Valid return light pulse signal is not limited to laser pulses emitted by other ranging devices, laser pulses emitted by other ranging devices reflected by objects, and laser pulses emitted by the ranging device itself reflected on the inner surface of the ranging device.
  • Step S630 may be implemented by an arithmetic circuit of the distance measuring device.
  • a valid return light pulse signal is identified from the plurality of return light pulse signals by comparing the time interval between every two return light pulse signals with a preset time interval.
  • the ranging device receives four return light pulse signals in step S620, namely T0, T1, T2, T3, among which T0 and T1
  • the time interval with other return light pulse signals deviates from the preset time interval, so it is an interference signal, and the time interval between T2 and T3 is approximately equal to the preset time interval, which is an effective return light pulse signal.
  • the pulse width of the return light pulse signal is nanosecond level
  • the time window is millisecond level
  • the interference signal is randomly distributed in the current time window
  • the interference The probability that the time interval between signals or the time interval between the interference signal and the valid return light pulse signal is close to or equal to the preset time interval is extremely low. In general, only the time interval between the valid return light pulse signals can be approximately equal to Preset time interval.
  • the time interval between two valid return light pulse signals is difficult to be strictly equal to the preset time interval, so as long as the time interval between the receiving times of adjacent return light pulse signals is the same as the preset time interval If the deviation between the time intervals is not greater than the preset threshold, it can be regarded as a valid return light pulse signal.
  • the preset threshold is not less than the timing accuracy of the timer used to determine the receiving time of the return light pulse signal, so as to ensure that the distance measuring device can distinguish the two return light pulse signals.
  • an algorithm flow for identifying valid return light pulse signals is: if the current first return light pulse signal is not the last return light pulse signal, then Calculate the time interval between the first return light pulse signal and each return light pulse signal after the first return light pulse signal in turn; if the time interval between the first return light pulse signal and the subsequent second return light pulse signal is equal to If the deviation between the preset time intervals is not greater than the preset threshold, it is determined that the first return light pulse signal and the second return light pulse signal are valid return light pulse signals; if the first return light pulse signal and the first return light pulse signal are valid return light pulse signals; The deviation between the time interval between the subsequent return light pulse signals and the preset time interval is greater than the preset threshold value, then it is determined that the first return light pulse signal is an interference signal, and the post-processing of the first return light pulse signal is continued.
  • a return light pulse signal is used for the above judgment.
  • FIG. 8 A specific algorithm embodiment is shown in FIG. 8 . Assuming that two laser pulse signals are emitted in step S610, the preset time interval between them is denoted as ⁇ T, and n return light pulse signals are received in step S620, wherein the TOF of the i-th return light pulse signal is denoted as T i , i ⁇ [0,n-1], then Fig. 8 shows an exemplary process of identifying valid return light pulse signals among n return light pulse signals:
  • step 810 the TOFs of n return light pulse signals are obtained, and the determination is made from the light flight time T 0 of the first return light pulse signal.
  • step 840 can be executed to judge the i-th return-light pulse signal and the j-th return light according to the optical flight time T i of the i-th return-light pulse signal and the light-of-flight time T j of the j-th return-light pulse signal Whether the pulse signal is a valid return light pulse signal.
  • the deviation between the time interval between T j and T i and the first preset time interval ⁇ T1 does not exceed the first preset threshold, then continue to judge the difference between Tj and the following Whether the deviation between the time interval between the light flight times of each return light pulse signal and the second preset time interval ⁇ T2 does not exceed the second preset threshold, and the time interval between T j and T i is the same as
  • the deviation between the first preset time interval ⁇ T1 does not exceed the first preset threshold
  • the deviation between the time interval between Tk and Tj and the second preset time interval ⁇ T2 does not exceed the second preset threshold , judging that the ith, jth and kth return light pulse signals are valid return light pulse signals, and if the jth return light pulse signal does not have the kth return light pulse signal that meets the above requirements, it is determined that the th return light pulse signal
  • the i and jth return light pulse signals are interference signals;
  • step S640 the distance between the distance measuring device and the measured object is determined according to the receiving time of the effective return light pulse signal.
  • the distance between the distance measuring device and the measured object can be determined according to the interval between the reception time of any valid return light pulse signal and the emission time of the valid return light pulse signal.
  • the distance d between the measured object and the ranging device is:
  • the distance between the distance measuring device and the measured object may be determined according to the receiving time of at least two valid return light pulse signals, and the average value of the determined at least two distances may be calculated to obtain As the final measurement result, thus improving the accuracy of the measured distance.
  • the laser ranging method 600 transmits at least two laser pulse signals continuously, and extracts an effective return light pulse signal in the return light pulse signal according to the receiving time of the return light pulse signal, thereby effectively identifying and filtering
  • the interference signal improves the robustness and anti-interference ability of the ranging device.
  • the ranging method according to the embodiment of the present invention has been exemplarily described above.
  • the distance measuring apparatus 100 provided according to the embodiment of the present invention is described below with reference to FIG. 1 again.
  • the ranging apparatus 100 according to the embodiment of the present invention may be used to implement the above-described ranging method 600 according to the embodiment of the present invention.
  • only the main structure and function of the distance measuring device 100 are described below, and some specific details that have been described above are omitted.
  • the ranging apparatus 100 includes a transmitting circuit 110 , a receiving circuit 120 , a sampling circuit 130 and an arithmetic circuit 140 .
  • the transmitting circuit 110 is used to continuously transmit at least two laser pulse signals according to a preset time interval
  • the receiving circuit 120 is used to receive the return light pulse signal
  • the sampling circuit 130 is used to determine the receiving time of the return light pulse signal
  • the arithmetic circuit 140 is used for determining, according to the receiving time, in the return light pulse signal, the effective return light pulse signal reflected by the object to be measured, and the receiving time of the valid return light pulse signal according to the at least two laser pulse signals Determine the distance between the distance measuring device and the measured object.
  • the distance measuring device 100 may further include a control circuit (not shown), which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.
  • a control circuit (not shown), which can control other circuits, for example, can control the working time of each circuit and/or set parameters for each circuit.
  • the ranging apparatus 100 further includes a control circuit 150, and the control circuit 150 is configured to modulate the preset time interval.
  • the modulation modes used to modulate the preset time interval include the following:
  • the preset time interval may be randomly generated between a preset minimum time interval and a preset maximum time interval.
  • a fixed value may be taken between a preset minimum time interval and a preset maximum time interval as the preset time interval.
  • the size of the fixed value is negatively correlated with the distance between the measured object and the distance measuring device.
  • the measured object is located within a region of interest.
  • the preset time intervals may be randomly selected from a pre-established time interval list or the preset time intervals may be selected in sequence.
  • the preset time can also be selected between a preset minimum time interval and a preset maximum time interval based on the motion state of the distance measuring device and/or the motion state of the measured object interval.
  • the size of the preset time interval is negatively correlated with the movement speed of the distance measuring device and/or the movement speed of the measured object.
  • the modulation modes include multiple types, and the control circuit 150 is further configured to select a modulation mode for modulating the time interval.
  • the modulation mode selection mode includes at least one of the following: selecting the modulation mode according to the current scene, selecting the modulation mode according to the distance between the measured object and the ranging device, selecting the modulation mode according to the The modulation mode is selected by the motion state of the object to be measured and/or the motion state of the distance measuring device, or the modulation mode is selected according to a user instruction.
  • the deviation between the time interval between the receiving times of adjacent valid return light pulse signals and the preset time interval is not greater than the preset threshold.
  • the preset threshold value is not less than the timing precision of the timer used to determine the receiving time of the return light pulse signal.
  • the preset time interval is not less than the charging and discharging time of the distance measuring device that emits the laser pulse signal.
  • the preset time interval is not greater than the difference between the sampling interval time of the ranging device and the time of flight of light corresponding to the range limit of the ranging device.
  • the effective return light pulse signals of the at least two laser pulse signals reflected back by the measured object are determined in the return light pulse signal, including:
  • first return light pulse signal is not the last return light pulse signal, then sequentially calculate the time interval between the first return light pulse signal and each return light pulse signal after the first return light pulse signal;
  • the first return light pulse signal is determined and the second return light pulse signal is an effective return light pulse signal
  • the first returning light pulse signal is determined to be interfere with the signal.
  • the number of laser pulse signals transmitted by the transmitting circuit 110 is at least three, and the preset time interval between every two adjacent laser pulse signals is the same or different.
  • the ranging device of the embodiment of the present invention continuously transmits at least two laser pulse signals, and extracts the effective return light pulse signal in the return light pulse signal according to the receiving time of the return light pulse signal, so as to effectively identify and filter the interference signal, and improve the Robustness and anti-jamming capability of ranging devices.
  • An embodiment of the present invention further provides a movable platform, the movable platform includes any of the above distance measuring devices and a movable platform body, and the distance measuring device is mounted on the movable platform body.
  • the movable platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, a camera, and a gimbal.
  • the body of the movable platform is the fuselage of the unmanned aerial vehicle.
  • the movable platform body is the body of the automobile.
  • the vehicle may be an autonomous vehicle or a semi-autonomous vehicle, which is not limited herein.
  • the movable platform body is the body of the remote control car.
  • the movable platform body is a robot.
  • the movable platform body is the camera itself.
  • the movable platform is a gimbal
  • the movable platform body is a gimbal body.
  • the gimbal can be a handheld gimbal, or a gimbal mounted on a car or an aircraft.
  • the movable platform adopts the distance measuring device according to the embodiment of the present invention, it also has the advantages mentioned above.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general purpose computer, special purpose computer, computer network, or other programmable device.
  • the computer instructions may be stored in or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be downloaded from a website site, computer, server or data center Transmission to another website site, computer, server, or data center by wire (eg, coaxial cable, optical fiber, digital subscriber line, DSL) or wireless (eg, infrared, wireless, microwave, etc.).
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that includes an integration of one or more available media.
  • the usable media may be magnetic media (eg, floppy disk, hard disk, magnetic tape), optical media (eg, digital video disc (DVD)), or semiconductor media (eg, solid state disk (SSD)), etc. .
  • the disclosed apparatus and method may be implemented in other manners.
  • the device embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components may be combined or May be integrated into another device, or some features may be omitted, or not implemented.
  • Various component embodiments of the present invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof.
  • a microprocessor or a digital signal processor (DSP) may be used in practice to implement some or all of the functions of some modules according to embodiments of the present invention.
  • DSP digital signal processor
  • the present invention may also be implemented as apparatus programs (eg, computer programs and computer program products) for performing part or all of the methods described herein.
  • Such a program implementing the present invention may be stored on a computer-readable medium, or may be in the form of one or more signals. Such signals may be downloaded from Internet sites, or provided on carrier signals, or in any other form.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

Module de télémétrie par laser, dispositif de télémétrie (100) et plateforme mobile. Le procédé consiste à : transmettre en continu au moins deux signaux d'impulsion laser selon un intervalle de temps prédéfini (S610) ; recevoir des signaux d'impulsion lumineuse de retour, et déterminer le temps de réception des signaux d'impulsion lumineuse de retour (S620) ; déterminer, dans les signaux d'impulsion lumineuse de retour selon l'intervalle de temps prédéfini et le temps de réception, des signaux d'impulsion lumineuse de retour efficaces réfléchis par lesdits deux signaux d'impulsion laser au moyen d'un objet mesuré (S630) ; et déterminer une distance entre le dispositif de télémétrie (100) et l'objet mesuré selon le temps de réception des signaux d'impulsion lumineuse de retour efficaces (S640). Lesdits deux signaux d'impulsion laser sont transmis en continu, et les signaux d'impulsion lumineuse de retour efficaces dans les signaux d'impulsion lumineuse de retour sont extraits selon le temps de réception des signaux d'impulsion lumineuse de retour, de telle sorte que des signaux de diaphonie sont efficacement reconnus et filtrés, et la robustesse et la capacité anti-interférence du dispositif de télémétrie (100) sont améliorées.
PCT/CN2020/110606 2020-08-21 2020-08-21 Module de télémétrie par laser, dispositif de télémétrie et plateforme mobile Ceased WO2022036714A1 (fr)

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CN202080013349.2A CN114391112A (zh) 2020-08-21 2020-08-21 激光测距方法、测距装置和可移动平台

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