WO2022198638A1 - 激光测距方法、激光测距装置和可移动平台 - Google Patents

激光测距方法、激光测距装置和可移动平台 Download PDF

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Publication number
WO2022198638A1
WO2022198638A1 PCT/CN2021/083287 CN2021083287W WO2022198638A1 WO 2022198638 A1 WO2022198638 A1 WO 2022198638A1 CN 2021083287 W CN2021083287 W CN 2021083287W WO 2022198638 A1 WO2022198638 A1 WO 2022198638A1
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Prior art keywords
energy characteristic
characteristic parameter
laser ranging
noise filtering
signal
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PCT/CN2021/083287
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English (en)
French (fr)
Inventor
田鹏飞
吴特思
许友
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深圳市大疆创新科技有限公司
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Priority to PCT/CN2021/083287 priority Critical patent/WO2022198638A1/zh
Publication of WO2022198638A1 publication Critical patent/WO2022198638A1/zh

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO 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
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO 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
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88Lidar systems specially adapted for specific applications
    • G01S17/93Lidar systems specially adapted for specific applications for anti-collision purposes
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO 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
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483Details of pulse systems
    • G01S7/486Receivers

Definitions

  • Embodiments of the present invention relate to the technical field of ranging, and more particularly, to a laser ranging method, a laser 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 propagation between the laser ranging device and the measured object, that is, the time-of-flight (Time-of-Flight, TOF) to detect the distance from the measured object to the laser 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.
  • the laser ranging device When the laser ranging device measures the near low reflectivity object, there will be a phenomenon of fusion of the internal reflected light and the target reflected light, and there will be errors when calculating the depth of the near low reflectivity object, which is manifested as a laser Severe brushed noise occurs between the rangefinder and the target. This kind of noise often exists in the actual use scene of the laser ranging device, which greatly restricts the performance of the laser ranging device in near measurement, and affects the perception algorithm and causes the misjudgment of obstacles.
  • the first aspect of the embodiments of the present invention provides a laser ranging method, including:
  • the fusion signal is a fusion signal of the target reflected light obtained by the laser pulse signal being reflected by the measured object and the internal reflection light of the laser ranging device;
  • the first energy characteristic parameter is compared with the noise filtering range to determine whether the fusion signal is a noise signal.
  • a second aspect of the embodiments of the present invention provides a laser ranging device, where the laser ranging device includes:
  • the transmitting circuit is used to transmit the laser pulse signal
  • the receiving circuit is used to receive the optical pulse signal
  • the fusion signal is a fusion signal of the target reflected light obtained by the laser pulse signal being reflected by the measured object and the internal reflection light of the laser ranging device;
  • the first energy characteristic parameter is compared with the noise filtering range to determine the noise signal in the fusion signal.
  • 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 laser ranging device, and the laser ranging device is mounted on the movable platform body.
  • the laser ranging method, the laser ranging device, and the movable platform according to the embodiments of the present invention identify the noise signal in the fusion signal in real time based on the relative relationship between the fusion signal and the energy characteristic parameter of the internally reflected light, and require less computation.
  • the processing result has no delay and high accuracy, which can significantly improve the reliability of the near measurement result of the laser ranging device.
  • FIG. 1 is a schematic frame diagram of a laser ranging device according to an embodiment of the present invention.
  • FIG. 2 is a schematic diagram of an embodiment in which the laser ranging device according to the embodiment of the present invention adopts a coaxial optical path;
  • FIG. 3 is a schematic diagram of a scanning pattern of a laser ranging device according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of generating a fusion signal according to an embodiment of the present invention.
  • FIG. 5 is a time domain distribution diagram of internally reflected light and target reflected light according to an embodiment of the present invention.
  • FIG. 6 is a schematic diagram of the complete fusion of internal reflected light and target reflected light according to an embodiment of the present invention
  • FIG. 7 is a schematic flowchart of a laser ranging method according to an embodiment of the present invention.
  • FIG. 8 is a diagram showing the correspondence between the internal reflection cursor and different fields of view regions according to an embodiment of the present invention.
  • the laser ranging methods provided by the various embodiments of the present invention can be applied to a laser ranging device, and the laser ranging device can be a laser radar.
  • the laser 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 laser ranging device can detect the distance from the measured object to the laser ranging device by measuring the time of light propagation between the laser ranging device and the measured object, that is, time-of-flight (TOF).
  • TOF time-of-flight
  • the laser ranging device 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 object to be measured, 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 laser ranging device 100 and the measured object based on the sampling result of the sampling circuit 130 .
  • the laser ranging 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 laser ranging 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 number of any one of the circuits, 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 may be Shooting at the same time, or shooting at different times respectively.
  • 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 laser ranging device 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
  • the distance measurement module 150 can be independent of other modules, for example, a scanning module.
  • the laser ranging device can adopt a coaxial optical path, that is, the light beam emitted by the laser ranging device and the reflected light beam share at least part of the optical path in the laser ranging device. For example, after at least one laser pulse sequence emitted by the transmitting circuit changes its propagation direction through the scanning module, the laser pulse sequence reflected by the measured object passes through the scanning module and then enters the receiving circuit.
  • FIG. 2 shows a schematic diagram of an embodiment in which the laser ranging device according to the embodiment of the present invention adopts a coaxial optical path.
  • the laser ranging device 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, and a detector 205 (which may include the above-mentioned receiving circuit, sampling circuit and arithmetic circuit) and an 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. In one embodiment, 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 test object.
  • 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 laser 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 The optical path is 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 Combine the transmit light path and the receive light path.
  • the optical path changing element can 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. In this way, in the case of using a small reflector, the occlusion of the return light by the support of the small reflector can be reduced.
  • 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 laser 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 through the collimating element 204 .
  • 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 of varying thickness 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 directions 211 and 213 , so as to scan the space around the laser ranging device 200 .
  • FIG. 3 is a schematic diagram of a scanning pattern of the laser ranging 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 measured object 201 , a part of the light is reflected by the measured object 201 to the laser ranging device 200 in a direction opposite to the projected light 211 .
  • the return light 212 reflected by the measured object 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 laser ranging device, or a filter is provided on the beam propagation path, for transmitting at least the wavelength band of the beam emitted by the transmitter. , reflecting other bands to reduce the noise that ambient light brings 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 laser ranging device 200 can use the pulse receiving time information and the pulse sending time information to calculate the TOF, so as to determine the distance from the measured object 201 to the laser ranging device 200 .
  • the distance and orientation detected by the laser ranging device 200 can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like.
  • the laser ranging device of the embodiment of the present invention can be applied to a movable platform, and the laser ranging device can be installed on the movable platform body of the movable platform.
  • the movable platform with laser ranging 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 signal chain of the laser ranging device using the coaxial optical path is shown in Figure 4.
  • the control circuit of the laser ranging device controls the transmitting circuit to emit the laser pulse signal, and the time measured by the time measurement unit at this moment is the start time Tstart; the laser pulse signal exits after passing through the optical device, and is reflected by the measured object, and then passes through the optical device.
  • the signal received by the receiving circuit and reflected back by the measured object is called the target reflected light, and the receiving time of the measured target reflected light is T1.
  • the optical devices including lenses, mirrors, prisms, window glass, etc.
  • the optical devices will also reflect the laser pulse signal, which can eventually be received by the receiving circuit and reflected by the optical device.
  • the returned signal is called internally reflected light, and the received time of the internally reflected light is measured as T0; the received target reflected light and the internally reflected light are shown in Figure 5 in the time domain.
  • the internal reflected light and the target reflected light will be too close to cause pulse fusion, see Figure 6.
  • the fusion signal will affect the identification of the receiving moment of the target reflected light. If the target reflected light is dominant in the fusion signal, the signal fusion has less influence on the discrimination of the receiving moment of the target reflected light.
  • the energy of the reflected light from the target is small, and the internal reflected light in the fusion signal dominates.
  • the depth calculation it will deviate from the actual depth value of the reflected light of the target, resulting in wire-like noise. Therefore, it is necessary to discriminate in the fusion signal in order to eliminate the noise signal in which normal depth calculation cannot be performed.
  • FIG. 7 shows a schematic flowchart of a laser ranging method 700 according to an embodiment of the present invention.
  • the laser ranging method 700 includes the following steps:
  • step S710 a laser pulse signal is emitted, and an optical pulse signal is received back;
  • step S720 determine the fusion signal in the return light pulse signal, and the fusion signal is the fusion signal of the target reflected light obtained by the laser pulse signal reflected by the measured object and the internal reflection light of the laser ranging device;
  • step S730 determine the first energy characteristic parameter of the fusion signal
  • step S740 the second energy characteristic parameter of the internally reflected light is determined, and the noise filtering intensity is determined according to the second energy characteristic parameter;
  • step S750 a noise filtering range is determined according to the second energy characteristic parameter and the noise filtering strength
  • step S760 the first energy characteristic parameter is compared with the noise filtering range to determine whether the fusion signal is a noise signal.
  • the laser ranging method 700 determines the noise filtering strength based on the second energy characteristic parameter of the internally reflected light, and then determines the noise filtering range according to the noise filtering strength and the second energy characteristic parameter, so as to determine the noise filtering range based on the fusion signal and the internal reflection
  • the relative relationship of the energy characteristic parameters of light can identify the noise signal in the fusion signal in real time, the required calculation amount is small, the processing result has no delay and high accuracy, and the reliability of the near measurement result of the laser ranging device can be significantly improved. .
  • the laser ranging method 700 may be implemented in a laser ranging device using a coaxial optical path.
  • the laser pulse signal may be transmitted by the transmitting circuit of the laser ranging device.
  • the transmitting circuit includes a laser transmitter such as a laser diode, through which a laser pulse signal of nanosecond level can be transmitted.
  • the laser pulse signal passes through the optical device and then exits into the field of view area.
  • the return light pulse signal reflected by the measured object in the field of view area passes through the optical device and then enters the receiving circuit of the laser ranging device.
  • the outgoing light and the incident light share at least part of the optical path. .
  • the internal reflected light formed by the reflection of the outgoing light inside the laser ranging device will also enter the receiving circuit.
  • the receiving circuit receives the optical signal through a photosensitive element, and converts the received optical signal into an electrical signal
  • the photosensitive element includes but is not limited to a photodiode, an avalanche photodiode or a charge coupled element. After that, 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
  • a comparator for example, an analog comparator (COMP) for converting an electrical signal into a digital pulse signal
  • 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.
  • 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
  • the return light pulse signal received by the laser ranging device not only includes the reflected light of the target reflected by the laser pulse signal by the measured object, but also includes the internal reflected light of the laser ranging device. Internally reflected light reflected back by an optical device in the optical path.
  • the main purpose of the embodiment of the present invention is to identify the noise signal in the fusion signal that will affect the time discrimination of the target reflected light, so as to eliminate the interference caused by the internal reflected light to the ranging.
  • the fusion signal in the return optical pulse signal is first determined.
  • the reason for the generation of the fusion signal is: when the measured object is close to the laser ranging device, the internal reflected light and the target reflected light are fused because they are too close in time sequence.
  • the fusion signal is screened by time, or the depth value is obtained according to the flight time of each return light pulse signal, and the fusion signal is screened according to the depth value. For example, assuming that the range of the laser ranging device is 200m, the blind area can be compressed to 5cm, and signal fusion will occur within the range of 2m. Therefore, the return light pulse signal within the range of 5cm to 2m can be determined as the fusion signal.
  • the fusion signal in the return light pulse signal may also be identified according to the waveform characteristics of the return light pulse signal, or any other suitable method may be used to identify the fusion signal in the return light pulse signal.
  • the first energy characteristic parameter of the fusion signal is determined.
  • the first energy characteristic parameter may include any parameter that can indicate the energy characteristic of the fusion signal.
  • the first energy characteristic parameter may be a parameter determined according to at least one of pulse width, height, and area of the fusion signal. Alternatively, any one of the pulse width, height, and area of the fusion signal may be directly used as the first energy characteristic parameter.
  • the energy of the fusion signal is mainly determined by the energy of the internal reflected light and the energy of the reflected light of the target.
  • the energy of the internally reflected light is constant, the greater the energy of the target reflected light, the greater the energy of the fusion signal, that is, the larger the energy characteristic parameter of the fusion signal. Therefore, the proportion of the target reflected light can be identified according to the first energy characteristic parameter of the fusion signal.
  • a second energy characteristic parameter of the internally reflected light is determined.
  • the intensity of the internal reflected light is constant, the proportion of the target reflected light is identified according to the first energy characteristic parameter of the fusion signal; but in fact, the external temperature and the oil pollution generated during the operation of the laser ranging device and so on will have an impact on the intensity of the internally reflected light, that is, the intensity of the internally reflected light will change continuously with the operation of the laser ranging device, instead of a fixed value, so it needs to be continuously during the operation of the laser ranging device.
  • the second energy characteristic parameter of the internally reflected light is adjusted to ensure the accuracy of the measurement.
  • the field of view area of the laser ranging device can be divided into multiple sub-areas.
  • the sub-area located at the center of the field of view area has a larger second energy characteristic parameter.
  • the second energy characteristic parameter of each sub-region may be determined separately.
  • the second energy characteristic parameter of the internally reflected light may be measured in real time during the operation of the laser ranging device, for example, the second energy characteristic parameter of the internally reflected light may be measured in real time every preset time . Since the time-of-flight of the internally reflected light usually varies little, the internally-reflected light in the return light pulse signal can be determined by the time of flight, and then its second energy characteristic parameter can be obtained by actual measurement; The depth parameter of the signal determines the internally reflected light in the return light pulse signal.
  • the second energy characteristic parameter of the internally reflected light in each sub-area of the field of view can be measured separately, and the second energy characteristic parameter of each sub-area The average value, the maximum value or the minimum value, etc. of the second energy characteristic parameter of each internally reflected light.
  • the second energy characteristic parameters can be measured according to the combination of motor rotation angles of the scanning module of the laser ranging device, and converted into different sub-areas according to the combination of motor rotation angles, and finally the second energy characteristics corresponding to different sub-areas are obtained. parameter. Since what is obtained in this way is the actual measurement result at the current moment or within the current time range, it is beneficial to improve the accuracy of the second energy characteristic parameter.
  • the second energy characteristic parameter may be determined according to the variation relationship of the second energy characteristic parameter with the running time.
  • the initial second energy characteristic parameter of the internally reflected light may be pre-calibrated before the laser ranging device leaves the factory, and adjusted on the basis of the calibration result of the initial second energy characteristic parameter during operation.
  • the pre-calibrated initial second energy characteristic parameter of the internally reflected light can be obtained by theoretical calculation through the characteristics of the optical device, and can also be obtained through experimental testing.
  • the motor rotation angle of the scanning module of the laser ranging device can be converted into corresponding sub-regions in the field of view region, and the initial second energy characteristic parameters of different sub-regions can be determined respectively.
  • the intensity change of the internally reflected light is affected by factors such as contamination caused by the volatilization of oil in the laser ranging device, and the reflectivity of the obstructions, the influence of these factors on the second energy characteristic parameter of the internally reflected light is also affected. It can be obtained by designing experimental tests, or it can be obtained by theoretical calculations. Generally speaking, the relationship between the second energy characteristic parameter of the internally reflected light and the operating time of the laser ranging device is that it first increases, then decreases, and finally tends to be stable.
  • the initial energy characteristic parameters of different sub-areas in the field of view are different, when calibrating the initial energy characteristic parameters, the initial energy characteristic parameters of different sub-areas can be calibrated respectively, and the parameter table corresponding to each sub-area can be obtained. , and adjust the second energy characteristic parameters of different sub-regions on this basis in the subsequent actual operation process.
  • the variation relationship of the second energy characteristic parameters of different sub-regions with the running time may be the same or different, and may be specifically obtained according to experimental tests or theoretical calculations.
  • the noise filtering strength is determined according to the second energy characteristic parameter.
  • the intensity of the internally reflected light changes, its proportion in the fusion signal will also change. For example, when the internal reflected light becomes stronger, if the intensity of the target reflected light does not change, the proportion of the internal reflected light in the fusion signal will increase, which will affect the depth calculation of the target reflected light, resulting in more changes in the subsequent point clouds. There is a lot of noise, so the filter strength needs to be increased when the internal reflection light is enhanced. Conversely, when the internally reflected light is weakened, if the intensity of the target reflected light remains unchanged, the current filtering intensity will mistakenly filter out more effective points.
  • the noise filtering strength may be determined according to the second energy characteristic parameter and the preset correspondence between different second energy characteristic parameters and different noise filtering strengths. Since the stronger the internally reflected light is, the larger its energy ratio in the fusion signal is. Therefore, the larger the second energy characteristic parameter is, the higher the corresponding noise filtering intensity is.
  • the correspondence between different second energy characteristic parameters and different noise filtering strengths can be measured experimentally or obtained through theoretical calculation.
  • the pre-calibrated initial second energy characteristic parameter and the predetermined energy determined according to the initial second energy characteristic parameter may be obtained.
  • the initial noise filtering strength then in the actual operation process, the current second energy characteristic parameter is compared with the initial second energy characteristic parameter to obtain the comparison result, and according to the comparison result, in the preset adjustable
  • the initial noise filtering strength is adjusted within the interval to obtain the current noise filtering strength, so that the current noise filtering strength matches the current second energy characteristic parameter.
  • the initial second energy characteristic parameter may be determined according to the calibration result of the initial second energy characteristic parameter before the laser ranging device leaves the factory.
  • the change of its state causes the second energy characteristic parameter to change.
  • the initial noise filtering strength is dynamically adjusted within the preset adjustable interval. For example, if the initial noise filtering strength is 1.8, and the preset adjustable range is 1.8 to 7.0, the subsequent change of the second energy characteristic parameter and the comparison result of the second energy characteristic parameter and the initial second energy characteristic parameter can be used. , and adjust the noise filter strength within the range of 1.8 to 7.0.
  • the adjustable interval and the specific adjustment range can be obtained according to experiments or obtained according to theoretical calculations.
  • the field of view area of the laser ranging device includes multiple sub-areas.
  • the noise filtering strength corresponding to the different sub-areas may be determined according to the second energy characteristic parameters corresponding to the different sub-areas, respectively. Thereby, the accuracy of the noise filtering strength is improved.
  • the correspondence between the second energy characteristic parameter and the noise filtering strength of at least two sub-regions is different, and the corresponding relationship between the second energy characteristic parameter and the noise filtering strength of different sub-regions may be calibrated in advance. In some embodiments, the same correspondence may also apply to at least two sub-regions.
  • the filtering strength is also related to depth. For example, according to the needs of the user, noise is not allowed at a relatively short distance, so the noise filtering strength is large; there may be a small amount of noise at a relatively long distance, so the noise filtering strength is small. Therefore, the depth parameter of the fusion signal can also be obtained, and the noise filtering strength can be jointly determined according to the second energy characteristic parameter and the depth parameter.
  • the noise filtering strength according to the second energy characteristic parameter and the depth parameter when determining the noise filtering strength according to the second energy characteristic parameter and the depth parameter, first determine the depth interval corresponding to the depth parameter, and then determine the correspondence between the second energy characteristic parameter and the noise filtering strength according to the depth interval, and then determine the corresponding relationship between the second energy characteristic parameter and the noise filtering strength according to the depth interval.
  • the corresponding relationship determines the noise filtering strength corresponding to the second energy characteristic parameter. That is, after the second energy characteristic parameter is determined, different corresponding relationships are applied in different depth intervals to obtain the noise filtering strength according to the second energy characteristic parameter.
  • the noise filtering strength can be set in three or more depth intervals, and the boundary values of different depth intervals can be monitored and obtained through an aging test process before leaving the factory, and written into the firmware.
  • the above-mentioned depth interval can also be set by the user, so that the noise filtering strategy can better meet the needs of the user. For example, if the user requires that more noise points are not allowed within 0.5m, the boundary value of the depth interval can be set to 0.5m; specifically, a user interface can be provided, and the first user instruction to adjust the range of the depth interval can be received through the user interface. , and adjust the range of the depth interval according to the first user instruction.
  • the second energy characteristic parameter of different depth intervals and the noise filtering intensity are adjusted.
  • the corresponding relationship of noise intensity can be adjusted. For example, for the depth range within 0.5m, if the user thinks that the current noise filtering strength still cannot meet the requirements, the gear of the noise filtering strength can be adjusted so that the same second energy characteristic parameter within 0.5m can be mapped to a larger filter strength.
  • step S750 the noise filtering range is determined according to the second energy characteristic parameter and the noise filtering strength; and in step S760, the first energy characteristic parameter is compared with the noise filtering range to identify the noise signal in the fusion signal.
  • the first energy characteristic parameter is not higher than the noise filtering range, it indicates that the target reflected light is not dominant in the fusion signal, so the corresponding fusion signal is determined as a noise signal.
  • the noise filtering range may be the product of the second energy characteristic parameter and the noise filtering strength, that is, the noise filtering strength represents a coefficient; however, the noise filtering range is not limited thereto, for example, the noise filtering strength may also represent an index.
  • the depth value is calculated based on the fusion signal, a large error will occur. , so it can be judged that the fusion signal is a noise signal at this time.
  • the noise filtering range can be expressed as N ⁇ A2; if A1>N ⁇ A2, the corresponding fusion The signal is determined as a valid signal, and if A1 ⁇ N ⁇ A2, the corresponding fusion signal is determined as a noise signal.
  • the above judgment process can also be expressed as: if the ratio of the second energy characteristic parameter to the first energy characteristic parameter is not higher than the noise filtering strength, then the corresponding fusion signal is determined as a noise signal, that is, if A1/A2> N, the corresponding fusion signal is determined as a valid signal, and if A1/A2 ⁇ N, the corresponding fusion signal is determined as a noise signal.
  • the noise signal may be filtered out.
  • point cloud data can be generated according to the return light pulse signal after filtering out the noise signal, and the point cloud data can be output to the upper-layer computing platform. Therefore, the noise signal is directly filtered at the bottom layer, which avoids the consumption of computing resources and the problem of delay caused by the noise filtering performed by the upper-layer computing platform.
  • the noise signal may also be marked, and the upper-layer computing platform decides to filter the noise signal or perform other analysis as required.
  • the laser ranging device can generate point cloud data according to the return light pulse signal, and add abnormal point marks to the point cloud points in the point cloud data corresponding to the noise signal. After that, the laser ranging device can output point cloud data to the upper-layer computing platform.
  • the upper-layer computing platform can directly identify the point cloud points caused by noise signals, and quickly remove them when noise filtering is required. Part of the point cloud point without adding extra computation to identify the noise.
  • the laser ranging method 700 determines the noise filtering intensity based on the energy characteristic parameter of the internally reflected light, and then determines the noise filter for the fusion signal according to the energy characteristic parameter and the filtering noise intensity of the internally reflected light. Therefore, based on the relative relationship between the fusion signal and the energy characteristic parameters of the internal reflected light, the noise signal in the fusion signal can be identified in real time. The reliability of the near measurement results of the laser ranging device can be significantly improved.
  • the ranging method according to the embodiment of the present invention has been exemplarily described above.
  • the laser ranging device 100 provided according to the embodiment of the present invention is described below with reference to FIG. 1 again.
  • the laser ranging apparatus 100 according to the embodiment of the present invention may be used to implement the laser ranging method 700 according to the embodiment of the present invention described above.
  • only the main structure and function of the laser ranging device 100 are described below, and some specific details that have been described above are omitted.
  • the laser ranging device 100 includes a transmitting circuit 110 , a receiving circuit 120 and an arithmetic circuit 140 .
  • the transmitting circuit 110 is used for transmitting a laser pulse signal
  • the receiving circuit 120 is used for receiving the returning light pulse signal
  • the arithmetic circuit 140 is used for: determining a fusion signal in the returning light pulse signal, and the fusion signal is the laser pulse a fusion signal of the target reflected light obtained by the signal being reflected by the measured object and the internal reflected light of the laser ranging device; determine the first energy characteristic parameter of the fusion signal; determine the second energy characteristic parameter of the internally reflected light, and determine the noise filtering strength according to the second energy characteristic parameter; determine the noise filtering range according to the second energy characteristic parameter and the noise filtering strength; compare the first energy characteristic parameter with the noise filtering range , to determine whether the fusion signal is a noise signal.
  • the laser ranging device 100 may further include a sampling circuit 130 and a control circuit 150 .
  • the comparing the first energy characteristic parameter with the noise filtering range to determine the noise signal in the fusion signal includes:
  • the fusion signal is a noise signal.
  • the noise filtering range includes the product of the second energy characteristic parameter and the noise filtering strength.
  • the determining the second energy characteristic parameter of the internally reflected light includes: measuring the second energy characteristic parameter of the internally reflected light in real time; or, according to the change of the second energy characteristic parameter with the running time The relationship determines the second energy characteristic parameter.
  • the determining the noise filtering strength according to the second energy characteristic parameter includes: according to the second energy characteristic parameter, and the difference between different preset second energy characteristic parameters and different noise filtering strengths The corresponding relationship is used to determine the noise filtering strength.
  • the determining the noise filtering strength according to the second energy characteristic parameter and the preset correspondence between different second energy characteristic parameters and different noise filtering strengths includes: acquiring a pre-calibrated The initial second energy characteristic parameter of , and the initial noise filtering strength determined according to the initial second energy characteristic parameter; compare the current second energy characteristic parameter with the initial second energy characteristic parameter to obtain Comparison result; according to the comparison result, adjust the initial noise filtering strength within a preset adjustable interval to obtain the current noise filtering strength.
  • the field of view area of the laser ranging device includes a plurality of sub-areas
  • the determining the noise filtering strength according to the second energy characteristic parameter includes: according to the second energy corresponding to different sub-areas respectively
  • the characteristic parameters are used to determine the noise filtering strengths corresponding to different sub-regions.
  • the corresponding relationship between the second energy characteristic parameter and the noise filtering strength of at least two sub-regions is different.
  • the method further includes: acquiring a depth parameter of the return light pulse signal; and determining the noise filtering intensity at the current moment according to the second energy characteristic parameter, comprising: according to the second energy characteristic The parameter and the depth parameter determine the noise filtering strength.
  • the determining the noise filtering strength according to the second energy characteristic parameter and the depth parameter includes: determining a depth interval corresponding to the depth parameter; determining the first depth interval according to the depth interval.
  • the corresponding relationship between the second energy characteristic parameter and the noise filtering intensity, and the noise filtering intensity corresponding to the second energy characteristic parameter is determined according to the corresponding relationship.
  • the laser ranging device further includes a user interface, configured to receive a first user instruction for adjusting the range of the depth interval; the arithmetic circuit is further configured to adjust the The range of the depth interval can be adjusted.
  • the laser ranging device further includes a user interface for receiving a second user instruction for adjusting the corresponding relationship between the second energy characteristic parameter in different depth intervals and the noise filtering strength; the computing The circuit is further configured to adjust the corresponding relationship between the second energy characteristic parameter and the noise filtering strength in different depth intervals according to the second user instruction.
  • the operation circuit is further configured to: generate point cloud data according to the return light pulse signal; add an abnormal point mark to the point cloud point corresponding to the noise signal in the point cloud data; point cloud data.
  • the operation circuit is further configured to: filter out the noise signal.
  • the laser ranging device is a laser ranging device using a coaxial optical path.
  • the laser ranging device identifies the noise signal in the fusion signal in real time based on the relative relationship between the fusion signal and the energy characteristic parameters of the internally reflected light, requires less computation, and has no delay in processing results and high accuracy , which can significantly improve the reliability of the near measurement results of the laser ranging device.
  • An embodiment of the present invention further provides a movable platform, the movable platform includes any one of the above-mentioned laser ranging devices and a movable platform body, and the laser ranging 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 driving vehicle or a semi-autonomous driving 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 movable platform adopts the laser ranging 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 the 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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Abstract

一种激光测距方法、激光测距装置和可移动平台,该方法包括:发射激光脉冲信号,并接收回光脉冲信号(S710);确定回光脉冲信号中的融合信号,融合信号为激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号(S720);确定融合信号的第一能量特征参数(S730);确定内部反射光的第二能量特征参数,并根据第二能量特征参数确定滤噪强度(S740);根据第二能量特征参数和滤噪强度确定滤噪范围(S750);将第一能量特征参数与滤噪范围进行比对,以确定融合信号是否为噪声信号(S760)。该方法和装置根据信号的能量特征参数识别出融合信号中的噪声信号,提高了激光测距装置的可靠性。

Description

激光测距方法、激光测距装置和可移动平台 技术领域
本发明实施例涉及测距技术领域,并且更具体地,涉及一种激光测距方法、激光测距装置和可移动平台。
背景技术
诸如激光雷达在内的三维点云探测系统、激光测距仪等激光测距装置可以通过测量激光测距装置和被测物之间光传播的时间,即光飞行时间(Time-of-Flight,TOF),来探测被测物到激光测距装置的距离。此类激光测距装置由发射端发射出一束激光脉冲,经被测物反射,接收端接收被测物的反射信号,形成接收脉冲,通过测量发射脉冲和接收脉冲之间的时间间隔,从而计算激光测距装置与被测物之间的距离。
激光测距装置在对近处低反射率物体进行测量时,会存在内部反射光和目标反射光二者发生融合的现象,在解算近处低反射率物体的深度时会出现误差,表现为激光测距装置与目标物之间会出现严重的拉丝状的噪点。这种噪点在激光测距装置的实际使用场景中经常存在,极大地制约了激光测距装置在近处测量的性能,影响感知算法造成障碍物的误判。
发明内容
在发明内容部分中引入了一系列简化形式的概念,这将在具体实施方式部分中进一步详细说明。本发明的发明内容部分并不意味着要试图限定出所要求保护的技术方案的关键特征和必要技术特征,更不意味着试图确定所要求保护的技术方案的保护范围。
针对现有技术的不足,本发明实施例第一方面提供了一种激光测距方法,包括:
发射激光脉冲信号,并接收回光脉冲信号;
确定所述回光脉冲信号中的融合信号,所述融合信号为所述激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号;
确定所述融合信号的第一能量特征参数;
确定所述内部反射光的第二能量特征参数,并根据所述第二能量特征参数确定滤噪强度;
根据所述第二能量特征参数和所述滤噪强度确定滤噪范围;
将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号是否为噪声信号。
本发明实施例第二方面提供了一种激光测距装置,所述激光测距装置包括:
发射电路,用于发射激光脉冲信号;
接收电路,用于接收回光脉冲信号;
运算电路,用于:
确定所述回光脉冲信号中的融合信号,所述融合信号为所述激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号;
确定所述融合信号的第一能量特征参数;
确定所述内部反射光的第二能量特征参数,并根据所述第二能量特征参数确定滤噪强度;
根据所述第二能量特征参数和所述滤噪强度确定滤噪范围;
将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号中的噪声信号。
本发明实施例第三方面提供一种可移动平台,所述可移动平台包括可移动平台本体和上述激光测距装置,所述激光测距装置搭载于所述可移动平台本体上。
本发明实施例的激光测距方法、激光测距装置和可移动平台基于融合信号与内部反射光的能量特征参数的相对关系实时地识别出融合信号中的噪声信号,所需的运算量少,处理结果无延时且准确度高,能够显著提升激光测距装置近处测量结果的可靠性。
附图说明
为了更清楚地说明本发明实施例的技术方案,下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图仅仅是本发明的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动 性的前提下,还可以根据这些附图获得其他的附图。
图1是本发明实施例所涉及的一种激光测距装置的示意性框架图;
图2是本发明实施例所涉及的激光测距装置采用同轴光路的一种实施例的示意图;
图3是根据本发明实施例的激光测距装置的一种扫描图案的示意图;
图4是根据本发明实施例的产生融合信号的原理图;
图5是根据本发明实施例的内部反射光和目标反射光的时域分布图;
图6是根据本发明实施例的内部反射光和目标反射光完全融合的示意图;
图7是根据本发明实施例的激光测距方法的示意性流程图;
图8是根据本发明实施例的内部反射光标定与不同视场区域之间的对应关系图。
具体实施方式
为了使得本发明的目的、技术方案和优点更为明显,下面将参照附图详细描述根据本发明的示例实施例。显然,所描述的实施例仅仅是本发明的一部分实施例,而不是本发明的全部实施例,应理解,本发明不受这里描述的示例实施例的限制。基于本发明中描述的本发明实施例,本领域技术人员在没有付出创造性劳动的情况下所得到的所有其它实施例都应落入本发明的保护范围之内。
在下文的描述中,给出了大量具体的细节以便提供对本发明更为彻底的理解。然而,对于本领域技术人员而言显而易见的是,本发明可以无需一个或多个这些细节而得以实施。在其他的例子中,为了避免与本发明发生混淆,对于本领域公知的一些技术特征未进行描述。
应当理解的是,本发明能够以不同形式实施,而不应当解释为局限于这里提出的实施例。相反地,提供这些实施例将使公开彻底和完全,并且将本发明的范围完全地传递给本领域技术人员。
在此使用的术语的目的仅在于描述具体实施例并且不作为本发明的限制。在此使用时,单数形式的“一”、“一个”和“所述/该”也意图包括复数形式,除非上下文清楚指出另外的方式。还应明白术语“组成”和/或“包括”,当在该说明书中使用时,确定所述特征、整数、步骤、操作、元件和/或部件的存 在,但不排除一个或更多其它的特征、整数、步骤、操作、元件、部件和/或组的存在或添加。在此使用时,术语“和/或”包括相关所列项目的任何及所有组合。
为了彻底理解本发明,将在下列的描述中提出详细的结构,以便阐释本发明提出的技术方案。本发明的可选实施例详细描述如下,然而除了这些详细描述外,本发明还可以具有其他实施方式。
本发明各个实施例提供的激光测距方法可以应用于激光测距装置,该激光测距装置可以是激光雷达。在一种实施方式中,激光测距装置用于感测外部环境信息,例如,环境目标的距离信息、方位信息、反射强度信息、速度信息等。激光测距装置可以通过测量激光测距装置和被测物之间光传播的时间,即光飞行时间(Time-of-Flight,TOF),来探测被测物到激光测距装置的距离。
为了便于理解,以下将结合图1所示的激光测距装置100对测距的工作流程进行举例描述。
如图1所示,激光测距装置100可以包括发射电路110、接收电路120、采样电路130和运算电路140。
发射电路110可以发射光脉冲序列(例如激光脉冲序列)。接收电路120可以接收经过被被测物反射的光脉冲序列,并对该光脉冲序列进行光电转换,以得到电信号,再对电信号进行处理之后可以输出给采样电路130。采样电路130可以对电信号进行采样,以获取采样结果。运算电路140可以基于采样电路130的采样结果,以确定激光测距装置100与被被测物之间的距离。
可选地,该激光测距装置100还可以包括控制电路150,该控制电路150可以实现对其他电路的控制,例如,可以控制各个电路的工作时间和/或对各个电路进行参数设置等。
应理解,虽然图1示出的激光测距装置中包括一个发射电路、一个接收电路、一个采样电路和一个运算电路,用于出射一路光束进行探测,但是本申请实施例并不限于此,发射电路、接收电路、采样电路、运算电路中的任一种电路的数量也可以是至少两个,用于沿相同方向或分别沿不同方向出射至少两路光束;其中,该至少两束光路可以是同时出射,也可以是分别在不同时刻出射。一个示例中,该至少两个发射电路中的发光芯片封装在同一个模块中。例如,每个发射电路包括一个激光发射芯片,该至少两个发射电路中的激光发射芯片 中的die封装到一起,容置在同一个封装空间中。
一些实现方式中,除了图1所示的电路,激光测距装置100还可以包括扫描模块,用于将发射电路出射的至少一路激光脉冲序列改变传播方向出射。
其中,可以将包括发射电路110、接收电路120、采样电路130和运算电路140的模块,或者,包括发射电路110、接收电路120、采样电路130、运算电路140和控制电路150的模块称为测距模块,该测距模块150可以独立于其他模块,例如,扫描模块。
激光测距装置可以采用同轴光路,也即激光测距装置出射的光束和经反射回来的光束在激光测距装置内共用至少部分光路。例如,发射电路出射的至少一路激光脉冲序列经扫描模块改变传播方向出射后,经被测物反射回来的激光脉冲序列经过扫描模块后入射至接收电路。图2示出了本发明实施例的激光测距装置采用同轴光路的一种实施例的示意图。
如图2所示,激光测距装置200包括测距模块210,测距模块210包括发射器203(可以包括上述的发射电路)、准直元件204、探测器205(可以包括上述的接收电路、采样电路和运算电路)和光路改变元件206。测距模块210用于发射光束,且接收回光,将回光转换为电信号。其中,发射器203可以用于发射光脉冲序列。在一个实施例中,发射器203可以发射激光脉冲序列。可选的,发射器203发射出的激光束为波长在可见光范围之外的窄带宽光束。准直元件204设置于发射器的出射光路上,用于准直从发射器203发出的光束,将发射器203发出的光束准直为平行光出射至扫描模块。准直元件还用于会聚经被测物反射的回光的至少一部分。该准直元件204可以是准直透镜或者是其他能够准直光束的元件。
在图2所示实施例中,通过光路改变元件206来将激光测距装置内的发射光路和接收光路在准直元件204之前合并,使得发射光路和接收光路可以共用同一个准直元件,使得光路更加紧凑。在其他的一些实现方式中,也可以是发射器203和探测器205分别使用各自的准直元件,将光路改变元件206设置在准直元件之后的光路上。
在图2所示实施例中,由于发射器203出射的光束的光束孔径较小,激光测距装置所接收到的回光的光束孔径较大,所以光路改变元件可以采用小面积的反射镜来将发射光路和接收光路合并。在其他的一些实现方式中,光路改 变元件也可以采用带通孔的反射镜,其中该通孔用于透射发射器203的出射光,反射镜用于将回光反射至探测器205。这样可以减小采用小反射镜的情况中小反射镜的支架会对回光的遮挡。
在图2所示实施例中,光路改变元件偏离了准直元件204的光轴。在其他的一些实现方式中,光路改变元件也可以位于准直元件204的光轴上。
激光测距装置200还包括扫描模块202。扫描模块202放置于测距模块210的出射光路上,扫描模块202用于改变经准直元件204出射的准直光束219的传输方向并投射至外界环境,并将回光投射至准直元件204。回光经准直元件204汇聚到探测器205上。
在一个实施例中,扫描模块202可以包括至少一个光学元件,用于改变光束的传播路径,其中,该光学元件可以通过对光束进行反射、折射、衍射等等方式来改变光束传播路径。例如,扫描模块202包括透镜、反射镜、棱镜、光栅、液晶、光学相控阵(Optical Phased Array)或上述光学元件的任意组合。一个示例中,至少部分光学元件是运动的,例如通过驱动模块来驱动该至少部分光学元件进行运动,该运动的光学元件可以在不同时刻将光束反射、折射或衍射至不同的方向。在一些实施例中,扫描模块202的多个光学元件可以绕共同的轴209旋转或振动,每个旋转或振动的光学元件用于不断改变入射光束的传播方向。在一个实施例中,扫描模块202的多个光学元件可以以不同的转速旋转,或以不同的速度振动。在另一个实施例中,扫描模块202的至少部分光学元件可以以基本相同的转速旋转。在一些实施例中,扫描模块的多个光学元件也可以是绕不同的轴旋转。在一些实施例中,扫描模块的多个光学元件也可以是以相同的方向旋转,或以不同的方向旋转;或者沿相同的方向振动,或者沿不同的方向振动,在此不作限制。
在一个实施例中,扫描模块202包括第一光学元件214和与第一光学元件214连接的驱动器216,驱动器216用于驱动第一光学元件214绕转动轴209转动,使第一光学元件214改变准直光束219的方向。第一光学元件214将准直光束219投射至不同的方向。在一个实施例中,准直光束219经第一光学元件改变后的方向与转动轴209的夹角随着第一光学元件214的转动而变化。在一个实施例中,第一光学元件214包括相对的非平行的一对表面,准直光束219穿过该对表面。在一个实施例中,第一光学元件214包括厚度沿至少一个 径向变化的棱镜。在一个实施例中,第一光学元件214包括楔角棱镜,对准直光束219进行折射。
在一个实施例中,扫描模块202还包括第二光学元件215,第二光学元件215绕转动轴209转动,第二光学元件215的转动速度与第一光学元件214的转动速度不同。第二光学元件215用于改变第一光学元件214投射的光束的方向。在一个实施例中,第二光学元件215与另一驱动器217连接,驱动器217驱动第二光学元件215转动。第一光学元件214和第二光学元件215可以由相同或不同的驱动器驱动,使第一光学元件214和第二光学元件215的转速和/或转向不同,从而将准直光束219投射至外界空间不同的方向,可以扫描较大的空间范围。在一个实施例中,控制器218控制驱动器216和217,分别驱动第一光学元件214和第二光学元件215。第一光学元件214和第二光学元件215的转速可以根据实际应用中预期扫描的区域和样式确定。驱动器216和217可以包括电机或其他驱动器。
在一个实施例中,第二光学元件215包括相对的非平行的一对表面,光束穿过该对表面。在一个实施例中,第二光学元件215包括厚度沿至少一个径向变化的棱镜。在一个实施例中,第二光学元件215包括楔角棱镜。
一个实施例中,扫描模块202还包括第三光学元件(图未示)和用于驱动第三光学元件运动的驱动器。可选地,该第三光学元件包括相对的非平行的一对表面,光束穿过该对表面。在一个实施例中,第三光学元件包括厚度沿至少一个径向变化的棱镜。在一个实施例中,第三光学元件包括楔角棱镜。第一、第二和第三光学元件中的至少两个光学元件以不同的转速和/或转向转动。
扫描模块202中的各光学元件旋转可以将光投射至不同的方向,例如方向211和213,如此对激光测距装置200周围的空间进行扫描。如图3所示,图3为激光测距装置200的一种扫描图案的示意图。可以理解的是,扫描模块内的光学元件的速度变化时,扫描图案也会随之变化。
当扫描模块202投射出的光211打到被测物201时,一部分光被被测物201沿与投射的光211相反的方向反射至激光测距装置200。被测物201反射的回光212经过扫描模块202后入射至准直元件204。
探测器205与发射器203放置于准直元件204的同一侧,探测器205用于将穿过准直元件204的至少部分回光转换为电信号。
一个实施例中,各光学元件上镀有增透膜。可选的,增透膜的厚度与发射器203发射出的光束的波长相等或接近,能够增加透射光束的强度。
一个实施例中,激光测距装置中位于光束传播路径上的一个元件表面上镀有滤光层,或者在光束传播路径上设置有滤光器,用于至少透射发射器所出射的光束所在波段,反射其他波段,以减少环境光给接收器带来的噪音。
在一些实施例中,发射器203可以包括激光二极管,通过激光二极管发射纳秒级别的激光脉冲。进一步地,可以确定激光脉冲接收时间,例如,通过探测电信号脉冲的上升沿时间和/或下降沿时间确定激光脉冲接收时间。如此,激光测距装置200可以利用脉冲接收时间信息和脉冲发出时间信息计算TOF,从而确定被测物201到激光测距装置200的距离。
激光测距装置200探测到的距离和方位可以用于遥感、避障、测绘、建模、导航等。在一种实施方式中,本发明实施方式的激光测距装置可应用于可移动平台,激光测距装置可安装在可移动平台的可移动平台本体。具有激光测距装置的可移动平台可对外部环境进行测量,例如,测量可移动平台与障碍物的距离用于避障等用途,和对外部环境进行二维或三维的测绘。在某些实施方式中,可移动平台包括无人飞行器、汽车、遥控车、机器人、相机中的至少一种。
采用同轴光路的激光测距装置的信号链路如图4所示。激光测距装置的控制电路控制发射电路发射激光脉冲信号,此刻时间测量单元测量到的时间为起始时间Tstart;激光脉冲信号经过光学器件后出射,经被测物反射后,再经光学器件由接收电路接收,由被测物反射回的信号称为目标反射光,测量得到目标反射光的接收时间为T1。但同时,由于使用同轴光路,激光测距装置自身的光学器件(包括透镜、反射镜、棱镜、窗口玻璃等)也会反射激光脉冲信号,最终也可以由接收电路接收到,由光学器件反射回的信号称为内部反射光,测量得到内部反射光的接收时间为T0;接收到的目标反射光和内部反射光在时域上如图5所示。
当被测物距离激光测距装置较近时,内部反射光和目标反射光会由于过于接近而出现脉冲融合,参见图6。融合信号会影响对目标反射光的接收时刻的鉴别。若在融合信号中目标反射光占据主导,则信号融合对目标反射光接收时刻的鉴别影响较小。但当测量近处低反射率物体时,目标反射光的能量较小,融合信号中内部反射光占据主导,当进行深度计算时会偏离目标反射光的实际 深度值,从而产生拉丝状的噪点。因此,需要在融合信号中进行鉴别,以便剔除其中无法进行正常深度计算的噪声信号。
如果在上层运算平台采用图像识别或空间滤波的方法去掉拉丝噪点,则需要大量的点云数据进行运算,不仅消耗运算资源,同时计算结果存在一定的延时。
基于此,本发明实施例提出了一种激光测距方法,用于解决激光测距技术中存在的上述问题。图7示出了根据本发明实施例的激光测距方法700的示意性流程图。如图7所示,激光测距方法700包括以下步骤:
在步骤S710,发射激光脉冲信号,并接收回光脉冲信号;
在步骤S720,确定所述回光脉冲信号中的融合信号,所述融合信号为所述激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号;
在步骤S730,确定所述融合信号的第一能量特征参数;
在步骤S740,确定所述内部反射光的第二能量特征参数,并根据所述第二能量特征参数确定滤噪强度;
在步骤S750,根据所述第二能量特征参数和所述滤噪强度确定滤噪范围;
在步骤S760,将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号是否为噪声信号。
本发明实施例的激光测距方法700以内部反射光的第二能量特征参数为依据确定滤噪强度,进而根据滤噪强度和第二能量特征参数确定滤噪范围,从而基于融合信号与内部反射光的能量特征参数的相对关系实时地识别出融合信号中的噪声信号,所需的运算量少,处理结果无延时且准确度高,能够显著提升激光测距装置近处测量结果的可靠性。
本发明实施例的激光测距方法700可以实现于采用同轴光路的激光测距装置中,具体可以参照图1和图2对激光测距装置的描述。步骤S710中,激光脉冲信号可以由激光测距装置的发射电路发射。发射电路包括例如激光二极管的激光发射器,通过激光二极管可以发射纳秒级别的激光脉冲信号。激光脉冲信号经过光学器件后出射到视场区域,视场区域内的被测物反射的回光脉冲信号经过光学器件后入射到激光测距装置的接收电路,出射光和入射光共用至少部分光路。除了被测物反射的目标反射光以外,出射光在激光测距装置内部 发生反射所形成的内部反射光也将入射到接收电路。接收电路通过感光元件接收光学信号,并将接收到的光学信号转化为电信号,感光元件包括但不限于光电二极管、雪崩光电二极管或电荷耦合元件。之后,感光元件将电信号送入一级或二级放大电路进行放大,并将放大后的电信号送入采样电路。作为一种实现方式,采样电路包括比较器(例如,可以为模拟比较器(analog comparator,COMP),用于将电信号转换为数字脉冲信号)和时间测量电路,经由一级或二级放大电路放大后的电信号经所述比较器后进入时间测量电路,由时间测量电路进行次数统计。
其中,时间测量电路可以是时间数字转换器(Time-to-Data Converter,TDC)时。其中TDC可以是独立的TDC芯片,或者是基于现场可编程门阵列(Field-Programmable Gate Array,FPGA)或特定应用集成电路(Application Specific Integrated Circuit,ASIC)或复杂可编程逻辑器件(Complex Programmable Logic Device,CPLD等可编程器件的内部延时链来实现时间测量的TDC电路,或者,采用高频时钟实现时间测量的电路结构或者计数方式实现时间测量的电路结构。
示例性地,比较器的第一输入端用于接收从放大电路输入的电信号,该电信号可以是电压信号或电流信号;比较器的第二输入端用于接收预设阈值,输入到比较器的电信号与预设阈值进行比较运算。比较器的输出信号接TDC,TDC可以测量比较器输出信号沿的时间信息,所测量时间是以光脉冲信号的发射时间作为参考,也就是可以测量到激光脉冲信号从发射到接收之间的时间差。
作为另一种实现方式,采样模块也可以包括模数转换器(Analog-to-Digital Converter,ADC)。输入到采样模块的模拟信号经过ADC的模数转换之后,可以输出数字信号至运算模块。
如上所述,在接收阶段,激光测距装置接收到的回光脉冲信号不止包括激光脉冲信号经被测物反射回的目标反射光,还包括激光测距装置的内部反射光,例如采用同轴光路时光学器件反射回的内部反射光。本发明实施例的主要目的在于识别出融合信号中会对目标反射光的时间鉴别产生影响的噪声信号,从而排除内部反射光对测距造成的干扰。
具体地,在步骤S720中,首先确定回光脉冲信号中的融合信号。由于融 合信号的产生原因为:当被测物距离激光测距装置较近时,内部反射光与目标反射光由于过于时序上过于接近而发生融合,因此,可以根据每一个回光脉冲信号的飞行时间筛选其中的融合信号,或者根据每一个回光脉冲信号的飞行时间得到深度值,并根据深度值筛选其中的融合信号。例如,假设激光测距装置的量程为200m,盲区可压缩至5cm,2m范围内会发生信号融合,因此,可以将5cm至2m范围内的回光脉冲信号确定为融合信号。
可选地,在其他实施例中,也可以根据回光脉冲信号的波形特征识别其中的融合信号,或采用其他任何合适的方法识别回光脉冲信号中的融合信号。
在识别到融合信号之后,在步骤S730中,确定融合信号的第一能量特征参数。其中,第一能量特征参数可以包括任何能够指示融合信号的能量特征的参数。例如,第一能量特征参数可以是根据融合信号的脉宽、高度、面积中的至少一种确定的参数。或者,也可以直接采用融合信号的脉宽、高度、面积中的任意一种作为第一能量特征参数。
融合信号的能量大小主要由内部反射光的能量和目标反射光的能量两部分来决定,对于目标反射光来说,其能量大小与被测物的反射率正相关,与被测物的距离负相关。当内部反射光的能量大小一定时,目标反射光的能量越大,则融合信号的能量越大,即融合信号的能量特征参数越大。因此,可以根据融合信号的第一能量特征参数识别出其中目标反射光所占的比例。
在步骤S740中,确定内部反射光的第二能量特征参数。如上所述,如果内部反射光的强度一定,则根据融合信号的第一能量特征参数识别出其中目标反射光所占的比例;但事实上,外界温度和激光测距装置运行过程中产生的油污等都会对内部反射光的强度产生影响,即内部反射光的强度会随着激光测距装置的运行不断变化,而不再是某个固定值,因而需要在激光测距装置的运行过程中不断对内部反射光的第二能量特征参数进行调整,以保证测量的准确性。
由于激光测距装置的光学特性,对应于激光测距装置视场区域不同位置的内部反射光的强度不同。因此,如图8所示,可以将激光测距装置的视场区域划分为多个子区域,一般来说,位于视场区域中心位置的子区域具有较大的第二能量特征参数。在确定内部反射光的第二能量特征参数时,可以分别确定每个子区域的第二能量特征参数。
在一个实施例中,可以在激光测距装置的运行过程中实时测量内部反射光 的第二能量特征参数,例如,可以每隔预设时间对内部反射光的第二能量特征参数进行一次实时测量。由于内部反射光的飞行时间通常变化较小,因而可以通过飞行时间确定回光脉冲信号中的内部反射光,进而通过实际测量得到其第二能量特征参数;或者,也可以根据每个回光脉冲信号的深度参数确定回光脉冲信号中的内部反射光。在对第二能量特征参数进行实时测量的过程中,可以分别测量视场区域每个子区域的内部反射光的第二能量特征参数,每个子区域的第二能量特征参数可以是该子区域内多个内部反射光的第二能量特征参数的平均值、最大值或最小值等。在测量过程中,可以根据激光测距装置扫描模块的电机旋转角度组合对第二能量特征参数进行测量,并根据电机旋转角度组合换算为不同子区域,最终得到不同子区域对应的第二能量特征参数。由于这种方式获得的是当前时刻或当前时间范围内的实际测量结果,因而有利于提高第二能量特征参数的准确性。
在另一个实施例中,可以根据第二能量特征参数随运行时间的变化关系确定第二能量特征参数。示例性地,可以在激光测距装置出厂前预先对内部反射光的初始第二能量特征参数进行标定,并在运行过程中在初始第二能量特征参数的标定结果的基础上进行调整。预先标定的内部反射光的初始第二能量特征参数可以通过光学器件的特性由理论计算获得,也可通过实验测试获得。具体地,可以根据激光测距装置扫描模块的电机旋转角度换算到视场区域中对应的子区域,并分别确定不同子区域的初始第二能量特征参数。除此之外,由于内部反射光的强度变化受到激光测距装置内部油污挥发引起的脏污、遮挡物的反射率等因素的影响,这些因素对内部反射光的第二能量特征参数的影响也可以通过设计实验测试获得,或可以通过理论计算获得。一般来说,内部反射光的第二能量特征参数随激光测距装置运行时间的变化关系为先变大、之后变小,最后趋于稳定。
由于视场区域中不同子区域的第二能量特征参数不同,因此在对初始能量特征参数进行标定时,可以分别对不同子区域的初始能量特征参数进行标定,得到与每个子区域对应的参数表,并在后续实际运行过程中在此基础上分别对不同子区域的第二能量特征参数进行调整。不同子区域的第二能量特征参数随运行时间的变化关系可以相同,也可以不同,具体可以根据实验测试或理论计算获得。
在确定第二能量特征参数之后,根据第二能量特征参数确定滤噪强度。当内部反射光的强度发生变化时,其在融合信号中所占的比例也将发生变化。例如,内部反射光变强时,若目标反射光的强度不变,则内部反射光在融合信号中所占的比例增大,从而影响目标反射光的深度计算,导致后续的点云中出现更多噪点,因此,当内部反射光增强时需要提高滤噪强度。反之当内部反射光减弱时,若目标反射光的强度不变,则采用当前的滤噪强度会误滤除较多有效点,因此,当内部反射光减弱时,需要降低滤噪强度。因此,根据目标反射光的第二能量特征参数动态调整滤噪强度对避免因滤噪强度过大而过度滤除、以及滤噪强度过小而遗留噪点所导致的使用问题至关重要。
具体地,可以根据第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定滤噪强度。由于内部反射光越强,其在融合信号中的能量比例越大,因此,第二能量特征参数越大,则与之对应的滤噪强度越高。不同第二能量特征参数与不同滤噪强度之间的对应关系可以根据实验测得,也可以通过理论计算得到。
在一个实施例中,当在初始第二能量特征参数的基础上进行调节从而得到第二能量特征参数时,可以获取预先标定的初始第二能量特征参数、以及根据初始第二能量特征参数确定的初始滤噪强度;之后在实际运行过程中,将当前的第二能量特征参数与初始第二能量特征参数进行比对,以得到比对结果,并根据该比对结果,在预先设置的可调区间内对初始滤噪强度进行调节,以得到当前的滤噪强度,使得当前的滤噪强度与当前的第二能量特征参数相匹配。
例如,初始第二能量特征参数可以是激光测距装置出厂前根据初始第二能量特征参数的标定结果而确定的,在激光测距装置运行过程中,其状态变化导致第二能量特征参数发生变化,因此在预先设置的可调区间内对初始滤噪强度进行动态调整。例如,若初始滤噪强度为1.8,预先设置的可调区间为1.8~7.0,则后续可以根据第二能量特征参数的变化,以及第二能量特征参数与初始第二能量特征参数的比对结果,在1.8~7.0的范围内调整滤噪强度。其中,可调区间和具体的调节幅度可以根据实验获得或根据理论计算获得。
在一个实施例中,激光测距装置的视场区域包括多个子区域,在调节滤噪强度时,可以分别根据不同子区域对应的第二能量特征参数,确定不同子区域对应的滤噪强度,从而提高滤噪强度的准确性。示例性地,至少两个子区域的 第二能量特征参数与滤噪强度之间的对应关系不同,可以预先分别对不同子区域的第二能量特征参数与滤噪强度之间的对应关系进行标定。在一些实施例中,至少两个子区域也可以应用相同的对应关系。
在一些实施例中,滤噪强度还与深度有关。例如,根据用户的需求,在较近距离处不允许存在噪点,因此滤噪强度较大;相对较远距离处可以存在少量噪点,因此滤噪强度较小。因此,还可以获取融合信号的深度参数,并根据第二能量特征参数和深度参数共同确定滤噪强度。
进一步地,在根据第二能量特征参数和深度参数确定滤噪强度时,首先确定深度参数所对应的深度区间,之后根据深度区间确定第二能量特征参数与滤噪强度的对应关系,并根据该对应关系确定第二能量特征参数对应的滤噪强度。也就是说,在确定第二能量特征参数之后,在不同深度区间内应用不同的对应关系来根据第二能量特征参数得到滤噪强度。
例如,在0.4m以内,第二能量特征参数与滤噪强度适用一种对应关系,在0.4m至2m之间,第二能量特征参数与滤噪强度适用另外一种对应关系。由此,根据相同的第二能量特征参数,不同深度区间内的滤噪强度不同。示例性地,可以分三个或者更多深度区间进行滤噪强度的设置,不同深度区间的边界值可以在出厂前通过老化测试过程监测得到,并写入到固件中。
在一些实施例中,上述深度区间也可以由用户自行设置,使得滤噪策略更能满足用户需求。例如,若用户要求0.5m以内不允许出现较多噪点,因而可以将深度区间的边界值设置为0.5m;具体地,可以提供用户接口,通过用户接口接收调节深度区间的范围的第一用户指令,并根据第一用户指令对深度区间的范围进行调节。
进一步地,还可以通过用户接口接收调节不同深度区间的第二能量特征参数与滤噪强度的对应关系的第二用户指令,并根据第二用户指令对不同深度区间的第二能量特征参数与滤噪强度的对应关系进行调节。例如,对于0.5m以内的深度区间,若用户认为当前的滤噪强度仍然不能满足需求,则可以对滤噪强度的档位进行调节,使得0.5m以内同一第二能量特征参数能够映射到更大的滤噪强度。
之后,在步骤S750,根据第二能量特征参数和滤噪强度确定滤噪范围;并在步骤S760,将第一能量特征参数与滤噪范围进行比对,以识别融合信号 中的噪声信号。示例性地,若第一能量特征参数不高于滤噪范围,则表示目标反射光在融合信号中不占主导,因此将对应的融合信号判定为噪声信号。
示例性地,滤噪范围可以是第二能量特征参数与滤噪强度的乘积,即滤噪强度代表系数;但滤噪范围不限于此,例如,滤噪强度也可以代表指数。当滤噪强度代表指数时,对于融合信号来说,若其第一能量特征参数为单一内部反射光的第二能量特征参数的N倍以上,则可以认为融合信号中的目标反射光占主导,进而将其判定为可正常计算深度的有效信号。若融合信号的第一能量特征参数不高于内部反射光的第二能量特征参数的N倍,则可以认为融合信号中由内部反射光占主导,若根据融合信号计算深度值将产生较大误差,因而此时可以判断融合信号为噪声信号。例如,以A1表示第一能量特征参数,以A2表示第二能量特征参数,以N表示滤噪强度,则滤噪范围可以表示为N·A2;若A1>N·A2,则将对应的融合信号判定为有效信号,若A1≤N·A2,则将对应的融合信号判定为噪声信号。
当然,上述判断过程也可以表示为:若第二能量特征参数与第一能量特征参数的比值不高于所述滤噪强度,则将对应的融合信号判定为噪声信号,即若A1/A2>N,则将对应的融合信号判定为有效信号,若A1/A2≤N,则将对应的融合信号判定为噪声信号。
在一些实施例中,在识别出融合信号中的噪声信号以后,可以滤除噪声信号。之后,可以根据滤除噪声信号后的回光脉冲信号生成点云数据,并向上层运算平台输出点云数据。由此,在底层直接滤除噪声信号,避免了由上层运算平台进行滤噪所造成的消耗运算资源以及存在延时的问题。
在其他实施例中,也可以对噪声信号进行标记,由上层运算平台根据需要决定对噪声信号进行滤除或进行其他分析。具体地,激光测距装置可以根据回光脉冲信号生成点云数据,并对点云数据中对应于噪声信号的点云点添加异常点标记。之后,激光测距装置可以向上层运算平台输出点云数据,根据其中的异常点标记,上层运算平台可以直接辨别其中由噪声信号导致的点云点,并在需要进行滤噪处理时快速去除这部分点云点,而无需增加额外的运算量来对噪点进行识别。
综上,本发明实施例的激光测距方法700以内部反射光的能量特征参数为依据确定滤噪强度,进而根据内部反射光的能量特征参数和滤噪强度确定用于 对融合信号进行滤噪的滤噪范围,从而基于融合信号与内部反射光的能量特征参数之间的相对关系实时地识别出融合信号中的噪声信号,所需的运算量少,处理结果无延时且准确度高,能够显著提升激光测距装置近处测量结果的可靠性。
以上示例性地描述了根据本发明实施例的测距方法。下面重新参照图1描述根据本发明实施例提供的激光测距装置100。根据本发明实施例的激光测距装置100可以用于实现上文中描述的根据本发明实施例的激光测距方法700。为了简洁,下文中仅对激光测距装置100的主要结构和功能进行描述,而省略上文中已经描述的部分具体细节。
如图1所示,激光测距装置100包括发射电路110、接收电路120和运算电路140。其中,发射电路110用于发射激光脉冲信号;接收电路120用于接收回光脉冲信号;运算电路140用于:确定所述回光脉冲信号中的融合信号,所述融合信号为所述激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号;确定所述融合信号的第一能量特征参数;确定所述内部反射光的第二能量特征参数,并根据所述第二能量特征参数确定滤噪强度;根据所述第二能量特征参数和所述滤噪强度确定滤噪范围;将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号是否为噪声信号。进一步地,激光测距装置100还可以包括采样电路130和控制电路150。激光测距装置100的其他具体结构可以参照上文对图1和图2的激光测距装置进行的相关描述。
在一个实施例中,所述将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号中的噪声信号,包括:
若所述第一能量特征参数不高于所述滤噪范围,则判断所述融合信号为噪声信号。
在一个实施例中,所述滤噪范围包括所述第二能量特征参数与所述滤噪强度的乘积。
在一个实施例中,所述确定所述内部反射光的第二能量特征参数,包括:实时测量所述内部反射光的第二能量特征参数;或者,根据第二能量特征参数随运行时间的变化关系确定所述第二能量特征参数。
在一个实施例中,所述根据所述第二能量特征参数确定滤噪强度,包括: 根据所述第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定所述滤噪强度。
在一个实施例中,所述根据所述第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定所述滤噪强度,包括:获取预先标定的初始第二能量特征参数、以及根据所述初始第二能量特征参数确定的初始滤噪强度;将当前的所述第二能量特征参数与所述初始第二能量特征参数进行比对,以得到比对结果;根据所述比对结果,在预先设置的可调区间内对所述初始滤噪强度进行调节,以得到当前的所述滤噪强度。
在一个实施例中,所述第二能量特征参数越大,则所述滤噪强度越高。
在一个实施例中,所述激光测距装置的视场区域包括多个子区域,所述根据所述第二能量特征参数确定滤噪强度,包括:分别根据不同子区域对应的所述第二能量特征参数,确定不同子区域对应的所述滤噪强度。
在一个实施例中,至少两个子区域的所述第二能量特征参数与所述滤噪强度之间的对应关系不同。
在一个实施例中,所述方法还包括:获取所述回光脉冲信号的深度参数;所述根据所述第二能量特征参数确定当前时刻的滤噪强度,包括:根据所述第二能量特征参数和所述深度参数确定所述滤噪强度。
在一个实施例中,所述根据所述第二能量特征参数和所述深度参数确定所述滤噪强度,包括:确定所述深度参数所对应的深度区间;根据所述深度区间确定所述第二能量特征参数与所述滤噪强度的对应关系,并根据所述对应关系确定所述第二能量特征参数对应的滤噪强度。
在一个实施例中,所述激光测距装置还包括用户接口,用于接收调节所述深度区间的范围的第一用户指令;所述运算电路还用于根据所述第一用户指令对所述深度区间的范围进行调节。
在一个实施例中,所述激光测距装置还包括用户接口,用于接收调节不同深度区间的所述第二能量特征参数与所述滤噪强度的对应关系的第二用户指令;所述运算电路还用于根据所述第二用户指令对不同深度区间的所述第二能量特征参数与所述滤噪强度的对应关系进行调节。
在一个实施例中,所述运算电路还用于:根据所述回光脉冲信号生成点云数据;对所述点云数据中对应于所述噪声信号的点云点添加异常点标记;输出 所述点云数据。
在一个实施例中,所述运算电路还用于:滤除所述噪声信号。
在一个实施例中,所述激光测距装置为采用同轴光路的激光测距装置。
本发明实施例的激光测距装置基于融合信号与内部反射光的能量特征参数的相对关系实时地识别出融合信号中的噪声信号,所需的运算量少,处理结果无延时且准确度高,能够显著提升激光测距装置近处测量结果的可靠性。
本发明实施例还提供了一种可移动平台,所述可移动平台包括上述任一激光测距装置以及可移动平台本体,所述激光测距装置搭载在所述可移动平台本体上。在某些实施方式中,可移动平台包括无人飞行器、汽车、遥控车、机器人、相机、云台中的至少一种。当可移动平台为无人飞行器时,可移动平台本体为无人飞行器的机身。当可移动平台为汽车时,可移动平台本体为汽车的车身。该汽车可以是自动驾驶汽车或者半自动驾驶汽车,在此不做限制。当可移动平台为遥控车时,可移动平台本体为遥控车的车身。当可移动平台为机器人时,可移动平台本体为机器人。当可移动平台为相机时,可移动平台本体为相机本身。当可移动平台为云台时,可移动平台本体为云台本体。
由于可移动平台采用了根据本发明实施例的激光测距装置,因而也具备了上文所述的优点。
在上述实施例中,可以全部或部分地通过软件、硬件、固件或者其他任意组合来实现。当使用软件实现时,可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时,全部或部分地产生按照本发明实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中,或者从一个计算机可读存储介质向另一个计算机可读存储介质传输,例如,所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line,DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如,软盘、硬盘、磁带)、光介质(例如数字视频光盘(digital video disc, DVD))、或者半导体介质(例如固态硬盘(solid state disk,SSD))等。
尽管这里已经参考附图描述了示例实施例,应理解上述示例实施例仅仅是示例性的,并且不意图将本发明的范围限制于此。本领域普通技术人员可以在其中进行各种改变和修改,而不偏离本发明的范围和精神。所有这些改变和修改意在被包括在所附权利要求所要求的本发明的范围之内。
本领域普通技术人员可以意识到,结合本文中所公开的实施例描述的各示例的单元及算法步骤,能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行,取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能,但是这种实现不应认为超出本发明的范围。
在本申请所提供的几个实施例中,应该理解到,所揭露的设备和方法,可以通过其它的方式实现。例如,以上所描述的设备实施例仅仅是示意性的,例如,所述单元的划分,仅仅为一种逻辑功能划分,实际实现时可以有另外的划分方式,例如多个单元或组件可以结合或者可以集成到另一个设备,或一些特征可以忽略,或不执行。
在此处所提供的说明书中,说明了大量具体细节。然而,能够理解,本发明的实施例可以在没有这些具体细节的情况下实践。在一些实例中,并未详细示出公知的方法、结构和技术,以便不模糊对本说明书的理解。
类似地,应当理解,为了精简本发明并帮助理解各个发明方面中的一个或多个,在对本发明的示例性实施例的描述中,本发明的各个特征有时被一起分组到单个实施例、图、或者对其的描述中。然而,并不应将该本发明的方法解释成反映如下意图:即所要求保护的本发明要求比在每个权利要求中所明确记载的特征更多的特征。更确切地说,如相应的权利要求书所反映的那样,其发明点在于可以用少于某个公开的单个实施例的所有特征的特征来解决相应的技术问题。因此,遵循具体实施方式的权利要求书由此明确地并入该具体实施方式,其中每个权利要求本身都作为本发明的单独实施例。
本领域的技术人员可以理解,除了特征之间相互排斥之外,可以采用任何组合对本说明书(包括伴随的权利要求、摘要和附图)中公开的所有特征以及如此公开的任何方法或者设备的所有过程或单元进行组合。除非另外明确陈述,本说明书(包括伴随的权利要求、摘要和附图)中公开的每个特征可以由提供 相同、等同或相似目的替代特征来代替。
此外,本领域的技术人员能够理解,尽管在此所述的一些实施例包括其它实施例中所包括的某些特征而不是其它特征,但是不同实施例的特征的组合意味着处于本发明的范围之内并且形成不同的实施例。例如,在权利要求书中,所要求保护的实施例的任意之一都可以以任意的组合方式来使用。
本发明的各个部件实施例可以以硬件实现,或者以在一个或者多个处理器上运行的软件模块实现,或者以它们的组合实现。本领域的技术人员应当理解,可以在实践中使用微处理器或者数字信号处理器(DSP)来实现根据本发明实施例的一些模块的一些或者全部功能。本发明还可以实现为用于执行这里所描述的方法的一部分或者全部的装置程序(例如,计算机程序和计算机程序产品)。这样的实现本发明的程序可以存储在计算机可读介质上,或者可以具有一个或者多个信号的形式。这样的信号可以从因特网网站上下载得到,或者在载体信号上提供,或者以任何其他形式提供。
应该注意的是上述实施例对本发明进行说明而不是对本发明进行限制,并且本领域技术人员在不脱离所附权利要求的范围的情况下可设计出替换实施例。在权利要求中,不应将位于括号之间的任何参考符号构造成对权利要求的限制。本发明可以借助于包括有若干不同元件的硬件以及借助于适当编程的计算机来实现。在列举了若干装置的单元权利要求中,这些装置中的若干个可以是通过同一个硬件项来具体体现。单词第一、第二、以及第三等的使用不表示任何顺序。可将这些单词解释为名称。

Claims (33)

  1. 一种激光测距方法,其特征在于,所述方法包括:
    发射激光脉冲信号,并接收回光脉冲信号;
    确定所述回光脉冲信号中的融合信号,所述融合信号为所述激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号;
    确定所述融合信号的第一能量特征参数;
    确定所述内部反射光的第二能量特征参数,并根据所述第二能量特征参数确定滤噪强度;
    根据所述第二能量特征参数和所述滤噪强度确定滤噪范围;
    将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号是否为噪声信号。
  2. 根据权利要求1所述的激光测距方法,其特征在于,所述将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号中的噪声信号,包括:
    若所述第一能量特征参数不高于所述滤噪范围,则判断所述融合信号为噪声信号。
  3. 根据权利要求2所述的激光测距方法,其特征在于,所述滤噪范围包括所述第二能量特征参数与所述滤噪强度的乘积。
  4. 根据权利要求1所述的激光测距方法,其特征在于,所述确定所述内部反射光的第二能量特征参数,包括:
    实时测量所述内部反射光的第二能量特征参数;
    或者,根据第二能量特征参数随运行时间的变化关系确定所述第二能量特征参数。
  5. 根据权利要求1所述的激光测距方法,其特征在于,所述根据所述第二能量特征参数确定滤噪强度,包括:
    根据所述第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定所述滤噪强度。
  6. 根据权利要求5所述的激光测距方法,其特征在于,所述根据所述第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定所述滤噪强度,包括:
    获取预先标定的初始第二能量特征参数、以及根据所述初始第二能量特征参数确定的初始滤噪强度;
    将当前的所述第二能量特征参数与所述初始第二能量特征参数进行比对,以得到比对结果;
    根据所述比对结果,在预先设置的可调区间内对所述初始滤噪强度进行调节,以得到当前的所述滤噪强度。
  7. 根据权利要求1-6中任一项所述的激光测距方法,其特征在于,所述第二能量特征参数越大,则所述滤噪强度越高。
  8. 根据权利要求1-7中任一项所述的激光测距方法,其特征在于,所述激光测距装置的视场区域包括多个子区域,所述根据所述第二能量特征参数确定滤噪强度,包括:
    分别根据不同子区域对应的所述第二能量特征参数,确定不同子区域对应的所述滤噪强度。
  9. 根据权利要求8所述的激光测距方法,其特征在于,至少两个子区域的所述第二能量特征参数与所述滤噪强度之间的对应关系不同。
  10. 根据权利要求1-9中任一项所述的激光测距方法,其特征在于,所述方法还包括:获取所述融合信号的深度参数;所述根据所述第二能量特征参数确定当前时刻的滤噪强度,包括:
    根据所述第二能量特征参数和所述深度参数确定所述滤噪强度。
  11. 根据权利要求10所述的激光测距方法,其特征在于,所述根据所述第二能量特征参数和所述深度参数确定所述滤噪强度,包括:
    确定所述深度参数所对应的深度区间;
    根据所述深度区间确定所述第二能量特征参数与所述滤噪强度的对应关系,并根据所述对应关系确定所述第二能量特征参数对应的滤噪强度。
  12. 根据权利要求11所述的激光测距方法,其特征在于,还包括:
    通过用户接口接收调节所述深度区间的范围的第一用户指令;
    根据所述第一用户指令对所述深度区间的范围进行调节。
  13. 根据权利要求11所述的激光测距方法,其特征在于,还包括:
    通过用户接口接收调节不同深度区间的所述第二能量特征参数与所述滤噪强度的对应关系的第二用户指令;
    根据所述第二用户指令对不同深度区间的所述第二能量特征参数与所述滤噪强度的对应关系进行调节。
  14. 根据权利要求1所述的激光测距方法,其特征在于,还包括:
    根据所述回光脉冲信号生成点云数据;
    对所述点云数据中对应于所述噪声信号的点云点添加异常点标记;
    输出所述点云数据。
  15. 根据权利要求1所述的激光测距方法,其特征在于,还包括:滤除所述噪声信号。
  16. 根据权利要求1-15中任一项所述的激光测距方法,其特征在于,所述激光测距装置为采用同轴光路的激光测距装置。
  17. 一种激光测距装置,其特征在于,所述激光测距装置包括:
    发射电路,用于发射激光脉冲信号;
    接收电路,用于接收回光脉冲信号;
    运算电路,用于:
    确定所述回光脉冲信号中的融合信号,所述融合信号为所述激光脉冲信号经被测物反射所得到的目标反射光与激光测距装置的内部反射光的融合信号;
    确定所述融合信号的第一能量特征参数;
    确定所述内部反射光的第二能量特征参数,并根据所述第二能量特征参数确定滤噪强度;
    根据所述第二能量特征参数和所述滤噪强度确定滤噪范围;
    将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号中的噪声信号。
  18. 根据权利要求17所述的激光测距装置,其特征在于,所述将所述第一能量特征参数与所述滤噪范围进行比对,以确定所述融合信号中的噪声信号,包括:
    若所述第一能量特征参数不高于所述滤噪范围,则判断所述融合信号为噪声信号。
  19. 根据权利要求18所述的激光测距装置,其特征在于,所述滤噪范围包括所述第二能量特征参数与所述滤噪强度的乘积。
  20. 根据权利要求17所述的激光测距装置,其特征在于,所述确定所述 内部反射光的第二能量特征参数,包括:
    实时测量所述内部反射光的第二能量特征参数;
    或者,根据第二能量特征参数随运行时间的变化关系确定所述第二能量特征参数。
  21. 根据权利要求17所述的激光测距装置,其特征在于,所述根据所述第二能量特征参数确定滤噪强度,包括:
    根据所述第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定所述滤噪强度。
  22. 根据权利要求21所述的激光测距装置,其特征在于,所述根据所述第二能量特征参数、以及预先设置的不同第二能量特征参数与不同滤噪强度之间的对应关系,确定所述滤噪强度,包括:
    获取预先标定的初始第二能量特征参数、以及根据所述初始第二能量特征参数确定的初始滤噪强度;
    将当前的所述第二能量特征参数与所述初始第二能量特征参数进行比对,以得到比对结果;
    根据所述比对结果,在预先设置的可调区间内对所述初始滤噪强度进行调节,以得到当前的所述滤噪强度。
  23. 根据权利要求17-22中任一项所述的激光测距装置,其特征在于,所述第二能量特征参数越大,则所述滤噪强度越高。
  24. 根据权利要求17-23中任一项所述的激光测距装置,其特征在于,所述激光测距装置的视场区域包括多个子区域,所述根据所述第二能量特征参数确定滤噪强度,包括:
    分别根据不同子区域对应的所述第二能量特征参数,确定不同子区域对应的所述滤噪强度。
  25. 根据权利要求24所述的激光测距装置,其特征在于,至少两个子区域的所述第二能量特征参数与所述滤噪强度之间的对应关系不同。
  26. 根据权利要求17-25中任一项所述的激光测距装置,其特征在于,所述方法还包括:获取所述融合信号的深度参数;所述根据所述第二能量特征参数确定当前时刻的滤噪强度,包括:
    根据所述第二能量特征参数和所述深度参数确定所述滤噪强度。
  27. 根据权利要求26所述的激光测距装置,其特征在于,所述根据所述第二能量特征参数和所述深度参数确定所述滤噪强度,包括:
    确定所述深度参数所对应的深度区间;
    根据所述深度区间确定所述第二能量特征参数与所述滤噪强度的对应关系,并根据所述对应关系确定所述第二能量特征参数对应的滤噪强度。
  28. 根据权利要求27所述的激光测距装置,其特征在于,所述激光测距装置还包括用户接口,用于接收调节所述深度区间的范围的第一用户指令;
    所述运算电路还用于根据所述第一用户指令对所述深度区间的范围进行调节。
  29. 根据权利要求28所述的激光测距装置,其特征在于,所述激光测距装置还包括用户接口,用于接收调节不同深度区间的所述第二能量特征参数与所述滤噪强度的对应关系的第二用户指令;
    所述运算电路还用于根据所述第二用户指令对不同深度区间的所述第二能量特征参数与所述滤噪强度的对应关系进行调节。
  30. 根据权利要求29所述的激光测距装置,其特征在于,所述运算电路还用于:
    根据所述回光脉冲信号生成点云数据;
    对所述点云数据中对应于所述噪声信号的点云点添加异常点标记;
    输出所述点云数据。
  31. 根据权利要求30所述的激光测距装置,其特征在于,所述运算电路还用于:滤除所述噪声信号。
  32. 根据权利要求17-31中任一项所述的激光测距装置,其特征在于,所述激光测距装置为采用同轴光路的激光测距装置。
  33. 一种可移动平台,其特征在于,所述可移动平台包括:
    可移动平台本体;
    根据权利要求17-32中任一项所述的激光测距装置,所述激光测距装置搭载于所述可移动平台本体上。
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