WO2020107250A1 - Circuit de réception laser, dispositif de mesure de distance et plateforme mobile - Google Patents

Circuit de réception laser, dispositif de mesure de distance et plateforme mobile Download PDF

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Publication number
WO2020107250A1
WO2020107250A1 PCT/CN2018/117835 CN2018117835W WO2020107250A1 WO 2020107250 A1 WO2020107250 A1 WO 2020107250A1 CN 2018117835 W CN2018117835 W CN 2018117835W WO 2020107250 A1 WO2020107250 A1 WO 2020107250A1
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Prior art keywords
circuit
electrical signal
low
frequency
signal
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PCT/CN2018/117835
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English (en)
Chinese (zh)
Inventor
马亮亮
洪小平
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深圳市大疆创新科技有限公司
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Application filed by 深圳市大疆创新科技有限公司 filed Critical 深圳市大疆创新科技有限公司
Priority to PCT/CN2018/117835 priority Critical patent/WO2020107250A1/fr
Priority to CN201880016698.2A priority patent/CN111492261B/zh
Publication of WO2020107250A1 publication Critical patent/WO2020107250A1/fr

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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

Definitions

  • the invention relates to the technical field of laser radar, in particular to a laser receiving circuit, a distance measuring device and a mobile platform.
  • Lidar is a radar system that emits laser beams to detect the target's position, speed and other characteristic quantities.
  • the light sensor of the lidar can convert the acquired light pulse signal into an electrical signal, and obtain the time information corresponding to the electrical signal based on the comparator, thereby obtaining the distance information between the lidar and the target.
  • the intensity of ambient light will have a significant impact on the performance of the ranging.
  • a large amount of optical noise will be generated under strong background light, and the deterioration of the signal-to-noise ratio will lead to a shorter measurement distance;
  • the measurement distance can be increased by lowering the trigger threshold (in the dark environment, the signal-to-noise ratio is improved). Under this strategy, the measurement of ambient light will be important.
  • a first aspect of the present invention provides a laser receiving circuit, including: a photoelectric conversion circuit and a separation circuit;
  • the photoelectric conversion circuit is used to receive an optical signal and convert the optical signal into an electrical signal, the optical signal includes an optical pulse signal reflected by an object and an ambient light signal;
  • the separation circuit is used to separate the electrical signal into a high-frequency electrical signal and a low-frequency electrical signal, the frequency of the high-frequency electrical signal is at least 10 times higher than the frequency of the low-frequency electrical signal,
  • the ambient light information acquisition circuit is configured to acquire information of the ambient light signal according to the low-frequency electrical signal.
  • the separation circuit includes two branches connected in parallel to each other, one of which is a high-frequency response circuit for responding only to the high-frequency electrical signal to filter out the low-frequency electrical signal;
  • the other branch is a low-frequency response circuit for responding only to the low-frequency electrical signal to filter out the high-frequency electrical signal, thereby separating the high-frequency electrical signal and the low-frequency electrical signal.
  • the high-frequency response circuit includes a high-speed amplifier and an AC coupler connected in series with each other;
  • the AC coupler performs AC coupling with the high-speed amplifier to filter the low-frequency electrical signal, and the high-speed amplifier is used to amplify the high-frequency electrical signal.
  • the AC coupler includes at least one capacitor, and/or the high-speed amplifier includes at least one high-speed transimpedance amplifier.
  • the low-frequency response circuit includes at least one low-speed transimpedance amplifier.
  • the low-frequency response circuit at least includes a current mirror for directly outputting or amplifying the low-frequency electrical signal by multiple times.
  • the low-frequency response circuit further includes a first amplification circuit and/or an electrical signal conversion circuit
  • the first amplifying circuit is used to amplify the electric signal output by the current mirror
  • the electrical signal conversion circuit includes at least one resistor for converting the current signal output by the current mirror into a voltage signal.
  • the current mirror includes at least one of a BJT device, a MOSFET device, and a JFET device.
  • the separation circuit further includes an amplifier connected in series between the photoelectric conversion circuit and the separation circuit to amplify the high-frequency electrical signal and the low-frequency electrical signal.
  • the low-frequency response circuit includes a low-pass filter and a second amplification circuit connected in series to each other;
  • the low-frequency response circuit further includes a two-stage amplifying circuit to further amplify the low-frequency electrical signal responsive to the low-frequency response circuit.
  • the photoelectric conversion circuit includes a photosensitive sensor for receiving the laser pulse signal and converting the laser pulse signal into an electrical signal.
  • the ambient light information acquisition circuit prestores data on the correspondence between the light intensity under different ambient light intensities and the low-frequency electrical signal
  • the ambient light information acquisition circuit determines the light intensity of the ambient light based on the measured value of the low-frequency electrical signal and the corresponding relationship.
  • the light intensity under the different ambient light intensity has a linear relationship with the low-frequency voltage.
  • the frequency of the high-frequency electrical signal is at least 50 times higher than the frequency of the low-frequency electrical signal.
  • the invention also provides a distance measuring device, including:
  • Light emitting circuit used to emit laser pulse signal
  • the laser receiving circuit as described above is used for receiving an optical signal and converting the optical signal into an electrical signal, wherein the optical signal includes an optical pulse signal and an ambient light signal reflected back by an object, and the electrical signal Separating into a high-frequency electrical signal and a low-frequency electrical signal, and acquiring information of the ambient light signal according to the low-frequency electrical signal;
  • a sampling circuit configured to sample the high-frequency electrical signal separated by the laser receiving circuit to obtain a sampling result
  • the arithmetic circuit is used for calculating the distance between the object and the distance measuring device according to the sampling result.
  • the sampling circuit further includes a comparison circuit, configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • a comparison circuit configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • the comparison circuit includes at least one comparator, a first input terminal of the comparator is used to receive the electrical signal input from the laser receiving circuit, and a second input terminal of the comparator is used to receive According to the preset threshold, the output terminal of the comparator is used to output the result of the comparison operation, where the result of the comparison operation includes time information corresponding to the electrical signal.
  • the comparison circuit further includes a time-to-digital converter, and the time-to-digital converter is electrically connected to the output terminal of the comparator, and is used to extract and compare with the result of the comparison operation output by the comparator Time information corresponding to electrical signals.
  • the invention also provides a mobile platform, including:
  • a platform body, the distance measuring device is installed on the platform body.
  • the mobile platform includes at least one of an unmanned aerial vehicle, a car, and a robot.
  • the present invention provides the above-mentioned laser receiving circuit, distance measuring device, and mobile platform.
  • the laser receiving circuit separates the electrical signal into a high-frequency electrical signal and a low-frequency electrical signal through a separation circuit.
  • the frequency of the high-frequency electrical signal is higher than At least 10 times the frequency of the low-frequency electrical signal, and at the same time obtain the information of the ambient light signal according to the low-frequency electrical signal through the ambient light information acquisition circuit, so as to dynamically adjust the trigger threshold for different ambient light, when the light is weak Significantly increase the measurement distance.
  • FIG. 1 is a schematic structural diagram of a laser receiving circuit provided by an embodiment of the present invention.
  • FIG. 2 is a schematic structural diagram of a laser receiving circuit provided by another embodiment of the present invention.
  • FIG. 3 is a schematic structural diagram of a laser receiving circuit according to another embodiment of the present invention.
  • FIG. 4 is a schematic frame diagram of a distance measuring device according to an embodiment of the present invention.
  • FIG. 5 is a schematic diagram of an embodiment of a distance measuring device provided by an embodiment of the present invention using a coaxial optical path.
  • the intensity of ambient light will have a significant impact on the performance of ranging, and the measurement of ambient light is becoming more and more important.
  • TOF mean-of-flight, time-of-flight
  • the signal-to-noise ratio directly affects the range, and an increase in the signal-to-noise ratio will increase the measurement distance.
  • an optical device working outdoors it is susceptible to the influence of external sunlight. Under strong light, the increase of optical noise will significantly reduce the signal-to-noise ratio of the receiving system, resulting in a lower range.
  • the trigger threshold In laser distance measurement, when there is ambient light The intensity of the noise is relatively large, and the trigger threshold is also high, while the signal and noise intensity are relatively small when there is no ambient light, and the trigger threshold is also low.
  • the noise of the analog circuit output will increase significantly in sunlight.
  • the trigger threshold In order to prevent false triggering in sunlight, the trigger threshold needs to be increased. However, increasing the trigger threshold will result in small signals that cannot be triggered in low light, and the effective optical signal will be leaked. In this case, the threshold voltage can be further lowered to increase the measurement distance and improve the weak environment Light time performance.
  • the existing laser ranging receiving circuit is greatly affected by ambient light, and the output noise of the circuit will increase significantly under strong background light.
  • the judgment threshold needs to be set relatively high, which will As a result, the measurement distance becomes shorter in low light.
  • multiple sets of sensors are generally used for environmental measurement.
  • a visual system such as a camera during the day can achieve effective environmental measurement, but the performance of the visual system will seriously deteriorate at night. At this time, it can form an effective complement with the laser ranging system.
  • the preset threshold can be adjusted to increase the range. At this time, the measurement of ambient light will be very important.
  • the present invention provides a laser receiving circuit to realize the measurement of the background light intensity, so that it can adapt to different judgment thresholds under different background light intensity.
  • the laser receiving circuit includes: a photoelectric conversion circuit and a separation Circuit.
  • the photoelectric conversion circuit includes a photosensitive sensor. After receiving the optical pulse signal, the photoelectric conversion circuit converts the optical pulse signal into an electrical pulse signal.
  • the electrical pulse signal includes a voltage pulse signal or a current pulse signal, and is not limited to a certain one.
  • the photoelectric conversion circuit includes an APD (avalanche photodiode) or PIN.
  • the laser receiving circuit further includes a power management circuit for providing a reverse bias voltage to the avalanche photodiode, the avalanche photodiode is used to receive the optical pulse signal, and convert the optical pulse signal into an electrical signal, and The electrical signal is output to the separation circuit.
  • the separation circuit includes two branches connected in parallel with each other, one of which is a high-frequency response circuit,
  • the other branch is a low-frequency response circuit.
  • the frequency of the high-frequency electrical signal is at least 50 times higher than the frequency of the low-frequency electrical signal.
  • the frequency of the high-frequency electrical signal is at least 100 times higher than the frequency of the low-frequency electrical signal.
  • the high-frequency response circuit includes a high-speed amplifier and an AC coupler connected in series with each other; the AC coupler includes, for example, at least one capacitor, or other components that can filter out low-frequency electrical signals and electrical signals, and does not Limited to a certain kind.
  • the high-speed amplifier includes at least one high-speed transimpedance amplifier (TIA).
  • the TIA is used in a detection device that converts a weak optical signal into an electrical signal and amplifies the signal to a certain intensity and low noise in an optical communication system. Its working principle is : When the photosensitive surface of the photoelectric conversion circuit (such as PIN) is irradiated by the detection light, due to the reverse bias of the pn junction, the photo-generated carriers drift under the action of the electric field and generate a photocurrent in the external circuit; the photocurrent passes through the transimpedance amplifier Amplified output realizes the function of converting optical signals into electrical signals and then amplifying the electrical signals.
  • PIN photosensitive surface of the photoelectric conversion circuit
  • the TIA itself does not have the function of filtering high-frequency electrical signals and low-frequency electrical signals.
  • the filtering function is an AC coupler, which has the same amplification function for high-frequency electrical signals and low-frequency electrical signals, but An AC coupler is provided in the high-frequency response circuit. After the TIA and the AC coupler are AC-coupled, only the high-frequency electrical signal is responded to and amplified.
  • the low-frequency response circuit includes at least one low-speed transimpedance amplifier, wherein the low-speed transimpedance amplifier responds only to low-frequency electrical signals, which filters out high-frequency electrical signals to implement high-frequency electrical signals and low-frequency electrical signals Separation, and amplify low-frequency electrical signals.
  • the low-frequency response circuit includes a low-pass filter and a second amplification circuit connected in series to each other, wherein the low-frequency filter is used to respond only to low-frequency electrical signals, which filters out high-frequency electrical Signal, but the low-frequency filter does not have an amplification function, so a second amplifying circuit is further connected after the low-pass filter, where the second amplifying circuit can use a conventional amplifier, because the low-frequency filter has been set, so only need It suffices to have an amplification function, and the choice is expanded.
  • a low-speed transimpedance amplifier can be provided after the low-frequency filter to achieve the amplification function.
  • the low-frequency response circuit includes a current mirror for directly outputting or amplifying the low-frequency electrical signal by several times.
  • the high-frequency response circuit has one embodiment, that is, it includes a high-speed amplifier and an AC coupler connected in series with each other, and the low-frequency response circuit has three embodiments, namely a low-speed transimpedance amplifier, a current mirror, and a low-frequency Pass filter and second amplifier circuit.
  • the laser receiving circuit of the present invention includes any combination of a high-frequency response circuit and three low-frequency response circuits. The following three specific embodiments of the laser receiving circuit can be obtained. Give a detailed explanation.
  • the high-frequency response circuit includes a high-speed transimpedance amplifier (TIA) and a capacitor C1.
  • the avalanche photodiode is connected to the input terminal of the high-frequency response circuit.
  • the power management circuit is used to provide an inversion for the avalanche photodiode. To bias.
  • the first input terminal of the high-speed transimpedance amplifier (TIA) is electrically connected to one end of the capacitor C1, the other end of the capacitor is electrically connected to the avalanche photodiode, and the second input end of the high-speed transimpedance amplifier (TIA) is
  • the reference circuit is electrically connected to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal can be electrically connected to the sampling circuit.
  • the high-speed transimpedance amplifier (TIA) and the capacitor C1 are coupled to achieve the response of the high-frequency electrical signal while filtering out the low-frequency electrical signal.
  • the low-frequency response circuit is a low-frequency amplification circuit, wherein the low-frequency response circuit includes a low-pass filter and a second amplification circuit connected in series with each other, wherein the low-frequency filter is used to respond only to low-frequency electrical signals, which Filter out high-frequency electrical signals, but the low-frequency filter does not have an amplification function, so a second amplifier circuit is further connected after the low-pass filter, where the second amplifier circuit can use a conventional amplifier, because low-frequency filtering has been set Therefore, it only needs to have an amplifying function, and there is a choice to expand.
  • the shown photosensitive device PIN or APD is connected to the high-frequency response circuit and the low-frequency response circuit of the subsequent stage (where the low-frequency response circuit is connected to the ambient light information acquisition circuit) and outputs HS_TIA_out and DC_out signals.
  • the ambient light Due to the difference in bandwidth between the optical signal and the ambient light, the ambient light appears as a low-frequency DC signal.
  • the low-frequency response circuit separates the ambient light through a low-pass filter. After amplification, the intensity of the ambient light can be reversed by measuring the low-frequency voltage signal. weak.
  • the avalanche photodiode is connected to the input terminal of the high-frequency response circuit, and the power management circuit is used to give the avalanche photodiode Provide reverse bias.
  • TIA high-speed transimpedance amplifier
  • the high-speed transimpedance amplifier (TIA) and the capacitor C1 are AC coupled, high-frequency received optical signals can be coupled into the high-speed transimpedance amplifier TIA through the capacitor C1, and the ambient light signal is filtered.
  • a high-speed transimpedance amplifier (TIA) circuit converts the current into a voltage, and the conversion gain of the TIA is Rf. In order to measure the narrow pulses emitted by the laser, the bandwidth of the TIA circuit is very high.
  • the first input terminal of the high-speed transimpedance amplifier (TIA) is electrically connected to one end of the capacitor C1, the other end of the capacitor is electrically connected to the avalanche photodiode, and the second input end of the high-speed transimpedance amplifier (TIA) is
  • the reference circuit is electrically connected to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal can be electrically connected to the sampling circuit.
  • a low-frequency response circuit is used to select a current mirror.
  • the current mirror is composed of Rin, T1 and T2, which provides DC bias for the APD.
  • the low-frequency received optical signal can enter the low-speed transimpedance amplifier TIA, and the high-frequency optical signal is filtered.
  • the low-frequency response circuit further includes a first amplifying circuit for further amplifying the signal output by the current mirror.
  • the current mirror shown can mirror the low-frequency electrical signal (ambient light signal) onto the first amplifying circuit, through the first amplifying circuit The signal output by the current mirror is further amplified.
  • the current mirror itself can amplify the electrical signal, the current mirror can output the same signal as the ambient light current, and can be amplified after a certain multiple of output, so the current mirror itself can also be set as an element with an amplification function .
  • the low-frequency response circuit selects a current mirror
  • the low-frequency response circuit further includes an electric signal conversion circuit for converting the current signal output by the current mirror into a voltage signal.
  • the electrical signal conversion circuit includes at least one resistor R1. As shown in FIG. 2, the mirror current output by the current mirror generates a voltage drop on R1, and measuring the voltage drop on R1 can inversely obtain the intensity of the background light.
  • FIG. 2 shows a current mirror designed with a BJT bipolar junction transistor (Bipolar Junction Transistor—BJT) device.
  • BJT Bipolar Junction Transistor
  • MOSFET Metal Organic semiconductor field effect transistor
  • JFET Junction Field -Effect Transistor
  • the APD shown in FIG. 2 is a positive high-voltage power supply, and in fact, a negative high-voltage power supply method can also be used, and the direction of the current mirror also needs to be reversed.
  • the high-frequency response circuit includes a high-speed transimpedance amplifier (TIA) and a capacitor C1.
  • the avalanche photodiode is connected to the input terminal of the high-frequency response circuit.
  • the power management circuit is used to provide avalanche photodiode. Provide reverse bias.
  • the high-speed transimpedance amplifier (TIA) and the capacitor C1 are AC coupled, high-frequency received optical signals can be coupled into the high-speed transimpedance amplifier TIA through the capacitor C1, and the ambient light signal is filtered.
  • a high-speed transimpedance amplifier (TIA) circuit converts the current into a voltage, and the conversion gain of the TIA is Rf. In order to measure the narrow pulses emitted by the laser, the bandwidth of the TIA circuit is very high.
  • the first input terminal of the high-speed transimpedance amplifier (TIA) is electrically connected to one end of the capacitor C1, the other end of the capacitor is electrically connected to the avalanche photodiode, and the second input end of the high-speed transimpedance amplifier (TIA) is
  • the reference circuit is electrically connected to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal can be electrically connected to the sampling circuit.
  • a low-frequency response circuit using one channel selects a low-speed transimpedance amplifier to respond to low-frequency electrical signals.
  • the low-speed transimpedance amplifier itself has the function of filtering high-frequency electrical signals, and only responds to low-frequency electrical signals.
  • the first input terminal of the low-speed transimpedance amplifier (TIA) is electrically connected to the avalanche photodiode
  • the second input terminal of the low-speed transimpedance amplifier (TIA) is electrically connected to the reference circuit, and is used for the high-speed transimpedance amplifier ( TIA) provides a reference voltage
  • the output of the low-speed transimpedance amplifier (TIA) can be electrically connected to the ambient light information acquisition circuit.
  • the separation circuit further includes an amplifier connected in series between the photoelectric conversion circuit and the separation circuit to amplify the high-frequency electrical signal and the low-frequency electrical signal.
  • the amplifier circuit uses a high-speed transimpedance amplifier (TIA), the first input terminal of the high-speed transimpedance amplifier is electrically connected to the avalanche photodiode, and the second high-speed transimpedance amplifier (TIA)
  • the input terminal is electrically connected to a reference circuit, and is used to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal is electrically connected to a high-frequency response circuit and a low-frequency response circuit, respectively.
  • TOF ranging needs to read the current signal output by the photosensitive device, convert the current into a voltage through a high-speed transimpedance amplifier (TIA) circuit, and the conversion gain of the TIA is Rf.
  • TIA transimpedance amplifier
  • the bandwidth of the TIA circuit is very high. At this time, it has the same conversion capability for the received optical signal and the ambient optical signal.
  • the low-frequency response circuit further includes a two-stage amplification circuit to perform secondary amplification on the low-frequency electrical signal that the low-frequency response circuit responds to.
  • the ambient light information acquisition circuit prestores data of the correspondence between the light intensity under different ambient light intensities and the low-frequency electrical signal; the ambient light information acquisition circuit is based on the measured low-frequency electrical signal The value and the correspondence determine the light intensity of the ambient light.
  • the output photocurrent is proportional to the input light intensity
  • the conversion of the photocurrent by the laser receiving circuit is also proportional to the input light intensity.
  • k can be obtained by calculation, as long as the photoelectric conversion multiple of the photosensor and the magnification of the circuit are known, the light intensity can be obtained.
  • the voltage signal can be calibrated to the ambient light intensity through calibration. For example, before the machine leaves the factory, the laser receiving circuit is irradiated with ambient light of known light intensity.
  • the circuit will output a voltage, and the output voltage is linear with the input light intensity. Therefore, it is possible to measure the voltage of multiple different ambient lights, calculate the linear factor and record it in the machine. When used, multiply the measured voltage by the linear factor to infer the intensity of the ambient light. The measurement of the ambient light is realized through the above method, and then the preset threshold is adjusted when the ambient light is weak.
  • an embodiment of the present invention further provides a distance measuring device, including a light emitting circuit for emitting a laser pulse signal; the above-mentioned laser receiving circuit for receiving an optical signal and converting the optical signal Converted into an electrical signal, wherein the optical signal includes an optical pulse signal and an ambient light signal reflected back from the object, and the electrical signal is separated into a high-frequency electrical signal and a low-frequency electrical signal, and obtained according to the low-frequency electrical signal Information of the ambient light signal; a sampling circuit for sampling the high-frequency electrical signal separated by the laser receiving circuit to obtain a sampling result; an operation circuit for calculating the object and The distance between the distance measuring devices.
  • a distance measuring device including a light emitting circuit for emitting a laser pulse signal; the above-mentioned laser receiving circuit for receiving an optical signal and converting the optical signal Converted into an electrical signal, wherein the optical signal includes an optical pulse signal and an ambient light signal reflected back from the object, and the electrical signal is separated into a high-frequency electrical signal and a low-
  • the number of the light emitting devices is at least 2.
  • the sampling circuit further includes a comparison circuit, configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • a comparison circuit configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • the comparison circuit includes at least one comparator, a first input terminal of the comparator is used to receive the electrical signal input from the laser receiving circuit, and a second input terminal of the comparator is used to receive According to the preset threshold, the output terminal of the comparator is used to output the result of the comparison operation, where the result of the comparison operation includes time information corresponding to the electrical signal.
  • the comparison circuit further includes a time-to-digital converter (Time-to-Digital Converter, TDC).
  • TDC Time-to-Digital Converter
  • the time-to-digital converter is electrically connected to the output terminal of the comparator, and is used to extract and compare with the result of the comparison operation output by the comparator. Time information corresponding to electrical signals.
  • the preset threshold can be adjusted according to the intensity of the measured ambient light, so that when the ambient light is weak, a normal optical signal can trigger the preset threshold, thereby increasing the measurement distance.
  • the preset threshold can be adjusted in the following ways:
  • the first implementation of adjusting the preset threshold adjusts the voltage of the comparison circuit to adjust the preset threshold of the comparison circuit.
  • the distance measuring device includes a digital-to-analog converter.
  • the digital-to-analog converter can be connected to the input terminal of the comparison circuit, and the preset threshold of the comparison circuit can be adjusted by controlling the output voltage of the digital-to-analog converter.
  • the second implementation of adjusting the preset threshold may be: the distance measuring device may further include a comparison threshold adjustment circuit.
  • the comparison threshold adjustment circuit includes multiple resistors, and one end of the multiple resistors is connected to the comparator At the input end, multiple voltage signals are input to the other end of the multiple resistors to provide a preset threshold value to the input end of the comparator through the multiple resistors.
  • the second input to the comparison circuit is adjusted. The preset threshold at the input.
  • an embodiment of the present invention further provides a mobile platform, the mobile platform includes any of the foregoing distance measuring devices and a platform body, and the distance measuring device is installed on the platform body. Further, the mobile platform includes at least one of a manned aircraft, an unmanned aerial vehicle, a car, a robot, and a remote control car.
  • the light emitting devices provided by the various embodiments of the present invention may be applied to a distance measuring device, and the distance measuring device may be an electronic device such as a laser radar or a laser distance measuring device.
  • the distance measuring device is used to sense external environment information, for example, distance information, azimuth information, reflection intensity information, speed information, etc. of the environmental target.
  • the distance measuring device can detect the distance between the detecting object and the distance measuring device by measuring the time of light propagation between the distance measuring device and the detection object, that is, Time-of-Flight (TOF).
  • TOF Time-of-Flight
  • the distance measuring device may also detect the distance between the detected object and the distance measuring device through other techniques, such as a distance measuring method based on phase shift measurement, or a distance measuring method based on frequency shift measurement. There are no restrictions.
  • the distance measuring device 100 may include a transmitting circuit 110, a receiving circuit 120, a sampling circuit 130, and an arithmetic circuit 140.
  • the transmission circuit 110 may transmit a sequence of light pulses (for example, a sequence of laser pulses).
  • the receiving circuit 120 can receive the optical pulse sequence reflected by the detected object, and photoelectrically convert 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 the 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 apparatus 100 may further include a control circuit 150, which may control other circuits, for example, may control the working time of each circuit and/or set parameters for each circuit.
  • a control circuit 150 may control other circuits, for example, may control the working time of each circuit and/or set parameters for each circuit.
  • the distance measuring device shown in FIG. 4 includes a transmitting circuit, a receiving circuit, a sampling circuit, and an arithmetic circuit
  • the embodiments of the present application are not limited thereto, and the transmitting circuit, the receiving circuit, the sampling circuit, and the arithmetic
  • the number of any of the circuits may be at least two.
  • the distance measuring apparatus 100 may further include a scanning module 160 for changing the propagation direction of the laser pulse sequence emitted by the transmitting circuit.
  • the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, and the arithmetic circuit 140, or the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, the arithmetic circuit 140, and the control circuit 150 may be referred to as measurement
  • the distance measuring module 150 may be independent of other modules, for example, the scanning module 160.
  • a coaxial optical path may be used in the distance measuring device, that is, the light beam emitted by the distance measuring device and the reflected light beam share at least part of the optical path in the distance measuring device.
  • 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. 5 shows a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.
  • the distance measuring device 200 includes a distance measuring module 201.
  • the distance measuring 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) Optical path changing element 206.
  • the ranging module 210 is used to emit a light beam, and receive back light, and convert the back light into an electrical signal.
  • the transmitter 203 may be used to transmit a light pulse sequence.
  • 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 exit optical path of the emitter, and is used to collimate the light beam emitted from the emitter 203, and collimate the light beam emitted from the emitter 203 into parallel light to the scanning module.
  • the collimating element is also used to converge at least a part of the return light reflected by the detection object.
  • the collimating element 204 may be a collimating lens or other element capable of collimating the light beam.
  • the optical path changing element 206 is used to combine the transmitting optical path and the receiving optical path in the distance measuring device before the collimating element 104, 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 transmitter 103 and the detector 105 may respectively use respective collimating elements, and the optical path changing element 206 is disposed on the optical path behind the collimating element.
  • the light path changing element can use a small-area mirror to convert The transmitting optical path and the receiving optical path are combined.
  • the light path changing element may also use a reflector with a through hole, where 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 blocking of the return light by the support of the small mirror in the case of using the small mirror.
  • the optical path changing element is offset from the optical axis of the collimating element 204. In some other implementations, the optical path changing element may also be located on the optical axis of the collimating element 204.
  • the distance measuring device 200 further includes a scanning module 202.
  • the scanning module 202 is placed on the exit optical path of the distance measuring module 201, and the scanning module 102 is used to change the transmission direction of the collimated light beam 219 emitted through 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 converged on the detector 105 via the collimating element 104.
  • the scanning module 202 may include at least one optical element for changing the propagation path of the light beam, wherein the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. the light beam.
  • the scanning module 202 includes a lens, a mirror, a prism, a galvanometer, a grating, a liquid crystal, an optical phased array (Optical Phased Array), or any combination of the above optical elements.
  • at least part of the optical element is moving, for example, the at least part of the optical element is driven to move by a driving module, and the moving optical element can reflect, refract, or diffract the light beam to different directions at different times.
  • multiple optical elements of the scanning module 202 may rotate or vibrate about a common axis 209, and each rotating or vibrating optical element is used to continuously change the direction of propagation of the incident beam.
  • the multiple optical elements of the scanning module 202 may rotate at different rotation speeds, or vibrate at different speeds.
  • at least part of the optical elements of the scanning module 202 can rotate at substantially the same rotational speed.
  • the multiple optical elements of the scanning module may also rotate around different axes.
  • the multiple 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 is not limited herein.
  • the scanning module 202 includes a first optical element 214 and a driver 216 connected to the first optical element 214.
  • the driver 216 is used to drive the first optical element 214 to rotate about a rotation axis 209 to change the first optical element 214 The direction of the collimated light beam 219.
  • the first optical element 214 projects the collimated light beam 219 to different directions.
  • the angle between the direction of the collimated light beam 219 changed by the first optical element and the rotation axis 109 changes as the first optical element 214 rotates.
  • the first optical element 214 includes a pair of opposed non-parallel surfaces through which the collimated light beam 219 passes.
  • the first optical element 214 includes a prism whose thickness varies along at least one radial direction.
  • the first optical element 114 includes a wedge-angle prism that aligns the straight beam 119 for refraction.
  • the scanning module 202 further includes a second optical element 215 that rotates about a rotation axis 209.
  • 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 115 is connected to another driver 217, and the driver 117 drives the second optical element 215 to rotate.
  • the first optical element 214 and the second optical element 215 may be driven by the same or different drivers, so that the first optical element 214 and the second optical element 215 have different rotation speeds and/or rotations, thereby projecting the collimated light beam 219 to the outside 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 rotation speeds of the first optical element 214 and the second optical element 215 can 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 115 includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the second optical element 115 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the second optical element 115 includes a wedge angle prism.
  • the scanning module 102 further includes a third optical element (not shown) and a driver for driving the third optical element to move.
  • the third optical element includes a pair of opposed non-parallel surfaces through which the light beam passes.
  • the third optical element includes a prism whose thickness varies along at least one radial direction.
  • the third optical element includes a wedge angle prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or turns.
  • each optical element in the scanning module 202 can project light into different directions, such as directions 211 and 213, so as to scan the space around the distance measuring device 200.
  • the detector 205 is placed on the same side of the collimating element 204 as the emitter 203.
  • the detector 205 is used to convert at least part of the returned light passing through the collimating element 204 into an electrical signal.
  • each optical element is coated with an antireflection coating.
  • the thickness of the AR coating is equal to or close to the wavelength of the light beam emitted by the emitter 103, which can increase the intensity of the transmitted light beam.
  • a filter layer is coated on the surface of an element on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path to transmit at least the wavelength band of the beam emitted by the transmitter, Reflect other bands to reduce the noise caused by ambient light to the receiver.
  • the transmitter 203 may include a laser diode through which laser pulses in the order of nanoseconds are emitted.
  • the laser pulse receiving time may be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse. In this way, the distance measuring device 200 can calculate the TOF using the pulse reception time information and the pulse emission time information, thereby determining the distance between the detection object 201 and the distance measuring device 200.
  • the distance and orientation detected by the distance measuring 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 mobile platform, and the distance measuring device can be installed on the platform body of the mobile platform.
  • a mobile platform with a distance-measuring device can measure the external environment, for example, measuring the distance between the mobile platform and obstacles for obstacle avoidance and other purposes, and performing two-dimensional or three-dimensional mapping of the external environment.
  • the mobile platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera.
  • the platform body When the distance measuring device is applied to an unmanned aerial vehicle, the platform body is the fuselage of the unmanned aerial vehicle.
  • the platform body When the distance measuring device is applied to an automobile, the platform body is the body of the automobile.
  • the car may be a self-driving car or a semi-automatic car, and no restriction is made here.
  • the platform body When the distance measuring device is applied to a remote control car, the platform body is the body of the remote control car.
  • the platform body When the distance measuring device is applied to a robot, the platform body is a robot.
  • the platform body When the distance measuring device is applied to a camera, the platform body is the camera itself.
  • the present invention provides a laser emission solution that meets human eye safety regulations by providing the above-mentioned light emitting device, ranging device, and mobile platform.
  • the circuit in the above device can ensure that the laser radiation value does not exceed the safety Standard value, so as to ensure the safety of the laser device.

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

Abstract

L'invention concerne un circuit de réception laser, un dispositif de mesure de distance (100) et une plateforme mobile. Le circuit de réception laser comprend un circuit de conversion photoélectrique et un circuit de séparation, le circuit de conversion photoélectrique étant utilisé pour recevoir un signal lumineux et convertir le signal lumineux en un signal électrique, et le signal lumineux comprenant un signal d'impulsion de lumière et un signal de lumière ambiante réfléchi par un objet ; le circuit de séparation est conçu pour séparer le signal électrique en un signal électrique haute fréquence et un signal électrique basse fréquence, la fréquence du signal électrique haute fréquence étant au moins 10 fois supérieure à celle du signal électrique basse fréquence ; un circuit d'acquisition d'informations de lumière ambiante est utilisé pour acquérir les informations du signal de lumière ambiante en fonction du signal électrique basse fréquence. Le circuit de réception laser, le dispositif de mesure de distance (100) et la plateforme mobile peuvent acquérir les informations du signal de lumière ambiante, ce qui permet d'obtenir un seuil de déclenchement lors du réglage dynamique de différentes lumières ambiantes, et d'augmenter significativement une distance de mesure lorsque la lumière est sombre.
PCT/CN2018/117835 2018-11-28 2018-11-28 Circuit de réception laser, dispositif de mesure de distance et plateforme mobile WO2020107250A1 (fr)

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PCT/CN2018/117835 WO2020107250A1 (fr) 2018-11-28 2018-11-28 Circuit de réception laser, dispositif de mesure de distance et plateforme mobile
CN201880016698.2A CN111492261B (zh) 2018-11-28 2018-11-28 一种激光接收电路及测距装置、移动平台

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CN114157356A (zh) * 2021-11-30 2022-03-08 京东方科技集团股份有限公司 感光电路、感光基板及感光装置

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