Laser radar and method and system for measuring target reflectivity thereof

Abstract

Embodiments of this specification provide a laser radar (LIDAR) and a method and system for measuring target reflectivity. The LIDAR includes a detector. The method comprises: obtaining at least one echo pulse signal and an echo energy signal output by the detector after receiving an echo of a probe beam reflected by at least one target; the echo energy signal is adapted to represent all echo energies received by the detector within a detection window; and determining, based on the at least one echo pulse signal, the proportion of the energy of the echo reflected by the at least one target in the echo energy signal to obtain the reflectivity of the at least one target. The above scheme enables reflectivity measurement of multiple echo targets within a ranging range.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of laser radar reflectivity measurement, and in particular to a laser radar and a method and system for measuring target reflectivity thereof. Background Art

[0002] LiDAR is currently widely used in intelligent driving, such as autonomous driving, and in robotics. Its operating principle is to transmit a detection beam, receive the echo reflected by the target through a detector, and obtain target detection information by measuring the time difference between the detection beam and the echo signal.

[0003] When LiDAR is used in intelligent driving, it's prone to encountering multiple-echo scenarios. To ensure driving safety, when measuring target reflectivity in intelligent driving applications, it's important to obtain reflectivity information not only for targets within the range, but also for targets at long distances. Furthermore, it's necessary to obtain reflectivity information for multiple targets in multiple-echo scenarios, enabling target identification based on reflectivity information. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides a laser radar and a method and system for measuring target reflectivity thereof, which can realize reflectivity measurement of multi-echo targets within the ranging range.

[0005] First, an embodiment of the present invention provides a method for measuring target reflectivity using a laser radar, wherein the laser radar includes a detector, and the method includes:

[0006] Respectively acquiring at least one echo pulse signal and an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target; the echo energy signal is suitable for representing all echo energies received by the detector within a detection window;

[0007] The proportion of the energy of the echo reflected by the at least one target in the echo energy signal is determined according to the at least one echo pulse signal to obtain the reflectivity of the at least one target.

[0008] Optionally, determining, based on the at least one echo pulse signal, a proportion of energy of the at least one target reflected echo in the echo energy signal to obtain the reflectivity of the at least one target includes:

[0009] respectively collecting signal features corresponding to the at least one echo pulse signal and the echo energy signal to obtain corresponding pulse signal features and energy signal features;

[0010] determining, according to the pulse signal characteristics, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo;

[0011] When it is determined that the echo received by the detector is a single target reflection echo, determining the reflectivity of the single target according to the energy signal characteristics;

[0012] When it is determined that the echo received by the detector is a multi-target reflected echo, the reflectivity of each target is obtained according to the proportion of the energy of the reflected echo of each target in the echo energy signal.

[0013] Optionally, determining, according to the pulse signal characteristics, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo includes:

[0014] determining the number of pulse groups in the at least one echo pulse signal that conform to the encoding of the transmitted pulse group;

[0015] According to the number of the pulse groups, it is determined whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

[0016] Optionally, before determining, according to the number of the pulse groups, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo, the method further includes:

[0017] An echo pulse whose amplitude exceeds a preset amplitude threshold value is selected from the at least one echo pulse signal.

[0018] Optionally, when it is determined that the echo received by the detector is a multi-target reflected echo, obtaining the reflectivity of each target according to the proportion of the energy of the reflected echo of each target in the echo energy signal includes:

[0019] Acquire the echo signal characteristics of the reflected echo corresponding to each target and their sum according to the pulse signal characteristics;

[0020] The proportion of the echo signal characteristics of each target in the total is used as the proportion of the energy of the echo reflected by each target in the echo energy signal.

[0021] Optionally, the echo signal characteristics of the reflected echo signals corresponding to the respective targets include at least one of the following:

[0022] Pulse peak value, pulse leading edge slope, pulse trailing edge slope, pulse threshold pulse width, and pulse coverage area.

[0023] Optionally, acquiring an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target includes:

[0024] Acquire an ambient light energy signal output by the detector when receiving ambient light;

[0025] The difference between the energy signal received by the detector in the detection window and the ambient light energy signal is used as the echo energy signal.

[0026] Optionally, the echo energy signal is determined according to the integration of the amplitude of the echo electrical signal over time.

[0027] Optionally, the echo electrical signal is at least one of photocurrent, photovoltage, and number of detected photons.

[0028] An embodiment of the present invention further provides a measuring device for measuring target reflectivity using a laser radar, wherein the laser radar includes a detector, and the measuring device includes:

[0029] a first signal acquisition unit, adapted to acquire at least one echo pulse signal output by the detector after receiving an echo of the detection beam reflected by at least one target;

[0030] a second signal acquisition unit, adapted to acquire an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target; the echo energy signal is adapted to represent all echo energies received by the detector within a detection window;

[0031] The processing unit is adapted to determine the proportion of the energy of the echo reflected by the at least one target in the echo energy signal according to the at least one echo pulse signal, and obtain the reflectivity of the at least one target.

[0032] An embodiment of the present invention further provides a laser radar, including:

[0033] a detector adapted to receive and, in response to an echo of the detection light reflected by at least one target, output at least one echo pulse signal and an echo energy signal; the echo energy signal being adapted to represent all echo energies received by the detector within a detection window;

[0034] The processor is coupled to the detector and is adapted to determine the proportion of the energy of the echo reflected by the at least one target in the echo energy signal according to the at least one echo pulse signal, so as to obtain the reflectivity of the at least one target.

[0035] Optionally, the laser radar further includes:

[0036] a first signal collector, adapted to collect a signal feature corresponding to the at least one echo pulse signal to obtain a corresponding pulse signal feature;

[0037] a second signal collector, adapted to collect signal characteristics corresponding to the echo energy signal to obtain corresponding energy signal characteristics;

[0038] The processor is suitable for determining whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo based on the pulse signal characteristics. When it is determined that the echo received by the detector is a single-target reflection echo, the reflectivity of the single target is determined according to the energy signal characteristics; when it is determined that the echo received by the detector is a multi-target reflection echo, the reflectivity of each target is obtained respectively according to the proportion of the energy of each target reflection echo in the echo energy signal.

[0039] Optionally, the processor is adapted to determine the number of pulse groups in the at least one echo pulse signal that conform to the coding of the transmitted pulse group; and determine, based on the number of pulse groups, whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

[0040] Optionally, the processor is adapted to select an echo pulse whose amplitude exceeds a preset amplitude threshold in the at least one echo pulse signal before determining, based on the number of the pulse groups, whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

[0041] Optionally, the processor is suitable for obtaining the echo signal characteristics of the reflected echo corresponding to each target and their sum according to the pulse signal characteristics when determining that the received echo type is a multi-target reflected echo, and taking the proportion of the echo signal characteristics of each target in the total as the proportion of the energy of the reflected echo of each target in the echo energy signal.

[0042] Optionally, the first signal collector includes at least one of the following:

[0043] a first analog-to-digital converter, adapted to sample the at least one echo pulse signal to obtain the pulse signal characteristics;

[0044] a time-to-digital converter, adapted to sample the echo pulse signal to obtain the pulse signal characteristics;

[0045] The second signal collector includes:

[0046] The second analog-to-digital converter is adapted to sample the echo energy signal to obtain the energy signal characteristics.

[0047] Optionally, the detector includes a plurality of single-photon avalanche diodes connected in parallel, and the second analog-to-digital converter is suitable for determining the echo energy signal based on the integral of the amplitude of the echo electrical signal output by the detector over time, and the amplitude of the echo electrical signal is positively correlated with the number of single-photon avalanche diodes triggered in the detector.

[0048] Optionally, the detector includes a silicon photomultiplier tube, and the silicon photomultiplier tube includes two output ports, wherein:

[0049] a first output port, outputting the at least one echo pulse signal;

[0050] The second output port outputs the echo energy signal through a branch circuit.

[0051] Optionally, the first output port includes: a coupling capacitor; the second output port includes: an integration circuit.

[0052] The detector of the laser radar can receive the echo signal of the detection beam reflected by the target, and the laser radar scheme for measuring the target reflectivity in the embodiment of the present invention is adopted to respectively obtain at least one echo pulse signal and echo energy signal output by the detector after receiving the echo of the detection beam reflected by at least one target, and then determine the proportion of the energy of the echo reflected by the at least one target in the echo energy signal based on the at least one echo pulse signal, so as to obtain the reflectivity of at least one target. On the one hand, since the echo energy signal is suitable for representing all echo energies received by the detector within the detection window, on the other hand, the proportion of the energy of the echo reflected by the at least one target in the echo energy signal can be determined based on the at least one echo pulse signal, so that the reflectivity of all targets in the detection window can be obtained, thereby realizing the reflectivity measurement of multiple echo targets within the ranging range, and improving the accuracy and completeness of the target reflectivity measurement.

[0053] Furthermore, during the entire measurement and calculation process, on the one hand, since the pulse signal characteristics obtained based on the echo pulse signal output after the detector receives the target reflection can reflect the echo light intensity, and since the echo pulse signal has the characteristic of narrow pulse width, it is easy to distinguish echoes from different targets based on the pulse signal characteristics. Therefore, first, it is possible to determine whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo based on the pulse signal characteristics. Then, when it is determined that the echo received by the detector is a single-target reflection echo, the reflectivity of the single target can be determined based on the energy signal characteristics; when it is determined that the echo received by the detector is a multi-target reflection echo, the reflectivity of each target is obtained respectively according to the proportion of the energy of each target reflection echo in the echo energy signal, so that the true reflectivity of different targets within the entire ranging range can be accurately measured. Among them, since the dynamic range of the echo pulse signal is very narrow, if only the echo pulse signal characteristics are used, the target reflectivity cannot be accurately measured. However, the use of the echo energy signal characteristics can achieve reflectivity measurement with a high dynamic range. In addition, the echo signal is distinguished and the energy is distributed based on the pulse signal characteristics, so that the reflectivity of different targets within the entire ranging range can be accurately measured, which can improve the dynamic range and measurement accuracy.

[0054] Furthermore, by determining the number of pulse groups in the at least one echo pulse signal that match the coding of the transmitted pulse group, and then determining based on the number of pulse groups whether the type of echo received by the detector is a single-target echo or a multi-target reflection echo, that is, only when the coding of the pulse group matches the coding of the transmitted pulse group, the target corresponding to the pulse group is identified as a real target. Therefore, based on the number of pulse groups that match the coding of the transmitted pulse group, the number of real targets can be determined, thereby further improving the accuracy of multi-target detection of the lidar.

[0055] Furthermore, by selecting the echo pulses whose amplitude exceeds the preset amplitude threshold contained in the at least one echo pulse signal, the interference of noise pulses caused by various optical noises and electrical noises can be filtered out, and the echo pulses of the real target can be extracted, thereby further improving the measurement accuracy.

[0056] Furthermore, based on the pulse signal characteristics, the echo signal characteristics of the reflected echo corresponding to each target and their sum are obtained, and then the proportion of the echo signal characteristics of each target in the total is used as the proportion of the energy of the reflected echo of each target in the echo energy signal. The above method can truly reflect the true reflectivity information of each target in the detection window, thereby improving the accuracy of multi-target detection.

[0057] Furthermore, by obtaining the ambient light energy signal output by the detector when receiving ambient light, and using the difference between the energy signal received by the detector in the detection window and the ambient light energy signal as the echo energy signal, the influence of ambient light on the detection results can be avoided, and the accuracy of the lidar detection results can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0059] Figure 1A A schematic diagram of a circuit structure of a SiPM is shown;

[0060] Figure 1B shows a schematic diagram of the circuit structure of another SiPM;

[0061] Figures 2A to 2C Shows several typical multi-echo scenarios in lidar detection;

[0062] Figure 3 A flow chart of a method for measuring target reflectivity using a laser radar according to an embodiment of the present invention is shown;

[0063] Figure 4A and Figure 4B Schematic diagrams of the waveforms of the echo pulse signal and the echo energy signal are shown respectively;

[0064] Figure 5 A schematic diagram showing the specific structure of an integration circuit in an embodiment of the present invention is shown;

[0065] Figure 6 An embodiment of the present invention is shown Figure 5 Schematic diagram of the signal output by the integration circuit shown;

[0066] Figure 7 A flow chart showing a specific method for obtaining target reflectivity according to an embodiment of the present invention is shown;

[0067] Figure 8 A schematic diagram showing the principle of collecting pulse signal characteristics in an embodiment of the present invention is shown;

[0068] Figure 9 A specific implementation flow chart of a method for measuring target reflectivity using a laser radar according to an embodiment of the present invention is shown;

[0069] Figure 10A schematic diagram of a reflectivity mapping curve in a reflectivity calibration table according to an embodiment of the present invention is shown;

[0070] Figure 11 A schematic structural diagram of a measuring device for measuring target reflectivity using a laser radar according to an embodiment of the present invention is shown;

[0071] Figure 12 A schematic structural diagram of a laser radar in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0072] When the detection beam emitted by the LiDAR encounters a target, a portion of it is reflected back to the LiDAR by the target. The LiDAR includes a detector, which can receive the echo signal reflected by the target, and then obtain the detection information of the target by measuring the time difference between the detection beam and the echo signal. Silicon Photomultiplier (SiPM) is a new type of photoelectric detection device composed of an array of avalanche diodes (or Single Photon Avalanche Diode, SPAD) working in Geiger mode and has single-photon response characteristics. Since SiPM is usually a device manufactured based on the Complementary Metal Oxide Semiconductor (CMOS) process, it has an extremely high photoelectric gain (~10 6 ), has been applied to the field of lidar in recent years.

[0073] Many SiPMs used for laser radars have two output ports: a first output port Output1 and a second output port Output2. Signals output from the first output port Output1 or the second output port Output2 can be used to measure the reflectivity of a target.

[0074] like Figure 1A The circuit structure diagram of a three-port SiPM is shown, wherein the SiPM 0A includes multiple micro-units μ-cell connected in parallel with each other, and each micro-unit μ-cell includes a SPAD and a quenching resistor R connected in series with it. Q The cathode port Cathode is used to apply a bias voltage Vbias; the anode port Anode is used as a second output port Output2 to output an echo energy signal; and the first output port Output1 is used to output the at least one echo pulse signal.

[0075] Another example Figure 1BThe circuit structure diagram of a dual-port SiPM is shown in FIG. 1 . The difference between SiPM 0B and SiPM 0A is that a branch circuit b01 is set at the cathode port Cathode of SiPM 0B as an output branch to form the first output port Output1, and a branch circuit b02 is set at the anode port Anode to form the second output port Output2. The first branch circuit b01 is coupled to the output of the first output port Output1 through a coupling capacitor C. S0 Output echo pulse signal, the second branch circuit b02 through the integration circuit (for example Figure 5 The integrating circuit shown in FIG3 outputs the echo energy signal.

[0076] Traditionally, SiPM-based lidars measure target reflectivity based on the pulse characteristics of the echo pulse signal. For example, measuring target reflectivity based on the peak value of the echo pulse signal requires the lidar's detector signal readout circuit to be equipped with a high-speed analog-to-digital converter (ADC) with a bandwidth exceeding 200 MHz and a bit depth exceeding 10 bits. This significantly increases the lidar's power consumption and cost. Furthermore, the heat dissipation design increases the lidar's size and complexity, making it incompatible with the trend toward smaller, lower-cost, and lower-power lidars.

[0077] For example, measuring target reflectivity based on the leading edge slope and pulse width of an echo pulse signal generally requires a time-to-digital converter (TDC) in the LiDAR to sample the echo pulse signal. This is a relatively cost-effective solution for Time of Flight (ToF) measurement, making it well-suited for miniaturized LiDARs. However, the leading edge slope and pulse width of the echo pulse signal exhibit significant random jitter, making it difficult to obtain highly accurate reflectivity measurements. Furthermore, the dynamic range of the echo pulse signal is very narrow and prone to saturation (even for low-reflectivity targets at close range, the echo pulse signal intensity is sufficient to saturate the SiPM), making it virtually impossible to detect the target's reflectivity, rendering the reflectivity measurement ineffective.

[0078] In response to the above-mentioned problems existing in the measurement based on the echo pulse signal, the reflectivity can be measured based on the echo energy signal output from the second output port. This method has a large dynamic range and measurement accuracy. The laser radar transmits a detection light signal, and the detector receives the echo light signal and converts it into an electrical signal. After the flight time corresponding to the farthest target detection distance of the laser radar, the detector no longer receives the echo light signal reflected by the detection light signal. The total time that the detector receives the echo light signal corresponding to the detection light signal can be called the detection window. Within the detection window, the detection light signal may be reflected by only one object, and the detector receives the echo light signal reflected by the object, that is, a single target echo or a single event; the detection light may also be reflected by multiple different objects, so that the detector receives the echo light signals reflected by multiple objects respectively, that is, a multi-target reflection echo, or called multiple echoes or multiple events.

[0079] Research has found that due to the long coverage period of the echo energy signal output from the second output port, the echo signals of multiple targets overlap and cannot be distinguished, making it impossible to measure the reflectivity of each target corresponding to multiple echoes. In addition, the reflectivity values ​​measured in the case of multiple echoes are uncertain and easily drift due to the accumulation of energy from multiple echoes, which also has some limitations.

[0080] However, when LiDAR is used in intelligent driving, it is easy to encounter some multi-echo scenes. Figures 2A to 2C The following is a schematic diagram of several typical multi-echo scenarios in the laser radar detection process. In one scenario, a laser radar light emitting unit, such as a laser, may emit a detection beam that simultaneously illuminates two objects in front and behind. Figure 2A As shown in the figure, the detection beam s1 emitted by the laser radar A is respectively irradiated on the target objects T1 and T2 at different distances from the laser radar A, and the echoes r1 and r2 reflected by the two target objects T1 and T2 are received. In another scenario, the detection beam emitted by the laser radar may encounter a translucent object. In this case, part of the detection beam will be reflected back by the translucent object, and the other part will pass through the translucent object and irradiate another object and then be reflected back by the translucent object. Figure 2BAs shown, the detection beam s2 emitted by the laser radar A first irradiates the transparent or translucent target object T3 (such as glass), and the target object T3 will reflect the echo r3 to the laser radar A. At the same time, part of the detection beam s2 will pass through the target object T3 and irradiate the target object T4. The echo r4 reflected by the target object T4 is transmitted to the laser radar A through the target object T3. Another scenario is that in rainy, snowy, dusty and other weather conditions, part of the detection beam emitted by the laser radar will be scattered back to the laser radar by raindrops, snow, dust, etc., and the other part will be scattered to the target object and reflected back to the laser radar by the target object. Figure 2C As shown, the detection beam s3 emitted by the laser radar A is irradiated on the raindrop D0 and scattered. A part of it will be reflected back to the laser radar A as the echo signal r5, and the other part will be scattered to the target object T5. The echo r6 reflected by the target object T5 reaches the laser radar.

[0081] In summary, the target reflectivity measurement method currently used by lidar is difficult to achieve reflectivity measurement of multi-echo targets within the ranging range. However, for fields where lidar is widely used, such as intelligent driving and robotics, multi-echo scenarios are widespread. Therefore, how to achieve the recognition and detection of multi-echo targets within the ranging range is an urgent problem to be solved.

[0082] To this end, embodiments of the present invention respectively obtain at least one echo pulse signal and an echo energy signal output by the detector after receiving an echo of the probe beam reflected by at least one target, and then determine the proportion of the energy of the echo reflected by the at least one target in the echo energy signal based on the at least one echo pulse signal, thereby obtaining the reflectivity of at least one target. Using the embodiments of the present invention, on the one hand, because the echo energy signal is suitable for representing all echo energies received by the detector within the detection window, and on the other hand, the proportion of the energy of the echo reflected by the at least one target in the echo energy signal can be determined based on the at least one echo pulse signal, the reflectivity of all targets within the detection window can be obtained, thereby achieving reflectivity measurement of multiple echo targets within the ranging range and improving the accuracy and completeness of target reflectivity measurement.

[0083] In the embodiment of the present invention, the detector used can be a SiPM, or a photodiode (PD), PIN PD, SPAD or other photoelectric detection device. The embodiment of the present invention does not limit the specific device type of the detector, as long as the detection device can detect the echo of the detection light beam reflected by at least one target, and can output the echo pulse signal and echo energy signal of the at least one target based on the echo.

[0084] In order to enable those skilled in the art to better understand the inventive concepts, technical principles and advantages of the embodiments of the present invention and to better implement the present invention, the following is a detailed description with reference to some specific application examples in conjunction with the accompanying drawings.

[0085] Reference Figure 3 The flowchart of the method for measuring target reflectivity by a laser radar is shown. In an embodiment of the present invention, the following method can be used to measure the target reflectivity.

[0086] S01, respectively acquiring at least one echo pulse signal and an echo energy signal output by the detector after receiving an echo of a detection beam reflected by at least one target.

[0087] In a specific implementation, the at least one echo pulse signal may be acquired through a first output port of the detector, and the echo energy signal may be acquired through a second output port of the detector.

[0088] As a specific example, if the detector is a SiPM, refer to Figure 1A , a coupling capacitor CF corresponding to each micro unit μ-cell can be set in the SiPM. The original photocurrent output by the SPAD is AC coupled through the coupling capacitor CF with a small time constant (for example, a few nanoseconds) to generate a voltage signal as the at least one echo pulse signal, such as Figure 4A As shown, its pulse width W A Maybe just a few nanoseconds.

[0089] The echo energy signal is suitable for representing all echo energies received by the detector within a detection window.

[0090] In some embodiments of the invention, the echo energy signal can be determined based on the integral of the echo electrical signal amplitude over time. During the measurement process, the laser radar can output a series of long-duration pulse signals through the second output port of the detector, such as Figure 4B As shown, its pulse width W B , which may be more than one hundred nanoseconds. The long-time pulse signal output by the second output port has rich DC components, can well reflect the size of the echo energy, and has a large dynamic range.

[0091] In order to obtain the echo energy signal, the second output port of the detector, for example Figure 1B The second output port Output2 of the SiPM is provided with an integration circuit to output the echo energy signal. In a specific implementation, the echo electrical signal can be at least one of photocurrent, photovoltage, and the number of detected photons.

[0092] Reference Figure 5The schematic diagram of a specific integration circuit is shown. For example, a SPAD operates in Geiger mode under reverse bias +Vs. After the SPAD is triggered by a photon, the cathode output current pulse is integrated by an RC circuit consisting of a first resistor R1 and a capacitor C. This is then converted by an operational amplifier OA into a voltage signal V, which is then sampled by a second ADC (e.g., a low-speed ADC). The resulting integrated signal can serve as the echo energy signal. After integration within a detection window, switch K can be closed once to reset the integrated charge on capacitor C to zero.

[0093] In the above example, since a cumulative integration method is adopted, the measurement error caused by the single pulse jitter can be significantly reduced, and the measurement accuracy of the target reflectivity can be improved.

[0094] In a specific implementation, the integration circuit integrates all echo pulses within a preset time. For example, if the laser radar emits m pulses each time a ToF measurement is made, the echo pulse signal after being reflected by an object also includes m pulses. After the SiPM receives these m pulse signals, it can use Figure 5 The integration circuit shown outputs the total current integral of these m pulses as the echo energy signal. If the detection light is reflected by n objects respectively, the SiPM will receive m*n pulses in the detection window. If the preset time is set to the total time of the entire detection window, it can be obtained by Figure 5 The integration circuit shown outputs the total current integral of these m*n pulses.

[0095] Reference Figure 6 Schematic diagram of the output signal of the integration circuit, in this embodiment, m = 4. If the echo pulse signal output by the first output port of the detector is PL0, the corresponding second output port is integrated by the integration circuit to obtain the photocurrent integral signal IL0.

[0096] In a specific implementation, considering the influence of ambient light on the detection results, the ambient light energy signal output by the detector when receiving ambient light can be obtained, and the difference between the energy signal received by the detector in the detection window and the ambient light energy signal can be used as the echo energy signal.

[0097] In specific applications, due to differences in specific weather conditions or geographical conditions, the ambient light may also vary greatly. In order to more realistically reflect the impact of different ambient light on the target reflectivity, corresponding ambient light energy parameters can be set for different ambient light conditions.

[0098] S02: Determine, based on the at least one echo pulse signal, a proportion of the energy of the echo reflected by the at least one target in the echo energy signal to obtain a reflectivity of the at least one target.

[0099] In an embodiment of the present invention, by fusing the information of the echo pulse signal and the echo energy signal, one or more targets corresponding to the target reflected echo can be identified, and the proportion of the target reflected echo corresponding to each target in the echo energy signal can be determined, thereby obtaining the reflectivity of each target, thereby realizing the reflectivity measurement of multiple echo targets within the ranging range.

[0100] In specific implementations, the above embodiments may be further expanded or optimized according to specific needs and differences in specific application environments.

[0101] For step S02, an optional example is shown below. Figure 7 The flowchart of the specific method for obtaining the target reflectivity shown may specifically include the following measurement process.

[0102] S021, respectively collecting signal features corresponding to the at least one echo pulse signal and the echo energy signal to obtain corresponding pulse signal features and energy signal features.

[0103] In a specific implementation, a signal collector can be used to collect signal characteristics of the echo pulse signal and the echo energy signal respectively to obtain the signal characteristics corresponding to the at least one echo pulse signal and the echo signal characteristics corresponding to the echo energy signal. For the convenience of description, they are referred to as pulse signal characteristics and energy signal characteristics respectively below.

[0104] For example, a first signal collector is used to sample the at least one echo pulse signal to obtain pulse signal characteristics; a second signal collector is used to sample the echo energy signal to obtain energy signal characteristics. As an optional example, the first signal collector may be an ADC (hereinafter referred to as the first ADC) or a time-dependent digital timer (TDC); the second signal collector may also be an ADC, and for purposes of distinction, may be referred to as a second ADC. The second ADC may be identical to the first ADC, or may differ in structure, parameters, and other aspects, as long as it meets the required sampling requirements.

[0105] The digital sampling characteristics of the corresponding signal can be obtained through the ADC or TDC. In a specific implementation, the pulse signal characteristics can be one or more of the peak value, pulse leading edge slope, pulse trailing edge slope, pulse threshold pulse width and pulse coverage area of ​​the at least one echo pulse signal.

[0106] Reference Figure 8The schematic diagram of the principle of collecting pulse signal characteristics is shown. For ease of understanding, only one pulse is detected as an example. It can be understood that in actual applications, there may be multiple pulses, and the pulse signal characteristics of each pulse can be determined in the same way.

[0107] Continue to refer to Figure 8 Assume that two pulse thresholds are set, namely low threshold L0 and high threshold H0, and the peak value of pulse m0 is detected to be P0. The time of pulse m0 at low threshold L0 is leading edge time t1 and trailing edge time t4, and at high threshold H0 is leading edge time t2 and trailing edge time t3. Then the peak value of echo pulse m0 can be obtained as P0. The leading edge slope k1 is the difference between leading edge time t2 corresponding to the high threshold and leading edge time t1 corresponding to the low threshold, that is, k1=t2-t1; the trailing edge slope k2 is the difference between trailing edge time t3 corresponding to the high threshold and trailing edge time t4 corresponding to the low threshold, that is, k2=t3-t4. Low threshold pulse width W L =t4-t1, high threshold pulse width W H =t3-t2.

[0108] In a specific implementation, one or more of the above parameters can be used as the pulse signal characteristics of the at least one echo pulse signal. As an optional example, a first ADC can be used to sample the peak value of the echo pulse as the pulse signal characteristic. In a specific application, a high-speed, medium-speed, or low-speed ADC can be configured in the signal readout circuit of the detector as the first ADC. As another optional example, the pulse signal characteristics specifically include the echo pulse leading edge slope and the threshold pulse width (including at least one of a high threshold pulse width and a low threshold pulse). The at least one echo signal can be sampled using a TDC to obtain the echo pulse leading edge slope and pulse width as the pulse signal characteristics.

[0109] For example, if you use Figure 1B The SiPM shown is used as a detector, and the at least one echo pulse signal can be obtained through its first output port Output1. The first output port Output1 can output the response of each photosensitive element SPAD to the optical signal. As the at least one echo pulse signal, the pulse signal characteristics can be obtained by setting a first ADC or TDC at the first output port Output1 and sampling.

[0110] S022. Determine, based on the pulse signal characteristics, whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo. When it is determined that the echo received by the detector is a single-target reflection echo, execute step S023; when it is determined that the echo received by the detector is a multi-target reflection echo, execute step S024.

[0111] In specific implementations, to avoid inter-channel interference, each channel of a lidar emits a set of laser pulses from its transmitter (e.g., a laser) during measurement. For ease of description, this is referred to as a transmitted pulse group. In some specific examples, the encoding of the transmitted pulse group is performed by encoding the time interval between two adjacent pulses. Accordingly, only when the encoding of the echo pulse signal received by the detector of that channel (e.g., the time interval between adjacent pulses in a plurality of echo pulses) matches the encoding of the transmitted pulse group for that channel, is the target detected by the echo signal identified as a real target, and the reflectivity of the corresponding target can then be measured based on the echo signal data.

[0112] Therefore, in some embodiments of the present invention, by determining the number of pulse groups in the at least one echo pulse signal that conform to the coding of the transmitted pulse group, the number of real targets included can be determined. Therefore, as an optional example, the number of pulse groups in the at least one echo pulse signal that conform to the coding of the transmitted pulse group can be determined first, and then, based on the number of pulse groups, it can be determined whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

[0113] Considering the various optical and electrical noises present in the operating environment of a lidar detector, to reduce interference from these noise pulses, as an optional example, an echo pulse whose amplitude exceeds a preset amplitude threshold within the at least one echo pulse signal can be selected as the echo pulse corresponding to the true target for subsequent target reflectivity measurement. In this case, only echo pulses output by the detector whose amplitude exceeds the preset amplitude threshold are identified as true target echo pulses, further improving measurement accuracy.

[0114] In a specific implementation, taking the above two factors into comprehensive consideration, only when the amplitude of the at least one echo pulse signal exceeds the preset amplitude threshold and conforms to the encoding of the transmitted pulse group, is it considered to be the echo pulse signal corresponding to the echo reflected by the real target.

[0115] In some optional examples, an echo pulse with an amplitude exceeding a preset amplitude threshold can be first selected from the at least one echo pulse signal, and then the number of pulse groups that meet the coding of the transmitted pulse group can be determined from the echo pulses exceeding the preset amplitude threshold, and based on the number of pulse groups, it can be determined whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

[0116] In other optional examples, an echo pulse signal that conforms to the coding of the transmitted pulse group can be first selected from the at least one echo pulse signal, and then an echo pulse whose amplitude exceeds a preset amplitude threshold can be selected from the echo pulse signals that conform to the coding of the transmitted pulse group, and the number of pulse groups that conform to the coding of the transmitted pulse group can be determined. Based on the number of pulse groups, it can be determined whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

[0117] S023: Determine the reflectivity of the single target according to the energy signal characteristics.

[0118] S024: Obtain the reflectivity of each target according to the proportion of the energy of the reflected echo of each target in the echo energy signal.

[0119] As some optional examples, the reflected echo signal characteristics corresponding to each target and their sum can be obtained based on the pulse signal characteristics, and the proportion of the echo signal characteristics of each target in the sum can be used as the proportion of the energy of the reflected echo of each target in the echo energy signal. Then, the reflectivity of each target can be obtained according to the proportion of the energy of the reflected echo of each target in the echo energy signal.

[0120] In specific implementations, the embodiments of the present invention do not limit the specific form of the echo signal characteristics of the reflected echo signals corresponding to each target; as long as they can reflect the characteristics of the reflected echo corresponding to each target, they can be used. In some optional examples, the echo signal characteristics of the reflected echo signals corresponding to each target can be one or more of the following: pulse peak value, pulse leading edge slope, pulse trailing edge slope, pulse threshold pulse width, pulse coverage area, etc. The above parameters can be obtained by sampling a signal acquisition device such as an ADC or TDC through the specific sampling steps in the aforementioned steps. For details, please refer to the description of the aforementioned embodiments.

[0121] The following briefly describes the target reflectivity detection principle of the above embodiment:

[0122] Since the pulse signal characteristics obtained based on the echo pulse signal output by the detector after receiving the target reflection can reflect the echo light intensity, and since the echo pulse signal has the characteristic of narrow pulse width, it is easy to distinguish echoes from different targets based on the pulse signal characteristics. Therefore, the type of echo received by the detector can be determined based on the pulse signal characteristics, whether it is a single-target reflection echo or a multi-target reflection echo. Then, when it is determined that the echo received by the detector is a single-target reflection echo, the reflectivity of the single target can be determined based on the energy signal characteristics; when it is determined that the echo received by the detector is a multi-target reflection echo, the reflectivity of each target is obtained based on the proportion of the energy of each target reflection echo in the echo energy signal, thereby accurately measuring the true reflectivity of different targets within the entire ranging range. If applied to intelligent driving, it can provide a reliable basis for intelligent decision-making such as intelligent driving and ensure driving safety.

[0123] In order to enable those skilled in the art to better understand and implement the target reflectivity measurement method in the embodiment of the present invention, the following is an example introduction through a specific application scenario, referring to Figure 9 The flowchart of the method for measuring target reflectivity by a laser radar shown in FIG. 1 may specifically include the following steps:

[0124] S11, acquiring an echo pulse signal and an echo energy signal output by the detector after receiving an echo of a detection beam reflected by at least one target.

[0125] For any detection channel, all echo pulses output by the detector of the detection channel within a detection window can be obtained.

[0126] As described in the previous embodiment, the echo energy signal is suitable for representing all echo energies received by the detector within the detection window. In a specific implementation, the echo energy signal can be determined based on the time integral of the echo electrical signal amplitude. The echo electrical signal can be one or more of a photocurrent, a photovoltage, or a number of detected photons.

[0127] Taking into account the influence of ambient light, in an optional example, an ambient light energy signal output by the detector when receiving ambient light can be obtained, and the difference between the energy signal received by the detector in the detection window and the ambient light energy signal can be used as the echo energy signal.

[0128] S12, respectively collecting signal features corresponding to the echo pulse signal and the echo energy signal to obtain corresponding pulse signal features and energy signal features.

[0129] In a specific implementation, the pulse signal characteristics may specifically include the pulse amplitude, that is, the pulse peak value; the energy signal characteristics may include the integral of the echo electrical signal amplitude over time.

[0130] For example, if the photocurrent integral of the echo is used as the energy signal characteristic of the echo energy signal, assuming that the photocurrent integral of all echoes obtained by the detector within the detection window is the first photocurrent integral V Z The detector receives the ambient light output in the detection window and the photocurrent integral is the second photocurrent integral (also called the passive photocurrent integral) V B , then the photocurrent integral of the echo energy signal (also called active photocurrent integral) V d =V Z -V B Wherein, the second photocurrent integral V B The measurement is obtained when the laser radar's laser is not emitting light and the detector in the same channel is not measuring distance.

[0131] S13, determine whether the type of echo received by the detector is a single-target reflection echo or a multi-target reflection echo based on the pulse signal characteristics of the echo pulse signal. If it is determined to be a single-target reflection echo, execute step S14; if it is determined to be a multi-target reflection echo, execute step S15.

[0132] In a specific implementation, to filter out interference signals and find the echo pulse corresponding to the true target, echo pulses that meet preset conditions can be selected from all echo pulses, and the echo type can be determined based on the number of echo pulse groups that meet the preset conditions. If there is only one echo pulse group that meets the preset conditions, the measurement event is determined to be a single event, and the detector received an echo reflected from a single target. If there are two or more echo pulse groups that meet the preset conditions, the measurement event is determined to be a multiple event, and the detector received echoes reflected from multiple targets.

[0133] As an optional example, the preset condition is specifically: if the pulse amplitude of the echo pulse (i.e., the pulse peak) exceeds the preset amplitude threshold, and the time coding of the echo pulse (such as the number of pulses and the time interval between adjacent pulses) conforms to the time coding of the transmitted pulse group, it is identified as a group of echo pulses as the true echo of a target.

[0134] S14: Determine the reflectivity of the single target according to the echo energy signal.

[0135] In some embodiments of the present invention, the reflectivity of the single target may be calculated using a linear interpolation method based on the sampled echo energy signal.

[0136] Specifically, for example, the echo photocurrent signal V d , search the reflectivity calibration table stored in the laser radar, and calculate the reflectivity of the single target according to formula (1).

[0137] R = R1 + (V d0 - V d (d, R1))*(R2- R1) / ( V d (d, R2) - V d (d, R1))(1)

[0138] Wherein, R represents the reflectivity of the single target, R1 is the reflectivity value of the first standard reflective plate, R2 is the reflectivity value of the second standard reflective plate, and V d0 It is the photocurrent integral value (also called active photocurrent integral value) of the echo signal after temperature compensation and equivalent photon detection efficiency (PDE) compensation (i.e. ambient light compensation). d (d, R1) and V d (d, R2) is the active photocurrent integral value when the laser radar illuminates the first standard reflectivity plate and the second standard reflective plate at distance d. R1, R2, V d (d, R1) and V d (d, R2) can both be obtained by querying the reflectivity calibration table stored in the laser radar, and obtaining specific values ​​from the reflectivity calibration table. The first standard reflector and the second standard reflector are two standard reflectors with different reflectivities used in the calibration process.

[0139] The following is a method for obtaining the photocurrent integral value (also called active photocurrent integral value) of the echo electrical signal through temperature compensation and PDE compensation (i.e. ambient light compensation) V d0 An example method may include the following steps:

[0140] A01, through direct detection of the laser radar, the photocurrent integral V of the echo electrical signal can be obtained d , Ambient light photocurrent integral (also called passive photocurrent integral) V B , target distance d, and temperature T of the detector (such as SiPM).

[0141] A02, according to formula (2), the measured detector echo photocurrent integral V d Do temperature compensation and convert the photocurrent integral value V at the calibration temperature T0 d,T0 :

[0142] V d,T0 = V d / ( k * T + b )(2)

[0143] Among them, k and b are calibration parameters. V d,T0 is the photocurrent integral value at the calibration temperature T0, V d is the measured echo photocurrent integral of the detector.

[0144] A03, based on the ambient light photocurrent integral V B With the preset ambient light threshold V B0 The relationship between the photocurrent integral value (also called active photocurrent integral value) of the echo signal after ambient light compensation is obtained. d0 .

[0145] In an alternative example, if V B ≤ V B0 , that is, the current ambient light is weak, which may be indoors, in a tunnel or on a rainy day, then you can V d0 = V d,T0 ;like V B > V B0 , the current ambient light is strong, then you can make V d0 = V d,T0 * ( A * V d,T0 + B * V B + C ), where A, B, and C are all calibration parameters. As a specific example, V B0 The value is 200mV, which is understandable. V B0 Other values ​​may also be used, and the embodiment of the present invention is not limited to the specific value, as long as the accuracy of the target reflectivity measurement can be improved.

[0146] S15, fusing the echo pulse signal and the echo energy signal, and measuring and obtaining the reflectivity of each target corresponding to the multi-target reflected echo.

[0147] Specifically, first, based on the echo signal characteristics of the echo pulse signal, the echo signal characteristics of the reflected echo corresponding to each target and their sum can be obtained, and the proportion of the echo signal characteristics of each target in the total is used as the proportion of the energy of the reflected echo of each target in the echo energy signal, and the reflectivity of each target is obtained respectively.

[0148] Assume that the energy signal characteristics corresponding to the echo energy signal measured this time include: active photocurrent integral V d Since the integration time of the integration circuit of the second output port of the detector is not less than the total time of one detection, the first photocurrent integral V of all echoes in one detection is Z It can cover the echo pulse group information of all events, after deducting the ambient photocurrent integral V B Active photocurrent integration after echo photocurrent integration V d That is, the sum of the energies of the echo pulse groups of all events. Therefore, according to the proportion of the energy of each event echo in the active photocurrent integral, the photocurrent integral corresponding to each event, that is, the echo energy of each target, can be obtained, and then the reflectivity of each target can be calculated.

[0149] Specifically, assuming that the echo signal characteristics of the echo pulse signal corresponding to the i-th event are S i , S i The echo energy intensity of the i-th event can be reflected by the formula:

[0150] V di = S i * V d / sum( S i )(3)

[0151] The calculated echo energy of event i V di Substituting into formula (1), the reflectivity of the target corresponding to the i-th event can be calculated R i .

[0152] In a specific implementation, it is assumed that the echo signal characteristic of the echo pulse signal corresponding to the i-th event is S i It may include at least one of the pulse peak value, pulse leading edge slope, pulse trailing edge slope, threshold pulse width and pulse coverage area of ​​the echo pulse signal corresponding to the i-th event, but is not limited thereto.

[0153] As an optional example, the area covered by the pulse can be calculated based on the echo pulse signal, as S i , which can more accurately reflect the energy difference between strong echoes and weak echoes. In a specific implementation, the area covered by the pulse can be calculated using the pulse leading edge slope, pulse trailing edge slope, and pulse width obtained by TDC.

[0154] To facilitate better understanding and implementation by those skilled in the art, the following describes an example of the calibration process of the reflectivity calibration table stored by the laser radar in step S14. It should be understood that the following calibration process is not intended to limit the scope of protection of the present invention.

[0155] In order to use the echo energy signal to measure the target reflectivity, the laser radar can calibrate the echo energy signal before leaving the factory. The general process is as follows:

[0156] 1) Use the first standard reflectivity plate (reflectivity is R1) and the second standard reflectivity plate (reflectivity is R2) to calibrate the echo energy signal:

[0157] 1.1) Adjust the relative position of the laser radar and the standard reflectivity plate so that the laser spot of each channel of the laser radar is incident on the standard reflectivity plate, and obtain the echo photocurrent signal, or the integral signal V of the echo photocurrent. d ;

[0158] 1.2) Adjust the distance between the first standard reflectivity plate and the laser radar to obtain the integral signal V of the echo photocurrent output by the laser radar to the detector (e.g., SiPM) of the first standard reflectivity plate at different distances. d The numerical value of .

[0159] 2) According to the V measured during the calibration process d The reflectivity calibration table is generated based on the numerical relationship between the distance d, reflectivity R1, and reflectivity R2, and stored in the storage space of the laser radar to complete the calibration.

[0160] like Figure 10 The reflectivity mapping curve diagram of a reflectivity calibration table obtained by calibration is shown in the figure, according to the distance d and the feedback photocurrent integral signal V actually detected by the laser radar d By querying the distance d on the horizontal axis and the corresponding feedback photocurrent integral signal V on the vertical axis d , the target reflectivity R of the corresponding target can be found.

[0161] This specification also provides a measuring device that can correspond to the above-mentioned laser radar measurement method for measuring target reflectivity, referring to Figure 11 The schematic diagram of the structure of the measuring device for measuring the reflectivity of a target by a laser radar is shown in FIG. Figure 11 As shown, the laser radar 11A includes a detector 11B, and the measuring device 110 may include: a first signal acquisition unit 111, a second signal acquisition unit 112 and a processing unit 113, wherein:

[0162] The first signal acquisition unit 111 is adapted to acquire at least one echo pulse signal output by the detector after receiving an echo of the detection beam reflected by at least one target;

[0163] The second signal acquisition unit 112 is adapted to acquire an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target; the echo energy signal is adapted to represent all echo energies received by the detector within a detection window;

[0164] The processing unit 113 is adapted to determine a proportion of energy of the at least one target reflected echo in the echo energy signal according to the at least one echo pulse signal, and obtain a reflectivity of the at least one target.

[0165] In a specific implementation, the processing unit can be any device that can perform data processing, such as a central processing unit (CPU), a system-on-a-chip (SoC), a microcontroller unit (MCU), an application specific integrated circuit (ASIC), a complex programmable logic device (CPLD), a field programmable gate array (FPGA) or a digital signal processor (DSP).

[0166] In a specific implementation, the measurement device 110 can be integrated within the laser radar 11A. Thus, during detection, the laser radar 11A can instantly output the detected target reflectivity, enabling the measurement of the reflectivity of any target that may appear within the measurement range. The measurement device 110 can share some modules or components with the laser radar 11A. For example, the processing unit 113 can be implemented using the laser radar's inherent processor or FPGA computing device.

[0167] In a specific implementation, the first signal acquisition unit 111 can be specifically an ADC or TDC, and the second signal acquisition unit 112 can be specifically an ADC. The first signal acquisition unit 111 can be set at the first output port of the detector 11B, and the second signal acquisition unit 112 can be set at the second output port of the detector 11B.

[0168] The specific implementation, working principle, advantages, etc. of the measuring device can be found in the detailed description of the aforementioned measuring method, which will not be repeated here.

[0169] The embodiment of the present invention also provides a laser radar, referring to Figure 12 The schematic diagram of the structure of the laser radar shown in FIG. 1 shows that the laser radar 120 includes: a detector 121 and a processor 122, wherein:

[0170] The detector 121 is adapted to receive and, in response to an echo of the detection light reflected by at least one target, output at least one echo pulse signal and an echo energy signal; the echo energy signal is adapted to represent all echo energies received by the detector within a detection window;

[0171] The processor 122 is coupled to the detector 121 and is adapted to determine the proportion of energy of the at least one target reflected echo in the echo energy signal based on the at least one echo pulse signal, so as to obtain the reflectivity of the at least one target.

[0172] By using this laser radar to measure the reflectivity of a target, it is possible to measure the reflectivity of at least one echoing target within the entire range. If this laser radar is applied to intelligent driving, it can provide a reliable basis for intelligent decision-making, such as intelligent driving, and ensure driving safety.

[0173] In a specific implementation, the detector 121 can be a SiPM, or a photodiode (PD), a PIN PD, a single photon avalanche diode (SPAD), or other photoelectric detection device. The embodiment of the present invention does not limit the specific device type of the detector, as long as the detection device can detect the echo of the detection light beam reflected by at least one target, and can output the echo pulse signal and echo energy signal of the at least one target based on the echo.

[0174] In a specific implementation, the detector may specifically include: a SiPM, and the SiPM may include two output ports, wherein:

[0175] a first output port, outputting the at least one echo pulse signal;

[0176] The second output port outputs the echo energy signal through a branch circuit.

[0177] In a specific implementation, the first output port may include: a coupling capacitor; the second output port may include: an integration circuit.

[0178] For example, you can use Figure 1AThe three-port SiPM shown is used as a detector to detect the echo. In a specific implementation, the first output port Output1 can be connected to the corresponding coupling capacitor CF of each micro unit μ-cell to output the echo pulse signal, and the second output port Output2 can be coupled to the integration circuit to output the echo energy signal.

[0179] Alternatively, a dual-port SiPM can be used as a detector to measure the echo, such as Figure 1B As shown in the structural diagram of the SiPM, a branch circuit b01 can be set at the cathode port Cathode of SiPM 0B as an output branch to form a first output port Output1; a branch circuit b02 can be set at the anode port Anode to form a second output port Output2, wherein the first branch circuit b01 is coupled to the cathode port Cathode of SiPM 0B as an output branch to form a first output port Output1; and a branch circuit b02 can be set at the anode port Anode to form a second output port Output2. S0 Output echo pulse signal, the second branch circuit b02 through the integration circuit (for example Figure 5 The integrating circuit shown in FIG3 outputs the echo energy signal.

[0180] In the specific implementation, continue to refer to Figure 12 The laser radar 120 may further include: a first signal collector 123 and a second signal collector 124, wherein:

[0181] The first signal collector 123 is adapted to collect signal characteristics corresponding to the at least one echo pulse signal to obtain corresponding pulse signal characteristics;

[0182] The second signal collector 124 is adapted to collect the signal characteristics corresponding to the echo energy signal to obtain the corresponding energy signal characteristics;

[0183] The processor 122 is suitable for determining whether the type of echo received by the detector 121 is a single-target reflection echo or a multi-target reflection echo based on the pulse signal characteristics. When it is determined that the echo received by the detector 121 is a single-target reflection echo, the reflectivity of the single target is determined according to the energy signal characteristics; when it is determined that the echo received by the detector 121 is a multi-target reflection echo, the reflectivity of each target is obtained respectively according to the proportion of the energy of each target reflection echo in the echo energy signal.

[0184] As an optional example, the processor 122 is suitable for determining the number of pulse groups in the at least one echo pulse signal that conform to the coding of the transmitted pulse group; and determining, based on the number of pulse groups, whether the type of echo received by the detector 121 is a single-target reflection echo or a multi-target reflection echo.

[0185] As another optional example, the processor 122 is suitable for selecting an echo pulse whose amplitude exceeds a preset amplitude threshold in the at least one echo pulse signal before determining whether the type of echo received by the detector 121 is a single-target reflection echo or a multi-target reflection echo based on the number of the pulse groups.

[0186] In a specific implementation, the processor 122 is suitable for obtaining the echo signal characteristics of the reflected echo corresponding to each target and their sum according to the pulse signal characteristics when determining that the received echo type is a multi-target reflected echo, and taking the proportion of the echo signal characteristics of each target in the total as the proportion of the energy of the reflected echo of each target in the echo energy signal.

[0187] In a specific implementation, the first signal collector 123 may include at least one of the following:

[0188] a first analog-to-digital converter (not shown), adapted to sample the at least one echo pulse signal to obtain the pulse signal characteristics;

[0189] a time-to-digital converter (not shown), adapted to sample the echo energy signal to obtain the pulse signal characteristics;

[0190] The second signal collector 124 may include: a second analog-to-digital converter 124, adapted to sample the echo energy signal to obtain the energy signal feature.

[0191] In some embodiments of the present specification, the detector 121 includes a plurality of single-photon avalanche diodes connected in parallel, and the second analog-to-digital converter is suitable for determining the echo energy signal based on the integral of the amplitude of the echo electrical signal output by the detector over time, and the amplitude of the echo electrical signal is positively correlated with the number of single-photon avalanche diodes triggered in the detector.

[0192] In a specific implementation, the processor may be any device capable of performing data processing, such as a CPU, a SoC, an MCU, an ASIC, a CPLD, an FPGA or a DSP.

[0193] The specific working principle, achievable examples, advantages, etc. of the laser radar can be found in the specific embodiments of the aforementioned method and will not be described in detail here.

[0194] Although the embodiments of the present invention are disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for measuring target reflectivity using a laser radar, wherein the laser radar includes a detector, characterized in that: The method comprises: Respectively acquiring at least one echo pulse signal and an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target; the echo energy signal is suitable for representing all echo energies received by the detector within a detection window; Determining, according to the at least one echo pulse signal, a proportion of energy of the at least one target reflected echo in the echo energy signal to obtain a reflectivity of the at least one target, comprising: respectively collecting signal features corresponding to the at least one echo pulse signal and the echo energy signal to obtain corresponding pulse signal features and energy signal features; determining, according to the pulse signal characteristics, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo; When it is determined that the echo received by the detector is a single target reflection echo, determining the reflectivity of the single target according to the energy signal characteristics; When it is determined that the echo received by the detector is a multi-target reflected echo, the reflectivity of each target is obtained according to the proportion of the energy of the reflected echo of each target in the echo energy signal.

2. The method according to claim 1, characterized in that The determining, based on the pulse signal characteristics, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo comprises: determining the number of pulse groups in the at least one echo pulse signal that conform to the encoding of the transmitted pulse group; According to the number of the pulse groups, it is determined whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

3. The method according to claim 2, characterized in that Before determining, according to the number of the pulse groups, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo, the method further includes: An echo pulse whose amplitude exceeds a preset amplitude threshold value is selected from the at least one echo pulse signal.

4. The method according to claim 1, wherein When it is determined that the echo received by the detector is a multi-target reflected echo, the reflectivity of each target is obtained according to the proportion of the energy of the reflected echo of each target in the echo energy signal, including: Acquire the echo signal characteristics of the reflected echo corresponding to each target and their sum according to the pulse signal characteristics; The proportion of the echo signal characteristics of each target in the total is used as the proportion of the energy of the echo reflected by each target in the echo energy signal.

5. The method according to claim 4, characterized in that The echo signal characteristics of the reflected echo signals corresponding to the respective targets include at least one of the following: Pulse peak value, pulse leading edge slope, pulse trailing edge slope, pulse threshold pulse width, and pulse coverage area.

6. The method according to claim 1, characterized in that Acquiring an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target includes: Acquire an ambient light energy signal output by the detector when receiving ambient light; The difference between the energy signal received by the detector in the detection window and the ambient light energy signal is used as the echo energy signal.

7. The method according to claim 1, characterized in that The echo energy signal is determined according to the integration of the amplitude of the echo electrical signal over time.

8. The method according to claim 7, characterized in that The echo electrical signal is at least one of photocurrent, photovoltage, and number of detected photons.

9. A laser radar measuring device for measuring target reflectivity, the laser radar comprising a detector, characterized in that: The measuring device comprises: a first signal acquisition unit, adapted to acquire at least one echo pulse signal output by the detector after receiving an echo of the detection beam reflected by at least one target; a second signal acquisition unit, adapted to acquire an echo energy signal output by the detector after receiving an echo of the detection beam reflected by at least one target; the echo energy signal is adapted to represent all echo energies received by the detector within a detection window; A processing unit is suitable for determining the proportion of the energy of the at least one target reflected echo in the echo energy signal based on the at least one echo pulse signal to obtain the reflectivity of the at least one target, including: respectively collecting the signal characteristics corresponding to the at least one echo pulse signal and the echo energy signal to obtain corresponding pulse signal characteristics and energy signal characteristics; determining the type of the echo received by the detector as a single-target reflected echo or a multi-target reflected echo based on the pulse signal characteristics; when it is determined that the echo received by the detector is a single-target reflected echo, determining the reflectivity of the single target based on the energy signal characteristics; when it is determined that the echo received by the detector is a multi-target reflected echo, respectively obtaining the reflectivity of each target based on the proportion of the energy of the reflected echo of each target in the echo energy signal.

10. A laser radar, characterized in that: include: a detector adapted to receive and output at least one echo pulse signal and an echo energy signal in response to an echo of the detection light reflected by at least one target; The echo energy signal is suitable for representing all echo energies received by the detector within the detection window; a first signal collector, adapted to collect a signal feature corresponding to the at least one echo pulse signal to obtain a corresponding pulse signal feature; a second signal collector, adapted to collect signal characteristics corresponding to the echo energy signal to obtain corresponding energy signal characteristics; A processor is coupled to the detector, the first signal collector, and the second signal collector, and is adapted to determine, based on the at least one echo pulse signal, a proportion of the energy of the at least one target reflected echo in the echo energy signal to obtain the reflectivity of the at least one target, including: determining, based on the pulse signal characteristics, whether the type of the echo received by the detector is a single-target reflected echo or a multi-target reflected echo; When it is determined that the echo received by the detector is a reflection echo of a single target, the reflectivity of the single target is determined according to the energy signal characteristics; when it is determined that the echo received by the detector is a reflection echo of multiple targets, the reflectivity of each target is obtained according to the proportion of the energy of the reflection echo of each target in the echo energy signal.

11. The laser radar according to claim 10, characterized in that The processor is adapted to determine the number of pulse groups in the at least one echo pulse signal that conform to the encoding of the transmitted pulse group; and determine, based on the number of pulse groups, whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo.

12. The laser radar according to claim 11, characterized in that The processor is adapted to select an echo pulse whose amplitude exceeds a preset amplitude threshold in the at least one echo pulse signal before determining whether the type of the echo received by the detector is a single-target reflection echo or a multi-target reflection echo based on the number of the pulse groups.

13. The laser radar according to claim 10, characterized in that The processor is suitable for obtaining the echo signal characteristics of the reflected echo corresponding to each target and their sum according to the pulse signal characteristics when determining that the received echo type is a multi-target reflected echo, and taking the proportion of the echo signal characteristics of each target in the total as the proportion of the energy of the reflected echo of each target in the echo energy signal.

14. The laser radar according to claim 10, characterized in that The first signal collector includes at least one of the following: a first analog-to-digital converter, adapted to sample the at least one echo pulse signal to obtain the pulse signal characteristics; a time-to-digital converter, adapted to sample the echo pulse signal to obtain the pulse signal characteristics; The second signal collector includes: The second analog-to-digital converter is adapted to sample the echo energy signal to obtain the energy signal characteristics.

15. The laser radar according to claim 14, characterized in that The detector includes multiple single-photon avalanche diodes connected in parallel, and the second analog-to-digital converter is suitable for determining the echo energy signal based on the integration of the amplitude of the echo electrical signal output by the detector over time, and the amplitude of the echo electrical signal is positively correlated with the number of single-photon avalanche diodes triggered in the detector.

16. The laser radar according to claim 15, characterized in that The detector includes a silicon photomultiplier tube, which includes two output ports, wherein: a first output port, outputting the at least one echo pulse signal; The second output port outputs the echo energy signal through a branch circuit.

17. The laser radar according to claim 16, characterized in that The first output port includes a coupling capacitor; the second output port includes an integration circuit.

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