Dynamic threshold adjustment method for siPM receiver and lidar and lidar

Abstract

The present disclosure provides a laser radar, comprising: a plurality of receiving devices, which can receive incident light and generate electrical signals; and a control unit, coupled with the plurality of receiving devices, and can obtain the intensity of the incident light according to the electrical signals, wherein the control unit is configured to: form a gray scale map according to the intensity of the incident light obtained by the plurality of receiving devices at multiple angles, wherein each pixel in the gray scale map corresponds to the intensity of the incident light obtained by the receiving device at at least one angle.

Description

Technical Field

[0001] This application relates generally to the field of optoelectronic technology, and in particular to a dynamic threshold adjustment method that can be used in SiPM receivers, a dynamic threshold adjustment method that can be used in lidar, and lidar. Background Technology

[0002] LiDAR (LiDAR) is a general term for active laser detection sensor devices. Its working principle is roughly as follows: The LiDAR transmitter emits a laser beam. When the laser beam encounters an object, it undergoes diffuse reflection and returns to the laser receiver. The radar module calculates the distance between the transmitter and the object by multiplying the time interval between the transmitted and received signals by the speed of light and then dividing by 2. Depending on the number of laser beams, there are typically single-line LiDAR, 4-line LiDAR, 8 / 16 / 32 / 64-line LiDAR, etc. One or more laser beams are emitted vertically at different angles and scanned horizontally to detect the three-dimensional contour of the target area. Multiple measurement channels (lines) are equivalent to multiple scanning planes with different tilt angles; therefore, the more laser beams in the vertical field of view, the higher the vertical angular resolution and the greater the density of the laser point cloud.

[0003] Laser receivers can use a variety of components to sense the echo, such as avalanche diodes or silicon photomultipliers (SiPMs).

[0004] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0005] To address at least one deficiency in the prior art, this disclosure provides a dynamic threshold adjustment method for a SiPM receiver, comprising:

[0006] The incident light is received by the SiPM receiver;

[0007] To obtain the intensity of the incident light; and

[0008] The threshold of the SiPM receiver is adjusted according to the intensity of the incident light.

[0009] According to one aspect of this disclosure, obtaining the intensity of the incident light includes: counting pulses generated by the incident light that are higher than the current value based on the current value of the threshold of the SiPM receiver, obtaining an incident light count value, which characterizes the intensity of the incident light.

[0010] According to one aspect of this disclosure, adjusting the threshold of the SiPM receiver includes adjusting the amount proportional to the difference between the incident light count value and an optimal count value.

[0011] This disclosure also provides a dynamic threshold adjustment method for use in lidar, wherein the lidar includes multiple SiPM receivers that can sense incident light at multiple angles, and the dynamic threshold adjustment method includes:

[0012] The incident light is received at the current angle using a SiPM receiver;

[0013] To obtain the intensity of the incident light;

[0014] The threshold of the SiPM receiver at the next angle is adjusted according to the intensity of the incident light.

[0015] According to one aspect of this disclosure, obtaining the intensity of the incident light includes: counting pulses of the incident light that are higher than the current value generated by the incident light through the SiPM receiver at the current angle, thereby obtaining an incident light count value.

[0016] According to one aspect of this disclosure, adjusting the threshold of the SiPM receiver at the next angle includes adjusting the amount proportional to the difference between the incident light count value and an optimal count value.

[0017] According to one aspect of this disclosure, the dynamic threshold adjustment method further includes: forming a grayscale image based on the intensity of incident light obtained by the plurality of SiPM receivers at multiple angles, wherein each pixel in the grayscale image corresponds to the intensity of incident light obtained by one of the SiPM receivers at one of the angles.

[0018] According to one aspect of this disclosure, the step of receiving incident light at the current angle via a SiPM receiver is performed when the SiPM receiver is not performing ranging.

[0019] This disclosure also provides a lidar, including:

[0020] Multiple SiPM receivers, each capable of receiving incident light and generating electrical pulses, have a corresponding threshold.

[0021] A signal processing device, coupled to the SiPM receiver and receiving the electrical pulse, outputs the electrical pulse when the electrical pulse exceeds a threshold value of the SiPM receiver; and

[0022] The control unit is coupled to the plurality of SiPM receivers and can obtain the intensity of the incident light according to the electrical pulse, and adjust the threshold of the SiPM receiver according to the intensity of the incident light.

[0023] According to one aspect of this disclosure, obtaining the intensity of the incident light includes: counting pulses generated by the incident light that are higher than the current value, to obtain an incident light count value.

[0024] According to one aspect of this disclosure, the lidar has multiple detection angles, and adjusting the threshold of the SiPM receiver includes: adjusting the threshold of the SiPM at the next detection angle using an adjustment amount proportional to the difference between the incident light count value and an optimal count value.

[0025] According to one aspect of this disclosure, the control unit is configured to form a grayscale image based on the intensity of incident light obtained by the plurality of SiPM receivers at a plurality of angles, wherein each pixel in the grayscale image corresponds to the intensity of incident light obtained by one of the SiPM receivers at one of the angles.

[0026] According to one aspect of this disclosure, the step of receiving incident light at the current angle via a SiPM receiver is performed when the SiPM receiver is not performing a measurement. Attached Figure Description

[0027] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:

[0028] Figure 1 A schematic diagram of the echo signal and ambient noise of the SiPM receiver is shown;

[0029] Figure 2 A dynamic threshold adjustment method for a SiPM receiver according to one embodiment of this application is shown;

[0030] Figure 3A and 3B The following diagram illustrates the signal pulses generated by the SiPM according to an embodiment of this application;

[0031] Figure 4 A schematic diagram showing multiple lasers arranged, for example, roughly in a vertical direction;

[0032] Figure 5 A dynamic threshold adjustment method for lidar according to an embodiment of the present disclosure is shown;

[0033] Figure 6 The image shows a grayscale image formed by multiple SiPM detectors;

[0034] Figure 7 A schematic diagram of the transmitter and receiver of a lidar is shown; and

[0035] Figure 8A lidar according to an embodiment of the present disclosure is shown. Detailed Implementation

[0036] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure. Therefore, the drawings and description are to be considered exemplary in nature and not restrictive.

[0037] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0038] The preferred embodiments of this disclosure are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0039] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or connections that allow for communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0040] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0041] In lidar, various components can be used as laser receivers to sense radar echo signals, such as avalanche diodes (SPADs) or silicon photomultipliers (SiPMs). The basic structural unit of a SiPM consists of an avalanche photodiode (SPAD) with single-photon detection capability and a series quenching resistor. After receiving a photon, the SiPM induces an electron with a certain probability, triggering the avalanche effect. The specific process of converting the optical signal into an electrical signal is as follows: when a photon is incident on a SPAD operating in Geiger mode, a photoelectron is generated with a certain probability. This electron induces an avalanche effect in the depletion region, producing a constant electrical pulse output. At this point, the pixel is said to be in an ignition state.

[0042] After an avalanche, the SPAD is in a quenched state, and other incident photons can no longer trigger an avalanche effect. Therefore, each pixel can only provide the "presence" or "absence" information of photons. Since the output ports are connected in parallel, the electrical pulses output by each pixel are superimposed into a giant pulse. By measuring the charge or amplitude of the giant pulse, the number of ignited pixels can be calculated, and the distribution characteristics of the incident photons, i.e., the echo characteristics, can be inferred.

[0043] Silicon photomultipliers (SiPMs) possess a spectral response range from near-ultraviolet to near-infrared, exhibiting strong photonics capabilities and high single-photon level sensitivity. When SiPMs are used as receivers in lidar systems, background light (primarily referring to random noise generated by ambient light reflecting off obstacles and entering the detector) can increase the noise floor of the SiPM output. Figure 1 The diagram shows an echo. If the comparator threshold is too low, a large number of noise pulses will enter the subsequent devices (such as TDC) used to analyze the signal and generate the echo. However, the processing capacity of the devices is limited. In order to avoid the signal pulses being overwhelmed by a large amount of noise, the comparator threshold needs to be increased.

[0044] However, at the same time, it's necessary to control the threshold to be as low as possible to maximize the detection range. Furthermore, different weather conditions and target reflectivity will lead to varying levels of background noise or ambient noise. Therefore, the performance of the dynamic threshold adjustment method has a significant impact on the ranging performance of lidar.

[0045] Figure 2 A dynamic threshold adjustment method 100 for a SiPM receiver according to one embodiment of this application is illustrated. Reference is made below. Figure 2 Detailed description.

[0046] In step S101, the incident light is received by the SiPM receiver.

[0047] The incident light received by the SiPM receiver can be the echo signal of the lidar (i.e., the reflected laser signal that returns to the SiPM receiver after being reflected by the laser beam emitted by the lidar's laser emitter and reflected by an external object), or it can be the background light of the lidar's environment, such as sunlight, or it can include both the echo signal and the background light. All of these are within the protection scope of this disclosure.

[0048] In step S102, the intensity of the incident light is obtained.

[0049] The intensity of the incident light can be characterized in various ways, such as the amplitude of the current and / or voltage generated by the incident light, or the number of pulses. According to one embodiment, the intensity of the incident light can be characterized by the number of electrical pulses generated by the incident light. Those skilled in the art can also conceive of other ways to characterize the intensity of the incident light, all of which are within the scope of this disclosure.

[0050] Furthermore, those skilled in the art will understand that the intensity of the incident light can be obtained not only from the electrical pulse generated by the SiPM receiver, but also from other means, such as from another photoelectric sensor specifically designed to measure the intensity of incident light or ambient light, all of which are within the scope of this disclosure.

[0051] In step S103, the threshold Th of the SiPM receiver is adjusted according to the intensity of the incident light.

[0052] Based on the intensity of the incident light obtained in step S102, the threshold Th of the SiPM receiver can be dynamically adjusted in step S103. For example, when the incident light intensity is too high, such as when the SiPM receiver is in a strong sunlight environment, the threshold Th of the SiPM receiver can be increased to prevent a large number of noise pulses from entering the subsequent devices or circuits used to generate echoes for signal analysis, thus preventing the signal pulses from being overwhelmed by a large amount of noise. Conversely, when the incident light intensity is low, such as when the SiPM receiver is detecting in a dark environment at night, the threshold Th of the SiPM receiver can be decreased to ensure that the normal echo signal is not filtered out and can enter the subsequent devices or circuits for signal analysis and echo generation.

[0053] After adjusting the threshold for the SiPM receiver, subsequent devices, circuits, or software can use this adjusted threshold to filter out noise or background light signals. For example, in the electrical pulses generated by the incident light in the SiPM receiver, those pulses with amplitudes equal to or higher than the adjusted threshold are identified as valid echo signals; while those pulses with amplitudes lower than the adjusted threshold are identified as noise or background light signals and directly filtered out, improving the signal-to-noise ratio of the lidar, effectively analyzing the echo signals, and increasing the accuracy and reliability of radar ranging.

[0054] The method 100 described above can be executed continuously to dynamically adjust the threshold of the SiPM receiver, ensuring that the threshold remains within a reasonable range. Furthermore, in the case of an array with multiple SiPM receivers, the thresholds of each SiPM receiver can be adjusted individually or as a whole. For example, in the case of individual adjustment, steps S101, S102, and S103 are executed for each SiPM receiver separately. In the case of overall adjustment, the thresholds of all SiPM receivers can be dynamically adjusted, for example, by obtaining the intensity of the incident light from one of the SiPM receivers. In the latter approach, the incident light intensity of one SiPM receiver is used to represent the incident light intensity of the other SiPM receivers; although the accuracy is slightly lower, the processing speed is faster and the structure is simpler.

[0055] According to one embodiment of this disclosure, the intensity of incident light is characterized by counting pulses received by a SiPM receiver. For each SiPM receiver, an initial value can be set, which can be any value. This initial value is used as the current value of a threshold, and the pulses generated by the incident light are compared with this current value. Pulses higher than the current threshold value are counted to obtain an incident light count value (or incident light intensity count value) NoiseCount, which can be used to characterize the intensity of the incident light.

[0056] For example, Figure 3A As shown, the incident light received by the SiPM receiver includes both the lidar echo signal and the background light signal. During one TOF cycle, the incident light generates a total of eight pulse signals on the SiPM receiver, one of which corresponds to the lidar echo signal, and the other seven pulse signals correspond to the background light signal. The current threshold value of the SiPM receiver is as follows: Figure 3A As described, all eight pulse signals are higher than the current value of the threshold. 8 can be used as the incident light count value (NoiseCount), or the echo signal from the lidar can be excluded, and 7 can be used as the incident light count value (NoiseCount) to characterize the intensity of the incident light. Those skilled in the art can adopt different schemes as needed. When distinguishing between the pulse signals generated by the background light and those generated by the echo, amplitude can be used for judgment. Generally, the amplitude of the pulse signals generated by the echo is higher than that of the pulse signals generated by the background light. Therefore, an echo signal threshold can be preset, and the pulses generated by the incident light can be compared with this echo signal threshold. Pulses higher than this echo signal threshold are echo pulses, and those lower are pulses generated by the background light. Those skilled in the art can also devise other distinction methods.

[0057] Figure 3B In the scenario shown, the incident light received by the SiPM receiver includes only the background light signal, and the number of pulses above the current threshold value is five. Therefore, 5 is used as the incident light count value NoiseCount to characterize the intensity of the incident light.

[0058] According to a preferred embodiment of this disclosure, when adjusting the threshold of the SiPM receiver, the adjustment amount ADJ is proportional to the difference between the incident light count value NoiseCount and an optimal count value OptimumCount, thereby enabling adjacent measurement points to match the background noise of the target. The optimal count value OptimumCount refers to the count value required to accurately reflect the intensity of the background light. Those skilled in the art can set this optimal count value OptimumCount as needed. The optimal count value is determined experimentally; for example, it can be set to 3. The adjustment amount ADJ is calculated using the following formula 1.

[0059] ADJ∝(NoiseCount-OptimumCount) (Formula 1)

[0060] Furthermore, it will be readily understood by those skilled in the art that the adjustment amount ADJ can be positive or negative.

[0061] After obtaining ADJ, the threshold of the SiPM receiver is further corrected using Equation 2.

[0062] Th n+1 =Th n +ADJ (Formula 2)

[0063] Among them Th n It is the current value of the threshold of the SiPM receiver, Th n+1 It is the threshold of the modified SiPM receiver, such as the decision threshold used for the next measurement.

[0064] The transmitting end of a lidar system can have multiple lasers emitting laser beams; the following explanation uses a system with 64 lasers as an example. The receiving end of the lidar system has 64 SiPM detectors to receive the echo signals, also known as 64 receiving channels. However, this disclosure does not impose any restrictions on the number, arrangement, or correspondence of the lasers and detectors; they can be selected and arranged according to requirements.

[0065] Sixty-four lasers, for example, are arranged roughly vertically, and the emitted laser beams form a series of scanning lines, such as... Figure 4 As shown, at least a portion of the laser's output beam is illustrated, enabling the lidar to scan vertically. Multiple scan lines form a scanning surface. After completing a scan on one surface, the lidar's optomechanical rotor rotates a certain angle (e.g., 0.1 degrees) in the horizontal plane to complete the scan on the next surface. The optomechanical rotor continues to rotate, thus achieving a 360-degree horizontal scan.

[0066] Figure 5 A dynamic threshold adjustment method 200 for use with a lidar according to an embodiment of the present disclosure is illustrated, wherein the lidar includes, for example, a plurality of SiPM receivers. As the lidar or its optomechanical rotor rotates, each SiPM receiver can sense incident light at multiple angles, for example, sensing every 0.1 degrees in the horizontal direction, achieving a 360-degree horizontal scan. Reference is made below. Figure 5 The dynamic threshold adjustment method 200 is described.

[0067] In step S201, the incident light is received at the current angle through a SiPM receiver.

[0068] At the current rotation angle of the lidar, the incident light is received by one of the SiPM receivers. The received incident light can be either the lidar's echo signal (i.e., the laser beam emitted by the lidar's laser emitter, reflected off an external object, and returned to the SiPM receiver), or the background light of the lidar's environment, such as sunlight, or both the echo signal and the background light.

[0069] In step S202, the intensity of the incident light is obtained.

[0070] According to a preferred embodiment of this disclosure, the pulses generated by the incident light that are higher than the current threshold value at the current angle can be counted by the SiPM receiver to obtain an incident light count value. For example, for 64 SiPM receivers in a lidar system, a table can be created to record the initial threshold values ​​of the 64 channels. The initial threshold value can be any value, and the threshold for each SiPM receiver can be taken from this initial threshold value. The pulses generated by the incident light are compared with the current value, and the pulses that are higher than the current value are counted to calculate the number of electrical pulses, thereby obtaining the incident light count value (or incident light intensity count value) NoiseCount. This incident light count value can be used to characterize the intensity of the incident light.

[0071] Furthermore, those skilled in the art will understand that the intensity of the incident light can be obtained not only from the electrical pulses generated by the SiPM receiver, but also from other methods. For example, a dedicated photoelectric sensor can be installed on the lidar specifically for measuring the intensity of the incident light or background light. For all or some of the SiPM receivers on the lidar, the incident light intensity measured by this dedicated photoelectric sensor can be used to adjust the threshold of all or some of the SiPM receivers. Alternatively, the incident light intensity measured by one of the multiple SiPM receivers can be used as an approximation of the incident light intensity of the other SiPM receivers for subsequent threshold adjustment.

[0072] In step S203, the threshold of the SiPM receiver at the next angle is adjusted according to the intensity of the incident light.

[0073] According to a preferred embodiment of the present invention, when adjusting the threshold of the SiPM receiver, the adjustment amount is proportional to the difference between the incident light count value and an optimal count value, as shown in Formula 1. The specific method for adjusting the threshold is shown in Formula 2.

[0074] After adjusting the threshold for the SiPM receiver, subsequent devices, circuits, or software can use the adjusted threshold to filter out noise signals or background light. For example, in the electrical pulses generated by the SiPM receiver due to incident light, those electrical pulses with amplitudes equal to or higher than the adjusted threshold are identified as valid echo signals; while those electrical pulses with amplitudes lower than the adjusted threshold are identified as noise signals or background light signals and are directly filtered out.

[0075] The above method 100 can be executed continuously to dynamically adjust the threshold of the SiPM receiver, ensuring that the threshold remains within a reasonable range. Furthermore, since the lidar has multiple SiPM receivers, the thresholds of each SiPM receiver can be adjusted individually or as a whole. For example, in the case of individual adjustment, steps S201, S202, and S203 are executed for each SiPM receiver separately. In the case of overall adjustment, the thresholds of all SiPM receivers can be dynamically adjusted, for example, by obtaining the intensity of the incident light from one of the SiPM receivers. In the latter approach, the incident light intensity of one SiPM receiver is used to represent the incident light intensity of the other SiPM receivers. Although the accuracy is slightly lower, the processing speed is faster and the structure is simpler.

[0076] Furthermore, according to a preferred embodiment of this disclosure, a grayscale image can be formed based on the intensity of incident light obtained by the plurality of SiPM receivers at multiple angles, wherein each pixel in the grayscale image corresponds to the intensity of incident light obtained by one of the SiPM receivers at one angle. For example, the value representing the intensity of incident light obtained by one of the SiPM receivers is 7 (e.g., Figure 3A As shown (excluding the echo signal), another SiPM receiver obtained a value of 5 characterizing the incident light intensity (as shown). Figure 3B (As shown) Then a grayscale image can be formed based on the noise count of the two SiPM detectors mentioned above, such as... Figure 6 As shown, the last 64 channels can form a column of grayscale image of the complete field of view. As the lidar rotates, the grayscale data can be generated from a column to form a two-dimensional image, and then a grayscale video synchronized with the rotation frequency can be generated.

[0077] Additionally, according to one embodiment of this disclosure, method 200 further includes using the adjusted threshold as the threshold for the corresponding SiPM receiver at the next angle. For example, if the threshold of the SiPM receiver is adjusted based on the incident light intensity at the current angle of 0 degrees, and the lidar subsequently rotates to the next angle of 0.1 degrees, then the previously adjusted threshold will be used as the judgment threshold for that next angle. This process is repeated cyclically, allowing for continuous and dynamic correction of the SiPM receiver threshold. This is highly advantageous in certain situations. For example, when the lidar is in shadow on one side and exposed to sunlight on the other, this method can adjust the threshold very effectively.

[0078] Furthermore, according to one embodiment of this disclosure, the timing of step S201 can be selected to more accurately measure the background light. For example, when a SiPM receiver is not performing TOF ranging, the incident light is received at the current angle by the SiPM receiver. In this way, it can be ensured that the pulse signal generated by the SiPM receiver does not include or includes as little as possible the echo signal.

[0079] Besides the linear arrangement of the SiPM detectors, according to one embodiment of this disclosure, the laser and SiPM detectors of the lidar can have other arrangements. For example... Figure 7 As shown, the LiDAR's transmitting circuit board 703A is equipped with four sets of transmitting light sources (lasers) 703B, which are arranged in a staggered manner in the vertical direction. Figure 7 The diagram also shows a lidar receiver circuit board 704A with four sets of photoelectric sensing elements 704B, such as a SiPM receiver. Preferably, the four sets of photoelectric sensing elements 704B are arranged alternately in the vertical direction.

[0080] During actual lidar scanning, for a single scan line, the areas received by the 64 SiPMs may correspond to different background light environments. For example, the echoes received by 1-3 receivers correspond to scan areas with stronger background light, while those received by 5-8 receivers correspond to scan areas with weaker background light. In other words, if the background light is strong, there is more noise, so the threshold of the channel corresponding to the next scan surface is increased; if the background light is weak, the threshold of the channel corresponding to the next scan surface is decreased. Simultaneously, the noise counts of the two SiPM units form a grayscale image, such as... Figure 6 Finally, the 64 channels can form a column of grayscale image of the complete field of view. As the lidar rotates, the grayscale data can be generated from a column to form an image, thereby generating a grayscale video synchronized with the rotation frequency.

[0081] like Figure 8 As shown, this disclosure also relates to a lidar 300, including a plurality of SiPM receivers 301 and a control unit 303. Each SiPM receiver receives incident light and generates electrical pulses, and each SiPM receiver has a corresponding threshold. The initial value of the threshold is, for example, fixedly stored in the lidar's internal memory. The control unit 303 is coupled to the plurality of SiPM receivers 301 and can obtain the intensity of the incident light based on the electrical pulses, and adjust the threshold of the SiPM receivers according to the intensity of the incident light. Furthermore, those skilled in the art will understand that the control unit 303 and the SiPM receivers 301 can be directly connected or indirectly connected through other circuits or devices, all of which are within the scope of this disclosure.

[0082] According to one embodiment of this disclosure, the lidar further includes a signal processing device coupled to the SiPM receiver and receiving the electrical pulse, and outputting the electrical pulse when the electrical pulse is greater than a threshold of the SiPM receiver.

[0083] According to a preferred embodiment of this disclosure, obtaining the intensity of the incident light includes: counting pulses generated by the incident light that are higher than the current value, and obtaining an incident light count value.

[0084] According to a preferred embodiment of this disclosure, the lidar has multiple detection angles or multiple detection orientations. Adjusting the threshold of the SiPM receiver includes: using the difference between the incident light count value and an optimal count value as the adjustment amount to adjust the threshold of the SiPM at the next detection angle, as shown in Formulas 1 and 2 above, which will not be repeated here.

[0085] According to a preferred embodiment of the present disclosure, the control unit 303 is configured to form a grayscale image based on the intensity of incident light obtained by the plurality of SiPM receivers at multiple angles, wherein each pixel in the grayscale image corresponds to the intensity of incident light obtained by one of the SiPM receivers at one of the angles.

[0086] According to a preferred embodiment of this disclosure, the step of receiving incident light at the current angle via a SiPM receiver is performed when the SiPM receiver is not performing a measurement.

[0087] In the embodiments of this disclosure, if the background light intensity of the SiPM or LiDAR is high and there is a lot of noise, the threshold value of the channel corresponding to the next scanning surface is increased; if the background light is low, the threshold value of the channel corresponding to the next scanning surface is decreased. Simultaneously, the noise counts of the two SiPM units form a grayscale image, such as... Figure 6 Finally, multiple channels can form a column of grayscale image of the complete field of view. As the lidar rotates, grayscale data can be generated from a column to create an image, thereby generating a grayscale video synchronized with the rotation frequency.

[0088] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

[0089] Finally, it should be noted that the above descriptions are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A lidar, comprising: Multiple receiving devices, each of which can receive incident light and generate an electrical signal, and each receiving device has a corresponding threshold. and The control unit is coupled to the plurality of receiving devices and can obtain the intensity of the incident light according to the electrical signal, and adjust the threshold of the plurality of receiving devices individually according to the intensity of the incident light. The control unit is configured to form a grayscale image based on the intensity of incident light obtained by the plurality of receiving devices at multiple angles, wherein each pixel in the grayscale image corresponds to the intensity of incident light obtained by the receiving devices at at least one angle.

2. The lidar according to claim 1, wherein the receiving device comprises a silicon photomultiplier.

3. The lidar according to claim 1, wherein the incident light is the background light of the lidar, and the electrical signal is an electrical pulse.

4. The lidar according to claim 3, wherein the control unit is configured to: count pulses generated by the incident light that are above a threshold, obtain an incident light count value, and characterize the intensity of the incident light.

5. The lidar according to any one of claims 1-4, wherein, The control unit is configured to form the grayscale image based on the intensity of incident light obtained by the plurality of receiving devices at multiple angles when the receiving devices are not measuring the echo.

6. A control method for a lidar, wherein the lidar includes a plurality of receiving devices, the control method comprising: The receiver receives incident light and generates an electrical signal, and each receiver has a corresponding threshold. and The intensity of the incident light is obtained based on the electrical signal, and the threshold values ​​of the multiple receiving devices are individually adjusted based on the intensity of the incident light. A grayscale image is formed based on the intensity of incident light obtained by multiple receiving devices at multiple angles, wherein each pixel in the grayscale image corresponds to the intensity of incident light obtained by the receiving devices at at least one angle.

7. The control method according to claim 6, wherein the receiving device includes a silicon photomultiplier, the incident light is the background light of the lidar, and the electrical signal is an electrical pulse.

8. The control method according to claim 7, wherein the step of obtaining the intensity of the incident light based on the electrical signal comprises: The pulses generated by the incident light that exceed a threshold are counted to obtain the incident light count value, which characterizes the intensity of the incident light.

9. The control method according to any one of claims 6-8, wherein the step of receiving incident light through the receiving device is performed when the receiving device is not measuring the echo.

Images