TWI876338B - Lidar system and crosstalk reduction method thereof - Google Patents

Abstract

A LiDAR system includes a microcontroller, a laser light source, a lens module and a receiver. The lens module includes a laser beam splitter module and a receiver lens module, the laser beam splitter module receiving a laser light and diffracting the laser light into multiple diffractive lights emitted toward a target. The receiver lens module receives a reflective light signal of the diffractive lights reflected from the target and emits the reflective light signal towards the receiver. A frame of the LiDAR system includes a plurality of subframes. The microcontroller compares the average distance values at the same sampling area of each subframes within the frame, eliminates the subframes with abnormal average distance values, and merges the other subframes with similar average distance values as the final distance value of the frame.

Description

LiDAR system and method for eliminating external light interference

The present invention relates to a lidar system, and in particular to a lidar system with the function of eliminating external light interference.

In recent years, LiDAR (Light Detection and Ranging) technology has been widely used in the autonomous/semi-autonomous driving and safety warning of automobiles. The main components of LiDAR include: sensors (such as direct time of flight (D-ToF) sensors), laser light sources, scanners and data processors. Current lidar scanning methods can have many forms, such as using an optical phased array (OPA) or a diffractive optical element (DOE) to project a small area of light, using a micro-electromechanical system (MEMS) micro-vibration mirror or a polygon mirror to perform a serpentine back-and-forth scan or oblique scan of a large area, or using a DOE or a multi-point linear arrangement of light sources or multiple reflections to expand the beam and project a linear beam, and use mechanical rotation to horizontally scan a large area. Through the above scanning methods, the sensor can receive the reflected light signal.

However, the laser light source sensing performed by the above scanning method has a small aspect ratio (screen ratio), so it is necessary to continuously receive the reflected light signal at a higher frequency. If the sensor receives other light sources (such as interfering light sources (crosstalk) or background light sources (ambient light)), it is easy to cause the data processor to misjudge the distance, affecting driving safety. Therefore, there is an urgent need for a lidar system that can effectively filter and exclude interfering light sources and background light sources in the received light signal to correctly judge the distance and maintain driving safety. In addition, there is also an urgent need for a method for eliminating external light interference, so that the lidar system can effectively filter and exclude interfering light sources and background light sources in the received light signal to correctly judge the distance and maintain driving safety.

The main purpose of the present invention is to provide a lidar system that can effectively filter and eliminate interfering light sources and background light sources in the received light signal to accurately judge the distance and maintain driving safety.

In order to achieve the above-mentioned purpose, the present invention provides a lidar system, including: a microcontroller; a laser light source coupled to the microcontroller; a lens module, and a receiver coupled to the microcontroller, wherein: the lens module includes a laser spectroscope module and a receiver lens module, the laser spectroscope module receives the laser light emitted from the laser light source, and diverts the laser light into multiple diffusive lights, which are emitted toward a target. The receiver lens module receives the reflected light signal reflected after the diffusive light contacts the target, and emits the reflected light signal to the receiver. The laser light source emits a pulse signal with a cycle time. The microcontroller controls the receiver to open within a sensor shutter time and close within a reset time in each cycle time. A frame of the lidar system includes a plurality of subframes, and each subframe is imaged in each cycle time. Each subframe includes an environmental image of a plurality of sampling blocks, each sampling block includes a plurality of pixels, and each reflected light signal can obtain a distance value at each pixel according to a flight time. The microcontroller takes an average distance value of the distance values of the plurality of pixels to represent the average distance value of the sampling block. The microcontroller compares the average distance value of each subframe in the frame on the same sampling block, eliminates the subframes with abnormal average distance values, and merges the remaining subframes with similar average distance values as a final distance value of the frame.

In order to achieve the above-mentioned purpose, the present invention provides a method for eliminating external light interference, which is applicable to the above-mentioned lidar system, and the method includes: sampling a plurality of sampling blocks in an environmental image, each sampling block includes a plurality of pixels, the total number of pixels included in the sampling blocks is not more than 10% of the number of pixels in the environmental image, and the number of the sampling blocks is at least five; for the same sampling block, within each sensor shutter time of a plurality of subframes of a frame, a reflected light signal is obtained, and according to the flight time of the reflected light signal, the distance value represented by each pixel in the sampling block is calculated; and the average value of all pixel distance values in the sampling block is calculated to represent the average distance value of the sampling block. Among the sub-frames of the plurality of sampling blocks at the same position, the sub-frames with significantly different average distance values are eliminated; and the distance values of the environment images of the sub-frames that are not eliminated are merged to form the final distance value of the frame.

The effect of the present invention is that by projecting a large area light spot through a diffraction optical element, a large area image can be obtained after one or several pulse scans without the need for back and forth scanning, thereby greatly improving the frame rate and effectively eliminating the impact caused by external light interference.

100: LiDAR system

101:Microcontroller

102: Laser light source

104: Laser light

106: Lens module

108: Receiver lens module

110: Laser spectrometer module

112: Receiver

120: Target

122: Image field

124: Field of view

126: Reflected light

202: Concave lens

204: Convex lens

206:Diffraction optical element

208: Concave mirror

210: Collimator lens set

302: Laser light

304:Diffraction optical element

306a,306b,306c: Point cloud

502: Collimator assembly

5021: Concave lens

5022: Convex lens

504:Diffraction optical element

506: Laser light

508:Diffuse light

512: Collimator lens set

5121: Concave lens

5122: Convex lens

514:Diffraction optical element

516:Laser light

518:Diffuse light

520: Concave mirror

PW: Pulse Width

T: cycle time

SS: sensor shutter time

R: Reset time

Ts: start time

Tl: End time

801,802,803,804: Situation

900:Method

902,904,906,908,910,912,914,916: Steps

1000:Method

1002,1004,1006,1008,1010: Steps

A,B,C,D,E: Sampling blocks

FIG. 1 is a schematic diagram of a lidar system of the present invention; FIG. 2 is a schematic diagram of the internal structure of some components shown in FIG. 1; FIG. 3 shows the operation of a diffraction optical component; FIG. 4 shows the operation of the present invention at different distances; FIG. 5A is a collimator lens group configuration according to the present invention; FIG. 5B is another collimator lens group configuration according to the present invention; FIG. 6 is an example timing diagram according to the present invention; FIG. 7 is another example timing diagram according to the present invention; and FIG. 8 is a timing diagram of the present invention under different conditions. FIG. 9 is a flow chart of an external light interference elimination method of the present invention; FIG. 10A is another example timing chart of the present invention; FIG. 10B is a flow chart of another external light interference elimination method of the present invention; FIG. 11A is a real environment image; FIG. 11B, FIG. 11C and FIG. 11D are sampling examples of FIG. 11A; and FIG. 12A, FIG. 12B, FIG. 12C, FIG. 12D, FIG. 12E and FIG. 12F are sampling situations of different subframes in the same frame.

The following is a more detailed description of the implementation of the present invention with the help of diagrams and component symbols, so that those who are familiar with the technology can implement it accordingly after reading this manual.

The present invention provides a lidar system with a function of eliminating external light interference, and a method for eliminating external light interference of the lidar system. By projecting a large area light spot through a diffractive optical element (DOE), a large area image can be obtained after one or several pulse scans without the need for back and forth scanning, thereby greatly improving the frame rate and effectively eliminating the impact caused by external light interference.

Referring to FIG. 1 , the present invention provides a lidar system 100, including a microcontroller (MCU) 101, a laser light source (TX) 102, a lens module 106, and a receiver (RX) 112. The lens module 106 includes a receiver lens module 108 and a laser spectrometer module 110. The laser light source 102 and the receiver 112 are coupled to the microcontroller 101.

In order to measure the distance between the target 120 and the lidar system 100, first, the microcontroller 101 controls the laser light source 102 to emit laser light 104. Then, the laser spectrometer module 110 scatters the laser light 104 into a plurality of light spots, which are distributed in the field of image (FOI) 122, and the field of image 122 completely covers the target 120. Subsequently, after the light spots contact the target 120, they are reflected into a plurality of reflected lights 126, which are distributed in the field of view (FOV) 124. The receiver lens module 108 receives the reflected light 126 and transmits the reflected light signal to the receiver 112. The receiver 112 transmits the received signal to the microcontroller 101 for subsequent image analysis.

Please refer to FIG. 2. The receiver lens module 108 in FIG. 1 includes a lens module composed of at least one concave lens 202 and at least one convex lens 204. The concave lens 202 and the convex lens 204 form a focusing lens group, which can focus the reflected light 126 in FIG. 1 so as to transmit the optical signal to the receiver 112. The laser spectrometer module 110 in FIG. 1 includes a diffractive optical element (DOE) 206, a concave mirror 208 and a collimation lens group (collimation lens) 210. The operation of the laser spectrometer module 110 will be described in detail below.

Please refer to FIG. 3 . When the laser light 302 is directed to the diffraction optical element 304 , the diffraction optical element 304 will diffract the laser light 302 into thousands to tens of thousands of light spots. The light spots form point clouds 306a, 306b, and 306c at different distances. Point cloud 306a is closest to the diffraction optical element 304 , has the most dense light spots, and has the smallest point cloud coverage area; while point cloud 306c is farthest from the diffraction optical element 304 , has the least dense light spots, and has the largest point cloud coverage area. The diffraction optical element 304 may be, for example, HCPDOE ^™ of Tyrafos, but the present invention is not limited thereto.

Since the point cloud coverage area shown in FIG3 is proportional to the square of the distance, when the distance is far, the point cloud coverage area will expand rapidly, causing the light energy per unit area to decrease, thereby resulting in insufficient reflected light intensity. A significant increase in the intensity of the laser light 302 may result in a decrease in the life of the equipment and may easily cause damage to the human eye. Therefore, please refer to FIG4 , the focal length adjustable lens module composed of at least one concave lens 202 and at least one convex lens 204 can adjust the field of view size according to the detection range, so that the light energy per unit area at different distances (e.g., 15 meters, 40 meters, 100 meters, 200 meters and 300 meters) is roughly equal, to prevent the situation where the reflected light intensity is insufficient when the distance is far. Alternatively, multiple lens modules with fixed focal lengths may be used, each lens module including at least one concave lens 202 and at least one convex lens 204, and the lens modules may be switched according to the ranging range to adjust the field of view.

One way to achieve the configuration shown in FIG. 4 is to use a collimator set to converge the coverage area of the diffraction light within a certain range. By adjusting the focal length, the collimator set can adjust the divergence angle of the outgoing light and adjust the image field range of the projected light spot according to the ranging range to achieve the effect shown in FIG. 4. A plurality of collimators with fixed focal lengths can be used, and the collimators can be switched according to the ranging range to adjust the image field range. Alternatively, a collimator set with a variable focal length can be used, and the collimators can be switched according to the ranging range to adjust the image field range. Referring to FIG. 5A , a collimator set configuration is to place the collimator set 502 directly in front of the diffraction optical element 504, wherein the mirror surface of the collimator set 502 is perpendicular to the incident direction of the laser light 506. As shown in FIG. 5A , the collimator lens set 502 can converge the diffracted light 508 emitted by the diffraction optical element 504 to be substantially parallel to each other, so that the unit area light energy of the diffracted light 508 at different distances is substantially maintained equal. In one embodiment, the collimator lens set 502 includes a concave lens 5021 and a convex lens 5022, wherein the distance between the concave lens 5021 and the convex lens 5022 can be adjusted to control the divergence angle.

Referring to FIG. 5B , another collimator lens set configuration is to place the collimator lens set 512 in front of the concave mirror 520, so that the concave mirror 520 collects the diffracted light emitted by the diffracting optical element 514. As shown in FIG. 5B , the diffracting optical element 514 diffracts the laser light 516 into multiple diffracted light beams 518, which are reflected and converged by the concave mirror 520 for the first time and incident on the collimator lens set 512. Subsequently, the collimator lens set 512 converges the diffracted light beams 518 for the second time to be substantially parallel to each other, so that the unit area light energy of the diffracted light beams 518 at different distances is substantially maintained equal. In one embodiment, the collimator lens assembly 512 includes a concave lens 5121 and a convex lens 5122, wherein the distance between the concave lens 5121 and the convex lens 5122 can be adjusted to control the divergence angle. Compared with the configuration shown in FIG. 5A, this configuration can collect diffracted light at a larger angle, thereby increasing the projected light energy per unit area without increasing the laser light intensity.

In the use scenario of vehicle automatic driving, when the vehicle is driving, the interference signals that the lidar system 100 may receive include scanning lasers from vehicles in the opposite lane ahead, front directional pulse lasers from vehicles in the opposite lane ahead, scanning lasers from vehicles in the same lane ahead, and rear directional pulse lasers from vehicles in the same lane ahead. Therefore, such interference signals must be eliminated in an appropriate manner to accurately measure distance and maintain driving safety.

When the laser light source 102 of FIG. 1 emits a pulse signal, in order to eliminate interference signals, the microcontroller 101 can activate or deactivate the receiver 112 according to the ranging range, so that the receiver 112 only receives the reflected light signal within the ranging range. For example, if the object to be measured is 300 meters away, the time required from the laser light source 102 emitting a pulse signal to the receiver 112 receiving the reflected light signal is 2μs (R=ct/2, where R is the distance, c is the speed of light 3×10 ⁸ m/s, and t is time (seconds)). Therefore, the receiver 112 can be activated synchronously with the laser light source 102 within a cycle time, the sensing time is 2μs, and the rest of the time is turned off to prevent receiving interference signals. Referring to FIG. 6 , the laser source (TX) emits a pulse signal with a pulse width PW at a cycle time T. The receiver (RX) opens at a sensor shutter time SS within the cycle time T and closes at a reset time R, where T=SS+R. The sensor shutter time SS and the reset time R are determined according to the range. In one embodiment, when the range is 300 meters, the sensor shutter time SS is 2μs, the reset time R is 2μs, the cycle time T is 4μs, and the pulse width PW is 100ns. At this time, the receiver (RX) can receive reflected light signals within a range of 0 to 300 meters, and the theoretical frame rate (number of scans) can be as high as 1/T=2.5×10 ⁵ f/s.

Please refer to FIG7. In addition to the upper limit of the ranging range, the lower limit of the ranging range can also be set for the receiver (RX) by adjusting the sensor shutter time SS. In FIG7, the start time Ts of the sensor shutter time SS is determined according to the lower limit of the ranging range, and the end time Tl is determined according to the upper limit of the ranging range. In one embodiment, when the ranging range is 90 to 300 meters, the start time Ts is 600ns, the end time Tl is 2μs, the sensor shutter time SS is 1400ns, the reset time R is 2μs, the cycle time T is 4μs, and the pulse width PW is 100ns. At this time, the receiver (RX) can receive the reflected light signal within 90 to 300 meters, and the theoretical frame rate is 1/T=2.5×10 ⁵ f/s.

In order to remove the interference signal received during the activation of the receiver (RX), in the environment image including a plurality of sampling blocks, the microcontroller 101 can compare the signal receiving conditions between adjacent subframes of the same sampling block to remove abnormal values. Please refer to FIG8 . In one embodiment, each frame includes three subframes. Each subframe is imaged at each cycle time T and includes a plurality of sampling blocks. The first subframe is obtained by the microcontroller calculating the first reflected light signal received by the receiver (RX) during the first sensor shutter time. The second subframe is obtained by the microcontroller calculating the second reflected light signal received by the receiver (RX) during the second sensor shutter time. The third subframe is obtained by the microcontroller calculating the third reflected light signal received by the receiver (RX) during the third sensor shutter time. Each sampling block includes a plurality of pixels, and a distance value can be obtained for each reflected light signal at each pixel according to a time of flight (ToF). The microcontroller takes an average distance value of the distance values of the plurality of pixels to represent the average distance value of the sampling block. In the environment image including the plurality of sampling blocks, the microcontroller compares the average distance value of each subframe in the frame on the plurality of sampling blocks at the same position. In scenario 801, on the plurality of sampling blocks at the same position, the average distance values of the receiver (RX) in three subframes are similar, indicating that the three reflected light signals come from similar distances. Therefore, scenario 801 can be regarded as a normal scenario, and the microcontroller 101 fuses the distance values represented by the reflected light signals in the three subframes to calculate the final distance value of the frame. Among them, "fusion" can be performed by taking an average value, superposition, selection or other methods. In scenario 802, the average distance values of the reflected light signals of the first subframe and the second subframe are different in a plurality of sampling blocks at the same position, indicating that at least one of the first subframe and the second subframe receives an interference signal. At this time, the third subframe is compared with the second subframe. If the average distance value of the third subframe is close to that of the second subframe, it can be determined that the second subframe and the third subframe are normal, while the first subframe is abnormal. As shown in FIG8 , in scenario 802, the second subframe and the third subframe are normal, while the first subframe is abnormal. At this time, scenario 802 can still be regarded as a normal scenario, but only the reflected light signals of the second subframe and the third subframe are used to calculate the final distance value, and the reflected light signal of the first subframe is eliminated. In scenario 803, the average distance values of the reflected light signals of the first subframe and the second subframe are different, and the average distance values of the reflected light signals of the second subframe and the third subframe are also different. At this time, although the average distance values of the reflected light signals of the first subframe and the third subframe are similar, due to the lack of two consecutive similar signals of subframes, it is impossible to confirm which is a normal signal and which is an abnormal signal. Therefore, scenario 803 is regarded as an abnormal scenario, and the frame is discarded. In scenario 804, the average distance values of the reflected light signals of the three subframes are all different. At this time, because it is impossible to confirm which is a normal signal and which is an abnormal signal, scenario 804 is regarded as an abnormal scenario, and the frame is discarded. This method uses fewer subframes and has a lower resolution (because only two subframes are used for fusion), but has a faster matching speed. It is suitable for fast dynamic detection scenarios, such as foreground or background detection of a moving car.

Please refer to Figure 9. In one embodiment, method 900 is used to implement the determination process of different scenarios shown in Figure 8. In step 902, the receiver obtains the reflected light signal of the first subframe. In step 904, the receiver obtains the reflected light signal of the second subframe. In step 906, the microcontroller compares whether the average distance values of the reflected light signals of the first subframe and the second subframe on a plurality of sampling blocks at the same position are similar. If so, in step 908, the microcontroller merges the distance values represented by the reflected light signals of the first subframe and the second subframe into the final distance value of the frame, and the process ends. Among them, "fusion" can be performed by taking an average value, superposition, selection or other methods. If not, in step 910, the receiver obtains the reflected light signal of the third subframe. In step 912, the microcontroller compares whether the average distance values of the reflected light signals of the second subframe and the third subframe on multiple sampling blocks at the same position are similar. If so, in step 914, the microcontroller merges the distance values represented by the reflected light signals of the second subframe and the third subframe into the final distance value of the frame, and the process ends. If not, in step 916, the signal of the frame is discarded and the process ends.

Please refer to FIG. 10A. In one embodiment, a plurality of subframes (preferably at least six) may be used in one frame to more accurately distinguish normal signals from abnormal signals. In the example shown in FIG. 10, in an environmental image including a plurality of sampling blocks, on the same sampling block, the reflected light signal of the fifth subframe falls at a different position within the sensor shutter time SS than the remaining subframes (i.e., the flight time is different), so the average distance value of the fifth subframe will be different from the remaining subframes. At this time, the microcontroller eliminates the fifth subframe and then merges the average distance values of the remaining subframes to form the final distance value of the frame. Due to the movement of the object, in each sampling block, the signal reflected by each subframe entering the sensor does not necessarily appear in the same pixel. Therefore, in this embodiment, "fusion" may include superimposing all signals appearing in different pixels in the subframes that have not been eliminated in the same sampling block, and then taking the average value of each superimposed pixel. For example, in one embodiment, the following Table 1A to Table 1F respectively represent the first to sixth subframes in the same frame of the same sampling block, where each small square represents a pixel, and the one with a value represents the sub-distance value measured by the pixel of the subframe, while the one without a value represents no sub-distance value. For each subframe, the average distance value of the pixels with sub-distance values is taken, and the abnormal subframes are eliminated according to the average distance value of each subframe. From Table 1A to Table 1F, it can be seen that the average distance value of the sixth subframe is obviously different from that of the other subframes, so the sixth subframe is regarded as an abnormal value and eliminated. Then, as shown in Table 1G, each pixel of the normal subframe (the first to the fifth subframe, that is, Table 1A to Table 1E) is superimposed, and then the average value of each pixel with sub-distance value after superposition is taken as the final distance value of this sampling block in this frame. During superposition, if the same pixel has multiple sub-range values, the average or the maximum value is selected. If the pixel does not have a sub-range value, the minimum value in the ranging range (such as 0) is selected. Alternatively, if the same pixel has multiple sub-range values, the average or the minimum value is selected. If the pixel does not have a sub-range value, the maximum value in the ranging range (such as 500 or 1000) is selected. This method uses more sub-frames and has a higher resolution (due to the use of multiple sub-frame fusion), which is suitable for non-fast dynamic detection scenarios.

Please refer to FIG. 10B , method 1000 is used to implement the determination process of the scenario shown in FIG. 10A . In step 1002, the microcontroller samples a plurality of sampling blocks in the environmental image, each sampling block including a plurality of pixels. The total number of pixels included in the sampling blocks is no more than 10% of the number of pixels in the environmental image, and the number of sampling blocks is at least five. In step 1004, for the same sampling block, a reflected light signal is obtained within each sensor shutter time of a plurality of subframes of a frame, and the distance value represented by each pixel in the sampling block is calculated based on the flight time of the reflected light signal. In step 1006, the average value is calculated with all pixel distance values in the sampling block, which represents the average distance value of the sampling block. In step 1008, the microcontroller eliminates subframes with significantly different average distance values (or abnormal subframes) in the subframes of the plurality of sampling blocks at the same position. In step 1010, the microcontroller merges the pixel distance values of the environment image of the subframes that have not been eliminated (or normal subframes) to become the final distance value of the frame.

Figure 11A is a real environment image. In order to improve the computing efficiency, it is not necessary to measure the distance of every pixel on the entire image, but several blocks can be sampled for distance measurement. Each sampling block includes a plurality of pixels, such as 10×10 pixels. The sampled pixels should not be too many, for example, not more than 10% of the total number of pixels, to improve the computing efficiency. Figure 11B shows an example of sampling two blocks. Figure 11C shows an example of sampling five blocks. Figure 11D shows an example of sampling nine blocks. The number of sampling blocks should not be less than five to better grasp the environmental information. In a normal subframe, if the sampling blocks with normal distance values exceed a certain ratio (e.g. 80% or 88.9%, where 80% means that when five blocks are sampled, one sampling block is allowed to have an abnormal distance value, and 88.9% means that when nine blocks are sampled, one sampling block is allowed to have an abnormal distance value), otherwise it is regarded as an abnormal subframe. The microcontroller fuses the distance values of the pixels of the environment image of the multiple subframes to become the final distance value of the frame.

Please refer to FIG. 12A to FIG. 12F. In an embodiment in which a frame includes six subframes, the six subframes are FIG. 12A, FIG. 12B, FIG. 12C, FIG. 12D, FIG. 12E and FIG. 12F, respectively. Among them, the second subframe (FIG. 12B) and the sixth subframe (FIG. 12F) have external light intrusion. In order to effectively filter out the interfered subframes, the distance values measured by each pixel in each sampling block in each subframe can be fused as the sub-distance value of the sampling block in the subframe, and then the six sub-distance values of the same sampling block in the six subframes are compared with each other to filter out abnormal values. In one embodiment, the method of filtering out abnormal values is to calculate the average value (μ), standard deviation (σ), upper threshold value and lower threshold value of the six sub-distance values in the same sampling block within six sub-frames, wherein the upper threshold value is the average value plus a number of standard deviations (μ+nσ), and the lower threshold value is the average value minus a number of standard deviations (μ-nσ), wherein the size of n is determined according to experimental data and actual needs, and can be an integer or a non-integer, such as (but not limited to) 1 or 1.5. In the embodiments shown in Tables 2, 3 and 4 below, n=1 is used as an example for explanation, but the present invention is not limited thereto. Then, the subframes with sub-distance values greater than the upper threshold or less than the lower threshold are eliminated, and the remaining subframes with similar sub-distance values are merged as the final distance value of the frame.

Tables 2, 3, and 4 show possible sensing results. In the example shown in Table 2, in the first subframe, there is no obstacle in front of sampling block A. At this time, the distance of sampling block A is considered to be the farthest distance (e.g., 500 meters). In the second subframe, there is external light intrusion into sampling block A, and in the sixth subframe, there is external light intrusion into sampling blocks A, B, C, D, and E. At this time, as shown in Table 2, the distance values of the second and sixth subframes of sampling block A are lower than the lower threshold value, so they should be considered as abnormal values and filtered out. The distance values of the sixth subframes of sampling blocks B, C, D, and E are all lower than the individual lower threshold values, so they should be considered as abnormal values and filtered out.

In the example shown in Table 3, in the fourth subframe, there is external light intrusion in sampling block A, and the measured distance is very close to the normal value, while in the sixth subframe, there is external light intrusion in sampling blocks A, B, C, D, and E. At this time, as shown in Table 3, the distance value of the fourth subframe of sampling block A is higher than the upper threshold value, and the distance value of the sixth subframe is lower than the lower threshold value, so it should be considered as an abnormal value and filtered out. The distance values of the sixth subframes of sampling blocks B, C, D, and E are all lower than the individual lower threshold values, so they should be considered as abnormal values and filtered out. Therefore, even though the distances measured by sampling block A in the fourth and sixth subframes are very close to normal values, the two subframes can still be correctly identified as abnormal values and filtered out.

In the example shown in Table 4, in the sixth subframe, external light intrudes into sampling blocks B, C, D, and E. At this time, as shown in Table 4, the distance values of the sixth subframe of sampling blocks B, C, D, and E are all lower than the individual lower threshold values, so they should be considered as abnormal values and filtered out.

The above is only used to explain the preferred embodiment of the present invention, and is not intended to limit the present invention in any form. Therefore, any modification or change of the present invention made under the same spirit of the invention should still be included in the scope of protection intended by the present invention.

100: LiDAR system

101:Microcontroller

102: Laser light source

104: Laser light

106: Lens module

108: Receiver lens module

110: Laser spectrometer module

112: Receiver

120: Target

122: Image field

124: Field of view

126: Reflected light

Claims (12)

A lidar system includes: a microcontroller; a laser light source coupled to the microcontroller; a lens module, and a receiver coupled to the microcontroller, wherein: the lens module includes a laser spectroscope module and a receiver lens module, the laser spectroscope module receives laser light emitted from the laser light source, and diverts the laser light into multiple diffusive lights, and the diffusive lights are emitted toward a target; the receiver lens module receives a reflected light signal reflected after the diffusive lights contact the target, and sends the reflected light signal to the receiver; the laser light source emits a pulse signal in a cycle time; the microcontroller controls the receiver to sense a pulse signal in each cycle time. The invention discloses a lidar system for detecting a light emitting diode (LED) system for detecting a light emitting diode (LED) system. The lidar system is provided with a plurality of subframes, each of which is imaged at each cycle time. Each subframe includes an environment image of a plurality of sampling blocks, each of which includes a plurality of pixels, and each reflected light signal can obtain a distance value at each pixel according to a flight time. The microcontroller obtains an average distance value of the distance values of the plurality of pixels, which represents the average distance value of the sampling block. The microcontroller compares the average distance value of each subframe in the frame on the same sampling block, eliminates the subframe with abnormal average distance value, and merges the remaining subframes with similar average distance value as a final distance value of the frame. The lidar system as described in claim 1, wherein the receiver lens module includes a focal length adjustable lens module composed of at least one concave lens and at least one convex lens, and the field of view size is adjusted according to a distance measurement range. The lidar system as described in claim 1, wherein the receiver lens module includes a plurality of lens modules with fixed focal lengths, each lens module includes at least one concave lens and at least one convex lens, and the lens modules are switched according to a ranging range to adjust the field of view. The lidar system as described in claim 1, wherein the laser spectrometer module includes a diffraction optical element and a plurality of collimating lens sets with fixed focal lengths, and the collimating lens sets are switched according to a distance measurement range to adjust the image field range. The lidar system as described in claim 1, wherein the laser spectrometer module includes a diffraction optical element and a collimator lens set with a variable focal length, and the collimator lens set is switched according to a ranging range to adjust the image field range. As described in claim 4 or 5, the diffraction optical element diffracts the laser light into the diffraction lights, the collimator set is arranged directly in front of the diffraction optical element, and the mirror surface of the collimator set is perpendicular to the incident direction of the laser light, so as to converge the diffraction lights to be substantially parallel to each other. The lidar system as described in claim 4 or 5 further includes a concave mirror, the diffraction optical element diffracts the laser light into the diffracted light, the concave mirror collects the diffracted light, and the collimating lens set is arranged in front of the concave mirror to converge the diffracted light to be substantially parallel to each other. A lidar system as described in claim 1, wherein the sensor shutter time and the reset time are determined according to the ranging range. The lidar system as described in claim 8 further includes a start time and an end time, and the microcontroller controls the receiver to turn on between the start time and the end time in each cycle time, and turn off the rest of the time; the start time is determined according to the lower limit of the ranging range, and the end time is determined according to the upper limit of the ranging range. A lidar system includes: a microcontroller; a laser light source coupled to the microcontroller; a lens module, and a receiver coupled to the microcontroller, wherein: the lens module includes a laser spectroscope module and a receiver lens module, the laser spectroscope module receives laser light emitted from the laser light source, and diverts the laser light into multiple diffusive lights, and the diffusive lights are emitted toward a target; the receiver lens module receives a reflected light signal reflected after the diffusive lights contact the target, and sends the reflected light signal to the receiver; the laser light source emits a pulse signal at a cycle time; the microcontroller controls the receiver to emit a pulse signal at each cycle time; The frame includes a first subframe, a second subframe and a third subframe, and the first subframe, the second subframe and the third subframe respectively include a plurality of sampling blocks; the first subframe is a first reflected light signal received by the receiver in a first sensor shutter time and calculated by the microcontroller; the second subframe is a second reflected light signal received by the receiver in a second sensor shutter time and calculated by the microcontroller; the third subframe is a third reflected light signal received by the receiver in a third sensor shutter time and calculated by the microcontroller; in the frame including In an environmental image of a plurality of sampling blocks, the microcontroller compares the average distance value of each subframe in the frame on a plurality of sampling blocks at the same position, and compares whether the average distance value of the first reflected light signal and the average distance value of the second reflected light signal are similar; if the average distance values of the first reflected light signal and the second reflected light signal on the plurality of sampling blocks at the same position are similar, the microcontroller merges a first distance value represented by the first reflected light signal and a second distance value represented by the second reflected light signal as the final distance value of the frame; if the average distance values of the first reflected light signal and the second reflected light signal on the plurality of sampling blocks at the same position are similar, the microcontroller merges a first distance value represented by the first reflected light signal and a second distance value represented by the second reflected light signal as the final distance value of the frame; If the average distance values of the sampling blocks at the same position are different, and the average distance values of the second reflected light signal and the third reflected light signal at the same position of the sampling blocks are similar, the microcontroller will fuse the second distance value represented by the second reflected light signal and the third distance value represented by the third reflected light signal as the final distance value of the frame; or if the average distance values of the first reflected light signal and the second reflected light signal at the same position of the sampling blocks are different, and the average distance values of the second reflected light signal and the third reflected light signal at the same position of the sampling blocks are different, the frame will be discarded. A method for eliminating external light interference in a lidar system as described in claim 1, the method comprising: sampling a plurality of sampling blocks in an environmental image, each sampling block including a plurality of pixels; the total number of pixels included in the sampling blocks is no more than 10% of the number of pixels in the environmental image, and the number of the sampling blocks is at least five; for the same sampling block, within each sensor shutter time of a plurality of subframes of a frame, obtaining A reflected light signal is obtained, and according to the flight time of the reflected light signal, the distance value represented by each pixel in the sampling block is calculated; the average value is calculated using the distance values of all pixels in the sampling block to represent the average distance value of the sampling block; among the subframes of the plurality of sampling blocks at the same position, the subframes with abnormal average distance values are eliminated; and the distance values of the environment images of the subframes that are not eliminated are integrated to obtain the final distance value of the frame. The method for eliminating external light interference as described in claim 11 further includes: for one of the sampling blocks, in each subframe of the frame, fusing the distance value measured by each pixel in the sampling block as a sub-distance value of the sampling block in the subframe; calculating an average distance value, a standard deviation, and a distance value of the sub-distance values of the subframes; An upper threshold and a lower threshold, wherein the upper threshold is the average distance value plus a number of the standard deviations, and the lower threshold is the average distance value minus a number of the standard deviations; and subframes whose sub-distance values are greater than the upper threshold or less than the lower threshold are eliminated, and the remaining subframes whose sub-distance values are similar are merged as the final distance value of the frame.