Method and device for detecting smudginess of laser radar photomask

Abstract

The invention belongs to the technical field of laser radar detection, and particularly relates to a laser radar photomask smudginess detection method and device, and the method comprises the steps: S1, dividing a photomask detection region of a laser radar into a plurality of micro-regions; s2, emitting a first laser beam, and receiving a first echo signal; s3, according to the pulse width of the first echo signal, the smudginess condition of each micro-area is judged in sequence, and if smudginess possibly exists in the current micro-area, the step S4 continues to be executed; s4, emitting a second laser beam, and receiving a second echo signal; s5, according to the pulse width of the second echo signal, the smudginess condition of the current micro-area is judged, and if smudginess exists in the current micro-area, the smudginess type of the current micro-area is judged; and S6, processing the laser radar according to the smudginess type of each micro-area, and sending out an alarm prompt. The laser radar photomask smudginess detection method and device provided by the invention have the advantages of high detection precision and low misjudgment rate.

Description

Technical Field

[0001] The present invention belongs to the field of laser radar detection technology, and in particular relates to a laser radar mask contamination detection method and device. Background Art

[0002] As a three-dimensional optical measurement system, LiDAR (Light Detection and Ranging) is a radar system that detects the position, speed and other characteristic quantities of a target by emitting a laser beam. Its working principle is to emit a detection signal (laser beam) to the target, and then compare the received signal reflected from the target (target echo) with the transmitted signal. After appropriate processing, relevant information about the target can be obtained, such as target distance, direction, height, speed, attitude, and even shape parameters, so as to detect, track and identify the target. LiDAR has the advantages of high precision and high resolution, and also has the prospect of establishing a 3D model of the surrounding area. With the rapid development of autonomous driving technology, LiDAR is widely used in automobiles. The role of on-board LiDAR is to perceive the environment, assist the car in planning routes, assist driving safety, and detailed positioning.

[0003] Common laser radars include laser emitting devices, laser receiving devices, and light shields (also called light shields, light windows) and other components. The light shield is an indispensable part of the laser emission and receiving path. Its performance and functions mainly include the following aspects: 1. Protecting the laser transmitter and receiver: The window can prevent external elements such as dust, particulate matter and dirt from entering the laser radar system, thereby protecting the optical components of the laser transmitter and receiver from damage or contamination. 2. Transparency: The window must be transparent to ensure that the laser beam can pass through it, interact with the target object and return to the receiver for measurement. 3. Optical performance: The optical performance of the window must match the requirements of the laser system to ensure that the laser beam is not distorted or scattered when passing through the window. 4. Wear resistance and corrosion resistance: The window usually needs to have sufficient wear resistance and corrosion resistance to cope with the physical and chemical effects under different environmental conditions.

[0004] As a non-contact measuring device, the laser radar has a light mask set on the emission path of the laser emitting device. In actual applications, objects such as water mist and dust caused by weather conditions or vehicle exhaust gas adhere to the surface of the laser radar's light mask, and dust, scratches, sewage, mud stains, insect corpses and corrosion will form on the light mask, causing the laser radar's emitted signals and collected echo signals to attenuate, weakening the signal energy, resulting in the laser radar's ranging and reflectivity performance being reduced or even completely lost, and then unable to normally obtain environmental information around the vehicle, resulting in safety risks for the vehicle. Therefore, the cleanliness of the light mask directly affects the laser radar's range and measurement accuracy. To ensure the normal operation of the laser radar, it is necessary to promptly detect whether there is dirt on the laser radar's light mask, and promptly remind the user to remove the dirt if there is dirt.

[0005] In order to avoid undetected LiDAR blind spots caused by pollutants during autonomous driving, the LiDAR system should be able to detect obstructions on the glass window and trigger system safety measures (for example, system degradation and turning on the glass window cleaning and heating system to clean and dry the glass window) in a relatively short time to avoid safety risks. However, the existing LiDAR mask dirty detection method has low detection accuracy and is prone to missed reports. In order to improve the safety of vehicle driving, the current mask dirty detection method mainly reduces the triggering conditions of the dirty alarm, such as by setting a relatively low or wide alarm trigger threshold condition to improve the detection accuracy. Although this approach can improve the detection sensitivity and reduce the occurrence of missed reports to a certain extent, the false positive rate is also increased, resulting in the system frequently prompting that the LiDAR is dirty, affecting the user experience.

[0006] Therefore, providing a lidar mask contamination detection method and device with high detection accuracy is of great significance for promoting the application of lidar and the development of autonomous driving technology. Summary of the invention

[0007] The purpose of the present invention is to provide a laser radar mask contamination detection method with high detection accuracy in order to solve the above-mentioned technical problems.

[0008] In view of this, the present invention provides a method for detecting contamination of a laser radar mask, comprising: S1, dividing the laser radar mask detection area into several micro-areas; S2, emitting a first laser beam, and receiving a first echo signal generated by the first laser beam; S3, determining the contamination status of each micro-area in the laser radar mask in turn according to the pulse width of the first echo signal, and if the determination result is that the current micro-area may be contaminated, proceeding to step S4; if the determination result is that the current micro-area is not contaminated, marking the current micro-area as a clean area; S4, emitting a second laser beam, and receiving a second echo signal generated by the second laser beam; S5, determining the contamination condition of the current micro-area according to the pulse width of the second echo signal, and if it is determined that the current micro-area is contaminated, determining the contamination type of the current micro-area, and then continuing to execute step S6; if it is determined that the current micro-area is not contaminated, marking the current micro-area as a clean area; S6, processing the laser radar according to the dirt type of each micro-area and issuing an alarm prompt.

[0009] Furthermore, the step S3 includes: S31, sequentially comparing the pulse width W1 of the first echo signal returned by each point in the laser radar with a preset threshold value W 阈1 For comparison, if W1≤W 阈1 , then the current point is determined to be a clean point; if W1>W 阈1 , then the current point is determined to be a dirty point; S32, calculate the ratio K of the number of dirty spots in each micro-area to the total number of spots 1n , and the ratio of dirty points to the total number of points K 1n With the preset threshold K 阈1 For comparison, if K 1n ≤K 阈1 , then it is determined that there is no dirt in the current micro-area, and the current micro-area is marked as a clean area; if K 1n >K 阈1 , it is determined that the current micro-area may be dirty.

[0010] Furthermore, in the steps S2 and S4, the intensity of the second laser beam is greater than the intensity of the first laser beam.

[0011] Furthermore, the step S5 comprises: S51, obtaining a preset pulse width threshold curve L1 of a second echo signal and a pulse width maximum value curve L2 of a second echo signal; S52, processing the pulse width threshold curve L1 and the pulse width maximum value curve L2 to obtain a pulse width reference curve L0; S53, determining the contamination status of the current micro-area according to the pulse width W2 of the second echo signal returned from each point in the current micro-area: If it is determined that the current micro-area is contaminated, the contamination type of the current micro-area is determined, and then step S6 is continued; If it is determined that the current micro-area is not dirty, the current micro-area is marked as a clean area.

[0012] Further, the step S52 includes: S521, obtaining the pulse width threshold W corresponding to the second echo signal under different total use time of the laser radar according to the pulse width threshold curve L1 and the pulse width maximum value curve L2. 阈2 The maximum pulse width W 阈3 ; S522, sequentially comparing the pulse width threshold W corresponding to the second echo signal under different total laser radar usage times 阈2 The maximum pulse width W 阈3 The relative size of W 阈2 and W 阈3 The smaller value is used as the pulse width reference value W corresponding to the total use time of the laser radar in the pulse width reference curve L0. 基准 ; S523, the pulse width reference value W at each total usage time obtained in step S522 基准 Fitting is performed to obtain the pulse width reference curve L0.

[0013] Further, the step S53 includes: S531, obtain the current cumulative usage time t of the laser radar 累计 , and obtain the current accumulated usage time t on the pulse width reference curve L0 累计 The corresponding W 基准 The value of the pulse width maximum value curve L2 is obtained at the same time, and the current cumulative usage time t 累计 The corresponding maximum pulse width W 阈3 ; S532, sequentially compare the pulse widths W2 and W of the second echo signal returned from each point. 基准 The relative size of 基准 , then the current point is determined to be a clean point; if W3>W 基准 , then continue to execute step S533; S533, compare the pulse widths W2 and W of the second echo signal returned from the current point. 阈3 Relative size: If W2≤W 阈3 , it is determined that the contamination status of the current point is to be determined, and the step S534 is continued; If W3>W 阈3 , the current point is determined to be a dirty point, and step S535 is continued to determine the dirt type of the point; S534, compare the intensity W2 of the second echo signal returned from the current point with the intensity W1 of the first echo signal returned from the current point, and calculate the difference △W between W2 and W1. If △W<W 阈4 , then the current point is determined to be a clean point; if △W ≥ W 阈4, the current point is determined to be a dirty point, and step S535 is continued to determine the dirt type of the point; S535, obtaining a preset pulse width natural variation curve L3 of the second echo signal, and determining whether the dirt type of each point in the current micro-area is a type A dirt point or a type B dirt point according to the pulse width W2 of the second echo signal and the pulse width natural variation curve L3; S536, calculate the ratio K of the number of dirty points to the total number of points in the current micro-area 2n , and according to the ratio K of dirty points to the total number of points 2n With the preset threshold K 阈2 For comparison: If K 2n ≤K 阈2 , it is determined that there is no dirt in the current micro-area, and the current micro-area is marked as a clean area; If K 2n >K 阈2 , it is determined that the current micro-area is dirty, and step S537 is continued; Where n represents the number of the micro-area, and its values ​​are 1, 2, 3, ..., n. max , n max is the total number of micro-regions; S537, calculate the total number of type A dirt points P1 and the total number of type B dirt points P2 in the current dirt micro-area; then compare the value of P1 / (P1+P2) with the preset threshold value P 阈 Relative size: If P1 / (P1+P2)≥P 阈 , it is determined that the contamination of the current micro-area is caused by contaminants adhering to the mask; If P1 / (P1+P2)<P 阈 , it is determined that the contamination of the current micro-area is caused by the natural aging of the mask.

[0014] Furthermore, the step S535 includes: S5351, first obtain the current cumulative usage time t on the pulse width natural variation curve L3 累计 The corresponding pulse width naturally changes in value W 阈4 ; S5352, sequentially comparing the pulse widths W2 and W 阈4 Relative size of values: If the pulse width of the second echo signal W2 ≥ α*W 阈4 , then the current point is determined to be dirty due to contaminants adhering to the mask, and the current point is recorded as a type A dirty point; If W2<α*W 阈4, then the current point is determined to be dirty due to natural aging of the mask, and the current point is recorded as a type B dirty point.

[0015] Furthermore, the α is an adjustment coefficient, and the value of α is 0.8~1.0.

[0016] Further, the step S6 includes: If there are micro-areas of dirt in the LiDAR due to natural aging of the light mask, the intensity of the light emitted by the LiDAR is increased and a light mask aging warning is issued; If a dirty micro-area appears in the laser radar due to contaminants adhering to the mask, a dirty mask warning and flushing instruction will be issued to clean the mask.

[0017] A laser radar mask contamination detection device, wherein the laser radar mask contamination detection device adopts the above-mentioned laser radar mask contamination detection method to detect the mask contamination condition of the laser radar.

[0018] The beneficial effects of the present invention are: 1. In the present invention, through the steps S2 and S3, the overall dirtiness detection of the laser radar mask can be quickly performed. In this process, the setting standard of the clean area is relatively high, and the clean area in the mask can be quickly and accurately screened out. For areas where dirt may occur or the dirtiness is difficult to define, further screening and detection analysis can be performed to obtain them. In this way, resource allocation can be optimized, detection accuracy and efficiency can be improved, detection accuracy can be enhanced, false detections and missed detections can be reduced, and the amount of subsequent data processing can be reduced.

[0019] 2. The present invention first uses a first laser beam with lower intensity to perform preliminary and overall detection, and then uses a second laser beam with higher intensity to perform local and in-depth secondary screening of the suspected area, which can optimize energy consumption configuration and improve detection accuracy.

[0020] 3. The pulse width reference curve L0 and the pulse width natural variation curve L3 described in the present invention take into account the influence of multiple factors such as dirt, mask aging, and the maximum echo signal pulse width allowed for effective detection. The dirtiness of the mask can be judged by combining the pulse width reference curve L0 and the pulse width natural variation curve L3, which is more accurate and comprehensive.

[0021] 4. The laser radar mask contamination detection method described in the present invention classifies the types of mask contamination and takes appropriate measures to deal with different types of mask contamination. In this way, the detection results can reflect the cause of mask contamination and can also make the treatment measures taken more targeted. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the method for detecting contamination of a laser radar mask according to the present invention; Figure 2 It is a schematic diagram of the pulse width threshold curve L1 and the pulse width maximum value curve L2 in the present invention; Figure 3 It is a schematic diagram of a pulse width reference curve L0 obtained by processing the pulse width threshold curve L1 and the pulse width maximum value curve L2 in the present invention; Figure 4 is a schematic diagram of the pulse width natural variation curve L3 of the present invention; DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0024] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0026] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0027] like Figure 1 As shown, a method for detecting contamination of a laser radar mask comprises the following steps: S1, dividing the laser radar mask detection area into several micro-areas; S2, emitting a first laser beam, and receiving a first echo signal generated by the first laser beam; S3, determining the contamination status of each micro-area in the laser radar mask in turn according to the pulse width of the first echo signal, and if the determination result is that the current micro-area may be contaminated, proceeding to step S4; if the determination result is that the current micro-area is not contaminated, marking the current micro-area as a clean area; S4, emitting a second laser beam, and receiving a second echo signal generated by the second laser beam; S5, determining the contamination condition of the current micro-area according to the pulse width of the second echo signal, and if it is determined that the current micro-area is contaminated, determining the contamination type of the current micro-area, and then continuing to execute step S6; if it is determined that the current micro-area is not contaminated, marking the current micro-area as a clean area; S6, processing the laser radar according to the dirt type of each micro-area and issuing an alarm prompt.

[0028] Furthermore, during the execution of the laser radar mask dirt detection method, if it is determined that there is no dirt in the current micro-area, after marking the current micro-area as a clean area, the detection of the current micro-area is ended and the detection of the next micro-area is carried out.

[0029] During the use of the laser radar, the dirtiness of the laser radar mask, such as dust, rain, snow, insect corpses and other pollutants, will directly affect the light transmittance of the mask. These pollutants will scatter, absorb or block part of the emitted light, making it impossible for the emitted light to effectively penetrate the mask. When the emitted light is weakened or blocked, the system may take a longer time to accumulate sufficient signal strength, resulting in an increase in the pulse width of the echo signal. In addition, dirt may also cause reflection and scattering on the surface of the mask. These reflected and scattered light signals will be received by the receiving unit of the laser radar and superimposed on the normal echo signal, thereby increasing the complexity and pulse width of the echo signal. Therefore, the pulse width of the echo signal can reflect the dirtiness of the mask, so that the present invention can obtain the dirtiness of the mask by detecting the pulse width of the echo signal.

[0030] Specifically, in step S1, the micro-area may be in the shape of a sector, a rectangle, a triangle, etc. In the present invention, it is only necessary to divide the detection area of ​​the laser radar mask into a number of micro-areas with equal or approximately equal areas.

[0031] Preferably, in order to ensure detection accuracy and reduce data processing volume, in step S1, the area of ​​a single micro-region is ≤ 1 / 5 of the total area of ​​the detection region of the laser radar mask.

[0032] As some examples of the present invention, in the process of detecting dirt on the laser radar mask described in the present invention, an additional beam transceiver can be provided to transmit light for dirt detection, and the transmitted light can be received after passing through the mask; the laser beam transceiver and the laser radar chip of the laser radar itself can also be used to perform dirt detection without the need to provide an additional beam transceiver.

[0033] Furthermore, in step S3, the process of sequentially determining the contamination status of each micro-area in the laser radar mask according to the pulse width of the first echo signal is as follows: S31, sequentially comparing the pulse width W1 of the first echo signal returned by each point in the laser radar with a preset threshold value W 阈1 For comparison, if W1≤W 阈1 , then the current point is determined to be a clean point; if W1>W 阈1 , then the current point is determined to be a dirty point; S32, calculate the ratio K of the number of dirty spots in each micro-area to the total number of spots 1n , and the ratio of dirty points to the total number of points K 1n With the preset threshold K 阈1 For comparison, if K 1n ≤K 阈1 , then it is determined that there is no dirt in the current micro-area, and the current micro-area is marked as a clean area; if K 1n >K 阈1, it is determined that the current micro-area may be dirty, and step S4 needs to be continued; wherein n represents the number of the micro-area, and its value is 1, 2, 3, ..., n in sequence. max , n max is the total number of micro-regions.

[0034] As some examples of the present invention, the W 阈1 With K 阈1 The value of W can be set according to the detection accuracy requirements, experimental values ​​or empirical values. Generally, the W 阈1 The value of K can be set to 1.05~1.2 times the width of the echo signal received after the first laser beam passes through a new and clean mask; 阈1 The value of can be set to 5 to 10% or more. In the present invention, the K 阈1 The value can be set lower to meet the needs of detection accuracy.

[0035] In the present invention, through the steps S2 and S3, the overall dirtiness detection of the laser radar mask can be quickly performed. In this process, the setting standard of the clean area is relatively high, and the clean area in the mask can be quickly and accurately screened out. For areas where dirt may occur or the dirtiness is difficult to define, further screening and detection analysis can be performed to obtain them. In this way, resource allocation can be optimized, detection accuracy and efficiency can be improved, detection accuracy can be enhanced, false detections and missed detections can be reduced, and the amount of subsequent data processing can be reduced.

[0036] Furthermore, in the steps S2 and S4, the emitted first laser beam has a different frequency and / or intensity than the emitted second laser beam.

[0037] Preferably, the first laser beam and the second laser beam have the same frequency and different intensities; more preferably, the intensity of the second laser beam is greater than the intensity of the first laser beam.

[0038] Compared with the first laser beam, the increase in the intensity of the emitted light in the second laser beam causes the energy of the laser beam to increase accordingly. The high-energy laser beam can more easily penetrate obstacles during propagation, such as pollutants on the light mask, and maintain a high energy level in the atmosphere. During the laser emission and reception process, the high-intensity emitted light has less signal loss due to energy attenuation, and the echo signal is stronger and has a higher signal-to-noise ratio. In this way, the echo signal can more comprehensively reflect the increased complexity of the received echo signal and more comprehensively reflect the changes in the echo signal.

[0039] More importantly, if there is dirt on the surface of the mask, resulting in a large amount of reflected and scattered light on the surface of the mask, these additional light signals will be superimposed on the normal echo signal, thereby increasing the pulse width of the echo signal. In addition, if the dirt causes the surface of the mask to become rough or uneven, it may also make the direction of the reflected light more dispersed, further increasing the pulse width of the echo signal. On the contrary, if the mask is clean and the surface is in good condition, the increase in the intensity of the emitted light may cause the intensity of the received echo signal to remain unchanged or increase slightly. At this time, if the response time of the receiving system is fast enough and the noise level is low, the pulse width of the echo signal may remain unchanged or decrease slightly. Therefore, increasing the intensity of the emitted light is conducive to expanding the difference in the pulse width of the echo signal when the mask surface is dirty and clean, thereby improving the accuracy of dirt detection.

[0040] However, an increase in beam intensity usually means an increase in energy consumption. The present invention first uses a first laser beam with lower intensity for preliminary, overall detection, and then uses a second laser beam with higher intensity to perform local, in-depth secondary screening of the suspected area, which can optimize energy consumption configuration and improve detection accuracy.

[0041] Furthermore, in step S5, the process of determining the contamination condition of the current micro-area according to the pulse width of the second echo signal is as follows: S51, obtaining a preset pulse width threshold curve L1 of a second echo signal and a pulse width maximum value curve L2 of a second echo signal; S52, processing the pulse width threshold curve L1 and the pulse width maximum value curve L2 to obtain a pulse width reference curve L0; S53, determining the contamination status of the current micro-area according to the pulse width W2 of the second echo signal returned from each point in the current micro-area: If it is determined that the current micro-area is contaminated, the contamination type of the current micro-area is determined, and then step S6 is continued; If it is determined that the current micro-area is not dirty, the current micro-area is marked as a clean area.

[0042] Specifically, in step S51, the pulse width threshold curve L1 is a curve showing the change of the pulse width threshold of the second echo signal as the total use time of the laser radar increases. On the pulse width threshold curve L1, the pulse width threshold of the second echo signal corresponding to different total use times of the laser radar is the boundary value of whether there is dirt on the mask. When the pulse width of the second echo signal is higher than the corresponding pulse width threshold, it indicates that there is dirt at the point on the mask; when the pulse width of the second echo signal is lower than the corresponding pulse width threshold, it indicates that the point on the mask is clean.

[0043] Taking into account factors such as natural wear, aging and corrosion, in the present invention, Figure 2As shown, on the pulse width threshold curve L1, the pulse width threshold of the second echo signal gradually increases as the total use time of the laser radar increases. The pulse width threshold of the second echo signal corresponding to the total use time of each laser radar can be set through experiments or experience.

[0044] In the present invention, the pulse width maximum value curve L2 is a curve of the maximum value of the pulse width of the second echo signal allowed to ensure that the laser radar maintains a certain measurement accuracy as the total use time of the laser radar increases. When the pulse width of the second echo signal increases to a certain value, the pulse width of the echo signal makes it difficult to distinguish the signal from the noise, and the signal-to-noise ratio is reduced; at the same time, when the pulse width of the second echo signal increases to a certain value, in addition to the widening of the pulse width, it may also cause the shape of the echo signal to be distorted. This distortion may make it difficult for the signal to be accurately identified and processed, affecting the accuracy of the detection. Therefore, in the present invention, on the pulse width maximum value curve L2, as the total use time of the laser radar increases, the maximum value of the pulse width of the second echo signal allowed can be a certain value, or it can be a value. As the total use time of the laser radar increases, such as Figure 2 The gradually increasing values ​​are shown. In the pulse width maximum value curve L2, the maximum value of the pulse width of the second echo signal corresponding to different total use times of the laser radar can be determined by experiments or based on experience.

[0045] Usually, if Figure 2 As shown in the figure, in the early stage of laser radar use, that is, when the total use time of laser radar is short, the pulse width threshold corresponding to the same total use time of laser radar is smaller than the maximum value of pulse width; and as the use time of laser radar increases, the pulse width threshold corresponding to the same total use time of laser radar gradually increases, and because its increase rate is generally greater than the increase rate of the maximum value of pulse width, therefore, in the later stage of laser radar use, that is, when the total use time of laser radar is longer, the pulse width threshold corresponding to the same total use time of laser radar is greater than the maximum value of pulse width.

[0046] Furthermore, in step S52, the pulse width threshold curve L1 and the pulse width maximum curve L2 are processed to obtain the pulse width reference curve L0 as follows: S521, obtaining the pulse width threshold W corresponding to the second echo signal under different total use time of the laser radar according to the pulse width threshold curve L1 and the pulse width maximum value curve L2. 阈2 The maximum pulse width W 阈3 ; S522, sequentially comparing the pulse width threshold W corresponding to the second echo signal under different total laser radar usage times 阈2 The maximum pulse width W 阈3 The relative size of W 阈2 and W阈3 The smaller value is used as the pulse width reference value W corresponding to the total use time of the laser radar in the pulse width reference curve L0. 基准 ; S523, the pulse width reference value W at each total usage time obtained in step S522 基准 Fitting is performed to obtain Figure 3 The pulse width reference curve L0 is shown.

[0047] The pulse width reference curve L0 of the present invention takes into account the influence of multiple factors such as dirt, mask aging, and the maximum echo signal pulse width allowed for effective detection. The dirtiness of the mask can be judged more accurately and comprehensively in combination with the pulse width reference curve L0.

[0048] Furthermore, in step S53, the manner of determining the contamination condition of the current micro-region according to the pulse width W2 of the second echo signal returned by each point in the current micro-region is as follows: S531, obtain the current cumulative usage time t of the laser radar 累计 , and obtain the current accumulated usage time t on the pulse width reference curve L0 累计 The corresponding W 基准 The value of the pulse width maximum value curve L2 is obtained at the same time, and the current cumulative usage time t 累计 The corresponding maximum pulse width W 阈3 ; S532, sequentially compare the pulse widths W2 and W of the second echo signal returned from each point. 基准 The relative size of 基准 , then the current point is determined to be a clean point; if W3>W 基准 , then continue to execute step S533; S533, compare the pulse widths W2 and W of the second echo signal returned from the current point. 阈3 Relative size: If W2≤W 阈3 , it is determined that the contamination status of the current point is to be determined, and the step S534 is continued; If W3>W 阈3 , the current point is determined to be a dirty point, and step S535 is continued to determine the dirt type of the point; S534, compare the intensity W2 of the second echo signal returned from the current point with the intensity W1 of the first echo signal returned from the current point, and calculate the difference △W between W2 and W1. If △W<W 阈4 , then the current point is determined to be a clean point; if △W ≥ W 阈4 , the current point is determined to be a dirty point, and step S535 is continued to determine the dirt type of the point; S535, obtaining a preset pulse width natural variation curve L3 of the second echo signal, and determining whether the dirt type of each point in the current micro-area is a type A dirt point or a type B dirt point according to the pulse width W2 of the second echo signal and the pulse width natural variation curve L3; S536, calculate the ratio K of the number of dirty points to the total number of points in the current micro-area 2n , and according to the ratio K of dirty points to the total number of points 2n With the preset threshold K 阈2 For comparison: If K 2n ≤K 阈2 , it is determined that there is no dirt in the current micro-area, and the current micro-area is marked as a clean area; If K 2n >K 阈2 , it is determined that the current micro-area is dirty, and step S537 is continued; Where n represents the number of the micro-area, and its values ​​are 1, 2, 3, ..., n. max , n max is the total number of micro-regions; S537, calculate the total number of type A dirt points P1 and the total number of type B dirt points P2 in the current dirt micro-area; then compare the value of P1 / (P1+P2) with the preset threshold value P 阈 Relative size: If P1 / (P1+P2)≥P 阈 , it is determined that the contamination of the current micro-area is caused by contaminants adhering to the mask; If P1 / (P1+P2)<P 阈 , it is determined that the contamination of the current micro-area is caused by the natural aging of the mask.

[0049] As some examples of the present invention, the preset threshold value P 阈 The size of can be set as needed, and its value can be a certain value or a variable related to the total usage time of the laser radar. 阈 The value is 0.3~0.7.

[0050] Specifically, in step S535, the pulse width natural variation curve L3 is the general value or maximum value change of the pulse width of the second echo signal caused by the change in the performance of the laser radar mask due to natural aging and corrosion when the laser radar mask is not polluted. In actual use, the mask will inevitably age and corrode to a certain extent due to moisture, corrosive gases, dust or sand friction in the air. The aging and corrosion of the mask may introduce additional optical path length, causing the optical signal to experience a longer time delay during transmission, which will widen the pulse width of the echo signal. This is unavoidable and naturally exists. At this point, even if the mask is deeply cleaned, the pulse width of the second echo signal will still change to a certain extent compared to a brand new mask. Therefore, if Figure 4 As shown, the pulse width natural variation curve L3 shows a natural trend that the general value or maximum value of the pulse width of the second echo signal increases with the extension of the total use time.

[0051] Thus, in the present invention, the type of dirt can be obtained by comparing the pulse width of the second echo signal with the pulse width natural variation curve L3.

[0052] Furthermore, in step S535, the process of determining the dirt type of each point in the current micro-area according to the pulse width W2 of the second echo signal and the pulse width natural variation curve L3 is as follows: S5351, first obtain the current cumulative usage time t on the pulse width natural variation curve L3 累计 The corresponding pulse width naturally changes in value W 阈4 ; S5352, sequentially comparing the pulse widths W2 and W 阈4 Relative size of values: If the pulse width of the second echo signal W2 ≥ α*W 阈4 , then the current point is determined to be dirty due to contaminants adhering to the mask, and the current point is recorded as a type A dirty point; If W2<α*W 阈4 , then the current point is determined to be dirty due to natural aging of the mask, and the current point is recorded as a type B dirty point; Wherein, the α is an adjustment coefficient, and the value of α is 0.8~1.0.

[0053] In the present invention, by detecting the type of dirt in each micro-area, dirt caused by natural aging of the mask or dirt caused by contaminants adhering to the mask can be identified, and different processing methods are adopted to make the dirt detection method more accurate and comprehensive, and less prone to misjudgment and missed judgment.

[0054] Furthermore, in step S6, the process of processing the laser radar according to the dirt type of each micro-area is as follows: If a dirty micro-area appears in the LiDAR due to the natural aging of the light mask, the intensity of the light emitted by the LiDAR will be increased, and a light mask aging warning will be issued to remind the user to replace the light mask in time; If a dirty micro-area appears in the laser radar due to contaminants adhering to the mask, a dirty mask warning and flushing instruction will be issued to clean the mask.

[0055] Furthermore, when a dirty micro-area appears in the laser radar due to natural aging of the mask, the increase in the intensity of the laser radar emitted light can be set according to the test settings or the degree of aging of the mask.

[0056] Furthermore, in the step S6, after the mask is cleaned, the laser radar mask contamination detection method described in the present invention needs to be executed again to confirm the cleanliness of the mask after cleaning.

[0057] In addition, the present invention also provides a laser radar mask dirtiness detection device, which uses the above-mentioned laser radar mask dirtiness detection method to detect the mask dirtiness of the laser radar.

[0058] As some examples of the present invention, the laser radar mask dirt detection device includes: A transmitting unit capable of transmitting a laser beam for dirt detection; a receiving unit capable of receiving an echo signal generated by the laser beam emitted by the emitting unit; A detection unit, which can detect the echo signal received by the receiving unit to obtain information such as the pulse width of the echo signal; The contamination judgment unit can detect the contamination of the mask according to information such as the pulse width of the echo signal detected by the detection unit.

[0059] In addition, the present invention also discloses a computer-readable storage medium, which stores a computer program that can be loaded by a processor and execute the above-mentioned laser radar mask dirt detection method.

[0060] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for detecting contamination of a laser radar mask, characterized in that: include: S1, dividing the laser radar mask detection area into several micro-areas; S2, emitting a first laser beam, and receiving a first echo signal generated by the first laser beam; S3, determining the contamination status of each micro-area in the laser radar mask in turn according to the pulse width of the first echo signal, and if the determination result is that the current micro-area may be contaminated, proceeding to step S4; if the determination result is that the current micro-area is not contaminated, marking the current micro-area as a clean area; S4, emitting a second laser beam, and receiving a second echo signal generated by the second laser beam; S5, determining the contamination condition of the current micro-area according to the pulse width of the second echo signal, and if it is determined that the current micro-area is contaminated, determining the contamination type of the current micro-area, and then continuing to execute step S6; if it is determined that the current micro-area is not contaminated, marking the current micro-area as a clean area; S6, processing the laser radar according to the dirt type of each micro-area and issuing an alarm prompt.

2. The laser radar mask contamination detection method according to claim 1, characterized in that: The step S3 comprises: S31, sequentially comparing the pulse width W1 of the first echo signal returned by each point in the laser radar with a preset threshold value W 阈1 For comparison, if W1≤W 阈1 , then the current point is determined to be a clean point; if W1>W 阈1 , then the current point is determined to be a dirty point; S32, calculate the ratio K of the number of dirty spots in each micro-area to the total number of spots 1n , and the ratio of dirty points to the total number of points K 1n With the preset threshold K 阈1 For comparison, if K 1n ≤K 阈1 , then it is determined that there is no dirt in the current micro-area, and the current micro-area is marked as a clean area; if K 1n >K 阈1 , it is determined that the current micro-area may be dirty.

3. The laser radar mask contamination detection method according to claim 1, characterized in that: In the steps S2 and S4, the intensity of the second laser beam is greater than the intensity of the first laser beam.

4. The laser radar mask contamination detection method according to claim 1, characterized in that: The step S5 comprises: S51, obtaining a preset pulse width threshold curve L1 of a second echo signal and a pulse width maximum value curve L2 of a second echo signal; S52, processing the pulse width threshold curve L1 and the pulse width maximum value curve L2 to obtain a pulse width reference curve L0; S53, determining the contamination status of the current micro-area according to the pulse width W2 of the second echo signal returned from each point in the current micro-area: If it is determined that the current micro-area is contaminated, the contamination type of the current micro-area is determined, and then step S6 is continued; If it is determined that the current micro-area is not dirty, the current micro-area is marked as a clean area.

5. The laser radar mask contamination detection method according to claim 4, characterized in that: The step S52 comprises: S521, obtaining the pulse width threshold W corresponding to the second echo signal under different total use time of the laser radar according to the pulse width threshold curve L1 and the pulse width maximum value curve L2. 阈2 The maximum pulse width W 阈3 ; S522, sequentially comparing the pulse width threshold W corresponding to the second echo signal under different total laser radar usage times 阈2 The maximum pulse width W 阈3 The relative size of W 阈2 and W 阈3 The smaller value is used as the pulse width reference value W corresponding to the total use time of the laser radar in the pulse width reference curve L0. 基准 ; S523, the pulse width reference value W at each total usage time obtained in step S522 基准 Fitting is performed to obtain the pulse width reference curve L0.

6. The laser radar mask contamination detection method according to claim 5, characterized in that: The step S53 comprises: S531, obtain the current cumulative usage time t of the laser radar 累计 , and obtain the current accumulated usage time t on the pulse width reference curve L0 累计 The corresponding W 基准 The value of the pulse width maximum value curve L2 is obtained at the same time, and the current cumulative usage time t 累计 The corresponding maximum pulse width W 阈3 ; S532, sequentially compare the pulse widths W2 and W of the second echo signal returned from each point. 基准 The relative size of 基准 , then the current point is determined to be a clean point; if W3>W 基准 , then continue to execute step S533; S533, compare the pulse widths W2 and W of the second echo signal returned from the current point. 阈3 Relative size: If W2≤W 阈3 , it is determined that the contamination status of the current point is to be determined, and the step S534 is continued; If W3>W 阈3 , the current point is determined to be a dirty point, and step S535 is continued to determine the dirt type of the point; S534, compare the intensity W2 of the second echo signal returned from the current point with the intensity W1 of the first echo signal returned from the current point, and calculate the difference △W between W2 and W1. If △W<W 阈4 , then the current point is determined to be a clean point; if △W ≥ W 阈4 , the current point is determined to be a dirty point, and step S535 is continued to determine the dirt type of the point; S535, obtaining a preset pulse width natural variation curve L3 of the second echo signal, and determining whether the dirt type of each point in the current micro-area is a type A dirt point or a type B dirt point according to the pulse width W2 of the second echo signal and the pulse width natural variation curve L3; S536, calculate the ratio K of the number of dirty points to the total number of points in the current micro-area 2n , and according to the ratio K of dirty points to the total number of points 2n With the preset threshold K 阈2 For comparison: If K 2n ≤K 阈2 , it is determined that there is no dirt in the current micro-area, and the current micro-area is marked as a clean area; If K 2n >K 阈2 , it is determined that the current micro-area is dirty, and step S537 is continued; Where n represents the number of the micro-area, and its values ​​are 1, 2, 3, ..., n. max , n max is the total number of micro-regions; S537, calculate the total number of type A dirt points P1 and the total number of type B dirt points P2 in the current dirt micro-area; then compare the value of P1 / (P1+P2) with the preset threshold value P 阈 Relative size: If P1 / (P1+P2)≥P 阈 , it is determined that the contamination of the current micro-area is caused by contaminants adhering to the mask; If P1 / (P1+P2)<P 阈 , it is determined that the contamination of the current micro-area is caused by the natural aging of the mask.

7. The laser radar mask contamination detection method according to claim 6, characterized in that: The step S535 includes: S5351, first obtain the current cumulative usage time t on the pulse width natural variation curve L3 累计 The corresponding pulse width naturally changes in value W 阈4 ; S5352, sequentially comparing the pulse widths W2 and W 阈4 Relative size of values: If the pulse width of the second echo signal W2 ≥ α*W 阈4 , then the current point is determined to be dirty due to contaminants adhering to the mask, and the current point is recorded as a type A dirty point; If W2<α*W 阈4 , then the current point is determined to be dirty due to natural aging of the mask, and the current point is recorded as a type B dirty point.

8. The method for detecting contamination of a laser radar mask according to claim 7, characterized in that: The α is an adjustment coefficient, and the value of α is 0.8~1.

0.

9. The method for detecting contamination of a laser radar mask according to claim 6, characterized in that: The step S6 comprises: If there are micro-areas of dirt in the LiDAR due to natural aging of the light mask, the intensity of the light emitted by the LiDAR is increased and a light mask aging warning is issued; If a dirty micro-area appears in the laser radar due to contaminants adhering to the mask, a dirty mask warning and flushing instruction will be issued to clean the mask.

10. A laser radar mask dirt detection device, characterized in that: The laser radar mask dirtiness detection device uses the laser radar mask dirtiness detection method described in any one of claims 1 to 9 to detect the mask dirtiness of the laser radar.

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