Optical window pollution detection method for laser radar and laser radar

Abstract

The present invention discloses an optical window pollution detection method for laser radar and laser radar. The method realizes the optical window pollution detection of laser radar based on the laser radar main system and the auxiliary window detection system, including: the laser radar main system obtains the number of echo pulses, the echo pulse width and the echo front threshold time, and determines the scanning azimuth corresponding to the echo; the auxiliary window detection system includes multiple optical sub-circuits, each of which corresponds to a fixed optical window area at a specific angle and its echo amplitude ratio; through the number of echo pulses, the echo pulse width, the echo front threshold time, the echo corresponding scanning azimuth, and the optical sub-circuit corresponding window position and echo amplitude ratio, jointly determine whether the laser radar optical window pollutants exist, the pollution area, the pollution type, the pollution degree and the pollution change trend. The present invention can realize the comprehensive monitoring of laser radar optical window pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of laser radar, and in particular to an optical window contamination detection method for laser radar and a laser radar. Background Art

[0002] LiDAR is a laser transmitting and receiving system that measures the distance and emissivity of the target by detecting the changes in the time parameters of the transmitted and received laser or the optical parameters of the laser itself (phase, wavelength, etc.). As a carrier, laser can be interfered by many factors during the space transmission process. It not only carries the distance and reflectivity information of the target, but also carries the information of pollutants / obstructions on the optical window, the disturbance of air flow in space, floating objects, rain, snow, fog, haze, smoke, dust, flying insects and other non-measured targets, and is also mixed with background light noise information. The existence of the above non-measured target information creates obstacles to the extraction of measured target information.

[0003] For the above interference information, different responses can be made based on the different locations of the interference source. For the information on pollutants / obstructions on the optical window, a window detection system can be set up inside the radar, and the decoupling of the window pollution / obstruction information and the measured target information can be achieved through auxiliary optical paths and circuit structures. Existing technical solutions include: first, a fixed optical window detection device is set up, and a laser different from the radar ranging laser wavelength penetrates a specific position of the optical window and is received by a dedicated detection device. The pollution / obstruction information is obtained by calculating the attenuation level of the laser. This solution does not change the detection position as the laser radar scanning position changes; second, a mobile optical window detection device is set up, which moves with the scanning mechanism of the radar, and can realize the pollution / obstruction information detection of a specific strip area of ​​the optical window within the full scanning angle range of the radar. The above two solutions may cause false detection due to various measurement errors and interferences, or cause missed detection due to the discontinuity of the coverage area, or increase the complexity of the radar system due to complex optical-mechanical structures and auxiliary power supply requirements, and both have limitations. Summary of the invention

[0004] The purpose of the present invention is to provide an optical window contamination detection method and a laser radar for laser radar, so as to realize comprehensive detection of optical window contamination of the laser radar and improve the accuracy and reliability of detection.

[0005] To achieve the above object, according to a first aspect of the present invention, a method for detecting optical window contamination of a laser radar is provided. The method realizes optical window contamination detection of the laser radar based on a laser radar main system and an auxiliary window detection system, comprising:

[0006] The laser radar main system transmits a first laser pulse and receives a corresponding first echo pulse, obtains the number of echo pulses, the echo pulse width and the echo front threshold time through the first echo pulse, and determines the scanning azimuth corresponding to the echo; each scanning azimuth corresponds to an optical window area of ​​a specific angle;

[0007] The auxiliary window detection system includes a plurality of optical sub-circuits and an auxiliary system data processing unit, each of which corresponds to a fixed optical window area at a specific angle; each of which emits a second laser pulse and receives a corresponding second echo pulse; wherein the laser wavelengths of the first laser pulse and the second laser pulse are different; the auxiliary system data processing unit is configured to obtain a corresponding echo amplitude ratio according to the electrical characteristics of the second echo pulse; wherein the echo amplitude ratio is a ratio of an echo amplitude under an actual working state to an echo amplitude under an ideal pollution-free state;

[0008] The number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and the corresponding window position and echo amplitude ratio of the optical sub-circuit are used to jointly determine the presence or absence of pollutants in the optical window of the lidar, the area where the pollution is located, the type of pollution, the degree of pollution and the trend of pollution change.

[0009] In the above scheme, the main laser radar system includes:

[0010] A first transmitting unit configured to transmit a first laser pulse;

[0011] a first receiving unit, configured to receive a first echo pulse corresponding to the first laser pulse, and convert the optical signal into an electrical signal;

[0012] The main system data processing unit is configured to obtain the number of echo pulses, the echo pulse width and the echo front threshold time by setting a threshold comparator according to the electrical characteristics of the first echo pulse;

[0013] A scanning unit is configured to drive and control the radar motor plus the rotating mirror structure to rotate the radar at a set speed to achieve radar scanning;

[0014] The main control unit is used to control the radar's laser pulse emission, echo pulse reception, echo pulse data processing, and the timing and logical relationship between the three.

[0015] In the above scheme, each optical sub-circuit includes:

[0016] a second emitting unit configured to emit a second laser pulse;

[0017] The second receiving unit is configured to receive a second echo pulse corresponding to the second laser pulse and convert the optical signal into an electrical signal.

[0018] In the above scheme, the optical sub-circuit and the laser radar main system work in different areas and time periods: when the laser radar main system scans to angle A, the optical sub-circuit located in the range of A+180°±B starts to work, and the time when the optical sub-circuit emits laser pulses is separated from the time when the laser radar main system emits laser pulses; where B is a preset angle value.

[0019] In the above scheme, the presence or absence of optical window contamination of the laser radar is determined by the number of echo pulses, echo pulse width, echo front threshold time and echo amplitude ratio, including:

[0020] For a certain window area to be detected, if the number of echo pulses is greater than the preset number threshold, the laser radar main system determines that there is pollution; at this time, if the echo pulse width is greater than the preset pulse width threshold or the echo front threshold time is earlier than the preset time threshold, the laser radar main system further determines that there must be pollution;

[0021] If the number of echo pulses is equal to the preset number threshold, and the echo front threshold time is earlier than the preset time threshold, the laser radar main system determines that there is contamination;

[0022] If the echo amplitude ratio is lower than the preset threshold, the auxiliary window detection system determines that there is contamination;

[0023] If it is determined that there is contamination, the first determination value is output; if it is determined that there must be contamination, the second determination value is output, and the first determination value is no longer output at this time; wherein the first determination value is smaller than the second determination value;

[0024] Setting a first weight and a second weight for the laser radar main system and the auxiliary window detection system respectively; wherein the first weight is greater than the second weight;

[0025] Calculate the weighted sum of the judgment values ​​output by the laser radar main system and the auxiliary window detection system. If the weighted sum is greater than a preset weighted sum threshold, it is determined that the window area to be detected is contaminated;

[0026] Or a certain measurement time period is set, and the average value of the weighted sums calculated multiple times within the calculation period is calculated. If the average value of the weighted sum is greater than a preset weighted sum threshold, it is determined that the window area to be detected is contaminated.

[0027] In the above scheme, the area where the optical window of the laser radar is contaminated is determined by the scanning azimuth corresponding to the echo and the window position corresponding to the optical sub-circuit, including:

[0028] Determine the corresponding window area according to the scanning azimuth angle corresponding to the echo, and combine it with the corresponding window position of the optical sub-circuit, and take the intersection of the two as the window area to be detected;

[0029] The union of multiple window areas to be detected that are judged to be contaminated is taken to obtain the area where the optical window of the laser radar is contaminated.

[0030] In the above scheme, the optical window pollution type of the laser radar is determined by the echo pulse width, the echo front threshold time and the echo amplitude ratio, including:

[0031] Pollution types include uniform pollution and point pollution;

[0032] If the echo pulse widths and echo front threshold moments corresponding to different scanning angles of the laser radar main system are similar, and the echo amplitude ratios of multiple optical sub-circuits of the auxiliary window detection system are similar, it is determined to be uniformly contaminated;

[0033] If the echo pulse width of the lidar main system at a specific angle is greater than that in other directions, and the echo front threshold time is earlier than that in other directions, and the echo amplitude ratio of the auxiliary window detection system at the same angle is lower than that in other directions, it is judged as point pollution.

[0034] In the above scheme, the degree of contamination of the optical window of the laser radar is determined by the echo pulse width and the echo amplitude ratio, including:

[0035] For a certain window area to be detected, a first pollution degree is determined by the echo pulse width, and a second pollution degree is determined by the echo amplitude ratio;

[0036] Setting a third weight for the first pollution degree and setting a fourth weight for the second pollution degree; wherein the third weight is greater than the fourth weight;

[0037] The pollution degree of the window area to be detected is jointly determined by calculating the weighted sum of the first pollution degree and the second pollution degree.

[0038] In the above scheme, the optical window pollution change trend of the laser radar is determined by the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and the optical sub-circuit corresponding window position and echo amplitude ratio, including:

[0039] Through the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and optical sub-circuit corresponding window position and echo amplitude ratio in multiple measurement time periods, the presence or absence of optical window pollutants, the pollution area, pollution type and pollution degree of the lidar in multiple measurement time periods are determined, and finally the change trend of optical window pollution of the lidar is determined.

[0040] According to a second aspect of the present invention, a laser radar is provided, which adopts the optical window contamination detection method for laser radar described in any one of the above technical solutions to realize optical window contamination detection of the laser radar.

[0041] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0042] The present invention combines the main laser radar system with the auxiliary window detection system, and respectively collects a variety of information such as the number of echo pulses, the echo pulse width, the echo front threshold time, the echo corresponding scanning azimuth, and the optical sub-circuit corresponding window position and the echo amplitude ratio for the real-time scanning window position and the fixed window position, so as to comprehensively judge the presence of pollutants in the laser radar optical window, the pollution area, the pollution type, the pollution degree and the pollution change trend, so as to realize comprehensive and real-time monitoring of the laser radar optical window pollution, provide a practical and effective solution for the realization of the laser radar functional safety indicators, and also provide data support for the monitoring of the radar long-range ranging capability and near-end ranging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A flow chart of an optical window contamination detection method for a laser radar provided in an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of a window area to be detected provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] In order to solve the optical window detection problem of laser radar, the present invention provides an optical window pollution detection method for laser radar, such as Figure 1 As shown, an optical window detection system is used to realize optical window pollution detection of a laser radar. The window detection system includes: a laser radar main system and an auxiliary window detection system.

[0047] The main laser radar system includes:

[0048] A first transmitting unit configured to transmit laser pulses;

[0049] A first receiving unit, configured to receive an echo light pulse corresponding to the laser pulse, convert the light signal into an electrical signal and perform appropriate signal conditioning;

[0050] The main system data processing unit is configured to extract the number of echo pulses, the leading and trailing edge threshold times and the threshold pulse width by setting a threshold comparator according to the electrical characteristics of the echo pulses.

[0051] The scanning unit is configured to drive and control the radar motor plus the rotating mirror structure to rotate at a set speed to achieve radar scanning.

[0052] The main control unit controls the radar's laser pulse emission, echo pulse reception and voltage adjustment, echo pulse data processing, and the timing and logical relationship between the three.

[0053] Based on the laser radar main system, the threshold moments and threshold pulse width information of the leading and trailing edges of the echo pulse are obtained. Due to the control of the scanning unit, the window area corresponding to the obtained threshold moment and threshold pulse width information changes in real time. Each threshold moment and threshold pulse width data obtained corresponds to an optical window area at a specific angle.

[0054] In the main system of the laser radar, the comparator threshold type can be set to a fixed threshold, corresponding to the acquisition of threshold time and threshold pulse width information. Due to the presence of window pollution or obstructions, the echo caused by the window is detected before the echo of the measured target (in the normal state without pollution or obstructions, this echo is usually suppressed to a negligible level during the radar design and production process). For the laser radar system, it is equivalent to adding a layer of echo judgment and solution. When this pollution / obstruction becomes serious, this echo will increase accordingly. After reaching a certain level, it will trigger the threshold comparator and may also overlap with the echo of the near-end measured target, thereby seriously interfering with the extraction of distance and reflectivity information in the echo information of the near-end measured target. Based on the threshold comparator, the threshold time information and threshold pulse width information of the echo pulse are obtained, which can be compared with the time window set manually inside the radar. By reasonably setting the time window, the threshold moment of the window pollution echo is excluded from the time window. At the same time, the comparison with the time window can also give a judgment and evaluation of whether there is pollution / obstruction and the type and degree of pollution obstruction.

[0055] The auxiliary window detection system includes multiple optical sub-circuits and an auxiliary system data processing unit. Each optical sub-circuit corresponds to a fixed optical window area at a specific angle, and each optical sub-circuit includes:

[0056] a second emitting unit configured to emit a second laser pulse;

[0057] The second receiving unit is configured to receive a second echo pulse corresponding to the second laser pulse and convert the optical signal into an electrical signal.

[0058] Each optical sub-circuit emits a second laser pulse and receives a corresponding second echo pulse; wherein the laser wavelengths of the first laser pulse and the second laser pulse are different.

[0059] The auxiliary system data processing unit is configured to obtain the corresponding echo amplitude ratio according to the electrical characteristics of the second echo pulse; wherein the echo amplitude ratio is the ratio of the echo amplitude under the actual working state to the echo amplitude under the ideal pollution-free state. Each optical sub-circuit corresponds to a fixed optical window area at a specific angle, and the echo amplitude ratio obtained by the optical sub-circuit represents the transmittance level of the optical window attachment in this area to the measuring laser beam, which indirectly reflects the pollution and covering level of the window in this area.

[0060] When performing optical window contamination detection on LiDAR,

[0061] The first transmitting unit transmits a laser pulse;

[0062] A first receiving unit receives an echo pulse generated by the laser pulse;

[0063] According to the time characteristics of the echo pulse, the optical window area corresponding to the scanning angle, the number of echo pulses, the threshold time of the leading and trailing edges of a single echo pulse or multiple echo pulses, and the threshold pulse width information are obtained.

[0064] The second transmitting unit transmits laser pulses;

[0065] A second receiving unit receives the echo pulse generated by the laser pulse;

[0066] According to the amplitude characteristics of the echo pulse, the ratio of the echo amplitude under the actual working state of the corresponding optical window detection area to the calibrated amplitude is obtained.

[0067] In order to improve the detection accuracy, the main laser radar system and the auxiliary radar detection system work in different bands and regions. The laser wavelength of the first transmitting unit is different from that of the second transmitting unit and has a large wavelength difference (which is convenient for adding filters in the detector to eliminate mutual interference); when the radar scans to angle A, the optical sub-circuit within the range of A+180°±B starts to work, and the light source pulse emission time of this sub-circuit is separated from the laser pulse emission time of the first transmitting unit; where B is a preset angle value, preferably 10°. The same applies to the pitch angle.

[0068] The presence or absence of optical window pollutants, the area of ​​pollution, the type of pollution, the degree of pollution and the pollution change trend of the laser radar are determined by the number of echo pulses, the width of echo pulses, the threshold time of the echo front, the scanning azimuth corresponding to the echo, and the window position and echo amplitude ratio corresponding to the optical sub-circuit, as shown in Table 1.

[0069] Table 1 Comprehensive analysis table

[0070]

[0071] For example, based on the number of echo pulses, the echo front threshold time, the echo pulse width and the echo amplitude ratio, it is jointly determined whether there is contamination or shielding in the area corresponding to the laser radar optical window.

[0072] Taking a single pulse as an example, for the window area corresponding to a certain scanning angle of the laser radar main system, if the number of echo pulses is greater than the preset number threshold 1, it is determined that there is pollution. At this time, if the pulse width is greater than the preset pulse width threshold or the echo front threshold is earlier than the preset time threshold, it can also be determined that there is pollution, and the accuracy of the determination is improved. In order to highlight the difference in the determination results, it is determined here that there must be pollution. If the number of window echo pulses corresponding to a certain scanning angle is equal to the preset threshold 1, and the echo front threshold is earlier than the preset time threshold, it is determined that there is pollution.

[0073] If there are multiple pulses, the corresponding preset number threshold is set in combination with the time window and the number of pulses.

[0074] For the same window area in the auxiliary window detection system, if the echo amplitude ratio is lower than the preset threshold value, the auxiliary window detection system determines that there is contamination.

[0075] When it is determined that there is contamination, the laser radar main system and the auxiliary window detection system output the first judgment value; if it is determined that there is contamination, the laser radar main system outputs the second judgment value first, and no longer outputs the first judgment value at this time; wherein the first judgment value is less than the second judgment value. If there is no contamination, it outputs zero.

[0076] The result of the main system is the main one between the main system and the auxiliary system, so different weights can be assigned to the two. The first weight and the second weight are set for the main laser radar system and the auxiliary window detection system respectively; wherein the first weight is greater than the second weight. Then the weighted sum of the judgment values ​​output by the main laser radar system and the auxiliary window detection system is calculated, and a weighted sum threshold is set. If the average value of the weighted sum is greater than the preset weighted sum threshold, it is determined that the window area is contaminated.

[0077] In view of the fact that errors may exist in a single measurement, resulting in inconsistent judgment results of various parameters, a certain measurement time period is set, and judgment is made based on multiple measurement results within the period. For example, a certain measurement time period is set, and the average value of the weighted sum calculated multiple times within the period is calculated. If the average value of the weighted sum is greater than the preset weighted sum threshold, it is determined that the window area is contaminated.

[0078] When making a pollution judgment, the area where the laser radar optical window pollution is located should be determined by the scanning azimuth corresponding to the echo and the window position corresponding to the optical sub-circuit. Specifically, the corresponding window area is determined according to the scanning azimuth corresponding to the echo, and the intersection of the two is the window area to be detected, such as Figure 2 As shown. For multiple contaminated window areas to be detected, the union of them can be taken to obtain the area where the laser radar optical window is contaminated. Then, according to the size of the area where the laser radar optical window is contaminated, the total contamination and local contamination are determined.

[0079] The pollution on the optical window can be divided into window material damage such as scratches and corrosion, modification or window adhesion of dust, sand, oil stains, water mist, flying insects and other situations. Due to the different pollution mechanisms, the pollution results can be divided into two categories: uniform pollution and point pollution. Uniform pollution can be evaluated by the detection value of any optical sub-circuit in the auxiliary window detection system. Point pollution needs to be evaluated by comprehensive judgment of the measurement values ​​given by the main system and the auxiliary system. For uniform pollution of the optical window, the echo amplitude ratio of N optical sub-circuits is the same or close, and the echo front threshold time and echo pulse width corresponding to different scanning angles of the radar are the same or close; for point pollution of the optical window, the echo amplitude ratio of N optical sub-circuits is quite different, and the echo front threshold time and echo pulse width corresponding to different scanning angles of the radar are quite different. In a specific angle direction, the echo amplitude ratio of the optical sub-circuit is much smaller than that in other directions, the echo front threshold time is much earlier than that in other directions, and the echo pulse width is much larger than that in other directions. The main optical system and the auxiliary optical system determine that the angle direction of the polluted window is consistent. In extreme cases, when the polluted area is in the area not covered by N optical sub-circuits, the echo amplitude ratios of the N optical sub-circuits are the same or close, and the echo front threshold time and echo pulse width corresponding to different radar scanning angles are quite different. Based on the above logic, the type of pollution (uniform or point-like) can be determined.

[0080] For the pollution degree value, the pollution degree of the optical window of the laser radar can be determined by the echo pulse width and the echo amplitude ratio. For example, for a certain window area to be detected, the first pollution degree is determined by the echo pulse width, and the second pollution degree is determined by the echo amplitude ratio; in order to give priority to the results of the main system, a third weight is set for the first pollution degree, and a fourth weight is set for the second pollution degree; wherein the third weight is greater than the fourth weight; the pollution degree of the window area to be detected is determined by calculating the weighted sum of the first pollution degree and the second pollution degree. wherein the first pollution degree and the second pollution degree can be set to 0 to 100%, 0 corresponds to the ideal pollution-free state, and 100% corresponds to the value that affects the radar performance.

[0081] Finally, by collecting data from multiple measurement cycles and combining all the above judgments, the pollution trend of the laser radar's optical window over time can be determined.

[0082] In addition, the present invention also provides a laser radar, which adopts the optical window contamination detection method for laser radar described in any one of the above technical solutions to realize optical window contamination detection of the laser radar.

[0083] In summary, the present invention combines the laser radar main system with the auxiliary radar detection system, collects various information such as the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and optical sub-circuit corresponding window position and echo amplitude ratio for the real-time scanning window position and fixed window position, and comprehensively judges the presence or absence of pollution, the pollution area, pollution type, pollution degree and pollution change trend, so as to realize comprehensive and real-time monitoring of laser radar optical window pollution, provide a practical and effective solution for the realization of laser radar functional safety indicators, and also provide data support for the monitoring of radar long-range ranging capability and near-end ranging accuracy.

[0084] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0085] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0086] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting optical window contamination for laser radar, characterized in that: The method realizes the optical window pollution detection of the laser radar based on the laser radar main system and the auxiliary window detection system, including: The laser radar main system emits a first laser pulse and receives a corresponding first echo pulse, obtains the number of echo pulses, the echo pulse width and the echo front threshold time through the first echo pulse, and determines the scanning azimuth corresponding to the echo; each scanning azimuth corresponds to an optical window area of ​​a specific angle; The auxiliary window detection system includes a plurality of optical sub-circuits and an auxiliary system data processing unit, each of which corresponds to a fixed optical window area at a specific angle; each of which emits a second laser pulse and receives a corresponding second echo pulse; wherein the laser wavelengths of the first laser pulse and the second laser pulse are different; the auxiliary system data processing unit is configured to obtain a corresponding echo amplitude ratio according to the electrical characteristics of the second echo pulse; wherein the echo amplitude ratio is a ratio of an echo amplitude under an actual working state to an echo amplitude under an ideal pollution-free state; The presence of pollutants in the optical window of the laser radar, the area where the pollution is located, the type of pollution, the degree of pollution and the trend of pollution change are determined through the number of echo pulses, the width of echo pulses, the threshold time of the echo front edge, the scanning azimuth corresponding to the echo, and the window position and echo amplitude ratio corresponding to the optical sub-circuit. Among them, the presence or absence of optical window contamination of the laser radar is determined by the number of echo pulses, echo pulse width, echo front threshold time and echo amplitude ratio, including: For a certain window area to be detected, if the number of echo pulses is greater than the preset number threshold, the laser radar main system determines that there is pollution; at this time, if the echo pulse width is greater than the preset pulse width threshold or the echo front threshold time is earlier than the preset time threshold, the laser radar main system further determines that there must be pollution; If the number of echo pulses is equal to the preset number threshold, and the echo front threshold time is earlier than the preset time threshold, the laser radar main system determines that there is contamination; If the echo amplitude ratio is lower than the preset threshold, the auxiliary window detection system determines that there is contamination; If it is determined that there is contamination, the first determination value is output; if it is determined that there must be contamination, the second determination value is output, and the first determination value is no longer output at this time; wherein the first determination value is smaller than the second determination value; Setting a first weight and a second weight for the laser radar main system and the auxiliary window detection system respectively; wherein the first weight is greater than the second weight; Calculate the weighted sum of the judgment values ​​output by the laser radar main system and the auxiliary window detection system. If the weighted sum is greater than a preset weighted sum threshold, it is determined that the window area to be detected is contaminated; Or a certain measurement time period is set, and the average value of the weighted sums calculated multiple times within the calculation period is calculated. If the average value of the weighted sum is greater than a preset weighted sum threshold, it is determined that the window area to be detected is contaminated.

2. The optical window contamination detection method for laser radar according to claim 1, characterized in that: The main laser radar system includes: A first transmitting unit configured to transmit a first laser pulse; a first receiving unit, configured to receive a first echo pulse corresponding to the first laser pulse, and convert the optical signal into an electrical signal; The main system data processing unit is configured to obtain the number of echo pulses, the echo pulse width and the echo front threshold time by setting a threshold comparator according to the electrical characteristics of the first echo pulse; A scanning unit is configured to drive and control the radar motor plus the rotating mirror structure to rotate the radar at a set speed to achieve radar scanning; The main control unit is used to control the radar's laser pulse emission, echo pulse reception, echo pulse data processing, and the timing and logical relationship between the three.

3. The optical window contamination detection method for laser radar according to claim 1, characterized in that: Each optical sub-circuit includes: a second emitting unit configured to emit a second laser pulse; The second receiving unit is configured to receive a second echo pulse corresponding to the second laser pulse and convert the optical signal into an electrical signal.

4. The optical window contamination detection method for laser radar according to claim 1, characterized in that: The optical sub-circuit and the laser radar main system work in different areas and time periods: when the laser radar main system scans to angle A, the optical sub-circuit within the range of A+180°±B starts to work, and the time when the optical sub-circuit emits laser pulses is separated from the time when the laser radar main system emits laser pulses; where B is a preset angle value.

5. The optical window contamination detection method for laser radar according to claim 1, characterized in that: The area where the laser radar's optical window is contaminated is determined by the scanning azimuth corresponding to the echo and the window position corresponding to the optical sub-circuit, including: Determine the corresponding window area according to the scanning azimuth angle corresponding to the echo, and combine it with the corresponding window position of the optical sub-circuit, and take the intersection of the two as the window area to be detected; The union of multiple window areas to be detected that are judged to be contaminated is taken to obtain the area where the optical window of the laser radar is contaminated.

6. The optical window contamination detection method for laser radar according to claim 5, characterized in that: The optical window pollution type of the lidar is determined by the echo pulse width, echo front threshold time and echo amplitude ratio, including: Pollution types include uniform pollution and point pollution; If the echo pulse widths and echo front threshold moments corresponding to different scanning angles of the laser radar main system are similar, and the echo amplitude ratios of multiple optical sub-circuits of the auxiliary window detection system are similar, it is determined to be uniformly contaminated; If the echo pulse width of the lidar main system at a specific angle is greater than that in other directions, and the echo front threshold time is earlier than that in other directions, and the echo amplitude ratio of the auxiliary window detection system at the same angle is lower than that in other directions, it is judged as point pollution.

7. The optical window contamination detection method for laser radar according to claim 6, characterized in that: The degree of optical window contamination of the lidar is determined by the echo pulse width and the echo amplitude ratio, including: For a certain window area to be detected, a first pollution degree is determined by the echo pulse width, and a second pollution degree is determined by the echo amplitude ratio; Setting a third weight for the first pollution degree and a fourth weight for the second pollution degree; wherein the third weight is greater than the fourth weight; The pollution degree of the window area to be detected is jointly determined by calculating the weighted sum of the first pollution degree and the second pollution degree.

8. The optical window contamination detection method for laser radar according to claim 7, characterized in that: The optical window pollution change trend of the laser radar is determined by the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and the corresponding window position and echo amplitude ratio of the optical sub-circuit, including: Through the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and optical sub-circuit corresponding window position and echo amplitude ratio in multiple measurement time periods, the presence or absence of optical window pollutants, the pollution area, pollution type and pollution degree of the lidar in multiple measurement time periods are determined, and finally the change trend of optical window pollution of the lidar is determined.

9. A laser radar, characterized in that: The laser radar includes a main laser radar system and an auxiliary window detection system. The laser radar realizes optical window pollution detection of the laser radar based on the main laser radar system and the auxiliary window detection system, including: The laser radar main system emits a first laser pulse and receives a corresponding first echo pulse, obtains the number of echo pulses, the echo pulse width and the echo front threshold time through the first echo pulse, and determines the scanning azimuth corresponding to the echo; each scanning azimuth corresponds to an optical window area of ​​a specific angle; The auxiliary window detection system includes a plurality of optical sub-circuits and an auxiliary system data processing unit, each of which corresponds to a fixed optical window area at a specific angle; each of which emits a second laser pulse and receives a corresponding second echo pulse; wherein the laser wavelengths of the first laser pulse and the second laser pulse are different; the auxiliary system data processing unit is configured to obtain a corresponding echo amplitude ratio according to the electrical characteristics of the second echo pulse; wherein the echo amplitude ratio is a ratio of an echo amplitude under an actual working state to an echo amplitude under an ideal pollution-free state; The presence of pollutants in the optical window of the laser radar, the area where the pollution is located, the type of pollution, the degree of pollution and the trend of pollution change are determined through the number of echo pulses, the width of echo pulses, the threshold time of the echo front edge, the scanning azimuth corresponding to the echo, and the window position and echo amplitude ratio corresponding to the optical sub-circuit. Among them, the presence or absence of optical window contamination of the laser radar is determined by the number of echo pulses, echo pulse width, echo front threshold time and echo amplitude ratio, including: For a certain window area to be detected, if the number of echo pulses is greater than the preset number threshold, the laser radar main system determines that there is pollution; at this time, if the echo pulse width is greater than the preset pulse width threshold or the echo front threshold time is earlier than the preset time threshold, the laser radar main system further determines that there must be pollution; If the number of echo pulses is equal to the preset number threshold, and the echo front threshold time is earlier than the preset time threshold, the laser radar main system determines that there is contamination; If the echo amplitude ratio is lower than the preset threshold, the auxiliary window detection system determines that there is contamination; If it is determined that there is contamination, the first determination value is output; if it is determined that there must be contamination, the second determination value is output, and the first determination value is no longer output at this time; wherein the first determination value is smaller than the second determination value; Setting a first weight and a second weight for the laser radar main system and the auxiliary window detection system respectively; wherein the first weight is greater than the second weight; Calculate the weighted sum of the judgment values ​​output by the laser radar main system and the auxiliary window detection system. If the weighted sum is greater than a preset weighted sum threshold, it is determined that the window area to be detected is contaminated; Or a certain measurement time period is set, and the average value of the weighted sums calculated multiple times within the calculation period is calculated. If the average value of the weighted sum is greater than a preset weighted sum threshold, it is determined that the window area to be detected is contaminated.

10. The laser radar according to claim 9, characterized in that: The main laser radar system includes: A first transmitting unit configured to transmit a first laser pulse; a first receiving unit, configured to receive a first echo pulse corresponding to the first laser pulse, and convert the optical signal into an electrical signal; The main system data processing unit is configured to obtain the number of echo pulses, the echo pulse width and the echo front threshold time by setting a threshold comparator according to the electrical characteristics of the first echo pulse; A scanning unit is configured to drive and control the radar motor plus the rotating mirror structure to rotate the radar at a set speed to achieve radar scanning; The main control unit is used to control the radar's laser pulse emission, echo pulse reception, echo pulse data processing, and the timing and logical relationship between the three.

11. The laser radar according to claim 9, characterized in that: Each optical sub-circuit includes: a second emitting unit configured to emit a second laser pulse; The second receiving unit is configured to receive a second echo pulse corresponding to the second laser pulse and convert the optical signal into an electrical signal.

12. The laser radar according to claim 9, characterized in that: The optical sub-circuit and the laser radar main system work in different areas and time periods: when the laser radar main system scans to angle A, the optical sub-circuit within the range of A+180°±B starts to work, and the time when the optical sub-circuit emits laser pulses is separated from the time when the laser radar main system emits laser pulses; where B is a preset angle value.

13. The laser radar according to claim 9, characterized in that: The area where the laser radar's optical window is contaminated is determined by the scanning azimuth corresponding to the echo and the window position corresponding to the optical sub-circuit, including: Determine the corresponding window area according to the scanning azimuth angle corresponding to the echo, and combine it with the corresponding window position of the optical sub-circuit, and take the intersection of the two as the window area to be detected; The union of multiple window areas to be detected that are judged to be contaminated is taken to obtain the area where the optical window of the laser radar is contaminated.

14. The laser radar according to claim 13, characterized in that: The optical window pollution type of the lidar is determined by the echo pulse width, echo front threshold time and echo amplitude ratio, including: Pollution types include uniform pollution and point pollution; If the echo pulse widths and echo front threshold moments corresponding to different scanning angles of the laser radar main system are similar, and the echo amplitude ratios of multiple optical sub-circuits of the auxiliary window detection system are similar, it is determined to be uniformly contaminated; If the echo pulse width of the lidar main system at a specific angle is greater than that in other directions, and the echo front threshold time is earlier than that in other directions, and the echo amplitude ratio of the auxiliary window detection system at the same angle is lower than that in other directions, it is judged as point pollution.

15. The laser radar according to claim 14, characterized in that: The degree of optical window contamination of the lidar is determined by the echo pulse width and the echo amplitude ratio, including: For a certain window area to be detected, a first pollution degree is determined by the echo pulse width, and a second pollution degree is determined by the echo amplitude ratio; Setting a third weight for the first pollution degree and a fourth weight for the second pollution degree; wherein the third weight is greater than the fourth weight; The pollution degree of the window area to be detected is jointly determined by calculating the weighted sum of the first pollution degree and the second pollution degree.

16. The laser radar according to claim 15, characterized in that: The optical window pollution change trend of the laser radar is determined by the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and the corresponding window position and echo amplitude ratio of the optical sub-circuit, including: Through the number of echo pulses, echo pulse width, echo front threshold time, echo corresponding scanning azimuth, and optical sub-circuit corresponding window position and echo amplitude ratio in multiple measurement time periods, the presence or absence of optical window pollutants, the pollution area, pollution type and pollution degree of the lidar in multiple measurement time periods are determined, and finally the change trend of optical window pollution of the lidar is determined.

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