Distance measuring method of large field angle laser radar, Large field angle laser radar

Abstract

The application discloses a ranging method of a large-view-angle laser radar and the large-view-angle laser radar. By selecting an arbitrary field-of-view coincidence core and applying a predetermined delay strategy to the selected field-of-view coincidence core, the large-view-angle laser radar is controlled to run, the light emission of the scanning areas corresponding to the two field-of-view coincidence cores is separated through the delay strategy, and an initial point cloud is obtained. According to the distance distribution between each point cloud and the adjacent point cloud in the initial point cloud, the interference point cloud is filtered out. After the interference point cloud is filtered out, the point clouds measured by the two optical measurement modules are spliced to complete the ranging of the large-view-angle laser radar, and the technical problem that in the prior art, the encrypted areas corresponding to the multiple cores of the large-view-angle multi-core laser radar have many noise points that are not generated from the original, which greatly affects the ranging capability of the large-view-angle laser radar is solved.

Description

Technical Field

[0001] This application relates to the field of lidar technology, and more specifically, to a ranging method for a large field-of-view lidar and a large field-of-view lidar. Background Technology

[0002] In related technologies, lidar is a radar system that detects the position, velocity, and other characteristics of a target by emitting a laser beam. Its English name, LiDAR, is an abbreviation for Light Detection and Ranging. Its core working principle is very intuitive: Emission: A short laser pulse is emitted towards the target. Reflection: The laser pulse is reflected after encountering the object. Reception: The sensor receives the returned laser signal. Calculation: By measuring the time it takes for the laser to travel from emission to return (Time of Flight, ToF), the precise distance to the target is calculated. Distance = (Speed ​​of light × Time of flight) / 2. By rapidly repeating this process millions of times and combining it with the angle information of the scanning mirror, the system can generate a high-precision 3D point cloud map of the surrounding environment.

[0003] Pulsed laser ranging radar employs a time-of-flight (TOF) ranging scheme based on pulsed lasers. The radar transmitter emits a ranging light pulse, which simultaneously triggers a timing chip as a START signal, recorded as λ. After diffuse reflection from the target, the echo pulse is detected and received by the receiver. After photoelectric conversion, it triggers a timing chip as a STOP signal, recorded as λ. This completes one ranging (timing) cycle. λ represents the flight time of the light pulse during this timing cycle. The final ranging result can be obtained by performing a time-to-distance conversion using the speed of light, where λ represents the speed of light in the current medium. The entire process is shown in Figure 1.

[0004] In related technologies, to cope with complex urban scenarios and "ghost pedestrian" situations, wide field-of-view LiDAR is needed to support these scenarios. A wide field of view can form a blind-spot-free protection circle around the vehicle, detecting objects from the side or rear before they enter the collision path, buying valuable reaction time for the decision-making system. This is something forward-facing narrow field-of-view radar simply cannot do. Meanwhile, high-level autonomous driving (L4 and above) has extremely high safety standards, requiring multiple redundant perception systems. Cameras and millimeter-wave radars may have limitations (e.g., cameras are affected by lighting conditions, and millimeter-wave radar has low angular resolution). One or more wide field-of-view LiDARs can provide independent, stable, and high-precision 3D panoramic coverage, serving as a "source of truth" and redundant backup for other sensors, ensuring basic safety perception capabilities even if any sensor fails.

[0005] In summary, wide field-of-view lidar plays a crucial role in certain specific application scenarios. Typically, wide field-of-view lidar uses multiple measurement modules to achieve a large field of view in both the horizontal and vertical directions. However, in the dense areas of wide field-of-view lidar, when different measurement modules maintain synchronous measurement, multiple non-real measurement echoes exist simultaneously due to the reflection characteristics of light, also known as point clouds. These point clouds significantly affect the ranging capability of wide field-of-view lidar.

[0006] No effective solutions have yet been proposed to address the aforementioned problems in the relevant technologies. Summary of the Invention

[0007] The main objective of this application is to provide a ranging method and a wide field-of-view lidar, in order to solve the technical problem in the prior art of wide field-of-view multi-core lidar where many arbitrary noise points appear in the encrypted area corresponding to multiple cores, which greatly affects the ranging capability of the wide field-of-view lidar.

[0008] According to one aspect of this application, a ranging method for a wide field-of-view lidar is provided. The wide field-of-view lidar includes two optical measurement modules, each containing two sensors. The detection field of view of one sensor in the overlapping field-of-view module coincides with the detection field of view of one sensor in the other optical measurement module. The ranging method includes: selecting any one of the overlapping sensors and applying a predetermined delay strategy to the selected sensor; controlling the operation of the wide field-of-view lidar to achieve emission separation of the scanning areas corresponding to the two overlapping sensors through the delay strategy, and obtaining an initial point cloud; filtering out interfering point clouds according to the distance distribution between each point cloud and its adjacent point clouds in the initial point cloud; and stitching together the point clouds measured by the two optical measurement modules after filtering out the interfering point clouds to complete the ranging of the wide field-of-view lidar.

[0009] In one alternative embodiment, a predetermined delay strategy is applied to the selected field-of-view coincidence mechanism, including: binding a distance feature to each emitting unit of the laser of the selected field-of-view coincidence mechanism.

[0010] In one optional embodiment, the field-of-view overlap mechanism includes a laser array composed of M rows * N columns of light-emitting units. Each light-emitting unit of the field-of-view overlap mechanism is bound to a distance feature. The mechanism further includes: applying a light-emitting trigger delay to each light-emitting unit in the laser array; wherein the delay time corresponding to the light-emitting trigger delay applied to each light-emitting unit in the same row varies according to a first preset rule, wherein the first preset rule is that the delay times corresponding to at least the first m light-emitting units are different, m ≤ M; the delay time applied to each light-emitting unit in the same column varies according to a second preset rule, wherein the second preset rule is that the delay times corresponding to at least the first n light-emitting units are different, n ≤ N; after each delay time, the corresponding light-emitting unit is triggered to emit a laser pulse, and after the echo of the returned laser pulse is received by the receiving unit, the distance feature bound to each light-emitting unit is calculated based on the light-emitting trigger delay.

[0011] In one optional embodiment, the delay time interval between two adjacent light-emitting units in each row is an integer multiple of 10 ns, and the delay time interval between two adjacent light-emitting units in each column is an integer multiple of 10 ns. Interference point clouds are filtered out according to the distance distribution between each point cloud and its adjacent point clouds in the initial point cloud. This includes: selecting any point in the initial point cloud as the point cloud to be detected, and determining the adjacent point clouds corresponding to the point cloud to be detected; based on the ranging value corresponding to the point cloud to be detected and the ranging values ​​corresponding to the adjacent point clouds, determining the point clouds whose ranging values ​​match the beat characteristics formed by the light-emitting trigger delay corresponding to the light-emitting unit as interference point clouds and filtering them out, thus obtaining the remaining point cloud; and screening isolated points in the remaining point cloud, determining the isolated points as interference point clouds and filtering them out.

[0012] In one optional embodiment, based on the ranging value corresponding to the point cloud to be detected and the ranging values ​​corresponding to adjacent point clouds, the point cloud whose ranging value matches the beat characteristic formed by the light emission trigger delay corresponding to the light emission unit is identified as an interfering point cloud and filtered out, including: when the number of adjacent point clouds is less than or equal to 4, calculating the reference ranging value corresponding to the point cloud to be detected and the ranging values ​​corresponding to adjacent point clouds respectively; when the reference ranging value is a multiple of 1.5m and the ranging values ​​corresponding to adjacent point clouds are all multiples of 1.5m, determining that the point cloud to be detected is an interfering point cloud and filtering out the interfering point cloud.

[0013] In one optional embodiment, filtering out isolated points in the remaining point cloud as interfering point clouds includes: taking any one point cloud in the remaining point cloud as the point cloud to be detected, and obtaining the projected coordinates of the point cloud to be detected on a preset two-dimensional plane; wherein the preset two-dimensional plane is composed of a horizontal direction and a vertical direction; taking the point cloud to be detected as the center, in the horizontal direction, the four point clouds with the smallest absolute value of the difference between the projected coordinates and the x-coordinates of the point cloud to be detected are determined as horizontally adjacent point clouds; wherein the horizontally adjacent point clouds are evenly distributed on the left and right sides of the point cloud to be detected; in the vertical direction, the projected coordinates and the x-coordinates of the point cloud to be detected are determined as horizontally adjacent point clouds. The four point clouds with the smallest absolute difference in the ordinate of the projected coordinates of the point cloud to be detected are identified as vertically adjacent point clouds. These vertically adjacent point clouds are located above and below the point cloud to be detected, respectively. The horizontal distance difference between the distance measurement value corresponding to each horizontally adjacent point cloud and the distance measurement value corresponding to the point cloud to be detected is calculated. The vertical distance difference between the distance measurement value corresponding to each vertically adjacent point cloud and the distance measurement value corresponding to the point cloud to be detected is also calculated. If each horizontal distance difference and each vertical distance difference is greater than 1.5m, the point cloud to be detected is identified as an isolated point, and this isolated point is identified as an interfering point cloud, which is then filtered out.

[0014] This application also provides a large field-of-view lidar, which includes: two optical measurement modules, each comprising two cores, a rotating mirror, and a control module; each optical measurement module includes a field-of-view overlap core that overlaps with one core in the other optical measurement module; a main control module connected to the two optical measurement modules, used to receive point cloud data transmitted from the two optical measurement modules and to parse and output the point cloud data; the large field-of-view lidar is used to execute the ranging method of the large field-of-view lidar of claim 1.

[0015] In one optional embodiment, the wide field-of-view lidar further includes a window heating module connected to the main control module. The window heating module is used to collect the real-time temperature of the window and heat the window when the temperature of the window is within a predetermined range.

[0016] In one optional embodiment, the wide field-of-view lidar further includes a constant temperature heating module, which includes a constant temperature heating element and is connected to the main control module. The constant temperature heating module is used to collect the cavity temperature of the wide field-of-view lidar and, when the cavity temperature is within a specific temperature range, raises the temperature of the cavity through the constant temperature heating element.

[0017] In one optional embodiment, the wide field-of-view lidar further includes a window dirt detection module connected to the main control module, used to detect the dirt status of the lidar's window and report the dirt status.

[0018] In this application, an electronic device is also provided, which includes a wide field-of-view lidar according to any one of claims 7 to 10.

[0019] This application provides a ranging method for a large field-of-view lidar. It involves selecting any one overlapping camera module and applying a predetermined delay strategy to it; controlling the operation of the large field-of-view lidar; using the delay strategy to separate the light emission of the scanning areas corresponding to the two overlapping camera modules, thus obtaining an initial point cloud; filtering out interfering point clouds according to the distance distribution between each point cloud and its adjacent point clouds; and stitching together the point clouds measured by the two optical measurement modules to complete the ranging of the large field-of-view lidar. This solves the technical problem in related technologies where large field-of-view multi-camera lidars often have numerous artificial noise points in the encrypted areas corresponding to multiple camera modules, significantly affecting the ranging capability of the large field-of-view lidar. This method achieves improved ranging capability and accuracy of the large field-of-view lidar while maintaining the large field of view ranging capability. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, are illustrative and descriptive of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of a time-of-flight (TOF) ranging scheme based on pulsed laser for lidar. Figure 2 A schematic diagram of a ranging method for a large field-of-view lidar provided in an embodiment of this application; Figure 3 A schematic diagram of the core module of a large field-of-view lidar provided in this application embodiment; Figure 4 A schematic diagram illustrating an embodiment of the delay time of a laser array light-emitting unit provided in this application; Figure 5 A schematic diagram of an embodiment of the emission delay time of an optional light-emitting unit in a laser array provided in this application; Figure 6 A schematic diagram of a point cloud to be detected and four adjacent point clouds provided for an embodiment of this application; Figure 7 A schematic diagram of the point cloud to be detected and its eight adjacent point clouds provided in an embodiment of this application; Figure 8 This is a schematic diagram of the point cloud effect provided in the embodiments of this application; Figure 9 A schematic diagram of data transmission and signal control for a large field-of-view lidar provided in an embodiment of this application; Figure 10 A schematic diagram of the transceiver mechanism provided for an optional embodiment of this application; Figure 11 The rotating mirror diagram provided in this application embodiment; Figure 12 This is a schematic diagram showing the angle information of the three mirror surfaces of the rotating mirror provided in an embodiment of this application. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application: VCSEL (Vertical-Cavity Surface-Emitting Laser): A more "modern" type of laser where the laser beam is emitted vertically from the top surface of a semiconductor chip. It can be understood as the laser oscillating up and down within a "vertical miniature resonant cavity" before exiting from the ceiling. Advantages: High beam quality: Circularly symmetrical spot size, small divergence angle, easy collimation and optical design. Easy to form large-scale two-dimensional arrays: Tens of thousands to millions of laser units can be fabricated on a chip. Low cost: Full-process testing can be performed at the wafer level, significantly reducing production costs and scrap rates. Low threshold current, low power consumption. Easy to couple with fiber optics or other optical components. Operates over a wide temperature range without a TEC (for many consumer applications).

[0025] APD (Avalanche Photodiode): With the development of weak light detection technology and fiber optic communication technology, avalanche photodiodes (APDs) have attracted widespread attention. APDs, with their unique advantages—insensitivity to magnetic fields, low power consumption, small size, wide operating frequency range, and low operating voltage—have become a research hotspot in the field of optoelectronics. They have found important applications in high-resolution spectral measurement, non-destructive material analysis, bioluminescence, radiation detection, high-energy physics, astronomical photometry, optical time-domain reflectometry, and quantum key distribution systems, greatly promoting the progress of modern science and technology and the rapid development of society and the economy. An avalanche photodiode (APD) is a photosensitive element used in laser communication. When a reverse bias voltage is applied to the PN junction of a photodiode made of silicon or germanium, the incident light is absorbed by the PN junction, forming a photocurrent. When the receiving end receives the measured optical signal, a current signal is generated. The stronger the returned light, the longer the current signal lasts (as shown in the figure, a strong current signal lasted for nearly 90 ns); the weaker the returned light, the shorter the current signal duration.

[0026] LiDAR scanning system: The scanning system is the "command stick" of the LiDAR, which determines how the laser beam covers the target area. It directly affects the radar's field of view, resolution, reliability, cost and size. It is responsible for guiding the laser beam in different directions and, by controlling the deflection of the beam, realizing point-by-point or parallel scanning of a specific spatial area (field of view, FOV), and finally constructing a three-dimensional point cloud.

[0027] See Figure 2 As shown, this application provides a ranging method for a wide field-of-view lidar. This method is applied to a wide field-of-view lidar, which includes two optical measurement modules. Each optical measurement module contains two sensors, with the detection field of view of one sensor in one optical measurement module coinciding with the detection field of view of one sensor in the other optical measurement module. This application provides a wide field-of-view lidar that employs a multi-optical-mechanical system for synchronous detection. That is, to achieve a wide field-of-view measurement for the entire system, multiple sets of optical transceiver modules and multiple scanning modes are used, and measurement synchronization is achieved through precise algorithm control.

[0028] Specifically, such as Figure 3 As shown, Figure 3 A schematic diagram of a large field-of-view lidar core module is shown. This core module includes two optical measurement modules, each containing two cores, a rotating mirror, and a control module. The two optical measurement modules are connected to the main control module. The dual measurement modules are responsible for acquiring and fusing point cloud data over the large field of view and filtering interference in encrypted areas by controlling the pulsed emission. Figure 3 As shown, mechanism 2 and mechanism 3 are mechanisms with overlapping fields of view. The two mechanisms have the same field of view, which leads to a lot of interfering point clouds.

[0029] Specifically, the distance measurement method provided in this application includes the following steps: S201: Select any field-of-view overlapping camera module and apply a predetermined delay strategy to the selected field-of-view overlapping camera module; in such cases... Figure 3 In the schematic diagram shown, movement 2 and movement 3 are movements with overlapping fields of view, and a predetermined delay strategy can be applied to either movement 2 or movement 3.

[0030] S202: Controls the operation of the large field-of-view lidar, and achieves emission separation of the scanning areas corresponding to the overlapping cores of the two fields of view through a delay strategy, and obtains the initial point cloud; S203: Filter out interfering point clouds according to the distance distribution between each point cloud and its neighboring point clouds in the initial point cloud; S204: After filtering out the interference point cloud, the point clouds measured by the two optical measurement modules are stitched together to complete the ranging of the large field of view lidar.

[0031] By applying the above steps to a field-of-view overlapping mechanism, a predetermined delay strategy is applied to control the pulse emission to filter out interference in the encrypted area, thereby improving the ranging capability and accuracy of the large field-of-view lidar.

[0032] In one alternative embodiment, a predetermined delay strategy is applied to the selected field-of-view coincidence mechanism, including: binding a distance feature to each emitting unit of the laser of the selected field-of-view coincidence mechanism.

[0033] The wide field-of-view lidar provided in this application generates noise points out of thin air because the detection fields of the two scanning modules overlap. One of the optical measurement modules may receive the reflected laser light emitted by the other module due to the diffuse reflection of light. This generates noise points out of thin air while generating point clouds. By binding distance features to each light-emitting unit, the reflected light that is not emitted by that laser unit can be identified, thereby identifying the noise points out of thin air.

[0034] In one optional embodiment, the field-of-view overlap mechanism includes a laser array composed of M rows * N columns of light-emitting units. Each light-emitting unit of the field-of-view overlap mechanism is bound to a distance feature. The mechanism further includes: applying a light-emitting trigger delay to each light-emitting unit in the laser array; wherein the delay time corresponding to the light-emitting trigger delay applied to each light-emitting unit in the same row varies according to a first preset rule, wherein the first preset rule is that the delay times corresponding to at least the first m light-emitting units are different, m ≤ M; after the light-emitting timing of each light-emitting unit begins, a regularly varying delay is added, and after the delay time, the laser is controlled to actually emit light.

[0035] The delay time applied to each light-emitting unit in the same column varies according to a second preset rule, wherein the delay time corresponding to at least the first n light-emitting units is different, and n≤N; similarly, in the laser array, a regularly varying delay is applied, and after the delay time, the light-emitting unit is controlled to emit light.

[0036] After their respective delay times, the corresponding light-emitting unit is triggered to emit a laser pulse. Once the echo of the returned laser pulse is received by the receiving unit, the distance characteristic associated with each light-emitting unit is calculated based on the emission trigger delay. After each light-emitting unit actually emits light, the distance data corresponding to that unit is obtained based on the reflected light received by the receiving unit. This distance data is then subtracted from the distance error introduced by the delay to obtain the true distance data. If the receiving unit corresponding to that light-emitting unit receives the echo information from lasers emitted by other lasers, the distance measurement of any unit other than its own will be abnormal due to the delay. The formula for calculating the true distance is: True distance = Radar detection distance - Delay time * Speed ​​of light. In one optional embodiment, the time interval between two adjacent light-emitting units in each row is an integer multiple of 10 ns, and the time interval between two adjacent light-emitting units in each column is an integer multiple of 10 ns. Since the ranging data corresponding to every 10 ns time interval is 1.5m, in the embodiment provided in this application, the regular variation between the light-emitting units in each row and each column is an integer multiple of 10 ns, specifically as follows: Figure 4 As shown, taking a column of light-emitting units as an example, the delay time of light-emitting unit 1 is 0, that is, 0ns is the actual light-emitting time of light-emitting unit 1. The delay time of light-emitting unit 2 is 80ns, that is, 0ns is the timing time of light-emitting unit 2, and 80ns is the actual light-emitting time of light-emitting unit 2. The delay time of light-emitting unit 3 is 40ns, the delay time of light-emitting unit 4 is 100ns, ... the delay time of light-emitting unit 9 is 0ns. That is, the delay time of light-emitting units 1-8 shown in the figure follows the second preset rule, which changes as follows: 0ns, 80ns, 40ns, 100ns, 20ns, 120ns, 60ns, 140ns. From light-emitting unit 9 onwards, the rule of light-emitting units 1-8 is followed. It should be noted that there must be at least 4 different delay times in each row and at least 4 different delay times in each column. Figure 4In the illustrated embodiment, there are eight light-emitting units with different delay times. It should be noted that, for example, the first eight light-emitting units maintain different light emission delay times for each unit, namely 0ns, 80ns, 40ns, 100ns, 20ns, 120ns, 60ns, and 140ns. Starting from the ninth unit, the light emission pattern of the first eight units is followed, namely 0ns, 80ns, 40ns, 100ns, 20ns, 120ns, 60ns, and 140ns, and so on. This is to ensure that the probability of the nearest adjacent light-emitting unit receiving a return wave with the same distance characteristics is minimized, thereby improving the ranging accuracy of the wide field-of-view lidar.

[0037] It should be noted that different delay times should be at least 4 rows and / or 4 columns to ensure that 4 rows or 4 columns form a loop, thus ensuring the effectiveness of subsequent filtering of interfering point clouds. Figure 5 A schematic diagram illustrating the emission delay time of an optional light-emitting unit in a medium-sized laser array, as provided in this application, is shown below. Figure 5 As shown, in each column of light-emitting units, the delay time of the first 8 light-emitting units is different, and the delay time of every 8 light-emitting units is a cycle. In each row of light-emitting units, the delay time of every 8 light-emitting units is different.

[0038] It should also be noted that the above embodiment is an embodiment in which only one optical measurement module adopts a fixed time interval for light emission. This application also includes an embodiment in which two optical measurement modules adopt different light emission intervals and different fixed time intervals, so as to ensure that the delay information carried by the echo corresponding to the light emission unit that may collide is different, that is, the distance measurement value of the same object is different.

[0039] According to the distance distribution between each point cloud and its neighboring point clouds in the initial point cloud, interfering point clouds are filtered out, including: selecting any point in the initial point cloud as the point cloud to be detected, and determining the neighboring point clouds corresponding to the point cloud to be detected; based on the ranging value corresponding to the point cloud to be detected and the ranging values ​​corresponding to the neighboring point clouds, point clouds whose ranging values ​​match the beat characteristics formed by the light emission trigger delay corresponding to the light emission unit are identified as interfering point clouds and filtered out, resulting in the remaining point cloud; and screening isolated points in the remaining point cloud, identifying isolated points as interfering point clouds and filtering them out. In the embodiments provided in this application, two filtering processes are used to filter out as many non-existent noise points as possible, and the point clouds that match the light emission beat characteristics and the isolated point clouds are filtered out in two separate processes.

[0040] In one optional embodiment, based on the ranging value corresponding to the point cloud to be detected and the ranging values ​​corresponding to adjacent point clouds, point clouds whose ranging values ​​conform to the rhythmic characteristics formed by the emission trigger delay corresponding to the emitting unit are identified as interfering point clouds and filtered out. This includes: when the number of adjacent point clouds is less than or equal to 4, calculating the reference ranging value corresponding to the point cloud to be detected and the ranging values ​​corresponding to the adjacent point clouds respectively; when the reference ranging value is a multiple of 1.5m and the ranging values ​​corresponding to the adjacent point clouds are all multiples of 1.5m, the point cloud to be detected is identified as an interfering point cloud and filtered out. In this embodiment, the emission interval of the emitting unit is an integer multiple of 10ns. When the ranging values ​​of the point cloud to be detected and the adjacent point clouds are both multiples of 1.5m, it means that the point cloud to be detected conforms to the emission rhythm and is identified as an interfering point cloud and filtered out. Figure 6 This is a schematic diagram of a point cloud to be detected and four adjacent point clouds provided in an embodiment of this application.

[0041] In one optional embodiment, filtering out isolated points in the remaining point cloud as interfering point clouds includes: taking any one point cloud in the remaining point cloud as the point cloud to be detected, and obtaining the projected coordinates of the point cloud to be detected on a preset two-dimensional plane; wherein the preset two-dimensional plane is composed of a horizontal direction and a vertical direction; taking the point cloud to be detected as the center, in the horizontal direction, the four point clouds with the smallest absolute value of the difference between the projected coordinates and the x-coordinates of the point cloud to be detected are determined as horizontally adjacent point clouds; wherein the horizontally adjacent point clouds are evenly distributed on the left and right sides of the point cloud to be detected; in the vertical direction, the projected coordinates and the x-coordinates of the point cloud to be detected are determined as horizontally adjacent point clouds. The four point clouds with the smallest absolute difference in the ordinate of the projected coordinates of the point cloud to be detected are identified as vertically adjacent point clouds. These vertically adjacent point clouds are located above and below the point cloud to be detected, respectively. The horizontal distance difference between the distance measurement value corresponding to each horizontally adjacent point cloud and the distance measurement value corresponding to the point cloud to be detected is calculated. The vertical distance difference between the distance measurement value corresponding to each vertically adjacent point cloud and the distance measurement value corresponding to the point cloud to be detected is also calculated. If each horizontal distance difference and each vertical distance difference is greater than 1.5m, the point cloud to be detected is identified as an isolated point, and this isolated point is identified as an interfering point cloud, which is then filtered out. In this embodiment, the delay time interval between the light-emitting units is an integer multiple of 10ns. The distance difference between the four point clouds in the horizontal direction and the four point clouds in the vertical direction of the point cloud to be detected and the point cloud to be detected is used to determine whether the point cloud to be detected is an interfering point cloud. If the distance difference between the eight point clouds and the point cloud to be detected is greater than 1.5m, the point cloud to be detected is determined to be an interfering point cloud and is filtered out. Figure 7 This is a schematic diagram of the point cloud to be detected and its eight adjacent point clouds provided in an embodiment of this application.

[0042] Figure 8 This is a schematic diagram of the point cloud effect provided in an embodiment of this application. Figure 8A represents the interference point cloud generated by the overlapping field-of-view mechanism of the large field-of-view lidar. Figure 8 B is a schematic diagram showing how the point cloud is broken up after one of the optical measurement modules introduces a regular delayed emission. Figure 8 C represents the point cloud image that reflects the real scene after filtering out interfering point clouds using the introduced filtering algorithm. Figure 8 As can be seen, after introducing the noise filtering method of this application, the noise that is not created is basically completely filtered out, which shows that the efficiency of the filtering method is extremely high.

[0043] In this application, when multiple optical measurement modules are included, and each optical measurement module contains a field-of-view overlap mechanism, a delay strategy is applied to any one of the field-of-view overlap mechanisms, and a mechanism for filtering out interfering point clouds based on distance characteristics is introduced, thereby achieving the technical effect of improving the ranging capability of a large field-of-view lidar.

[0044] See Figure 3 As shown, Figure 3 This application provides a schematic diagram of a large field-of-view lidar module. The large field-of-view lidar module includes two optical measurement modules, each containing two modules, a rotating mirror, and a control module. Each optical measurement module includes a field-of-view overlap module that overlaps with one module in the other optical measurement module. A main control module is connected to the two optical measurement modules and is used to receive point cloud data transmitted from the two modules and to parse and output the point cloud data. The large field-of-view lidar is used to execute the aforementioned large field-of-view lidar ranging method.

[0045] like Figure 9 As shown, Figure 9 This diagram illustrates the data transmission and signal control of a wide field-of-view lidar system provided in this embodiment. Optical measurement module 1 and optical measurement module 2 are separated into independent subsystems, performing control of transmission and reception and preliminary data processing. Data is transmitted to the main control module via a network port, where it is then stitched together and transmitted. The main control module also handles data acquisition and control for all peripheral modules.

[0046] like Figure 10 As shown, Figure 10 The diagram below shows the transceiver of the core provided in an optional embodiment of this application. In this embodiment, each core includes 32 lasers and 32 receiving channels. The 32 lasers emit light sequentially to complete the measurement of a line of point clouds. The emission angle of the four cores is controlled by two rotating mirrors. The rotating mirrors complete one frame of point cloud measurement in one revolution.

[0047] This application also provides a rotating mirror comprising three sides, such as... Figure 11 As shown, Figure 11The rotating mirror diagram provided in this application illustrates that horizontal point cloud scanning is completed by rotating the mirror. The rotating mirror includes a rotating mirror surface A, a rotating mirror surface B, and a rotating mirror surface C.

[0048] In the wide field-of-view lidar provided in this application, a single frame of point cloud is output by four cores and two rotating mirrors. Each rotation of the rotating mirror completes measurements on three of the three mirror surfaces. The main control module stitches and outputs the single frame of point cloud data. Specifically, as follows... Figure 12 As shown, Figure 12 This is a schematic diagram showing the angle information of the three mirror surfaces of the rotating mirror provided in an embodiment of this application.

[0049] Point clouds from surfaces A and B of the dual-core laser were selected as measurement point cloud data, and point clouds from surface C of the dual-core laser were selected as point cloud data for close-range measurement (the radar blind zone was reduced by lowering the laser's emission power and the receiver's detection threshold).

[0050] In one optional embodiment, the wide field-of-view lidar further includes a window heating module connected to the main control module. The window heating module is used to collect the real-time temperature of the window and heat the window when the window temperature is within a predetermined range. Figure 10 As shown, the wide field-of-view lidar also includes a window heating module for heating the window in case of fogging and / or low temperature.

[0051] In one optional embodiment, the wide field-of-view lidar further includes a constant-temperature heating module, comprising a constant-temperature heating element, connected to the main control module. The constant-temperature heating module is used to collect the cavity temperature of the wide field-of-view lidar and, when the cavity temperature is within a specific range, raises the cavity temperature using the constant-temperature heating element. Figure 10 As shown, the lidar also has a constant temperature heating element installed at the optical window to keep the cavity temperature of the optical window constant.

[0052] Optionally, the large field-of-view lidar provided in this application also includes other cavity temperature acquisition modules for acquiring the temperature of other cavities, including the optical window, such as acquiring the cavity temperatures corresponding to optical measurement module 1 and optical measurement module 2.

[0053] In one optional embodiment, the wide field-of-view lidar further includes a window contamination detection module connected to the main control module. This module detects the contamination status of the lidar's window and reports the status. The lidar also includes a self-cleaning module, which, upon receiving a report of window contamination, controls the main control module to clean the window to ensure effective laser transmission and reception.

[0054] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: (1) The large field of view lidar of the multi-laser system provided in this application realizes a large field of view of 120°*105° in the horizontal direction and a densified area of ​​35° in the vertical direction.

[0055] (2) Synchronous detection of multiple laser systems in a large field of view lidar: In order to achieve a large field of view measurement of the whole system, multiple sets of optical transceiver modules and multiple scanning modes are adopted, and the measurement is synchronized through precise algorithm control.

[0056] (3) Synchronous and accurate measurement in the encrypted area of ​​the large field of view lidar: In the encrypted area of ​​the field of view, different modules maintain synchronous measurement. Due to the reflection characteristics of light, there are multiple non-real measurement echoes at the same time. Accurate measurement is achieved by adjusting the emission rhythm and verifying adjacent echoes.

[0057] (4) Stability and reliability: The radar optical system and mechanical motion system with a large field of view are arranged separately, which greatly improves the stability of the system. The reliability of the system is further improved by the temperature control system of the lidar.

[0058] This application provides an electronic device that includes a wide field-of-view lidar.

[0059] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0060] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0061] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0062] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0063] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0064] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0065] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0066] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0067] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0068] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A ranging method for a large field-of-view lidar, characterized in that, The wide field-of-view lidar includes two optical measurement modules, each containing two sensors. The detection field of view of one sensor in the one optical measurement module coincides with the detection field of view of one sensor in the other optical measurement module. The ranging method includes: Select any one of the field-of-view overlapping mechanisms and apply a predetermined delay strategy to the selected field-of-view overlapping mechanism; Control the operation of the large field-of-view lidar, and use the delay strategy to achieve emission separation of the scanning areas corresponding to the two overlapping fields of view modules, and obtain the initial point cloud; According to the distance distribution between each point cloud and its neighboring point clouds in the initial point cloud, filter out interfering point clouds; After filtering out the interfering point clouds, the point clouds measured by the two optical measurement modules are stitched together to complete the ranging of the large field-of-view lidar.

2. The ranging method of a large field-of-view lidar according to claim 1, characterized in that, Applying a predetermined delay strategy to the selected field-of-view overlap mechanism includes: Bind a distance feature to each emitting unit of the laser in the selected field-of-view coincident mechanism.

3. The ranging method of a large field-of-view lidar according to claim 2, characterized in that, The field-of-view overlap mechanism includes a laser array composed of M rows * N columns of light-emitting units, and assigns a distance feature to each light-emitting unit of the field-of-view overlap mechanism, and further includes: Apply a light-emitting trigger delay to each of the light-emitting units in the laser array; The delay time corresponding to the light emission trigger delay applied to each light-emitting unit in the same row varies according to a first preset rule, wherein the first preset rule is that the delay time corresponding to at least the first m light-emitting units is different, and m≤M; the delay time applied to each light-emitting unit in the same column varies according to a second preset rule, wherein the second preset rule is that the delay time corresponding to at least the first n light-emitting units is different, and n≤N; after their respective delay times, the corresponding light-emitting unit is triggered to emit a laser pulse, and after the echo of the laser pulse is received by the receiving unit, the distance feature bound to each light-emitting unit is calculated based on the light emission trigger delay.

4. The ranging method of a large field-of-view lidar according to claim 3, characterized in that, The delay time interval between two adjacent light-emitting units in each row is an integer multiple of 10 ns, and the delay time interval between two adjacent light-emitting units in each column is an integer multiple of 10 ns. Interference point clouds are filtered out according to the distance distribution between each point cloud and its adjacent point clouds in the initial point cloud, including: Select any point in the initial point cloud as the point cloud to be detected, and determine the adjacent point clouds corresponding to the point cloud to be detected; Based on the ranging value corresponding to the point cloud to be detected and the ranging value corresponding to the adjacent point cloud, the point cloud whose ranging value conforms to the beat feature formed by the light emission trigger delay corresponding to the light emission unit is identified as the interference point cloud and filtered out to obtain the remaining point cloud; Isolated points in the remaining point cloud are selected, and these isolated points are identified as interference points and filtered out.

5. The ranging method of a large field-of-view lidar according to claim 4, characterized in that, Based on the ranging value corresponding to the point cloud to be detected and the ranging value corresponding to the adjacent point clouds, the point clouds whose ranging values ​​match the beat characteristics formed by the emission trigger delay corresponding to the emission unit are identified as the interfering point clouds and filtered out, including: When the number of adjacent point clouds is less than or equal to 4, the reference ranging value corresponding to the point cloud to be detected and the ranging value corresponding to the adjacent point clouds are calculated respectively. If the reference distance value is a multiple of 1.5m, and the distance values ​​corresponding to the adjacent point clouds are all multiples of 1.5m, the point cloud to be detected is determined to be an interfering point cloud, and the interfering point cloud is filtered out.

6. The ranging method of a large field-of-view lidar according to claim 4, characterized in that, Selecting isolated points from the remaining point cloud to identify and filter out interference points includes: Take any one of the remaining point clouds as the point cloud to be detected, and obtain the projection coordinates of the point cloud to be detected on a preset two-dimensional plane; wherein, the preset two-dimensional plane is composed of a horizontal direction and a vertical direction; Centered on the point cloud to be detected, in the horizontal direction, the four point clouds with the smallest absolute value of the difference between their projected coordinates and the projected coordinates of the point cloud to be detected are determined as horizontally adjacent point clouds; wherein, the horizontally adjacent point clouds are evenly distributed on the left and right sides of the point cloud to be detected. In the vertical direction, the four point clouds with the smallest absolute value of the difference between the projected coordinates and the projected coordinates of the point cloud to be detected are determined as vertically adjacent point clouds; wherein, the vertically adjacent point clouds are located above and below the point cloud to be detected, respectively. Calculate the horizontal distance difference between the ranging value corresponding to each of the horizontally adjacent point clouds and the ranging value corresponding to the point cloud to be detected; Calculate the vertical distance difference between the ranging value corresponding to each vertically adjacent point cloud and the ranging value corresponding to the point cloud to be detected; If each horizontal distance difference and each vertical distance difference is greater than 1.5m, the point cloud to be detected is determined to be an isolated point, the isolated point is determined to be an interfering point cloud, and the interfering point cloud is filtered out.

7. A wide field-of-view lidar, characterized in that, The wide field-of-view lidar includes: There are two optical measurement modules, each comprising two mechanisms, a rotating mirror, and a control module; Each of the optical measurement modules includes a field-of-view overlap mechanism that has a detection field of view overlap with one of the mechanisms in another optical measurement module; The main control module is connected to the two optical measurement modules and is used to receive point cloud data transmitted by the two optical measurement modules and parse and output the point cloud data. The wide field-of-view lidar is used to perform the ranging method of a wide field-of-view lidar as described in any one of claims 1 to 6.

8. The wide field-of-view lidar according to claim 7, characterized in that, The wide field-of-view lidar also includes a window heating module, which is connected to the main control module. The window heating module is used to collect the real-time temperature of the window and heat the window when the temperature of the window is within a predetermined range.

9. The wide field-of-view lidar according to claim 7, characterized in that, The wide field-of-view lidar also includes a constant temperature heating module, which includes a constant temperature heating element and is connected to the main control module. The constant temperature heating module is used to collect the cavity temperature of the wide field-of-view lidar and, when the cavity temperature is within a specific temperature range, raise the temperature of the cavity through the constant temperature heating element.

10. The wide field-of-view lidar according to claim 7, characterized in that, The wide field-of-view lidar also includes a window dirt detection module, which is connected to the main control module and is used to detect the dirt status of the lidar's window and report the dirt status.

11. An electronic device, characterized in that, The electronic device includes a wide field-of-view lidar as described in any one of claims 7 to 10.

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