Laser radar and its ranging method

Abstract

The present invention provides a laser radar, comprising: a transmitting unit, including a laser, which can emit multiple laser beams for target detection; a receiving unit, including a detector array, which can receive reflected echoes and convert the echoes into electrical signals; a processing unit, which can calculate the distance between the target and the laser radar according to the electrical signals output by the detector array, and when the preset conditions are met, output the electrical signals of some detectors in the detector array according to the preset mode. A method for measuring distance using a laser radar is also provided. By reducing the number of lines on close-range targets, the problem of laser radar's performance degradation in measuring close-range targets and redundancy of the number of lines at close range is improved. By utilizing the feature of high-beam laser radar's redundant number of lines at close range, when designing the laser radar, priority is given to ensuring the close-range measurement performance of some beams, and when the distance value measured by beams with poor close-range performance is within a certain specific range at close range, the measurement results of these beams are not output.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic technology, and in particular to a laser radar and a method for measuring distance using the laser radar. Background Art

[0002] In some laser radars with separate transmitters and receivers, the optical axes of the receiving lens group and the transmitting lens group do not overlap (non-coaxial). This optical structure will cause the laser radar to have a reduced measurement performance for nearby targets. This problem can only be improved to a certain extent through various optical methods, but it cannot be completely solved.

[0003] As the number of laser radar lines increases, the spatial resolution of laser radar is getting higher and higher. However, because the different lines of laser radar are radially divergent, the closer to the laser radar, the smaller the distance between different lines, and even the laser spots of adjacent beams overlap. Therefore, for nearby targets, the laser beams projected on them may be too dense and redundant.

[0004] The contents of the background technology section are merely the technologies known to the public and do not necessarily represent the existing technologies in the field. Summary of the invention

[0005] The invention provides a laser radar and a method for measuring distance using the laser radar.

[0006] According to one aspect of the present invention, a laser radar comprises:

[0007] The transmitting unit includes a laser configured to emit a plurality of laser beams for target detection;

[0008] A receiving unit, comprising a detector array, configured to receive echoes of the plurality of laser beams reflected by a target object and convert the echoes into electrical signals;

[0009] The processing unit is configured to calculate the distance between the target object and the laser radar based on the electrical signal output by the detector array, and is configured to output the electrical signals of some detectors in the detector array according to a preset mode when a preset condition is met.

[0010] According to one aspect of the present invention, the preset condition includes: the distance between the target object and the laser radar is less than a first preset value, and the laser radar further includes: a rotating shaft, the rotating shaft is located inside the laser radar;

[0011] The transmitting unit further comprises a transmitting lens, which is located downstream of the optical path of the laser and receives the multiple laser beams, modulates them and transmits them to the outside of the laser radar, and the laser array is located at the focal plane of the transmitting lens;

[0012] The receiving unit further includes a receiving lens configured to converge echoes of the multiple laser beams reflected by the target object onto the detector array, and the detector array is located at a focal plane of the receiving lens.

[0013] According to one aspect of the present invention, the detector array includes multiple columns along a first direction perpendicular to the rotation axis, each column includes at least one detector distributed parallel to the rotation axis, and the preset mode includes: when the distance between the target object and the laser radar is less than the first preset value, for the two columns of detectors in which optical crosstalk may occur in the first direction, the electrical signal of the column of detectors with a smaller distance from the rotation axis is output.

[0014] According to one aspect of the present invention, the detector array includes a plurality of detectors, and the plurality of detectors are arranged in a row parallel to the rotation axis.

[0015] According to one aspect of the present invention, the preset mode includes: when the distance between the target object and the laser radar is less than the first preset value, the processing unit outputs an electrical signal of every n detectors in the detector array in a direction parallel to the rotation axis, where n is a positive integer.

[0016] According to one aspect of the present invention, the preset mode includes: when the distance between the target object and the laser radar is less than the first preset value, the processing unit outputs the electrical signals of some detectors in the detector array in the following manner: as the distance between the target object and the laser radar decreases, the value of n increases.

[0017] According to one aspect of the present invention, the processing unit is configured to output electrical signals of some detectors in the detector array according to the preset mode when the laser radar is within a preset vertical field of view.

[0018] According to one aspect of the present invention, the emitting unit comprises a laser array formed by a single laser or a linear array laser or a planar array laser, and the laser comprises an edge emitting laser or a vertical cavity surface emitting laser.

[0019] The present invention also provides a method for measuring distance using a laser radar, wherein the laser radar comprises a transmitting unit and a receiving unit, wherein the transmitting unit comprises a laser, and the receiving unit comprises a detector array, and the method comprises:

[0020] Emitting a laser beam to the outside of the laser radar for target detection;

[0021] receiving an echo of the laser beam reflected by a target object and converting the echo into an electrical signal;

[0022] Calculating the distance between the target object and the laser radar according to the electrical signal output by the detector array;

[0023] When the preset conditions are met, the electrical signals of some detectors in the detector array are output according to a preset mode to form three-dimensional point cloud data.

[0024] According to one aspect of the present invention, the preset condition includes: the distance between the target object and the laser radar is less than a first preset value, the laser radar also includes a rotation axis, the rotation axis is located inside the laser radar, the detector array includes a plurality of columns along a first direction perpendicular to the rotation axis, each column includes at least one detector distributed parallel to the rotation axis direction,

[0025] The step of outputting the electrical signals of some detectors in the detector array according to a preset mode to form three-dimensional point cloud data when the preset conditions are met includes:

[0026] For the two columns of detectors that may cause optical crosstalk in the first direction, the electrical signal of the column of detectors that is at a smaller distance from the rotation axis is output to form three-dimensional point cloud data.

[0027] According to one aspect of the present invention, the preset conditions include: the distance between the target object and the laser radar is less than a first preset value, the detector array includes a plurality of detectors, and the plurality of detectors are arranged in a row parallel to the rotation axis direction.

[0028] According to one aspect of the present invention, when a preset condition is met, the step of outputting electrical signals of some detectors in the detector array according to a preset mode to form three-dimensional point cloud data includes:

[0029] When the distance between the target object and the laser radar is less than the first preset value, every n detectors output an electrical signal in a direction parallel to the rotation axis to form three-dimensional point cloud data, where n is a positive integer.

[0030] According to one aspect of the present invention, as the distance between the target object and the laser radar decreases, the value of n increases.

[0031] According to one aspect of the present invention, when a preset condition is met, the step of outputting electrical signals of some detectors in the array of detectors according to a preset mode to form three-dimensional point cloud data includes:

[0032] When the laser radar is within a preset vertical field of view, electrical signals of some detectors in the detector array are output according to the preset mode to form three-dimensional point cloud data.

[0033] When designing a multi-beam LiDAR, the performance of long-distance measurement is generally prioritized. The optical structure and electronic circuit design will try to make the radar achieve the highest efficiency at long distances. However, at close range, the optical efficiency of each beam will generally decrease, and the photoelectric crosstalk between the beams will increase at close range, so the close-range measurement performance of each beam will decrease to varying degrees. In order to improve the resolution at a distance, the number of laser lines will also increase. This will cause the laser beams projected on the surface of the close-range target to be very dense, and even spot stacking may occur, resulting in redundancy. At this time, some of the covered beams can be appropriately removed, leaving a suitable number of beams. When choosing which numbers to remove, you can know in advance through experiments or calculations which beams have relatively poor close-range measurement performance. Then choose a suitable line reduction rule so that as many of these channels with poor close-range performance as possible can be removed.

[0034] The method of the embodiment of the present invention is to improve the problem of laser radar performance degradation and redundancy of the number of lines at close range when measuring close-range targets by reducing the number of lines on close-range targets. The present invention utilizes the feature of high-beam laser radar with redundant lines at close range. When designing the laser radar, the close-range measurement performance of part of the beam is prioritized, and the close-range performance of the other part of the beam is sacrificed as necessary. If the distance value measured by these beams with poor close-range performance is within a certain range at close range, the measurement results of these beams are not output. In addition, if the beam distribution of the laser radar is uneven, such as being encrypted within a certain vertical field of view angle range and non-encrypted in other vertical field of view angle ranges, different line reduction rules can be formulated for beams in different vertical field of view angle intervals. Line redundancy is reduced by reducing the line of close-range targets, thereby improving detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure. In the drawings:

[0036] Figure 1 A block diagram of a laser radar according to the first aspect of the present invention is shown;

[0037] Figure 2 A schematic diagram of the appearance of a laser radar is shown;

[0038] Figure 3A A schematic diagram of a laser array and a detector array is shown;

[0039] Figure 3B shows an arrangement of a laser array according to an embodiment of the present invention;

[0040] Figure 3Cshows an arrangement of a laser array and a detector array according to another embodiment of the present invention;

[0041] Figure 4 A schematic diagram showing the drift of light spots in a laser radar is shown;

[0042] Figure 5 A schematic diagram showing the trajectory of the laser sweep when the laser radar detects a distant target;

[0043] Figure 6 A schematic diagram showing the trajectory of the laser sweep when the laser radar detects a nearby target;

[0044] Figure 7 A schematic diagram of the laser radar before and after line reduction processing is shown;

[0045] Figure 8 A schematic diagram showing a line reduction operation for a laser radar; and

[0046] Fig. 9 A schematic diagram of a method for ranging using a laser radar according to one aspect of the present invention is shown. DETAILED DESCRIPTION

[0047] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0051] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0052] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0053] The inventors of the present invention have found that the performance of high-beam laser radar will decline when measuring at close range, and the degree of decline of each beam is different; the laser spot of high-beam laser radar on nearby targets is seriously stacked, and the beams are redundant. Based on the above problems, when measuring close-range targets, a method of eliminating some beams can be designed based on the performance of each beam, so that the average performance of the remaining beams is as high as possible, and the distribution of the beams is as uniform as possible. The present invention proposes such a method.

[0054] Specifically, the inventor of the present application proposes a laser radar and a method for detecting using the laser radar. For example, when a target is identified to be in a certain close range, some redundant or poorly performing lines are intentionally shut down from the hardware or software, and these shut down lines may be the line bundles that intentionally sacrifice the close-range measurement performance in order to ensure the high performance of other lines in the close-range measurement during the design stage. Through this technology, not only does the recognition and detection capabilities of the target not decrease, but redundancy is reduced and detection accuracy is improved. The following is a detailed description with reference to the accompanying drawings.

[0055] Figure 1 A laser radar 100 according to the first aspect of the present invention is shown, which includes a transmitting unit 110, a receiving unit 120 and a processing unit 130. The transmitting unit 110 includes a laser or a laser array 111 (see FIG3 ), and the laser array 111 is configured to emit a plurality of laser beams L for target detection. The laser beam L is diffusely reflected by the target OB, and the reflected echo L′ returns to the laser radar and is received by the receiving unit 120. The receiving unit 120 includes a detector array 121 (see FIG4 ). Figure 3A ), the detector array 121 is configured to receive the echoes of the multiple laser beams reflected by the target and convert the echoes into electrical signals. The processing unit 130 is coupled to the receiving unit 120 to receive the electrical signals output by the detector array 121, and is configured to calculate the distance between the target and the laser radar according to the electrical signals output by the detector array 121. The processing unit 130 can, for example, determine the time of arrival of the echo according to the electrical signals output by the detector array, and calculate the flight time of the laser according to the emission time of the laser beam L, and then obtain the distance between the target and the laser radar based on the time of flight ranging method (TOF, distance = flight time * speed of light / 2). The processing unit 130 can be coupled to the transmitting unit 100, so that the emission time of the laser beam L can be known. Of course, it is also feasible to know the emission time by other means, which will not be repeated here. The processing unit 130 is also configured to output the electrical signals of some detectors in the detector array 121 according to a preset mode to form three-dimensional point cloud data when a preset condition is met. For example, preferably, when the target is identified to be in a certain close range, that is, when the distance between the target and the laser radar is less than a first preset value, the output of some redundant or poorly performing channels is turned off or discarded, thereby ensuring the high performance of the close-range measurement of other channels. This will be described in detail below.

[0056] Figure 2The figure shows the appearance of the laser radar 100. As shown in the figure, the laser radar 100 can emit multiple laser beams L in the vertical direction (the figure schematically shows 64 laser beams, L1, L2, ..., L63, L64, that is, a 64-line laser radar). The laser radar 100 has a rotating shaft 101, and the rotating shaft 101 is located inside the laser radar 100; the rotor of the laser radar 101 can rotate around the rotating shaft. The laser array 111 and the detector array 121 are usually located on the rotor and rotate around the rotating shaft 101.

[0057] Figure 3A Schematic diagram of the laser array 111 and the detector array 121 is shown. The laser array 111 includes a plurality of individually controllable lasers, such as A′ and B′, including edge-emitting lasers or vertical cavity surface-emitting lasers. The laser array 111 may be a laser array formed by a single laser or a linear array laser or a planar array laser. The detector array 121 is, for example, an array of detectors such as APD, SiPM, SPAD, etc. According to a preferred embodiment of the present invention, the laser array 111 and the detector array 121 are in a translation relationship relative to the rotation axis 101, such as Figure 3A As shown, of course, the laser array 111 and the detector array 121 can also be arranged symmetrically with respect to the rotating shaft 101. Usually, the laser and detector that match the long-distance field of view constitute a channel (or detection channel). When designing a multi-beam laser radar, the performance of long-distance measurement is generally given priority. The optical structure and electronic circuit design will try to make the radar achieve the highest efficiency at long distances. Ideally, the laser beam emitted by a laser, after diffuse reflection on a distant target, will irradiate the detector of the channel where the laser is located. The following description takes detection channel 1 and detection channel 2 as examples, where detection channel 1 includes laser A' and detector A, and detection channel 2 includes laser B' and detector B. For example, the echo generated by the laser beam emitted by laser A' after diffuse reflection from a distant target will ideally irradiate detector A; the echo generated by the laser beam emitted by laser B' after diffuse reflection from a distant target will ideally irradiate detector B. Figure 3A FIG. 1 shows that a plurality of lasers of the laser array 111 are arranged on a substrate. Figure 3B 2 shows a situation where multiple lasers are arranged on multiple substrates, wherein each laser is located at a different height in the vertical direction.

[0058] In addition, although Figure 3AThe laser array 111 included in the transmitting unit 110 is shown in the figure, but it is easy for those skilled in the art to understand that the transmitting unit 110 may also include a single laser instead of a laser array, and a scanning device, such as a one-dimensional swing mirror or a galvanometer, is arranged in the light emitting direction of the laser to scan the laser beam emitted by the single laser. When the scanning device is at different angles, the angles of the emitted laser beam are also different, so multiple laser beams L can also be formed for target detection. All of these are within the protection scope of the present invention.

[0059] Figure 3C The arrangement of the laser array 111 and the detector array 121 according to another embodiment of the present invention is shown. The detector array 121 includes a plurality of detectors, which are arranged in a row parallel to the direction of the rotating shaft 101, and the arrangement density of the detectors in the middle position of the row is higher than the arrangement density at the edge position of the row, that is, at the middle position, the spacing between the detectors is smaller; at the edge position, the spacing between the detectors is larger. In addition, the laser array 111 can also be arranged similarly, with a plurality of lasers arranged in a row parallel to the direction of the rotating shaft 101, and the arrangement density of the lasers in the middle position of the row is higher than the arrangement density at the edge position of the row. Such an arrangement of lasers and / or detectors is particularly preferred in some cases. For example, during the detection process, the laser radar often needs to have a higher resolution at the middle position of the field of view, so that the target object can be detected more accurately. Figure 3C In a preferred embodiment, by arranging the laser array 111 and the detector array more densely in the middle position and appropriately sparsely at the edge position, the detection performance of the laser radar can be effectively improved. Those skilled in the art should understand that arranging the lasers and / or detectors in multiple columns can further improve the spatial resolution.

[0060] According to one embodiment of the present invention, the transmitting unit 110 further includes a transmitting lens 112 (not shown), which is located downstream of the optical path of the laser array 111 and receives the multiple laser beams L, modulates the incident laser beam L and transmits it to the outside of the laser radar 100. The laser array 111 is located on the focal plane of the transmitting lens 112, so that the light beam emitted from the transmitting lens 112 is collimated into a parallel light beam. The receiving unit 120 further includes a receiving lens 122, which is configured to converge the echoes L′ of the multiple laser beams L reflected by the target object OB onto the detector array 121, and the detector array 121 is located on the focal plane of the receiving lens 122. Figure 3A As shown, the detector array 121 includes multiple columns of detectors along a first direction perpendicular to the rotation axis, Figure 3A Four columns are schematically shown in FIG. 1 , each column includes at least one detector distributed parallel to the rotation axis. Those skilled in the art should understand that the multiple columns of detectors in this embodiment are at least two columns of detectors.

[0061] According to a preferred embodiment of the present invention, when the target object is identified to be in a certain close range, for example, the distance from the laser radar is within 5 meters, then for the two or two columns of detectors where optical crosstalk may occur, the electrical signals of those detectors that are farther away from the rotating axis are preferentially turned off or discarded, and the electrical signals of those detectors that are closer to the rotating axis are output. Therefore, the preset mode includes: when the distance between the target object and the laser radar 100 is less than the first preset value, in the multiple columns of detectors shown in FIG3, for the two columns of detectors in the first direction where optical crosstalk may occur, the electrical signals of the column of detectors with a smaller distance from the rotating axis are output. The present invention is not limited to the specific numerical value of the first preset value, which can be determined based on specific parameter factors such as the number of lines of the laser radar 100, the arrangement of lasers, and the arrangement of detectors.

[0062] The inventors of the present invention have found that optical crosstalk is unidirectional. For non-coaxial optical systems, when the reflected echo from a nearby target reaches the detector array, the light spot is only biased in one direction. Therefore, the crosstalk attack is generally unidirectional, which is manifested as the crosstalk attack of the near-axis channel to the far-axis channel, such as Figure 4 As shown. Combined Figure 4 For comparison, to fully understand the embodiments of the present invention. Figure 4 As shown, when the laser radar 100 is used to detect a distant target, after the detection beam emitted by the laser A′ is reflected by the distant target, the radar echo is close to parallel light and will irradiate the detector A in the detection channel 1 where the laser A′ is located, as shown in FIG. Figure 4 This is the ideal situation shown in the upper left of the figure. When the laser radar 100 is used to detect nearby targets, the detection beam emitted by the laser A′ is reflected by the nearby target, and the radar echo is a non-parallel beam. Due to the diffusion of the light spot, it will irradiate the detector B next to the detector A. The detector B (located on the focal plane of the receiving lens system, at a different height from the focal plane of the detector A) also receives part of the light and is interfered with. Figure 1 As shown in the lower left of the figure, the offset and dispersion of the light spot will cause crosstalk between the various channels of the LiDAR, affecting the ranging precision and accuracy of the LiDAR. Figure 4The detectors A and B in the image may have optical crosstalk, so the electrical signal of the detector B which is farther from the rotation axis 101 can be turned off, and the electrical signal of the detector A which is farther from the rotation axis can be output. Correspondingly, for the two columns of detectors where the detectors A and B are located, the electrical signal of the detector column where the detector A is located can be read and output, while the electrical signal of the detector column where the detector B is located can be turned off. Figure 4 It can be clearly seen from the schematic diagram of the light spot drift in the lower left center that the electrical signal output by detector B at this time cannot truly represent the detection result of detection channel 2 where detector B is located. Therefore, if the electrical signal output by detector B is used to calculate and generate the point cloud of the laser radar, there will be quite significant errors. In the embodiment of the present invention, by removing the electrical signal output by detector B, such errors are effectively avoided or reduced.

[0063] Therefore, the above embodiments of the present invention are based on the unidirectionality of optical crosstalk, that is, the closer to the rotation axis (that is, the smaller the horizontal distance between the center of the detector of the channel and the rotation axis), the smaller the crosstalk attack. Figure 4 In the example, the horizontal distance between the center of detector A and the rotating shaft is smaller than that between the center of detector B and the rotating shaft, and the crosstalk attack is smaller. Therefore, the wire bundle (channel) left at a close distance should be as close to the rotating shaft as possible. And preferably, in the design stage, the photoelectric isolation of the left wire bundle (channel) is optimized to make them have better performance at a close distance.

[0064] It is easy for those skilled in the art to understand that "turning off" the electrical signal in the present invention has a relatively broad meaning, which may include physically isolating the optical path of the detector, not reading the electrical signal output by the detector (the target object distance is known by other means), or reading the electrical signal output by the detector but not outputting it to form three-dimensional point cloud data. The latter is an easier way to implement.

[0065] In the above embodiment, the "beam reduction" operation is performed in a first direction perpendicular to the rotation axis of the laser radar. Additionally or alternatively, the "beam reduction" operation may also be performed in a direction parallel to the rotation axis of the laser radar. This is described in detail below. According to one embodiment of the present invention, the preset mode includes: when the distance between the target object and the laser radar is less than the first preset value, the processing unit outputs an electrical signal of one detector for every n detectors in the direction parallel to the rotation axis of the detector array, where n is a positive integer. Figure 5 and Figure 6 The schematic diagrams of the laser scanning traces of distant targets and nearby targets are shown respectively. Figure 5As shown in the figure, when detecting distant targets, due to the long distance, the tracks scanned on the target can be clearly spaced apart, without spot stacking and redundancy, and all channels and maximum performance of the LiDAR can be maximized. Figure 6 As shown, when detecting nearby targets, the radiation divergence distance is short, so there is overlap and redundancy in the tracks or spots scanned by each laser beam on the target, which will affect the measurement accuracy of the lidar.

[0066] Figure 7 The comparison between the case of line reduction and the case of non-line reduction for a nearby target is shown. It can be seen that appropriate line reduction does not reduce the recognition and detection capabilities of the target, but reduces redundancy and improves detection accuracy. When designing the rules for close-range line reduction, it is necessary to design the distance range of the line reduction and the distribution of the reduced line bundles. Generally speaking, the distribution of the line bundles after line reduction should be ensured to be as uniform as possible, for example: leave one line every n lines (n is an integer).

[0067] In addition, according to a preferred embodiment of the present invention, the n can be a dynamically changing value, for example, as the distance between the target and the laser radar decreases, the value of n increases. The value of n should take into account the stacking of the beam spot, and n is determined according to the degree of stacking. One way is to select different n at different distances, for example: when entering the close-range line reduction range, first take n=1 and reduce the beam by half; when the distance continues to decrease, the spot stacking degree further increases, at this time n can be increased to 3, leaving 1 / 4 of the beam, and so on.

[0068] The above describes the embodiments of reducing the line in the first direction alone and reducing the line in the direction parallel to the rotation axis. It is easy for those skilled in the art to understand that in addition to reducing the line in the first direction alone and reducing the line in the direction parallel to the rotation axis, the two can also be combined, that is, reducing the line in the first direction and reducing the line in the direction parallel to the rotation axis at the same time, which are all within the scope of protection of the present invention and will not be repeated here.

[0069] According to a preferred embodiment of the present invention, the processing unit is configured to output the electrical signals of some detectors in the detector array according to the preset mode when the laser radar is within the preset vertical field of view. Figure 2 As shown, the laser radar 100 emits 64 laser beams in the vertical direction, corresponding to different vertical field of view angle ranges. According to actual conditions, the detection channel within a certain vertical field of view can be reduced.

[0070] A second aspect of the present invention relates to a method 200 for measuring distance using a laser radar, wherein the laser radar comprises a transmitting unit and a receiving unit, wherein the transmitting unit is Figure 1The transmitting unit 110 shown in FIG. 3 includes a laser array 111 (as shown in FIG. 3 ), and the receiving unit 110 includes a laser array 111 (as shown in FIG. 3 ). Figure 1 The receiving unit 120 shown in FIG. 3 includes a detector array 121 (as shown in FIG. 3 ). The method 200 is performed, for example, by Figure 1 The laser radar 100 shown is implemented. The distance measurement method 200 includes:

[0071] In step S201: a laser beam is emitted to the outside of the laser radar for target detection.

[0072] In step S202: receiving the echo of the laser beam reflected by the target object and converting the echo into an electrical signal.

[0073] In step S203: the distance between the target object and the laser radar is calculated according to the electrical signal output by the detector array.

[0074] In step S204: when a preset condition is met, the electrical signals of some detectors in the detector array are output according to a preset mode to form three-dimensional point cloud data.

[0075] According to a preferred embodiment of the present invention, the preset conditions include: the distance between the target object and the laser radar is less than a first preset value, the laser radar also includes a rotation axis 101, and the rotation axis is located inside the laser radar, wherein the detector array includes a plurality of columns along a first direction perpendicular to the rotation axis, and each column includes at least one detector distributed parallel to the rotation axis direction.

[0076] The step of outputting the electrical signals of some detectors in the detector array according to a preset mode to form three-dimensional point cloud data when the preset conditions are met includes:

[0077] For the two columns of detectors that may cause optical crosstalk in the first direction, the electrical signal of the column of detectors that is at a smaller distance from the rotation axis is output to form three-dimensional point cloud data.

[0078] According to a preferred embodiment of the present invention, the preset conditions include: the distance between the target object and the laser radar is less than a first preset value, the detector array includes a plurality of detectors, and the plurality of detectors are arranged in a row parallel to the rotation axis direction, wherein the arrangement density of the detectors at the middle position of the row is higher than the arrangement density at the edge position of the row, such as Figure 3C shown.

[0079] According to a preferred embodiment of the present invention, when a preset condition is met, the step of outputting electrical signals of some detectors in the detector array according to a preset mode to form three-dimensional point cloud data includes:

[0080] When the distance between the target object and the laser radar is less than the first preset value, every n detectors output an electrical signal in a direction parallel to the rotation axis to form three-dimensional point cloud data, where n is a positive integer.

[0081] According to a preferred embodiment of the present invention, as the distance between the target object and the laser radar decreases, the value of n increases.

[0082] According to a preferred embodiment of the present invention, when a preset condition is met, the step of outputting electrical signals of some detectors in the array of detectors according to a preset mode to form three-dimensional point cloud data includes:

[0083] When the laser radar is within a preset vertical field of view, electrical signals of some detectors in the detector array are output according to the preset mode to form three-dimensional point cloud data.

[0084] According to a preferred embodiment of the present invention, when generating three-dimensional point cloud data of a laser radar, the output of the detector is selected for generating three-dimensional point cloud data according to the distance between the target object and the laser radar. For example, when the distance between the target object and the laser radar is within 5 meters, the electrical signals of some of the detectors are selected for generating three-dimensional point cloud data, such as the electrical signals of the detectors close to the rotating shaft described above, or the electrical signals of the detectors left after a certain line reduction rule, or a combination of the two; and when the distance between the target object and the laser radar is greater than 5 meters, the electrical signals output by all detectors of the laser radar are selected for generating three-dimensional point cloud data. It is easy for those skilled in the art to understand that the above-mentioned distance of 5 meters is only an example, and those skilled in the art can set different distance values ​​according to actual conditions.

[0085] The present invention utilizes the characteristic of high-beam laser radar that the number of lines is redundant at close range. When designing the radar, priority is given to ensuring the close-range measurement performance of part of the beam, and the close-range performance of the other part of the beam is sacrificed as necessary. If the distance value measured by these beams with poor close-range performance is within a certain range at close range, the measurement results of these beams are not output. If the beam distribution of the laser radar is uneven, for example, it is encrypted within a certain vertical field of view angle range, and other vertical field of view angle ranges are non-encrypted, different line reduction rules can be formulated for beams in different vertical field of view angle intervals. By comparing the line reduction of nearby targets with that without line reduction, it can be seen that appropriate line reduction not only does not reduce the recognition and detection capabilities of the target, but reduces the redundancy of the beam and improves the detection accuracy.

[0086] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser radar, comprising: The transmitting unit includes a laser configured to emit a plurality of laser beams for target detection; A receiving unit, comprising a detector array, configured to receive echoes of the plurality of laser beams reflected by a target object and convert the echoes into electrical signals; A processing unit, configured to calculate the distance between the target object and the laser radar according to the electrical signals output by the detector array, and configured to output the electrical signals of some detectors in the detector array according to a preset mode when a preset condition is met; The preset conditions include: the distance between the target object and the laser radar is less than a first preset value; the laser radar also includes a rotation axis, and the preset mode includes: outputting electrical signals of some detectors in the detector array in a direction perpendicular to and / or parallel to the rotation axis.

2. The laser radar as claimed in claim 1, wherein the rotation axis is located inside the laser radar; The transmitting unit further comprises a transmitting lens, which is located downstream of the optical path of the laser and receives the multiple laser beams, modulates them and transmits them to the outside of the laser radar, and the laser array is located at the focal plane of the transmitting lens; The receiving unit further includes a receiving lens configured to converge the echoes of the multiple laser beams reflected by the target object onto the detector array, and the detector array is located at a focal plane of the receiving lens.

3. The laser radar according to claim 2, wherein the detector array comprises a plurality of columns along a first direction perpendicular to the rotation axis, each column comprises at least one detector distributed parallel to the rotation axis, and the preset mode comprises: When the distance between the target object and the laser radar is less than the first preset value, for the two columns of detectors that may cause optical crosstalk in the first direction, the electrical signal of the column of detectors that is at a smaller distance from the rotation axis is output.

4. The laser radar as described in claim 2, wherein the detector array includes a plurality of detectors, and the plurality of detectors are arranged in a row parallel to the rotation axis direction.

5. The laser radar according to any one of claims 2 to 4, wherein the preset mode comprises: When the distance between the target object and the laser radar is less than the first preset value, the processing unit outputs an electrical signal of every n detectors in the detector array in a direction parallel to the rotation axis, where n is a positive integer.

6. The laser radar according to claim 5, wherein the preset mode comprises: When the distance between the target object and the laser radar is less than the first preset value, the processing unit outputs the electrical signals of some detectors in the detector array in the following manner: as the distance between the target object and the laser radar decreases, the value of n increases.

7. A laser radar as described in claim 1 or 2, wherein the processing unit is configured to output the electrical signals of some detectors in the detector array according to the preset mode when the laser radar is within a preset vertical field of view.

8. The laser radar as described in any one of claims 1-3, wherein the transmitting unit includes a laser array formed by a single laser or a linear array laser or a planar array laser, and the laser includes an edge-emitting laser or a vertical cavity surface-emitting laser.

9. A method for measuring distance using a laser radar, wherein the laser radar comprises a transmitting unit and a receiving unit, wherein the transmitting unit comprises a laser, and the receiving unit comprises a detector array, wherein the method comprises: Emitting a laser beam to the outside of the laser radar for target detection; receiving an echo of the laser beam reflected by a target object and converting the echo into an electrical signal; Calculating the distance between the target object and the laser radar according to the electrical signal output by the detector array; When a preset condition is met, the electrical signals of some detectors in the detector array are output according to a preset mode to form three-dimensional point cloud data; The preset conditions include: the distance between the target object and the laser radar is less than a first preset value; the laser radar also includes a rotation axis, and the preset mode includes: outputting electrical signals of some detectors in the detector array in a direction perpendicular to and / or parallel to the rotation axis.

10. The method of claim 9, wherein the rotation axis is located inside the laser radar, wherein the detector array comprises a plurality of columns along a first direction perpendicular to the rotation axis, each column comprising at least one detector distributed parallel to the rotation axis, The step of outputting the electrical signals of some detectors in the detector array according to a preset mode to form three-dimensional point cloud data when the preset conditions are met includes: For the two columns of detectors that may cause optical crosstalk in the first direction, the electrical signal of the column of detectors that is at a smaller distance from the rotation axis is output to form three-dimensional point cloud data.

11. The method according to claim 10, wherein the preset condition comprises: The distance between the target object and the laser radar is less than a first preset value, and the detector array includes a plurality of detectors, and the plurality of detectors are arranged in a row parallel to the rotation axis.

12. The method according to claim 10 or 11, wherein when a preset condition is met, the step of outputting the electrical signals of some detectors in the detector array according to a preset mode to form three-dimensional point cloud data comprises: When the distance between the target object and the laser radar is less than the first preset value, every n detectors output an electrical signal in a direction parallel to the rotation axis to form three-dimensional point cloud data, where n is a positive integer.

13. The method of claim 12, wherein the value of n is increased as the distance between the target object and the laser radar decreases.

14. The method according to claim 13, wherein when a preset condition is met, the step of outputting the electrical signals of some detectors in the array of detectors according to a preset mode to form three-dimensional point cloud data comprises: When the laser radar is within a preset vertical field of view, electrical signals of some detectors in the detector array are output according to the preset mode to form three-dimensional point cloud data.

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