Point cloud scanning method of laser radar and laser radar

Abstract

The invention discloses a point cloud scanning method of a laser radar and the laser radar. The point cloud scanning method of the laser radar comprises the steps that light deflection angles corresponding to position areas with different point cloud angular resolutions in a view field area of the laser radar are acquired, and different light deflection angles correspond to different driving voltages; and applying the driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning. According to the invention, different position areas in the field of view of the laser radar correspond to different point cloud angular resolutions based on the liquid crystal phased array light, the time for scanning the whole frame of image in the field of view is saved, and the image frame rate of the laser point cloud is improved. Moreover, as the liquid crystal phased array can freely control the deflection angle of the light, the point cloud angular resolution in the view field area is adjusted through the liquid crystal phased array, and the point cloud performance of the laser point cloud cannot be affected.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic information technology, and in particular to a point cloud scanning method for lidar and a lidar. Background Technology

[0002] Light Detection and Ranging (LiDAR), as an emerging technology, is being used more and more widely in fields such as autonomous driving, intelligent robots, and surveying. The working principle of LiDAR is to emit a laser beam through a transmitting module and receive the laser beam reflected back from the target object through a receiving module. The receiving module converts the optical signal of the echo beam into an electrical signal, and after signal processing, three-dimensional point cloud data can be obtained.

[0003] The scanning device of a lidar system is a key component for acquiring 3D point cloud data. It enables the deflection of the laser beam in space. Currently, lidar scanning devices primarily employ semi-solid-state scanning devices such as rotating mirrors, tilting mirrors, or galvanometers. These semi-solid-state scanning devices control the direction of the laser beam through mechanical movement to achieve the scanning function. Their scanning time is related to the total field of view (FoV), and the scanning speed is fixed at various angles, making it difficult to modify and lacking flexibility.

[0004] Besides the aforementioned semi-solid-state scanning devices, optical phased arrays (OPA) can also be used. An OPA is a laser radar scanning method based on optical phased array technology. It achieves laser beam deflection by controlling the phase difference of multiple emitting units. Among them, the Liquid Crystal Optical Phased Array (LCOPA), also known as a liquid crystal phased array, is a very practical optical phased array. The light deflection principle of a liquid crystal phased array is based on electrically controlled birefringence and wavefront phase modulation technology. It achieves flexible adjustment of the beam direction by precisely controlling the alignment of liquid crystal molecules. This is because liquid crystal molecules have optical anisotropy; their refractive index changes with molecular orientation. When no electric field is applied, the liquid crystal molecules are uniformly aligned along the alignment layer. At this time, the refractive index of light passing through the liquid crystal layer is the ordinary refractive index (no). However, when a voltage is applied to the electrodes, the liquid crystal molecules rotate under the influence of the electric field, and their long axis gradually becomes parallel to the direction of the electric field. At this time, the refractive index of light becomes the extraordinary refractive index (ne). This birefringence effect causes a change in the optical path difference, thus producing a phase delay. Liquid crystal phased arrays can be classified into reflective liquid crystal phased arrays and transmissive liquid crystal phased arrays according to their operating mode. (Refer to...) Figure 1As shown, taking a vertically transmitted liquid crystal phased array as an example, it includes a liquid crystal layer and two electrodes encased in glass on the upper and lower sides of the liquid crystal layer. The upper electrode is a common electrode covering the entire surface, typically made of indium tin oxide (ITO). The lower electrode consists of multiple discrete electrodes, modulating the liquid crystal in each region. By applying different voltage values ​​to the two electrodes, the rotation degree of the liquid crystal molecules in each region differs, resulting in a corresponding change in the refractive index of light. When a laser beam (incident beam) is incident perpendicularly onto the liquid crystal phased array, it is split into multiple unit beams, each corresponding to a liquid crystal unit. A driving voltage is applied to the electrode corresponding to each liquid crystal unit, and the liquid crystal unit corresponding to each electrode generates a specific phase delay through voltage-phase conversion. According to the Huygens-Fresnel principle, each point on the wavefront can be considered a new wavelet source, and wavelet interference forms a new wavefront. By controlling the phase difference (Δϕ) between adjacent liquid crystal cells, a phase ramp is formed. The phase difference of the unit beam causes the synthesized wavefront to tilt, thereby changing the propagation direction of the laser beam and achieving the deflection of the laser beam, i.e., obtaining a deflected beam. The light deflection angle θs of the deflected beam is determined by the phase difference.

[0005] The switching time of the light deflection angle in a liquid crystal phased array is controlled by the thickness of the liquid crystal layer, the relaxation time of the liquid crystal molecules, and temperature. Based on their type and characteristics, liquid crystal phased arrays can be classified into nematic liquid crystal phased arrays, dual-frequency liquid crystal phased arrays, and ferroelectric liquid crystal phased arrays. Nematic liquid crystal phased arrays typically have switching speeds on the order of milliseconds, while dual-frequency and ferroelectric liquid crystal phased arrays can reach speeds on the order of hundreds of microseconds. Summary of the Invention

[0006] To increase the selection space of lidar point cloud scanning methods and improve the flexibility of lidar point cloud scanning, this invention provides a lidar point cloud scanning method and a lidar.

[0007] In a first aspect, embodiments of the present invention provide a point cloud scanning method for lidar, comprising: Obtain the light deflection angle corresponding to the position region of different point cloud angular resolutions within the field of view of the lidar, where different light deflection angles correspond to different driving voltages; The driving voltage corresponding to each light deflection angle is applied to the liquid crystal phased array for point cloud scanning.

[0008] Secondly, embodiments of the present invention provide a lidar, comprising: a plurality of liquid crystal phased arrays and a control module; The liquid crystal phased array is used to deflect the incident laser beam by a corresponding optical deflection angle according to the applied driving voltage. The control module is used to, for each liquid crystal phased array, obtain the light deflection angle corresponding to the position region of different point cloud angular resolutions within the field of view of the liquid crystal phased array, wherein different light deflection angles correspond to different driving voltages; and apply the driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning.

[0009] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following: The point cloud scanning method for lidar provided in this invention designs light deflection angles corresponding to different locations within the lidar's field of view based on the point cloud angular resolution requirements of different areas within the field of view. It also pre-determines the driving voltage corresponding to each light deflection angle. By continuously applying the driving voltage corresponding to each light deflection angle to the liquid crystal phased array, the beam deflection of the liquid crystal phased array is controlled to perform point cloud scanning, thus realizing the lidar's field of view scanning. By using liquid crystal phased array light to achieve different point cloud angular resolutions for different locations within the lidar's field of view, the time required to scan the entire frame of the field of view is saved, improving the image frame rate of the laser point cloud. Furthermore, since the liquid crystal phased array can control the light deflection angle relatively freely, adjusting the point cloud angular resolution in the field of view through the liquid crystal phased array will not affect the point cloud performance of the laser point cloud.

[0010] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0011] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0012] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram illustrating the working principle of a vertically transmitted liquid crystal phased array. Figure 2 This is a schematic diagram of the scanning field of view of a lidar. Figure 3 This is a schematic diagram of the scanning field of view of another type of lidar; Figure 4 This is a flowchart of the point cloud scanning method of the lidar in an embodiment of the present invention; Figure 5 This is a schematic diagram of the field of view distribution of a lidar that uses semi-fixed scanning devices and a liquid crystal phased array. Figure 6 This is a schematic diagram showing the angular-time relationship between a semi-fixed scanning device and a liquid crystal phased array. Figure 7 This is a schematic diagram of the field of view distribution of a lidar using a liquid crystal phased array in an embodiment of the present invention; Figure 8 This is a schematic diagram of the field-of-view scanning sequence of a lidar that uses semi-fixed scanning devices and a liquid crystal phased array; Figure 9 This is a schematic diagram of the transmitting optical path of a lidar based on a liquid crystal phased array in an embodiment of the present invention; Figure 10 This is a schematic diagram of the light source block for emitting pulsed light at the transmitting end and the corresponding pixel block and surrounding preset pixel block at the receiving end in an embodiment of the present invention. Figure 11 This is a schematic diagram illustrating the relative positional relationship between the transmitting end lens, the transmitting end, the receiving end lens, and the receiving end in an embodiment of the present invention. Figure 12 This is a schematic diagram illustrating the case where several pixel blocks to the right of RX_k are selected as the neighboring blocks in an embodiment of the present invention; Figure 13 A schematic diagram illustrating the relationship between the left and right boundaries of a preset time range and the position of a signal peak in a flight time mode one provided in an embodiment of the present invention; Figure 14 A schematic diagram illustrating the relationship between the left and right boundaries of the preset time range and the signal peak position in the second flight time mode provided in this embodiment of the invention; Figure 15 This is a schematic diagram illustrating the relationship between the left and right boundaries of the preset time range and the signal peak position in the second method for determining the position of the imaging spot provided in this embodiment of the invention. Figure 16 This is a schematic diagram illustrating an example of the spatial distribution of the sum of avalanche counts corresponding to each pixel in an embodiment of the present invention. Figure 17 The structural block diagram of the lidar provided in the embodiment of the present invention. Detailed Implementation

[0013] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0014] The inventors of this application have discovered that the requirements for the point cloud in the field of view vary depending on the specific application scenario of a lidar system. For example, referring to... Figure 2As shown, for vehicle-mounted forward-facing main LiDAR, the center field of view has a longer range, requiring a higher point cloud angular resolution, while the edges have shorter ranges, allowing for a lower point cloud angular resolution. For example, refer to... Figure 3 As shown, the angular resolution of the point cloud in the ground field of view of a lidar needs to be higher, while the angular resolution in the air field of view needs to be lower. The scanning time of semi-solid-state scanning devices such as rotating mirrors, tilting mirrors, or galvanometers is related to the total field of view (FoV). Since the scanning speed of semi-solid-state deflection devices is fixed, they can only achieve uniform light scanning along the horizontal field of view (H-FoV) and the vertical field of view (V-FoV). This method cannot save time and cannot improve the frame rate of the laser point cloud. Through extensive research, the inventors discovered that if the beam deflection principle of a liquid crystal phased array can be used, and the switching frequency of the liquid crystal phased array can be reduced accordingly based on the point cloud angular resolution requirements of different locations in the field of view for different lidar application scenarios, the point cloud angular resolution in some areas can be reduced, thereby saving the scanning time of the entire frame image of the scanning field of view and effectively improving the image frame rate of the laser point cloud. Based on this, this invention provides a point cloud scanning method and a lidar. The following is a detailed description through specific embodiments.

[0015] Reference Figure 4 As shown, this embodiment of the invention provides a point cloud scanning method for lidar, comprising the following steps: S11: Obtain the light deflection angle corresponding to the position region with different point cloud angular resolutions within the field of view of the lidar, where different light deflection angles correspond to different driving voltages.

[0016] S12: Apply the driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning.

[0017] The point cloud scanning method for lidar provided in this invention designs light deflection angles corresponding to different locations within the lidar's field of view based on the point cloud angular resolution requirements of different areas within the field of view. It also pre-determines the driving voltage corresponding to each light deflection angle. By continuously applying the driving voltage corresponding to each light deflection angle to the liquid crystal phased array, the beam deflection of the liquid crystal phased array is controlled to perform point cloud scanning, thus realizing the lidar's field of view scanning. By using liquid crystal phased array light to achieve different point cloud angular resolutions for different locations within the lidar's field of view, the time required to scan the entire frame of the field of view is saved, improving the image frame rate of the laser point cloud. Furthermore, since the liquid crystal phased array can control the light deflection angle relatively freely, adjusting the point cloud angular resolution in the field of view through the liquid crystal phased array will not affect the point cloud performance of the laser point cloud.

[0018] In step S11 above, the light deflection angle corresponding to the position area of ​​different point cloud angular resolutions within the field of view of the lidar can be pre-configured according to the different point cloud angular resolution requirements within the field of view. Based on the working principle of the liquid crystal phased array, the driving voltage corresponding to each light deflection angle can be obtained.

[0019] In step S12 above, based on the acquired light deflection angles and their corresponding driving voltages, the driving voltage corresponding to each light deflection angle is continuously applied to the liquid crystal phased array, thereby continuously controlling the beam deflection of the liquid crystal phased array, deflecting the laser beam to each light deflection angle, realizing the field-of-view scanning of the lidar, obtaining non-uniform laser point clouds, and meeting the point cloud requirements of lidar for different locations in the field of view.

[0020] To better understand the point cloud scanning method of the above-mentioned lidar and to demonstrate the beneficial effects of the embodiments of the present invention, the implementation methods of semi-solid-state scanning devices and liquid crystal phased arrays are compared and explained below through specific examples: For example, refer to Figure 5 As shown in Figure a, the rectangular frame represents the field of view of the lidar in object space, i.e., the field of view area. The circular spots in the figure represent the illumination of the emitted laser beam after deflection within the field of view (i.e., the positions of individual illumination points). The scanning time of semi-solid-state scanning devices such as rotating mirrors, tilting mirrors, or galvanometers is related to the total field of view (FoV). Because the scanning speed of the deflection device is fixed, semi-solid-state lidars can only achieve uniformly distributed light scanning along the horizontal field of view (H-FoV) and the vertical field of view (V-FoV), thus obtaining... Figure 5 The uniform laser point cloud shown in figure a. Using this method, the cycle for scanning the point cloud of the entire field of view is fixed, and it cannot save time to improve the frame rate of the laser point cloud. Also refer to... Figure 6 As shown in the figure, the blue lines represent the angle-time relationship of semi-solid-state scanning devices. Semi-solid-state scanning devices such as rotating mirrors, tilting mirrors, or galvanometers are continuous light deflections. The scanning time within the same angle range cannot be changed, and their minimum point cloud angular resolution is locked by the scanning speed. If you want to achieve a low point cloud angular resolution, you can only increase the time interval between adjacent point cloud distance measurements, which will affect the point cloud performance.

[0021] In this embodiment of the invention, the inventors propose that, based on the principle of beam deflection of a liquid crystal phased array, the point cloud angular resolution of different locations in the field of view can be adjusted accordingly for different application scenarios of lidar. That is, the number of switching times of the liquid crystal phased array can be reduced or increased accordingly in different locations in the field of view, thereby achieving the adjustment of the point cloud angular resolution of different locations in the field of view.

[0022] For example, refer to Figure 5 As shown in b, compared to Figure 5 a. Using a liquid crystal phased array for laser point cloud scanning reduces the angular resolution of the point cloud in some areas, which means reducing the number of times the liquid crystal phased array is switched, thereby saving the scanning time of the entire frame image of the scanning field of view and effectively improving the image frame rate of the laser point cloud.

[0023] Furthermore, liquid crystal phased arrays are discrete optical deflectors, continuing to refer to... Figure 6 As shown, the red lines represent the angle-time relationship of the liquid crystal phased array. Compared to the continuous light deflection of semi-solid-state scanning devices, where the scanning time within the same angle range cannot be changed, the angle held after light deflection in a liquid crystal phased array depends on the duration of the driving voltage applied to the array. The cycle for completing the full-frame image point cloud scan of the field of view is adjustable, meeting the point cloud requirements of the field of view for LiDAR in different application scenarios.

[0024] Also refer to Figure 7 As shown in Figure a, a liquid crystal phased array is used to change the point cloud angular resolution distribution in the central region, achieving a non-uniform distribution of point cloud angular resolution in the field of view. (Refer to...) Figure 7 As shown in b, the use of a liquid crystal phased array increases the point cloud angular resolution in the central region.

[0025] Depend on Figure 7 a and Figure 7 b combination Figure 4 As can be seen from b, the point cloud angular resolution in the field of view can be adjusted by using a liquid crystal phased array. This can not only reduce the point cloud angular resolution in some areas, but also increase the point cloud angular resolution in others. Compared with the semi-solid-state scanning device, which achieves low point cloud angular resolution by increasing the time interval between adjacent point cloud measurements, this method does not affect the point cloud performance of the laser point cloud.

[0026] Since the liquid crystal phased array uses discrete optical deflection, the optical deflection angles of two adjacent optical deflections can be discontinuous. The inventors propose that during lidar point cloud scanning, the point cloud being scanned can be controlled to spatially jump. Based on this, in step S12 above, the driving voltage corresponding to each optical deflection angle is applied to the liquid crystal phased array for point cloud scanning, which specifically includes the following steps: S121: Randomly sort the scanning order of position regions with different point cloud angular resolutions within the field of view to determine the arrangement order of all light deflection angles.

[0027] S122: According to the arrangement order of all light deflection angles, the driving voltage corresponding to each light deflection angle is applied to the liquid crystal phased array to perform point cloud scanning.

[0028] In this embodiment of the invention, in step S121 above, the position regions with different point cloud angular resolutions within the field of view can be numbered, and the numbering of the position regions with different point cloud angular resolutions within the field of view can be randomly sorted by a random sequence generator to obtain the arrangement order of the numbering of the position regions with different point cloud angular resolutions, that is, the arrangement order of each light deflection angle corresponding to the position regions with different point cloud angular resolutions, which is the arrangement order of all the light deflection angles mentioned above.

[0029] In this embodiment of the invention, when numbering the position regions of different point cloud angular resolutions within the field of view, the numbering can be done according to the rows or columns of the laser point cloud, or each illumination point of the laser point cloud can be numbered separately. The specific numbering method can be numerical, alphanumeric, or other methods, and is not specifically limited here.

[0030] In step 122 above, the driving voltage corresponding to each light deflection angle is applied to the liquid crystal phased array in sequence according to the arrangement order of all light deflection angles, so as to realize the continuous control of the beam deflection of the liquid crystal phased array and obtain a non-uniform laser point cloud.

[0031] For example, refer to Figure 8 As shown in Figure a, the semi-solid-state scanning device can only scan from left to right when performing point cloud scanning. However, in some other embodiments, it can also scan from right to left. In this embodiment of the invention, referring to... Figure 8 As shown in b, when the driving voltage corresponding to each optical deflection angle is applied to the liquid crystal phased array for point cloud scanning according to the arrangement order of all optical deflection angles, two adjacent optical deflection angles of the liquid crystal phased array can be discontinuous. Compared with the continuous scanning method of semi-solid-state scanning devices, the discontinuous scanning method in this embodiment of the invention can avoid interference from other radars in the same field of view and the same scanning order, which is equivalent to spatial encoding and transmission, reducing the impact of interference noise, helping to improve the signal-to-noise ratio of lidar ranging, and enhancing the quality of point cloud images.

[0032] In this embodiment of the invention, the time for maintaining the angle after light deflection in the liquid crystal phased array depends on the user configuration. Based on this, the above-mentioned point cloud scanning method for lidar may further include the following steps: Obtain the pre-configured angle hold time after optical deflection; When applying the driving voltage corresponding to each light deflection angle to the liquid crystal phased array, the applied voltage is maintained for the angle holding time after the light deflection.

[0033] In this embodiment of the invention, a liquid crystal phased array serves as a scanning device, positioned downstream of the emitting end in the laser radar's optical path. In this embodiment, the emitting end of the laser source serves as the light-emitting source and may comprise multiple light-emitting blocks. These blocks can be arranged in a two-dimensional array; for example, the emitting source may include M (number of columns) × N (number of rows) light source blocks, each containing multiple light-emitting units. It should be understood that in other embodiments, the multiple light source blocks may be arranged in other regular or irregular patterns, and this application does not limit this arrangement.

[0034] Optionally, the light-emitting unit can be, for example, a vertical-cavity surface-emitting laser (VCSEL). Alternatively, the emitting light source can also be an edge-emitting laser (EEL), a light-emitting diode (LED), a laser diode (LD), a fiber laser, or other similar light-emitting device. The edge-emitting laser can be a Fabry-Perot (FP) laser, a distributed feedback (DFB) laser, an electro-absorption modulated (EML) laser, etc., and this application does not limit the specific type of laser used.

[0035] In one embodiment, reference is made to Figure 9 As shown, a collimating lens and a polarizer can also be placed between the laser source and the liquid crystal phased array at the transmitting end. The laser beam emitted by the source is collimated and polarized before being incident on the liquid crystal phased array, and then deflected to a specified field of view. By continuously controlling the beam deflection of the liquid crystal phased array, the field of view scanning of the lidar can be achieved.

[0036] In this embodiment of the invention, the receiving end of the lidar includes multiple pixel blocks, each containing at least one pixel. The pixel blocks of the receiving end correspond to the light source blocks of the transmitting end; for example, the pixel blocks of the receiving end correspond one-to-one with the light source blocks of the transmitting end, or one pixel block of the receiving end corresponds to at least two light source blocks of the transmitting end.

[0037] In one specific embodiment, the receiver can be implemented, for example, using a single photon avalanche diode (SPAD) array chip. The receiver has a total of M×N pixel blocks, and each pixel block corresponds to a light source block of the emitting light source. In this way, the M×N pixel blocks of the receiver correspond one-to-one with the M×N light source blocks of the light source.

[0038] Based on the above-described configuration of the laser light source's transmitter and receiver, in this embodiment of the invention, the point cloud scanning method of the laser radar may further include the following steps: When a driving voltage is applied to the liquid crystal phased array, the control transmitter opens the light source block corresponding to the position of the liquid crystal phased array; Accordingly, when a driving voltage is applied to the liquid crystal phased array, the control receiver opens the pixel block of the induced echo beam corresponding to the position of the light source block, as well as each pixel block within a preset range around the pixel block of the induced echo beam. For each light deflection angle, the histogram information of the induced echo beams of each pixel in each pixel block that is opened is statistically analyzed. Based on the histogram information of each pixel, the position of the signal peak in the histogram information is determined; The avalanche count of each pixel within a preset time range before and after the position of the signal peak is counted. Based on the spatial distribution of the avalanche count of each pixel within the preset time range before and after the signal peak, the position of the imaging spot is determined. Determine whether the position of the imaging spot matches the position of the spot with the corresponding light deflection angle in the pre-stored spot image information; if not, send an alarm message for abnormal operation of the liquid crystal phased array.

[0039] In this embodiment of the invention, when the lidar emits a laser beam through light source blocks at the transmitting end and deflects it at each light deflection angle by the liquid crystal phased array, it can use the corresponding pixel blocks at the receiving end, as well as the induced echo beams corresponding to each pixel block within a preset range around the corresponding pixel block, to convert the histogram information obtained from the pixel induced echo beams contained in these pixel blocks into grayscale information corresponding to the pixels contained in these pixel blocks (characterized by avalanche counts within a preset time). This allows for accurate determination of the actual position of the imaging spot. The pre-stored spot image information is compared with the actual position of the imaging spot to determine whether the liquid crystal phased array is working properly. The spot position in the pre-stored spot image information represents the designed position of the spot corresponding to the light deflection angle. If the actual position of the imaging spot does not match the designed position, it indicates that the liquid crystal phased array is malfunctioning, and an alarm message for liquid crystal phased array malfunction is sent.

[0040] In this embodiment of the invention, a light deflection device, i.e., a scanning device at the receiving end, is further disposed on the echo optical path of the lidar before the receiving end. This light deflection device can be a semi-solid-state scanning device or an optical phased array, including a liquid crystal phased array. Based on this, the above-mentioned point cloud scanning method for lidar may further include the following steps: When a driving voltage is applied to the liquid crystal phased array, the light deflection devices corresponding to the pixel blocks of the sensed echo beam are controlled to deflect the echo beam by a corresponding light deflection angle, and, The light deflection devices corresponding to each pixel block within a preset range around the pixel block of the sensed echo beam are controlled to deflect the echo beam by a corresponding light deflection angle.

[0041] In this embodiment of the invention, if the location of the imaging spot matches the position of the spot corresponding to the light deflection angle in the pre-stored spot image information, the ranging of the lidar can be further achieved through the following steps: Calculate the offset between the location of the imaging spot and the pixel block corresponding to the light source block, and calculate the first distance of the target object based on the offset.

[0042] In this embodiment of the invention, when a driving voltage is applied to the liquid crystal phased array, the receiving end activates the pixel block corresponding to the position of the light source block that emits the current pulse light, as well as each pixel block within a preset range around that pixel block. (Refer to...) Figure 10 In the example shown, assuming the light source block TX_k emitting the pulsed light is located at the position shown by the red block in the left diagram, then the pixel block activated at the receiving end is located at the position shown by the green block on the right. The green block on the right includes both the pixel block RX_k corresponding to the position of the red block (i.e., the pixel block at the second row and third column, position (2,3)) and the pixel blocks within a preset range surrounding this pixel block. Figure 10 In the example shown, the enabled pixel blocks are RX_k itself and the surrounding 11 pixel blocks.

[0043] In one embodiment, the preset range is greater than or equal to the maximum offset of the imaging spot. If the preset range exceeds the boundary of the receiving end, the preset range ends at the boundary of the receiving end.

[0044] The aforementioned maximum offset is determined based on the range of the lidar triangulation ranging method.

[0045] To make it easier to understand, the principle of trigonometric distance measurement is briefly introduced below.

[0046] Reference Figure 11As shown, the position of the imaging spot when the baseline (B) between the transmitting end's TX lens and the receiving end's RX lens is not zero is A, and the position of the imaging spot when the baseline between the TX and RX lenses is zero is A0. Clearly, the baseline between the lenses causes a shift in the position of the imaging spot. According to the properties of similar triangles, the shift in the imaging spot position can be expressed as Δu = k1 ×B / z, where k1 is the distance between the optical centers of the receiving end and the RX lens, and z is the vertical distance between the target object and the radar. Therefore, by measuring the shift in the imaging spot position, the distance to the object can be further obtained.

[0047] 1. When z is much larger than B, Δu is approximately zero, making it impossible to accurately measure the value of Δu. This results in a very large error in the distance value obtained, rendering the distance measurement invalid.

[0048] 2. When z approaches zero, Δu tends to infinity, exceeding the measurement range and rendering the distance measurement invalid.

[0049] Therefore, the measurement range of the triangulation method is limited and definite, determined by parameters k1 and B. Once parameters k1 and B are determined, the measurement range is fixed, and the range of values ​​for the spot offset is also fixed.

[0050] Differentiating both sides of the distance expression, we obtain the expression for the distance resolution: dz = -(z) 2 / (k1 ×B))× d(Δu). Obviously, the ranging resolution of the trigonometric method is proportional to the square of the distance; the larger the distance, the worse the resolution. Excellent distance resolution can be obtained at close range.

[0051] In one embodiment, the selection principle for pixel blocks (hereinafter referred to as neighboring blocks) within a preset range around RX_k may further refer to the following principles: If the transmitting lens and the receiving lens are arranged along the baseline, then each pixel block within the preset range is a number of pixel blocks arranged sequentially on the baseline in a direction away from the transmitting lens, corresponding to the position of the light source block of the currently emitted pulse light.

[0052] Once the relative positions of the TX and RX lenses are determined, the direction of the light spot movement on the image plane due to parallax is also determined. If the TX and RX lenses are arranged horizontally, with a non-zero baseline in the horizontal direction and a zero baseline in the vertical direction, then the light spot movement on the image plane will primarily be along the horizontal direction; that is, the horizontal offset will be much greater than the vertical offset. If the RX lens is to the right (left) of the TX lens, then the light spot on the image plane will definitely move to the right (left). A similar conclusion applies if the TX and RX lenses are arranged vertically, and will not be elaborated further.

[0053] In this embodiment, it is assumed that the TX lens and RX lens are arranged horizontally and the RX lens is to the right of the TX lens (if the RX lens is to the left of the TX lens, the chip only needs to be rotated 180°; if the TX lens is arranged vertically, the chip only needs to be rotated 90°). Since the light spot movement is mainly along the horizontal direction and always moves to the right, the neighboring blocks of RX_k can be selected from several pixel blocks to its right.

[0054] In the aforementioned embodiments, although the imaging spot mainly moves horizontally, there may also be a certain offset in the vertical direction. If a single pixel block contains few pixels in the vertical direction, such as a single pixel block containing only one pixel, the spot will move out of the current row, resulting in the selected RX_k and its neighboring blocks not receiving the spot. Therefore, this solution is suitable for situations where a single pixel block contains a large number of pixels in the vertical direction.

[0055] Reference Figure 12 As shown, the left side shows the light source block TX_k (represented by red blocks) of the emitted light pulse at the transmitting end, and the right side shows the pixel block RX_k (represented by dark green) corresponding to the light source block at the receiving end, as well as the neighboring pixel blocks of RX_k. These neighboring pixel blocks are several pixel blocks to the right of RX_k (represented by light green).

[0056] When the RX lens is to the left of the TX lens, it can be compared with... Figure 12 The situation shown is the opposite, with neighboring pixel blocks being several pixel blocks to the left of RX_k.

[0057] In one embodiment, the above method may further perform the following steps: obtaining the time of flight based on the histogram information of pixels in the pixel block corresponding to the current light source block position of the emitted pulse light, and calculating the second distance of the target object based on the time of flight.

[0058] The specific implementation of the above steps for calculating the second distance of the target object based on the time of flight can be found in the dToF method. The time of flight is determined by using the histogram information of the pixels in the pixel block corresponding to the position of the light source block that emits the pulse light. Then, the distance between the lidar and the target object is calculated using the formula d=c×t / 2 (where t is the time of flight and c is the speed of light).

[0059] The following is combined Figure 11 This provides a brief explanation of the TOF ranging principle, referring to... Figure 11As shown, the path a photon travels from emission to reception is S = z / cosβ + f / cosβ + z / cosθ + k1 / cosθ, where, Figure 11 In the diagram, the angle between the optical axis of the transmitting end's TX lens and the emitted light beam is β (the angle between the optical axis of the receiving end's RX lens and the incident light beam is also β). This angle β is determined by the photon emission position and the TX lens parameters. θ is determined by the position of the imaging spot and the RX lens parameters. f is the distance between the light source and the optical center of the TX lens, k1 is the distance between the receiving end and the optical center of the RX lens, and z is the perpendicular distance between the object and the radar. Assuming the photon's flight time from emission to reception is t, then S = c × t, where c is the speed of light.

[0060] Combining the above two equations, we can obtain z × (1 / cosβ + 1 / cos θ) + f / cosβ + k1 / cos θ = c×t. Therefore, by measuring the flight time of the photon, we can further obtain the distance to the object.

[0061] When z is much larger than B, θ ≈ β, f / cosβ + k1 / cos θ is a small quantity and can be ignored, z = cosθ × c × t / 2.

[0062] The ranging range of dTOF is determined by the range of the timer.

[0063] Differentiating both sides of the distance expression, we obtain the expression for the distance resolution: (1 / cosβ + 1 / cos θ) × dz = c × dt. The distance resolution of dTOF is proportional to the time resolution, and remains constant throughout the entire measurement range.

[0064] In this embodiment of the invention, for the sole purpose of distinction, the distance between the offset between the imaging spot and the pixel block corresponding to the light source block, calculated using the triangulation method, is called the first distance, while the distance calculated using the flight time determined by the time-of-flight method based on the histogram is called the second distance.

[0065] In one embodiment, after calculating the first distance and the second distance, the method may further perform the following steps: The first distance and the second distance are compared with a preset distance threshold. Based on the comparison result, the first distance or the second distance is selected for output.

[0066] Furthermore, in one embodiment, if it is determined that the second distance is greater than a preset distance threshold, the second distance is selected for output; otherwise, the first distance is selected for output.

[0067] In some scenarios, the distance between the LiDAR and the target object is relatively far. In this case, the second distance is more accurate than the first distance, so the second distance can be selected for output. Conversely, when the distance between the LiDAR and the target object is relatively close, the first distance is more accurate than the second distance, so the first distance can be selected for output.

[0068] Optionally, the first distance and the second distance can be output simultaneously for further analysis using other strategies to obtain the final result. For example, the final output value can be obtained by comprehensively considering the first distance and the second distance. This embodiment of the invention does not limit how the final ranging result is output based on the first distance and the second distance.

[0069] In this embodiment of the invention, after the final output value information of each illumination point is recorded, it can be further processed, such as filtering, denoising, and point cloud registration. The processed data is used to generate a laser point cloud. A laser point cloud is a set of points in three-dimensional space, where each point represents a point on the surface of a target object detected by the lidar.

[0070] In one embodiment, the step of obtaining the time of flight based on the histogram information of pixels in the pixel block corresponding to the determined light source block position of the currently emitted pulse light can be implemented in one of the following two ways: Method 1 for obtaining flight time: 5.1. Reference Figure 13 As shown, the peak position P of the signal peak is determined by searching the histogram information of the pixels in the pixel block corresponding to the current light source block position of the emitted pulse light. 5.2 Determine the two positions of the first left boundary PL1 and the first right boundary PH1 within the preset time range before and after the position of the signal peak; where: PL1 = PW / 2, PH1 = P + W / 2; W is the pulse width of the pulse light sent by the light source in blocks; 5.3 Calculate the centroid of the flight time axis in the histogram within the range [PL1, PH1] to determine the centroid position Pc; For example, the centroid can be calculated using the following formula: (h1×t1+h2×t2+…hn×tn) / (h1+h2+…hn), where h1, h2…hn represent the histogram counts corresponding to each time bin within the range [PL1, PH1], and t1, t2…tn represent the time of each time bin within the range [PL1, PH1].

[0071] 5.4. The time to obtain the Pc position is taken as the photon's flight time.

[0072] Using time-of-flight ranging, only the histogram information of the pixel blocks (i.e., the aforementioned RX_k blocks) corresponding to the light source blocks that emit pulsed light is considered.

[0073] To ensure the accuracy of the time-of-flight ranging results, the determination of the flight time also needs to be precise. Therefore, in the above scheme, the peak is first roughly found, and then the centroid is calculated to finally determine the accurate "peak" of the histogram, thereby improving the accuracy of the flight time calculation.

[0074] In one embodiment, if the calculated PL1 or PH1 is a decimal, a rounding operation needs to be performed, for example, as follows: If the calculated value of PL1 is a decimal, then the largest integer smaller than it is taken as the value of PL1; If the calculated value of PH1 is a decimal, then the smallest integer greater than it is taken as the value of PL1; If the calculated PL1 exceeds the left boundary of the histogram, then the position of the left boundary is taken as the value of PL1; If the calculated PH1 exceeds the right boundary of the histogram, then the position of the right boundary is taken as the value of PH1.

[0075] Method 2 for obtaining flight time: 6.1. Reference Figure 14 As shown, peak finding is performed on the histogram information of pixels in the pixel block corresponding to the current emitted pulse light source block position to determine the position P of the signal peak and the avalanche count Γ of the signal peak position P. 6.2. Move to the left from the position of the signal peak to find the position where the first avalanche count is γ times Γ; determine the time of the first avalanche count being γ times Γ as the photon's flight time; where γ∈(0, 1); In one embodiment, the value of γ can be, for example, 0.1, 0.3, 0.5, or 0.7.

[0076] In both methods 1 and 2, if no signal peak is found in the histogram information of the pixels in the pixel block corresponding to the current position of the light source block that emits the pulse light, the flight time can be directly determined to be 0.

[0077] In this embodiment of the invention, a pixel block may contain one pixel or multiple pixels (i.e., the number of pixels is greater than 1).

[0078] In one embodiment, the steps described above—determining the position of the signal peak in the histogram information based on the histogram information of each pixel; calculating the sum of avalanche counts within a preset time range before and after the position of the signal peak for each pixel; and determining the location of the imaging spot based on the spatial distribution of the sum of avalanche counts within the preset time range before and after the signal peak for each pixel—can be implemented in the following two ways: Method 1 for determining the position of the imaging spot: 7.1. Peak finding is performed on the histogram information of the pixel block corresponding to the current light source block position of the emitted pulse light and the pixels in each pixel block within a preset range around the pixel block; Depending on whether a peak can be found in the pixel being searched, the process is divided into two cases, as described in 7.2 and 7.3: 7.2 If no peak is found, the sum of the avalanche counts corresponding to that pixel is 0; 7.3 If a peak can be found, determine the position P of the signal peak for that pixel; and determine the positions of the second left boundary PL2 and the second right boundary PH2 within a preset time range before and after the position P of the signal peak; where: PL2 = PW / 2, PH2 = P + W / 2 (refer to...) Figure 13 (As shown); W is the pulse width of the pulsed light transmitted by the light source in blocks; Optionally, if the values ​​of PL2 and PH2 are decimals, they can be rounded down.

[0079] For example, if the calculated value of PL2 is a decimal, then the largest integer smaller than it is taken as the value of PL2; if the calculated value of PH2 is a decimal, then the smallest integer larger than it is taken as the value of PL2. If the calculated PL2 exceeds the left boundary of the histogram, then the position of the left boundary is taken as the value of PL2; If the calculated PH2 exceeds the right boundary of the histogram, then the position of the right boundary is taken as the value of PH2.

[0080] 7.4 For pixels where a peak can be found, the sum of all avalanche counts within the range [PL2, PH2] in the histogram is taken as the total avalanche count for that pixel; 7.5 Determine the location of the imaging spot based on the spatial distribution of the pixel block corresponding to the current emitted pulse light source block position and the sum of the avalanche counts of each pixel in each pixel block within a preset range around the pixel block.

[0081] After the processing in steps 7.1-7.4 above, for the pixel block corresponding to the current light source block position of the emitted pulse light, and for each pixel block within a preset range around the pixel block, the avalanche count sum is 0 for some pixels that cannot find a peak, and a non-zero integer for pixels that can find a peak. In step 7.5, by combining the positional distribution of these pixels and their individual avalanche counts, the spatial distribution of the total avalanche count of each pixel can be determined. Then, based on the spatial distribution of the total avalanche count of each pixel, the location of the imaging spot can be determined.

[0082] For example, the location of the imaging spot is the pixel whose total avalanche count is not zero.

[0083] Method 2 for determining the position of the imaging spot: 8.1. Peak finding is performed on the histogram information of each pixel in the pixel block corresponding to the current light source block position of the emitted pulse light and in each pixel block within a preset range around the pixel block; Similar to Method 1, depending on whether a peak can be found in the pixel being searched, the process is divided into two cases, as shown in 8.2 and 8.3 below: 8.2 If no peak is found, the sum of the avalanche counts corresponding to the pixel is 0; 8.3 If a peak can be found, determine the position P of the signal peak; refer to... Figure 15 As shown, the positions of the second left boundary PL2 and the second right boundary PH2 within a preset time range before and after the signal peak are determined; wherein, the second left boundary PL2 is the position of the rising edge of the signal peak being α times the peak height; the second right boundary PH2 is the position of the falling edge being α times the peak height; the position of the rising edge being α times the peak height is the position of the first avalanche count found by moving to the left from the signal peak position being α times the signal peak avalanche count; the second right boundary PH2 is the position of the first avalanche count found by moving to the right from the signal peak position being α times the signal peak avalanche count; Optionally, in step 8.3, the position of the rising edge at α times the peak height can be determined, for example, in the following manner: Moving the search to the left from the signal peak position, if the avalanche count β1 of the j-th time bin in the histogram is greater than α×Γ, and the avalanche count β2 of the adjacent (j-1)-th time bin is less than α×Γ, then the position of the rising edge α times the peak height is calculated as: R_α = j-1 + (α×Γ - β2) / (β1 - β2), α ∈ (0,1); Determine the second left boundary PL2 = R_α.

[0084] Optionally, in step 8.3, the position of the descent along α times the peak height can be determined, for example, in the following manner: Moving the search to the right from the signal peak position, if the avalanche count β1 of the i-th time bin in the histogram is > α × Γ, and the avalanche count β2 of the adjacent (i+1)-th time bin is < α × Γ; then the position of the descent along α times the peak height is calculated as: F_α = i + (α × Γ - β2) / (β1 - β2), α ∈ (0,1); Determine the second right boundary PH2 = F_α.

[0085] The values ​​of α mentioned above are, for example, 0.1, 0.3, 0.5, or 0.7.

[0086] Similar to Method 1, optionally, if the calculated value of PL2 or PH2 is a decimal, the decimal value of PL2 or PH2 is rounded down.

[0087] For example, specific rounding methods can be: PL2 takes the largest integer smaller than it, and PH2 takes the largest integer smaller than it. PL2 takes the largest integer smaller than it, and PH2 takes the smallest integer larger than it. PL2 takes the smallest integer greater than it, and PH2 takes the largest integer less than it. PL2 takes the smallest integer greater than it, and PH2 takes the smallest integer greater than it.

[0088] 8.4 For pixels where a peak can be found, the sum of all avalanche counts within the range [PL2, PH2] in the histogram is used as the total avalanche count of the pixel; 8.5 Determine the location of the imaging spot based on the spatial distribution of the pixel block corresponding to the current emitted pulse light source block position and the sum of the avalanche counts of each pixel in each pixel block within a preset range around the pixel block.

[0089] The location of the imaging spot is determined by the spatial distribution of the total avalanche counts of each pixel. Based on the total number of avalanche counts, the situation can be divided into two cases: 1. If there is only one pixel whose total avalanche count is not zero, then the pixel whose avalanche count is not zero is the location of the imaging spot.

[0090] 2. If there are multiple pixels whose total avalanche count is not zero, then the centroid of the shape formed by the multiple pixels whose avalanche count is not zero is determined as the location of the imaging spot.

[0091] 3. Determine the location of the imaging spot as the pixel with the highest avalanche count among the pixels where the sum of multiple avalanche counts is not 0.

[0092] If no signal light is incident on a pixel, the total avalanche count is zero. Conversely, if a pixel is incident on a signal light, the total avalanche count is not zero. Accordingly, the pixel with a total avalanche count that is not zero is the location of the imaging spot.

[0093] It should be noted that in this embodiment of the invention, a pixel block may contain one pixel or multiple pixels (the number of pixels is greater than 1). Regardless of the number of pixels, the avalanche count is calculated on a pixel-by-pixel basis. That is, for each pixel in the pixel block corresponding to the current pulse light source block position and in each pixel block within a preset range around the current pulse light source block, the avalanche count is calculated separately for each pixel.

[0094] If there are multiple pixels whose avalanche count sum is not 0, it means that the imaging spot spans multiple pixels. The location of the spot can be determined by using the centroids of multiple pixels, or the pixel with the largest avalanche count can be selected as the location of the spot based on the sum of the avalanche counts of several pixels.

[0095] Reference Figure 16 As shown, assuming that the pixel block corresponding to the current pulse light source block position and the pixel blocks within the preset range around the pixel block contain 9 pixels, the avalanche counts of the two pixels with the lower right corner coordinates (4,3) and (4,4) are 200 and 300 respectively, and the avalanche counts of the other pixels are all zero, then the centroid of these two pixels can be used as the position of the light spot, or the position of the pixel (4,4) can be output as the position of the light spot.

[0096] In practical implementation, compared to the technical solution that simultaneously employs both statistical histogram circuits (time-of-flight method) and statistical avalanche counting circuits (triangulation method) for data acquisition, the above embodiments only require the design of one type of circuit in the hardware: the statistical histogram circuit. Subsequent steps, such as calculating the sum of avalanche counts within a preset time range before and after each pixel based on the histogram information, determining the position of the imaging spot based on the spatial distribution of the sum of avalanche counts within a preset time range before and after each pixel's corresponding signal peak, and calculating the offset between the imaging spot and the pixel block corresponding to the light source block, and then calculating the first distance, can all be implemented using a data processing chip. The data acquisition circuit and the data processing chip can be implemented using independent chips, with the data processing chip offering more powerful performance. From a hardware implementation perspective, the technical solution of this embodiment is simpler than the approach of simultaneously using both acquisition circuits.

[0097] From the perspective of finding the location of the imaging spot, in this embodiment of the invention, the total avalanche count corresponding to the pixel with no incident signal light is 0, and conversely, the total avalanche count corresponding to the pixel with incident signal light is not equal to 0. Therefore, the pixel block with a non-zero total avalanche count is the location of the imaging spot. The implementation process is very simple and the result is accurate.

[0098] For the scheme that uses statistical avalanche counting and circuitry to determine the location of the imaging spot, the sum of avalanche counts for pixels without incident signal light is sum_count = (PE - 0) × b, and the sum of avalanche counts for pixels with incident signal light is sum_count = (PE - 0) × b + s. Here, PE can be the right boundary of the histogram time, or a value less than that right boundary but greater than the signal peak position. b is the average count of each bin in the histogram of pixels without incident signal light, representing the average count of each bin caused by ambient light, and s represents the sum of avalanche counts caused by signal light. The comparison between the sum of avalanche counts (sum_count) for pixels with and without incident signal light is not as significant as in this scheme, meaning the signal-to-noise ratio or signal confidence is lower than in the embodiments of this invention, resulting in lower accuracy of the found imaging spot compared to the embodiments of this invention.

[0099] In an optional embodiment, before the above-described peak-finding step of the histogram, in order to improve the accuracy of peak-finding, the embodiment of the present invention may further perform the following steps: Finite Impulse Response (FIR) filtering is applied to the histogram to obtain an FIR histogram, which is then used for peak finding. Compared to the original histogram, the histogram after FIR filtering has a higher signal-to-noise ratio, which helps improve the accuracy of peak finding.

[0100] The length of the FIR filter kernel can be equal to or approximately equal to the width of the laser pulse. There are various values ​​for the filter kernel, such as Gaussian filter kernel and mean filter kernel.

[0101] Based on the same inventive concept, this embodiment of the invention also provides a lidar. Since the lidar provided in this embodiment solves the problem in principle that is similar to the point cloud scanning method of the aforementioned lidar, the implementation of this lidar can refer to the implementation of the aforementioned method, and the repeated parts will not be described again.

[0102] The lidar provided in the embodiments of the present invention refers to... Figure 17 As shown, it includes: multiple liquid crystal phased arrays 171 and a control module 172; The liquid crystal phased array 171 is used to deflect the incident laser beam by a corresponding optical deflection angle according to the applied driving voltage. The control module 172 is used to, for each liquid crystal phased array, obtain the light deflection angle corresponding to the position region of different point cloud angular resolutions within the field of view of the liquid crystal phased array, wherein different light deflection angles correspond to different driving voltages; and apply the driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning.

[0103] In one embodiment, the control module 172 is specifically used to: for each liquid crystal phased array, randomly sort all light deflection angles to determine the scanning order of all light deflection angles; and apply the driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning according to the scanning order of all light deflection angles.

[0104] In one embodiment, the lidar further includes: a transmitter 173, a receiver 174, a data acquisition module 175, a data processing module 176, and a communication module 177; The transmitting end 173 includes multiple light source blocks arranged in a two-dimensional array for emitting light pulses for laser ranging; the multiple light source blocks correspond to the multiple liquid crystal phased arrays 171. The receiving end 174 includes multiple pixel blocks corresponding to the multiple light source blocks, for sensing the echo beam; The control module 172 is also used to control the transmitting end 173 to open the light source block corresponding to the position of the liquid crystal phased array when the driving voltage is applied to the liquid crystal phased array 171; and to control the receiving end 174 to open the pixel block of the sensing echo beam corresponding to the position of the light source block, as well as each pixel block within a preset range around the pixel block of the sensing echo beam. The data acquisition module 175 is used to statistically analyze the histogram information obtained by the induced echo beam of each pixel in each pixel block that is opened for each light deflection angle. The data processing module 176 is used to determine the position of the signal peak in the histogram information of each pixel for each light deflection angle; to count the total avalanche count of each pixel within a preset time range before and after the position of the signal peak; to determine the position of the imaging spot according to the spatial distribution of the total avalanche count within the preset time range before and after the signal peak of each pixel; to determine whether the position of the imaging spot matches the position of the spot corresponding to the light deflection angle in the pre-stored spot image information; and to send the matching result to the communication module 177. The communication module 177 is used to send an alarm message about an abnormal operation of the liquid crystal phased array when the matching result is negative.

[0105] In one embodiment, the lidar further includes: a plurality of light deflection devices 178 corresponding to the plurality of pixel blocks; The control module 172 is further configured to control the light deflection device 178 corresponding to the pixel block of the sensed echo beam to deflect the received echo beam by the same light deflection angle as the corresponding liquid crystal phased array, and, The light deflection devices 178 corresponding to each pixel block within a preset range around the pixel block of the induced echo beam are controlled to deflect the light at the same angle.

[0106] In one embodiment, reference is made to Figure 9 As shown, the lidar also includes a collimating lens and a polarizer sequentially disposed between the corresponding light source blocks and the liquid crystal phased array.

[0107] In one embodiment, the control module 172, the data acquisition module 175, the data processing module 176, and the communication module 177 are each independently configured components; or, The control module 172 is a separately configured component, while the data acquisition module 175, the data processing module 176, and the communication module 177 are integrated into the same component; or... The control module 172 and the communication module 177 are independently configured components, while the data acquisition module 175 and the data processing module 176 are integrated into the same component; or... The control module 172, the data acquisition module 175, the data processing module 176, and the communication module 177 are integrated into the same component.

[0108] Furthermore, the aforementioned data processing module 176 is also used to calculate the offset between the position of the imaging spot and the pixel block corresponding to the light source block, and to calculate the first distance of the target object based on the offset.

[0109] Furthermore, the aforementioned data processing module 176 is also used to obtain the flight time based on the histogram information of the pixels in the pixel block corresponding to the current emitted pulse light source block position, and to calculate the second distance of the target object based on the flight time.

[0110] Furthermore, the data processing module 76 is also used to compare the first distance and the second distance with a preset distance threshold, and select the first distance or the second distance to output based on the comparison result.

[0111] For specific implementations of the control module 172, data acquisition module 175 and data processing module 176 mentioned above, please refer to the specific implementation of the aforementioned point cloud scanning method of lidar, which will not be repeated here.

[0112] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention 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 and optical storage) containing computer-usable program code.

[0113] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A point cloud scanning method for lidar, characterized in that, include: Obtain the light deflection angle corresponding to the position region of different point cloud angular resolutions within the field of view of the lidar, where different light deflection angles correspond to different driving voltages; The driving voltage corresponding to each light deflection angle is applied to the liquid crystal phased array for point cloud scanning.

2. The method as described in claim 1, characterized in that, The step of applying a driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning includes: The scanning order of position regions with different point cloud angular resolutions within the field of view is randomly sorted to determine the arrangement order of all light deflection angles; Following the order of all light deflection angles, the driving voltage corresponding to each light deflection angle is sequentially applied to the liquid crystal phased array for point cloud scanning.

3. The method as described in claim 1, characterized in that, Also includes: Obtain the pre-configured angle hold time after optical deflection; When applying the driving voltage corresponding to each light deflection angle to the liquid crystal phased array, the applied voltage is maintained for the time required to hold the angle after the light deflection.

4. The method according to any one of claims 1-3, characterized in that, Also includes: When a driving voltage is applied to the liquid crystal phased array, the control transmitter opens the light source block corresponding to the position of the liquid crystal phased array.

5. The method as described in claim 4, characterized in that, Also includes: When a driving voltage is applied to the liquid crystal phased array, the control receiver opens the pixel block of the induced echo beam corresponding to the position of the light source block, as well as each pixel block within a preset range around the pixel block of the induced echo beam. For each light deflection angle, the histogram information of the sensed echo beams of each pixel in each pixel block that is opened is statistically analyzed. Based on the histogram information of each pixel, the position of the signal peak in the histogram information is determined; The avalanche count of each pixel within a preset time range before and after the position of the signal peak is counted. Based on the spatial distribution of the avalanche count of each pixel within the preset time range before and after the signal peak, the position of the imaging spot is determined. Determine whether the position of the imaging spot matches the position of the spot with the corresponding light deflection angle in the pre-stored spot image information; if not, send an alarm message for abnormal operation of the liquid crystal phased array.

6. The method as described in claim 5, characterized in that, Also includes: When a driving voltage is applied to the liquid crystal phased array, the light deflection devices corresponding to the pixel blocks of the sensed echo beam are controlled to deflect the echo beam by a corresponding light deflection angle, and, The light deflection devices corresponding to each pixel block within a preset range around the pixel block of the sensed echo beam are controlled to deflect the echo beam by a corresponding light deflection angle.

7. A lidar, characterized in that, include: Multiple LCD phased arrays and control modules; The liquid crystal phased array is used to deflect the incident laser beam by a corresponding optical deflection angle according to the applied driving voltage. The control module is used to obtain, for each liquid crystal phased array, the light deflection angle corresponding to the position region of different point cloud angular resolutions within the field of view of the liquid crystal phased array, wherein different light deflection angles correspond to different driving voltages. The driving voltage corresponding to each light deflection angle is applied to the liquid crystal phased array for point cloud scanning.

8. The lidar as described in claim 7, characterized in that, The control module is specifically used to: for each liquid crystal phased array, randomly sort all light deflection angles to determine the scanning order of all light deflection angles; and apply the driving voltage corresponding to each light deflection angle to the liquid crystal phased array for point cloud scanning according to the scanning order of all light deflection angles.

9. The lidar as described in claim 7 or 8, characterized in that, Also includes: Transmitter, receiver, data acquisition module, data processing module, communication module; The transmitting end includes multiple light source blocks arranged in a two-dimensional array for emitting light pulses for laser ranging; the multiple light source blocks correspond to the multiple liquid crystal phased arrays. The receiving end includes multiple pixel blocks corresponding to the multiple light source blocks, for sensing the echo beam; The control module is further configured to, when controlling the application of a driving voltage to the liquid crystal phased array, control the transmitting end to open the light source block corresponding to the position of the liquid crystal phased array; and control the receiving end to open the pixel block of the induced echo beam corresponding to the position of the light source block, as well as each pixel block within a preset range around the pixel block of the induced echo beam. The data acquisition module is used to statistically analyze the histogram information of the induced echo beams of each pixel in each pixel block that is opened for each light deflection angle. The data processing module is used to determine the position of the signal peak in the histogram information based on the histogram information of each pixel for each light deflection angle. The avalanche count of each pixel within a preset time range before and after the position of the signal peak is counted. Based on the spatial distribution of the avalanche count of each pixel within the preset time range before and after the signal peak, the position of the imaging spot is determined. Determine whether the location of the imaging spot matches the spot location corresponding to the light deflection angle in the pre-stored spot image information, and send the matching result to the communication module; The communication module is used to send an alarm message indicating an abnormal operation of the liquid crystal phased array when the matching result is negative.

10. The lidar as described in claim 9, characterized in that, It also includes: multiple light deflection devices corresponding to the multiple pixel blocks; The control module is further configured to control the optical deflection device corresponding to the pixel block of the sensed echo beam to deflect the received echo beam by the same optical deflection angle as the corresponding liquid crystal phased array, and, The light deflection angles of the light deflection devices corresponding to each pixel block within a preset range around the pixel block of the induced echo beam are controlled to be the same.

Images