Rx end receiving optical power control method and laser radar

Abstract

The invention discloses an Rx end receiving optical power control method and a laser radar, and relates to the technical field of laser radars. Acquiring the position of a light spot directly facing the Rx end of a light beam emitted by the Tx end; and calibrating the offset of the target pixel. And during measurement, controlling the pixel row of the Rx end, which is deviated from the target pixel offset by the position facing the light spot, to be opened so as to receive the light beam emitted by the Tx end. In the method, an opened pixel row is actively shifted at an Rx end, namely, the physical position of a receiving area ROI is actively shifted at the Rx end, so that the relatively strong laser receiving power in one-to-one correspondence with Tx and Rx under the original direct facing condition is further reduced, and the purpose of overall reduction of the receiving optical power is achieved; therefore, the saturation and pileup effect of the received optical signal in a close-range scene with relatively high target reflectivity are relieved, and the distance measurement precision is improved; according to the method, only the target pixel row at the Rx end is controlled to be opened, the number of pixel rows opened at a time is reduced, and energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to a method for controlling received optical power at an Rx end and a laser radar. Background Art

[0002] The LiDAR system is an active detection technology based on the principle of time-of-flight (TOF). It calculates the target distance by emitting laser pulses and measuring their return time. However, in scenarios with close range and high target reflectivity, the LiDAR system faces significant challenges, mainly manifested in the saturation of the received light signal and the pileup effect. The saturation effect will distort the signal waveform and exceed the quantization range of the analog-to-digital converter, making it impossible to accurately measure the real time characteristics of the signal, thereby affecting the accuracy of the distance calculation; in the pileup effect, multiple reflected signals may be superimposed in a short period of time, making it difficult for the receiver to distinguish the real time information of a single signal, affecting the accuracy of the distance measurement.

[0003] In the related technology, the received optical power at the receiving end (Rx end) is reduced by reducing the luminous power at the transmitting end (Tx end), thereby reducing the saturation and pileup effect in close-range and high-reflectivity scenes to improve the distance calculation accuracy in such scenes. However, due to the limitations of the established laser hardware, the laser drive current has a minimum threshold, that is, the laser luminous power has a minimum value, and lower laser power is difficult to obtain at the Tx end, thereby limiting the minimum power received by the Rx end, that is, limiting the dynamic range corresponding to close-range and high-reflectivity scenes.

[0004] It can be seen that providing a new method for reducing the received optical power at the Rx end to alleviate the saturation and pileup effect of the received optical signal, thereby improving the ranging accuracy is a technical problem that personnel in this field continue to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling the received optical power at the Rx end and a laser radar to solve the technical problems of saturation of the received optical signal and pileup effect, which affect the ranging accuracy.

[0006] In order to solve the above technical problems, the present invention provides a method for controlling the received optical power at an Rx end, comprising:

[0007] Get the position of the light spot where the light beam emitted from the Tx end faces the Rx end;

[0008] Calibrate a target pixel offset, wherein the target pixel offset is an offset downward or upward from the position directly facing the light spot according to a preset requirement;

[0009] During measurement, the target pixel row at the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is the pixel row corresponding to the position of the directly facing light spot offset by the target pixel offset.

[0010] Preferably, the calibration target pixel offset comprises:

[0011] Preset N groups of pixel offsets;

[0012] Obtaining N candidate pixel rows corresponding to the N groups of pixel offsets;

[0013] Controlling all the N candidate pixel rows to be opened, and obtaining N intensity histograms corresponding to each of the candidate pixel rows;

[0014] Selecting one from the N intensity histograms as a target histogram;

[0015] A target pixel offset is determined according to the target histogram.

[0016] Preferably, the N groups of pixel offsets are obtained by increasing or decreasing the positions of the facing light spots according to a fixed step size;

[0017] After controlling all the N candidate pixel rows to be opened and obtaining N intensity histograms corresponding to each of the candidate pixel rows, and before selecting one from the N intensity histograms as a target histogram, the method further includes:

[0018] Acquire information for characterizing the optical power received at the Rx end according to the intensity histogram; wherein the information for characterizing the optical power received at the Rx end includes at least the peak height of the maximum waveform of the histogram and the half-height width of the waveform;

[0019] If it is determined based on the information used to characterize the optical power received at the Rx end that the optical power received at the Rx end is fixed and steadily decreasing in rate and is greater than the background intensity, the step of selecting one from the N intensity histograms as the target histogram is entered.

[0020] Preferably, the selecting one from the N intensity histograms as a target histogram comprises:

[0021] Normalizing the N intensity histograms and obtaining N processed histograms;

[0022] From the N processed histograms, find the waveforms where the corresponding N highest peaks are located;

[0023] According to the waveforms where the N highest peaks are located, obtaining N time bin values ​​corresponding to the N highest peaks;

[0024] The N time bin values ​​are compared, the processed histogram with the largest relative time bin is selected, and the corresponding intensity histogram is used as the target histogram.

[0025] Preferably, comparing the N time bin values, selecting the processed histogram with the largest relative time bin, and using the corresponding intensity histogram as the target histogram specifically includes:

[0026] Compare the N time bin values ​​and select the processed histogram with the largest relative time bin;

[0027] If there is more than one processed histogram, the waveform of the incident light is obtained and the waveform of the incident light is normalized;

[0028] An intensity histogram having the same waveform shape as the normalized incident light is obtained and used as the target histogram.

[0029] Preferably, the step of acquiring an intensity histogram having the same waveform shape as the normalized incident light comprises:

[0030] Acquire the half-height width of the waveform of the incident light after normalization processing, and the half-height width of the relatively maximum processed histogram of more than two time bins;

[0031] An intensity histogram having the same half-width as the half-width of the waveform of the incident light after the normalization process is regarded as an intensity histogram having the same shape as the waveform of the incident light after the normalization process.

[0032] Preferably, the controlling the target pixel row at the Rx end to open comprises:

[0033] Get the current pixel row at the Rx end that is facing the light beam emitted by the Tx end;

[0034] Get the number of remaining pixel rows in the scanning direction of the current pixel row on the pixel array;

[0035] Determining whether the number of the remaining pixel rows is greater than or equal to the target pixel offset;

[0036] If yes, then control the pixel row after the current pixel row is shifted by the target pixel offset along the scanning direction to be turned on, so as to realize turning on the target pixel row;

[0037] If not, the pixel row after the current pixel row is shifted by the target pixel offset in the opposite direction of the scanning direction is controlled to be turned on, so as to realize turning on the target pixel row.

[0038] Preferably, the scanning amount each time is k lines, and the target pixel offset amount is 2k lines.

[0039] Preferably, the pixel array includes n rows of pixels, and if it is detected that the number of rows between the current pixel row and the nth pixel row is less than 2k rows, the pixel row offset 2k rows from the current pixel row in the opposite direction of the scanning direction is opened.

[0040] In order to solve the above technical problems, the present invention further provides a laser radar, comprising: a controller, a Tx end and an Rx end, wherein the controller is connected to the Tx end and the Rx end respectively;

[0041] The controller is used to implement the steps of the above-mentioned method for controlling the received optical power at the Rx end.

[0042] The control method of the received optical power at the Rx end provided by the present invention includes: obtaining the position of the light spot facing the Rx end of the light beam emitted by the Tx end; calibrating the target pixel offset. During measurement, the target pixel row at the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is the pixel row corresponding to the position of the light spot offset by the target pixel offset. In this method, by actively offsetting the opened pixel row at the Rx end, that is, actively offsetting the physical position of the receiving area ROI at the Rx end, the Rx end originally facing the Tx end is further reduced by offsetting downward or upward, thereby achieving the purpose of reducing the overall received optical power, thereby alleviating the saturation and pileup effect of the received optical signal in the scene of close distance or / and high target reflectivity, thereby improving the ranging accuracy; and compared with the method of controlling the pixel row of the entire Rx end to be turned on, the target pixel row of the Rx end is controlled to be turned on in the method provided by the present invention, that is, the number of pixel rows turned on at one time is reduced, thereby reducing energy consumption.

[0043] In addition, the present invention also provides a laser radar, in which the controller is used to implement the steps of the above-mentioned method for controlling the received optical power at the Rx end, and has the same beneficial effects as the above-mentioned method for controlling the received optical power at the Rx end. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A flow chart of a method for controlling optical power received at an Rx end provided by an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of a case where Rx is not offset provided by an embodiment of the present invention;

[0047] Figure 3A grayscale image of a Tx-Rx alignment situation provided by an embodiment of the present invention;

[0048] Figure 4 A schematic diagram of laser intensity distribution provided by an embodiment of the present invention;

[0049] Figure 5 A schematic diagram of an Rx offset situation provided by an embodiment of the present invention;

[0050] Figure 6 A histogram under different pixel rows provided by an embodiment of the present invention;

[0051] Figure 7 For Figure 6 The histogram is normalized to obtain the histogram;

[0052] Figure 8 is the original waveform of the incident laser and Figure 7 The diagram shows the shape of the histogram before and after the Tx and Rx offsets. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The core of the present invention is to provide a method for controlling the received optical power at the Rx end and a laser radar to solve the technical problems of saturation and pileup effect of the received optical signal in close distances and / or scenes with high target reflectivity, which affect the ranging accuracy.

[0055] In the related art, the received optical power at the Rx end is reduced by simply reducing the light power at the Tx end, thereby reducing the saturation and pileup effects in close-range, high-reflectivity scenarios to improve the distance calculation accuracy in such scenarios. However, due to the limitations of the established laser hardware, the laser driving current has a minimum threshold, that is, the laser light power has a minimum value, and a lower laser power is difficult to obtain at the Tx end, thereby limiting the minimum power received at the Rx end, that is, limiting the dynamic range corresponding to close-range, high-reflectivity scenarios.

[0056] In order to solve the above problems, the control method of the received optical power at the Rx end provided by the present invention enables the turned-on pixel row at the Rx end originally facing the Tx end to be shifted downward or upward, so that the received power is further reduced, so as to achieve the purpose of overall reduction of received optical power, histogram saturation and alleviation of pileup effect.

[0057] In order to enable those skilled in the art to better understand the solutions of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 1 A flowchart of a method for controlling the optical power received by an Rx end provided in an embodiment of the present invention is shown in FIG. Figure 1 As shown, the method includes:

[0058] S10: Obtain the position of the light spot of the light beam emitted by the Tx end facing the Rx end;

[0059] S11: calibrating a target pixel offset, where the target pixel offset is a downward or upward offset from a position directly facing the light spot according to preset requirements;

[0060] S12: During measurement, the target pixel row at the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is a pixel row corresponding to the light spot position offset by the target pixel offset.

[0061] There is no limitation on preset requirements, which will be determined based on actual conditions. Figure 2 A schematic diagram of a Rx non-deviation situation provided by an embodiment of the present invention. Figure 2 The position of Rx readout in the figure is the position of the light spot where the light beam (Laser) emitted by the Tx end faces the Rx end (sensor). In order to determine whether the light beam emitted by the Tx end faces the Rx end, in the implementation, a grayscale image of the Rx end is obtained after the light beam emitted by the Tx end; if the energy value displayed in the grayscale image is the largest, the pixel with the largest energy value is determined to be the light spot position, which is the position where the light beam emitted by the Tx end faces. Figure 3 A grayscale image of a Tx-Rx alignment condition provided in an embodiment of the present invention. Figure 3 The horizontal axis represents the horizontal spatial position of the receiving end, and the vertical axis represents the vertical spatial position of the receiving end. The alignment between Tx and Rx is shown by different grayscale values, and the white area in the grayscale image represents the facing position. Figure 4 A schematic diagram of laser intensity distribution provided by an embodiment of the present invention. Figure 4 The horizontal coordinate corresponds to Figure 3 The vertical axis represents the longitudinal spatial position in the image, and the vertical axis represents the laser intensity.

[0062] In order to alleviate the saturation and pileup effect of the received light signal in close distance or / and high target reflectivity scenes, and thus improve the ranging accuracy, after determining the position of the light spot facing the Rx end, the target pixel offset is calibrated by the downward or upward offset of the light spot position according to the preset requirements.

[0063] In some embodiments, calibrating the target pixel offset includes:

[0064] Preset N groups of pixel offsets;

[0065] Obtain N candidate pixel rows corresponding to N groups of pixel offsets;

[0066] Control all N candidate pixel rows to be opened, and obtain N intensity histograms corresponding to each candidate pixel row;

[0067] Select one from N intensity histograms as the target histogram;

[0068] According to the target histogram, the target pixel offset is determined.

[0069] There is no limit on the value of the N groups of pixel offsets. For example, if N is 3, the three groups of pixel offsets are 1, 2, and 3. N is 3, which means there are 3 candidate pixel rows. All 3 candidate pixel rows are controlled to be opened and the intensity histogram corresponding to each candidate pixel row is obtained, that is, 3 intensity histograms are obtained. After that, one of the 3 intensity histograms is selected as the target histogram. If the intensity histogram corresponding to the second candidate pixel row is selected as the target histogram, the target pixel offset is determined to be 2. Figure 5 A schematic diagram of an Rx offset situation provided by an embodiment of the present invention, Figure 5 The position of Rx readout is the position where the target pixel row at the Rx end is turned on after the light beam emitted from the Tx end and the Rx end is offset by the target pixel offset.

[0070] In implementation, the N groups of pixel offsets are obtained by increasing or decreasing the position of the light spot according to a fixed step size. The value of the fixed step size is not limited and is determined according to actual conditions. In order to reduce the influence of external light on the result of calibrating the target pixel offset, in some embodiments, after controlling all N candidate pixel rows to be turned on and obtaining N intensity histograms corresponding to each candidate pixel row, before selecting one from the N intensity histograms as the target histogram, it also includes:

[0071] Acquire information for characterizing the optical power received at the Rx end according to the intensity histogram; wherein the information for characterizing the optical power received at the Rx end includes at least the peak height of the maximum waveform of the histogram and the half-height width of the waveform;

[0072] If it is determined based on the information used to characterize the optical power received at the Rx end that the optical power received at the Rx end is fixed and steadily decreasing in rate and is greater than the background intensity, the step of selecting one from the N intensity histograms as the target histogram is entered.

[0073] To determine the target histogram, in some embodiments, selecting one of the N intensity histograms as the target histogram includes:

[0074] Normalizing the N intensity histograms and obtaining N processed histograms;

[0075] From the N processed histograms, find the waveforms with the corresponding N highest peaks;

[0076] According to the waveforms of the N highest peaks, obtain the N time bin values ​​corresponding to the N highest peaks;

[0077] Compare the N time bin values, select the processed histogram with the largest relative time bin, and use the corresponding intensity histogram as the target histogram.

[0078] Among them, compare the N time bin values, select the relatively largest processed histogram of the time bin, and use the corresponding intensity histogram as the target histogram, specifically including:

[0079] Compare N time bin values ​​and select the processed histogram with the largest relative time bin;

[0080] If there is more than one processed histogram, the waveform of the incident light is obtained and the waveform of the incident light is normalized;

[0081] An intensity histogram having the same waveform shape as the normalized incident light is obtained and used as a target histogram.

[0082] In addition, an intensity histogram having the same waveform shape as the normalized incident light is obtained, including:

[0083] Acquire the half-height width of the waveform of the incident light after normalization processing, and the half-height width of the relatively maximum processed histogram of more than two time bins;

[0084] An intensity histogram having the same half-width as the half-width of the waveform of the incident light after normalization processing is regarded as an intensity histogram having the same shape as the waveform of the incident light after normalization processing.

[0085] The process of calibrating the target pixel offset is described above. After the target pixel offset is calibrated, the measurement process is entered. During measurement, the target pixel row at the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is the pixel row corresponding to the light spot position after the target pixel offset is offset. In some embodiments, controlling the target pixel row at the Rx end to be turned on includes:

[0086] Get the current pixel row at the Rx end that is facing the light beam emitted by the Tx end;

[0087] Get the number of remaining pixel rows in the scanning direction of the current pixel row on the pixel array;

[0088] Determine whether the number of remaining pixel rows is greater than or equal to the target pixel offset;

[0089] If yes, then control the pixel row after the current pixel row is offset by the target pixel offset along the scanning direction to be turned on, so as to realize turning on the target pixel row;

[0090] If not, the pixel row after the current pixel row is offset by the target pixel offset in the opposite direction of the scanning direction is controlled to be turned on, so as to realize turning on the target pixel row.

[0091] The scanning amount is k rows each time, and the target pixel offset is 2k rows. Assuming that the pixel array includes n rows of pixels, if it is detected that the number of rows between the current pixel row and the nth pixel row is less than 2k rows, the pixel row offset 2k rows from the current pixel row in the opposite direction of the scanning direction is opened. If n is 50, the scanning amount k is 1 each time, the target pixel offset is 2, and the scanning direction is from top to bottom. When scanning the first row, the first row is scanned. Since the target pixel offset is 2, the pixels in the third row are actually opened; when scanning the second row, the pixels in the fourth row are actually opened; when scanning the third row, the pixels in the fifth row are actually opened; when scanning the 49th row, since there is only one row left, which is less than the target pixel offset of 2, the target pixel offset of 2 is offset in the opposite direction of the scanning direction, that is, when scanning the 49th row, the pixels in the 47th row are actually opened; when scanning the 50th row, the pixels in the 48th row are actually opened.

[0092] In the above-mentioned control method of the received optical power at the Rx end, on the basis of the established optical power at the Tx end, the laser power received by the receiving end is further reduced by actively offsetting the position of the directly facing light spot irradiated on the Rx; in addition, the offset is controlled so that the received optical power is less than the directly facing situation and greater than the background of the non-irradiated area, so as to obtain effective return signal light; and by designing a specific offset of the Tx light spot position for the first and last rows of the scan, it is ensured that the offset of the Rx relative to the Tx irradiation light spot is fixed within the full scanning range.

[0093] In order to enable those skilled in the art to better understand the method of reducing received optical power by staggering SPAD array detectors Tx and Rx of the present invention, the scheme of the present invention is described again below.

[0094] During the operation, first measure the received optical power of Rx in a fixed scenario when Tx and Rx are facing each other (or the corresponding scaled quantity, such as histogram peak height, echo cumulative count, histogram full width at half maximum (FWHM), etc.), and the Rx spot position in the corresponding situation;

[0095] Then, Rx is calibrated with a specific offset test. By actively offsetting a specific number of pixel rows, the final received optical power of Rx (or the corresponding scaled quantity, such as histogram peak height, echo cumulative count, histogram FWHM, etc.) is reduced at a fixed and stable rate, while being significantly greater than the background intensity. The saturation or pileup effect of the histogram data with different reduction ratios is corrected to achieve the purpose of ensuring that the ranging accuracy meets the design requirements.

[0096] Under the premise that the above-mentioned distance measurement indicators meet the requirements, the first and last light-emitting positions of the Tx end are specially designed. When the hardware parameters of the laser and light-emitting module are determined, the incident light spot and the receiving end offset (number of pixels or rolling offset lines, etc.) are determined through calibration, so that the entire scanning area can achieve the same pixel offset through the Rx offset method.

[0097] When the optical power at the Tx end is fixed, the receiving power of the laser at the Rx continues to decrease, so as to further alleviate the data saturation and pileup effect in close-range and high-reflectivity scenarios.

[0098] The method of reducing the received optical power by staggering the SPAD array detectors Tx and Rx of the present invention is described below with reference to a specific embodiment. Figure 6 A histogram of different pixel rows provided by an embodiment of the present invention. Figure 6 The horizontal axis "bin" in the middle refers to the interval or box in the histogram, representing the different segments into which the data range is divided. The vertical axis "normalized" represents normalization, that is, the data is scaled to a specific range after processing, and the Rx-related data is normalized according to certain rules to show the statistical distribution at different pixel rows (V pixel-97 hist, V pixel-103 hist, V pixel-109 hist, and V pixel-115 hist). Assuming that 6 rows of pixels are scanned each time, with a step size of 6 rows of pixels, the strongest intensity histogram received by the Rx end gradually weakens (taking the logarithm of the Y axis to facilitate observation of the degree of intensity reduction). Figure 7 For Figure 6 The histogram is normalized. Figure 7 The horizontal axis "bin" refers to the interval or box in the histogram; the vertical axis "normalized" means normalization. Figure 6The amplitudes of the four histograms in the image are normalized to facilitate the observation of the pileup shape characteristics. By calibrating and calculating the received light intensity, the optimal Rx-Tx staggered pixel number is selected to obtain the best effect of alleviating histogram saturation and pileup compensation; V pixel-97 hist is the histogram obtained by collecting pixels in this row when Tx and Rx are not offset. It can be seen that the peak appears at the front and the pileup phenomenon is the most serious. V pixel-103 hist, V pixel-109 hist, and V pixel-115 hist are the histograms after Rx is offset by 6, 12, and 18 rows relative to Tx; compared with the case where Tx and Rx are not offset, the peaks are all at the back, and the peaks of V pixel-109 hist and V pixel-115 hist are at the back. The pileup effect of the offset histogram is significantly alleviated. Figure 8 is the original waveform of the incident laser and Figure 7 The diagram shows the shape of the histogram before and after the Tx and Rx offsets. Figure 8 The horizontal axis "bin" refers to the interval or box in the histogram; the vertical axis "normalized" means normalization. Figure 8 The histogram shapes of Tx and Rx before and after the offset are compared with the original waveform of the incident laser (using the same bin width as the histogram), and the amplitude is normalized; the closer the histogram is to the incident laser waveform, the smaller the deformation of the received light wave; therefore, V pixel-109 hist is selected, that is, Rx is offset by 12 rows compared to Tx (considering that the received power is lower when offset by 18 rows, which is not conducive to other performance), and the Rx histogram has the best effect in alleviating pileup.

[0099] The control method of the received optical power of the Rx end provided in an embodiment of the present invention includes: obtaining the position of the light spot of the light beam emitted by the Tx end facing the Rx end; calibrating the target pixel offset. During measurement, the target pixel row of the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is the pixel row corresponding to the position of the light spot offset by the target pixel offset. In this method, by actively offsetting the opened pixel row at the Rx end, that is, actively offsetting the physical position of the region of interest (ROI) of the receiving area at the Rx end, the strong laser receiving power of the Tx and Rx in the original one-to-one correspondence under the direct situation is further reduced, thereby achieving the purpose of reducing the overall received optical power, thereby alleviating the saturation and pileup effect of the received optical signal in the scene with high target reflectivity at a close distance, thereby improving the ranging accuracy; and compared with the method of controlling the pixel row of the entire Rx end to be turned on, the method provided by the present invention controls the target pixel row of the Rx end to be turned on, that is, the number of pixel rows turned on at one time is reduced, thereby reducing energy consumption.

[0100] A method for controlling the received optical power of an Rx end is described above. This embodiment further provides a laser radar, including: a controller, a Tx end and an Rx end, wherein the controller is connected to the Tx end and the Rx end respectively;

[0101] The controller is used to implement the steps of the above-mentioned method for controlling the received optical power at the Rx end.

[0102] In the laser radar provided in this embodiment, the controller can implement the control method of the Rx end received optical power described above. The embodiment of the control method of the Rx end received optical power has been described in detail above, and the embodiment of the laser radar will not be repeated here.

[0103] In the laser radar provided by the embodiment of the present invention, the controller is used to obtain the position of the light spot of the light beam emitted by the Tx end facing the Rx end; calibrate the target pixel offset. During measurement, the target pixel row at the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is the pixel row corresponding to the light spot position after the target pixel offset is offset. In the laser radar, the controller actively offsets the opened pixel row at the Rx end, that is, actively offsets the physical position of the receiving area ROI at the Rx end, so that the strong laser receiving power of Tx and Rx in the original one-to-one correspondence under the direct situation is further reduced, thereby achieving the purpose of overall reduction in received light power, thereby alleviating the saturation and pileup effect of the received light signal in the scene with close distance and high target reflectivity, thereby improving the ranging accuracy; and compared with the method of controlling the pixel row of the entire Rx end to be turned on, in the laser radar provided by the present invention, the controller controls the target pixel row of the Rx end to be turned on, that is, the number of pixel rows turned on at one time is reduced, thereby reducing energy consumption.

[0104] The above is a detailed introduction to a method for controlling the received optical power at the Rx end and a laser radar provided by the present invention. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the present invention.

[0105] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A method for controlling the received optical power at an Rx end, characterized in that: include: Get the position of the light spot where the light beam emitted from the Tx end faces the Rx end; Calibrate a target pixel offset, wherein the target pixel offset is an offset downward or upward from the position directly facing the light spot according to a preset requirement; During measurement, the target pixel row at the Rx end is controlled to be turned on to receive the light beam emitted by the Tx end; wherein the target pixel row is the pixel row corresponding to the position of the directly facing light spot offset by the target pixel offset.

2. The method for controlling the received optical power at the Rx end according to claim 1, characterized in that: The calibration target pixel offset comprises: Preset N groups of pixel offsets; Obtaining N candidate pixel rows corresponding to the N groups of pixel offsets; Controlling all the N candidate pixel rows to be opened, and obtaining N intensity histograms corresponding to each of the candidate pixel rows; Selecting one from the N intensity histograms as a target histogram; A target pixel offset is determined according to the target histogram.

3. The method for controlling the received optical power at the Rx end according to claim 2, characterized in that: The N groups of pixel offsets are obtained by increasing or decreasing the positions of the facing light spots according to a fixed step size; After controlling all the N candidate pixel rows to be opened and obtaining N intensity histograms corresponding to each of the candidate pixel rows, and before selecting one from the N intensity histograms as a target histogram, the method further includes: Acquire information for characterizing the optical power received at the Rx end according to the intensity histogram; wherein the information for characterizing the optical power received at the Rx end includes at least the peak height of the maximum waveform of the histogram and the half-height width of the waveform; If it is determined based on the information used to characterize the optical power received at the Rx end that the optical power received at the Rx end is fixed and steadily decreasing in rate and is greater than the background intensity, the step of selecting one from the N intensity histograms as the target histogram is entered.

4. The method for controlling the received optical power at the Rx end according to claim 3, characterized in that: The step of selecting one from the N intensity histograms as a target histogram comprises: Normalizing the N intensity histograms and obtaining N processed histograms; From the N processed histograms, find the waveforms where the corresponding N highest peaks are located; According to the waveforms where the N highest peaks are located, obtaining N time bin values ​​corresponding to the N highest peaks; The N time bin values ​​are compared, the processed histogram with the largest relative time bin is selected, and the corresponding intensity histogram is used as the target histogram.

5. The method for controlling the received optical power at the Rx end according to claim 4, characterized in that: The comparing the N time bin values, selecting the processed histogram with the largest relative time bin, and using the corresponding intensity histogram as the target histogram specifically includes: Compare the N time bin values ​​and select the processed histogram with the largest relative time bin; If there is more than one processed histogram, the waveform of the incident light is obtained and the waveform of the incident light is normalized; An intensity histogram having the same waveform shape as the normalized incident light is obtained and used as the target histogram.

6. The method for controlling the received optical power at the Rx end according to claim 5, characterized in that: The obtaining of an intensity histogram having the same waveform shape as the normalized incident light comprises: Acquire the half-height width of the waveform of the normalized incident light and the half-height width of the relatively maximum processed histogram of more than two time bins; An intensity histogram having the same half-width as the half-width of the waveform of the incident light after the normalization process is regarded as an intensity histogram having the same shape as the waveform of the incident light after the normalization process.

7. The method for controlling the received optical power at the Rx end according to any one of claims 1 to 6, characterized in that: The control of opening the target pixel row at the Rx end includes: Get the current pixel row at the Rx end that the light beam emitted by the Tx end faces; Get the number of remaining pixel rows in the scanning direction of the current pixel row on the pixel array; Determining whether the number of the remaining pixel rows is greater than or equal to the target pixel offset; If yes, then control the pixel row after the current pixel row is shifted by the target pixel offset along the scanning direction to be turned on, so as to realize turning on the target pixel row; If not, the pixel row after the current pixel row is shifted by the target pixel offset in the opposite direction of the scanning direction is controlled to be turned on, so as to realize turning on the target pixel row.

8. The method for controlling the received optical power at the Rx end according to claim 7, characterized in that: The scanning amount each time is k lines, and the target pixel offset is 2k lines.

9. The method for controlling the received optical power at the Rx end according to claim 8, characterized in that: The pixel array includes n rows of pixels. If it is detected that the number of rows between the current pixel row and the nth pixel row is less than 2k rows, the pixel row offset 2k rows from the current pixel row in the opposite direction of the scanning direction is opened.

10. A laser radar, characterized in that: include: A controller, a Tx end and an Rx end, wherein the controller is connected to the Tx end and the Rx end respectively; The controller is used to implement the steps of the method for controlling the received optical power at the Rx end as described in any one of claims 1 to 9.

Images