Sweeper range finding method and device based on dTOF laser radar

Abstract

The invention provides a sweeper ranging method and device based on a dTOF laser radar. The method comprises the following steps: generating a single-point dTOF histogram according to the time difference of transmitting and receiving optical signals by the dTOF laser radar; obtaining an initial peak from the single-point dTOF histogram; respectively calculating confidence coefficients of the initial peaks; judging whether each initial peak has a trailing false peak or not, and marking the confidence coefficient of the trailing false peak as 0; obtaining a bin position POSX and a peak value PeakX of a calibration crosstalk peak of the sweeper outer cover; according to the POSX and the PeakX, whether a crosstalk peak exists in the initial peaks or not is judged, a flag bit representing the dust condition is recognized, and the confidence coefficient of the initial peak with the crosstalk peak and the flag bit not meeting the preset condition is marked as 0; and selecting the peak with the highest confidence in the initial peaks as a confidence peak for output, and calculating the distance of the to-be-measured target through the confidence peak. According to the distance measurement method provided by the invention, the interference caused by excessive dust on the sweeper is avoided, the interference of the trailing false peak of the target peak is removed, and the distance measurement accuracy of the sweeper is improved.

Description

Technical Field

[0001] The present application relates to the field of distance measurement technology, and in particular to a distance measurement method and device for a sweeping machine based on a dTOF laser radar. Background Art

[0002] At present, the application scenarios of dTOF laser radar are becoming more and more extensive, including but not limited to commercial scenarios, home scenarios, outdoor environments, augmented reality technology, as well as smart home and security monitoring. As a fully automatic household cleaning tool, the sweeper has entered thousands of households, and dTOF laser radar has been widely used in various types of sweepers due to its advantages of high ranging accuracy and low cost. However, during the operation of the sweeper, the outer cover is easily contaminated with dirt, which will affect the optical signals emitted and received by the internal dTOF laser radar and interfere with the ranging accuracy. Summary of the invention

[0003] In view of this, the present invention proposes a distance measurement method and device for a sweeping robot based on dTOF laser radar.

[0004] The embodiment of the present application provides a sweeper ranging method based on dTOF laser radar, the method comprising: step S1, generating a single-point dTOF histogram according to the time difference between the dTOF laser radar transmitting and receiving light signals; step S2, reading a plurality of peaks with the largest peak values ​​from the single-point dTOF histogram, and outputting them in bin position order to obtain an initial peak; step S3, calculating the confidence of the initial peak according to the noise level of the single-point dTOF histogram and the peak value of the initial peak; step S4, judging whether each initial peak is a tailing false positive according to the bin position of the initial peak and the relative size of the peak value of the initial peak Peak, mark the initial peak confidence of the trailing false peak as 0; step S5, obtain the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak of the sweeper cover in the single-point dTOF histogram; step S6, according to the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak, determine whether there is a crosstalk peak in the initial peak, and identify the flag bit representing the dust condition, and mark the confidence of the initial peak that has a crosstalk peak and the flag bit does not meet the preset conditions as 0; step S7, select the peak with the highest confidence in the initial peak as the confidence peak output, and calculate the distance of the target to be measured through the confidence peak.

[0005] In some embodiments, the dTOF laser radar includes: a laser, a photoelectric detection avalanche diode, a time-to-digital converter and a processor, and the step 1 specifically includes: step S1.1, the laser transmits N pulse light signals to the target to be measured within a single frame measurement time; step S1.2, the photoelectric detection avalanche diode receives the light signal reflected by the target to be measured; step S1.3, the time-to-digital converter records the flight time between the emission and reception of the light signal; step S1.4, the processor performs histogram statistics on the N flight times, and generates a single-point dTOF histogram through low-pass filtering.

[0006] In some embodiments, step S2 specifically includes: step S2.1, traversing the generated single-point dTOF histogram, and selecting all peaks that meet the three-point peak condition; step S2.2, arranging all peaks that meet the conditions from large to small according to the peak value, and selecting several peaks with the largest peaks as initial peaks; step S2.3, rearranging the initial peaks from front to back according to their bin position order, and outputting them.

[0007] In some embodiments, step S3 specifically includes: obtaining the confidence of each initial peak by calculating the ratio of each initial peak-to-peak value to the single-point dTOF histogram noise.

[0008] In some embodiments, step S4 specifically includes: calculating the slope of the peak line connecting each initial peak and each subsequent initial peak in turn; when the slope is lower than a threshold, taking the initial peak at the subsequent bin position as the tailing false peak of the initial peak at the previous bin position; and marking the confidence of the tailing false peak as 0.

[0009] In some embodiments, in step S5, the marking process of the calibrated crosstalk peak of the sweeper cover includes: step S5.1, truncating the single-point dTOF histogram at a preset position; step S5.2, traversing the truncated single-point dTOF histogram, selecting all peaks that meet the peak formation conditions and outputting them in sequence; step S5.3, selecting a peak with the largest peak value as the calibrated crosstalk peak, and outputting the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak in the single-point dTOF histogram.

[0010] In some embodiments, step S6 specifically includes: step S6.1, initializing the flag bit representing the dust condition to 0, obtaining the redundancy gap1 representing the bin position and the redundancy gap2 representing the dust identification position, as well as the threshold ratio of the peak value; step S6.2, when the peak value of an initial peak is less than Peak_X, and the bin position of the initial peak-to-peak value is less than POS_X+gap1, identifying the initial peak as a crosstalk peak; step S6.3, when the peak value of an initial peak is greater than Peak_X, if the bin position of the initial peak-to-peak value is less than POS_X+gap2, and its peak value is greater than Peak_X×ratio, setting the flag bit to 2, and judging that the flag bit meets the preset conditions; step S6.4, marking the confidence of the initial peak that has a crosstalk peak and whose flag bit does not meet the preset conditions as 0.

[0011] In some embodiments, step S7 specifically includes: converting the bin position of the confidence peak into a length unit and outputting the unit to obtain the distance of the target to be measured.

[0012] The embodiment of the present application provides a sweeper ranging device based on dTOF laser radar, the device comprising: a dTOF laser radar, used to generate a single-point dTOF histogram according to the time difference between the single-point dTOF laser radar transmitting and receiving light signals; a reading unit, used to read a plurality of peaks with the largest peak values ​​from the single-point dTOF histogram, and output them in bin position order to obtain an initial peak; a confidence calculation unit, used to calculate the confidence of the initial peak according to the noise level of the single-point dTOF histogram and the peak value of the initial peak; a tailing false peak judgment unit, used to judge the confidence of the initial peak according to the bin position of the initial peak and the relative size of the peak value of the initial peak. Whether there is a false tailing peak for each initial peak, the confidence of the false tailing peak is marked as 0; a crosstalk peak judgment unit is used to obtain the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak of the sweeper cover in the single-point dTOF histogram; according to the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak, it is judged whether there is a crosstalk peak in the initial peak, and the flag bit representing the dust condition is identified, and the confidence of the initial peak with a crosstalk peak and a flag bit that meets the preset conditions is marked as 0; a calculation unit is used to select the peak with the highest confidence in the initial peak as the confidence peak output, and the distance of the target to be measured is obtained by calculating the confidence peak.

[0013] The sweeper ranging method based on dTOF laser radar provided in the embodiment of the present application can be applied to the sweeper to avoid interference caused by excessive dust on the sweeper cover, improve the accuracy of the sweeper ranging, and remove the interference of the tailing false peak of the target peak, thereby improving the accuracy of the sweeper ranging. In addition, the present invention is applicable to covers of different distances and different structures, and can handle and deal with different degrees of dirt on the cover, and has versatility and robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of a flow chart of a sweeper ranging method based on a dTOF laser radar provided in an embodiment of the present application;

[0015] Figure 2 A schematic diagram of a histogram containing 4 obvious signal peaks provided in an embodiment of the present application;

[0016] Figure 3 An example diagram of calculating tailing false peaks provided in an embodiment of the present application;

[0017] Figure 4 A schematic diagram of peak formation conditions provided in the embodiments of the present application;

[0018] Figures 5 to 8 Schematic diagram of the judgment process of step S6 in the embodiment of the present application. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer based on the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0020] In lidar ranging, histogram is an important means to calculate the distance of the target to be measured. The ranging principle of dToF is as follows: the transmitter emits a light beam to the ranging area. The emitted light beam reaches the target object and is reflected by the target object to form a reflected light beam. Part of the photon signal of the reflected light beam is received by the receiving end, and each single photon in the photon signal is incident on the SPAD array (avalanche photodiode) to generate an avalanche signal. Then the SAPD outputs the avalanche signal to the TDC, and the TDC detects the time interval from the transmitter to the avalanche. The histogram counting statistics of each photon are performed according to the time interval of each photon. The final statistical histogram is formed. The ordinate of the histogram represents the peak value, and the ordinate represents the bin position. The time corresponding to the peak value is used to determine the time T required for the light beam to be emitted by the transmitter and received by the receiver, thereby completing the ranging process.

[0021] The present application embodiment provides a sweeper ranging method based on dTOF laser radar. Figure 1 For a flow chart of a sweeper ranging method based on dTOF laser radar provided in an embodiment of the present application, see Figure 1 , the method comprising:

[0022] Step S1, generating a single-point dTOF histogram according to the time difference between the single-point dTOF laser radar transmitting and receiving light signals. In the embodiment of the present application, the dTOF laser radar includes: a laser, a photoelectric detection avalanche diode, a time-to-digital converter and a processor, and the step 1 specifically includes:

[0023] Step S1.1, the laser emits N pulse light signals to the target to be measured within a single frame measurement time; Step S1.2, the photoelectric detection avalanche diode receives the light signal reflected by the target to be measured; Step S1.3, the time-to-digital converter records the flight time between the emission and reception of the light signal; Step S1.4, the processor performs histogram statistics on the N times of flight time to obtain the original dTOF histogram, and generates a single-point dTOF histogram after low-pass filtering. Here, the original dTOF histogram has a total of 1024 bins, and the LSB (Least Significant Bit) of each bin is 104ps, which is converted to a length unit of 15.5mm using the speed of light. It can be calculated that the theoretical maximum distance measurement capability of this example can reach 15.9m, which can meet the application requirements of most sweeping robots. Finally, the original dTOF histogram is low-pass filtered using a window of length 16 to suppress the influence of noise and improve the ranging accuracy.

[0024] Step S2, read several peaks with the largest peaks from the single-point dTOF histogram. In this embodiment, the three largest peaks are read and output in order of bin positions to obtain the initial peaks. In this embodiment of the present application, step S2 specifically includes: step S21, traverse the single-point dTOF histogram, select all peaks that meet the three-point peak condition; step S22, arrange all peaks that meet the condition from large to small according to the peak value, and select the three signal peaks with the largest peak value as the initial peaks, Figure 2 A histogram diagram containing 4 obvious signal peaks provided in the embodiment of the present application is shown as follows: Figure 2 As shown in the figure, in the histogram, the three peaks with the highest peaks are used as the initial peaks, and the output order from the largest to the smallest peaks is: (303, 4330), (803, 3483), (103, 1782). Step S23, rearrange the three initial peaks from front to back according to the bin position order, and output them. The output order of the initial peaks from front to back according to the bin position order is (103, 1782), (304, 4330), (804, 3483).

[0025] Step S3, calculate the confidence of the initial peak respectively according to the noise level of the single-point dTOF histogram and the peak size of the initial peak; here, for the output initial peak, its credibility needs to have a measurement standard. In the present invention, the confidence is used to describe the credibility of each peak. When the confidence is 100, the peak is considered to be a credible signal peak. When the confidence is 0, the peak is considered to be unreliable and not a signal peak; when the confidence is between 0 and 100, the confidence characterizes the credibility of the peak. The embodiment of the present application calculates the confidence of the three peaks respectively according to the noise level of the single-point dTOF histogram and the peak size of the initial peak. Step S3 specifically includes: obtaining the confidence of each initial peak by calculating the ratio of the peak value of each initial peak to the noise of the single-point dTOF histogram. Here, the process of calculating the confidence of each initial peak includes:

[0026] if peak value>=upper

[0027] Confidence = 100;

[0028] else if peak <= lower

[0029] confidence=0;

[0030] else

[0031] Confidence = 100 × (peak - lower) / (upper - lower);

[0032] End

[0033] Here, when the ratio is higher than the preset ratio upper, the confidence of the initial peak is marked as 100, and when the ratio is lower than the preset ratio lower, the confidence of the initial peak is marked as 0; if the ratio is between upper and lower, the confidence is calculated as a corresponding value between 100 and 0.

[0034] Due to the ringing phenomenon of dTOF laser radar well known to those skilled in the art, there will be tailing false peaks in the tail of the signal peak of the dTOF histogram. Step S4 is to determine whether there are abnormal tailing false peaks and mark them according to the relative position of the initial peak in the histogram and the relative size of the peak. Step S4, according to the bin position of the initial peak and the relative size of the initial peak-peak value, determine whether each initial peak is a tailing false peak, and mark the initial peak confidence of the tailing false peak as 0. Here, step S4 specifically includes: calculating the slope of the line connecting each initial peak and the peak value of each subsequent initial peak in turn; when the slope is lower than the threshold, the initial peak at the next bin position is used as the tailing false peak of the initial peak at the previous bin position; the confidence of the tailing false peak is marked as 0. For example, the three initial peaks are arranged in order according to the bin position: the front peak, the middle peak and the last peak. First, the slope of the peak line connecting the front peak and the middle peak is calculated. If the slope is higher than the threshold, the middle peak is regarded as the tailing false peak of the front peak, and the confidence of the middle peak of the tailing false peak is marked as 0. Figure 3 For an example diagram of calculating tailing false peaks provided in the embodiment of the present application, see Figure 3 , Figure 3 A portion of the single-point dTOF histogram is intercepted in , (103, 1193) is the front peak, (127, 493) is the middle peak, the peak values ​​of the front peak and the middle peak are connected, and the slope of the line is calculated. When the absolute value of the slope exceeds the threshold value Th, it means that the slope of the line connecting the middle peak and the front peak is large, and the middle peak is judged as the tailing false peak of the front peak, and its confidence is marked as 0. Then the slope of the line connecting the front peak and the last peak is calculated. If the slope is higher than the threshold, the last peak is considered to be the tailing peak of the front peak, and the confidence of the last peak is marked as 0. Then the slope of the peak line connecting the middle peak and the last peak is calculated. If the slope is higher than the threshold, the last peak is considered to be the tailing false peak of the middle peak, and the confidence of the last peak is marked as 0.

[0035] Step S5, obtain the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak of the sweeping machine cover in the single-point dTOF histogram. When the sweeping machine product leaves the factory, the sweeping machine cover will be calibrated, and the peak value and position of the crosstalk peak generated by the cover will be saved to facilitate the next step of dust identification. The calibrated crosstalk peak of the sweeping machine cover obtained here is the one obtained by the factory calibration of the sweeping machine. The marking process, i.e., step S5, specifically includes the following steps:

[0036] Step S5.1, truncate the single-point dTOF histogram at a preset position. The preset position here needs to be determined according to the distance between the outer cover of the sweeper and the laser radar. In the embodiment of the present application, the default truncation position is 60 cm. Configure the truncation position externally first, and then execute step S5.2.

[0037] Step S5.2, traverse the truncated single-point dTOF histogram, select all peaks that meet the peak formation conditions and output them in order; here, all peaks that meet the peak formation conditions are output in order from small to large. In this embodiment, the peak formation conditions are as follows: Figure 4 As shown, see Figure 4 The peak formation condition is a three-point peak, that is, in one peak, there are low values ​​Pn-1 and Pn+i at the two end points, and a high value Pn+i-1 between the low values ​​Pn-1 and Pn+i. i is a positive integer greater than or equal to 1. For example, the low values ​​of the two end points are Pn-1 and Pn+3 respectively, then there are three high values ​​Pn, Pn+1, and Pn+2.

[0038] Step S5.3, selecting a peak with the largest peak value as the calibration crosstalk peak, and outputting the bin position POS_X and the peak value Peak_X of the calibration crosstalk peak in the single-point dTOF histogram.

[0039] Since the outer cover will be contaminated with dirt during the operation of the sweeper, thus forming a large crosstalk peak, which affects the distance measurement, it is necessary to identify the crosstalk peak and delete it. After obtaining the position and size of the crosstalk peak caused by the outer cover, determine whether there is a crosstalk peak in the initial peak after deleting the false trailing peak, identify the dust condition, and upload the flag to the whole machine. Step S6, based on the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak, determine whether there is a crosstalk peak in the initial peak, identify the flag representing the dust condition, and mark the confidence of the initial peak with a crosstalk peak and a flag that does not meet the preset conditions as 0. Step S6 specifically includes:

[0040] Step S6.1, initialize the flag representing the dust condition to 0, obtain the redundancy gap1 representing the bin position and the redundancy gap2 representing the dust identification position, as well as the threshold ratio ratio of the peak value. Here, the initialization flag is 0, indicating that there is no dust or slight dust on the outer cover at this time. gap1 can be configured as a positive integer between 2 and 8, and the threshold ratio ratio of the peak value can be configured as a value between 0 and 1. gap2 can be configured as a positive integer, and the value of gap2 cannot be greater than the minimum value between gap1 and 5. In the embodiment of the present application, gap1 defaults to 5, ratio defaults to 0.5, and gap2 defaults to 2.

[0041] Step S6.2: When the peak value of an initial peak is less than Peak_X, and the bin position of the initial peak-to-peak value is less than POS_X+gap1, the initial peak is identified as a crosstalk peak. Step S6.3: When the peak value of an initial peak is greater than Peak_X, if the bin position of the initial peak-to-peak value is less than POS_X+gap2, and its peak value is greater than Peak_X×ratio, the flag bit is set to 2, and it is determined whether the flag bit meets the preset condition. The preset condition here is whether the flag bit is 2. When the flag bit is 2, the preset condition is met, indicating that there is a large signal at a close distance at this time. It is not sure whether it is caused by a close target or too much dust on the outer cover. Other modules of the whole machine need to make a joint judgment.

[0042] Step S6.4, mark the confidence of the initial peak that has a crosstalk peak and the flag bit does not meet the preset conditions as 0. For each initial peak, determine whether its peak value is less than Peak_X, and whether its bin position in the histogram is less than POS_X+gap1. When both are satisfied, the initial peak is considered to be a crosstalk peak generated by the outer cover. Then determine whether the crosstalk peak value satisfies greater than Peak_X×ratio. When the peak value is less than Peak_X×ratio, the flag bit remains unchanged at 0; when the peak value is greater than Peak_X×ratio, the flag bit is set to 1. If the flag bit is 0 or 1, it is judged that the flag bit does not meet the preset conditions, indicating that there is dust on the outer cover at this time, the initial peak has a crosstalk peak and the flag bit does not meet the preset body condition (that is, the flag bit is not 2), and its peak value and confidence are set to 0, that is, the crosstalk peak is deleted.

[0043] Figures 5 to 8 Schematic diagram of the judgment process of step S6 in the embodiment of the present application, as shown in Figure 5 As shown, the crosstalk peak (i.e. Figure 4 The peak in the calibration is (63,571), and the front peak measured (i.e. Figure 5 The measured peak in the figure is (73, 3517). At this time, there is no peak that satisfies both the peak value less than Peak_X and the position less than POS_X+gap1, that is, there is no crosstalk peak, and the flag bit is still 0, indicating that there is no dust on the outer cover at this time.

[0044] like Figure 6 As shown, the crosstalk peak (i.e. Figure 6 The peak in the calibration is (63,567), and the front peak measured (i.e. Figure 5 The measured peak in the figure is (67, 536). This peak satisfies both the peak value less than Peak_X and the position less than POS_X+gap1. The peak is identified as a crosstalk peak, and then the peak value of the peak is judged to be greater than ratio×Peak_X. The flag position is set to 1. At this time, the flag is judged to not meet the preset conditions, and its peak value and confidence are set to 0, indicating that there is a lot of dust in the outer cover at this time.

[0045] like Figure 7 As shown, the crosstalk peak (i.e. Figure 7 The peak in the calibration is (63, 603), and the front peak measured (i.e. Figure 7 The measured peak in the figure is (67, 262). This peak satisfies both the peak value less than Peak_X and the position less than POS_X+gap1. The peak is identified as a crosstalk peak, but the peak value of the peak is less than ratio×Peak_X, and the flag is still 0. It is judged that the flag does not meet the preset conditions, and the peak value and confidence are marked as 0, indicating that there is less dust in the outer cover at this time.

[0046] like Figure 8 As shown, the crosstalk peak (i.e. Figure 8 The peak in the calibration is (63,581), and the most front peak measured (i.e. Figure 8 The actual measured peak in the figure is (64, 747), which is greater than Peak_X. At this time, continue to judge according to step S6.3. The peak-to-peak bin position is less than POS_X+gap2 and the peak is greater than ratio×Peak_X. Set the flag bit to 2, and judge that the flag bit meets the preset conditions, indicating that there is a large peak at close range. It is not sure whether it is caused by a close-range target or too much dust on the outer cover of the sweeper. It is necessary to combine other modules of the whole machine for judgment.

[0047] Step S7, select the peak with the highest confidence in the initial peak as the confidence peak output, and calculate the distance of the target to be measured by the confidence peak. Through the above steps S1-S6, the confidence of some initial peaks that do not meet the conditions has been marked as 0. Therefore, next, only the peak with the highest confidence in the remaining initial peaks is selected as the confidence peak output. Step S7 specifically includes: converting the bin position of the confidence peak into a length unit and outputting it to obtain the distance of the target to be measured. The conversion formula is shown in formula (1):

[0048] TOF = POS × LSB × C / 2 (1)

[0049] Wherein, POS represents the bin position of the confidence peak finally selected, LSB is the length of each time interval, which is 104 ps in the embodiment of the present application, and C represents the speed of light in vacuum.

[0050] The sweeper ranging method based on dTOF laser radar provided in the embodiment of the present application can not only avoid the interference caused by excessive dust on the sweeper cover in the sweeper application, but also remove the interference of the tailing false peak of the target peak, thereby improving the accuracy of the sweeper ranging. In addition, the ranging method provided by the present invention can be applied to sweeper covers of different distances and different structures, and can handle and deal with different degrees of dirt on the cover. Moreover, since multiple peaks are taken into account, in complex scenes with mirrors and glass, it can avoid obstacles by selecting the most forward signal peak, and has versatility and robustness.

[0051] The embodiment of the present application provides a distance measuring device for a sweeping machine based on a dTOF laser radar, the device comprising:

[0052] The dTOF laser radar is used to generate a single-point dTOF histogram according to the time difference between the single-point dTOF laser radar transmitting and receiving light signals; the reading unit is used to read a plurality of peaks with the largest peak values ​​from the single-point dTOF histogram, and output them in bin position order to obtain an initial peak; the confidence calculation unit is used to calculate the confidence of the initial peak according to the noise level of the single-point dTOF histogram and the peak value of the initial peak; the tailing false peak judgment unit is used to judge whether each initial peak has a tailing false peak according to the bin position of the initial peak and the relative size of the peak value of the initial peak, and ... The confidence of the false tail peak is marked as 0; a crosstalk peak judgment unit is used to obtain the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak of the sweeper cover in the single-point dTOF histogram; according to the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak, it is judged whether there is a crosstalk peak in the initial peak, and the flag bit representing the dust condition is identified, and the confidence of the initial peak with a crosstalk peak and a flag bit that meets the preset conditions is marked as 0; a calculation unit is used to select the peak with the highest confidence in the initial peak as the confidence peak output, and the distance of the target to be measured is calculated by the confidence peak.

[0053] In some embodiments, the dTOF laser radar includes: a laser, a photoelectric detection avalanche diode, a time-to-digital converter and a processor, wherein the laser is used to transmit N pulse light signals to the target to be measured within a single frame measurement time; the photoelectric detection avalanche diode is used to receive the light signal reflected by the target to be measured; the time-to-digital converter is used to record the flight time between the emission and reception of the light signal; the processor is used to make a histogram statistics of the N flight times, and generate a single-point dTOF histogram through low-pass filtering.

[0054] An embodiment of the present application provides a computer-readable storage medium, which stores an executable program. When the executable program is executed by a processor, it implements any of the above-mentioned dTOF laser radar-based sweeper ranging methods.

[0055] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The above description is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any technician familiar with the profession may make various changes, modifications, substitutions and variations to these embodiments without departing from the principle and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A sweeper distance measurement method based on dTOF laser radar, characterized in that: The method comprises: Step S1, generating a single-point dTOF histogram according to the time difference between the dTOF laser radar transmitting and receiving light signals; Step S2, reading a plurality of peaks with the largest peak values ​​from the single-point dTOF histogram, and outputting them in bin position order to obtain an initial peak; Step S3, calculating the confidence of each initial peak according to the noise level of the single-point dTOF histogram and the peak value of the initial peak; Step S4, judging whether each initial peak is a tailing false peak according to the bin position of the initial peak and the relative size of the initial peak-peak value, and marking the initial peak confidence of the tailing false peak as 0; Step S5, obtaining the bin position POS_X and the peak value Peak_X of the calibrated crosstalk peak of the sweeping machine cover in the single-point dTOF histogram; Step S6, judging whether there is a crosstalk peak in the initial peak according to the bin position POS_X and the peak value Peak_X of the calibrated crosstalk peak, identifying the flag representing the dust condition, and marking the confidence of the initial peak with a crosstalk peak and the flag not meeting the preset condition as 0; Step S7, selecting the peak with the highest confidence in the initial peaks as the confidence peak output, and calculating the distance of the target to be measured through the confidence peak.

2. The method according to claim 1, characterized in that The dTOF laser radar includes: a laser, a photoelectric detection avalanche diode, a time-to-digital converter and a processor, and the step 1 specifically includes: Step S1.1, the laser emits N pulse light signals to the target to be measured within a single frame measurement time; Step S1.2, the photoelectric detection avalanche diode receives the light signal reflected by the target to be detected; Step S1.3, the time-to-digital converter records the flight time between the transmitted and received light signals; Step S1.4: The processor performs histogram statistics on the N times of flight time and generates a single-point dTOF histogram through low-pass filtering.

3. The method according to claim 2, characterized in that Step S2 specifically includes: Step S2.1, traverse the generated single-point dTOF histogram and select all peaks that meet the peak formation conditions; Step S2.2, all peaks meeting the conditions are arranged in descending order of peak value, and several peaks with the largest peak values ​​are selected as initial peaks; Step S2.3, rearrange the initial peaks from front to back according to their bin position order, and output them.

4. The method according to claim 3, characterized in that Step S3 specifically includes: The confidence level of each initial peak was obtained by calculating the ratio of the peak value of each initial peak to the noise of the single-point dTOF histogram.

5. The method according to claim 3, characterized in that: Step S4 specifically includes: Calculate the slope of the line connecting each initial peak and each subsequent initial peak in sequence; When the slope is lower than the threshold, the initial peak at the next bin position is taken as the tailing false peak of the initial peak at the previous bin position; The confidence level of the tailing pseudo-peak is marked as 0.

6. The method according to claim 3, characterized in that: In step S5, the marking process of the calibrated crosstalk peak of the sweeper cover includes: Step S5.1, truncating the single-point dTOF histogram at a preset position; Step S5.2, traverse the truncated single-point dTOF histogram, select all peaks that meet the peak formation conditions and output them in order; Step S5.3, selecting a peak with the largest peak value as the calibration crosstalk peak, and outputting the bin position POS_X and the peak value Peak_X of the calibration crosstalk peak in the single-point dTOF histogram.

7. The method according to claim 3, characterized in that Step S6 specifically includes: Step S6.1, initializing the flag bit representing the dust condition to 0, obtaining the redundancy gap1 representing the bin position and the redundancy gap2 representing the dust identification position, and the threshold ratio ratio of the peak value; Step S6.2, when the peak value of a certain initial peak is less than Peak_X, and the bin position of the peak value of the initial peak is less than POS_X+gap1, the initial peak is identified as a crosstalk peak; Step S6.3, when the peak value of a certain initial peak is greater than Peak_X, if the initial peak-to-peak bin position is less than POS_X+gap2, and its peak value is greater than Peak_X×ratio, set the flag bit to 2, and judge that the flag bit meets the preset condition; Step S6.4, marking the confidence of the initial peak with a crosstalk peak and a flag bit that does not meet the preset condition as 0.

8. The method according to claim 3, characterized in that Step S7 specifically includes: The bin position of the confidence peak is converted into a length unit and outputted to obtain the distance of the target to be measured.

9. A sweeper distance measuring device based on dTOF laser radar, characterized in that: The device comprises: dTOF laser radar, used to generate a single-point dTOF histogram according to the time difference between the single-point dTOF laser radar transmitting and receiving light signals; A reading unit, used for reading a plurality of peaks with the largest peak values ​​from the single-point dTOF histogram, and outputting them in bin position order to obtain an initial peak; A confidence calculation unit, used to calculate the confidence of the initial peak according to the noise level of the single-point dTOF histogram and the peak value of the initial peak; A tailing false peak judgment unit, used to judge whether each initial peak is a tailing false peak according to the bin position of the initial peak and the relative size of the initial peak-peak value, and mark the initial peak confidence of the tailing false peak as 0; The crosstalk peak judgment unit is used to obtain the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak of the sweeper cover in the single-point dTOF histogram; according to the bin position POS_X and peak value Peak_X of the calibrated crosstalk peak, it is judged whether there is a crosstalk peak in the initial peak, and the flag bit representing the dust condition is identified, and the confidence of the initial peak with the crosstalk peak and the flag bit meeting the preset condition is marked as 0; The calculation unit is used to select the peak with the highest confidence in the initial peaks as the confidence peak output, and calculate the distance of the target to be measured through the confidence peak.

10. A computer-readable storage medium storing an executable program, characterized in that: When the executable program is executed by a processor, the sweeper ranging method based on dTOF laser radar as described in any one of claims 1 to 8 is implemented.

Images