A pulsed laser range finder and a laser ranging method thereof

Abstract

The application relates to a pulsed laser range finder and a laser ranging method thereof. The range finder comprises a receiving module, which collects continuous signals after emitting a detection laser pulse to a target object, and divides a plurality of convex waveforms from the continuous signals according to an intensity threshold; an analysis module, which analyzes the shape features of each convex waveform, obtains the confidence of each convex waveform, and screens a plurality of real echoes from the plurality of convex waveforms according to the confidence; a determination module, which determines the real return moment corresponding to each real echo according to the signal intensity distribution center on the waveform of each real echo; and a calculation module, which calculates the actual distance corresponding to each real echo according to the difference between the real return moment corresponding to each real echo and the laser emission moment. The application can improve the measurement stability and ranging precision of the range finder under complex working conditions.

Description

Technical Field

[0001] This application relates to the field of laser ranging technology, and in particular to a pulsed laser rangefinder and its laser ranging method. Background Technology

[0002] With the rapid development of intelligent manufacturing and automated warehousing and logistics, industrial-grade laser rangefinders, safety lidar, and other measuring instruments are widely used in core equipment such as automated guided vehicles, autonomous mobile robots, six-axis flexible robotic arms, and CNC machining centers. As a core component of high-end equipment, the rangefinder's measurement stability and reliability under complex and changing working conditions determine the safety of the entire automated system.

[0003] In complex industrial environments, equipment operating spaces are often filled with high concentrations of suspended interference, such as metal fumes in welding workshops and cutting fluid mist sprayed from machining centers. Because existing ranging instruments generally employ a first-hit-through detection mechanism, when a laser pulse travels through the air and passes through metal fumes or cutting fluid mist, the surfaces of these semi-transparent media produce weak optical diffuse reflection. If existing instruments detect even a slight reflected light level exceeding the hardware-set extremely low noise threshold, they immediately cut off the receiving window for that measurement, mistakenly identifying this thin layer of mist or glass as the final obstacle. This results in frequent false alarms in complex industrial environments. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a pulsed laser rangefinder and its laser ranging method. The specific technical solution adopted is as follows: In a first aspect, a pulsed laser rangefinder and a laser ranging method thereof are provided, the rangefinder comprising: The receiving module is used to acquire a continuous signal after emitting a probe laser pulse at the target object, and to segment multiple raised waveforms from the continuous signal according to an intensity threshold; wherein the intensity threshold is determined by the ambient light acquired before emitting the probe laser pulse. The analysis module is used to analyze the morphological characteristics of each convex waveform, obtain the confidence level of each convex waveform, and filter out multiple true echoes from multiple convex waveforms based on the confidence level. The morphological characteristics of the convex waveform include the pulse width and peak height of the convex waveform, and the confidence level represents the degree of correlation between the convex waveform and the target object. The determination module is used to determine the true return time corresponding to each true echo based on the signal intensity distribution center on the waveform of each true echo; The calculation module is used to calculate the actual distance corresponding to each real echo based on the difference between the real return time and the laser emission time corresponding to each real echo.

[0005] Optionally, after emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple convex waveforms are segmented from the continuous signal according to an intensity threshold, including: Before emitting a detection laser pulse to the target object, multiple ambient light samples are collected, and the preset effective threshold is corrected based on the average value of the multiple ambient light intensities to obtain the intensity threshold. The theoretical flight time corresponding to the target ranging distance is combined with the preset safety margin duration to obtain the opening duration of the receiving channel; After emitting a detection laser pulse at the target object, the continuous signal is acquired during the opening time of the receiving channel; The moment when the signal strength in the continuous signal is greater than the strength threshold from bottom to top is taken as the start time of the corresponding convex waveform, and the moment when the signal strength in the continuous signal is less than the strength threshold from top to bottom is taken as the end time of the corresponding convex waveform, thus obtaining multiple convex waveforms; wherein the signal strength in the convex waveform is greater than the strength threshold.

[0006] Optionally, the morphological characteristics of each convex waveform are analyzed to obtain the confidence level of each convex waveform, and multiple true echoes are obtained from multiple convex waveforms based on the confidence level, including: The echo concentration of each convex waveform is calculated based on the degree of negative correlation between the pulse width of each convex waveform and its energy distribution. The confidence level of each convex waveform is obtained by fusing its energy sharpness with its echo concentration. The energy sharpness of each convex waveform characterizes the sharpness of the signal intensity within the convex waveform, and is obtained by analyzing the peak height and pulse width of each convex waveform. A bulge waveform with a confidence level greater than a preset confidence threshold is identified as a true echo.

[0007] Optionally, based on the correlation between the pulse width of each bulge waveform and its energy distribution, the echo concentration of each bulge waveform is calculated, including: The difference between the signal strength and the strength threshold at each moment within each convex waveform is accumulated to obtain the energy accumulation value of each convex waveform; The echo concentration of each convex waveform is obtained by calculating the ratio of the cumulative energy value within each convex waveform to the square of its pulse width; the echo concentration characterizes the degree of energy concentration of the convex waveform.

[0008] Optionally, the energy sharpness of each bulge waveform is fused with its echo concentration to obtain the confidence level of each bulge waveform, including: Calculate the ratio of the peak height to the pulse width within each bulge waveform to obtain the energy sharpness of each bulge waveform; The confidence level of each convex waveform is obtained by multiplying its energy sharpness by its echo concentration.

[0009] Optionally, based on the signal intensity distribution center on the waveform of each true echo, the true return time corresponding to each true echo is determined, including: The center of the signal intensity distribution on the waveform of each real echo is determined as the initial return time corresponding to each real echo; Based on the waveform morphology characteristics of each real echo, the initial return time corresponding to each real echo is corrected to obtain the real return time corresponding to each real echo; wherein, the waveform morphology characteristics include the position ratio of the waveform peak time relative to the waveform start and end times.

[0010] Optionally, based on the waveform morphology characteristics of each true echo, the initial return time corresponding to each true echo is corrected to obtain the true return time corresponding to each true echo, including: The waveform asymmetry coefficient is obtained by calculating the ratio of the difference between the peak time of each true echo and the waveform start time to the total width of the waveform. The corresponding compensation amount is determined based on the waveform asymmetry coefficient of each real echo. The initial return time of each real echo is then corrected based on the compensation amount corresponding to each real echo, thus obtaining the real return time corresponding to each real echo.

[0011] Optionally, based on the difference between the actual return time and the laser emission time corresponding to each actual echo, the actual distance corresponding to each actual echo is calculated, including: The time of flight of the laser corresponding to each real echo is determined based on the difference between the real return time and the laser emission time corresponding to each real echo. The actual distance corresponding to each real echo is calculated by multiplying the laser flight time and the speed of light for each real echo.

[0012] In a second aspect, a pulsed laser ranging method is provided, applied to the pulsed laser rangefinder described in the first aspect, the method comprising: After emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple convex waveforms are segmented from the continuous signal according to an intensity threshold; wherein, the intensity threshold is determined by the ambient light acquired before emitting the probe laser pulse; The morphological characteristics of each convex waveform are analyzed to obtain the confidence level of each convex waveform, and multiple true echoes are obtained from multiple convex waveforms based on the confidence level. The morphological characteristics of the convex waveform include the pulse width and peak height of the convex waveform, and the confidence level characterizes the degree of correlation between the convex waveform and the target object. The true return time corresponding to each true echo is determined based on the center of the signal intensity distribution on the waveform of each true echo. The actual distance corresponding to each true echo is calculated based on the difference between the true return time and the laser emission time.

[0013] Optionally, the step of acquiring a continuous signal after emitting a detection laser pulse to the target object, and segmenting multiple convex waveforms from the continuous signal according to an intensity threshold, includes: Before emitting a detection laser pulse to the target object, multiple ambient light samples are collected, and the preset effective threshold is corrected based on the average value of the multiple ambient light intensities to obtain the intensity threshold. The theoretical flight time corresponding to the target ranging distance is combined with the preset safety margin duration to obtain the opening duration of the receiving channel; After emitting a detection laser pulse at the target object, the continuous signal is acquired during the opening time of the receiving channel; The moment when the signal strength in the continuous signal is greater than the strength threshold from bottom to top is taken as the start time of the corresponding convex waveform, and the moment when the signal strength in the continuous signal is less than the strength threshold from top to bottom is taken as the end time of the corresponding convex waveform, thus obtaining multiple convex waveforms; wherein the signal strength in the convex waveform is greater than the strength threshold.

[0014] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this application.

[0015] This application offers the following advantages: The receiving module pre-collects ambient light to determine the intensity threshold before laser emission and collects continuous signals throughout the entire echo period after laser emission, overcoming the defect of premature closure of the receiving window due to premature triggering by water mist, smoke, etc., effectively avoiding frequent false alarms. The analysis module analyzes the morphological characteristics such as pulse width and peak height of each raised waveform, calculates the confidence level characterizing the correlation between the raised waveform and the target object, and filters out the true echoes based on the confidence level. This accurately distinguishes hard targets such as metal workpieces from interference objects such as water mist and smoke, significantly improving measurement reliability in complex industrial environments. The determination module determines the true return time based on the signal intensity distribution center on the true echo waveform, exhibiting stronger anti-interference capability against waveform edge distortion and ensuring ranging accuracy. The calculation module independently calculates the actual distance for each true echo, outputting the distance to a single target or the distance information of multiple targets or multiple reflecting interfaces simultaneously. In complex industrial environments such as welding fumes and cutting fluid water mist, this significantly improves the measurement stability and ranging accuracy of the pulsed laser rangefinder. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a pulsed laser rangefinder in one embodiment; Figure 2 This is a flowchart of a pulsed laser ranging method in one embodiment; Figure 3 This is a schematic diagram of the structure of an electronic device in one embodiment. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a pulsed laser rangefinder and its laser ranging method according to this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] The specific scheme of a pulsed laser rangefinder provided in this application is described below with reference to the accompanying drawings. Figure 1 As shown, the rangefinder includes: The receiving module 11 is used to acquire a continuous signal after emitting a detection laser pulse to the target object, and to segment multiple raised waveforms from the continuous signal according to an intensity threshold.

[0021] The intensity threshold is determined by the ambient light collected before the detection laser pulse is emitted.

[0022] The hardware configuration of the pulse rangefinder provided in this application embodiment includes: ① High-frequency beam emission link: This includes a master clock generator, a high-speed, high-current drive circuit, and a laser diode (LD) or a vertical-cavity surface-emitting laser (VCSEL). Triggered by the master clock, it emits an extremely narrow, high-energy probe beam with a pulse width in the nanosecond range (e.g., 2-5 ns) towards the target region. ② Photoelectric avalanche receiving link: This includes a receiving optical lens group, an avalanche photodiode (APD) or a single-photon avalanche diode array (SPAD / SiPM), and a high-bandwidth transimpedance preamplifier (TIA). Its function is to capture the weak photons reflected sequentially from water mist, glass, and finally the hard target, and to convert them into a continuous analog micro-current using the photoelectric effect and avalanche gain. This micro-current is then converted into a continuous analog voltage signal with a certain voltage amplitude by the transimpedance amplifier. ③ Central Processing Core: Employs a microprocessor (such as an FPGA) with high-speed computing capabilities to carry out and execute logical operations.

[0023] It also includes a high-speed analog-to-digital converter (ADC), which acquires data at a sampling rate of 1 GSps based on a high-speed ADC synchronized with the master clock. The moment the laser is emitted from the transmitting link, the master clock synchronously sends a start command to the data acquisition module. The high-speed ADC immediately begins high-frequency slicing of the continuous analog voltage signal output from the receiving link, and each discrete voltage value generated by the high-speed ADC slice is stored in its internal memory.

[0024] In one embodiment, after emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple raised waveforms are segmented from the continuous signal according to an intensity threshold, including: Before emitting a detection laser pulse to the target object, multiple ambient light samples are collected, and the preset effective threshold is corrected based on the average value of the multiple ambient light intensities to obtain the intensity threshold. The theoretical flight time corresponding to the target ranging distance is combined with the preset safety margin duration to obtain the opening duration of the receiving channel; After emitting a detection laser pulse at the target object, the continuous signal is acquired during the opening time of the receiving channel; The moment when the signal strength in the continuous signal is greater than the strength threshold from bottom to top is taken as the start time of the corresponding convex waveform, and the moment when the signal strength in the continuous signal is less than the strength threshold from top to bottom is taken as the end time of the corresponding convex waveform, thus obtaining multiple convex waveforms; wherein the signal strength in the convex waveform is greater than the strength threshold.

[0025] The target object can be one or multiple.

[0026] In heavy-duty welding workshops, in addition to metal fumes, there are also intense flashes from arc welding. This stray light enters the rangefinder lens, causing the receiver's base voltage (noise floor) to fluctuate continuously. If the effective threshold for judging the echo remains constant, when the background light suddenly brightens, the system will mistakenly identify the background light as reflection from an obstacle, leading the rangefinder to believe that abnormal noise such as welding flashes is reflected laser light. Therefore, it is necessary to determine the echo intensity threshold.

[0027] Before each official laser pulse is emitted, for a short period (e.g., 5 microseconds), the rangefinder keeps the laser off and turns on the receiver in advance. During this time, all light level fluctuations received by the receiver originate entirely from the ambient light and the noise floor from the device's own circuitry. The main control chip quickly analyzes the received signal and calculates the stray light intensity in the current environment (represented by voltage values ​​in photoelectric detection). The intensity threshold for the current environment is then determined. The calculation formula is: ; in, The preset effective threshold can be used to measure the system noise floor under dark room conditions without ambient light interference. The preset effective threshold is set to a value slightly higher than the noise floor. The number of times ambient light is collected. For the m-th ambient light sampling, Let be the intensity of the ambient light during the m-th sampling.

[0028] Because existing pulsed lasers stop receiving signals after emitting the laser and detecting a suspected target, detecting interference such as water mist can lead to significant deviations in distance measurement. Therefore, it is necessary to determine the on-time of the rangefinder's receiving channel. The calculation formula is: ; in, The target ranging distance can be understood as the farthest distance that the rangefinder needs to measure in the current environment. The speed of light can be understood as the constant speed at which a laser beam travels through the air. The preset safety margin duration is used to ensure that even the most distant signals can be fully recorded in high-temperature or high-humidity industrial environments where electronic components may experience extremely slight delays in response. The safety margin duration can be customized to suit specific needs. Characterizes the theoretical flight time required for a laser to travel to and from the target at the ranging distance.

[0029] After emitting a detection laser pulse at the target object, the receiver is activated for the specified duration, and continuous signals are acquired within that duration. The continuous signals are iterated over, and when the signal strength is detected to cross an intensity threshold from bottom to top, that moment is taken as the start time of the corresponding spike waveform. The system then continues searching along the time axis. When it detects that the signal strength has dropped below the strength threshold again, it takes that moment as the termination point of the corresponding spike waveform. , start time and termination time Extract all signal strength and time data segments contained within the signal to obtain a bulge waveform. Repeat the above process until the entire continuous signal has been traversed, resulting in multiple bulge waveforms.

[0030] Analysis module 12 is used to analyze the morphological characteristics of each convex waveform, obtain the confidence level of each convex waveform, and select multiple real echoes from multiple convex waveforms based on the confidence level.

[0031] Among them, the morphological characteristics of the convex waveform include the pulse width and peak height of the convex waveform. The confidence level characterizes the degree of correlation between the convex waveform and the target object. The higher the confidence level, the more likely the convex waveform is to come from the real target object.

[0032] When the probe laser pulse passes through the cutting fluid mist, which is a semi-transparent fluid without a fixed structure, photons are reflected back sequentially within a relatively thick space. Therefore, the received echo waveform looks like a short, stout mound. However, when the probe laser pulse passes through the mist and finally impacts a hard, flat metal workpiece, a large number of photons are violently bounced back at the same instant. In this case, the received echo waveform looks like a steep, sharp spike. Therefore, it is necessary to analyze the morphological characteristics of the received convex waveform.

[0033] In one embodiment, the morphological characteristics of each convex waveform are analyzed to obtain the confidence level of each convex waveform, and multiple true echoes are obtained from multiple convex waveforms based on the confidence level, including: The echo concentration of each convex waveform is calculated based on the degree of negative correlation between the pulse width of each convex waveform and its energy distribution. The confidence level of each convex waveform is obtained by fusing its energy sharpness with its echo concentration. The energy sharpness of each convex waveform characterizes the sharpness of the signal intensity within the convex waveform, and is obtained by analyzing the peak height and pulse width of each convex waveform. A bulge waveform with a confidence level greater than a preset confidence threshold is identified as a true echo.

[0034] Specifically, based on the correlation between the pulse width of each convex waveform and its energy distribution, the echo concentration of each convex waveform is calculated, including: The difference between the signal strength and the strength threshold at each moment within each convex waveform is accumulated to obtain the energy accumulation value of each convex waveform; The echo concentration of each convex waveform is obtained by calculating the ratio of the cumulative energy value within each convex waveform to the square of its pulse width; the echo concentration characterizes the degree of energy concentration of the convex waveform.

[0035] The preset confidence threshold can be set according to the actual situation, for example, 0.6.

[0036] For the r-th convex waveform, calculate the echo concentration of the convex waveform. The echo concentration characterizes the degree of energy concentration of the convex waveform. The calculation formula is: ; in, Let r be the termination time of the r-th convex waveform. Let r be the starting time of the r-th convex waveform. This is a local minimum value, which can be 0.001. Let be the signal strength of the r-th bulge waveform at time t. The intensity threshold, For normalization function, The smaller the value, the smaller the pulse width of the convex waveform (the more concentrated the signal reflection), and the higher the energy accumulation value. The larger the value, the larger the cumulative energy area of ​​the convex waveform, which in turn indicates that the smaller the pulse width and the stronger the energy, and the higher the echo concentration of the waveform signal of the r-th convex.

[0037] Regarding the normalization function The specific operation can be performed as follows: Receive the previously calculated unnormalized feature value as input, and obtain the original feature calculation result of the unnormalized echo concentration of a certain convex waveform signal, that is... The calculation results are used to simultaneously read the theoretical absolute maximum reference value of the unnormalized echo concentration under full-scale reflection conditions, which is stored in the microprocessor before the system leaves the factory. The larger the theoretical absolute maximum reference value, the wider the range of signal fluctuations the system can accommodate. Based on the above calculation results of the original characteristics of the unnormalized echo concentration and the corresponding theoretical absolute maximum reference value, a division operator is used to divide the extracted calculation results of the original characteristics of the unnormalized echo concentration by the corresponding theoretical absolute maximum reference value. Through this proportional operation based on a unified external scale, the mapping of absolute magnitudes is completed. Finally, a dimensionless proportional value distributed between 0 and 1 is output.

[0038] In one embodiment, the energy sharpness of each bulge waveform is fused with its echo concentration to obtain the confidence level of each bulge waveform, including: Calculate the ratio of the peak height to the pulse width within each bulge waveform to obtain the energy sharpness of each bulge waveform; The confidence level of each convex waveform is obtained by multiplying its energy sharpness by its echo concentration.

[0039] Because hard objects such as metal workpieces bounce rapidly upon encountering a laser, generating high spikes, after calculating the echo concentration of each spike waveform, it is necessary to analyze the relationship between the pulse width and the spike height of each spike waveform to determine the overall confidence level of the r-th spike waveform. The confidence level of the r-th spike waveform. The calculation formula is: ; in, For normalization function, The peak height (maximum voltage value) of the r-th bulge waveform. The energy sharpness of the convex waveform is the value of the energy sharpness. The higher the value of the energy sharpness, the greater the hardness index of the detected object, which means that it is more likely to be the target object.

[0040] Regarding the normalization function The specific operation can be performed as follows: Receive the previously calculated unnormalized confidence feature values ​​as input (i.e., The calculation results are read, and the theoretical absolute maximum reference value corresponding to the unnormalized confidence level under the full-scale reflection state of the device is read from the microprocessor stored by the system before leaving the factory. Using the division operator, the original feature calculation result of the currently extracted unnormalized confidence level is divided by the corresponding theoretical absolute maximum reference value to complete the mapping process of the absolute magnitude and output a dimensionless scale value distributed between 0 and 1.

[0041] The confidence levels of multiple raised waveforms are calculated. Waveforms with a confidence level greater than 0.6 are identified as true echoes, resulting in H true echoes. The remaining raised waveforms are identified as interference echoes. Filtering true echoes based on confidence levels effectively distinguishes echoes from real target objects from interference echoes from semi-transparent media such as water mist and smoke, thereby eliminating false alarm signals and improving the measurement reliability of pulsed laser rangefinders in complex industrial environments.

[0042] The determination module 13 is used to determine the true return time corresponding to each true echo based on the signal intensity distribution center on the waveform of each true echo.

[0043] After eliminating raised echoes caused by abnormal noise interference such as water mist, the true echo from the target object, such as a metal workpiece, can be obtained. When water mist or abnormal noise interference is present, the probe laser pulse will be scattered and distorted after penetrating dense water mist or smoke, which may cause irregular fluctuations in the leading edge of the returned true echo. If the laser flight time is calculated by finding the start time of the true waveform using traditional methods, it may produce a large distance error. Therefore, it is necessary to determine the true laser flight time of each true echo.

[0044] In one embodiment, determining the true return time corresponding to each true echo based on the signal intensity distribution center on the waveform of each true echo includes: The center of the signal intensity distribution on the waveform of each real echo is determined as the initial return time corresponding to each real echo; Based on the waveform morphology characteristics of each real echo, the initial return time corresponding to each real echo is corrected to obtain the real return time corresponding to each real echo; wherein, the waveform morphology characteristics include the position ratio of the waveform peak time relative to the waveform start and end times.

[0045] For the h-th real echo, since its waveform leading edge exhibits irregular fluctuations, it is necessary to determine the core signal intensity distribution center on the waveform of the h-th real echo as the initial return time corresponding to the real echo. This is equivalent to finding the equilibrium point of an irregular object; no matter how severely the waveform edges are eroded by smoke, its core centroid containing the highest photon energy remains relatively stable. The initial return time corresponding to the h-th real echo. The calculation formula is: ; in, Let t be the time t. It can be understood that t is the time t in each waveform. When the waveform is a convex waveform, t is the time t in the r-th convex waveform. When the waveform is a true echo, t is the time t in the h-th true echo. Let h be the termination time of the h-th true echo. Let h be the start time of the h-th true echo. Let be the signal strength at time t in the h-th real echo. This can be understood as treating the real echo as a quality distribution, finding an equilibrium point on the time axis, and determining the center of the signal intensity distribution found as the corresponding initial return time.

[0046] Specifically, based on the waveform characteristics of each true echo, the initial return time corresponding to each true echo is corrected to obtain the true return time corresponding to each true echo, including: The waveform asymmetry coefficient is obtained by calculating the ratio of the difference between the peak time of each true echo and the waveform start time to the total width of the waveform. The corresponding compensation amount is determined based on the waveform asymmetry coefficient of each real echo. The initial return time of each real echo is then corrected based on the compensation amount corresponding to each real echo, thus obtaining the real return time corresponding to each real echo.

[0047] For the h-th real echo, when the laser pulse passes through a medium such as water mist or smoke, the forward scattering effect will cause the leading edge of the echo waveform to broaden, causing the energy center of the waveform to shift forward relative to the real return time. The more the peak time is biased to the left of the waveform, the more severe the waveform tailing and the more the energy center of gravity shifts forward. Therefore, a compensation term needs to be set according to the degree of leftward shift of the peak to correct the initial return time backward.

[0048] The true return time corresponding to the h-th true echo The calculation formula is: ; in, Let h be the waveform asymmetry coefficient of the h-th real echo. , To ensure the value is extremely small, to prevent the denominator from being 0. Let h be the peak time of the h-th true echo. Let h be the start time of the h-th true echo. This is the termination time of the h-th real echo. The value range is from 0 to 1, when When =0.5, the waveform is symmetrical. When <0.5, the peak value is shifted to the left. When the value is greater than 0.5, the peak value is biased to the right. The preset compensation intensity coefficient, having a time dimension, is pre-calibrated based on the rangefinder's sampling rate and the waveform broadening under typical water mist conditions. It should be noted that when... When <0.5, the compensation amount If positive, adjust the initial return time backward; when When the value is greater than 0.5, the compensation is negative, and the initial return time is corrected forward; when... When the value is 0.5, the compensation amount is zero.

[0049] The calculation module 14 is used to calculate the actual distance corresponding to each real echo based on the difference between the real return time and the laser emission time corresponding to each real echo.

[0050] In one embodiment, the actual distance corresponding to each true echo is calculated based on the difference between the true return time and the laser emission time for each true echo, including: The time of flight of the laser corresponding to each real echo is determined based on the difference between the real return time and the laser emission time corresponding to each real echo. The actual distance corresponding to each real echo is calculated by multiplying the laser flight time and the speed of light for each real echo.

[0051] Laser emission time is Then the first The laser flight time corresponding to each real echo The calculation formula is: The actual distance corresponding to each real echo is calculated based on the product of the laser's time of flight and the speed of light. Specifically, the... The actual distance corresponding to each true echo The calculation formula is: ,in For the speed of light, multiplied by This is because the laser's flight distance includes the round trip.

[0052] Using the above method, for the selected Each real echo is used to calculate its corresponding actual distance, thereby enabling distance measurement of at least one target object or at least one reflective interface. It should be noted that each real echo can correspond to different reflective interfaces of the same target object (e.g., the front and back surfaces of glass), or it can correspond to different target objects (e.g., a nearby shelf leg and a distant wall). In either case, each real echo independently calculates its corresponding actual distance, thus providing richer environmental perception information.

[0053] The rangefinder embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs.

[0054] This application also provides a pulsed laser ranging method, such as... Figure 2 As shown, the method includes: S21. After emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple raised waveforms are segmented from the continuous signal according to an intensity threshold; wherein, the intensity threshold is determined by the ambient light acquired before emitting the probe laser pulse; S22. Analyze the morphological characteristics of each convex waveform to obtain the confidence level of each convex waveform, and select multiple true echoes from multiple convex waveforms based on the confidence level; wherein, the morphological characteristics of the convex waveform include the pulse width and peak height of the convex waveform, and the confidence level characterizes the degree of correlation between the convex waveform and the target object. S23. Determine the true return time corresponding to each true echo based on the signal intensity distribution center on the waveform of each true echo; S24. Calculate the actual distance corresponding to each real echo based on the difference between the real return time and the laser emission time corresponding to each real echo.

[0055] In one embodiment, after emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple raised waveforms are segmented from the continuous signal according to an intensity threshold, including: Before emitting a detection laser pulse to the target object, multiple ambient light samples are collected, and the preset effective threshold is corrected based on the average value of the multiple ambient light intensities to obtain the intensity threshold. The theoretical flight time corresponding to the target ranging distance is combined with the preset safety margin duration to obtain the opening duration of the receiving channel; After emitting a detection laser pulse at the target object, the continuous signal is acquired during the opening time of the receiving channel; The moment when the signal strength in the continuous signal is greater than the strength threshold from bottom to top is taken as the start time of the corresponding convex waveform, and the moment when the signal strength in the continuous signal is less than the strength threshold from top to bottom is taken as the end time of the corresponding convex waveform, thus obtaining multiple convex waveforms; wherein the signal strength in the convex waveform is greater than the strength threshold.

[0056] As the method embodiment is basically corresponding to the rangefinder embodiment, the relevant parts can be referred to in the description of the rangefinder embodiment.

[0057] It should be understood that, although Figure 2 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 2 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0058] Figure 3 This is a schematic diagram of the structure of an electronic device according to an example embodiment of this application. The electronic device includes a memory, a processor, and a computer program stored in the memory and used to run on the processor. When the processor executes the computer program, it implements the method described in any of the above embodiments. Figure 3 The electronic device 30 shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0059] like Figure 3As shown, the electronic device 30 can be manifested as a general-purpose computing device, such as a server device. The components of the electronic device 30 may include, but are not limited to: at least one processor 31, at least one memory 32, and a bus 33 connecting different system components (including memory 32 and processor 31).

[0060] Bus 33 includes a data bus, an address bus, and a control bus.

[0061] The memory 32 may include volatile memory, such as random access memory 321 and / or cache memory 322, and may further include read-only memory 323.

[0062] The memory 32 may also include a program tool 325 (or utility) having a set (at least one) program module 324, such program module 324 including but not limited to: an operating system, one or more application programs, other program modules and program data, each or some combination of these examples may include an implementation of a network environment.

[0063] The processor 31 executes various functional applications and data processing, such as the methods provided in any of the above embodiments, by running computer programs stored in the memory 32.

[0064] Electronic device 30 can also communicate with one or more external devices 34 (e.g., keyboard, pointing device, etc.). This communication can be made through input / output interface 35. Furthermore, electronic device 30 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public network, such as the Internet) via network adapter 36. As shown, network adapter 36 communicates with other modules of electronic device 30 via bus 33. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with electronic device 30, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0065] It should be noted that although several units / modules or sub-units / modules of the electronic device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0066] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method provided in any of the above embodiments.

[0067] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0068] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0069] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method described in any of the above embodiments.

[0070] The program code for executing the computer program product of this application can be written in any combination of one or more programming languages. The program code can be executed entirely on the user device, partially on the user device, as a standalone software package, partially on the user device and partially on a remote device, or entirely on a remote device.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0072] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.

[0073] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A pulsed laser rangefinder, characterized in that, The rangefinder includes: The receiving module is used to acquire a continuous signal after emitting a probe laser pulse at the target object, and to segment multiple raised waveforms from the continuous signal according to an intensity threshold; wherein the intensity threshold is determined by the ambient light acquired before emitting the probe laser pulse. The analysis module is used to analyze the morphological characteristics of each convex waveform, obtain the confidence level of each convex waveform, and filter out multiple true echoes from multiple convex waveforms based on the confidence level. The morphological characteristics of the convex waveform include the pulse width and peak height of the convex waveform, and the confidence level represents the degree of correlation between the convex waveform and the target object. The determination module is used to determine the true return time corresponding to each true echo based on the signal intensity distribution center on the waveform of each true echo; The calculation module is used to calculate the actual distance corresponding to each real echo based on the difference between the real return time and the laser emission time corresponding to each real echo.

2. The pulsed laser rangefinder as described in claim 1, characterized in that, After emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple convex waveforms are segmented from the continuous signal according to an intensity threshold, including: Before emitting a detection laser pulse to the target object, multiple ambient light samples are collected, and the preset effective threshold is corrected based on the average value of the multiple ambient light intensities to obtain the intensity threshold. The theoretical flight time corresponding to the target ranging distance is combined with the preset safety margin duration to obtain the opening duration of the receiving channel; After emitting a detection laser pulse at the target object, the continuous signal is acquired during the opening time of the receiving channel; The moment when the signal strength in the continuous signal is greater than the strength threshold from bottom to top is taken as the start time of the corresponding convex waveform, and the moment when the signal strength in the continuous signal is less than the strength threshold from top to bottom is taken as the end time of the corresponding convex waveform, thus obtaining multiple convex waveforms; wherein the signal strength in the convex waveform is greater than the strength threshold.

3. The pulsed laser rangefinder as described in claim 1, characterized in that, The morphological characteristics of each convex waveform are analyzed to obtain the confidence level of each convex waveform. Based on the confidence level, multiple true echoes are obtained from multiple convex waveforms, including: The echo concentration of each convex waveform is calculated based on the degree of negative correlation between the pulse width of each convex waveform and its energy distribution. The confidence level of each convex waveform is obtained by fusing its energy sharpness with its echo concentration. The energy sharpness of each convex waveform characterizes the sharpness of the signal intensity within the convex waveform, and is obtained by analyzing the peak height and pulse width of each convex waveform. A bulge waveform with a confidence level greater than a preset confidence threshold is identified as a true echo.

4. A pulsed laser rangefinder as described in claim 3, characterized in that, Based on the correlation between the pulse width and energy distribution of each convex waveform, the echo concentration of each convex waveform is calculated, including: The difference between the signal strength and the strength threshold at each moment within each convex waveform is accumulated to obtain the energy accumulation value of each convex waveform; The echo concentration of each convex waveform is obtained by calculating the ratio of the cumulative energy value within each convex waveform to the square of its pulse width; the echo concentration characterizes the degree of energy concentration of the convex waveform.

5. A pulsed laser rangefinder as described in claim 3, characterized in that, The energy sharpness of each bulge waveform is fused with its echo concentration to obtain the confidence level of each bulge waveform, including: Calculate the ratio of the peak height to the pulse width within each bulge waveform to obtain the energy sharpness of each bulge waveform; The confidence level of each convex waveform is obtained by multiplying its energy sharpness by its echo concentration.

6. A pulsed laser rangefinder as described in claim 1, characterized in that, Based on the signal intensity distribution center on the waveform of each true echo, determine the true return time corresponding to each true echo, including: The center of the signal intensity distribution on the waveform of each real echo is determined as the initial return time corresponding to each real echo; Based on the waveform morphology characteristics of each real echo, the initial return time corresponding to each real echo is corrected to obtain the real return time corresponding to each real echo; wherein, the waveform morphology characteristics include the position ratio of the waveform peak time relative to the waveform start and end times.

7. A pulsed laser rangefinder as described in claim 6, characterized in that, Based on the waveform characteristics of each true echo, the initial return time corresponding to each true echo is corrected to obtain the true return time corresponding to each true echo, including: The waveform asymmetry coefficient is obtained by calculating the ratio of the difference between the peak time of each true echo and the waveform start time to the total width of the waveform. The corresponding compensation amount is determined based on the waveform asymmetry coefficient of each real echo. The initial return time of each real echo is then corrected based on the compensation amount corresponding to each real echo, thus obtaining the real return time corresponding to each real echo.

8. A pulsed laser rangefinder as described in claim 1, characterized in that, Based on the difference between the actual return time and the laser emission time corresponding to each actual echo, the actual distance corresponding to each actual echo is calculated, including: The time of flight of the laser corresponding to each real echo is determined based on the difference between the real return time and the laser emission time corresponding to each real echo. The actual distance corresponding to each real echo is calculated by multiplying the laser flight time and the speed of light for each real echo.

9. A pulsed laser ranging method, characterized in that, The method is applied to a pulsed laser rangefinder according to any one of claims 1-8, and the method includes: After emitting a probe laser pulse at the target object, a continuous signal is acquired, and multiple convex waveforms are segmented from the continuous signal according to an intensity threshold; wherein, the intensity threshold is determined by the ambient light acquired before emitting the probe laser pulse; The morphological characteristics of each convex waveform are analyzed to obtain the confidence level of each convex waveform, and multiple true echoes are obtained from multiple convex waveforms based on the confidence level. The morphological characteristics of the convex waveform include the pulse width and peak height of the convex waveform, and the confidence level characterizes the degree of correlation between the convex waveform and the target object. The true return time corresponding to each true echo is determined based on the center of the signal intensity distribution on the waveform of each true echo. The actual distance corresponding to each true echo is calculated based on the difference between the true return time and the laser emission time.

10. The pulsed laser ranging method as described in claim 9, characterized in that, The process of acquiring a continuous signal after emitting a detection laser pulse at the target object, and segmenting multiple convex waveforms from the continuous signal according to an intensity threshold, includes: Before emitting a detection laser pulse to the target object, multiple ambient light samples are collected, and the preset effective threshold is corrected based on the average value of the multiple ambient light intensities to obtain the intensity threshold. The theoretical flight time corresponding to the target ranging distance is combined with the preset safety margin duration to obtain the opening duration of the receiving channel; After emitting a detection laser pulse at the target object, the continuous signal is acquired during the opening time of the receiving channel; The moment when the signal strength in the continuous signal is greater than the strength threshold from bottom to top is taken as the start time of the corresponding convex waveform, and the moment when the signal strength in the continuous signal is less than the strength threshold from top to bottom is taken as the end time of the corresponding convex waveform, thus obtaining multiple convex waveforms; wherein the signal strength in the convex waveform is greater than the strength threshold.

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