Laser ranging signal processing device, laser ranging equipment and corresponding method

Abstract

The present application provides a laser ranging and a corresponding signal processing scheme, wherein a dual-path comparison acquisition module processes a second electrical signal in two paths, compares the signals with a low-level threshold and a high-level threshold, respectively, determines a first time value, a second time value, a third time value, and a fourth time value, and then a signal calibration module determines the signal category according to the first time value, the second time value, the third time value, and the fourth time value, and calibrates the laser pulse flight time in a corresponding manner according to the signal category. Since a dual-path comparison acquisition module is used to process the electrical signal in two paths respectively, and two time values ​​are collected based on the low-level threshold and the high-level threshold, two-dimensional information of the signal can be obtained, the geometric features of the signal waveform can be effectively restored, and the laser pulse flight time can be calibrated to improve the accuracy of ranging, and by classifying and processing the signal, the detection rate of complex scenes is improved and the possibility of false detection is reduced.

Description

Technical Field

[0001] The present application relates to the field of laser ranging technology, and in particular to a laser ranging signal processing device, a laser ranging equipment and a corresponding method thereof. Background Art

[0002] As a high-precision ranging solution, laser ranging technology has attracted more and more attention from engineers due to its long ranging limit, high beam directivity and fast response speed.

[0003] There are three main types of technical means currently used in laser ranging, including (1) similar triangulation principle, which projects the ranging range onto the receiving plane according to the similar triangle relationship, and infers the distance of the object to be measured based on the position of the receiving light spot projected onto the receiving plane; (2) phase interferometry, which infers the phase of the interference light by collecting the coherence effect, and then obtains the distance of the object to be measured; (3) pulse laser time of flight (TOF) method, which measures the distance by collecting the laser pulse flight time. Among these measurement principles, the similar triangulation principle cannot guarantee the measurement accuracy of long distances, and the measurement frequency is low; and the phase interferometry method also has the problems of slow measurement speed and high cost. Therefore, the main long-distance measurement method currently used is still the pulse laser time of flight method.

[0004] The existing pulse laser time-of-flight method generally uses only a single comparator and a single time collector to compare the threshold and collect time. Therefore, the geometric characteristics of the reflected light signal cannot be truly restored, and the signal calibration module can only process according to the collected time data, so it cannot identify whether the collected signal is the real signal wave of the reflected light of the measured object, and cannot effectively reflect the real waveform, resulting in the inability to accurately calibrate the value of the laser pulse flight time, especially the recognition of transparent objects is poor, which is easy to cause false detection. Summary of the invention

[0005] An object of the present application is to provide a laser ranging signal processing device, a laser ranging device and a corresponding method thereof, so as to solve the problem of insufficient accuracy and easy misdetection in the prior art.

[0006] To achieve the above object, the present application provides a laser ranging signal processing device, the device comprising:

[0007] A photoelectric conversion module, used for converting the received laser signal into a first electrical signal;

[0008] an amplification module, connected to the photoelectric conversion module, configured to amplify the first electrical signal and output a second electrical signal;

[0009] A dual-path comparison acquisition module, connected to the amplification module, for comparing the second electrical signal with the low level threshold and the high level threshold respectively, and determining a first time value, a second time value, a third time value and a fourth time value, wherein the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold;

[0010] The signal calibration module is used to determine the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrate the laser pulse flight time in a corresponding manner according to the signal category.

[0011] The present application also provides a laser ranging device, which includes the aforementioned laser ranging signal processing device and a calculation module, wherein the laser ranging signal processing device is used to obtain the laser pulse flight time, and the calculation module is used to calculate the distance value according to the laser pulse flight time.

[0012] Based on another aspect of the present application, a laser ranging signal processing method is also provided, the method comprising:

[0013] Converting the received laser signal into a first electrical signal;

[0014] amplifying the first electrical signal and outputting a second electrical signal;

[0015] Compare the second electrical signal with the low level threshold and the high level threshold respectively, and determine a first time value, a second time value, a third time value, and a fourth time value, wherein the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold;

[0016] The signal category is determined according to the first time value, the second time value, the third time value and the fourth time value, and the laser pulse flight time is calibrated in a corresponding manner according to the signal category.

[0017] The present application also provides a laser ranging method, the method comprising:

[0018] converting the received laser signal into a first electrical signal;

[0019] amplifying the first electrical signal and outputting a second electrical signal;

[0020] Compare the second electrical signal with the low level threshold and the high level threshold respectively, and determine a first time value, a second time value, a third time value, and a fourth time value, wherein the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold;

[0021] Determine a signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrate the laser pulse flight time in a corresponding manner according to the signal category;

[0022] A distance value is calculated based on the laser pulse flight time.

[0023] Compared with the prior art, in the solution provided by the present application, the amplified second electrical signal is processed in two ways by a dual-path comparison acquisition module, and is compared with a low-level threshold and a high-level threshold respectively, to determine a first time value, a second time value, a third time value and a fourth time value, and then the signal calibration module determines the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrates the laser pulse flight time in a corresponding manner according to the signal category. Since a dual-path comparison acquisition module is used to process the electrical signal in two ways respectively, and two time values ​​are collected based on a low-level threshold and a high-level threshold respectively, the two-dimensional information of the signal can be obtained, the geometric features of the signal waveform are effectively restored, and the laser pulse flight time is calibrated to improve the accuracy of ranging, and the detection rate of complex scenes is improved and the possibility of false detection is reduced by classifying and processing the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 A schematic diagram of the structure of a laser ranging signal processing device provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of a voltage signal waveform in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of the circuit structure of a low-level comparator and a low-level time collector for collecting signals in an embodiment of the present application;

[0028] Figure 4 This is a schematic diagram of the circuit structure of a high-level comparator and a high-level time collector for collecting signals in an embodiment of the present application;

[0029] Figure 5 A waveform diagram corresponding to the second signal category in an embodiment of the present application;

[0030] Figure 6 A waveform diagram corresponding to the third signal category in an embodiment of the present application;

[0031] Figure 7 A waveform diagram corresponding to the fourth signal category in the embodiment of the present application;

[0032] Figure 8 A waveform diagram corresponding to the fifth signal category in the embodiment of the present application;

[0033] Fig. 9 A waveform diagram corresponding to the sixth signal category in an embodiment of the present application;

[0034] Fig.10 A waveform diagram corresponding to the seventh signal category in the embodiment of the present application;

[0035] Fig.11 A waveform diagram corresponding to the eighth signal category in the embodiment of the present application;

[0036] Fig.12 A waveform diagram corresponding to the ninth signal category in an embodiment of the present application;

[0037] Fig.13 A waveform diagram corresponding to the tenth signal category in the embodiment of the present application;

[0038] Fig.14 A schematic diagram of a laser distance measuring device provided in an embodiment of the present application;

[0039] The same or similar reference numerals in the drawings represent the same or similar components. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] In the laser ranging signal processing scheme provided by the present application, the amplified second electrical signal is processed in two ways by a dual-path comparison acquisition module, and is compared with a low-level threshold and a high-level threshold respectively to determine a first time value, a second time value, a third time value and a fourth time value, and then the signal calibration module determines the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrates the laser pulse flight time in a corresponding manner according to the signal category. Since the dual-path comparison acquisition module is used to process the electrical signal in two ways respectively, and two time values ​​are collected based on the low-level threshold and the high-level threshold respectively, the two-dimensional information of the signal can be obtained, the geometric features of the signal waveform can be effectively restored, and the laser pulse flight time can be calibrated to improve the accuracy of ranging, and the detection rate of complex scenes can be improved and the possibility of false detection can be reduced by classifying and processing the signal.

[0042] Figure 1 The schematic diagram of the structure of a laser ranging signal processing device provided by an embodiment of the present application is shown, which at least includes a photoelectric conversion module 110, an amplification module 120, a dual-path comparison acquisition module 130 and a signal calibration module 140. The photoelectric conversion module 110 is used to convert the received laser signal into a first electrical signal; the amplification module 120 is connected to the photoelectric conversion module, and is used to amplify the first electrical signal and output a second electrical signal; the dual-path comparison acquisition module 130 is connected to the amplification module, and is used to compare the second electrical signal with a low level threshold and a high level threshold respectively, and determine a first time value, a second time value, a third time value and a fourth time value; the signal calibration module 140 is used to determine the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrate the laser pulse flight time in a corresponding manner according to the signal category.

[0043] In some embodiments of the present application, the photoelectric conversion module 110 may include a photosensitive module and a voltage-current conversion module, wherein the photosensitive module may receive a laser signal reflected by the object under test, generate photogenerated carriers, and convert the light signal into a current signal, and the voltage-current conversion module may convert the current signal into a voltage signal for subsequent modules to process the voltage signal. It can be seen that in the solution of this embodiment, the first electrical signal is the voltage signal generated by the voltage-current conversion module.

[0044] Since the voltage signal converted from the laser signal is generally small, the error of direct subsequent processing is large, and it needs to be amplified before subsequent processing. In this embodiment, in order to improve the accuracy of amplification and reduce the possibility of signal distortion caused by amplification, a two-stage amplification method can be adopted. Therefore, the amplification module 120 may include a signal pre-amplification module and a signal post-stage amplification module, wherein the signal pre-amplification module can linearly amplify the voltage signal converted by the voltage-current conversion module and suppress the noise floor amplitude to a certain extent, and the signal post-stage amplification module will further amplify the voltage signal after preliminary amplification for subsequent modules to process. It can be seen that in the scheme of this embodiment, the second electrical signal is the voltage signal generated after amplification by the amplification module.

[0045] The dual-channel comparison acquisition module adopts a two-channel comparison acquisition circuit, and each channel is set with different comparison thresholds, which are low-level thresholds and high-level thresholds, respectively, and the low-level threshold is numerically lower than the high-level threshold. The first time value, the second time value, the third time value and the fourth time value determined by the dual-channel comparison acquisition module are time values ​​determined based on the comparison thresholds set respectively, wherein the first time value and the fourth time value are determined by one comparison acquisition module based on the low-level threshold, and the second time value and the third time value are determined by the other comparison acquisition module based on the high-level threshold.

[0046] Specifically, the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold. Figure 2 As an example, the voltage signal waveform shown in the figure, the x-axis represents time t, and the y-axis represents the voltage amplitude V of the voltage signal, V low_threshold Indicates the low level threshold, V high_threshold Represents a high level threshold, from which it can be determined that t1 is the first time value, t2 is the second time value, t3 is the third time value, and t4 is the fourth time value.

[0047] In some embodiments of the present application, the dual-channel comparison acquisition module 130 can be divided into two parts, namely, a dual-channel comparison module and a dual-channel time acquisition module. Among them, the dual-channel comparison module can include a low-level comparator and a high-level comparator, which are respectively connected to the amplification module, and the low-level comparator is used to compare the second electrical signal with the low-level threshold, intercept the third electrical signal exceeding the low-level threshold, and determine the first acquisition time point and the fourth acquisition time point according to the third electrical signal. The high-level comparator is used to compare the second electrical signal with the high-level threshold, intercept the fourth electrical signal exceeding the high-level threshold, and determine the second acquisition time point and the third acquisition time point according to the fourth electrical signal. The first acquisition time point is the starting time of the first rising edge of the third electrical signal, the second acquisition time point is the starting time of the first rising edge of the fourth electrical signal, the third acquisition time point is the end time of the first falling edge of the fourth electrical signal, and the fourth acquisition time point is the end time of the first falling edge of the third electrical signal.

[0048] by Figure 2 As an example, the low level comparator compares the voltage signal (i.e., the second electrical signal) with the low level threshold V low_threshold Compare and intercept the voltage signal that exceeds the low level threshold V low_threshold The part of the voltage signal between point a and point d is used as the third electrical signal, and then the time corresponding to point a can be used as the first acquisition time point, and the time corresponding to point d can be used as the fourth acquisition time point, and output to the low-level time collector in the dual-channel time acquisition module. Similarly, the high-level comparator compares the voltage signal (i.e., the second electrical signal) with the high-level threshold V high_threshold Compare and intercept the voltage signal that exceeds the high level threshold V high_threshold The part, that is, the part of the voltage signal between point b and point c, is used as the fourth electrical signal. Then, the time corresponding to point b can be used as the second acquisition time point, and the time corresponding to point c can be used as the third acquisition time point, and output to the high-level time collector in the dual-channel time acquisition module.

[0049] The dual-channel time acquisition module includes a low-level time collector and a high-level time collector, which are respectively connected to the low-level comparator and the high-level comparator in the dual-channel comparison module. The low-level time collector is used to determine the first time value t1 and the fourth time value t4 according to the first acquisition time point, the fourth acquisition time point and the laser emission time.

[0050] by Figure 2Taking the scenario shown as an example, the time stop1_low corresponding to point a of the voltage signal can be compared with the time start when the laser pulse signal is emitted, thereby determining the first time value t1, and the time stop2_low corresponding to point d of the voltage signal can be compared with the laser emission time start, thereby determining the fourth time value. Similarly, the high-level time collector is used to determine the second time value t2 and the third time value t3 according to the second acquisition time point stop1_high, the third acquisition time point stop2_high and the laser emission time start.

[0051] Figure 3 The circuit structure diagram of a low-level comparator and a low-level time collector for collecting signals in an embodiment of the present application is shown. The positive input terminal 310 of the low-level comparator 131 is connected to the output terminal of the amplification module, and inputs an input signal (i.e., a second electrical signal), and the negative input terminal 320 inputs a low-level threshold value V with a lower value (compared to the high-level threshold value). low_threshold , the output terminal 330 of the low-level comparator 131 is connected to one of the input terminals 340 of the low-level time collector 133. The low-level time collector 133 can be implemented by a TDC (Time-to-Digital Converter), and the start signal (i.e., the laser emission time) inputted by the other input terminal 350 thereof can be generated by the control system, and the stop_low signal is collected from the output terminal 330 of the low-level comparator 131, and can include stop1_low corresponding to the rising edge and stop2_low corresponding to the falling edge, and the low-level time collector 133 can input the laser pulse flight time △t collected along this path by calculating △t=stop_low-start. In actual scenarios, since there are two inputs stop1_low and stop2_low, the corresponding △t values, i.e., the first time value t1 and the fourth time value t4, can be obtained.

[0052] Figure 4 The circuit structure diagram of a high-level comparator and a high-level time collector for collecting signals in an embodiment of the present application is shown. The positive input terminal 410 of the high-level comparator 132 is connected to the output terminal of the amplification module, and inputs the input signal (i.e., the second electrical signal), and the negative input terminal 420 inputs a high-level threshold value V with a higher value (compared to the low-level threshold value). high_threshold, the output terminal 430 of the high level comparator 132 is connected to one of the input terminals 440 of the high level time collector 134. The high level time collector 134 can also be implemented by a TDC (Time-to-Digital Converter), and the start signal (i.e., the laser emission time) inputted by the other input terminal 450 thereof can be generated by the control system, and the stop_high signal is collected from the output terminal 430 of the high level comparator 132, and can include stop1_high corresponding to the rising edge and stop2_high corresponding to the falling edge, and the high level time collector 134 can input the laser pulse flight time △t collected along this path by calculating △t=stop_high-start. In actual scenarios, since there are two inputs stop1_high and stop2_high, the corresponding △t values, i.e., the second time value t2 and the third time value t3, can be obtained.

[0053] When calibrating the laser pulse flight time, the signal calibration module can restore the waveform characteristics of the laser signal according to the first time value, the second time value, the third time value and the fourth time value, and classify the laser signal according to the waveform characteristics, thereby determining the signal category. For example, the slope of the rising edge or falling edge of the signal waveform, or the pulse width of the signal waveform, etc. can be calculated through the first time value, the second time value, the third time value and the fourth time value. These data can reflect the waveform characteristics of the laser signal to a certain extent, thereby classifying the laser signal in a preset manner to determine the signal category.

[0054] In actual scenarios, lasers will have different reflected waveforms after irradiating different objects to be measured. Therefore, by restoring the waveform characteristics of the reflected laser signal, different characteristics of the objects to be measured in the environment can be represented to a certain extent, such as material characteristics (such as whether it is light-transmissive, etc.), location characteristics (such as the distance from the detection point, the relative distance between different objects, etc.), etc. It can be seen that in the scheme of the embodiment of the present application, corresponding signal categories can be set in advance for some typical detection scenarios, so that after the signal category is determined, the laser pulse flight time can be calibrated in a corresponding manner for different signal types.

[0055] For example, when calibrating the laser pulse flight time, all or part of the first time value, the second time value, the third time value and the fourth time value can be selected according to different signal categories, and calculated in a reasonable manner, such as weighted calculation, averaging, taking smaller values ​​or larger values, etc., to calculate a laser pulse flight time that can more accurately reflect the actual environmental conditions corresponding to the current signal type.

[0056] Figure 2 The signal waveform shown is a simplest signal category, namely the first signal category. The first signal category corresponds to a single independent pulse signal, and the amplitude of the pulse signal is at least higher than the low-level threshold. The signal corresponding to the first signal category corresponds to a single object to be measured in the detection environment, so the reflected laser signal is a single independent pulse signal, and there is no superposition of several independent signals or multiple signals, that is, the laser pulse spot is all projected onto one object to be measured and reflected back by the object to be measured. In this case, the accuracy can be guaranteed by processing according to the normal pulse laser measurement principle, for example, taking the average of the first time value, the second time value, the third time value and the fourth time value as the adjusted laser pulse flight time.

[0057] Figure 5 A waveform corresponding to the second signal category in the embodiment of the present application is shown, and the second signal category corresponds to two independent pulse signals, and the signal amplitudes of the two are higher than the high level threshold. The environment corresponding to the second signal type is: the measurement environment corresponds to two objects to be measured in front and behind, and the distance between the two objects to be measured in front and behind is far, the laser pulse spot is partially projected onto the object to be measured in front, and part of the spot is projected onto the object to be measured in the back, and the laser pulse reflection signal projected onto the object to be measured in the back still maintains a high signal amplitude. Because in the application scenario of laser ranging, the first thing to ensure is to accurately detect the object closest to the detection device, so when this signal type is obtained, only stop1 (which may include stop1_low and stop1_high) and stop2 (which may include stop2_low and stop2_high) closest to start can be collected during calibration, and subsequent independent signals can be discarded to avoid interference with the measurement signal, that is, only the signal of the first independent waveform is considered. After the subsequent independent signals are discarded, the retained signal evolves into the aforementioned Figure 2 Simple signals in the scene can be processed in the corresponding way. In addition, this situation may also be applied to the situation where multiple subsequent pulse signals are processed at the same time. As long as the subsequent pulse signals maintain an independent relationship with the first pulse signal, they can be processed according to this logic.

[0058] Figure 6A waveform corresponding to the third signal category in the embodiment of the present application is shown, and the third signal category corresponds to two independent pulse signals, the amplitude of the first pulse signal is higher than the high level threshold, and the amplitude of the second pulse signal is lower than the high level threshold and higher than the low level threshold. The environment corresponding to the third signal type is: there are two objects to be measured in the measurement environment, and the distance between the two objects to be measured is far, and part of the laser pulse spot is projected onto the object to be measured in the front, and part of the spot is projected onto the object to be measured in the back. The amplitude of the laser pulse reflection signal projected onto the object to be measured in the back is weaker. At this time, during calibration, stop1 and stop2, which are closest to the start, can be collected separately, and the subsequent independent signals can be discarded to avoid interference with the measurement signal. Since the subsequent independent signals are discarded, the retained signal evolves into a simple signal, which is consistent with Figure 6 Similarly, this situation can also be applied to the situation of processing multiple subsequent pulse signals at the same time, as long as the subsequent pulse signals maintain an independent relationship with the first pulse signal, they can be processed according to this logic.

[0059] Figure 7 A waveform corresponding to the fourth signal category in the embodiment of the present application is shown, and the fourth signal category corresponds to two independent pulse signals, the amplitude of the first pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the second pulse signal is higher than the high level threshold. A typical sign of this situation is that the second time value t2 is greater than the fourth time value t4. The environment corresponding to the fourth signal type is: there are two objects to be measured in the front and back in the measurement environment, and the distance between the front and back objects to be measured is far, the laser pulse spot is partially projected onto the object to be measured in the front, and part of the spot is projected onto the object to be measured in the back, and the amplitude of the laser pulse reflection signal projected onto the object to be measured in the back is stronger. Among them, a typical scene is that there are other objects to be measured far behind a transparent object with a certain transparency, and another typical scene is that the proportion of the spot projected onto the front object to be measured is small. For this type of signal, one of the pulse signals can be selected for processing as needed, that is, t1 and t4, or t2 and t3 are selected. Since each pulse signal is independent, no matter which pulse signal is selected for processing, the selected signal is a simple signal, that is, it is related to the attached Figure 5 The scenarios shown are equivalent.

[0060] Figure 8A waveform corresponding to the fifth signal category in the embodiment of the present application is shown, and the fifth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is higher than the high level threshold. The environment corresponding to the fifth signal type is: the measurement environment corresponds to two objects to be measured in front and behind, and the distance between the two objects to be measured in front and behind is relatively close, the laser pulse spot is partially projected onto the object to be measured in front, and part of the spot is projected onto the object to be measured in the back, and the amplitude of the laser pulse reflection signal projected onto the objects to be measured in front and behind is relatively strong. Under this signal category, due to the existence of superposition factors, the two times collected by the low level threshold, namely t1 and t4, and the two times collected by the high level threshold, namely t2 and t3, are not a true reflection of the geometric characteristics of the laser signal waveform, especially t3 and t4 cannot accurately experience the geometric characteristics of the laser signal waveform. Therefore, for this type of signal, the laser pulse flight time can be calibrated based on the first time value t1 and the second time value t2, so as to obtain better measurement accuracy.

[0061] Fig. 9 A waveform corresponding to the sixth signal category in the embodiment of the present application is shown, and the sixth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold. The environment corresponding to the sixth signal type is: the measurement environment corresponds to two objects to be measured in front and behind, and the distance between the two objects to be measured in front and behind is relatively close, the laser pulse spot is partially projected onto the object to be measured in front, and part of the spot is projected onto the object to be measured in the back, and the amplitude of the laser pulse reflection signal projected onto the two objects to be measured in front and behind is relatively strong. Under this signal category, since the amplitude of the superimposed part of the two signals is lower than the high level threshold, the two time values ​​t2 and t3 collected by the high level threshold are still the true reflection of the waveform characteristics of the original signal of the reflected light of the object to be measured in front, and the laser pulse flight time can be calibrated by the second time value t2 and the third time value t3, so as to obtain better measurement accuracy. As for the subsequent independent pulse signal, it can be discarded and not used, and the signal can also be guaranteed to be undisturbed. Similarly, this situation can also be applied to the situation of simultaneously processing multiple subsequent pulse signals. As long as the subsequent pulse signals maintain an independent relationship with the first pulse signal, they can be processed according to this logic.

[0062] Fig.10A waveform corresponding to the seventh signal category in the embodiment of the present application is shown, and the seventh signal category corresponds to two superimposed pulse signals, the amplitude of the first pulse signal is higher than the high level threshold, the amplitude of the second pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold. The environment corresponding to the seventh signal type is: there are two objects to be measured in the front and back corresponding to the measurement environment, and the distance between the two objects to be measured is relatively close. The laser pulse spot is partially projected onto the object to be measured in the front, and part of the spot is projected onto the object to be measured in the back. The amplitude of the laser pulse reflection signal projected onto the object to be measured in the front is relatively strong. Under this signal type, since the amplitude of the superimposed part of the two signals is lower than the high level threshold, the two time values ​​t2 and t3 collected through the high level threshold are still a true reflection of the waveform characteristics of the original signal of the reflected light of the front object to be measured, which is consistent with the attached Fig. 9 The corresponding situations are equivalent. Therefore, the laser pulse flight time can be calibrated by the second time value t2 and the third time value t3, so as to obtain better measurement accuracy. Similarly, it can also be applied to the situation of processing multiple subsequent pulse signals at the same time, as long as the subsequent pulse signals maintain an independent relationship with the first pulse signal, they can be processed according to this logic.

[0063] Fig.11 A waveform corresponding to the eighth signal category in the embodiment of the present application is shown, and the eighth signal category corresponds to two superimposed pulse signals, the amplitude of the first pulse signal is lower than the high level threshold and higher than the low level threshold, the amplitude of the second pulse signal is higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold. A typical sign of this situation is t2-t1>max, where max is a pre-set value. The environment corresponding to the eighth signal type is: there are two objects to be measured in the front and back corresponding to the measurement environment, and the distance between the two objects to be measured is relatively close. The laser pulse spot is partially projected onto the object to be measured in front, and part of the spot is projected onto the object to be measured in the back. The amplitude of the laser pulse reflection signal projected onto the object to be measured in the back is relatively strong. Under this signal type, since the amplitude of the superimposed part of the two signals is lower than the high level threshold, the two time values ​​t2 and t3 collected through the high level threshold are still a true reflection of the waveform characteristics of the original signal of the reflected light of the front object to be measured, which is consistent with the attached Fig. 9 The corresponding situations are equivalent. Therefore, the laser pulse flight time can be calibrated using the second time value t2 and the third time value t3 to obtain better measurement accuracy.

[0064] Fig.12A waveform corresponding to the ninth signal category in the embodiment of the present application is shown, and the ninth signal category corresponds to two superimposed pulse signals, the amplitude of the first pulse signal is lower than the high level threshold and higher than the low level threshold, the amplitude of the second pulse signal is higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold. The environment corresponding to the ninth signal type is: the measurement environment corresponds to two objects to be measured in front and behind, and the distance between the two objects to be measured in front and behind is relatively close, the laser pulse spot is partially projected onto the object to be measured in front, and part of the spot is projected onto the object to be measured in the back, and the amplitude of the laser pulse reflection signal projected onto the two objects to be measured in front and behind is relatively weak. Since this situation generally occurs in a scene where the object to be measured is far away from the detection point, the waveform obtained at this time can be ignored, and this situation is not processed. Wait until the detection point is close to obtain a waveform with a higher amplitude before processing.

[0065] Fig.13 A waveform corresponding to the tenth signal category in the embodiment of the present application is shown, and the tenth signal category corresponds to two independent pulse signals, and the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold. The typical sign of this situation is t2=t3=0. In this embodiment, the second time value t2 and the third time value t3 are zero, indicating that these two time values ​​cannot be collected. The environment corresponding to the ninth signal type is: the measurement environment corresponds to the front and rear two measured objects, and the front and rear two measured objects are far apart. The laser pulse spot is partially projected onto the front measured object, and part of the spot is projected onto the rear measured object. The signal amplitude of the laser pulse reflection signal projected onto the front and rear two measured objects is low. Under this signal type, it is only necessary to collect stop1 and stop2, which are closest to the start, based on the low level threshold, that is, to calibrate the laser pulse flight time with the first time value t1 and the fourth time value t4, so as to obtain better measurement accuracy. For subsequent independent pulse signals, they can be discarded, and the signal can also be guaranteed to be undisturbed. Similarly, this situation can also be applied to the situation of simultaneously processing multiple subsequent pulse signals. As long as the subsequent pulse signals maintain an independent relationship with the first pulse signal, they can be processed according to this logic.

[0066] By determining the different signal types of laser signals, the laser pulse flight time can be calibrated in a corresponding manner, thereby improving the ranging accuracy and the detection rate of complex scenes, especially the detection rate of transparent objects. At the same time, irregularly placed objects in the measured scene can be accurately measured, avoiding the influence of light spots.

[0067] In addition, an embodiment of the present application also provides a laser ranging device, which includes the laser ranging signal processing device in the aforementioned embodiment and a calculation module, wherein the laser ranging signal processing device is used to obtain the laser pulse flight time using the aforementioned method, and the calculation module is used to calculate the distance value based on the laser pulse flight time.

[0068] For example, in the embodiment of the present application, the following formula may be used to calculate the measured distance value L:

[0069] L=C×△t / 2

[0070] Where C is the speed of light and △t is the flight time of the laser pulse.

[0071] Fig.14 The structure of a laser ranging device provided by an embodiment of the present application is shown, including a photosensitive module 111, a voltage-current conversion module 112, a signal pre-amplification module 121, a signal post-amplification module 122, a dual-channel comparator (including a low-level comparator 131 and a high-level comparator 133), a dual-channel time collector (including a low-level time collector 132 and a high-level time collector 134) and a signal control processing system 1400. The photosensitive module 111 and the voltage-current conversion module 112 are used to implement the function of the photoelectric conversion module 110, the signal pre-amplification module 121 and the signal post-amplification module 122 are used to implement the function of the amplification module 120, the dual-channel comparators 131, 133 and the dual-channel time collectors 132, 134 are used to implement the function of the dual-channel comparison and collection module 130, and the signal control processing system 1400 is used to implement the functions of the signal calibration module and the calculation module.

[0072] When measuring distance, the photosensitive module 111 receives the reflected light from the object to be measured and generates photogenerated carriers. The voltage-current conversion module 112 converts the current signal into a voltage signal for subsequent module amplification processing. The signal pre-amplification module 121 linearly amplifies the weak signal converted by the voltage-current conversion module 112 and suppresses the noise amplitude to a certain extent. The signal post-amplification module 122 fully amplifies the signal for subsequent circuit collection and processing. The amplified signal is truncated by the dual comparators 131 and 133 and sent to their respective docking time collectors 132 and 133. After the signal value is collected, it is transmitted to the signal control processing system 1400, and the signal control processing system 1400 converts it into an actual distance value according to the signal value processing, thereby completing a distance measurement.

[0073] In addition, based on the same inventive concept, a laser ranging signal processing method and a corresponding laser ranging method are also provided in an embodiment of the present application. The device or equipment used in the method may be the laser ranging signal processing device and the laser ranging equipment in the aforementioned embodiment, and the principle of solving the problem is similar to that of the device or equipment.

[0074] A laser ranging signal processing method provided in an embodiment of the present application includes the following processing steps:

[0075] Step 1: Convert the received laser signal into a first electrical signal.

[0076] Step 2: amplify the first electrical signal and output a second electrical signal.

[0077] Step 3: Compare the second electrical signal with the low level threshold and the high level threshold respectively to determine the first time value, the second time value, the third time value and the fourth time value.

[0078] Step 4: determine the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrate the laser pulse flight time in a corresponding manner according to the signal category.

[0079] A laser ranging method provided in an embodiment of the present application includes the following processing steps:

[0080] Step 1: Convert the received laser signal into a first electrical signal.

[0081] Step 2: amplify the first electrical signal and output a second electrical signal.

[0082] Step 3: Compare the second electrical signal with the low level threshold and the high level threshold respectively to determine the first time value, the second time value, the third time value and the fourth time value.

[0083] Step 4: determine the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrate the laser pulse flight time in a corresponding manner according to the signal category.

[0084] Step 5: Calculate the distance value according to the laser pulse flight time.

[0085] Further, when comparing the second electrical signal with the low level threshold and the high level threshold respectively to determine the first time value, the second time value, the third time value and the fourth time value, a dual-channel comparison module and a dual-channel time acquisition module can be used. Wherein, the dual-number comparison module includes a low level comparator and a high level comparator, the low level comparator can compare the second electrical signal with the low level threshold, intercept the third electrical signal exceeding the low level threshold, and determine the first acquisition time point and the fourth acquisition time point according to the third electrical signal, the high level comparator can compare the second electrical signal with the high level threshold, intercept the fourth electrical signal exceeding the high level threshold, and determine the second acquisition time point and the third acquisition time point according to the fourth electrical signal, wherein the first acquisition time point is the starting time of the first rising edge of the third electrical signal, the second acquisition time point is the starting time of the first rising edge of the fourth electrical signal, the third acquisition time point is the end time of the first falling edge of the fourth electrical signal, and the fourth acquisition time point is the end time of the first falling edge of the third electrical signal.

[0086] The dual-channel time acquisition module includes a low-level time collector and a high-level time collector, which are respectively connected to the low-level comparator and the high-level comparator in the dual-channel comparison module. The low-level time collector can determine the first time value and the fourth time value according to the first acquisition time point, the fourth acquisition time point and the laser emission time, and the high-level time collector can determine the second time value and the third time value according to the second acquisition time point, the third acquisition time point and the laser emission time.

[0087] Furthermore, when determining the signal category, the waveform characteristics of the laser signal can be restored according to the first time value, the second time value, the third time value and the fourth time value, and the laser signal can be classified according to the waveform characteristics to determine the signal category.

[0088] Furthermore, the signal category may include a first signal category, the first signal category corresponds to a single independent pulse signal, and the amplitude of the pulse signal is at least higher than a low level threshold.

[0089] Further, the signal category may include a second signal category, the second signal category corresponds to two independent pulse signals, and both signal amplitudes are higher than a high level threshold.

[0090] Further, the signal category may include a third signal category, the third signal category corresponds to two independent pulse signals, the amplitude of the former pulse signal is higher than the high level threshold, and the amplitude of the latter pulse signal is lower than the high level threshold and higher than the low level threshold.

[0091] Further, the signal category may include a fourth signal category, the fourth signal category corresponding to two independent pulse signals, the amplitude of the former pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the latter pulse signal is higher than the high level threshold.

[0092] Further, the signal category may include a fifth signal category, and the fifth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is higher than the high level threshold.

[0093] Further, the signal category may include a sixth signal category, which corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold.

[0094] Further, the signal category may include a seventh signal category, which corresponds to two superimposed pulse signals, the amplitude of the former pulse signal is higher than the high level threshold, the amplitude of the latter pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold.

[0095] Further, the signal category may include an eighth signal category, which corresponds to two superimposed pulse signals, the amplitude of the former pulse signal is lower than the high level threshold and higher than the low level threshold, the amplitude of the latter pulse signal is higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold.

[0096] Further, the signal category may include a ninth signal category, which corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold.

[0097] Further, the signal category may include a tenth signal category, the tenth signal category corresponds to two independent pulse signals, and the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold.

[0098] In summary, in the laser ranging signal processing scheme provided by the present application, the amplified second electrical signal is processed in two ways by the dual-way comparison acquisition module, and is compared with the low-level threshold and the high-level threshold respectively to determine the first time value, the second time value, the third time value and the fourth time value, and then the signal calibration module determines the signal category according to the first time value, the second time value, the third time value and the fourth time value, and calibrates the laser pulse flight time in a corresponding manner according to the signal category. Since the dual-way comparison acquisition module is used to process the electrical signal in two ways respectively, and two time values ​​are collected based on the low-level threshold and the high-level threshold respectively, the two-dimensional information of the signal can be obtained, the geometric features of the signal waveform are effectively restored, and the laser pulse flight time is calibrated to improve the accuracy of ranging, and the detection rate of complex scenes is improved by the classification processing of the signal, and the possibility of false detection is reduced. In particular, the detection rate of transparent objects is improved, and the irregularly placed objects in the measured scene can be accurately measured, avoiding the influence of the light spot.

[0099] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the present application. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in the device claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

Claims

1. A laser ranging signal processing device, characterized in that: The device includes: A photoelectric conversion module, used for converting the received laser signal into a first electrical signal; an amplification module, connected to the photoelectric conversion module, and configured to amplify the first electrical signal and output a second electrical signal; A dual-path comparison acquisition module, connected to the amplification module, for comparing the second electrical signal with the low level threshold and the high level threshold respectively, and determining a first time value, a second time value, a third time value and a fourth time value, wherein the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold; A signal calibration module, used to restore the waveform characteristics of the laser signal according to the first time value, the second time value, the third time value and the fourth time value, and classify the laser signal according to the waveform characteristics to determine the signal category, and calibrate the laser pulse flight time in a corresponding manner according to the signal category; Wherein, the signal categories include a fifth signal category, a sixth signal category, a seventh signal category and a ninth signal category, the fifth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is higher than the high level threshold; the sixth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; the seventh signal category corresponds to two superimposed pulse signals, the amplitude of the former pulse signal is higher than the high level threshold, the amplitude of the latter pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; the ninth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; The laser pulse flight time is calibrated in a corresponding manner according to the signal type, including: When the signal category is the fifth signal category, calibrating the laser pulse flight time based on the first time value and the second time value; When the signal category is the sixth signal category, calibrating the laser pulse flight time based on the second time value and the third time value; When the signal category is the seventh signal category, calibrating the laser pulse flight time based on the second time value and the third time value; When the signal category is the ninth signal category, this situation is not processed, and processing is performed after the detection point approaches and a waveform with a higher amplitude is obtained.

2. The device according to claim 1, characterized in that The dual-path comparison acquisition module comprises: A dual-path comparison module, comprising a low-level comparator and a high-level comparator, which are respectively connected to the amplification module, wherein the low-level comparator is used to compare the second electrical signal with a low-level threshold, intercept a third electrical signal exceeding the low-level threshold, and determine a first acquisition time point and a fourth acquisition time point according to the third electrical signal, and the high-level comparator is used to compare the second electrical signal with a high-level threshold, intercept a fourth electrical signal exceeding the high-level threshold, and determine a second acquisition time point and a third acquisition time point according to the fourth electrical signal, wherein the first acquisition time point is the starting time of the first rising edge of the third electrical signal, the second acquisition time point is the starting time of the first rising edge of the fourth electrical signal, the third acquisition time point is the end time of the first falling edge of the fourth electrical signal, and the fourth acquisition time point is the end time of the first falling edge of the third electrical signal; The dual-channel time acquisition module includes a low-level time collector and a high-level time collector, which are respectively connected to the low-level comparator and the high-level comparator in the dual-channel comparison module, wherein the low-level time collector is used to determine the first time value and the fourth time value according to the first acquisition time point, the fourth acquisition time point and the laser emission time, and the high-level time collector is used to determine the second time value and the third time value according to the second acquisition time point, the third acquisition time point and the laser emission time.

3. The device according to claim 1 or 2, characterized in that: The signal category includes a first signal category, the first signal category corresponds to a single independent pulse signal, and the amplitude of the pulse signal is at least higher than a low level threshold.

4. The device according to claim 1 or 2, characterized in that: The signal category includes a second signal category, the second signal category corresponds to two independent pulse signals, and both signal amplitudes are higher than a high level threshold.

5. The device according to claim 1 or 2, characterized in that: The signal category includes a third signal category, and the third signal category corresponds to two independent pulse signals, the amplitude of the first pulse signal is higher than the high level threshold, and the amplitude of the second pulse signal is lower than the high level threshold and higher than the low level threshold.

6. The device according to claim 1 or 2, characterized in that: The signal category includes a fourth signal category, and the fourth signal category corresponds to two independent pulse signals, the amplitude of the former pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the latter pulse signal is higher than the high level threshold.

7. The device according to claim 1 or 2, characterized in that: The signal category includes an eighth signal category, and the eighth signal category corresponds to two superimposed pulse signals, the amplitude of the former pulse signal is lower than the high level threshold and higher than the low level threshold, the amplitude of the latter pulse signal is higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold.

8. The device according to claim 1 or 2, characterized in that: The signal category includes a tenth signal category, and the tenth signal category corresponds to two independent pulse signals, and the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold.

9. A laser ranging device, characterized in that: The device comprises a laser ranging signal processing device and a calculation module as described in any one of claims 1 to 8, wherein the laser ranging signal processing device is used to obtain the laser pulse flight time, and the calculation module is used to calculate the distance value according to the laser pulse flight time.

10. A laser ranging signal processing method, characterized in that: The method includes: Converting the received laser signal into a first electrical signal; amplifying the first electrical signal and outputting a second electrical signal; Compare the second electrical signal with the low level threshold and the high level threshold respectively, and determine a first time value, a second time value, a third time value, and a fourth time value, wherein the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold; Restoring the waveform characteristics of the laser signal according to the first time value, the second time value, the third time value and the fourth time value, classifying the laser signal according to the waveform characteristics, determining the signal category, and calibrating the laser pulse flight time in a corresponding manner according to the signal category; Wherein, the signal categories include a fifth signal category, a sixth signal category, a seventh signal category and a ninth signal category, the fifth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is higher than the high level threshold; the sixth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; the seventh signal category corresponds to two superimposed pulse signals, the amplitude of the former pulse signal is higher than the high level threshold, the amplitude of the latter pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; the ninth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; The laser pulse flight time is calibrated in a corresponding manner according to the signal type, including: When the signal category is the fifth signal category, calibrating the laser pulse flight time based on the first time value and the second time value; When the signal category is the sixth signal category, calibrating the laser pulse flight time based on the second time value and the third time value; When the signal category is the seventh signal category, calibrating the laser pulse flight time based on the second time value and the third time value; When the signal category is the ninth signal category, this situation is not processed, and processing is performed after the detection point approaches and a waveform with a higher amplitude is obtained.

11. A laser ranging method, characterized in that: The method includes: Converting the received laser signal into a first electrical signal; amplifying the first electrical signal and outputting a second electrical signal; Compare the second electrical signal with the low level threshold and the high level threshold respectively, and determine a first time value, a second time value, a third time value, and a fourth time value, wherein the first time value is the time value of the first rising edge of the second electrical signal that reaches the low level threshold, the second time value is the time value of the first rising edge of the second electrical signal that reaches the high level threshold, the third time value is the time value of the first falling edge of the second electrical signal that reaches the high level threshold, and the fourth time value is the time value of the first falling edge of the second electrical signal that reaches the low level threshold; Restoring the waveform characteristics of the laser signal according to the first time value, the second time value, the third time value and the fourth time value, classifying the laser signal according to the waveform characteristics, determining the signal category, and calibrating the laser pulse flight time in a corresponding manner according to the signal category; Calculating a distance value according to the laser pulse flight time; Wherein, the signal categories include a fifth signal category, a sixth signal category, a seventh signal category and a ninth signal category, the fifth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is higher than the high level threshold; the sixth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; the seventh signal category corresponds to two superimposed pulse signals, the amplitude of the former pulse signal is higher than the high level threshold, the amplitude of the latter pulse signal is lower than the high level threshold and higher than the low level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; the ninth signal category corresponds to two superimposed pulse signals, the amplitudes of the two pulse signals are both higher than the low level threshold and lower than the high level threshold, and the amplitude of the superimposed part of the two pulse signals is lower than the high level threshold and higher than the low level threshold; The laser pulse flight time is calibrated in a corresponding manner according to the signal type, including: When the signal category is the fifth signal category, calibrating the laser pulse flight time based on the first time value and the second time value; When the signal category is the sixth signal category, calibrating the laser pulse flight time based on the second time value and the third time value; When the signal category is the seventh signal category, calibrating the laser pulse flight time based on the second time value and the third time value; When the signal category is the ninth signal category, this situation is not processed, and processing is performed after the detection point approaches and a waveform with a higher amplitude is obtained.

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