Range frequency value identification method and device based on FMCW laser radar

Abstract

The invention relates to the technical field of laser radar ranging, in particular to a distance frequency value identification method and device based on an FMCW laser radar. The method comprises the following steps: acquiring a beat frequency signal detected by an FMCW laser radar; carrying out Fourier transform on the beat frequency signal and then carrying out modulus processing to obtain frequency domain amplitude data; performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of the adjacent preset frame number; and performing low-pass filtering on the frequency domain amplitude data after time filtering, and determining a distance frequency value according to the frequency amplitude after low-pass filtering. According to the method, time filtering and low-pass filtering are performed on the frequency domain amplitude data of the beat frequency signal detected by the FMCW laser radar, so that the main frequency can be accurately identified without sacrificing the detection probability, and the influence of frequency broadening on the precision, the accuracy and the detection probability caused by introduction of Doppler frequency due to rotation of the rotating mirror is reduced.

Description

Technical Field

[0001] The present invention relates to the field of laser radar ranging technology, and in particular to a distance frequency value recognition method and device based on FMCW laser radar. Background Art

[0002] Based on the scanning method, LiDAR can be categorized as mechanical, semi-solid-state, and fully solid-state. Currently, in semi-solid-state LiDARs, a rotating mirror is often introduced to scan a laser beam at a specific horizontal angle while maintaining the transceiver system stationary. The mirror surface is a coated reflector that can achieve high reflectivity for laser beams of a fixed wavelength. As the mirror rotates at a constant speed, it can reflect laser beams incident on its surface at different times onto objects in space at different angles. After reflecting off the object, the beam returns to the mirror, where the reflected light propagates along a predetermined path and is received.

[0003] The uniform rotation of the rotating mirror enables horizontal laser scanning of space, but the problem is that the mirror's motion relative to the incident and outgoing beams introduces the Doppler effect. The Doppler effect refers to the change in the frequency received by an observer when a wave source or observer moves relative to the medium: if the wave source or observer moves closer to the source, the frequency received by the observer increases; conversely, if the wave source or observer moves away from the source, the frequency received by the observer decreases.

[0004] Among various types of lidar, FMCW (Frequency Modulated Continuous Wave) lidar uses a chirp signal—a continuous wave signal whose frequency varies linearly with time—to measure the distance to the target. The received echo signal is compared with the transmitted signal, and the frequency difference between the two is measured to calculate the target's distance. If a rotating mirror is included in an FMCW lidar, the Doppler effect of the mirror introduces a Doppler frequency into the echo signal, resulting in visible frequency broadening in the frequency domain, affecting the probability of detection and the accuracy of the calculated distance. Summary of the Invention

[0005] In view of this, the present invention provides a distance frequency value identification method and device based on FMCW laser radar to solve the problem that the setting of a rotating mirror in the FMCW laser radar causes the frequency domain to be broadened, affecting the detection probability and the calculation distance accuracy.

[0006] In a first aspect, the present invention provides a method for identifying a distance frequency value based on an FMCW laser radar, wherein the FMCW laser radar includes a rotating mirror. The method includes: obtaining a beat frequency signal detected by the FMCW laser radar, wherein the beat frequency signal is detected by a detector by an echo signal reflected by a target object and a reference wave signal; performing a Fourier transform on the beat frequency signal and performing a modulo processing to obtain frequency domain amplitude data; performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames; performing low-pass filtering on the frequency domain amplitude data after time filtering, and determining the distance frequency value based on the frequency amplitude after low-pass filtering.

[0007] In the present invention, the beat frequency signal detected by the FMCW lidar is subjected to Fourier transform and then modulo processing to obtain the corresponding frequency domain amplitude data, which is then subjected to time filtering and low-pass filtering. This allows the main frequency to be accurately identified without sacrificing the detection probability, thereby reducing the impact of frequency broadening caused by the Doppler frequency introduced by the rotation of the mirror on the precision, accuracy, and detection probability.

[0008] In an optional embodiment, the distance frequency value is determined based on the frequency amplitude after low-pass filtering, including: obtaining the main frequency broadening in the frequency domain amplitude data after low-pass filtering; calculating the center of gravity of the main frequency broadening based on the amplitude value and frequency number corresponding to each frequency in the main frequency broadening, and using the center of gravity of the main frequency broadening as the distance frequency value.

[0009] In the present invention, the main frequency still has a certain degree of broadening after low-pass filtering. Therefore, extracting the center of gravity within the broadening of the main frequency as the distance frequency value can further improve the detection accuracy.

[0010] In an optional embodiment, the frequency domain amplitude data and the frequency domain amplitude data of the adjacent preset frames are subjected to time filtering, including: averaging the frequency domain amplitude data and the frequency domain amplitude data of the adjacent preset frames to achieve time filtering.

[0011] In the present invention, an averaging process is used to perform time filtering, which is simple and requires less calculation.

[0012] In an optional implementation, the center of gravity of the main frequency broadening is calculated using the following formula:

[0013]

[0014] Where f is the frequency, A(f) is the amplitude corresponding to the frequency, and X is the number of frequencies within the main frequency span.

[0015] In the present invention, the center of gravity is calculated by the above formula, thereby achieving accurate calculation of the center of gravity.

[0016] In an optional implementation manner, the preset number of adjacent frames is any number of frames from three adjacent frames to six adjacent frames.

[0017] In the present invention, by limiting the preset number of adjacent frames, the effect of not reducing the frame rate too much and not causing an excessive delay is achieved.

[0018] In an optional implementation, the method further includes: calculating the distance of the target object to be measured according to the distance frequency value.

[0019] In a second aspect, the present invention provides a distance frequency value identification device based on an FMCW laser radar, the device comprising: a signal acquisition module for acquiring a beat frequency signal detected by the FMCW laser radar, the beat frequency signal being detected by a detector through an echo signal reflected by a target object to be measured and a reference wave signal; a frequency domain processing module for performing Fourier transform on the beat frequency signal and then performing modulo processing to obtain frequency domain amplitude data; a time filtering module for performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames; a low-pass filtering module for performing low-pass filtering on the frequency domain amplitude data after time filtering, and determining the distance frequency value based on the frequency amplitude after low-pass filtering.

[0020] In a third aspect, the present invention provides a computer device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to execute the distance frequency value identification method based on FMCW laser radar according to the above-mentioned first aspect or any corresponding embodiment thereof.

[0021] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the distance frequency value identification method based on FMCW lidar according to the above-mentioned first aspect or any corresponding embodiment thereof.

[0022] In a fifth aspect, the present invention provides a computer program product comprising computer instructions, which are used to enable a computer to execute the distance frequency value identification method based on FMCW laser radar according to the above-mentioned first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the time-frequency waveform of the signal wave and reference wave in the FMCW lidar;

[0025] Figure 2 This is a schematic diagram of the time-frequency waveforms of the signal wave and reference wave in the FMCW lidar after the Doppler frequency is introduced;

[0026] Figure 3 This is a schematic diagram showing how the amplitude of the beat signal without the rotating mirror Doppler effect changes with frequency after FFT.

[0027] Figures 4(a), 4(b), and 4(c) are schematic diagrams of the linear velocity directions of three laser beams hitting different positions of the rotating mirror;

[0028] Figure 5 is a schematic diagram of the Gaussian window function distribution of all light rays in the beam;

[0029] Figure 6 This is a schematic diagram showing how the amplitude of the beat signal with the rotating mirror Doppler effect changes with frequency after FFT.

[0030] Figure 7 1 is a flow chart of a method for identifying a distance frequency value based on an FMCW laser radar according to an embodiment of the present invention;

[0031] Figure 8 This is a schematic diagram of the time domain data of the beat frequency signal with the rotating mirror Doppler effect;

[0032] Figure 9 This is a diagram of the frequency domain amplitude of the beat signal with the rotating mirror Doppler effect;

[0033] Figure 10 is the frequency value of the beat signal without algorithm processing;

[0034] Figure 11 It is a frequency amplitude diagram after the beat frequency signal is time-filtered;

[0035] Figure 12 This is a schematic diagram of the beat signal frequency value when only time filtering is performed;

[0036] Figure 13 It is a frequency domain amplitude diagram after the beat frequency signal is time filtered and low-pass filtered;

[0037] Figure 14 It is a schematic diagram of the frequency value of the beat signal subjected to time filtering, low-pass filtering and centroid processing;

[0038] Figure 15 Schematic diagram of another method for identifying distance frequency values ​​based on FMCW laser radar according to an embodiment of the present invention

[0039] Figure 16 2 is a structural block diagram of a distance frequency value recognition device based on an FMCW laser radar according to an embodiment of the present invention;

[0040] Figure 17 Schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0042] In related technologies, the laser signal output from the FMCW laser radar is a chirp signal emitted by the laser after modulation. Figure 1 For example, in a complete cycle of the triangle wave rising edge Before entering the detector, the vibration electric fields of the reference wave signal and the echo signal (signal wave) satisfy formulas (1) and (2), respectively, where E0(t) is the vibration electric field of the reference wave signal, E1(t) is the vibration electric field of the echo signal, A0 is the vibration amplitude of the reference wave signal, A1 is the vibration amplitude of the echo signal, and the phase Yes Figure 2 The angular frequency modulation rate shown, is the initial phase, ω0 is the angular frequency of the center of the modulation period, and τ is the delay time of the echo signal relative to the reference wave signal.

[0043]

[0044] The reference wave signal and the echo signal enter the detector. Since the two beams of light come from the same light source, the light signal (beat frequency signal) after the interference between the two is:

[0045]

[0046] Where I(t) is the intensity of the synthetic field, ω b is the angular frequency of the beat signal, φ b0is the initial phase of the beat signal. It should be noted that in actual use, although the square law detection of the photodetector is used to achieve mixing, that is, the reference wave signal and the echo signal are mixed to obtain the sum frequency and the difference frequency, but due to the limitation of the bandwidth of the photodetector, only the difference frequency is obtained after filtering out the high frequency, so it is actually a beat signal, as shown in formula (3). In order to obtain the relative distance of the target object to be measured, the delay time τ of the echo signal relative to the reference wave signal must be known, that is, the angular frequency ω of the beat signal must be known. b =ατ. In order to obtain the angular frequency of the beat signal, the beat signal is processed by FFT (fast Fourier transform), and the frequency corresponding to the maximum amplitude after FFT modulo is taken as the main frequency of the beat signal. Figure 3 This is the amplitude of the beat frequency signal after FFT without the rotating mirror Doppler effect. The peak at the main frequency is clearly visible in the figure, and the remaining small peaks are caused by noise superimposed on the signal.

[0047] After the Doppler effect of the rotating mirror is introduced, the beat frequency signal changes from formula (3) to formula (4):

[0048]

[0049] Among them, ω d is the Doppler frequency introduced by the Doppler effect. At this time, the time-frequency diagram of the signal wave, reference wave and beat frequency signal becomes Figure 2 As shown, at the moment corresponding to the falling edge of the triangle wave, the angular frequency of the beat signal is (ω b +ω d ), the moment corresponding to the rising edge of the triangle wave, the angular frequency of the beat signal is (ω b -ω d ).

[0050] Based on the uniform rotation of the rotating mirror, since the incident light spot has a certain area, when it is incident on different positions of the rotating mirror, the Doppler frequency caused is different. Figures 4(a), 4(b), and 4(c) respectively show three laser beams hitting different positions of the rotating mirror. It can be seen that the linear velocity directions of the three are different, and the linear velocity decomposition 1 and linear velocity decomposition 2 of the incident and outgoing light rays are also different. At this time, the beat frequency signal after the echo signal of the entire beam beats with the reference wave signal is:

[0051]

[0052] Among them, I all (t) is the sum of the beat signals of all the light rays in the beam and the reference wave, N is the number of light rays, Gausswin(n) is the Gaussian window function, and its function distribution satisfies Figure 5 ;ω d(n) is the Doppler frequency introduced by the rotating mirror Doppler effect on each light ray, and its magnitude is related to the incident point of the light ray on the rotating mirror, the incident angle of the light ray, the speed of the rotating mirror, etc. Obviously, unless the size of the incident light spot is very small relative to the reflective surface of the rotating mirror, the beat frequency signal I all (t) contains many similar frequency components, and its amplitude after FFT is as follows: Figure 6 As shown. Figure 6 and Figure 3 , it was found that the amplitude of the original main frequency decreased, and multiple frequency peaks with similar amplitudes appeared nearby, which showed that the main frequency was broadened. Due to the broadening of the main frequency and the similarity between the main frequency amplitude and the noise amplitude, when the frequency corresponding to the highest amplitude of the FFT is used to calculate the distance to the target object, the accuracy and precision of the distance will be seriously affected. To reduce this impact, the conventional practice is to increase the amplitude threshold and not output the final distance result with an amplitude below the threshold. This method is based on sacrificing the detection probability and cannot improve the accuracy to the ideal level. An algorithm must be introduced to reduce the impact of the rotating mirror Doppler effect on the calculated distance frequency value without sacrificing the detection probability, so as to achieve the ideal distance accuracy.

[0053] According to an embodiment of the present invention, an embodiment of a method for identifying distance frequency values ​​based on an FMCW lidar is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0054] In this embodiment, a distance frequency value recognition method based on FMCW laser radar is provided. Figure 7 FIG. 1 is a flow chart of a method for identifying a distance frequency value based on an FMCW laser radar according to an embodiment of the present invention. Figure 7 As shown, the process includes the following steps:

[0055] Step S101: Obtain a beat signal detected by an FMCW laser radar, wherein the beat signal is detected by a detector using an echo signal reflected by a target object and a reference wave signal. The FMCW laser radar includes a rotating mirror.

[0056] Specifically, when the LiDAR is operating, it emits a laser beam that is incident on the reflective surface of the rotating mirror and then emitted toward the target to be measured. After being reflected by the target, the beam (i.e., the echo signal) enters the rotating mirror and returns along the output path to the LiDAR's transceiver system. Simultaneously, when emitting the laser beam toward the target, the LiDAR also outputs a laser beam signal as a reference wave signal. This reference wave signal and the echo signal are detected in a detector to generate a beat frequency signal. The detector can be a balanced photodetector.

[0057] Step S102 , performing Fourier transform on the beat frequency signal and then performing modulo processing to obtain frequency domain amplitude data.

[0058] Step S103 : performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames.

[0059] Step S104 , low-pass filtering the frequency domain amplitude data after time filtering, and determining the distance frequency value according to the frequency amplitude after low-pass filtering.

[0060] Specifically, according to the above-mentioned related technologies, it is known that FMCW laser radar needs to extract the main frequency in the beat signal when performing distance measurement. In order to extract the main frequency, the beat signal is subjected to fast Fourier transform and then modulo-modulated to obtain the frequency domain amplitude data of the beat signal. For example, for a FMCW laser radar including a rotating mirror, the beat signal detected by it is as follows: Figure 8 As shown, the frequency domain amplitude image corresponding to the frequency domain amplitude data of the beat frequency signal is as follows Figure 9 As shown in the figure, it can be seen that due to the influence of the rotating mirror Doppler effect, the amplitude of the main frequency is close to the surrounding noise, and the main frequency is severely broadened. If no algorithm processing is performed, the frequency corresponding to the maximum amplitude is taken as the range frequency. The range frequency value calculated for each pixel is as follows: Figure 10 As shown. Since the laser beam scans in three-dimensional space, a frame of data contains x rows and y columns of pixels, so Figure 10 Contains the distance frequency values ​​of x*y pixels. Figure 10 It contains not only the correct range-frequency values, but also a large number of range-frequency values ​​that are incorrectly calculated due to the Doppler effect of the rotating mirror.

[0061] Thus, after processing the beat signal to obtain frequency domain amplitude data, temporal filtering is performed on the beat signal and the frequency domain amplitude data of adjacent preset frames to attenuate rapidly varying components in the signal. It should be noted that in this embodiment, the beat signal obtained and the converted frequency domain amplitude data represent a single frame of data. During temporal filtering, the frequency domain amplitude data obtained by converting the beat signal of adjacent preset frames of the frame of data is then obtained. That is, the frequency domain amplitude data of multiple frames are combined to perform temporal filtering on the frequency domain amplitude data of the frame.

[0062] Among them, the effect after time filtering is as follows Figure 11 As shown in , the peak near the main frequency is more obvious than the rest of the noise. In the case of only frequency domain time filtering, the distance frequency value of a frame of data is as follows Figure 12 , there are still some erroneous distance frequency values. Therefore, based on time filtering, the frequency domain amplitude data after time filtering is low-pass filtered to solve the problems of noise interference and frequency broadening. Among them, the frequency domain amplitude data after low-pass filtering is as follows Figure 13As shown in the figure, it can be seen that the noise is very small relative to the main frequency. The main frequency (distance frequency) required can be extracted from it for subsequent distance calculation.

[0063] In addition, the low-pass filtering process refers to low-pass filtering in frequency, wherein the main frequency is sparser than the noise in the frequency domain, that is, the frequency at the main frequency is lower, so high-frequency noise with a higher frequency can be removed by low-pass filtering.

[0064] The method for identifying distance frequency values ​​based on FMCW lidar provided in an embodiment of the present invention obtains corresponding frequency domain amplitude data by performing Fourier transform on the beat frequency signal detected by the FMCW lidar and then performing modulo processing. The frequency domain amplitude data is then subjected to time filtering and low-pass filtering. This allows the main frequency to be accurately identified without sacrificing the detection probability, thereby reducing the impact of frequency broadening caused by the Doppler frequency introduced by the rotation of the mirror on the accuracy, precision, and detection probability.

[0065] In this embodiment, a method for identifying a distance frequency value based on an FMCW laser radar is provided. The method includes the following steps:

[0066] Step S201: Obtain a beat signal detected by an FMCW laser radar. The beat signal is detected by a detector using an echo signal reflected by a target object and a reference wave signal. The FMCW laser radar includes a rotating mirror. Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0067] Step S202: Perform Fourier transform on the beat frequency signal and then perform modulo processing to obtain frequency domain amplitude data. Figure 1 Step S102 of the illustrated embodiment will not be described in detail here.

[0068] Step S203 , performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames.

[0069] Specifically, the above step S203 includes:

[0070] Step S2031: averaging the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames to implement time filtering, wherein the preset number of adjacent frames is any number of frames from three adjacent frames to six adjacent frames.

[0071] Specifically, the adjacent preset number of frames can be the adjacent preset number of frames before and after the frequency domain amplitude data of the current frame. Among them, the adjacent preset number of frames can be three adjacent frames, four adjacent frames, five adjacent frames, or six adjacent frames, etc. In this embodiment, the frequency domain amplitude data and the frequency domain amplitude data of the four adjacent frames before and after the frequency domain amplitude data are selected for averaging processing, thereby not only achieving a better filtering effect, but also not reducing the frame rate too much and not causing excessive delay. In addition, time filtering is achieved by averaging processing, and the processing method is simple.

[0072] Step S204 , low-pass filtering the frequency domain amplitude data after the time filtering, and determining the distance frequency value according to the frequency amplitude after the low-pass filtering.

[0073] Specifically, the above step S204 includes:

[0074] Step S2041: Obtain the main frequency spread in the frequency domain amplitude data after low-pass filtering; calculate the center of gravity of the main frequency spread based on the amplitude value and the number of frequencies corresponding to each frequency in the main frequency spread, and use the center of gravity of the main frequency spread as the distance frequency value. The center of gravity of the main frequency spread is calculated using the following formula:

[0075]

[0076] Where f is the frequency, A(f) is the amplitude corresponding to the frequency, and X is the number of frequencies within the main frequency span.

[0077] Among them, after low-pass filtering, although the noise is very small relative to the main frequency, the main frequency still has a certain width, and directly determining the main frequency at this time may still have errors. Therefore, this embodiment determines its center of gravity within the main frequency width, and uses the frequency corresponding to the center of gravity as the distance frequency value, thereby further improving the distance accuracy. After frequency domain time filtering, low-pass filtering and taking the center of gravity, we finally get Figure 14 The distance frequency value of . Figure 10 No algorithm processing, Figure 12 The distance frequency value is processed only by time filtering. Figure 14 There are basically no error frequency values, and the distribution of distance frequency values ​​is more concentrated.

[0078] In order to illustrate the reliability of the above method in improving the detection probability, Figure 10 、 12An amplitude threshold is set for the distance-frequency data of 14, filtering out distance-frequency values ​​with amplitudes less than the threshold. The threshold is set to just filter out all erroneous frequency values. For unprocessed data, an amplitude threshold of 13.9 results in a detection probability (the proportion of unfiltered, normally output data within a given time period) of 37.9%. For data that undergoes only time filtering, an amplitude threshold of 8.1 results in a detection probability of 81.8%. For data that undergoes time filtering, low-pass filtering, and centroid-based frequency extraction, an amplitude threshold of 5 results in a detection probability of 99.6%.

[0079] Step S205: Calculate the distance of the target object to be measured according to the distance frequency value. Specifically, the distance of the target object to be measured can be calculated according to the following formula:

[0080]

[0081] Where R is the distance between the radar and the target; T is the sweep frequency period of the transmitted signal; c is the speed of light; f b represents the main frequency of the beat signal; B represents the sweep bandwidth.

[0082] As a specific application example of the embodiment of the present invention, Figure 15 As shown, the distance frequency value recognition method based on FMCW laser radar is implemented using the following process:

[0083] The laser beam output by the laser in an FMCW lidar is incident on the coated reflective surface of the rotating mirror and then emitted to the target to be measured. After reflection from the target, the beam enters the rotating mirror and returns to the radar's transceiver system along the output path. The echo signal and the reference wave signal beat in the balanced detector, generating a beat signal. The beat signal is subjected to an FFT, and its frequency domain amplitude image is obtained after taking the modulus. The frequency domain amplitude data of four adjacent frames of the beat signal are averaged to implement time filtering. After filtering, the peak near the main frequency is more prominent than the remaining noise. Even when only frequency domain time filtering is performed, some erroneous distance frequency values ​​still exist.

[0084] To further address the issues of noise interference and frequency broadening, the beat signal's frequency domain amplitude data is low-pass filtered in addition to time filtering. At this point, the noise is very small relative to the main frequency, but the main frequency still has some broadening. Based on this, the center of gravity of the amplitude image within the main frequency broadening is taken, and the frequency corresponding to the center of gravity is used as the distance frequency value to further improve distance accuracy. The calculation formula for the center of gravity is:

[0085]

[0086] Where f is the frequency, A(f) is the amplitude corresponding to the frequency, and X is the number of frequencies within the main frequency span. After the distance frequency value is calculated, the distance is calculated based on the distance frequency value.

[0087] This embodiment also provides a distance frequency value identification device based on an FMCW laser radar. This device is used to implement the above-mentioned embodiments and preferred embodiments. Details that have already been described will not be repeated here. As used below, the term "module" may refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0088] This embodiment provides a distance frequency value recognition device based on FMCW laser radar, such as Figure 16 Shown, including:

[0089] The signal acquisition module 161 is used to acquire a beat signal detected by the FMCW laser radar, where the beat signal is detected by a detector using an echo signal reflected by the target object and a reference wave signal;

[0090] A frequency domain processing module 162 is configured to perform a Fourier transform on the beat frequency signal and then perform a modulo process to obtain frequency domain amplitude data;

[0091] A time filtering module 163 is configured to perform time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames;

[0092] The low-pass filtering module 164 is configured to perform low-pass filtering on the frequency domain amplitude data after time filtering, and determine the range frequency value according to the frequency amplitude after low-pass filtering.

[0093] The further functional description of each of the above modules is the same as that of the above corresponding embodiments and will not be repeated here.

[0094] The embodiment of the present invention also provides a computer device having the above Figure 16 The distance frequency value recognition device based on FMCW laser radar is shown.

[0095] See also Figure 17 , Figure 17 is a structural diagram of a computer device provided by an optional embodiment of the present invention, such as Figure 17As shown, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in the memory or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Equally, multiple computer devices can be connected, and each device provides part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 17 A processor 10 is taken as an example.

[0096] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0097] The memory 20 stores instructions that can be executed by at least one processor 10, so as to enable at least one processor 10 to execute the method shown in the above embodiment.

[0098] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created based on the use of a computer device for displaying a small program landing page, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0099] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0100] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0101] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0102] A portion of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the form in which the computer program instruction exists in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc. Accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium that can be accessed by the computer.

[0103] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A distance frequency value recognition method based on FMCW laser radar, characterized in that: The FMCW laser radar includes a rotating mirror, and the method includes: Acquire a beat signal detected by the FMCW laser radar, where the beat signal is detected by a detector using an echo signal reflected by a target object and a reference wave signal; Performing Fourier transformation on the beat frequency signal and performing modulo processing to obtain frequency domain amplitude data; Performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames; The frequency domain amplitude data after time filtering is low-pass filtered, and the distance frequency value is determined according to the frequency amplitude after low-pass filtering.

2. The method according to claim 1, characterized in that The distance frequency value is determined based on the frequency amplitude after low-pass filtering, including: Obtain the main frequency broadening in the frequency domain amplitude data after low-pass filtering; The center of gravity of the main frequency broadening is calculated based on the amplitude value and the number of frequencies corresponding to each frequency in the main frequency broadening, and the center of gravity of the main frequency broadening is used as the distance frequency value.

3. The method according to claim 1, characterized in that The frequency domain amplitude data and the frequency domain amplitude data of the adjacent preset frames are subjected to time filtering, including: The frequency domain amplitude data and the frequency domain amplitude data of adjacent preset frames are averaged to achieve time filtering.

4. The method according to claim 2, characterized in that: The center of gravity of the main frequency broadening is calculated using the following formula: Where f is the frequency, A(f) is the amplitude value corresponding to the frequency, and X is the number of frequencies within the main frequency span.

5. The method according to claim 1, characterized in that The preset number of adjacent frames is any number of adjacent three frames to adjacent six frames.

6. The method according to claim 1, characterized in that The method further comprises: The distance of the target object to be measured is calculated according to the distance frequency value.

7. A distance frequency value recognition device based on FMCW laser radar, characterized in that: The device comprises: A signal acquisition module is used to acquire a beat frequency signal detected by the FMCW laser radar, wherein the beat frequency signal is detected by a detector using an echo signal reflected by a target object and a reference wave signal; A frequency domain processing module, used for performing Fourier transform on the beat frequency signal and performing modulus processing to obtain frequency domain amplitude data; A time filtering module, used for performing time filtering on the frequency domain amplitude data and the frequency domain amplitude data of a preset number of adjacent frames; The low-pass filtering module is used to perform low-pass filtering on the frequency domain amplitude data after time filtering, and determine the distance frequency value according to the frequency amplitude after low-pass filtering.

8. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the distance frequency value recognition method based on FMCW laser radar according to any one of claims 1 to 6 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the distance frequency value recognition method based on FMCW laser radar according to any one of claims 1 to 6.

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