A method for measuring the movement direction and a lidar system

Abstract

This application is applicable to the field of radar technology, and provides a method for measuring the direction of motion and a lidar system. By controlling the linearity of the up-sweeping signal and the down-sweeping signal of the transmitted signal to be inconsistent, the spectrum peak value of the rising edge and the spectrum peak value of the falling edge are made inconsistent after time-frequency transformation, so as to realize the regions of the up-sweeping signal and the down-sweeping signal, and further realize the measurement of the velocity direction. The velocity direction of the target object can be determined only through one-time measurement, without increasing the system volume while maintaining the calculation accuracy, improving the efficiency of measuring the velocity direction and reducing the complexity of the algorithm, and no longer needing to store the result of the previous measurement.

Description

Technical Field

[0001] This application belongs to the technical field of radar, and particularly relates to a method for measuring the direction of motion and a lidar system. Background Art

[0002] A Frequency Modulated Continuous Wave (FMCW) radar refers to a continuous wave radar whose transmitted frequency is modulated by a specific signal.

[0003] The FMCW radar can accurately measure the distance and speed magnitude of a target object. However, since the two spectral peak heights of the calculated distance and speed are similar and the relative magnitudes are not fixed, it can only measure the magnitude of the motion speed of the target object, but cannot accurately measure the direction of motion of the target object. Summary of the Invention

[0004] Embodiments of this application provide a method for measuring the direction of motion and a lidar system, which can solve the problem that the FMCW radar can only measure the magnitude of the motion speed of a target object, but cannot accurately measure the direction of motion of the target object.

[0005] In a first aspect, a method for measuring the direction of motion is provided, which is applied to an FMCW radar. The method for measuring the direction of motion includes:

[0006] Controlling the FMCW radar to transmit a transmitted signal, and the transmitted signal forms an echo signal after being reflected by a target object; wherein, the transmitted signal includes an up-chirp signal and a down-chirp signal, and the linearity of the up-chirp signal is inconsistent with the linearity of the down-chirp signal;

[0007] Controlling the FMCW radar to receive the echo signal, and mixing the echo signal and the transmitted signal to obtain a difference frequency signal;

[0008] Performing time-frequency transformation on the difference frequency signal to obtain a frequency domain signal;

[0009] Determining the direction of motion of the target object based on the frequency domain signal.

[0010] In a possible implementation manner of the first aspect, before controlling the FMCW radar to transmit the transmitted signal, it further includes:

[0011] Adjusting the scanning frequency of the up-chirp signal with a first linearity;

[0012] Adjusting the scanning frequency of the down-chirp signal with a second linearity;

[0013] The first linearity is not equal to the second linearity.

[0014] In a possible implementation of the first aspect, determining the motion direction of the target object based on the frequency-domain signal includes:

[0015] Determining the frequency of the first main peak and the frequency of the second main peak based on the frequency-domain signal, where the first main peak is the main peak with a large amplitude, and the second main peak is the main peak with a small amplitude;

[0016] Calculating the motion direction of the target object according to the frequency of the first main peak and the frequency of the second main peak.

[0017] In a possible implementation of the first aspect, the calculation formula for calculating the motion direction of the target object according to the frequency of the first main peak and the frequency of the second main peak is:

[0018] v = coe * (f b - f s );

[0019] where coe is the conversion coefficient between speed and frequency difference, f b is the frequency of the first main peak, and f s is the frequency of the second main peak;

[0020] If v is a positive number, the motion direction of the target object is the calibrated positive direction, and if v is a negative number, the motion direction of the target object is the calibrated negative direction.

[0021] In a possible implementation of the first aspect, it further includes: setting the conversion coefficient based on the first linearity and the second linearity.

[0022] In a possible implementation of the first aspect, after performing time-frequency transformation on the difference-frequency signal to obtain a frequency-domain signal, it further includes:

[0023] Calculating the distance and speed magnitude of the target object according to the frequency-domain signal.

[0024] In a second aspect, a lidar system is provided, including:

[0025] A modulation module, configured to provide a modulation signal for a signal transceiver module, where the modulation signal is used to adjust the frequency of a transmitted signal, and the transmitted signal includes an up-sweeping frequency signal and a down-sweeping frequency signal, and the linearity of the up-sweeping frequency signal is inconsistent with the linearity of the down-sweeping frequency signal;

[0026] A signal transceiver module, connected to the modulation module, configured to transmit the transmitted signal and receive an echo signal reflected by a target object;

[0027] The signal processing module, connected to the signal transceiver module, is configured to process the transmitted signal and the echo signal to measure the movement direction of the target object.

[0028] In a possible implementation manner of the second aspect, the modulation module is specifically configured to adjust the scanning frequency of the up-sweeping signal with a first linearity; adjust the scanning frequency of the down-sweeping signal with a second linearity; and the first linearity is not equal to the second linearity.

[0029] In a possible implementation manner of the second aspect, the signal transceiver module includes a transmitter, a receiver, and a focusing module;

[0030] The transmitter is configured to transmit the transmitted signal;

[0031] The focusing module is configured to concentrate the energy of the transmitted signal and the energy of the received echo signal;

[0032] The receiver is configured to receive the echo signal.

[0033] In a possible implementation manner of the second aspect, the signal transceiver module is specifically configured to mix the transmitted signal and the echo signal to obtain a difference frequency signal, and the signal processing module is specifically configured to perform time-frequency conversion on the difference frequency signal to obtain a frequency domain signal, and determine the movement direction of the target object based on the frequency domain signal.

[0034] The beneficial effects of the embodiments of the present application compared with the prior art are as follows: By controlling the linearities of the up-sweeping signal and the down-sweeping signal of the transmitted signal to be inconsistent, the spectrum peaks at the rising edge and the spectrum peaks at the falling edge are different after time-frequency transformation, and the regions of the up-sweeping signal and the down-sweeping signal are realized, thereby realizing the measurement of the speed direction. The speed direction of the target object can be determined only through one-time measurement, without increasing the system volume while maintaining the calculation accuracy, improving the efficiency of measuring the speed direction and reducing the complexity of the algorithm, and no longer requiring the storage of the previous measurement result. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic structural diagram of a lidar system provided by an embodiment of the present application;

[0037] Figure 2 Schematic diagram of the implementation process of a motion direction measurement method provided by an embodiment of the present application;

[0038] Figure 3 It is an example diagram of the curve of the signal frequency received by a signal transceiver module changing with time provided by an embodiment of the present application;

[0039] Figure 4 is Figure 3 Schematic diagram of the waveform of the difference frequency signal obtained after mixing the transmitted signal and the echo signal shown;

[0040] Figure 5 is Figure 4 Schematic diagram of the waveform of the frequency domain signal obtained after time-frequency conversion of the difference frequency signal shown. Specific embodiments

[0041] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are proposed to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0042] It should be understood that when used in the specification of the present application and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0043] It should also be understood that the term "and / or" as used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0044] As used in the specification of the present application and the appended claims, the term "if" can be interpreted as "when...", "once", "in response to determining", or "in response to detecting" depending on the context. Similarly, the phrase "if determined" or "if [the described condition or event] is detected" can be interpreted as meaning "once determined", "in response to determining", "once [the described condition or event] is detected", or "in response to detecting [the described condition or event]" depending on the context.

[0045] In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0046] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that specific features, structures, or characteristics described in connection with that embodiment are included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0047] Frequency Modulated Continuous Wave (FMCW) radar can quickly measure the distance and speed magnitude of a target object. However, the two spectral peak heights used to calculate the distance and speed are similar, and the relative magnitudes are not fixed, resulting in only being able to calculate the magnitude of the speed and not being able to accurately calculate the direction of motion. To address this problem, currently, when an FMCW radar determines the direction of motion of a target object, it can perform two measurements and then determine the direction of motion of the target object based on the ratio of the displacement difference and time difference in the results of the two measurements. However, this method not only requires storing the previous measurement results but also has a certain time delay effect and is easily interfered by random measurement errors, resulting in inaccurate measurement results. Or, by controlling the acquisition moment with a trigger signal, perform a time-frequency transform on the rising edge time and falling edge time respectively, and then perform calculations. However, this calculation method requires controlling the synchronization of the trigger signal, and since the amount of data participating in the time-frequency transform decreases each time, the frequency resolution becomes smaller, so the calculation accuracy is reduced.

[0048] Based on this, the embodiments of this application provide a method for measuring the direction of motion and a lidar system. By controlling the linearity of the up-sweeping signal and the down-sweeping signal of the transmitted signal to be inconsistent, the spectral peak of the rising edge and the spectral peak of the falling edge after time-frequency transform are made to be different in height, realizing the regions of the up-sweeping signal and the down-sweeping signal, and thus realizing the measurement of the speed direction. The speed direction of the target object can be determined through a one-time measurement, maintaining the calculation accuracy without increasing the system volume, improving the efficiency of measuring the speed direction while reducing the complexity of the algorithm, and no longer requiring storing the previous measurement results.

[0049] Please refer to Figure 1 As shown in Figure 1 , the embodiments of this application provide a lidar system 10. As

[0050] The modulation module 110 is configured to provide a modulation signal for the signal transceiver module 120.

[0051] Among them, the modulation signal is used to adjust the frequency of the transmitted signal. The transmitted signal includes an up-sweeping frequency signal and a down-sweeping frequency signal, and the linearity of the up-sweeping frequency signal is inconsistent with the linearity of the down-sweeping frequency signal.

[0052] Herein, the above-mentioned up-sweeping frequency signal refers to the signal interval where the frequency of the transmitted signal increases, and the down-sweeping frequency signal refers to the signal interval where the frequency of the transmitted signal decreases.

[0053] The signal transceiver module 120, connected to the modulation module 110, is configured to transmit the transmitted signal and receive the echo signal reflected by the target object.

[0054] The transmitted signal emitted by the signal transceiver module 120 forms an echo signal after being reflected by the target object in space, and the signal transceiver module 120 will receive the echo signal within its receivable range.

[0055] The signal processing module 130, connected to the signal transceiver module 120, is configured to process the transmitted signal and the echo signal to measure the moving direction of the target object.

[0056] In an embodiment of the present application, the modulation module 110 is specifically configured to adjust the scanning frequency of the up-sweeping frequency signal with a first linearity; and adjust the scanning frequency of the down-sweeping frequency signal with a second linearity.

[0057] Among them, the first linearity is not equal to the second linearity. In practical applications, the first linearity can be set to be better than the second linearity, or the second linearity can be set to be better than the first linearity. The present application does not limit this.

[0058] Specifically, the modulation module 110 can control the linearity of the modulation signal, thereby realizing the adjustment of the linearity of the up-sweeping frequency signal and the linearity of the down-sweeping frequency signal.

[0059] In an embodiment of the present application, the signal transceiver module 120 includes a transmitter, a receiver, and a focusing module.

[0060] The transmitter is configured to transmit the above-mentioned transmitted signal.

[0061] The focusing module is configured to concentrate the energy of the transmitted signal and the energy of the received echo signal;

[0062] The receiver is configured to receive the echo signal.

[0063] In an embodiment of the present application, the signal transceiver module 120 is specifically configured to mix the transmitted signal and the echo signal to obtain a difference frequency signal.

[0064] The signal processing module 130 is specifically configured to perform time-frequency conversion on the difference frequency signal to obtain a frequency-domain signal, and determine the movement direction of the target object based on the frequency-domain signal.

[0065] In the embodiment of the present application, the above-mentioned time-frequency conversion of the difference frequency signal to obtain a frequency-domain signal can be achieved through frequency-domain transformation methods such as Fourier transform and inverse Fourier transform, which will not be elaborated in this application.

[0066] The signal processing module 130 can also perform processing such as spectrum refinement and spectrum enhancement on the transformed frequency-domain signal. Among them, spectrum refinement can be achieved through spectrum refinement methods such as the CZT algorithm and the ZoomFFT algorithm, and spectrum enhancement can be achieved through spectrum enhancement methods such as the accumulation algorithm and the multiplication algorithm, which will not be elaborated in this application.

[0067] The signal processing module 130 determines the movement direction of the target object based on the frequency-domain signal, and can achieve the calculation of the movement magnitude of the target object and the distance of the target object through existing distance-velocity demodulation algorithms. For the movement direction of the target object, reference can be made to the description in the embodiment of the movement direction measurement method, which will not be elaborated in this application.

[0068] As can be seen above, the lidar system provided by the embodiment of the present application realizes the inconsistent spectral peaks of the rising edge and the falling edge after time-frequency conversion by controlling the linearity of the up-sweeping signal and the linearity of the down-sweeping signal of the transmitted signal to be inconsistent, realizes the regions of the up-sweeping signal and the down-sweeping signal, and further realizes the measurement of the velocity direction. It can determine the velocity direction of the target object only through one-time measurement, without increasing the system volume while maintaining the calculation accuracy, improving the efficiency of measuring the velocity direction and reducing the complexity of the algorithm, and no longer requiring the storage of the previous measurement result.

[0069] Based on Figure 1 the lidar system shown, the embodiment of the present application provides a movement direction measurement method, which is applied to an FMCW radar.

[0070] Please refer to Figure 2 , Figure 2 which shows a schematic implementation flowchart of a movement direction measurement method provided by the embodiment of the present application. As Figure 2 shown, the movement measurement method provided by the embodiment of the present application includes S11 to S14, which are described in detail as follows:

[0071] S11: Control the FMCW radar to transmit a transmitted signal.

[0072] Among them, the transmitted signal forms an echo signal after being reflected by the target object.

[0073] The transmitted signal includes an up-chirp signal and a down-chirp signal, and the linearity of the up-chirp signal is inconsistent with that of the down-chirp signal.

[0074] In an embodiment of the present application, the linearity of the up-chirp signal and the linearity of the down-chirp signal are adjusted by a modulation module in the FMCW radar, so that the linearity of the up-chirp signal is inconsistent with that of the down-chirp signal.

[0075] The up-chirp signal refers to the signal interval in which the frequency of the transmitted signal increases, and the down-chirp signal refers to the signal interval in which the frequency of the transmitted signal decreases.

[0076] Exemplarily, Figure 3 shows a schematic diagram of the curve of the signal frequency received by the signal transceiver module changing with time. It can be Figure 3 seen that the linearity of the up-chirp signal is inconsistent with that of the down-chirp signal (the frequency change of the up-chirp signal is shown as a straight line, and the frequency change of the down-chirp signal fluctuates).

[0077] In a specific application, the above-mentioned transmitted signal can be transmitted through a focusing module, so as to effectively concentrate the energy of the transmitted signal.

[0078] In an embodiment of the present application, before S11, the following steps are further included:

[0079] Adjust the sweep frequency of the up-chirp signal with a first linearity;

[0080] Adjust the sweep frequency of the down-chirp signal with a second linearity;

[0081] Wherein, the first linearity is not equal to the second linearity.

[0082] In a specific application, a modulation signal can be sent to the signal transceiver module through a modulation module to achieve the effect of adjusting the sweep frequency of the up-chirp signal with a first linearity and adjusting the sweep frequency of the down-chirp signal with a second linearity.

[0083] S12: Control the FMCW radar to receive the echo signal, and mix the echo signal and the transmitted signal to obtain a difference frequency signal.

[0084] In a specific application, after receiving the above echo signal through a receiver, the echo signal is focused by a focusing module. At the same time, the echo signal and the transmitted signal can be mixed to obtain a difference frequency signal.

[0085] Exemplarily, as Figure 3 shown, the waveform of the difference frequency signal obtained after mixing the transmitted signal and the echo signal is as Figure 4 shown.

[0086] S13: Perform time-frequency transformation on the difference frequency signal to obtain a frequency-domain signal.

[0087] In a specific application, after obtaining the difference frequency signal, time-frequency conversion and solution processing can be performed through a signal processing module.

[0088] The above-mentioned time-frequency transformation of the difference frequency signal to obtain a frequency-domain signal can be achieved through frequency-domain transformation methods such as Fourier transform and inverse Fourier transform, which will not be elaborated in this application.

[0089] In a specific application, spectrum refinement, spectrum enhancement, etc. can also be performed on the transformed frequency-domain signal. Among them, spectrum refinement can be achieved through spectrum refinement methods such as the CZT algorithm and the ZoomFFT algorithm, and spectrum enhancement can be achieved through spectrum enhancement methods such as the accumulation algorithm and the multiplication algorithm, which will not be elaborated in this application.

[0090] Exemplarily, as Figure 4 shown, after performing time-frequency transformation on the difference frequency signal, a frequency-domain waveform as Figure 5 shown can be obtained. It can be seen from Figure 5 that there are two main peaks in the frequency-domain signal. The first main peak refers to the main peak with a larger amplitude, and the second main peak refers to the main peak with a smaller amplitude.

[0091] S14: Determine the movement direction of the target object based on the frequency-domain signal.

[0092] In the embodiment of this application, after determining the two main peaks in the frequency-domain signal, the movement direction of the target object can be determined based on the two main peaks in the frequency-domain signal.

[0093] In an embodiment of this application, S14 specifically includes the following steps:

[0094] Determine the frequency of the first main peak and the frequency of the second main peak based on the frequency-domain signal, where the first main peak is the main peak with a large amplitude and the second main peak is the main peak with a small amplitude;

[0095] Calculate the movement direction of the target object according to the frequency of the first main peak and the frequency of the second main peak.

[0096] The calculation formula for calculating the movement direction of the target object according to the frequency of the first main peak and the frequency of the second main peak is as follows:

[0097] v = coe * (f b - f s );

[0098] where coe is the conversion coefficient between speed and frequency difference, f b is the frequency of the first main peak, and f s is the frequency of the second main peak;

[0099] If v is a positive number, the moving direction of the target object is the calibrated positive direction; if v is a negative number, the moving direction of the target object is the calibrated negative direction.

[0100] In the embodiments of the present application, a conversion coefficient can be set based on the first linearity and the second linearity. Specifically, the positive and negative values of the conversion coefficient can be set based on the first linearity and the second linearity. Specifically, when the first linearity is greater than the second linearity, the conversion coefficient can be set to be positive; when the first linearity is less than the second linearity, the conversion coefficient can be set to be negative. Of course, when the first linearity is greater than the second linearity, the conversion coefficient can also be set to be negative; when the first linearity is less than the second linearity, the conversion coefficient can be set to be positive. The present application does not limit this.

[0101] In the embodiments of the present application, the moving direction away from the FMCW radar can be defined as the positive direction, and the moving direction towards the FMCW radar can be defined as the negative direction. Of course, the moving direction away from the FMCW radar can also be defined as the negative direction, and the moving direction towards the FMCW radar can be defined as the positive direction. The present application does not limit this.

[0102] In an embodiment of the present application, after performing time-frequency transformation on the difference frequency signal to obtain a frequency-domain signal, in addition to measuring the moving direction of the target object, the distance and speed magnitude of the target object can also be calculated based on the frequency-domain signal.

[0103] As can be seen from the above, the moving direction measurement method provided by the embodiments of the present application can also achieve inconsistent spectral peaks at the rising edge and the falling edge after time-frequency transformation by controlling the linearity of the up-chirp signal and the down-chirp signal of the transmitted signal to be inconsistent, so as to realize the regions of the up-chirp signal and the down-chirp signal, and further realize the measurement of the speed direction. The speed direction of the target object can be determined only through one-time measurement, which can maintain the calculation accuracy without increasing the system volume, improve the efficiency of measuring the speed direction, reduce the complexity of the algorithm, and no longer need to store the result of the previous measurement.

[0104] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above division of each functional unit and module is used as an example. In practical applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0105] The embodiment of this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments can be implemented.

[0106] The embodiment of this application provides a computer program product. When the computer program product runs on a mobile terminal, the mobile terminal can implement the steps in the above method embodiments when executed.

[0107] If the above integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above method embodiments of this application, a computer program can be used to instruct the relevant hardware to complete. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps in the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the photographing device / terminal device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disc, etc. In some jurisdictions, according to legislation and patent practice, the computer-readable medium cannot be an electrical carrier signal and a telecommunication signal.

[0108] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0109] Those of ordinary skill in the art will appreciate that the units and algorithm steps of the examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0110] In the embodiments provided in this application, it should be understood that the disclosed apparatus / node device and method can be implemented in other ways. For example, the apparatus / node device embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the device or unit can be in electrical, mechanical or other forms.

[0111] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0112] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for measuring the direction of movement, characterized in that Applied to an FMCW radar, the method for measuring the movement direction includes: Controlling the FMCW radar to transmit a transmitted signal, and the transmitted signal forms an echo signal after being reflected by a target object; wherein, the transmitted signal includes an up-chirp signal and a down-chirp signal, and the linearity of the up-chirp signal is inconsistent with the linearity of the down-chirp signal; Controlling the FMCW radar to receive the echo signal, and mixing the echo signal and the transmitted signal to obtain a difference frequency signal; Performing time-frequency transformation on the difference frequency signal to obtain a frequency-domain signal; Determining the movement direction of the target object based on the frequency-domain signal.

2. The motion direction measurement method according to claim 1, characterized in that Before controlling the FMCW radar to transmit the transmitted signal, it further includes: Adjusting the scanning frequency of the up-chirp signal with a first linearity; Adjusting the scanning frequency of the down-chirp signal with a second linearity; The first linearity is not equal to the second linearity.

3. The motion direction measurement method according to claim 1, wherein The determining the movement direction of the target object based on the frequency-domain signal includes: Determining the frequency of the first main peak and the frequency of the second main peak based on the frequency-domain signal, wherein the first main peak is the main peak with a large amplitude, and the second main peak is the main peak with a small amplitude; Calculating the movement direction of the target object according to the frequency of the first main peak and the frequency of the second main peak.

4. The method for measuring the movement direction according to claim 3, wherein The calculation formula for calculating the movement direction of the target object according to the frequency of the first main peak and the frequency of the second main peak is: v = coe*(f b - f s ); Among them, coe is the conversion coefficient of speed and frequency difference, and f b is the frequency of the first main peak, and f s is the frequency of the second main peak; If v is a positive number, the movement direction of the target object is the calibrated positive direction; if v is a negative number, the movement direction of the target object is the calibrated negative direction.

5. The method for measuring the movement direction according to claim 4, wherein It further includes: Setting the conversion coefficient based on the first linearity and the second linearity.

6. The method for measuring the movement direction according to any one of claims 1 to 5, characterized in that After performing time-frequency transformation on the difference frequency signal to obtain a frequency-domain signal, it further includes: Calculating the distance and speed magnitude of the target object according to the frequency-domain signal.

7. A lidar system, characterized in that, It includes: A modulation module for providing a modulation signal for the signal transceiver module, and the modulation signal is used to adjust the frequency of the transmitted signal. The transmitted signal includes an up-chirp signal and a down-chirp signal, and the linearity of the up-chirp signal is inconsistent with the linearity of the down-chirp signal; A signal transceiver module connected to the modulation module for transmitting the transmitted signal and receiving the echo signal reflected by the target object; The signal processing module connected to the signal transceiver module for processing the transmitted signal and the echo signal to measure the movement direction of the target object.

8. The lidar system according to claim 7, wherein, The modulation module is specifically used to adjust the scanning frequency of the up-chirp signal with a first linearity; adjust the scanning frequency of the down-chirp signal with a second linearity; the first linearity is not equal to the second linearity.

9. The lidar system according to claim 7, wherein, The signal transceiver module includes a transmitter, a receiver, and a focusing module; The transmitter for transmitting the transmitted signal; The focusing module for concentrating the energy of the transmitted transmitted signal and the energy of the received echo signal; The receiver for receiving the echo signal.

10. The lidar system according to claim 7, characterized in that, The signal transceiver module is specifically configured to mix the transmitted signal and the echo signal to obtain a difference frequency signal. The signal processing module is specifically configured to perform time-frequency conversion on the difference frequency signal to obtain a frequency domain signal, and determine the motion direction of the target object based on the frequency domain signal.

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