Target detection methods, lidar, and equipment based on frequency modulated continuous wave

Abstract

This invention provides a target detection method, lidar, and device based on frequency-modulated continuous wave (FM-CVT), comprising: emitting a probe wave and receiving the echo after the probe wave is reflected off a target object; acquiring frequency sweep data corresponding to all frequency sweeps; combining multiple frequency sweep data to obtain at least one set of frequency sweep arrays; and demodulating the at least one set of frequency sweep arrays to obtain the distance and / or velocity of the target object. By ensuring that the probe wave contains multiple frequency sweeps with different slopes in each frequency sweep cycle and combining the frequency sweep data corresponding to the frequency sweeps, the frequency sweep data can be reused during demodulation, thereby effectively improving the point cloud density per unit time. Simultaneously, by independently demodulating and calculating the distance and / or velocity of the target object using multiple frequency sweeps, the problem of ambiguity in the results can be effectively avoided. Thus, without increasing hardware resources, the problem of how to effectively improve the accuracy of target detection based on FM-CVT is solved.

Description

Technical Field

[0001] This invention relates to the field of signal processing technology, and in particular to a target detection method, lidar, and device based on frequency-modulated continuous wave. Background Technology

[0002] Frequency Modulated Continuous Wave Radar (FMCW radar) is a continuous wave radar whose transmission frequency is modulated by a specific signal. It continuously transmits frequency-modulated signals to measure distance, velocity, and angle. Compared with other ranging and velocity measuring radars, FMCW radar has advantages such as simple structure, lower peak transmission power required, ease of modulation, low cost, and simple signal processing, and is therefore widely used.

[0003] Frequency-modulated continuous wave (FM-CVW) radar signal modulation primarily employs several different methods, including triangular wave modulation, sawtooth wave modulation, and sine wave modulation. Since sine wave modulation requires adjusting the signal frequency offset when detecting objects, it is mostly used when there is only one target. When it is necessary to detect information such as distance and velocity, and multiple targets need to be detected, triangular wave modulation and sawtooth wave modulation are often used. Sawtooth wave modulation is mainly used to measure the distance of an object, while triangular wave modulation can simultaneously obtain the distance and velocity information. Therefore, current FM-CVW radar primarily uses triangular wave modulation for signal modulation.

[0004] However, in practical applications, since the reflected beam used to calculate distance and velocity includes the optical Doppler frequency shift introduced by the motion of the target object, when using triangular wave modulation, the frequency shift caused by the Doppler effect is greater than the frequency shift caused by the flight time of the reflected beam when the target object is moving at high speed. This leads to errors (ambiguity) in the calculation of near-range information, resulting in measurement blind spots. In addition, the limitation of the frequency sweep period restricts the maximum frequency of the frequency-modulated continuous wave radar, affecting the target detection accuracy. Summary of the Invention

[0005] The purpose of this invention is to provide a target detection method, lidar, and device based on frequency-modulated continuous wave (FM-CW) to solve the problem of how to effectively improve the accuracy of target detection based on FM-CW.

[0006] To address the aforementioned technical problems, this invention provides a target detection method based on frequency-modulated continuous wave, comprising:

[0007] A probe wave is emitted to detect a target object, wherein one sweep cycle of the probe wave includes N sweep bands with different slopes, where N is a positive integer greater than or equal to 3;

[0008] Receive the echo of the probe wave after it is reflected off the target object;

[0009] Obtain the frequency sweep data corresponding to all frequency bands;

[0010] According to a preset method, m frequency sweep data are combined to obtain at least one frequency sweep array, where m is a positive integer greater than or equal to 3 and less than or equal to N;

[0011] Demodulate at least one set of frequency sweep arrays to obtain the distance and / or velocity of the target object.

[0012] Optionally, in the target detection method based on frequency-modulated continuous wave, the method of combining m frequency sweep data in a preset manner to obtain at least one set of frequency sweep arrays includes:

[0013] Combine the sweep data corresponding to the m sweep bands within the i-th sweep cycle to obtain a sweep array; and / or,

[0014] Combine the sweep data corresponding to the a sweep bands in the i-th sweep cycle and the sweep data corresponding to the ma sweep bands in the (i+1)-th sweep cycle to obtain a sweep array.

[0015] Where a is a positive integer greater than or equal to 1 and less than m, and i is a positive integer greater than or equal to 1.

[0016] Optionally, in the target detection method based on frequency-modulated continuous wave, the frequency bands corresponding to the m frequency sweep data in the same frequency sweep array are continuous.

[0017] Optionally, in the target detection method based on frequency-modulated continuous wave, the frequency sweep data includes the frequency sweep bandwidth, the beat signal frequency, and the frequency sweep slope; the method for demodulating at least one set of frequency sweep arrays to obtain the distance and / or velocity of the target object includes:

[0018] Use the sweep data corresponding to the sweep band with the smallest sweep bandwidth in the current sweep array as the judgment data, and use the other sweep data as the calculation data;

[0019] The echo delay and echo Doppler frequency shift are calculated using computational data. The calculation formula is as follows:

[0020]

[0021] Where f represents the frequency of the beat signal in the calculated data, and k represents the sweep band slope. Indicates echo delay, Indicates echo Doppler frequency shift;

[0022] The calculated echo delay and echo Doppler frequency shift are verified using the judgment data to obtain the final echo delay and echo Doppler frequency shift;

[0023] The distance and / or velocity of the target object are calculated based on the final determined echo delay and echo Doppler shift.

[0024] Optionally, in the target detection method based on frequency-modulated continuous wave, the sweep slope of the sweep frequency band corresponding to the judgment data is not 0.

[0025] Optionally, in the target detection method based on frequency-modulated continuous wave, after calculating the echo delay and echo Doppler frequency shift using computational data, the method for demodulating point cloud data using frequency sweep data further includes:

[0026] Remove the echo delay and its corresponding echo Doppler shift if the calculation result is negative;

[0027] The remaining echo delay and echo Doppler shift were verified using the judgment data.

[0028] Optionally, in the target detection method based on frequency-modulated continuous wave, the starting frequency of each frequency sweep in one sweep cycle of the probe wave is the same as the ending frequency of the previous frequency sweep.

[0029] To address the aforementioned technical problems, the present invention also provides a lidar for implementing the frequency-modulated continuous wave-based target detection method as described in any of the preceding claims, wherein the lidar comprises:

[0030] The transmitting module is used to transmit a probe wave to detect a target object, wherein one frequency sweep cycle of the probe wave includes N frequency sweep segments with different slopes, where N is a positive integer greater than or equal to 3;

[0031] The receiving module is used to receive the echo of the probe wave reflected on the target object and to acquire the sweep frequency data corresponding to all sweep frequency bands;

[0032] The processing module is used to combine m frequency sweep data in a preset manner to obtain at least one frequency sweep array, and demodulate at least one frequency sweep array to obtain the distance and / or speed of the target object, where m is a positive integer greater than or equal to 3 and less than or equal to N.

[0033] Optionally, in the aforementioned lidar, the transmitting module includes a space beam scanner.

[0034] To address the aforementioned technical problems, the present invention also provides a device comprising a lidar as described in any of the preceding claims.

[0035] The present invention provides a target detection method, lidar, and device based on frequency-modulated continuous wave (FMCV), comprising: emitting a probe wave to detect a target object, wherein one sweep cycle of the probe wave includes N sweep frequency bands with different slopes, where N is a positive integer greater than or equal to 3; receiving the echo of the probe wave reflected off the target object; acquiring sweep frequency data corresponding to all sweep frequency bands; combining m sweep frequency data according to a preset method to obtain at least one sweep frequency array, where m is a positive integer greater than or equal to 3 and less than or equal to N; and demodulating the at least one sweep frequency array to obtain the distance and / or velocity of the target object. By including multiple sweep frequency bands with different slopes in each sweep cycle of the probe wave and combining the sweep frequency data corresponding to the sweep frequency bands, the sweep frequency data can be reused during demodulation, thereby effectively improving the point cloud density per unit time; simultaneously, by independently demodulating and calculating the distance and / or velocity of the target object using multiple sweep frequency bands, the problem of ambiguity in the results can be effectively avoided. In this way, the problem of how to effectively improve the target detection accuracy based on frequency-modulated continuous wave was solved without adding extra hardware resources. Attached Figure Description

[0036] Figure 1 This is a flowchart of the target detection method based on frequency-modulated continuous wave provided in this embodiment;

[0037] Figure 2 This is a flowchart of step S5 in the frequency-modulated continuous wave-based target detection method provided in this embodiment;

[0038] Figure 3 This is a schematic diagram of the waveform of the probe wave provided in this embodiment;

[0039] Figure 4 This is a schematic diagram of the swept bandwidth of the probe wave provided in this embodiment;

[0040] Figure 5 This is a schematic diagram of the lidar structure provided in this embodiment. Detailed Implementation

[0041] The target detection method, lidar, and device based on frequency-modulated continuous wave proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise scales, used only to facilitate and clarify the illustration of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales.

[0042] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this invention are used to distinguish similar objects in order to describe embodiments of the invention, and are not used to describe a specific order or sequence. It should be understood that such uses of terminology are interchangeable where appropriate. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] This embodiment provides a target detection method based on frequency-modulated continuous wave, such as... Figure 1 As shown, it includes:

[0044] S1, a probe wave is emitted to detect the target object, wherein one sweep cycle of the probe wave includes N sweep frequency bands with different slopes, where N is a positive integer greater than or equal to 3;

[0045] S2, receives the echo of the probe wave reflected off the target object;

[0046] S3, obtain the frequency sweep data corresponding to all frequency sweep bands;

[0047] S4. Combine m frequency sweep data according to a preset method to obtain at least one frequency sweep array, where m is a positive integer greater than or equal to 3 and less than or equal to N;

[0048] S5, demodulate at least one set of sweep frequency arrays to obtain the distance and / or velocity of the target object.

[0049] The frequency-modulated continuous wave (FM-CVT) target detection method provided in this embodiment includes multiple frequency bands with different slopes in each frequency sweep cycle of the probe wave, and combines the frequency sweep data corresponding to the frequency bands. This allows for the reuse of the frequency sweep data during demodulation, effectively improving the point cloud density per unit time. Simultaneously, by independently demodulating and calculating the distance and / or velocity of the target object using multiple frequency bands, the problem of de-ambiguity can be effectively avoided. Thus, without increasing hardware resources, the problem of effectively improving the accuracy of FM-CVT-based target detection is solved.

[0050] Specifically, in this embodiment, step S1 involves emitting a probe wave to detect the target object.

[0051] In this process, a single sweep period T of the probe wave consists of N sweep segments with different slopes, where N is a positive integer greater than or equal to 3. Taking N=3 as an example, in one sweep period, the first sweep segment has a sweep slope of k1 and a duration of t1; the second sweep segment has a sweep slope of k2 and a duration of t2; the third sweep segment has a sweep slope of k3 and a duration of t3; therefore, T=t1+t2+t3.

[0052] Of course, in other embodiments, the number of frequency bands in a single frequency sweep cycle can be flexibly set according to actual needs, and this application does not impose any restrictions on this.

[0053] Preferably, in practical applications, within one sweep cycle of the probe wave, the starting frequency of each sweep band is the same as the ending frequency of the previous sweep band, thereby ensuring the continuity of the probe wave signal. Of course, in practical applications, the starting frequency of a sweep cycle can also be the same as its ending frequency, thus ensuring the continuity of the probe wave signal when multiple sweep cycles are transmitted. Of course, in other embodiments, the beginning and ending frequencies of a sweep band can also be discontinuous.

[0054] Furthermore, in this embodiment, in one sweep cycle of the probe wave, the sweep slope of any segment of the N sweep bands can be 0, thereby making the sweep band unmodulated. This is beneficial for accurately calculating the Doppler frequency shift introduced by the motion of the target object, and solves the defect of ambiguity in the calculated distance and velocity when using triangular wave modulation in the prior art and demodulating with only two sweep slopes in a single sweep cycle.

[0055] Furthermore, in this embodiment, step S2 involves receiving the echo of the probe wave reflected off the target object.

[0056] Specifically, steps S1 and S2 are both implemented by lidar, and their specific implementation process is well known to those skilled in the art, and will not be described in detail here.

[0057] Furthermore, in this embodiment, step S3 involves acquiring the sweep frequency data corresponding to all sweep frequency bands.

[0058] In this embodiment, frequency sweep data can be obtained from the transmitted probe wave and the received echo through signal processing, calculation, and other processes. The frequency sweep data includes, but is not limited to, the frequency sweep bandwidth. The frequency f of the sweep signal and the slope k of the sweep band.

[0059] Specifically, taking N=3 as an example, the sweep bandwidth of the first sweep segment in the i-th sweep cycle is denoted as... The frequency of the shooting signal is denoted as The sweep slope is denoted as . The sweep bandwidth of the second sweep band is denoted as... The frequency of the shooting signal is denoted as The sweep slope is denoted as . The sweep bandwidth of the third sweep band is denoted as... The frequency of the shooting signal is denoted as The sweep slope is denoted as . Of course, those skilled in the art can understand the representation of each frequency band when N takes other values ​​according to the above representation, and this application will not elaborate on this further.

[0060] Furthermore, in this embodiment, in step S4, the m sweep frequency data are combined in a preset manner to obtain at least one sweep frequency array.

[0061] Method 1: Combine the sweep data corresponding to the m sweep bands in the i-th sweep cycle to obtain a sweep array, where m is a positive integer greater than or equal to 3 and less than or equal to N.

[0062] Specifically, taking the example of N being 3, m is also 3. That is, the frequency sweep data corresponding to the frequency sweep band in the same scan cycle is used as a set of frequency sweep arrays.

[0063] Alternatively, in method two, the sweep data corresponding to the a sweep bands in the i-th sweep cycle and the sweep data corresponding to the ma sweep bands in the (i+1)-th sweep cycle are combined to obtain a sweep array, where m is a positive integer greater than or equal to 3 and less than or equal to N, a is a positive integer greater than or equal to 1 and less than m, and i is a positive integer greater than or equal to 1.

[0064] Specifically, taking N as an example of 3, m is also 3, and a can be 1 or 2. When a is 1, the sweep data corresponding to one sweep band in the i-th period and the sweep data corresponding to two sweep bands in the (i+1)-th period are combined into a sweep array; when a is 2, the sweep data corresponding to two sweep bands in the i-th period and the sweep data corresponding to one sweep band in the (i+1)-th period are combined into a sweep array.

[0065] Of course, in practical applications, the values ​​of m and a can be reasonably set according to the value of N and actual needs, and this application does not impose any restrictions on this.

[0066] Furthermore, in practical applications, to obtain more accurate calculation results, the frequency bands corresponding to the m frequency sweep data in the same frequency sweep array are continuous. That is, when the m frequency sweep data in the i-th frequency sweep cycle are used as a single frequency sweep array, the frequency bands corresponding to the m frequency sweep data are sequentially continuous; when the a frequency sweep data in the i-th frequency sweep cycle and the ma frequency sweep data in the (i+1)-th frequency sweep cycle are used as a single frequency sweep array, the frequency bands corresponding to the a frequency sweep data in the i-th frequency sweep cycle and the frequency bands corresponding to the ma frequency sweep data in the (i+1)-th frequency sweep cycle are sequentially continuous. For example, when a is 1, the frequency sweep data corresponding to the third frequency sweep in the i-th cycle and the frequency sweep data corresponding to the first and second frequency sweeps in the (i+1)-th cycle are used as a single frequency sweep array.

[0067] Furthermore, in practical applications, the combination of sweep arrays shown in Method 1 can be used to combine the sweep data for all sweep cycles, or the combination of sweep arrays shown in Method 2 can be used to combine the sweep data for all sweep cycles. Alternatively, both the combination methods shown in Method 1 and Method 2 can be used simultaneously to combine the sweep data for all sweep cycles, thereby achieving data reuse, increasing the point cloud density per unit time, and thus solving the problem of how to effectively improve the target detection accuracy based on frequency-modulated continuous waves without increasing hardware resources.

[0068] Furthermore, in this embodiment, as Figure 2 As shown, step S5, the method for demodulating at least one set of swept frequency arrays to obtain the distance and / or velocity of the target object includes:

[0069] S51: The sweep frequency data corresponding to the sweep frequency band with the smallest sweep frequency bandwidth in the current sweep frequency array is used as the judgment data, and the other sweep frequency data is used as the calculation data. Since a small sweep frequency bandwidth is not conducive to improving calculation accuracy, using the sweep frequency data corresponding to the sweep frequency band with the smallest sweep frequency bandwidth as the judgment data and the other sweep frequency data as the calculation data can improve the target detection accuracy to a certain extent.

[0070] Taking N as an example of 3, and using the point cloud data demodulation method of Method 1, that is, using three frequency bands in the same frequency sweep cycle as a group of frequency sweep data for point cloud data demodulation calculation. Here, it is assumed that the second frequency band is the one with the smallest frequency sweep bandwidth among the three frequency bands. Therefore, the frequency sweep data corresponding to the second frequency band is used as the judgment data, and the first and third frequency bands are used as the calculation data.

[0071] S52, using computational data, calculates the echo delay and echo Doppler frequency shift, where the calculation formula is:

[0072]

[0073] Where f represents the frequency of the beat signal in the calculated data, and k represents the sweep band slope. Indicates echo delay, This indicates the echo Doppler frequency shift.

[0074] Since each sweep band satisfies the above formula, the beat signal frequency of the three sweep bands can be expressed as:

[0075]

[0076]

[0077]

[0078] Using the calculated data, specifically the calculation formulas corresponding to the first and second frequency sweeps, the following four sets of echo delays can be obtained. echo Doppler frequency shift Calculation results:

[0079] Group 1: , ;

[0080] Group 2: , ;

[0081] Group 3: , ;

[0082] Group 4: , ;

[0083] S53, the calculated echo delay and echo Doppler frequency shift are verified using the judgment data to obtain the final echo delay and echo Doppler frequency shift.

[0084] Specifically, considering that the echo delay is positive and the beat signal frequency of each sweep band is also positive, the echo delay and its corresponding echo Doppler frequency shift that have negative calculation results are removed. The remaining echo delay and echo Doppler frequency shift are then substituted into the formula corresponding to the judgment data for judgment. The combination of echo delay and echo Doppler frequency shift that meets the equality criterion is taken as the correct final solution.

[0085] Using the example above, after removing the negative echo delay and its corresponding echo Doppler shift, the remaining echo delay and echo Doppler shift are then substituted into... Verification was performed to confirm whether the calculation results matched the frequency sweep data of the second frequency sweep band, in order to confirm the final echo delay and echo Doppler frequency shift.

[0086] Preferably, considering that the above formula needs to be used to determine the final echo delay and echo Doppler frequency shift using the judgment data, in practical applications, in addition to using the sweep data corresponding to the sweep band with the smallest sweep bandwidth as the judgment data, the sweep slope of the sweep band corresponding to the sweep data used as the judgment data can also be selected to be non-zero, so as to ensure the validity of the judgment result.

[0087] S54, the distance and / or velocity of the target object are calculated based on the finally determined echo delay and echo Doppler frequency shift. The method of calculating the distance and / or velocity of the target object based on the echo delay and echo Doppler frequency shift is well known to those skilled in the art, and will not be described in detail here.

[0088] The method for demodulating point cloud data using the combination of frequency sweep arrays in Method Two is similar to the method for demodulating point cloud data using the combination of frequency sweep arrays in Method One, and will not be described again in this application. Furthermore, those skilled in the art can understand the calculation methods for demodulating point cloud data in other situations based on the calculation method for demodulating point cloud data provided in this embodiment, and will not be described again in this application.

[0089] The following is a specific embodiment illustrating the demodulation of the probe wave and the echo in the target detection method based on frequency-modulated continuous wave provided in this application.

[0090] In this embodiment, such as Figure 3 As shown, each sweep cycle of the probe wave has three sweep segments with different slopes. Within a single sweep cycle, the first sweep segment has a sweep slope of k1 and a duration of t1; the second sweep segment has a sweep slope of k2 and a duration of t2; and the third sweep segment has a sweep slope of k3 and a duration of t3. The sweep cycle T = t1 + t2 + t3. Within each sweep cycle, the frequencies of the sweep segments are continuous, meaning that the starting frequency of each sweep segment is the same as the ending frequency of the previous sweep segment; and the starting frequency of the sweep cycle is the same as the ending frequency of the previous sweep cycle.

[0091] Three combination modes were used when obtaining the frequency sweep array:

[0092] Combination Mode 1 (corresponding to Method 1): The sweep data corresponding to the 3 sweep bands in the i-th sweep cycle are used as a sweep array;

[0093] Combination Mode 2 (corresponding to Method 2): The sweep frequency data corresponding to the last two sweep frequency bands in the i-th sweep frequency cycle and the sweep frequency data corresponding to the first sweep frequency band in the (i+1)-th sweep frequency cycle are used as a sweep frequency array;

[0094] Combination Mode 3 (corresponding to Mode 2): The sweep frequency data corresponding to the last sweep frequency band in the i-th sweep frequency cycle and the sweep frequency data corresponding to the first two sweep frequency bands in the (i+1)-th sweep frequency cycle are used as a sweep frequency array.

[0095] The point cloud data demodulation method for the swept frequency arrays obtained by the three combination modes is the same. Assuming that the second swept frequency band has the smallest swept frequency bandwidth, such as... Figure 4 As shown, the frequency sweep data corresponding to the second frequency sweep segment is used as the judgment data, and the first and third frequency sweep segments are used as the calculation data.

[0096] Specifically, for combination pattern one, we have:

[0097]

[0098]

[0099]

[0100] Due to the frequency of the shooting signal , and The sweep slope can be measured. , and It is also known that, using the above formula, four possible combinations of echo delay and echo Doppler frequency shift can be calculated.

[0101] Subsequently, due to the frequency of the shooting signal , and and echo delay Since all values ​​are positive, echo delays that meet the criteria can be selected. echo Doppler frequency shift Next, the echo that meets the conditions is delayed. echo Doppler frequency shift Substitute the values ​​into the formula for the second frequency sweep and use it to make a judgment. The combination of echo delay and echo Doppler frequency shift that meets the equality criterion is taken as the correct final solution.

[0102] Thus, by combining mode one, a point cloud point information can be calculated.

[0103] Similarly, for combination pattern two, we have:

[0104]

[0105]

[0106]

[0107] Due to the frequency of the shooting signal , and The sweep slope can be measured. , and It is also known that, using the above formula, four possible combinations of echo delay and echo Doppler frequency shift can be calculated.

[0108] Subsequently, due to the frequency of the shooting signal , and and echo delay Since all values ​​are positive, echo delays that meet the criteria can be selected. echo Doppler frequency shift Next, the echo that meets the conditions is delayed. echo Doppler frequency shift Substitute the values ​​into the formula for the second frequency sweep and use it to make a judgment. The combination of echo delay and echo Doppler frequency shift that meets the equality criterion is taken as the correct final solution.

[0109] Thus, by using combination mode two, an additional point cloud point information can be calculated.

[0110] Similarly, for combination pattern three, we have:

[0111]

[0112]

[0113]

[0114] Due to the frequency of the shooting signal , and The sweep slope can be measured. , and It is also known that, using the above formula, four possible combinations of echo delay and echo Doppler frequency shift can be calculated.

[0115] Subsequently, due to the frequency of the shooting signal , and and echo delay Since all values ​​are positive, echo delays that meet the criteria can be selected. echo Doppler frequency shift Next, the echo that meets the conditions is delayed. echo Doppler frequency shift Substitute the values ​​into the formula for the second frequency sweep and use it to make a judgment. The combination of echo delay and echo Doppler frequency shift that meets the equality criterion is taken as the correct final solution.

[0116] Thus, by using combination mode three, an additional point cloud point information can be calculated.

[0117] The frequency-modulated continuous wave (FM-CVT)-based target detection method provided in this embodiment employs three combination modes to reuse the sweep data corresponding to each sweep band. This allows for the calculation of a point cloud information under each combination mode, thereby increasing the point cloud density by three times per unit time. Of course, if the number of sweep bands in a single sweep cycle is greater, the number of sweep bands used for point cloud data demodulation is greater, and the number of combination modes is greater, the point cloud density per unit time can be further increased, thus effectively improving the target detection accuracy based on FM-CVT.

[0118] The target detection method based on frequency-modulated continuous wave provided in this embodiment can significantly improve point cloud density without additional hardware resources. If the same point frequency needs to be maintained, hardware resources can be reduced, such as reducing the number of hardware channels, thereby reducing costs.

[0119] The target detection method based on frequency-modulated continuous wave provided in this embodiment can generate a more refined point cloud by simply changing the waveform of the probe wave, without changing the field of view and speed of the existing radar scanner, thereby improving the radar's perception level.

[0120] This embodiment also provides a lidar for implementing the frequency-modulated continuous wave-based target detection method described above, such as... Figure 5 As shown, the lidar includes:

[0121] The transmitting module is used to transmit a probe wave to detect a target object, wherein one frequency sweep cycle of the probe wave includes N frequency sweep segments with different slopes, where N is a positive integer greater than or equal to 3;

[0122] The receiving module is used to receive the echo of the probe wave reflected on the target object and to acquire the sweep frequency data corresponding to all sweep frequency bands;

[0123] The processing module is used to combine m frequency sweep data in a preset manner to obtain at least one frequency sweep array, and demodulate at least one frequency sweep array to obtain the distance and / or speed of the target object, where m is a positive integer greater than or equal to 3 and less than or equal to N.

[0124] Specifically, in practical applications, the lidar is a frequency modulated continuous wave radar (FMCW radar). The specific structure and function of frequency modulated continuous wave radar are well known to those skilled in the art, and will not be described in detail here.

[0125] Preferably, in this embodiment, the transmitting module includes a space beam scanner. By controlling the scanning direction and angle of the laser beam through the space beam scanner, it can be ensured that the lidar can scan the surrounding environment in all directions (360 degrees), thereby achieving accurate perception and ranging of the surrounding environment.

[0126] Furthermore, this embodiment also provides a device including the lidar described above.

[0127] Specifically, in practical applications, the equipment can be used for various large and small-to-medium-sized devices that require LiDAR, such as automobiles, robots, and airplanes.

[0128] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In addition, different parts between embodiments can also be combined with each other, and this invention does not limit this.

[0129] This embodiment provides a target detection method, lidar, and device based on frequency-modulated continuous wave (FMCH), comprising: emitting a probe wave to detect a target object, wherein one sweep cycle of the probe wave includes N sweep frequency bands with different slopes, where N is a positive integer greater than or equal to 3; receiving the echo of the probe wave reflected off the target object; acquiring sweep frequency data corresponding to all sweep frequency bands; combining m sweep frequency data according to a preset method to obtain at least one sweep frequency array, where m is a positive integer greater than or equal to 3 and less than or equal to N; and demodulating the at least one sweep frequency array to obtain the distance and / or velocity of the target object. By including multiple sweep frequency bands with different slopes in each sweep cycle of the probe wave and combining the sweep frequency data corresponding to the sweep frequency bands, the sweep frequency data can be reused during demodulation, thereby effectively improving the point cloud density per unit time; simultaneously, using multiple sweep frequency bands to independently demodulate and calculate the distance and / or velocity of the target object effectively avoids the problem of ambiguity in the results. In this way, the problem of how to effectively improve the target detection accuracy based on frequency-modulated continuous wave was solved without adding extra hardware resources.

[0130] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A target detection method based on frequency-modulated continuous wave, characterized in that, include: A probe wave is emitted to detect a target object, wherein one sweep cycle of the probe wave includes N sweep bands with different slopes, where N is a positive integer greater than or equal to 3; Receive the echo of the probe wave after it is reflected off the target object; Obtain the frequency sweep data corresponding to all frequency bands; According to a preset method, m frequency sweep data are combined to obtain multiple frequency sweep arrays, including: combining the frequency sweep data corresponding to the m frequency sweeps in the i-th frequency sweep period to obtain a frequency sweep array; and / or, combining the frequency sweep data corresponding to the a frequency sweeps in the i-th frequency sweep period and the frequency sweep data corresponding to the ma frequency sweeps in the (i+1)-th frequency sweep period to obtain a frequency sweep array; the frequency sweeps corresponding to the m frequency sweep data in the same frequency sweep array are consecutive; where m is a positive integer greater than or equal to 3 and less than or equal to N, a is a positive integer greater than or equal to 1 and less than m, and i is a positive integer greater than or equal to 1; Demodulate multiple sets of frequency sweep arrays to obtain the distance and / or velocity of the target object.

2. The target detection method based on frequency-modulated continuous wave according to claim 1, characterized in that, The frequency sweep data includes the frequency sweep bandwidth, the beat signal frequency, and the frequency sweep slope; the method for demodulating multiple sets of frequency sweep arrays to obtain the distance and / or velocity of the target object includes: Use the sweep data corresponding to the sweep band with the smallest sweep bandwidth in the current sweep array as the judgment data, and use the other sweep data as the calculation data; The echo delay and echo Doppler frequency shift are calculated using computational data. The calculation formula is as follows: Where f represents the frequency of the beat signal in the calculated data, and k represents the sweep band slope. Indicates echo delay. Indicates echo Doppler frequency shift; The calculated echo delay and echo Doppler frequency shift are verified using the judgment data to obtain the final echo delay and echo Doppler frequency shift; The distance and / or velocity of the target object are calculated based on the final determined echo delay and echo Doppler shift.

3. The target detection method based on frequency-modulated continuous wave according to claim 2, characterized in that, The sweep slope of the sweep band corresponding to the judgment data is not 0.

4. The target detection method based on frequency-modulated continuous wave according to claim 2, characterized in that, After calculating the echo delay and echo Doppler frequency shift using computational data, methods for demodulating point cloud data using swept frequency data also include: Remove the echo delay and its corresponding echo Doppler shift if the calculation result is negative; The remaining echo delay and echo Doppler shift were verified using the judgment data.

5. The target detection method based on frequency-modulated continuous wave according to claim 1, characterized in that, In one sweep cycle of the probe wave, the starting frequency of each sweep band is the same as the ending frequency of the previous sweep band.

6. A lidar for implementing the frequency-modulated continuous wave-based target detection method as described in any one of claims 1 to 5, characterized in that, The lidar includes: The transmitting module is used to transmit a probe wave to detect a target object, wherein one frequency sweep cycle of the probe wave includes N frequency sweep segments with different slopes, where N is a positive integer greater than or equal to 3; The receiving module is used to receive the echo of the probe wave reflected on the target object and to acquire the sweep frequency data corresponding to all sweep frequency bands; The processing module is used to combine m frequency sweep data according to a preset method to obtain multiple frequency sweep arrays, and demodulate the multiple frequency sweep arrays to obtain the distance and / or velocity of the target object, where m is a positive integer greater than or equal to 3 and less than or equal to N.

7. The lidar according to claim 6, characterized in that, The transmitting module includes a space beam scanner.

8. A target detection device, characterized in that, Including the lidar as described in any one of claims 6 to 7.

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