Laser radar detection method and laser radar

Abstract

The invention discloses a laser radar detection method and a laser radar, and the method comprises the steps: providing a group of detection optical signals, and enabling the detection optical signals to be transmitted to a detection space, and enabling the group of detection optical signals to comprise two optical signals with different frequency change trend directions; receiving echo signals corresponding to the group of detection optical signals, and performing frequency beating on the echo signals and local oscillation optical signals of two optical signals with different frequency change trend directions in the group of detection optical signals to determine a corresponding first beat frequency signal and a corresponding second beat frequency signal; the first beat frequency signal is converted into a first electric signal, and the second beat frequency signal is converted into a second electric signal; synchronous data acquisition is carried out on the first electric signal and the second electric signal, so that a plurality of difference frequency signal pairs are obtained in the same modulation period, and each difference frequency signal pair comprises a corresponding first difference frequency signal and a corresponding second difference frequency signal; and determining object information in the detection space according to the first difference frequency signal and the second difference frequency signal corresponding to each difference frequency signal pair.

Description

Technical Field

[0001] This application relates to the field of laser technology, and in particular, to a lidar detection method and a lidar. Background Art

[0002] Currently, when a frequency-modulated continuous-wave lidar performs data calculation, it needs to collect a complete modulation period. Therefore, it is required that the measurement point frequency be consistent with the modulation frequency. That is to say, the modulation frequency determines the measurement point frequency. To increase the point frequency, the modulation frequency must be increased. However, since light also has a certain flight time, if the modulation frequency is too high, the flight time of the detection beam is greater than the period duration of the modulation period, which will cause the detection signal of this period and the local oscillator signal of this period to be unable to perform beat frequency, resulting in an incorrect detection result. Considering the quality of the beat frequency signal, the effective beat frequency time needs to be increased, then the modulation frequency needs to be decreased, and the point frequency also needs to be decreased.

[0003] It can be seen that in the lidar detection method in the related art, there is a problem of low target detection efficiency of the lidar. Summary of the Invention

[0004] An embodiment of this application provides a lidar detection method and a lidar to at least solve the problem of low target detection efficiency of the lidar in the lidar detection method in the related art.

[0005] According to one aspect of the embodiments of this application, a lidar detection method is provided, including: providing a set of detection optical signals and emitting them into a detection space, where the set of detection optical signals includes two optical signals with different frequency change trend directions; receiving echo signals corresponding to the set of detection optical signals, and respectively performing beat frequency on the echo signals and the local oscillator optical signals of the two optical signals with different frequency change trend directions in the set of detection optical signals to determine corresponding first beat frequency signals and second beat frequency signals; and converting the first beat frequency signal into a first electrical signal and converting the second beat frequency signal into a second electrical signal; synchronously collecting data on the first electrical signal and the second electrical signal to obtain multiple difference frequency signal pairs within the same modulation period, where the difference frequency signal pair includes a corresponding first difference frequency signal and a second difference frequency signal; and determining object information in the detection space according to the first difference frequency signal and the second difference frequency signal corresponding to each difference frequency signal pair.

[0006] According to another aspect of the embodiments of the present application, there is also provided a lidar, including: a light source for providing a set of detection optical signals, wherein the set of detection optical signals includes two optical signals with different frequency change trend directions; a scanning component for respectively emitting the set of detection optical signals into a detection space; a receiving module for receiving echo signals corresponding to the set of detection optical signals, and respectively performing beat frequency on the echo signals and local oscillator optical signals of two optical signals with different frequency change trend directions in the set of detection optical signals to determine a first beat frequency signal and a second beat frequency signal corresponding to the set of detection optical signals; and converting the first beat frequency signal into a first electrical signal and converting the second beat frequency signal into a second electrical signal; a data acquisition module electrically connected to the receiving module for synchronously acquiring data on the first electrical signal and the second electrical signal to obtain multiple sets of corresponding first difference frequency signals and second difference frequency signals within the same modulation period; a data processing module electrically connected to the data acquisition module for determining object information in the detection space according to the corresponding first difference frequency signal and second difference frequency signal.

[0007] In the embodiments of the present application, a method of acquiring data on beat frequency signals corresponding to two detection optical signals with different frequency change trend directions within the same modulation period is adopted. Since a set of detection optical signals includes two optical signals with different frequency change trend directions, two modulation signals with different frequency change trend directions can be obtained within the same modulation period, that is, there are two modulation signals with different frequency change trend directions at each moment during the beat frequency time of the same modulation period. It is not necessary to acquire a complete period to perform data calculation and determine object information in the detection space. Thus, the point frequency size can be flexibly controlled by adjusting the sampling time, avoiding the measurement point frequency being limited by the detection range, and further solving the problem of low target detection efficiency of lidar in the related art of lidar detection methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0009] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0010] Figure 1 It is a schematic flowchart of an embodiment of an optional lidar detection method according to the embodiments of the present application;

[0011] Figure 2 It is a schematic diagram of an embodiment of an optional lidar detection method according to an embodiment of the present application;

[0012] Figure 3 It is a schematic diagram of an embodiment of another optional lidar detection method according to an embodiment of the present application;

[0013] Figure 4 It is a schematic diagram of an embodiment of yet another optional lidar detection method according to an embodiment of the present application;

[0014] Figure 5 It is a schematic diagram of an embodiment of an optional lidar according to an embodiment of the present application;

[0015] Figure 6 It is a partial schematic diagram of an optional lidar according to an embodiment of the present application;

[0016] Figure 7 It is a partial schematic diagram of another optional lidar according to an embodiment of the present application. Detailed implementation manners

[0017] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0018] According to one aspect of the embodiments of the present application, a lidar detection method is provided. As an optional exemplary embodiment, in this embodiment, as Figure 1 shown, Figure 1 It is a schematic flowchart of an embodiment of an optional lidar detection method according to an embodiment of the present application. As Figure 1 shown, the process of this method may include the following steps.

[0019] Step S102: Provide a set of detection optical signals and emit them into the detection space, where a set of detection optical signals includes two optical signals with different frequency change trend directions.

[0020] The lidar detection method in this embodiment can be applied to scenarios where lidar is used for target detection. The lidar can include, but is not limited to, Frequency Modulated Continuous Wave (FMCW) lidar. FMCW lidar uses laser as a sensor to emit a continuous wave laser beam and changes the frequency of the laser through frequency modulation. When the laser beam irradiates the surface of the target object, part of the laser is reflected back by the target object. The lidar receives the reflected laser signal and calculates the distance between the detection target and the lidar by detecting the frequency change of the laser.

[0021] In current FMCW lidars, when performing data calculation, a complete modulation period needs to be collected. In this way, the measured point frequency is consistent with the modulation frequency. That is to say, the modulation frequency determines the measurement point frequency. To increase the point frequency, the modulation frequency must be increased. However, due to the fact that light has a certain flight time, if the modulation frequency is too high and the flight time of the ranging light is greater than the modulation period, the ranging signal of this period and the local oscillator signal of this period cannot be beat, resulting in an incorrect ranging result. Therefore, the modulation frequency cannot be further increased. If the ranging range is calculated as 300m, the flight time of the ranging light is 2us. If the unilateral beat time is not less than 0.5us, the maximum modulation frequency is 200kHz. Considering the quality of the beat signal, the effective beat time needs to be increased, so the modulation frequency needs to be decreased, and the point frequency also needs to be decreased. This introduces a contradiction between the point frequency and the ranging range. In addition, as the distance increases, the invalid beat time will increase, and the signals during this time cannot be used, resulting in a low time utilization rate within one period.

[0022] To at least partially solve the above technical problems, this application proposes a system solution that decouples the point frequency and the modulation frequency. By providing two optical signals with different frequency change trend directions by the lidar, within the same data acquisition period, two modulation signals with different frequency change trends can be obtained, solving the contradiction between the point frequency and the ranging range and increasing the time utilization rate. Here, decoupling means that the data of the entire modulation period does not need to be collected for each calculation; since there are two modulation signals with different frequency change trend directions at least for part of the time within one modulation period, data calculation can be performed without collecting a complete period. In this way, the modulation frequency can be appropriately decreased, and thus the problem of low target detection efficiency of the lidar in the related art can be solved.

[0023] LiDAR systems typically use semiconductor lasers or solid-state lasers as the light source. These lasers can generate laser beams with high intensity, monochromaticity, and good directivity, which are used to measure information such as the distance, speed, and shape of the target object. In this embodiment, a set of detection optical signals provided by the LiDAR, which contains two optical signals with different frequency change trend directions, is emitted into the detection space. When there is an object in the detection space, the LiDAR can receive the echo signals corresponding to each detection optical signal in the set of detection optical signals reflected by the object in the detection space.

[0024] In an exemplary embodiment, the LiDAR includes a first laser and a second laser. Among them, the first laser is used to provide a first optical signal, and the second laser is used to provide a second optical signal. The frequency change trend directions of the first optical signal and the second optical signal are different, constituting a set of detection optical signals.

[0025] Here, the frequency change trend of the optical signal can refer to the change trend of the frequency of the laser signal over time, which can be a periodic increase, a periodic decrease, remaining unchanged, etc. This embodiment does not limit this.

[0026] For example, in an exemplary embodiment, the two optical signals included in a set of detection optical signals have the same slope magnitude and opposite slope change trend directions; or, one of the two optical signals included in a set of detection optical signals is a fixed-frequency signal, and the other optical signal is a triangular wave signal.

[0027] Here, the fixed-frequency signal means that the frequency of the signal remains constant, that is, the frequency of the optical signal does not change with time and remains at a fixed value. The triangular wave signal is a signal with a specific shape, and its waveform shows a change similar to a triangle.

[0028] In an exemplary embodiment, before providing a set of detection optical signals and emitting them into the detection space, the above method further includes:

[0029] Providing a first initial signal through the first laser and modulating the first initial signal into a first optical signal through a first modulation module; and

[0030] Obtaining a second initial signal through the second laser and modulating the second initial signal into a second optical signal through a second modulation module.

[0031] In this embodiment, the modulation module can modulate the laser signal to achieve some specific functions or obtain more information. The modulation module can change specific parameters of the laser signal, such as frequency, amplitude, phase, etc., so as to be able to achieve some specific signal processing or measurement functions. Common modulators include pulse modulators, frequency modulators, and phase modulators.

[0032] To achieve different directions of the frequency change trends of two detection signals, two lasers with different wavelengths can be used for in-phase modulation, or one can be modulated while the other is not modulated. The modulation scheme can be internal modulation or external modulation. Here, in-phase modulation means that the phases of the two modulation signals differ by 180 degrees; internal modulation means directly modulating the excitation current of the laser inside the laser, and changing the characteristics of the laser signal, such as frequency, amplitude, etc. by changing the excitation current of the laser; external modulation means modulating the laser signal through an external optical modulator after the laser signal output by the laser.

[0033] Here, the modulation slope of the laser refers to the slope of the optical frequency output by the laser changing with the modulation signal. In this embodiment, the modulation slopes of the two lasers can be different or the same, and this embodiment does not limit this.

[0034] Step S104, receiving the echo signals corresponding to a group of detection optical signals, and respectively performing beat frequency with the local oscillator optical signals of two optical signals with different directions of the frequency change trends in the group of detection optical signals to determine the corresponding first beat frequency signal and second beat frequency signal; and converting the first beat frequency signal into a first electrical signal and converting the second beat frequency signal into a second electrical signal.

[0035] Here, the local oscillator light is a part of the optical signal containing the modulation signal, and the reflected light refers to the light beam that returns to the lidar receiver after the laser signal interacts with the detection target. By measuring the beat frequency and its intensity of the reflected light and the local oscillator light, the lidar can determine information such as the distance, speed, shape, and surface characteristics of the target object.

[0036] The beat frequency signal can refer to the signal generated by the frequency difference between the reflected signal (echo signal) received by the lidar system and the local reference signal (local oscillator optical signal). Taking a triangular wave modulation signal as an example, as Figure 2 shown, the solid line represents the transmitted signal (local oscillator signal), the dashed line represents the received reflected signal (echo signal), and the frequency difference between the two generates the beat frequency signal.

[0037] For example, in an exemplary embodiment, the echo signal includes a first echo signal and a second echo signal;

[0038] Respectively performing beat frequency with the local oscillator optical signals of two optical signals with different directions of the frequency change trends in the group of detection optical signals to determine the corresponding first beat frequency signal and second beat frequency signal includes:

[0039] The first echo signal and the corresponding first local oscillator optical signal are beat to obtain a first beat signal through a first receiving module, and the second echo signal and the corresponding second local oscillator optical signal are beat to obtain a second beat signal through a second receiving module.

[0040] When a laser beam irradiates a detection target, there will be a frequency difference between the frequency of the reflected optical signal and the frequency of the local oscillator signal, and this frequency difference is the beat frequency. In a lidar system, the echo signal and a part of the transmitted signal (detection optical signal) are coherently mixed to obtain a beat signal containing the distance and velocity information of the detection target, and then the beat signal is detected to obtain the distance and velocity of the detection target.

[0041] For the echo signals corresponding to each of the two detection signals reflected by the detection target within a specified space, the local oscillator signal corresponding to each detection signal and the echo signal corresponding to each detection signal are respectively beat to obtain two beat signals.

[0042] Here, the purpose of converting the beat signal into an electrical signal is to enable further processing and analysis of the beat signal. After converting the beat signal into an electrical signal, operations such as signal processing, filtering, and amplification can be performed using electronic devices to extract information such as the velocity and movement direction of the target object. Converting the beat signal into an electrical signal also enables the signal to be digitized and processed and analyzed by a computer or other digital processing devices, which is very important for data acquisition. Combining Figure 3 , in a lidar system, an LD (Laser Diode) is used to generate a laser beam, and a PD (Photodiode) is used to receive the reflected signal (echo signal) of the laser beam and convert it into an electrical signal.

[0043] Step S106, synchronously collect data on the first electrical signal and the second electrical signal to obtain multiple difference frequency signal pairs within the same modulation period, where a difference frequency signal pair includes a corresponding first difference frequency signal and a second difference frequency signal.

[0044] Here, the difference frequency signal refers to the frequency difference between the laser signal transmitted by the lidar and the received echo signal. This frequency difference can be used to further analyze information such as the velocity and shape of the target object. For example, if the lidar transmits a laser signal at a frequency f1 and the frequency of the received echo signal is f2, then the difference frequency signal is f2 - f1. By analyzing the frequency change of the difference frequency signal, information such as the distance, velocity, and shape of the target object can be further understood, where at least one frame of data is required to determine the shape.

[0045] Currently, by obtaining the frequency of the beat frequency signal, the distance and speed information of the target object can be calculated. Based on this, taking the triangular wave modulation signal as an example, in order to obtain the difference frequency signal, it is usually necessary to collect a complete modulation period. In this embodiment, since there are modulation signals with different frequency change trend directions at least during part of the same modulation period, it is not necessary to collect a complete period to perform data resolution. Based on the obtained data sampling results, the object information in the detection space can be determined, and thus the modulation frequency can be appropriately reduced.

[0046] Optionally, the object information in the detection space may include, but is not limited to, information such as the distance, speed, and angle of the target object in the detection space.

[0047] By adjusting the sampling time, the point frequency can be flexibly controlled. By adjusting the modulation speed and modulation bandwidth, different precisions and ranges can be achieved. In this embodiment, after the radar collects the signals for a period of time (this period is very short, generally several microseconds), the distance and speed information of the object within this period can be calculated, and thus a detection is obtained, and a coordinate point can be displayed on the point cloud. Generally, the number of detections of the radar within 1 s is the point frequency, which is an important index of the lidar. In this scheme, the sampling interval can be set according to the designed range and point frequency requirements of the radar. The shorter the interval, the higher the point frequency. For a single channel, a 5 - microsecond sampling interval can obtain a 200K point frequency.

[0048] Step S108, based on each difference frequency signal corresponding to the first difference frequency signal and the second difference frequency signal, determine the object information in the detection space.

[0049] For example, based on the modulation bandwidths of the first difference frequency signal and the second difference frequency signal and the frequencies of the two signals, the distance between the lidar and the detection target object in the detection space can be determined.

[0050] When the modulation periods of the two lasers are both the target modulation period and the modulation bandwidths of the two lasers are both the target modulation bandwidth, the result obtained by dividing the product of the speed of light, the target modulation period, and the sum of the frequencies of the two signals by 8 times the target modulation bandwidth is determined as the distance between the lidar and the detection target object;

[0051] For example, in this embodiment, assume that the signal frequencies collected in a certain period are f11 and f21 respectively, the modulation periods of the two signals are the same and both are T, and the modulation bandwidths are divided into two cases, one is that the modulation bandwidths are the same, and the other is that the modulation bandwidths are different;

[0052] First, discuss the case where the modulation bandwidths are the same. Assume the modulation bandwidth is B. This case is the same as the full - period ranging, and the distance calculation is as shown in formula (1):

[0053]

[0054] where c is the speed of light, usually approximated as 3×10 8 m / s.

[0055] When the modulation periods of the two lasers are both the target modulation period and the modulation bandwidths of the two lasers are different, the result obtained by dividing the product of the speed of light, the target modulation period, and the sum of the two signal frequencies by 4 times the sum of the bandwidths of the two lasers' modulation bandwidths is determined as the distance between the lidar and the detected target object.

[0056] In this embodiment, the case where the modulation bandwidths are different is discussed. Let the bandwidth of signal 1 (f11) be B1 and the bandwidth of signal 2 (f21) be B2. The distance calculation formula is derived as follows:

[0057] Let the intermediate frequency signal frequency at distance d be fr. Then the distance intermediate frequencies of the two signals are as shown in formulas (2) and (3).

[0058]

[0059]

[0060] Considering the Doppler shift, the difference frequency signals of the two signals are as shown in formulas (4) and (5). Here, the Doppler shift refers to the phenomenon that when there is relative motion between the observer and the emission source, the frequency of the received signal changes due to the Doppler effect. This phenomenon can be observed in the propagation of various waves, including sound waves, electromagnetic waves, etc. In radar and wireless communication, the Doppler shift is an important effect. For example, when a radar system sends a signal to a moving target, the movement of the target will cause the frequency of the received signal to change, and this change is the Doppler shift. By analyzing the frequency change of the received signal, the motion state and speed of the target can be inferred.

[0061]

[0062]

[0063] Here, since the carrier frequencies of the two laser signals are the same or close, the Doppler effect difference is not significant, so the same value is taken.

[0064] From formulas (4) and (5), the distance calculation formula (6) can be obtained.

[0065]

[0066] The result obtained by dividing the product of the absolute value of the difference between the two signal frequencies and the optical carrier wavelength by 4 is determined as the moving speed of the detected target object relative to the lidar.

[0067] The Doppler frequency is given by Equation (7).

[0068]

[0069] The velocity is calculated as in Equation (8).

[0070] V = fd * λ / 2 Equation (8)

[0071] where λ is the optical carrier wavelength.

[0072] That is, the moving speed of the detected target object relative to the lidar is as in Equation (9).

[0073]

[0074] Through the above steps S102 to S108, a set of detection optical signals is provided and emitted into the detection space, where a set of detection optical signals includes two optical signals with different frequency change trend directions; the echo signals corresponding to the set of detection optical signals are received, and the echo signals are respectively heterodyned with the local oscillator optical signals of the two optical signals with different frequency change trend directions in the set of detection optical signals to determine the corresponding first heterodyne signal and second heterodyne signal; and, the first heterodyne signal is converted into a first electrical signal, and the second heterodyne signal is converted into a second electrical signal; synchronous data acquisition is performed on the first electrical signal and the second electrical signal to obtain a plurality of difference frequency signal pairs within the same modulation period, where a difference frequency signal pair includes a corresponding first difference frequency signal and second difference frequency signal; according to the first difference frequency signal and the second difference frequency signal corresponding to each difference frequency signal pair, the object information in the detection space is determined, solving the problem of low target detection efficiency of the lidar in the related art.

[0075] In an exemplary embodiment, providing a set of detection optical signals and emitting them into the detection space includes:

[0076] Splitting the first optical signal provided by the first laser and splitting the second optical signal provided by the second laser;

[0077] Combining one of the first optical signals and one of the second optical signals to obtain a first combined optical signal and emitting it into the detection space through the first scanning component; and, combining the other first optical signal and the other second optical signal to obtain a second combined optical signal and emitting it into the detection space through the second scanning component.

[0078] In this embodiment, in the multi-channel scheme, the detection optical signals of the two lasers are first split and then combined, and the same object is detected, and the return optical signals are heterodyned respectively.

[0079] Combination Figure 4 , Figure 4 shows a multi-channel scanning schematic diagram, including Channel 1, Channel 2, ……, Channel N. In a frequency-modulated continuous-wave lidar, the scanning scheme can be a mechanical rotating mirror scheme. Among them, in a system with two mirrors, the faster-rotating one is the fast mirror, and the slower-rotating one is the slow mirror, which respectively implement scanning in the horizontal and vertical directions, and require a relatively high reflectivity to reduce energy loss.

[0080] The scanning scheme can also be an OPA optical chip. If OPA is used for scanning, there is no lens; if OPA plus lens scanning is used, only one lens is required, that is, only one scanning component is required.

[0081] In an exemplary embodiment, before synchronously collecting data on the first electrical signal and the second electrical signal, the above method further includes:

[0082] Based on the detection range of the lidar, determine the maximum flight time of the detection signal emitted by the lidar within the detection range of the lidar;

[0083] Based on the maximum flight time, determine a preset sampling frequency, where the sampling frequency used for synchronously collecting data on the first electrical signal and the second electrical signal is the preset sampling frequency.

[0084] The echo signal is mixed with the local oscillator optical signal after a period of flight time. This period of flight time is the time from the emission of the transmitted signal separated from the laser signal to the return of the echo signal. The beat frequency signal generated by the echo signal and the local oscillator optical signal after the flight time is constant within a certain period of time and can accurately reflect the distance and speed information of the detection target. This period of time is the beat frequency time.

[0085] The principle of lidar ranging is to calculate the distance by measuring the time for light to be emitted from the laser, reflected by the detection target, and returned. According to the value of the speed of light c in a vacuum, the relationship between time and speed can be used to calculate the distance, Distance = Speed × Time / 2.

[0086] For example, if the lidar ranging range is 300m, the flight time of the ranging light is 2us.

[0087] Data acquisition can be performed on the electrical signal corresponding to the overlapping region of the beat frequency times of two optical signals with different frequency change trend directions. For example, the sampling time can be 1us, 2us, 3us, 4us, etc. Optionally, the preset sampling time can be less than or equal to the beat frequency time. Correspondingly, the preset sampling frequency can be expressed as the number of samples per second. The higher the sampling frequency, the shorter the sampling time interval.

[0088] Through this embodiment, by adjusting the sampling time to flexibly control the point frequency, it is possible to measure the distance and speed without collecting a complete cycle, thereby improving the target detection efficiency of the lidar.

[0089] The lidar detection method in this embodiment will be explained below with reference to optional examples.

[0090] By using two lasers with different wavelengths for inverse modulation, in this way, the modulation frequency can be reduced, such as to 10K, 1K, etc. Data can be collected in the overlapping region of the beat frequency time of the signal. The sampling time can be 1us, 2us, 3us, 4us, etc., and it can be selected according to the usage scenario. In this way, the point frequency can be flexibly controlled without being limited by the modulation speed.

[0091] Taking a single channel, 10Hz frame rate, 1K - 100G, and system accuracy of 7.5cm as an example: the maximum distance is 500m, the flight time is 3.3us, rounding up to 4us, then the effective time of the whole cycle is 996us; Table 1 shows the point frequencies that can be obtained with different sampling times.

[0092] Table 1

[0093] Sampling interval / μs Dot frequency / s Frame rate / Hz Single frame H*V / V*H 1 996K 10 100*996 2 498K 10 100*498 3 332K 10 100*332 4 249K 10 100*249 5 199.2K 10 100*199.2

[0094] The longer the sampling time, the more beneficial it is for the signal-to-noise ratio and calculation accuracy, the larger the measurable range, and correspondingly, the lower the point frequency.

[0095] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0096] Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium (such as ROM (Read-Only Memory), RAM (Random Access Memory), magnetic disk, optical disk), and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of the present application.

[0097] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing the relevant hardware of the terminal device through a program. The program can be stored in a computer-readable storage medium, and the storage medium can include: flash drive, ROM, RAM, magnetic disk, or optical disk, etc.

[0098] The serial numbers of the above embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0099] According to another aspect of the embodiments of the present application, a lidar is further provided. In combination with Figure 5 ,the lidar includes:

[0100] A light source 501 for providing a set of detection optical signals, where a set of detection optical signals includes two optical signals with different frequency change trend directions;

[0101] A scanning component 502 for respectively emitting a set of detection optical signals to the detection space;

[0102] A receiving module 503 for receiving echo signals corresponding to a set of detection optical signals, and respectively performing beat frequency with the local oscillator optical signals of two optical signals with different frequency change trend directions in a set of detection optical signals to determine a first beat frequency signal and a second beat frequency signal corresponding to a set of detection optical signals; and converting the first beat frequency signal into a first electrical signal and converting the second beat frequency signal into a second electrical signal;

[0103] A data acquisition module 504, electrically connected to the receiving module, for synchronously acquiring data of the first electrical signal and the second electrical signal to obtain multiple sets of corresponding first difference frequency signals and second difference frequency signals within the same modulation period;

[0104] The data processing module 505, electrically connected to the data acquisition module, is configured to determine object information in the detection space according to the corresponding first difference frequency signal and second difference frequency signal.

[0105] It should be noted that the light source 501 and the scanning component 502 in this embodiment can be used to execute the above-mentioned step S102, the receiving module 503 in this embodiment can be used to execute the above-mentioned step S104, the data acquisition module 504 in this embodiment can be used to execute the above-mentioned step S106, and the data processing module 505 in this embodiment can be used to execute the above-mentioned step S108.

[0106] Through the above modules, a set of detection optical signals is provided and emitted into the detection space, where a set of detection optical signals includes two optical signals with different frequency change trend directions; a set of echo signals corresponding to the detection optical signals is received, and the echo signals are respectively beat with the local oscillator optical signals of the two optical signals with different frequency change trend directions in the set of detection optical signals to determine the corresponding first beat frequency signal and second beat frequency signal; and, the first beat frequency signal is converted into a first electrical signal, and the second beat frequency signal is converted into a second electrical signal; synchronous data acquisition is performed on the first electrical signal and the second electrical signal to obtain a plurality of difference frequency signal pairs within the same modulation period, where a difference frequency signal pair includes a corresponding first difference frequency signal and second difference frequency signal; according to the first difference frequency signal and the second difference frequency signal corresponding to each difference frequency signal pair, the object information in the detection space is determined, which can solve the problem of low target detection efficiency of lidar in the related art.

[0107] In an exemplary embodiment, in combination with Figure 6 , the light source 501 includes a first laser and a second laser, where the first laser is configured to provide a first optical signal, the second laser is configured to provide a second optical signal, and the first optical signal and the second optical signal have different frequency change trend directions, constituting a set of detection optical signals.

[0108] In an exemplary embodiment, in combination with Figure 7 , the lidar further includes: a first beam splitter, a second beam splitter, a first combiner, and a second combiner, and the scanning component includes a first scanning component and a second scanning component, where

[0109] The first optical signal provided by the first laser is split by the first beam splitter and then provided to the first combiner and the second combiner respectively. The second optical signal provided by the second laser is split by the second beam splitter and then provided to the first combiner and the second combiner respectively. The first combiner combines the received first optical signal and second optical signal to obtain a first combined optical signal, which is provided to the first scanning component for emitting into the detection space. The second combiner combines the received first optical signal and second optical signal to obtain a second combined optical signal, which is provided to the second scanning component for emitting into the detection space.

[0110] If the integrated unit in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in the above computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in the storage medium and includes several instructions for causing one or more computer devices (which can be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in various embodiments of the present application.

[0111] In the above embodiments of the present application, the descriptions of the various embodiments each have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0112] In several embodiments provided by the present application, it should be understood that the disclosed client can be implemented in other ways. Among them, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there can be other division methods. 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 units or modules can be in electrical or other forms.

[0113] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or 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 provided in this embodiment.

[0114] In addition, in each embodiment of the present application, the various functional units can be integrated in one processing unit, or each unit can exist physically alone, or at least two units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0115] The above are only the preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A lidar detection method, characterized in that, Including: Providing a set of detection optical signals and emitting them into a detection space, where the set of detection optical signals includes two optical signals with different frequency change trend directions; Receiving echo signals corresponding to the set of detection optical signals, respectively performing beat frequency between the echo signals and local oscillator optical signals of the two optical signals with different frequency change trend directions in the set of detection optical signals to determine corresponding first beat frequency signals and second beat frequency signals; and converting the first beat frequency signal into a first electrical signal and converting the second beat frequency signal into a second electrical signal; Performing synchronous data acquisition on the first electrical signal and the second electrical signal to obtain multiple difference frequency signal pairs within the same modulation period, where each difference frequency signal pair includes a corresponding first difference frequency signal and a second difference frequency signal; Determining object information in the detection space according to the first difference frequency signal and the second difference frequency signal corresponding to each difference frequency signal pair.

2. The method according to claim 1, wherein The echo signals include a first echo signal and a second echo signal; The step of respectively performing beat frequency between the echo signals and local oscillator optical signals of the two optical signals with different frequency change trend directions in the set of detection optical signals to determine corresponding first beat frequency signals and second beat frequency signals includes: Performing beat frequency between the first echo signal and a corresponding first local oscillator optical signal through a first receiving module to obtain the first beat frequency signal, and performing beat frequency between the second echo signal and a corresponding second local oscillator optical signal through a second receiving module to obtain the second beat frequency signal.

3. The method according to claim 1, characterized in that, The lidar includes a first laser and a second laser, where the first laser is used to provide a first optical signal, the second laser is used to provide a second optical signal, and the first optical signal and the second optical signal have different frequency change trend directions and constitute the set of detection optical signals.

4. The method according to claim 3, wherein The step of providing a set of detection optical signals and emitting them into a detection space includes: Splitting the first optical signal provided by the first laser and splitting the second optical signal provided by the second laser; Emitting a first combined optical signal obtained by combining one beam of the first optical signal and one beam of the second optical signal into the detection space through a first scanning component; and emitting a second combined optical signal obtained by combining another beam of the first optical signal and another beam of the second optical signal into the detection space through a second scanning component.

5. The method according to claim 3, wherein Before providing a set of detection optical signals and emitting them into a detection space, the method further includes: Providing a first initial signal through the first laser and modulating the first initial signal into the first optical signal through a first modulation module; and Obtaining a second initial signal through the second laser and modulating the second initial signal into the second optical signal through a second modulation module.

6. The method according to any one of claims 1 to 5, characterized in that The two optical signals included in the set of detection optical signals have the same slope magnitude and opposite slope change trend directions; or, one of the two optical signals included in the set of detection optical signals is a fixed frequency signal and the other is a triangular wave signal.

7. The method according to any one of claims 1 to 5, characterized in that Before synchronously collecting data of the first electrical signal and the second electrical signal, the method further includes: Based on the detection range of the lidar, determining the maximum flight time of the detection signal emitted by the lidar within the detection range of the lidar; Determining a preset sampling frequency based on the maximum flight time, wherein the sampling frequency used for synchronously collecting data of the first electrical signal and the second electrical signal is the preset sampling frequency.

8. A lidar, characterized in that, Comprising: A light source for providing a set of detection optical signals, wherein the set of detection optical signals includes two optical signals with different frequency change trend directions; A scanning component for respectively emitting the set of detection optical signals into the detection space; A receiving module for receiving echo signals corresponding to the set of detection optical signals, and respectively performing beat frequency with the local oscillator optical signals of the two optical signals with different frequency change trend directions in the set of detection optical signals to determine a first beat frequency signal and a second beat frequency signal corresponding to the set of detection optical signals; and converting the first beat frequency signal into a first electrical signal and converting the second beat frequency signal into a second electrical signal; A data acquisition module electrically connected to the receiving module for synchronously collecting data of the first electrical signal and the second electrical signal to obtain multiple sets of corresponding first difference frequency signals and second difference frequency signals within the same modulation period; A data processing module electrically connected to the data acquisition module for determining object information in the detection space according to the corresponding first difference frequency signals and second difference frequency signals.

9. The lidar according to claim 8, characterized in that, The light source includes a first laser and a second laser, wherein the first laser is used to provide a first optical signal, the second laser is used to provide a second optical signal, and the first optical signal and the second optical signal have different frequency change trend directions, constituting the set of detection optical signals.

10. The lidar according to claim 9, wherein, The lidar further includes: a first beam splitter, a second beam splitter, a first combiner and a second combiner, and the scanning component includes a first scanning component and a second scanning component, wherein The first optical signal provided by the first laser is split by the first beam splitter and respectively provided to the first combiner and the second combiner, and the second optical signal provided by the second laser is split by the second beam splitter and respectively provided to the first combiner and the second combiner; the first combiner provides the first combined optical signal obtained by combining the received first optical signal and the second optical signal to the first scanning component to be emitted into the detection space, and the second combiner provides the second combined optical signal obtained by combining the received first optical signal and the second optical signal to the second scanning component to be emitted into the detection space.

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