Laser radar anti-interference method and device, laser radar and readable storage medium

Abstract

A laser radar anti-interference method and device, a laser radar and a readable storage medium, the method comprising: transmitting a target pulse sequence according to a preset transmission frequency of the laser radar and a random code value corresponding to each transmission pulse (S110); generating a target sequence, and using two adjacent transmission periods of the target sequence as a measurement period, the target sequence comprising a target pulse sequence and a target echo sequence returned by the target pulse sequence (S120); and according to the reception time of the two echo signals of the target measurement period, the random coding values corresponding to the two transmission pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar, filtering interference signals in the target measurement period (S120). According to the method, the emission frequency of the laser radar does not need to be increased, the anti-interference problem of the laser radar is effectively solved, the service life of the laser is prolonged, and the emission power consumption of the laser does not need to be increased under the condition that the measurement distance is not changed.

Description

Laser radar anti-interference method, device, laser radar and readable storage medium

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 31, 2023, with application number 202310384098.4, and invention name “Laser radar anti-interference method, device, laser radar and readable storage medium”, all contents of which are incorporated by reference into this application.

[0002] Technical Field

[0003] The present application relates to the field of radar, and in particular to a laser radar anti-interference method, device, laser radar and readable storage medium.

[0004] Background Art

[0005] With the development of autonomous driving technology, lidar has become an indispensable and important sensor, and higher requirements have been placed on its cost, performance, reliability, and anti-interference.

[0006] Existing technologies primarily achieve anti-interference through the use of dual or triple laser pulses. This involves emitting two or three laser pulses at a single measurement point, and adjusting the interval between the laser pulses to achieve pulse coding, thereby achieving the lidar's anti-interference function. However, for the same measurement point frequency, this solution requires doubling or tripling the laser's repetition rate, significantly impacting the laser's lifespan. Furthermore, to maintain the lidar's measurement distance, the laser's transmit power consumption must be increased.

[0007] Summary of the Invention

[0008] In order to solve the above technical problems, the embodiments of the present application provide a laser radar anti-interference method, device, laser radar and readable storage medium.

[0009] In a first aspect, an embodiment of the present application provides a laser radar anti-interference method, the method comprising:

[0010] According to the preset transmission frequency of the laser radar and the random code value corresponding to each transmission pulse, the target pulse sequence is transmitted;

[0011] generating a target sequence, and taking two adjacent transmission cycles of the target sequence as a measurement cycle, wherein the target sequence includes the target pulse sequence and a target echo sequence returned by the target pulse sequence;

[0012] According to the reception time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar and the preset error value of the laser radar, the interference signal within the target measurement period is filtered out.

[0013] In one embodiment, filtering out interference signals within the target measurement period according to the reception times of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar includes:

[0014] Calculating the reception time of two echo signals of the target measurement period;

[0015] Calculate a first judgment threshold and a second judgment threshold according to the random code values ​​corresponding to the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar;

[0016] Interference signals within the target measurement period are filtered out according to the reception times of the two echo signals of the target measurement period, the first judgment threshold, and the second judgment threshold.

[0017] In one embodiment, filtering out interference signals within the target measurement period according to the reception times of the two echo signals of the target measurement period, the first judgment threshold, and the second judgment threshold includes:

[0018] Determine whether the reception time of the two echo signals of the target measurement period, the first judgment threshold, and the second judgment threshold meet a preset judgment condition;

[0019] If so, determining that the reception time of the echo signal corresponding to the current transmitted pulse of the target measurement period is the time when the echo signal returns within the target measurement period;

[0020] If not, the interference signal within the target measurement period is filtered out according to a preset algorithm.

[0021] In one embodiment, the preset judgment condition is: the reception time interval between the reception moments of two echo signals in the target measurement period is greater than the first judgment threshold and less than the second judgment threshold.

[0022] In one embodiment, the method further includes: determining a current emission pulse of the target measurement period based on a preset emission period of the laser radar and a measurement distance of the target detected by the laser radar.

[0023] In one embodiment, determining the current emission pulse of the target measurement period according to the preset emission period of the laser radar and the measurement distance of the target detected by the laser radar includes:

[0024] Calculating the maximum measurement distance of the preset transmission period;

[0025] If the measurement distance is less than or equal to the maximum measurement distance, determining the first transmission pulse signal in the target measurement period as the current transmission pulse of the target measurement period;

[0026] If the measurement distance is greater than the maximum measurement distance, the second transmission pulse signal in the target measurement period is determined as the current transmission pulse of the target measurement period.

[0027] In one embodiment, if the measurement distance is less than or equal to the maximum measurement distance, the first judgment threshold and the second judgment threshold are calculated according to the random code values ​​corresponding to the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar, respectively, including:

[0028] Calculate the first judgment threshold according to the formula M1=Δt2-Δt1+T-t3;

[0029] Calculate the second judgment threshold according to the formula M2=Δt2-Δt1+T+t3;

[0030] Among them, M1 represents the first judgment threshold, M2 represents the second judgment threshold, Δt2 represents the random code value corresponding to the next transmission pulse of the current transmission pulse, Δt1 represents the random code value corresponding to the current transmission pulse, T represents the preset transmission period of the laser radar, and t3 represents the preset error value of the laser radar.

[0031] In one embodiment, if the measured distance is greater than the maximum measurement distance, the first judgment threshold and the second judgment threshold are calculated respectively according to the random code values ​​corresponding to the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar, including:

[0032] Calculate the first judgment threshold according to the formula M1=Δt4-Δt3+T-t3;

[0033] Calculate the second judgment threshold according to the formula M2=Δt4-Δt3+T+t3;

[0034] Among them, M1 represents the first judgment threshold, M2 represents the second judgment threshold, Δt4 represents the random code value corresponding to the current transmission pulse, Δt3 represents the random code value corresponding to the previous transmission pulse of the current transmission pulse, T represents the preset transmission period of the laser radar, and t3 represents the preset error value of the laser radar.

[0035] In one embodiment, the random code value ranges from -0.3 us to 0.3 us, and the preset error value ranges from 4 ns to 10 ns.

[0036] In one embodiment, transmitting a target pulse sequence according to a preset transmission frequency of the laser radar and a random code value corresponding to each transmission pulse includes:

[0037] Obtaining an initial emission time corresponding to each of the emission pulses according to a preset emission frequency of the laser radar;

[0038] Superimposing the corresponding random code value on the initial transmission time corresponding to each transmission pulse to obtain the actual transmission time of each transmission pulse;

[0039] The target pulse sequence is transmitted according to the actual transmission time of each transmission pulse.

[0040] In one embodiment, obtaining the initial emission time corresponding to each of the emission pulses according to the preset emission frequency of the laser radar includes:

[0041] generating an initial pulse sequence according to a preset transmission frequency of the laser radar;

[0042] An initial transmission time corresponding to each transmission pulse is obtained from the initial pulse sequence.

[0043] In one embodiment, generating a target sequence comprises:

[0044] receiving an echo signal returned by each of the transmitted pulses of the target pulse sequence after reaching the target detected by the laser radar;

[0045] Based on a time sequence, a target sequence is generated according to each transmit pulse of the target pulse sequence and the echo signal corresponding to each transmit pulse.

[0046] In a second aspect, an embodiment of the present application provides a laser radar anti-interference device, the device comprising:

[0047] The transmitting module is used to transmit the target pulse sequence according to the preset transmitting frequency of the laser radar and the random code value corresponding to each transmitting pulse;

[0048] a generating module, configured to generate a target sequence and use two adjacent transmission cycles of the target sequence as a measurement cycle, wherein the target sequence includes the target pulse sequence and a target echo sequence returned by the target pulse sequence;

[0049] The filtering module is used to filter out the interference signal within the target measurement period according to the reception time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar and the preset error value of the laser radar.

[0050] In a third aspect, an embodiment of the present application provides a laser radar, comprising a memory and a processor, wherein the memory is used to store a computer program, and when the computer program is run by the processor, the laser radar anti-interference method provided in the first aspect is executed.

[0051] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium storing a computer program, which, when running on a processor, executes the laser radar anti-interference method provided in the first aspect.

[0052] The laser radar anti-interference method provided in the above application adjusts the moment of each laser pulse emission under a relatively fixed repetition frequency, effectively solving the anti-interference problem of the laser radar, and does not require increasing the emission frequency of the laser, effectively improving the life of the laser and reducing the emission power consumption.

[0053] BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of this application and should not be regarded as limiting the scope of protection of this application. In each of the drawings, similar components are numbered similarly.

[0055] FIG1 shows a schematic flow chart of a laser radar anti-interference method according to an embodiment of the present application;

[0056] FIG2 shows a schematic diagram of an initial pulse sequence provided in an embodiment of the present application;

[0057] FIG3 is a schematic diagram showing a comparison between an initial pulse sequence and a target pulse sequence provided by an embodiment of the present application;

[0058] FIG4 is a schematic diagram showing a comparison of a target sequence corresponding to an initial pulse sequence and a target sequence corresponding to a target pulse sequence provided by an embodiment of the present application;

[0059] FIG5 is a schematic diagram showing another embodiment of the present application, wherein a target sequence corresponding to an initial pulse sequence and a target sequence corresponding to a target pulse sequence are compared;

[0060] FIG6 shows a schematic structural diagram of a laser radar anti-interference device provided in an embodiment of the present application;

[0061] FIG7 shows a schematic structural diagram of a laser radar provided in an embodiment of the present application.

[0062] DETAILED DESCRIPTION

[0063] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0064] The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but rather merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0065] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present application, are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0066] Furthermore, the terms “first,” “second,” “third,” etc., are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0067] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meaning as in the context of the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present application.

[0068] Example 1

[0069] The embodiment of the present application provides a laser radar anti-interference method. Specifically, referring to FIG1 , the laser radar anti-interference method includes:

[0070] Step S110, transmitting a target pulse sequence according to a preset transmission frequency of the laser radar and a random code value corresponding to each transmission pulse;

[0071] In a typical LiDAR system, the LiDAR's transmitter module emits laser pulses at a fixed frequency. See Figure 2, which shows a standard 500KHZ transmitter system. That is, the time interval between each laser pulse is 2µs. The measured distance within a single measurement cycle is:

[0072] (2us*c) / 2≈300m Formula 1

[0073] Here, c represents the speed of light. A single measurement cycle consists of one round trip, so the value needs to be divided by 2. Therefore, the radar system shown in Figure 2 has a maximum measurement range of 300 meters. Beyond 300 meters, it will be impossible to distinguish between signals returning from the current measurement cycle and signals from other measurement cycles (previous measurement cycles). This means that standard fixed-frequency radar systems have poor anti-interference capabilities and cannot distinguish between valid signals and interfering signals.

[0074] Based on this, the present embodiment improves upon a fixed-frequency radar system by incorporating random coding values ​​to adjust the timing of each transmitted pulse. See Figure 3, which illustrates a comparison between an initial pulse sequence and a target pulse sequence, according to an embodiment of the present invention. For example, using a 500kHz transmission system as an example, while maintaining the total number of transmission points, each transmission timing is adjusted left or right, with the adjustment amplitude (i.e., the random coding value) controlled within a preset adjustment range.

[0075] Preferably, the random code value ranges from -0.3µs to 0.3µs. This ensures a flexible adjustment range without affecting the measurement range. Exceeding this range risks affecting the measurement range. Within the adjustment range, the adjustment amplitude can be randomly varied. In other words, each transmitted pulse is randomly encoded based on the random code value to transmit the target pulse sequence.

[0076] In an embodiment of the present application, based on the preset transmission frequency of the laser radar and the random coding value corresponding to each transmission pulse, transmitting a target pulse sequence includes: obtaining the initial transmission time corresponding to each transmission pulse based on the preset transmission frequency of the laser radar; superimposing the corresponding random coding value on the initial transmission time corresponding to each transmission pulse to obtain the actual transmission time of each transmission pulse; and transmitting the target pulse sequence according to the actual transmission time of each transmission pulse.

[0077] Furthermore, according to the preset transmission frequency of the laser radar, obtaining the initial transmission moment corresponding to each transmission pulse includes: generating an initial pulse sequence according to the preset transmission frequency of the laser radar; and obtaining the initial transmission moment corresponding to each transmission pulse from the initial pulse sequence.

[0078] Step S120 , generating a target sequence, and taking two adjacent transmission cycles of the target sequence as a measurement cycle, wherein the target sequence includes the target pulse sequence and the target echo sequence returned by the target pulse sequence; wherein the target pulse sequence represents the transmission sequence, and the target echo sequence represents the returned sequence.

[0079] In an embodiment of the present application, generating a target sequence includes: receiving an echo signal returned after each transmitted pulse of the target pulse sequence reaches the target detected by the laser radar; based on the time sequence, generating the target sequence according to each transmitted pulse of the target pulse sequence and the echo signal corresponding to each transmitted pulse.

[0080] Please refer to Figure 4, which shows a schematic diagram of comparing a target sequence corresponding to an initial pulse sequence and a target sequence corresponding to a target pulse sequence provided in an embodiment of the present application; Figure 4 adds the echo signal after laser emission on the basis of Figure 3, assuming that the echo signal in the figure is approximately 0.2us after emission, that is, the target of the return signal is approximately at 0.2us*c / 2=30m. When a fixed emission frequency is used, the position of the echo is relatively fixed, but when the emission moment is randomly adjusted, the position of the echo signal will also change randomly. Therefore, the present application uses two adjacent emission cycles as a measurement cycle to calculate the position of the echo signal. For example, the first and second emission cycles are combined into measurement cycle T1, the second and third emission cycles are combined into measurement cycle T2, and so on.

[0081] Step S130, filtering out the interference signal within the target measurement period according to the reception time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar and the preset error value of the laser radar.

[0082] The target measurement period here is the measurement period currently to be measured in step S120. In one embodiment, filtering out interference signals within the target measurement period based on the reception time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar includes:

[0083] Calculate the receiving time of the two echo signals of the target measurement period; calculate the first judgment threshold and the second judgment threshold respectively according to the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar and the preset error value of the laser radar; filter out the interference signal within the target measurement period according to the receiving time of the two echo signals of the target measurement period, the first judgment threshold and the second judgment threshold.

[0084] Preferably, the preset error value ranges from 4ns to 10ns. This is due to the consideration of the errors that exist in the LiDAR system. There are many reasons for the error, such as air refraction error, scanning angle error, etc. Considering the various errors that may occur, a generally reasonable preset error value range is 4ns to 10ns.

[0085] In one embodiment, filtering out interference signals within the target measurement period according to the reception times of the two echo signals of the target measurement period, the first judgment threshold, and the second judgment threshold includes:

[0086] Determine whether the reception time of the two echo signals of the target measurement period, the first judgment threshold, and the second judgment threshold meet a preset judgment condition;

[0087] If so, determine that the reception time of the echo signal corresponding to the current transmission pulse of the target measurement period is the time when the echo signal returns within the target measurement period; if not, filter out the interference signal within the target measurement period according to a preset algorithm.

[0088] Specifically, two judgment thresholds may be calculated using some influencing parameters of the target measurement period, so as to calculate the normal signal and the interference signal according to the judgment thresholds.

[0089] Specifically, in one embodiment, the preset judgment condition is: the reception time interval between the reception moments of two echo signals in the target measurement period is greater than the first judgment threshold and less than the second judgment threshold.

[0090] In one embodiment, the method further includes: determining a current emission pulse of the target measurement period based on a preset emission period of the laser radar and a measurement distance of the target detected by the laser radar.

[0091] In one embodiment, determining the current emission pulse of the target measurement period according to the preset emission period of the laser radar and the measurement distance of the target detected by the laser radar includes:

[0092] Calculate the maximum measurement distance of the preset transmission cycle; if the measurement distance is less than or equal to the maximum measurement distance, determine the first transmission pulse signal within the target measurement cycle as the current transmission pulse of the target measurement cycle; if the measurement distance is greater than the maximum measurement distance, determine the second transmission pulse signal within the target measurement cycle as the current transmission pulse of the target measurement cycle.

[0093] The maximum measurement distance is determined by the preset transmission frequency of the lidar, specifically, the preset transmission frequency multiplied by the speed of light divided by 2. This step is to achieve cross-cycle measurement to avoid receiving echoes from the previous transmission cycle during the current transmission cycle.

[0094] In one embodiment, if the measurement distance is less than or equal to the maximum measurement distance, the first judgment threshold and the second judgment threshold are calculated according to the random code values ​​corresponding to the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar, respectively, including:

[0095] Calculate the first judgment threshold according to the formula M1=Δt2-Δt1+T-t3;

[0096] Calculate the second judgment threshold according to the formula M2=Δt2-Δt1+T+t3;

[0097] Among them, M1 represents the first judgment threshold, M2 represents the second judgment threshold, Δt2 represents the random code value corresponding to the next transmission pulse of the current transmission pulse, Δt1 represents the random code value corresponding to the current transmission pulse, T represents the preset transmission period of the laser radar, and t3 represents the preset error value of the laser radar.

[0098] Specifically, as shown in Figure 4, when the target to be measured is within the maximum measurement distance, the first transmitted pulse signal within the target measurement period T1 is determined as the current transmitted pulse of the target measurement period T1. Assuming that in the measurement period T1, the receiving time of the first echo signal is t1, and the receiving time of the second echo signal is t2, the receiving time of the echo signal corresponding to the current transmitted pulse signal is t1. Since the time interval between the two transmitted pulse signals within the target measurement period T1 and the time interval between the echo signals corresponding to the two transmitted pulse signals will not change suddenly, t2-t1≈Δt, where Δt is the time interval between the two transmitted pulse signals.

[0099] At the same time, assuming that the transmission time of the current transmission pulse signal differs from the standard preset transmission frequency by Δt1 (i.e., the random code value Δt1 corresponding to the current transmission pulse signal), Δt1=0, and the transmission time of the next transmission pulse signal differs from the preset transmission frequency by Δt2 (i.e., the random code value Δt2 corresponding to the next transmission pulse signal), Δt2=-0.2 us, then the time interval between the two transmission pulse signals within the target measurement period T1 can be calculated as Δt=Δt2-Δt1+T, where T represents the preset transmission period under the standard transmission frequency. The preset transmission period T, the random code value Δt1 corresponding to the current transmission pulse signal, and the random code value Δt2 corresponding to the next transmission pulse signal are known. As shown in Figure 4, within the target measurement period T1, the time interval between the two transmission pulse signals is Δt=Δt2-Δt1+T=-0.2-0+2=1.8 us.

[0100] In addition, when making a judgment, because the laser radar system itself may have errors, a preset error value t3 needs to be reserved. The preset error value t3 can be determined based on the error value of the laser radar system.

[0101] Specifically, the first judgment threshold M1 can be calculated according to the following formula:

[0102] M1=Δt2-Δt1+T-t3 Formula 2

[0103] The second judgment threshold M2 is calculated according to the following formula 3:

[0104] M2=Δt2-Δt1+T+t3 Formula 3

[0105] If the time interval between the reception times of the first echo signal t1 and the second echo signal t2 during the target measurement period T1 is greater than the first judgment threshold M1 and less than the second judgment threshold M2, that is, if the condition Δt2-Δt1+T-t3<t2-t1<Δt2-Δt1+T+t3 is satisfied during the target measurement period T1, then the reception time of the first echo signal is determined to be t1, the time at which the echo signal returns within the target measurement period T1. This means that the reception time of the echo signal corresponding to the current transmitted pulse during the target measurement period is determined to be the time at which the echo signal returns within the target measurement period. This condition is not met in the presence of other interfering signals, and the interfering signals can be effectively filtered out using a preset algorithm. Because Δt1 and Δt2 vary randomly, identification can be achieved through random code values. Compared to traditional double-pulse laser transmission, this method does not require increasing the laser's transmission frequency, thus reducing the laser's lifespan and increasing transmission power consumption.

[0106] The lidar anti-interference method provided in the above embodiment effectively identifies interference signals and filters them out according to a preset algorithm by adjusting the timing of each laser pulse emission, while maintaining a relatively fixed repetition rate. Furthermore, compared to existing methods such as double-emission laser pulses, this method eliminates the need to increase the laser's emission frequency, effectively reducing emission power consumption and extending the laser's lifespan.

[0107] In one embodiment, if the measured distance is greater than the maximum measurement distance, the first judgment threshold and the second judgment threshold are calculated respectively according to the random code values ​​corresponding to the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar, including:

[0108] Calculate the first judgment threshold according to the formula M1=Δt4-Δt3+T-t3;

[0109] Calculate the second judgment threshold according to the formula M2=Δt4-Δt3+T+t3;

[0110] Among them, M1 represents the first judgment threshold, M2 represents the second judgment threshold, Δt4 represents the random code value corresponding to the current transmission pulse, Δt3 represents the random code value corresponding to the previous transmission pulse of the current transmission pulse, T represents the preset transmission period of the laser radar, and t3 represents the preset error value of the laser radar.

[0111] In addition, the embodiment of the present application can also realize cross-cycle measurement, as shown in Figure 5, which shows a schematic diagram of comparing the target sequence corresponding to another initial pulse sequence and the target sequence corresponding to the target pulse sequence provided by the embodiment of the present application. When the measurement distance of the measured target is far, exceeding the maximum measurement distance, assuming that the echo signal returned by the measured target is 2.4us away from the emission moment, at this time, the measurement distance of the measured target is equal to 2.4*c / 2=360m, where c is the speed of light. If a fixed 500KHZ repetition frequency is used, a measurement error will occur in the next measurement cycle, and it will be misjudged as an object at 2.4-2=0.4us, that is, 60m.

[0112] Therefore, when the target pulse sequence is transmitted using the method for randomly adjusting the transmission time provided in this embodiment, taking the target measurement period T2 as an example, the second transmission pulse signal within the target measurement period T2 is determined as the current transmission pulse of the target measurement period T2. Assuming that the reception time of the first echo signal is calculated to be t3 and the reception time of the second echo signal is t4, the reception time of the echo signal corresponding to the current transmission pulse signal is t4. At the same time, assuming that the transmission time of the current transmission pulse signal differs from the standard preset transmission frequency by Δt4 (that is, the random code value Δt4 corresponding to the current transmission pulse signal), Δt4=0.1 us, and the transmission time of the previous transmission pulse signal differs from the standard preset transmission frequency by Δt3 (that is, the random code value Δt3 corresponding to the previous transmission pulse signal), Δt3=-0.2 us. Since the time interval between the two transmitted pulse signals and the time interval of the echo signals corresponding to the two transmitted pulse signals do not change suddenly within the target measurement period T2, we can obtain t4-t3≈Δt4-Δt3+T, where T represents the preset transmission period at the standard transmission frequency. The preset transmission period T, the random code value Δt4 corresponding to the current transmitted pulse signal, and the random code value Δt3 corresponding to the previous transmitted pulse signal are known. Therefore, t4-t3≈0.1-(-0.2)+2=2.3 us.

[0113] In addition, when making a judgment, because the laser radar system itself may have errors, a preset error value t3 needs to be reserved. The preset error value t3 can be determined based on the error value of the laser radar system.

[0114] Specifically, the new first judgment threshold M1 can be calculated according to the following formula:

[0115] M1=Δt4-Δt3+T-t3 Formula 4

[0116] The new second judgment threshold M2 is calculated according to the following formula:

[0117] M2=Δt4-Δt3+T+t3 Formula 5

[0118] If the time interval between the reception times of the first echo signal t3 and the second echo signal t4 in target measurement period T2 is greater than the first judgment threshold M1 and less than the second judgment threshold M2, that is, if the condition Δt4-Δt3+T-t3<t4-t3<Δt4-Δt3+T+t3 is satisfied during target measurement period T2, then the reception time of the second echo signal is determined to be t4, the time at which the echo signal returns within target measurement period T2. In other words, the reception time of the echo signal corresponding to the current transmitted pulse in the target measurement period is determined to be the time at which the echo signal returns within the target measurement period. This condition is not met in the presence of other interfering signals, and the interfering signals can be effectively filtered out using the preset algorithm. Because Δt4 and Δt3 vary randomly, identification through random code values ​​can be achieved.

[0119] This embodiment enables cross-cycle measurement. When the target is far away, the echo signal's return time is determined to be greater than a first threshold value M1 and less than a second threshold value M2. This allows the echo signal to be received within the target's measurement period. This avoids measurement errors caused by the target's distance exceeding the maximum measurement range of the lidar, significantly improving the lidar's range and addressing interference issues.

[0120] In summary, the lidar anti-interference method provided in this embodiment effectively solves the lidar's anti-interference problem by adjusting the timing of each laser pulse transmission while maintaining a relatively fixed repetition rate. It also implements cross-cycle transmission coding, enabling cross-cycle measurement and significantly improving the lidar's ranging range. This embodiment eliminates the need to increase the laser's transmission frequency, effectively extending the laser's lifespan and reducing transmission power consumption.

[0121] Example 2

[0122] This embodiment further provides a laser radar anti-interference device. Referring to FIG6 , the laser radar anti-interference device 600 includes:

[0123] The transmitting module 610 is used to transmit a target pulse sequence according to a preset transmitting frequency of the laser radar and a random code value corresponding to each transmitting pulse;

[0124] A generating module 620 is configured to generate a target sequence and use two adjacent transmission cycles of the target sequence as a measurement cycle, wherein the target sequence includes the target pulse sequence and a target echo sequence returned by the target pulse sequence;

[0125] The filtering module 630 is used to filter out the interference signal within the target measurement period according to the reception time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar and the preset error value of the laser radar.

[0126] The laser radar anti-interference device provided in this embodiment can implement the laser radar anti-interference method provided in Example 1. To avoid repetition, it will not be repeated here.

[0127] The lidar anti-interference device provided in this embodiment adjusts the timing of each laser pulse emission while maintaining a relatively fixed repetition rate, effectively addressing the lidar's anti-interference issues. It also implements cross-cycle transmission coding, enabling cross-cycle measurement and significantly increasing the lidar's ranging range. This embodiment eliminates the need to increase the laser's transmission frequency, effectively extending the laser's lifespan and reducing transmission power consumption.

[0128] Example 3

[0129] This embodiment also provides a laser radar 700, see Figure 7. The laser radar 700 shown in Figure 7 includes a transmitter 710, a receiver 720, a memory 730 and a processor 740. The memory stores a computer program, and the computer program executes the laser radar anti-interference method described in Example 1 when the processor is running.

[0130] The lidar provided in this embodiment adjusts the timing of each laser pulse emission while maintaining a relatively fixed repetition rate, effectively addressing the lidar's anti-interference capabilities. It also implements cross-cycle transmission encoding, enabling cross-cycle measurement and significantly increasing the lidar's ranging range. This embodiment eliminates the need to increase the laser's transmission frequency, effectively extending the laser's lifespan and reducing transmission power consumption.

[0131] Example 4

[0132] This embodiment further provides a computer-readable storage medium storing a computer program. When the computer program is run on a processor, the laser radar anti-interference method as described in Example 1 is executed.

[0133] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or terminal comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or terminal comprising the element.

[0134] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0135] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose and protection scope of this application, all of which are protected by this application.

Claims

1. A laser radar anti-interference method, characterized in that: The method comprises: According to the preset transmission frequency of the laser radar and the random code value corresponding to each transmission pulse, a target pulse sequence is transmitted; generating a target sequence, and taking two adjacent transmission cycles of the target sequence as a measurement cycle, wherein the target sequence includes the target pulse sequence and a target echo sequence returned by the target pulse sequence; According to the receiving time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitting pulse signals of the target measurement period, the preset transmitting period of the laser radar and the preset error value of the laser radar, the interference signal within the target measurement period is filtered out.

2. The method according to claim 1, characterized in that The method of filtering out interference signals within the target measurement period according to the receiving time of two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar, and the preset error value of the laser radar includes: Calculating the reception time of two echo signals of the target measurement period; Calculate a first judgment threshold and a second judgment threshold respectively according to the random code values ​​corresponding to the two emission pulse signals of the target measurement period, the preset emission period of the laser radar, and the preset error value of the laser radar; Interference signals in the target measurement period are filtered out according to the receiving times of the two echo signals in the target measurement period, the first judgment threshold, and the second judgment threshold.

3. The method according to claim 2, characterized in that The filtering out interference signals within the target measurement period according to the reception time of the two echo signals of the target measurement period, the first judgment threshold and the second judgment threshold includes: Determine whether the reception time of the two echo signals of the target measurement period, the first judgment threshold and the second judgment threshold meet a preset judgment condition; If so, determining that the reception time of the echo signal corresponding to the current transmission pulse of the target measurement period is the time when the echo signal returns within the target measurement period; If not, the interference signal within the target measurement period is filtered out according to a preset algorithm.

4. The method according to claim 3, characterized in that The preset judgment condition is: the receiving time interval between the receiving moments of two echo signals in the target measurement period is greater than the first judgment threshold and less than the second judgment threshold.

5. The method according to claim 3, characterized in that The method further includes: determining a current emission pulse of the target measurement period according to a preset emission period of the laser radar and a measurement distance of a target detected by the laser radar.

6. The method according to claim 5, characterized in that The step of determining the current emission pulse of the target measurement period according to the preset emission period of the laser radar and the measurement distance of the target detected by the laser radar comprises: Calculating the maximum measurement distance of the preset transmission period; If the measurement distance is less than or equal to the maximum measurement distance, determining the first transmission pulse signal in the target measurement period as the current transmission pulse of the target measurement period; If the measurement distance is greater than the maximum measurement distance, the second transmission pulse signal in the target measurement period is determined as the current transmission pulse of the target measurement period.

7. The method according to claim 6, characterized in that If the measurement distance is less than or equal to the maximum measurement distance, the first judgment threshold and the second judgment threshold are calculated respectively according to the random code values ​​corresponding to the two emission pulse signals of the target measurement period, the preset emission period of the laser radar, and the preset error value of the laser radar, including: According to the formula M1=Δt2-Δt1+T-t3, the first judgment threshold is calculated; According to the formula M2=Δt2-Δt1+T+t3, the second judgment threshold is calculated; Among them, M1 represents the first judgment threshold, M2 represents the second judgment threshold, Δt2 represents the random code value corresponding to the next transmission pulse of the current transmission pulse, Δt1 represents the random code value corresponding to the current transmission pulse, T represents the preset transmission period of the laser radar, and t3 represents the preset error value of the laser radar.

8. The method according to claim 6, characterized in that If the measurement distance is greater than the maximum measurement distance, the first judgment threshold and the second judgment threshold are calculated respectively according to the random code values ​​corresponding to the two emission pulse signals of the target measurement period, the preset emission period of the laser radar, and the preset error value of the laser radar, including: According to the formula M1=Δt4-Δt3+T-t3, the first judgment threshold is calculated; According to the formula M2=Δt4-Δt3+T+t3, the second judgment threshold is calculated; Among them, M1 represents the first judgment threshold, M2 represents the second judgment threshold, Δt4 represents the random code value corresponding to the current transmission pulse, Δt3 represents the random code value corresponding to the previous transmission pulse of the current transmission pulse, T represents the preset transmission period of the laser radar, and t3 represents the preset error value of the laser radar.

9. The method according to claim 1, characterized in that The random code value ranges from -0.3us to 0.3us, and the preset error value ranges from 4ns to 10ns.

10. The method according to any one of claims 1 to 9, characterized in that The method of transmitting a target pulse sequence according to a preset transmission frequency of the laser radar and a random code value corresponding to each transmission pulse includes: According to the preset transmission frequency of the laser radar, obtaining the initial transmission time corresponding to each of the transmission pulses; Superimposing the corresponding random code value on the initial emission time corresponding to each of the emission pulses to obtain the actual emission time of each of the emission pulses; The target pulse sequence is transmitted according to the actual transmission time of each of the transmission pulses.

11. The method according to claim 10, characterized in that The step of obtaining the initial emission time corresponding to each emission pulse according to the preset emission frequency of the laser radar includes: Generate an initial pulse sequence according to a preset transmission frequency of the laser radar; An initial emission time corresponding to each emission pulse is obtained from the initial pulse sequence.

12. The method according to claim 11, characterized in that The generating of the target sequence comprises: Receiving an echo signal returned after each of the transmitted pulses of the target pulse sequence reaches the target detected by the laser radar; Based on the time sequence, a target sequence is generated according to each transmit pulse of the target pulse sequence and the echo signal corresponding to each transmit pulse.

13. A laser radar anti-interference device, characterized in that: The device comprises: A transmitting module, used to transmit a target pulse sequence according to a preset transmitting frequency of the laser radar and a random code value corresponding to each transmitting pulse; A generating module, used for generating a target sequence and taking two adjacent transmission cycles of the target sequence as a measurement cycle, wherein the target sequence includes the target pulse sequence and a target echo sequence returned by the target pulse sequence; The filtering module is used to filter out the interference signal within the target measurement period according to the reception time of the two echo signals of the target measurement period, the corresponding random code values ​​of the two transmitted pulse signals of the target measurement period, the preset transmission period of the laser radar and the preset error value of the laser radar.

14. A laser radar, characterized in that: It comprises a transmitter, a receiver, a memory and a processor, wherein the memory stores a computer program, and when the computer program is run by the processor, the laser radar anti-interference method described in any one of claims 1 to 12 is executed.

15. A computer-readable storage medium, characterized in that: It stores a computer program, which, when running on a processor, executes the laser radar anti-interference method described in any one of claims 1 to 12.

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