Laser radar point cloud anti-crosstalk method and system based on random time delay

Abstract

The invention provides a laser radar point cloud anti-crosstalk method and system based on random time delay, and relates to the technical field of point cloud processing. Comprising the following steps: adding a random time delay amount on the basis of an original emission period of each emission channel of the laser radar, and obtaining a plurality of corresponding delay emission times when each emission channel emits laser in each period; each emission channel of the laser radar is controlled to emit laser according to the corresponding multiple delay emission times; acquiring an echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delay emission time; and filtering the obtained echo signal to obtain anti-crosstalk point cloud data. According to the method, random time delay is increased when a single channel emits laser, so that points, reaching adjacent receiving channels, of the emission channel are dispersed, anti-crosstalk of the laser radar point cloud is achieved, the recognition precision of the laser radar point cloud is improved, and the problem that noise points generated between different channels are recognized as real objects through a sensing algorithm, and misrecognition is caused is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radar point cloud processing, and in particular to a laser radar point cloud anti-crosstalk method and system based on random time delay. Background Art

[0002] LiDAR is widely used in autonomous driving vehicles. In parking scenarios, sensors such as LiDAR are usually used to perceive the parking scene point cloud data and plan the parking trajectory.

[0003] However, when the laser from the same source hits the same target, it will produce a false image, that is, noise, and the physical characteristics of the noise are very similar to the real image. Since the laser radar point cloud is a point cloud of the real three-dimensional world, and the noise is continuous in time and space, this will cause the perception algorithm to recognize the noise as a point cloud reflected from a real object, resulting in misidentification and then wrong planning.

[0004] At present, the laser radars used in mass-produced models are mostly mechanical or rotating mirror laser radars, and the transceiver devices are multi-channel combined transceivers. This will cause the lasers from the same light source to reach the laser receiving arrays of adjacent channels, forming three-dimensional point cloud features and an approximately uniform false image in the time dimension.

[0005] like Figure 1 As shown in the figure, for laser radar, it can be considered that the emitted lasers are emitted at the same time, that is, for a single channel, they are emitted periodically, such as once every 10 nanoseconds. At this time, the time when the laser from the same emitting light source is reflected to different channels is approximately the same. From D=V*t / 2, it can be known that the echo distances of different channels to the laser from the same emitting light source are the same, and at this time, false images will be generated between different channels. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a LiDAR point cloud anti-crosstalk method and system based on random time delay, which adds a random delay (nanosecond level) to the laser emission of a single channel, so that the discrete emission channel reaches the point of the adjacent receiving channel, thereby realizing the anti-crosstalk of the LiDAR point cloud, improving the recognition accuracy of the LiDAR point cloud, and solving the problem of misidentification caused by the perception algorithm identifying the noise points generated between different channels as real objects.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0008] The first aspect of the present invention provides a laser radar point cloud anti-crosstalk method based on random time delay.

[0009] The laser radar point cloud anti-crosstalk method based on random time delay includes the following steps:

[0010] A random time delay is added to the original transmission cycle of each transmission channel of the laser radar to obtain multiple delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle;

[0011] Control each transmitting channel of the laser radar to transmit laser according to the corresponding multiple delayed transmitting times;

[0012] Obtain the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time;

[0013] The acquired echo signal is filtered to obtain crosstalk-resistant point cloud data.

[0014] As an optional technical solution, the random delay is in nanoseconds.

[0015] As an optional technical solution, the multiple delayed emission times corresponding to each emission channel emitting lasers in each cycle are different.

[0016] As an optional technical solution, the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time is discretized.

[0017] As an optional technical solution, the discretization implementation process is:

[0018] Set the transmission channel X to transmit laser in the Mth transmission cycle according to the corresponding delayed transmission time M*t+dt, where t is the original transmission cycle and dt is the added random delay:

[0019] Then the echo distance value received by the receiving channel X according to the delayed emission time of M*t+dt is considered to be the same as the echo distance value of the laser emitted according to the original emission time of M*t, and the obtained point cloud is regularly and continuously distributed;

[0020] However, the echo distance value received by the adjacent channel of the receiving channel X according to the delayed emission time of M*t+dt has a distance difference of meters from the echo distance value of the laser emitted according to the original emission time of M*t. The obtained point cloud is irregularly distributed, realizing discretization.

[0021] As an optional technical solution, a voxel filtering method is used to filter the acquired echo signal to obtain crosstalk-resistant point cloud data.

[0022] As an optional technical solution, the voxel filtering method is used to filter the acquired echo signal, and the specific processing process is:

[0023] Set the kernel size in the voxel filtering method to n*n*n, and the distance between each kernel to xmm;

[0024] When the distance between y points in the point cloud of n*n*n area is greater than x, the point is considered to be a noise point;

[0025] Remove the detected noise.

[0026] A second aspect of the present invention provides a laser radar point cloud anti-crosstalk system based on random time delay.

[0027] The laser radar point cloud anti-crosstalk system based on random time delay includes:

[0028] The delay adding module is configured to: add a random delay amount based on the original transmission cycle of each transmission channel of the laser radar, so as to obtain a plurality of delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle;

[0029] The delayed emission module is configured to: control each emission channel of the laser radar to emit laser according to the corresponding multiple delayed emission times;

[0030] The discrete receiving module is configured to: obtain an echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time;

[0031] The filtering module is configured to: perform filtering processing on the acquired echo signal to obtain crosstalk-resistant point cloud data.

[0032] The third aspect of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps in the laser radar point cloud anti-crosstalk method based on random time delay as described in the first aspect of the present invention.

[0033] The fourth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the laser radar point cloud anti-crosstalk method based on random time delay as described in the first aspect of the present invention are implemented.

[0034] One or more of the above technical solutions have the following beneficial effects:

[0035] The present invention provides a laser radar point cloud anti-crosstalk method and system based on random time delay. First, a random time delay is added to the original transmission period of each transmission channel of the laser radar to obtain multiple delayed transmission times corresponding to the laser transmission of each transmission channel in each period. Then, each transmission channel of the laser radar is controlled to transmit laser according to the corresponding multiple delayed transmission times. In this way, discrete processing is realized for the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed transmission time. Finally, the discretized point cloud is filtered, which can easily remove noise points to obtain crosstalk-resistant point cloud data.

[0036] The method of the present invention is simple and easy to implement, improves the recognition accuracy of laser radar point cloud, realizes anti-crosstalk of laser radar point cloud, and solves the problem of misidentification caused by the perception algorithm identifying the noise points generated between different channels as real objects. It can be applied to vehicle parking systems to improve the operability and accuracy of parking.

[0037] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0039] Figure 1 Schematic diagram of the echo signal of the existing vehicle-mounted laser radar.

[0040] Figure 2 This is a flow chart of the method of the first embodiment.

[0041] Figure 3 This is a schematic diagram of channel time delay of the first embodiment.

[0042] Figure 4 This is a schematic diagram comparing the detection distances of the same point cloud in different channels in the time domain.

[0043] Figure 5 Schematic diagram of the comparison of detection distances of the same point cloud in different channels in space.

[0044] Figure 6 FIG. 4 is a schematic diagram of a voxel filtering method according to the first embodiment. DETAILED DESCRIPTION

[0045] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0046] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0047] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0048] Embodiment 1

[0049] As mentioned above, the laser radar of the prior art has the problem that the laser from the same light source reaches the laser receiving array of the adjacent channels to form three-dimensional point cloud features and an approximately unified false image in the time dimension. To address this problem, this embodiment discloses a laser radar point cloud anti-crosstalk method based on random time delay, which adds a random delay (nanosecond level) when a single channel emits laser, so that the discrete transmitting channel reaches the point of the adjacent receiving channel, realizes the distinction of the point cloud, and then realizes the anti-crosstalk of the laser radar point cloud, and improves the recognition accuracy of the laser radar point cloud.

[0050] This method can be applied in the field of intelligent recognition, for example, in the process of vehicle parking, and can effectively solve the problem of misidentification caused by the perception algorithm identifying the noise points generated between different channels as real objects.

[0051] like Figure 1 As shown, the laser radar point cloud anti-crosstalk method based on random time delay includes the following steps:

[0052] A random time delay is added to the original transmission cycle of each transmission channel of the laser radar to obtain multiple delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle;

[0053] Control each transmitting channel of the laser radar to transmit laser according to the corresponding multiple delayed transmitting times;

[0054] Obtain the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time;

[0055] The acquired echo signal is filtered to obtain crosstalk-resistant point cloud data.

[0056] In some embodiments, the random delay amount is in nanoseconds.

[0057] In some embodiments, the multiple delayed emission times corresponding to each emission channel emitting lasers in each cycle are different.

[0058] In some embodiments, the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time is discretized.

[0059] In some embodiments, the discretization is implemented as follows:

[0060] Set the transmission channel X to transmit laser in the Mth transmission cycle according to the corresponding delayed transmission time M*t+dt, where t is the original transmission cycle and dt is the added random delay:

[0061] Then the echo distance value received by the receiving channel X according to the delayed emission time of M*t+dt is considered to be the same as the echo distance value of the laser emitted according to the original emission time of M*t, and the obtained point cloud is regularly and continuously distributed;

[0062] However, the echo distance value received by the adjacent channel of the receiving channel X according to the delayed emission time of M*t+dt has a distance difference of meters from the echo distance value of the laser emitted according to the original emission time of M*t. The obtained point cloud is irregularly distributed, realizing discretization.

[0063] In the above technical solution, the random delay amount is set to the nanosecond level, and the multiple delayed emission times corresponding to each transmitting channel emitting lasers per cycle are different. This can well discretize the phantom point clouds of adjacent receiving channels, and use the random time delay method to encode the laser point cloud, thereby filtering out crosstalk noise.

[0064] In some embodiments, a voxel filtering method is used to filter the acquired echo signal to obtain crosstalk-resistant point cloud data.

[0065] In some embodiments, the voxel filtering method is used to filter the acquired echo signal, and the specific processing process is:

[0066] Set the kernel size in the voxel filtering method to n*n*n, and the distance between each kernel to xmm;

[0067] When the distance between y points in the point cloud of n*n*n area is greater than x, the point is considered to be a noise point;

[0068] Remove the detected noise.

[0069] Next, the technical solution of this embodiment will be explained in detail with reference to the accompanying drawings.

[0070] For laser radar, it can be considered that the emitted lasers are emitted at the same time. For a single channel, the emission is periodic, such as once every 10 nanoseconds. At this time, the time when the laser from the same emission light source is reflected to different channels is approximately the same. From D=V*t / 2, it can be known that false images will be generated between different channels.

[0071] exist Figure 1 In the laser radar, the transmitting module includes transmitting channel 1 and transmitting channel 2, and the receiving module includes receiving channel 1 and receiving channel 2. When the laser emitted by transmitting channel 1 and transmitting channel 2 passes through the scanning device and reaches the surface of the object, it is reflected and the emitted light is received and processed by receiving channel 1 and receiving channel 2.

[0072] In order to solve the above problems, for example, the present invention proposes to add a random delay (nanosecond level) to a single transmitting channel when emitting lasers to discretely determine the point where transmitting channel 1 reaches receiving channel 2, and then filter the clutter of receiving channel 2 through a filtering algorithm to reduce noise.

[0073] In this embodiment, the above solution is applied to the vehicle parking process as an example for explanation. It can be understood that before implementing this method, it is necessary to first determine the original emission cycle of each channel in the vehicle-mounted laser radar.

[0074] In addition, as is common knowledge in the art, a vehicle-mounted laser radar includes N channels, each of which includes a transmitting unit and a receiving unit; the laser emitted by the nth channel will be reflected to its adjacent channel at the same time. The laser radar laser emits a laser beam periodically.

[0075] Assuming that the laser emits laser once every 10ns, and the laser radar takes 100us to emit all the lasers in one cycle, the point cloud of the laser points of the nth channel of the multi-channel laser radar in the mth cycle is basically regularly distributed. Because in the 100us time, both the self-vehicle and the other vehicles are basically stationary. Of course, the laser of the nth channel will also be reflected to the n+1, n+2, ... channels at the same time. At this time, the point clouds similar to those of channel 1 will appear on these channels, which is the aforementioned illusion.

[0076] After obtaining the original transmission cycle of each transmission channel of the laser radar, a random delay is added to the original transmission cycle of each transmission channel of the laser radar to obtain multiple delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle. It can be understood that the delayed transmission time of each transmission channel transmitting lasers in each cycle is different. For details, please refer to Figure 3 As shown. Figure 3 In the example, the original transmission time is 0ns, 10ns, 20ns, etc., that is, the original transmission period is 10ns. In the second transmission period, a random delay of dt1=2ns is added to the original transmission time, so the second transmission time will be transmitted according to 10+2=12ns; in the third transmission period, a random delay of dt1=1ns is added to the original transmission time, so the second transmission time will be transmitted according to 10+1=11ns.

[0077] like Figure 3 As shown, by adding random delays such as 2ns, 3ns, 1ns, etc. to the transmitting point of a single channel, the echo signal from any channel to the adjacent channel can be discretized to discretize the pseudo image point cloud of the adjacent channel.

[0078] A random delay of several nanoseconds is added during the laser emission process of each channel. At this time, for channel one, the laser should be emitted periodically at time t, but due to the added delay dt, the laser of channel one will emit the laser at t+dt ns. However, during the dt ns process, the objects in the space can be considered to be stationary, so the echo distance value of the laser of channel one after the delay is the same as that without adding the delay.

[0079] But for channel 2, since the speed of light is 299792458m / s, the echo distance received by channel 2 will be reduced by 299792458x0.000000001dt. After conversion, there will be a meter-level distance difference with channel 1, and the delay time is different each time. At this time, the point cloud received by channel 2 from channel 1 will be irregularly distributed at the meter level.

[0080] In the time domain, it will appear similar Figure 4 The distance distribution shown in Figure 2 is as follows; in space, it will appear as Figure 5 It can be seen that the point cloud of channel one is regularly and continuously distributed, while the point cloud of channel two is irregularly distributed.

[0081] After acquiring the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time, the echo signal of the adjacent channel is filtered based on the voxel filtering method to obtain the anti-crosstalk point cloud data.

[0082] like Figure 6 As shown, in this embodiment, a 3x3x3 kernel is set, and the distance between each kernel is set to xmm. When there are y points in the point cloud of the 3x3x3 area whose distance is greater than x, the point is considered to be a noise point.

[0083] Since the distance between the points received by channel two and the points received by channel one after the delay is in the meter level, and the filter factor, that is, the distance between the kernels, is in the mm level, the point cloud caused by the crosstalk from channel one to channel two can be filtered out based on this characteristic.

[0084] The embodiment of the present invention increases a random delay (nanosecond level) to the laser emission of a single channel to discretely transmit the point where the transmitting channel reaches an adjacent receiving channel, and then filters the clutter of the adjacent channel through a filtering algorithm, thereby reducing noise points, thereby solving the problem of misidentification caused by the perception algorithm identifying the noise points generated between different channels as real objects.

[0085] As a specific application scenario, when this embodiment is applied to a vehicle parking system, it also specifically includes:

[0086] Step 1: Use the vehicle-mounted laser radar to collect anti-crosstalk point cloud data of the parking scene;

[0087] Step 2: Perform feature matching on the collected anti-crosstalk point cloud data, extract parking space information and road feature information from the point cloud data, and fit the parking trajectory;

[0088] Step 3: Use IMU sensor data to predict parking trajectory;

[0089] Step 4: Use the nonlinear least squares method to fuse the fitted parking trajectory and the predicted parking trajectory to obtain the optimal global pose.

[0090] Embodiment 2

[0091] This embodiment discloses a laser radar point cloud anti-crosstalk system based on random time delay.

[0092] The laser radar point cloud anti-crosstalk system based on random time delay includes:

[0093] The delay adding module is configured to: add a random delay amount based on the original transmission cycle of each transmission channel of the laser radar, so as to obtain a plurality of delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle;

[0094] The delayed emission module is configured to: control each emission channel of the laser radar to emit laser according to the corresponding multiple delayed emission times;

[0095] The discrete receiving module is configured to: obtain an echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time;

[0096] The filtering module is configured to: perform filtering processing on the acquired echo signal to obtain crosstalk-resistant point cloud data.

[0097] Embodiment 3

[0098] The purpose of this embodiment is to provide a computer-readable storage medium.

[0099] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the laser radar point cloud anti-crosstalk method based on random time delay as described in Example 1 of the present disclosure.

[0100] Embodiment 4

[0101] The purpose of this embodiment is to provide an electronic device.

[0102] An electronic device includes a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the steps in the laser radar point cloud anti-crosstalk method based on random time delay as described in Example 1 of the present disclosure are implemented.

[0103] The steps involved in the apparatuses of the above embodiments 2, 3 and 4 correspond to the method embodiment 1, and the specific implementation methods can refer to the relevant description part of embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood to include any medium that can store, encode or carry an instruction set for execution by a processor and enable the processor to execute any method in the present invention.

[0104] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0105] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A laser radar point cloud anti-crosstalk method based on random time delay, characterized in that: The following steps are involved: A random time delay is added to the original transmission cycle of each transmission channel of the laser radar to obtain multiple delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle; Control each transmitting channel of the laser radar to transmit laser according to the corresponding multiple delayed transmitting times; Obtain the echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time; The acquired echo signal is filtered to obtain crosstalk-resistant point cloud data.

2. The laser radar point cloud anti-crosstalk method based on random time delay as claimed in claim 1, characterized in that: The random delay is in nanosecond order.

3. The laser radar point cloud anti-crosstalk method based on random time delay as claimed in claim 1, characterized in that: The multiple delayed emission times corresponding to each emission channel emitting lasers in each cycle are different.

4. The laser radar point cloud anti-crosstalk method based on random time delay as claimed in claim 1, characterized in that: The echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time is discretized.

5. The laser radar point cloud anti-crosstalk method based on random time delay as claimed in claim 4, characterized in that: The implementation process of the discretization is: Set the transmission channel X to transmit laser in the Mth transmission cycle according to the corresponding delayed transmission time M*t+dt, where t is the original transmission cycle and dt is the added random delay: Then the echo distance value received by the receiving channel X according to the delayed emission time of M*t+dt is considered to be the same as the echo distance value of the laser emitted according to the original emission time of M*t, and the obtained point cloud is regularly and continuously distributed; However, the echo distance value received by the adjacent channel of the receiving channel X according to the delayed emission time of M*t+dt has a distance difference of meters from the echo distance value of the laser emitted according to the original emission time of M*t. The obtained point cloud is irregularly distributed, realizing discretization.

6. The laser radar point cloud anti-crosstalk method based on random time delay as claimed in claim 1, characterized in that: The acquired echo signal is filtered using the voxel filtering method to obtain crosstalk-resistant point cloud data.

7. The laser radar point cloud anti-crosstalk method based on random time delay as claimed in claim 6, characterized in that: The voxel filtering method is used to filter the acquired echo signal, and the specific processing process is as follows: Set the kernel size in the voxel filtering method to n*n*n, and the distance between each kernel to xmm; When the distance between y points in the point cloud of n*n*n area is greater than x, the point is considered to be a noise point; Remove the detected noise.

8. The laser radar point cloud anti-crosstalk system based on random time delay is characterized by: include: The delay adding module is configured to: add a random delay amount based on the original transmission cycle of each transmission channel of the laser radar, so as to obtain a plurality of delayed transmission times corresponding to each transmission channel transmitting lasers in each cycle; The delayed emission module is configured to: control each emission channel of the laser radar to emit laser according to the corresponding multiple delayed emission times; The discrete receiving module is configured to: obtain an echo signal received by each receiving channel of the laser radar when the laser is emitted according to the delayed emission time; The filtering module is configured to: perform filtering processing on the acquired echo signal to obtain crosstalk-resistant point cloud data.

9. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps in the laser radar point cloud anti-crosstalk method based on random time delay as described in any one of claims 1 to 7 are implemented.

10. An electronic device comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the laser radar point cloud anti-crosstalk method based on random time delay as described in any one of claims 1 to 7 are implemented.

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