CN118112542A

CN118112542A - Laser radar walking error compensation method and device, radar equipment and storage medium

Info

Publication number: CN118112542A
Application number: CN202410263847.2A
Authority: CN
Inventors: 刘智; 石俊锋; 黄文锋
Original assignee: Guangzhou Asensing Technology Co Ltd
Current assignee: Guangzhou Asensing Technology Co Ltd
Priority date: 2024-03-07
Filing date: 2024-03-07
Publication date: 2024-05-31

Abstract

The invention relates to the field of laser radars, and discloses a laser radar walking error compensation method, a laser radar walking error compensation device, radar equipment and a storage medium, wherein the method comprises the following steps: acquiring a laser signal reflected by a laser radar from a target object; processing the laser signal according to a set voltage threshold value to obtain corresponding signal processing data; according to the signal processing data, calculating to obtain an error compensation value of the flight time of the laser signal; and compensating the flight time according to the error compensation value to obtain compensated flight time. The accuracy of distance measurement is improved, and walking errors caused by signal amplitude are improved.

Description

Laser radar walking error compensation method and device, radar equipment and storage medium

Technical Field

The present invention relates to the field of lidar, and in particular, to a method and apparatus for compensating a walking error of a lidar, a radar device, and a storage medium.

Background

The laser radar distance calibration refers to accurately calibrating the laser radar distance output, so that the radar can accurately measure the distance between a target object and the radar. The current laser radar ranging technology mainly measures the distance between a target object and a radar according to the Time-of-flight (Time-of-flight) of laser light by emitting a laser beam and receiving the reflected laser beam. The received signal deviates from the actual range, so the lidar needs to determine the deviation of the range output, typically by measuring a reference object of known distance, such as a reflecting plate. The range error of the received signal of the lidar device due to the difference in signal amplitude is referred to as a walk error. Most of the prior art is to perform peak searching according to the waveform of the received signal, but in order to save cost, many devices only detect the signal in a time-sharing manner, so that the peak searching is difficult. And if the laser radar adopting the time-sharing scheme only uses the front edge to calculate the distance, the walking error is difficult to repair.

Disclosure of Invention

In a first aspect, the present application provides a laser radar walking error compensation method, including:

acquiring a laser signal reflected by a laser radar from a target object;

Processing the laser signal according to a set voltage threshold value to obtain corresponding signal processing data;

and calculating an error compensation value of the flight time of the laser signal according to the signal processing data.

And compensating the flight time according to the error compensation value to obtain compensated flight time.

Further, the two set voltage thresholds are used, and the processing the laser signal according to the set voltage thresholds to obtain corresponding signal processing data includes:

Generating a first time-sharing signal and a second time-sharing signal of the laser signal according to the set two voltage thresholds;

And acquiring a first rising edge moment of the first time-sharing signal and a second rising edge moment of the second time-sharing signal.

Further, the processing the signal processing data to obtain an error compensation value of the time of flight of the laser signal includes:

Acquiring a preset walking error compensation model;

and taking the time difference between the first rising edge time and the second rising edge time as an independent variable to be taken into the walking error compensation model to obtain an error compensation value.

Further, the acquiring the first rising edge time of the first time-division signal and the second rising edge time of the second time-division signal includes:

acquiring a Gaussian wave average value of the laser signal;

and calculating the first rising edge moment and the second rising edge moment according to the Gaussian average value and the set two voltage thresholds.

Further, the expression of the walking error compensation model is:

F(x)＝Ae^Bx+C；

wherein x is the independent variable, A, B, C is the fitting coefficient of the walking error compensation model, and e is the natural logarithm.

Calculating the time difference between the first rising edge moment and the second rising edge moment, calculating the voltage difference between the two set voltage thresholds, and taking the quotient of the time difference and the voltage difference as an independent variable into a preset walking error compensation model to obtain an error compensation value.

Further, the processing the laser signal according to the set voltage threshold to obtain corresponding signal processing data, further includes:

If the laser signal is not a standard Gaussian wave, acquiring a first falling edge time of the first time-sharing signal and a second falling edge time of the second time-sharing signal, and acquiring a polygon composed of the first falling edge time, the second falling edge time, the first rising edge time, the second rising edge time and the voltage threshold;

And calculating the barycenter coordinates of the polygons to obtain the abscissa coordinates of the barycenter coordinates, and determining the compensated flight time according to the abscissa coordinates.

In a second aspect, the present application also provides a laser radar walking error compensation device, including:

The signal acquisition module is used for acquiring laser signals reflected by the laser radar from the target object;

the preprocessing module is used for processing the laser signals according to the set voltage threshold value to obtain corresponding signal processing data;

The error calculation module is used for calculating an error compensation value of the flight time of the laser signal according to the signal processing data;

And the compensation module is used for compensating the flight time according to the error compensation value to obtain the compensated flight time.

In a third aspect, the present application also provides a lidar device, comprising a processor and a memory, the memory storing a computer program, which when run on the processor performs the lidar walking error compensation method.

In a fourth aspect, the present application also provides a readable storage medium storing a computer program which, when run on a processor, performs the laser radar walking error compensation method.

Drawings

In order to more clearly illustrate the technical solutions of the present invention, the drawings that are required for the embodiments will be briefly described, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope of the present invention. Like elements are numbered alike in the various figures.

FIG. 1 shows a schematic flow chart of a laser radar walking error compensation method according to an embodiment of the application;

FIG. 2 shows a schematic diagram of a laser ranging light path according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a laser signal and a time-sharing signal according to an embodiment of the present application;

FIG. 4 shows a schematic diagram of a laser signal according to an embodiment of the present application;

fig. 5 shows a schematic structural diagram of a laser radar walking error compensation device according to an embodiment of the application.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.

The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present invention.

The terms "comprises," "comprising," "including," or any other variation thereof, are intended to cover a specific feature, number, step, operation, element, component, or combination of the foregoing, which may be used in various embodiments of the present invention, and are not intended to first exclude the presence of or increase the likelihood of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.

Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the invention belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having a meaning that is the same as the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in connection with the various embodiments of the invention.

The technical scheme of the application is applied to error compensation during laser radar ranging, and laser signals reflected by the laser radar are obtained; processing the laser signal according to a set voltage threshold value to obtain corresponding signal processing data; and processing the signal processing data to obtain an error compensation value of the flight time of the laser signal, and compensating the flight time according to the error compensation value to obtain the compensated flight time. Thereby obtaining the correct distance.

The technical scheme of the application is described in the following specific embodiments.

Example 1

As shown in fig. 1, the laser radar walking error compensation method of the present embodiment includes:

step S100, a laser signal reflected by the laser radar from the target object is acquired.

The laser radar determines the distance between the transmitting end and the reflecting section by transmitting laser and then receiving the laser signal fed back, so that the distance measuring operation is completed, and the distance measuring operation is also performed in the embodiment in this way.

As shown in fig. 2, TX is the transmitting end of the laser, and RX is the receiving end of the reflected laser signal, and this embodiment mainly processes the laser signal received at RX to complete error compensation.

Step 200, according to the set voltage threshold, processing the laser signal to obtain corresponding signal processing data.

In this embodiment, the received laser signal is processed by presetting voltage thresholds, where the number of the preset voltage thresholds is two, and the two voltage thresholds are different from each other, so as to process the received laser signal to obtain a time-sharing signal corresponding to the laser signal.

It can be understood that the received laser signal is actually an electrical signal varying with voltage, the time-sharing signal obtained by setting the voltage threshold is delimited by the voltage threshold, and when the voltage threshold is smaller than the time-sharing signal, the value is recorded as 0, and when the voltage threshold is larger than the voltage threshold, the value is recorded as 1, so that the laser signal of the wave band can be converted into a flat time-sharing signal.

Wherein, because the present embodiment sets two voltage thresholds, two time-sharing signals are obtained.

For convenience of subsequent calculation, in this embodiment, the first voltage threshold is smaller than the second voltage threshold, the first voltage threshold is denoted as th1, the second voltage threshold is denoted as th2, the first time-sharing signal generated through the first voltage threshold is denoted as time-sharing 1, and the second time-sharing signal generated through the second voltage threshold is denoted as time-sharing 2.

As shown in fig. 3, the correspondence between the laser signal and the time-sharing signal can be seen that the two obtained time-sharing signal patterns are different by setting different voltage thresholds. The first rising edge time and the second rising edge time can be obtained according to the forms of the two time-sharing signals.

The rising edge time refers to the time when the value changes from 0 to 1, and the time corresponds to the time when the straight line in the number direction is reflected on the image.

The laser signal received in this embodiment is a gaussian-like wave, so the two rising edge moments can also be calculated based on a one-dimensional gaussian formula and then based on the average value of the received gaussian wave.

Specifically, if the gaussian wave mean value is μ, the following calculation formula exists:

Where th1 is a first voltage threshold, th2 is a second voltage threshold, σ is a standard deviation of a gaussian wave, μ is a mean value of the gaussian wave, a is a constant parameter, pulse1 is a first rising edge time, pulse2 is a second rising edge time, and according to the above formula, the corresponding first rising edge time, second rising edge time, pulse2, and a difference between the two rising edge times can be calculated directly from the received data.

Step S300, calculating an error compensation value of the flight time of the laser signal according to the signal processing data.

Wherein the difference between the two rising edges can reflect the sigma of different gaussian waves. I.e. can reflect different waveforms. The essential reason for the walking error is that the walking error is caused by different waveforms, so that the relation between the walking error and the ranging compensation value is equivalent to the relation between the ranging compensation value and the waveform, and the walking error can be solved according to the relation constructed by the relation.

For this purpose, a walking error compensation model is constructed, by means of which the corresponding error compensation value is obtained.

The expression of the model is as follows: f (x) =ae ^Bx+C;

In this embodiment, the time difference between the first rising edge time and the second rising edge time is taken as an independent variable to be input into the walking error compensation model to calculate a corresponding compensation value, the first rising edge time is denoted as pulse1, the second rising edge time is denoted as pulse2, and the difference is input into the model to obtain F (pulse 1-pulse 2) =ae ^B(pulse1 ^-pulse2)+C.

In this embodiment, different received signal waveforms are collected, different signal amplitudes are covered, and compensation is performed with the rising edge of the saturated waveform as a reference. Wherein, the A, B, C fitting coefficients in the model are obtained according to polynomial fitting, that is, before practical use, multiple groups of data can be obtained by calibration, each coefficient required in the above formula can be obtained by fitting according to the obtained data, and the calculating process of how to fit is not important, but is not described too much.

And step S400, compensating the flight time according to the error compensation value to obtain the compensated flight time.

Since the abscissa of the waveform diagram of the obtained laser signal is time, the compensation value F calculated by the model is also time, and the actually measured flight time can be compensated according to the compensation value, so as to obtain the compensated time. And then carrying out subsequent calculation according to the compensated time to obtain a compensated ranging result.

For example, actual time + compensation time = measured time of flight, the measured time of flight minus the calculated compensation time yields the actual time. From this actual time and the laser signal speed, a measured build-up can be obtained.

In this embodiment, the gaussian waves with different variances can be represented by the double-front difference, so that signals with different amplitudes can be represented, so that the double-front difference and the compensation value have a one-to-one correspondence, and then the two relations are obtained by fitting according to the data, namely, coefficients in a model are obtained by fitting. In actual use, the compensation value can be obtained according to the model, so that the accurate distance can be calculated.

In the case of saturation of the echo and distortion of the waveform, the calculation method can be further improved, and it is known that the two voltage thresholds are set to be values, and the voltage threshold is not changed after being set, so th2-th1 is a fixed value, andThat is, the slope of the rising edge is expressed, and the relationship between the slope and the compensation value is established, so that the echo saturation condition can be applied, and therefore the following is trueBy introducing the walking error model, the/>

Similarly, since the above-described ABC three coefficients require coefficient values obtained by re-fitting the independent variables to obtain the coefficients using slopes, a model different from the model using pulse1-pulse2 as the dependent variables is constructed, and thus the compensation value is calculated using a different model in each case. The calculation mode of the passing slope can be considered as embedding the variation of the calculation mode of the difference according to the double fronts, and the slope of the signal fronts can represent signals with different amplitudes, so that the slope of the echo and the compensation value have a one-to-one correspondence, and then the relationship between the two is obtained according to data fitting, and the coefficient of the model can also be obtained, so that the compensation value is calculated in actual use, and the flight time is compensated.

The inconsistent ranging of different reflectivities and different distances is mainly caused by walking errors. The walking error is signals with different amplitudes, and after time-sharing processing, errors can occur in time, the measuring time with larger amplitude is earlier, and the measuring time with smaller amplitude is later. According to the embodiment, the walking error compensation model is constructed, and the compensation correction measured value of the error is obtained according to the input information, so that the range inconsistency is improved. Meanwhile, the method provided by the embodiment can be suitable for error compensation calculation during standard Gaussian wave and echo saturation, so that targeted adjustment can be performed according to different conditions, and the calculated compensation value is ensured to be correct. And the laser radar ranging is applied to a plurality of application scenes and technical fields such as automatic driving, unmanned aerial vehicle and the like, and provides a more accurate ranging means, so that the ranging requirements can be better met in related scenes, and the control precision in the scenes is improved.

Example 2

If the resolution of the received signal is high, and the rising edge timing is inaccurate, and thus the errors of pulse1-pulse2 are large, in this case, the present embodiment also provides a centroid method to calculate the peak center to eliminate the heart error, so as to obtain a sufficiently accurate flight time, where the method of the present embodiment is partially different from that of embodiment 1 in step S200 and step S300.

As shown in fig. 4, after processing the received laser signal according to the two voltage thresholds set in embodiment 1, the first and second falling edge timings can be obtained in addition to the first and second rising edge timings described above.

The difference between the first rising edge time and the first falling edge time is the first width1 in fig. 4, and the difference between the second rising edge time and the second falling edge time is the second width2. Thus, a quadrangle can be obtained on the basis of the oscillogram. For ease of calculation, the coordinates of the four points of the quadrilateral may be recorded as (0, 0), (pulse2-pulse1, th2-th 1), (pulse1+width 1, 0), (pulse2-pulse1+width 2, th2-th 1).

By the coordinates of the four points, the centroid coordinates of the quadrangle are obtained, and generally, the quadrangle will be a trapezoid, and the accurate flight time can be obtained according to the abscissa of the centroid coordinates, so that unlike embodiment 1, the centroid method of this embodiment can calculate an accurate measurement distance according to the flight time, without performing the operation of obtaining the error compensation value of the flight time of the laser signal.

For a signal, if it is gaussian-like, the x-axis of the centroid of the series of signals is the same. Based on the principle, signals with different amplitudes can be aligned based on the mass center by calculating the mass center, so that the walking error is corrected, the measurement distance after the correction error can be directly calculated according to the abscissa, and accurate distance measurement is completed.

The embodiment also provides a laser radar ranging method, wherein after the compensated flight time is obtained through the laser radar walking error compensation method, the measurement distance is calculated according to the compensated flight time, so that the accurate ranging operation can be completed.

Example 3

As shown in fig. 5, this embodiment provides a laser radar walking error compensation device, including:

The signal acquisition module 10 is used for acquiring laser signals reflected by the laser radar from the target object;

The preprocessing module 20 is configured to process the laser signal according to a set voltage threshold value to obtain corresponding signal processing data;

an error calculation module 30, configured to calculate an error compensation value of the time of flight of the laser signal according to the signal processing data;

And the compensation module is used for compensating the flight time according to the error compensation value to obtain compensated flight time 40.

The application also provides laser radar equipment, which comprises a processor and a memory, wherein the memory stores a computer program, and the computer program executes the laser radar walking error compensation method when running on the processor.

The application also provides a readable storage medium storing a computer program which when run on a processor performs the laser radar walking error compensation method. The method comprises the following steps: acquiring a laser signal reflected by a laser radar; processing the laser signal according to a set voltage threshold value to obtain corresponding signal processing data; and processing the signal processing data to obtain an error compensation value of the flight time of the laser signal, and compensating the flight time according to the error compensation value to obtain the compensated flight time. Thereby improving the ranging accuracy and solving the problem of inconsistent ranging of targets with different reflectivities.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The apparatus embodiments described above are merely illustrative, for example, of the flow diagrams and block diagrams in the figures, which illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In addition, functional modules or units in various embodiments of the invention may be integrated together to form a single part, or the modules may exist alone, or two or more modules may be integrated to form a single part.

The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a smart phone, a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention.

Claims

1. The laser radar walking error compensation method is characterized by comprising the following steps:

acquiring a laser signal reflected by a laser radar from a target object;

According to the signal processing data, calculating to obtain an error compensation value of the flight time of the laser signal;

2. The method for compensating for walking error of laser radar according to claim 1, wherein there are two voltage thresholds, and processing the laser signal according to the voltage thresholds to obtain corresponding signal processing data comprises:

3. The method for compensating for walking error of laser radar according to claim 2, wherein said processing said signal processing data to obtain an error compensation value of a time of flight of the laser signal comprises:

Acquiring a preset walking error compensation model;

4. The method of claim 3, wherein the step of obtaining the first rising edge time of the first time-division signal and the second rising edge time of the second time-division signal comprises:

acquiring a Gaussian wave average value of the laser signal;

5. The method for compensating for a walking error of a lidar according to claim 3, wherein the expression of the walking error compensation model is:

F(x)＝Ae^Bx+C；

6. The method for compensating for walking error of laser radar according to claim 2, wherein said processing said signal processing data to obtain an error compensation value of a time of flight of the laser signal comprises:

7. The method for compensating for walking error of laser radar according to claim 2, wherein said processing said laser signal according to a set voltage threshold to obtain corresponding signal processing data, further comprises:

8. A lidar walk error compensation device, comprising:

9. A lidar device comprising a processor and a memory, the memory storing a computer program that, when run on the processor, performs the lidar walking error compensation method of any of claims 1 to 7.

10. A readable storage medium, characterized in that it stores a computer program which, when run on a processor, performs the lidar walking error compensation method of any of claims 1 to 7.