A method for evaluating performance of a laser radar target detection based on Monte Carlo simulation

Abstract

The application discloses a kind of based on Monte Carlo simulation laser radar target detection performance evaluation method, comprising: pre-configuring the hardware system parameter of laser radar and optical field structure parameter;Generation spherical equidistant spiral scanning path, the unit vector group of beam pointing of each pulse moment under three-dimensional coordinate system and the range of detection allowed elevation;Randomly generate target initial position and initial motion velocity, and ensure that velocity vector points to the inside of detection hemisphere;Calculate the position vector of target at time, according to different optical field structure setting corresponding threshold judgment method and detection threshold, compared with corresponding time beam vector and judge whether laser radar can successfully detect target at current time;The corresponding result of whether can capture is accumulated and counted;The number of successful detection is divided by total simulation number, i.e. Using the application, the detection performance of laser radar using different structure optical field on random target can be accurately, quickly and expansively evaluated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser radar detection, and particularly relates to a laser radar target detection performance evaluation method based on Monte Carlo simulation. BACKGROUND

[0002] As a new generation of high-precision active detection means, laser radar (LiDAR, Light Detection and Ranging) has significant advantages in autonomous driving, space-based / sea-based surveillance, fine mapping and regional security warning, etc. due to its centimeter-level ranging accuracy, sub-milliradian spatial angle resolution, strong anti-environmental light interference capability, and stable working performance in day and night and multi-weather conditions. Especially in complex environment and high-speed target detection, laser radar can realize fast positioning and identification of unknown targets by actively emitting and receiving specific spatio-temporal modulated structured light field in the scanning process, providing important sensing support for target detection tasks.

[0003] The existing laser radar target detection performance evaluation mainly relies on field test or simplified analytical model. Although the field test is real, it is high in cost, long in period, and limited by weather and scene conditions, and it is difficult to systematically cover all operating states. Although the analytical model is fast in operation, it is often based on the simplified assumptions of ideal axisymmetric conical beam and fixed parameter scene, and cannot accurately describe the characteristics of laser radar using point, two-dimensional line, hollow ring and other structured light fields for detection. It is also difficult to introduce the comprehensive influence of target random spatial motion vector distribution, beam scanning strategy, system parameters (scanning frequency, field of view angle, angle resolution, etc.), resulting in a large deviation between the evaluation results and the real performance.

[0004] Chinese patent documents with publication numbers CN118244287A and CN118243960A respectively propose methods and devices for target detection using structured light field in atmospheric and ocean scattering media, but they only explain that the large spatial distribution characteristics of the structured light field can increase the possibility of detecting targets, and do not perform strict detection performance analysis, which is not practical enough.

[0005] Chinese patent document with publication number CN120254876A proposes a detailed and accurate method for target velocity vector detection using structured light field, but it only analyzes the quasi-static process in a very short time interval in a certain direction, without considering the random target detection process before velocity vector solving, which is not comprehensive enough.

[0006] Therefore, there is an urgent need for a method that can comprehensively consider the multi-parameter coupling effect of lidar, accurately reflect the spatiotemporal scanning characteristics of complex structure light fields, support random moving target scenarios and fast convergence probabilistic statistical analysis, so as to accurately, quickly and repeatably quantitatively evaluate the target detection performance of lidar under different system configurations, light field morphologies and operating conditions. Summary of the Invention

[0007] This invention provides a method for evaluating the performance of lidar target detection based on Monte Carlo simulation. It can comprehensively consider the target's random initial position, random velocity, lidar scanning mode and trajectory, system parameters and detection threshold, and supports multiple structured light field beams to achieve fast, scalable and high-precision lidar target detection performance evaluation.

[0008] A method for evaluating the target detection performance of lidar based on Monte Carlo simulation includes the following steps:

[0009] (1) Pre-configure the hardware system parameters and optical field structure parameters of the lidar, and establish a three-dimensional coordinate system based on the lidar position;

[0010] (2) Based on the hardware system parameters and optical field structure parameters of the lidar, a spherical equidistant spiral scanning path is generated, and the beam pointing unit vector group at each pulse moment in the three-dimensional coordinate system is obtained. And the allowable elevation angle for detection Scope;

[0011] (3) Based on the pre-configured maximum detection range The target's initial position and initial velocity are randomly generated based on the target's motion parameters; the target's initial position is located at... A hemisphere with radius [missing information], and in the detection allowable elevation angle [missing information]. Any location within the range; the initial velocity of the target is within... Random distribution between intervals, The preset target speed limit;

[0012] (4) Detect the generated target initial position vector With the initial velocity vector The relationship between the two is such that the dot product of the two... If the sample is discarded, step (3) is repeated continuously and the detection continues until the dot product is reached. Ensure that the velocity vector points inside the detection hemisphere;

[0013] (5) Calculation time Next target position vector Based on different light field structures, corresponding threshold judgment methods and detection thresholds are set, and corresponding... Beam vector at time step Compare and determine whether the lidar can successfully detect the target at the current moment;

[0014] (6) Repeat step (5) until the detection is successful or the target flies out of the detection area without returning. Then end the single Monte Carlo simulation and accumulate the corresponding results of whether or not the target can be captured.

[0015] (7) Repeat steps (3)-(6) until the preset requirements are met. The performance of the lidar in detecting targets is defined as the number of successful detections divided by the total number of simulations, i.e., the detection probability.

[0016] In step (1), the origin O of the three-dimensional coordinate system is the location of the lidar, the XOY plane is the horizontal ground, and the z-axis is vertically upward.

[0017] In step (1), the light field structure includes a point light source, a two-dimensional linear light source, and a hollow ring light source.

[0018] In this invention, the hardware system parameters include the laser radar scanning rotation speed, laser pulse repetition frequency, maximum detection distance and maximum detection height of the laser radar, and the upper limit of the random motion speed of the target; the optical field structure parameters include the maximum size divergence angle of the beam and the divergence angle of the beam spot.

[0019] In step (2), the corresponding laser trajectory coordinates in the spherical equidistant spiral scanning path are as follows:

[0020] ;

[0021] ;

[0022] ;

[0023] In the formula, For maximum detection range, for The maximum size of the light field at that location, is the independent variable in the parametric equation, corresponding to the polar angle of the lidar beam pointing vector.

[0024] In step (2), the beam pointing to the unit vector group at each pulse moment This corresponds to a complete scanning trajectory from the minimum elevation angle to the maximum elevation angle. When using it, it must be stitched together in a head-to-tail sequence to simulate the continuous reciprocating scanning process of a lidar in actual operation.

[0025] In step (2), the allowable elevation angle is detected. The range is:

[0026] ;

[0027] in, is the maximum detection height, is the maximum detection distance, is the maximum size of the light field at the target position.

[0028] As a preference, in step (3), the minimum speed of the target initial motion speed is limited to 0.1 m / s, which optimizes the extreme long time consumption caused by random speed while approaching the actual state target minimum drift speed.

[0029] In step (5), the time is the discrete sampling point based on the laser pulse repetition frequency , and the minimum sampling time interval is to avoid unnecessary system time and space resource overhead caused by too short time division scale.

[0030] In step (5), the target position vector at time is calculated, and the formula is as follows:

[0031] ;

[0032] wherein, after the target initial motion speed vector is determined, the target moves at a constant speed in a straight line in three-dimensional space.

[0033] In step (5), according to different light field structures, corresponding threshold judgment methods and detection thresholds are set, and the beam vector t at time is compared and judged to determine whether the laser radar can successfully detect the target at the current time, and the specific formula is as follows:

[0034] Point light source:

[0035] ;

[0036] Two-dimensional linear light source:

[0037] ;

[0038] Hollow ring light source:

[0039] ;

[0040] wherein, is the vector norm operator, are the minimum value and the maximum value of the polar angle of the two-dimensional linear light source in space at time , respectively, are the polar angle and the elevation angle of the target position at time , respectively, are the minimum value and the maximum value of the polar angle of the two-dimensional linear light source in space at time The minimum and maximum values of the elevation angle of the two-dimensional linear light source in space at the moment, the light field structure is defined by a plurality of divergence angles, the maximum size of the beam divergence full angle is , and the beam angle spot divergence full angle is .

[0041] As preferred, the simulation is accelerated by multi-process, the random variable selection in all processes conforms to the independent repeated experiment rule, the result is summarized after the end of each process, the accelerated simulation program is run, and accurate and rapid analysis is facilitated.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] The present application can fully combine structured light fields with different shape characteristics and parameters, can automatically set the laser radar scanning track and mode for structured light fields of different shapes, and can generate unknown random motion targets in real application scenarios, accurately and quickly calculate the detection probability of the corresponding laser radar on the target and other detection performances, and has the characteristics of high precision, fast calculation, strong robustness and high scalability. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0045] Figure 1 A flow chart of a laser radar target detection performance evaluation method based on Monte Carlo simulation in an embodiment of the present application.

[0046] Figure 2 A schematic diagram of a specific scene of laser radar work in an embodiment of the present application.

[0047] Figure 3 For three different light field structures in an embodiment of the present application, a convergence trend graph of detection probability with increasing Monte Carlo simulation times. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0049] It should be noted that the features in the following examples and embodiments can be combined with each other as long as there is no conflict.

[0050] As shown in the figure, a laser radar target detection performance evaluation method based on Monte Carlo simulation, specifically comprising the following steps: Figure 1

[0051] (1) Pre-configure the hardware system parameters and light field structure parameters of the laser radar, and establish a three-dimensional coordinate system based on the position of the laser radar.

[0052] The origin O of the three-dimensional coordinate system is the position of the laser radar, the XOY plane is the horizontal ground, and the z-axis direction is vertically upward.

[0053] (2) Based on the hardware system parameters and light field structure parameters of the laser radar, generate a spherical equidistant spiral scanning path, and obtain the unit vector group of the beam pointing direction of each pulse moment in the three-dimensional coordinate system And the range of the detection allowed elevation angle .

[0054] In the spherical equidistant spiral scanning path, the corresponding laser trajectory coordinates are as follows:

[0055] ;

[0056] ;

[0057] ;

[0058] In the formula, is the maximum detection distance, is the maximum size of the light field at , and is the parameter equation independent variable, corresponding to the polar angle of the laser radar beam pointing vector.

[0059] The unit vector group of the beam pointing direction of each pulse moment corresponds to a complete scanning trajectory from the minimum elevation angle to the maximum elevation angle. When used, it needs to be spliced in the order of first and last to simulate the continuous reciprocating scanning process of the laser radar in actual work.

[0060] The range of the detection allowed elevation angle is:

[0061] ;

[0062] Among them, is the maximum detection height, is the maximum detection distance, is the maximum size of the light field at . ​

[0063] (3) Based on the pre-configured maximum detection distance and the target motion parameters randomly generate the target initial position and initial motion speed; the target initial position is located at an arbitrary position on the hemisphere with a radius of and within the detection allowed elevation angle range; the target initial motion speed size is randomly distributed between and is the preset upper limit of the target motion speed.

[0064] (4) Detect the relationship between the generated target initial position vector and the initial motion speed vector If the dot product of the two is , discard the sample and repeatedly step (3) and detect until the dot product is , ensuring that the speed vector points to the inside of the detection hemisphere.

[0065] (5) Calculate the target position vector at time , set the corresponding threshold judgment method and detection threshold according to different light field structures, and compare with the corresponding beam vector at time to determine whether the laser radar can successfully detect the target at the current time.

[0066] Time is a discrete sampling point based on the laser pulse repetition frequency , and the minimum sampling time interval is to avoid unnecessary system time and space resource overhead caused by too short time division scales.

[0067] Calculate the target position vector at time , the formula is as follows:

[0068] ;

[0069] Wherein, the target initial motion speed vector moves at a constant speed in a straight line in three-dimensional space.

[0070] Set the corresponding threshold judgment method and detection threshold according to different light field structures, and compare with the corresponding beam vector at time t to determine whether the laser radar can successfully detect the target at the current time, the specific formula is: Point light source:

[0071]

[0072] ;

[0073] ​​​​Two-dimensional linear light source:

[0074] ;

[0075] Hollow annular light source:

[0076] ;

[0077] wherein, is the vector norm operator, are respectively the minimum and maximum values of the polar angle of the two-dimensional linear light source in space at the moment of transmission, are respectively the polar angle and the elevation angle of the target position at the moment, are respectively the minimum and maximum values of the elevation angle of the two-dimensional linear light source in space at the moment of transmission, the light field structure is defined by a plurality of divergence angles, the maximum size of the beam divergence full angle is , and the beam angle spot divergence full angle is .

[0078] (6) Repeat step (5) until the detection is successful or when the target does not return to the flight detection area, end the single Monte Carlo simulation, and accumulate the count of the corresponding capture results.

[0079] (7) Repeat steps (3)-(6) until the preset requirement is met, and the laser radar detection target performance is defined as the number of successful detections divided by the total number of simulations, i.e. the detection probability.

[0080] The corresponding laser radar working specific scene of the application is shown in Figure 2 , the laser radar is located at the origin of the three-dimensional space coordinate system, and a certain structure light field (point light source, two-dimensional linear light source or hollow annular light source, and the light field shape and parameters do not change during scanning) and its corresponding trajectory mode are scanned. The random target starts from any position on a sphere with a radius of , and moves at a uniform speed (randomly between the maximum and minimum speeds). The Monte Carlo method can be used to evaluate the detection performance of the laser radar on such random targets without prior information.

[0081] In this embodiment, the laser radar system parameters are set as follows: laser pulse repetition frequency 50 kHz, maximum rotation speed of laser radar 2 rad / s and 40 rad / s, respectively, and the structure light field parameter settings are shown in Table 1.

[0082] Table 1

[0083]

[0084] The upper and lower limits of the random target speed size are set as (0, 50 m / s], and whether the laser radar can detect such a random target during detection is determined, and the probability of successful detection converges with the number of independent Monte Carlo times as shown in Figure 3 , wherein the horizontal coordinate is the number of independent Monte Carlo times, the vertical coordinate is the probability of successful detection, the left graph corresponds to a laser radar rotating speed of 2 rad / s, and the right graph corresponds to a laser radar rotating speed of 40 rad / s. It can be seen that for the three light fields, the detection probability appears a stable convergence trend with the increase of the Monte Carlo times, and the convergence path and the respective convergence value are inconsistent, indicating that the method has high feasibility and stability.

[0085] The above embodiments have described the technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the present application. Any modification, supplement and equivalent replacement made within the principle range of the present application shall be included in the protection range of the present application.

Claims

1. A method for evaluating the target detection performance of lidar based on Monte Carlo simulation, characterized in that, Includes the following steps: (1) Pre-configure the hardware system parameters and optical field structure parameters of the lidar, and establish a three-dimensional coordinate system based on the lidar position; (2) Based on the hardware system parameters and optical field structure parameters of the lidar, a spherical equidistant spiral scanning path is generated, and the beam pointing unit vector group at each pulse moment in the three-dimensional coordinate system is obtained. And the allowable elevation angle for detection Scope; (3) Based on the pre-configured maximum detection range The target's initial position and initial velocity are randomly generated based on the target's motion parameters; the target's initial position is located at... A hemisphere with radius [missing information], and in the detection allowable elevation angle [missing information]. Any location within the range; the initial velocity of the target is within... Random distribution between intervals, The preset target speed limit; (4) Detect the generated target initial position vector With the initial velocity vector The relationship between the two is such that the dot product of the two... If the sample is discarded, step (3) is repeated continuously and the detection continues until the dot product is reached. Ensure that the velocity vector points inside the detection hemisphere; (5) Calculation time Next target position vector Based on different light field structures, corresponding threshold judgment methods and detection thresholds are set, and corresponding... Beam vector at time step Compare and determine whether the lidar can successfully detect the target at the current moment; (6) Repeat step (5) until the detection is successful or the target flies out of the detection area without returning. Then end the single Monte Carlo simulation and accumulate the corresponding results of whether or not the target can be captured. (7) Repeat steps (3)-(6) until the preset requirements are met. The performance of the lidar in detecting targets is defined as the number of successful detections divided by the total number of simulations, i.e., the detection probability.

2. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (1), the origin O of the three-dimensional coordinate system is the location of the lidar, the XOY plane is the horizontal ground, and the z-axis is vertically upward.

3. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (1), the light field structure includes a point light source, a two-dimensional linear light source, and a hollow ring light source.

4. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (2), the corresponding laser trajectory coordinates in the spherical equidistant spiral scanning path are as follows: ； ； ； In the formula, For maximum detection range, for The maximum size of the light field at that location, is the independent variable in the parametric equation, corresponding to the polar angle of the lidar beam pointing vector.

5. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (2), the beam pointing to the unit vector group at each pulse moment This corresponds to a complete scan trajectory from the minimum elevation angle to the maximum elevation angle.

6. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (2), the allowable elevation angle is detected. The range is: ； in, For the maximum detection altitude, For maximum detection range, for The maximum size of the light field at that location.

7. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (5), time Based on laser pulse repetition frequency f The discrete sampling points have a minimum sampling time interval of . .

8. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (5), the time is calculated. Next target position vector The formula is as follows: ； Among them, the target's initial velocity vector Once determined, it moves at a constant linear velocity in three-dimensional space.

9. The method for evaluating the target detection performance of lidar based on Monte Carlo simulation according to claim 1, characterized in that, In step (5), corresponding threshold judgment methods and detection thresholds are set according to different light field structures, and corresponding... Beam vector at time step The formula for comparing and determining whether the lidar can successfully detect the target at the current moment is as follows: Point light source: ； Two-dimensional linear light source: ； Hollow ring light source: ； in, The modulo operator for vectors, They are respectively The minimum and maximum values ​​of the polar angle when a two-dimensional linear light source propagates in space at a given time. They are respectively The polar angle and elevation angle of the target position at that moment. They are respectively The minimum and maximum elevation angles of a two-dimensional linear light source propagating in space at a given time are given. The light field structure is defined by multiple divergence angles, and the maximum divergence angle of the beam is given. The beam divergence angle is the full angle. .

Images