A method for simulating radar point cloud and echo based on spatial features

Abstract

The application discloses a radar point cloud and echo simulation method based on spatial features, which comprises: coordinate system conversion to determine the relative relationship, discrete target edge acquisition of detection points, occluded data removal of detection point screening, multi-path detection point acquisition to simulate multi-path effects, and radar signal acquisition to simulate linear frequency modulation signals. According to the distance resolution and angle resolution, the target edge is discretized into detection points, the occluded part is removed, ideal point cloud data is obtained, and finally the echo signal containing the ground multi-path effect is generated. Compared with the radar sensor development board for collecting measured data, the application can overcome the problems of fixed scene setting and limited experimental environment, quantitatively represent the spatial characteristics of radar point cloud in a multi-target complex scene through detection point acquisition and detection point screening, and thus realize high-flexibility and low-cost simulation of continuous wave radar point cloud data and echo signals.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of radar signal processing, and particularly relates to a radar point cloud and echo simulation method based on spatial features, which is suitable for vehicle driving, autonomous parking, unmanned aerial vehicle taxiing and the like, and simulation of frequency modulated continuous wave (FMCW) radar point cloud data and echo signals. BACKGROUND

[0002] The frequency modulated continuous wave (FMCW) radar is often used in the perception of the surrounding environment in the scenes of vehicle driving, autonomous parking, unmanned aerial vehicle taxiing and the like, can acquire and analyze the target information around in real time, and plays a vital role in the fields of military, civil and scientific research. The ground collision perception and warning technology based on the frequency modulated continuous wave radar is one of the effective ways to improve the efficiency of the out-of-service and ensure the safety of driving, and the radar point cloud data and echo signals provide decision basis for the autonomous obstacle avoidance system of unmanned vehicles and unmanned aerial vehicles.

[0003] At present, the collision perception and warning technology based on the continuous wave radar needs a large amount of point cloud data, and the development and performance verification of the autonomous obstacle avoidance algorithm mainly use public data sets or radar sensor development boards for real-time sampling. However, the public data set is a fixed scene setting, which cannot match the features of various autonomous obstacle avoidance algorithms, and the verification effect is difficult to achieve the best; and some methods use radar sensor development boards to measure and sample radar echoes, and then obtain point cloud data through signal processing, but the scene setting of this method is limited by the experimental environment, and the cost is high, which cannot meet the needs of the development and verification of various algorithms.

[0004] The scene setting of the simulated point cloud is more flexible, and under the premise that the accuracy meets the demand, it is more suitable for the development and performance verification of various autonomous obstacle avoidance algorithms in detection scenes. In a multi-target scene, due to the complexity of the detection scene, the accuracy and robustness of the simulated point cloud are difficult to meet the real demand. Therefore, it is necessary to study an effective continuous wave radar point cloud data and echo signal simulation method, consider the spatial correlation between adjacent detection points, determine an accurate line-of-sight detection point screening method, and realize high-flexibility and low-cost generation of algorithm verification data. SUMMARY

[0005] The purpose of the present application is to provide a radar point cloud and echo simulation method based on spatial features, so as to quantitatively represent the spatial characteristics of the radar point cloud in a multi-target complex scene, and realize high-flexibility and low-cost generation of point cloud data.

[0006] In order to achieve the above-mentioned task, the present application adopts the following technical scheme:

[0007] A radar point cloud and echo simulation method based on spatial features, comprising:

[0008] Modeling a detection target in a frequency-modulated continuous wave radar detection scene in a reference coordinate system, modeling the detection target as a polygon composed of multiple vertices; determining position parameters and velocity parameters of the radar, the detection target and the vertices in the reference coordinate system;

[0009] Constructing a radar rectangular coordinate system and a radar polar coordinate system, determining the distance and azimuth angle of all vertices of each detection target in the radar polar coordinate system by using the position parameters and velocity parameters of the radar, the detection target and the vertices in the reference coordinate system;

[0010] For each detection target, sorting all its vertices, screening out demarcation vertices according to the azimuth angle of the vertices, and determining the vertex set as a line-of-sight vertex based on the distance between the vertex sets formed by the vertices between and outside the demarcation vertices and the radar, and discretizing the target edge between adjacent line-of-sight vertices into a series of detection points, and then determining the position parameters, radial velocity and azimuth angle of each detection point relative to the radar;

[0011] For each group of adjacent detection points on each detection target, the region between the detection points is taken as a shielding interval, and whether each detection point of other targets is outside the line-of-sight range due to being shielded by the shielding interval is calculated in turn, so as to screen out all detection points located within the line-of-sight range, which constitute an ideal point cloud of the radar detection scene, denoted as real detection points;

[0012] Based on the multipath effect of the radar signal in the detection scene, three types of multipath detection points corresponding to each real detection point in the ideal point cloud are obtained, and the position parameters, radial velocity and azimuth angle of each type of multipath detection point are determined;

[0013] Determining the radar echo signal matrix corresponding to the real detection points and the three types of multipath detection points, thereby simulating and generating radar echo signals.

[0014] Further, the reference coordinate system takes the ground as the xoy plane, the radar rectangular coordinate system takes the position of the radar as the origin o', and the normal of the radar antenna array as the y' axis; the radar polar coordinate system takes o' as the pole, the y' axis as the polar axis, and clockwise as the positive direction of the polar angle; according to the conversion relationship between the reference coordinate system and the radar rectangular coordinate system, and the corresponding relationship between the radar rectangular coordinate system and the radar polar coordinate system, the distance and azimuth angle of all vertices of each detection target in the radar polar coordinate system are obtained.

[0015] Further, the radar rectangular coordinate system and the radar polar coordinate system are constructed, and the position parameters and the speed parameters of the radar, the detected targets and the vertexes in the reference coordinate system are used to determine the distance and the azimuth angle of all the vertexes of each detected target in the radar polar coordinate system, including:

[0016] Firstly, all the vertexes of each detected target are arranged in the radar polar coordinate system in a clockwise order, two vertexes corresponding to the maximum azimuth angle and the minimum azimuth angle are selected as the demarcation vertexes, the vertexes between the demarcation vertexes and the vertexes outside the demarcation vertexes form two vertex sets respectively; the average value of the distances r ij of all the vertexes in each vertex set from the radar is calculated, and then the vertex set with the smaller average distance value contains the sight distance vertex, the target edge between the adjacent sight distance vertexes is the sight distance edge that can be detected by the radar, and is taken as the discrete object of the detection points;

[0017] Secondly, the target edge between the adjacent sight distance vertexes on each detected target is discretized into detection points X k according to the preset distance resolution r res and the angle resolution θ res .

[0018] Finally, the radial velocity v k of the detection points relative to the radar on the line connecting the detection points and the radar is determined according to the azimuth angle θ k of the detection points X k and the speed of the detected target in the radar rectangular coordinate system, the radial velocity is defined as positive when the detection points are close to the radar, and the radial velocity of the detection points X k on the target edge is obtained; and the distance r k , the radial velocity v k , the azimuth angle θ k and the height h k of all the detection points X k relative to the radar are determined.

[0019] Further, the target edge between the adjacent sight distance vertexes on each detected target is discretized into detection points X k according to the preset distance resolution r res and the angle resolution θ res , including:

[0020] For any group of adjacent sight distance vertexes on a detected target, the distance of one vertex is r m , the azimuth angle is θ m , and the height is h m , the distance of another vertex is r n , the azimuth angle is θ n , and the height from the ground is h nThen the range of the target edges between the two is Δr=|r m -r n |, angular range Δθ=|θ m -θ n |, Detection point X on the edge of the target k Relative to the radar distance r k With azimuth θ k The relationship can be represented as:

[0021]

[0022] The method of discretizing the target edge into detection points can be divided into two categories:

[0023] When |Δr / r res |>|Δθ / θ res At that time, the detection point X on the edge of the target k The number of N1 = Δr / r res +1; when |Δr / r res |≤|Δθ / θ res At that time, the detection point X i The number of them is N2 = Δθ / θ res +1; Detection point X k distance r k =k·r res +min{r m ,r n}, at a height of h above the ground k =k·|h m -h n | / (N1-1)+min{h m ,h n}, where k represents the k-th detection point, k = 0, 1, ..., (N1-1), and the azimuth angle θ of the detection point is calculated according to the above formula. k .

[0024] Furthermore, for each set of adjacent detection points on a detection target, the region between the detection points is taken as the occlusion interval, and the process of sequentially calculating whether each detection point of other targets will be occluded by the occlusion interval and thus outside the line-of-sight range includes:

[0025] Let A and B be two adjacent detection points on the target edge between any set of adjacent line-of-sight vertices. The region between these two detection points A and B is defined as the blocking interval AB. Let the distances of A, B, and P relative to the radar be r, respectively. a r b r p The azimuth angles are θ a θ b θp The height values ​​are h a h b h p The condition under which the probe point P is occluded by the occluded interval AB is:

[0026] Condition 1: In the angle domain, P lies within the angle range of AB, that is:

[0027] (θ a -θ p )(θ b -θ p )≤0

[0028] Condition 2: In the angle-distance domain, P is located "behind" AB. Draw PP0 perpendicular to AB through point P, with the foot of the perpendicular denoted as P0. This condition is equivalent to the vector... The distance value is greater than or equal to the vector The distance value, where and The expression is:

[0029]

[0030] Condition 3: In the distance-height domain, the slope coefficient k of P. p The slope coefficient k is less than or equal to the occlusion interval AB. ab , i.e., k p ≤k ab Since the distance between adjacent detection points is extremely small, the slope coefficient of the occlusion interval is approximately the average of the slope coefficients of adjacent detection points, therefore k p and k ab The expression is:

[0031]

[0032] If conditions one through three are met simultaneously, then P is blocked by AB and is outside the line of sight.

[0033] Furthermore, based on whether the transmitted and scattered radar signals are reflected by the ground, multipath signal propagation paths are divided into three categories: "radar-ground-target-ground-radar", "radar-target-ground-radar", and "radar-ground-target-radar". Therefore, each real detection point T in the ideal point cloud corresponds to one of the three types of multipath detection points: the first type of multipath detection point T1, the second type of multipath detection point T2, and the third type of multipath detection point T3.

[0034] The distance r0, radial velocity v0, azimuth angle θ0 and height h0 of the real detection point T relative to the radar, a plane rectangular coordinate system XOY is established in the plane perpendicular to the ground, the projection point R0 of the radar R on the ground is taken as the origin O of the plane rectangular coordinate system, the projection point of the real detection point T on the ground is denoted as T0, and the projection height is h R Then the X axis points from R0 to T0, and the Y axis points from R0 to R; therefore, the position coordinates of the radar R are (0, h R ), the position coordinates of the real detection point T are (r0, h0), and the position coordinates of the reflection point G of the radar signal on the ground are (r0h R / (h0+h R ), 0); within a short time Δt of the detection target motion, it can be approximately considered that the motion state of the detection target remains unchanged, that is, the real detection point performs uniform linear motion, and the coordinates of the position T′ reached by the real detection point are (r0-v0Δt, h0); the positions reached by T1, T2 and T3 are denoted as T′1, T′2 and T′3;

[0035] For the first type of multi-path detection point T1, since T1 and T, T′1 and T′ are symmetrical about the X axis, the distance r1 of T1 relative to the radar is |RT1| = |RG| + |TG|, the radial velocity v1 of T1 is equal to the radial velocity v0 of the real detection point T, and the azimuth angle θ1 of T1 is determined according to the distance r1;

[0036] For the second type of multi-path detection point T2, T2 is on the extension line of RG and |RT2| = 1 / 2(|RG| + |TG| + |RT|), the position parameters and the azimuth angle θ2 of T2′ are calculated according to the position parameters of T2, then the distance r2 of T2 is |RT2|, and the radial velocity v2 of T2 is v2 = v0·|T2T′2| / |TT′|;

[0037] For the third type of multi-path detection point, T3 is on the extension line of RT and |RT3| = 1 / 2(|RG| + |TG| + |RT|), the position parameters and the azimuth angle θ3 of T3′ are calculated according to the position parameters of T3, then the distance r3 of T3 is |RT3|, and the radial velocity v3 of T3 is v3 = v0·|T3T′3| / |TT′|.

[0038] Further, a detection point Q represents a real detection point or a certain multi-path detection point, the distance of the detection point Q relative to the radar is r, the radial velocity is v, and the azimuth angle is θ; for the m q th array element, the n q th echo pulse and the i q th signal sampling point, the expression of the signal time delay τ is:

[0039]

[0040] Wherein, the speed of light is c, the element spacing is d, and the signal duration is T. r The signal sampling frequency is f s Fast time t = (i q -1) / f s Then any element S in the echo signal matrix q (m q ,n q i q The expression for ) is:

[0041]

[0042] In the above formula, the imaginary unit is j, the signal bandwidth is B, and the signal carrier frequency is f. c ;

[0043] After obtaining the echo signal matrix S corresponding to all real detection points and the three types of multipath detection points, q Then, the echo signal matrix S of all real detection points and corresponding three types of multipath detection points within the radar beam illumination range is... q By summing the signals, we obtain the frequency-modulated continuous wave radar echo signal S for the detection scenario.

[0044] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor executes the computer program, it implements the radar point cloud and echo simulation method based on spatial features.

[0045] A computer-readable storage medium storing a computer program; when executed by a processor, the computer program implements the radar point cloud and echo simulation method based on spatial features.

[0046] Compared with the prior art, the present invention has the following technical features:

[0047] Compared to radar sensor development boards that collect measured data, this invention can overcome the problems of fixed scene settings and limited experimental environment. By acquiring and filtering detection points, it can quantitatively characterize the spatial characteristics of radar point clouds in complex multi-target scenes, thereby achieving highly flexible and low-cost simulation of continuous wave radar point cloud data and echo signals. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of a radar point cloud data and echo signal simulation method in one embodiment of the present invention;

[0049] Figure 2 A schematic diagram of the detection scene and radar beam direction;

[0050] Figure 3 This is a schematic diagram of the coordinate system transformation result;

[0051] Figure 4 Result diagram for detection point acquisition;

[0052] Figure 5 Result diagram for ideal point cloud simulation;

[0053] Figure 6 Constant false alarm rate detection result diagram for echo signal range-doppler feature map. DETAILED DESCRIPTION

[0054] The application provides a radar point cloud and echo simulation method based on spatial features to generate ideal point clouds and frequency-modulated continuous wave radar echoes in a multi-target detection scene, mainly including the following steps:

[0055] Step 1, modeling the detection targets in the frequency-modulated continuous wave radar detection scene in a reference coordinate system, modeling the detection targets as polygons composed of multiple vertices; determining the position parameters and velocity parameters of the radar, the detection targets and the vertices in the reference coordinate system.

[0056] For a frequency-modulated continuous wave radar in a detection scene with a height of h R from the ground, there are N T detection targets around it; in order to generate the radar point cloud and echo data of the detection scene, the ground is taken as the xoy plane to establish a reference coordinate system, the position coordinates of the radar in the x and y axes of the reference coordinate system are marked as (x0, y0), the velocity is marked as (v x0 , v y0 ), and the angle of the normal of the radar antenna array relative to the y axis clockwise is marked as α; the velocity of the i-th detection target is (v xi , v yi ), where i = 1, 2,..., N T , each type of detection target is modeled as a different polygon composed of multiple vertices, the position coordinates of the j-th vertex of the i-th detection target are (x ij , y ij ), and the height of the vertex from the ground is h ij , where j = 1, 2,..., N Pi , N Pi represents the number of vertices contained in the polygon corresponding to the i-th detection target.

[0057] Step 2, constructing a radar rectangular coordinate system and a radar polar coordinate system, using the position parameters and velocity parameters of the radar, the detection targets and the vertices in the reference coordinate system to determine the distance and azimuth angle of all vertices of each detection target in the radar polar coordinate system.

[0058] A radar rectangular coordinate system x'o'y' is established with the radar position as the origin o' and the normal of the radar antenna array as the y' axis, and the angle of the radar rectangular coordinate system relative to the reference coordinate system is clockwise rotation angle a; the position coordinates (x ij ,y ij ) of all vertices of each detection target in the reference coordinate system are converted into the position coordinates (x′ ij ,y′ ij ) in the radar rectangular coordinate system, and the velocities (v xi ,v yi ) of all detection targets in the reference coordinate system are converted into the velocities (v′ xi ,v′ yi ) in the radar rectangular coordinate system, that is

[0059]

[0060] A radar polar coordinate system is established with o' as the pole, y' as the polar axis and clockwise as the polar angle positive direction, and the expression of the distance r ij and the azimuth angle θ ij of all vertices of each detection target in the radar polar coordinate system is:

[0061]

[0062] Step 3, for each detection target, after sorting all vertices, the demarcation vertices are screened according to the azimuth angle of the vertices, and the vertex set serving as the visual distance vertex is determined based on the distance of the vertex set formed by the vertices between and outside the demarcation vertices and the radar, and the target edge between adjacent visual distance vertices is discretized into a series of detection points, and then the position parameters (including the distance relative to the radar and the height from the ground) of each detection point relative to the radar, the radial velocity and the azimuth angle are determined.

[0063] First, all vertices of each detection target are arranged in the radar polar coordinate system in a clockwise order, and the two vertices corresponding to the maximum azimuth angle and the minimum azimuth angle are selected as the demarcation vertices, and the vertices between the demarcation vertices and the vertices outside the demarcation vertices form two vertex sets; the average value of the distance r ij of all vertices in each vertex set from the radar is calculated, and then the vertices contained in the vertex set with a smaller average distance are the visual distance vertices, and the target edge between adjacent visual distance vertices is the visual distance edge that can be detected by the radar, which is the object of discretization of the detection points.

[0064] Secondly, the target edge between adjacent visual distance vertices on each detection target is discretized into detection points X k according to the preset distance resolution r res and angle resolution θ res , and specifically:

[0065] For any pair of adjacent line-of-sight vertices on a certain detection target, let the distance between one of the vertices be r. m The azimuth angle is θ m The height is h m The distance to the other vertex is r. n The azimuth angle is θ n The height above the ground is h n Then the range of the target edges between the two is Δr=|r m -r n |, angular range Δθ=|θ m -θ n |, Detection point X on the edge of the target k Relative to the radar distance r k With azimuth θ k The relationship can be represented as:

[0066]

[0067] The method of discretizing the target edge into detection points can be divided into two categories:

[0068] When |Δr / r res |>|Δθ / θ res At that time, the detection point X on the edge of the target k The number of N1 = Δr / r res +1; when |Δr / r res |≤|Δθ / θ res At that time, the detection point X i The number of them is N2 = Δθ / θ res +1; Detection point X k distance r k =k·r res +min{r m ,r n}, at a height of h above the ground k =k·|h m -h n | / (N1-1)+min{h m ,h n}, where k represents the k-th detection point, k = 0, 1, ..., (N1-1), and the azimuth angle θ of the detection point is calculated according to formula (3). k .

[0069] Finally, based on the detection point X k azimuth angle θ k and the velocity (v′) of the target in the radar Cartesian coordinate system. xi ,v′ yi Determine the component of the velocity of the detection point relative to the radar along the line connecting the two, i.e., the radial velocity v.k Define the radial velocity of a detection point as positive when it approaches the radar; then the detection point X on the edge of the target... k radial velocity v k =-(v′) xi sinθ k +v′ yi cosθ k At this point, the distance rk and radial velocity v of all detection points Xk relative to the radar are... k Azimuth θ k and height h above the ground k All have been obtained.

[0070] Step 4: For each target, for all adjacent sets of detection points, the area between the detection points is taken as the occlusion interval. The detection points of other targets are calculated in turn to determine whether they will be occluded by the occlusion interval and fall outside the line of sight. This process filters out all detection points within the line of sight. These detection points constitute the ideal point cloud of the radar detection scene and are recorded as the real detection points.

[0071] Let A and B be two adjacent detection points on the target edge discrete between any pair of adjacent line-of-sight vertices on the target. Let the region between these two detection points A and B be the occlusion interval AB. For all detection points P of other targets, determine whether they will be occluded by the occlusion interval AB and thus be outside the line-of-sight range.

[0072] Let the distances of A, B, and P relative to the radar be r, respectively. a r b r p The azimuth angles are θ a θ b θ p The height values ​​are h a h b h p The condition under which the probe point P is occluded by the occluded interval AB is:

[0073] Condition 1: In the angle domain, P lies within the angle range of AB, that is:

[0074] (θ a -θ p )(θ b -θ p )≤0 (4)

[0075] Condition 2: In the angle-distance domain, P is located "behind" AB. Draw PP0 perpendicular to AB through point P, with the foot of the perpendicular denoted as P0. This condition is equivalent to the vector... The distance value is greater than or equal to the vector The distance value, where and The expression is:

[0076]

[0077] Condition 3: In the distance-height domain, the slope coefficient k of P. p The slope coefficient k is less than or equal to the occlusion interval AB. ab , i.e., k p ≤k ab Since the distance between adjacent detection points is extremely small, the slope coefficient of the occlusion interval is approximately the average of the slope coefficients of adjacent detection points, therefore k p and k ab The expression is:

[0078]

[0079] If conditions one through three are met simultaneously, then P is blocked by AB and is outside the line of sight.

[0080] The above line-of-sight range determination process is performed sequentially on all detection points of other detection targets using all obstruction ranges of each detection target, and all detection points within the line-of-sight range are selected. These detection points constitute the ideal point cloud of the radar detection scene and are denoted as real detection points. Each real detection point includes the distance relative to the radar, radial velocity, azimuth angle, and height above the ground.

[0081] Step 5: Based on the multipath effect of radar signals in the detection scenario, obtain the three types of multipath detection points corresponding to each real detection point in the ideal point cloud, and determine the position parameters, radial velocity, and azimuth angle of each type of multipath detection point.

[0082] In the detection scenario, the frequency-modulated continuous wave radar transmits frequency-modulated continuous waves, and the received direct-scattered echo signal from the target corresponds to the real detection point in the ideal point cloud. However, due to the reflective characteristics of the ground in the detection scenario, the radar receiver also receives multipath echo signals scattered by the target and reflected by the ground, which are equivalently modeled as radar echo signals from multipath detection points. Based on whether the transmitted and scattered radar signals are reflected by the ground, the multipath signal propagation paths are divided into three categories: "radar-ground-target-ground-radar", "radar-target-ground-radar", and "radar-ground-target-radar". Therefore, each real detection point T in the ideal point cloud obtained in step 4 corresponds to one of the three types of multipath detection points, namely, the first type of multipath detection point T1, the second type of multipath detection point T2, and the third type of multipath detection point T3.

[0083] The distance r0, radial velocity v0, azimuth angle θ0 and height h0 from the ground of the real detection point T relative to the radar, a plane rectangular coordinate system XOY is established in the plane perpendicular to the ground, the projection point R0 of the radar R on the ground is taken as the origin O of the plane rectangular coordinate system, the projection point of the real detection point T on the ground is denoted as T0, and the projection height is h R , then the X axis points from R0 to T0, and the Y axis points from R0 to R; therefore, the position coordinates of the radar R are (0, h R ), the position coordinates of the real detection point T are (r0, h0), and the position coordinates of the reflection point G of the radar signal on the ground are (r0h R / (h0+h R , 0); within a short time Δt of the detection target motion, it can be approximately considered that the motion state of the detection target remains unchanged, that is, the real detection point performs uniform linear motion, and the coordinates of the position T' reached are (r0-v0Δt, h0), and the positions reached by T1, T2 and T3 are denoted as T'1, T'2 and T'3.

[0084] For the first type of multi-path detection point T1, since T1 and T, T'1 and T' are symmetrical about the X axis, the distance r1 of T1 relative to the radar is |RT1| = |RG| + |TG|, the radial velocity v1 of T1 is equal to the radial velocity v0 of the real detection point T, and the azimuth angle θ1 of T1 is determined according to the distance r1.

[0085] For the second type of multi-path detection point T2, T2 is on the extension line of RG and |RT2| = 1 / 2(|RG| + |TG| + |RT|), the position parameters and the azimuth angle θ2 of T2' are calculated according to the position parameters of T2, then the distance r2 of T2 is |RT2|, and the radial velocity v2 of T2 is v2 = v0·|T2T'2| / |TT'|.

[0086] For the third type of multi-path detection point, T3 is on the extension line of RT and |RT3| = 1 / 2(|RG| + |TG| + |RT|), the position parameters and the azimuth angle θ3 of T3' are calculated according to the position parameters of T3, then the distance r3 of T3 is |RT3|, and the radial velocity v3 of T3 is v3 = v0·|T3T'3| / |TT'|.

[0087] Step 6, the radar echo signal matrix corresponding to the real detection point and the three types of multi-path detection points is determined, so as to simulate and generate the radar echo signal.

[0088] In the radar detection process, each detection point Q will generate an echo signal matrix S q , and the three dimensions of the echo signal matrix S q are defined as the receiving element dimension, the slow time dimension and the fast time dimension in turn; the simulation time length is T a , and the number of elements of the radar receiving antenna is Ne , the array element spacing is d, the light speed is c, and the signal carrier frequency is f c , the signal time width is T r , the signal bandwidth is B, and the signal sampling frequency is f s , the slow time number of the received signal is N a =T a / T r , the intra-pulse signal sampling point number N p =T r f s .

[0089] According to the real detection points obtained in step 4 and the three types of multipath detection points obtained in step 5, the radar echo signal is determined;

[0090] Let the detection point Q represent a real detection point or a certain multipath detection point, then the distance of the detection point Q relative to the radar is r, the radial velocity is v, and the azimuth angle is θ; for the m q th array element reception, the n q th echo pulse, and the i q th signal sampling point, the expression of the signal time delay τ is:

[0091]

[0092] Where, the fast time t=(i q -1) / f s , then the expression of any element S q (m q ,n q ,i q ) in the echo signal matrix is:

[0093]

[0094] In the above formula, j is the imaginary unit.

[0095] According to formulas (7) and (8), the echo signal matrix S q corresponding to all real detection points and corresponding three types of multipath detection points is obtained; the echo signal matrix S q of all real detection points and corresponding three types of multipath detection points in the radar beam illumination range is accumulated, and the frequency-modulated continuous wave radar echo signal S of the detection scene is obtained, that is, S=∑S q .

[0096] Embodiment:

[0097] In an embodiment of the present application, in the detection scene as shown in FIG. Figure 2 , it is assumed that there is a frequency-modulated continuous wave radar with a height h R of 5m from the ground in the detection scene, and NT = 3 detection targets. To generate radar point cloud and echo data for this detection scenario, a reference coordinate system is established using the ground as the xoy plane. The radar's position (x0, y0) in the reference coordinate system is (100m, 200m), and its velocity (v) is... x0 ,v y0 Let the velocity be (0 m / s, 0 m / s), and the normal of the radar antenna array be rotated clockwise by an angle α of 0.1 rad relative to the y-axis. Let the velocity of the i-th target be (v... xi ,v yi ), where i = 1, 2, ..., N T The targets have velocities of (0 m / s, 0 m / s), (-5 m / s, -5 m / s), and (3 m / s, 6 m / s). Different types of targets are modeled as distinct polygons defined by multiple vertices. The position of the j-th vertex of the i-th target is (x...). ij ,y ij ), where j = 1, 2, ..., N Pi The center coordinates of the three targets in the reference coordinate system are (115m, 230m), (105m, 225m), and (85m, 210m). The third target is not within the radar beam coverage area, and all target polygons are rectangles with four vertices, and all vertices are 6m above the ground.

[0098] The distance resolution r set in this embodiment res =0.15m, angular resolution θ res =1.5°, the resulting detection points distributed along the target edge are as follows Figure 4 As shown, the ideal point cloud simulation results are as follows: Figure 5 As shown; finally, the echo components corresponding to all real detection points and multipath detection points within the radar beam illumination range are summed to obtain the frequency-modulated continuous wave radar echo signal of this detection scenario. Constant false alarm rate (CFAR) detection is then performed on the range Doppler characteristic map of the echo signal, as shown... Figure 6 As shown, the distance and velocity characteristics of the two targets within the radar beam range are consistent with the scenario settings.

[0099] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for radar point cloud and echo simulation based on spatial features, characterized in that, The application relates to a radar detection scene modeling method and device. The application comprises the following steps: modeling a detection target in a frequency-modulated continuous wave radar detection scene in a reference coordinate system, and modeling the detection target as a polygon composed of multiple vertices; determining position parameters and velocity parameters of the radar, the detection target and the vertices in the reference coordinate system; constructing a radar rectangular coordinate system and a radar polar coordinate system, determining the distance and azimuth angle of all the vertices of each detection target in the radar polar coordinate system by using the position parameters and velocity parameters of the radar, the detection target and the vertices in the reference coordinate system; for each detection target, sorting all the vertices, screening out boundary vertices according to the azimuth angle of the vertices, determining a vertex set as a line-of-sight vertex based on the distance between the vertex sets formed by the boundary vertices and the radar, and discretely processing the target edges between adjacent line-of-sight vertices into a series of detection points, and then determining the position parameters, radial velocity and azimuth angle of the detection points relative to the radar; for each group of adjacent detection points on each detection target, taking the area between the detection points as a shielding interval, and sequentially calculating whether each detection point of other targets is shielded by the shielding interval and is outside the line-of-sight range, so as to screen out all the detection points in the line-of-sight range, and the detection points constitute an ideal point cloud of the radar detection scene, and the detection points are recorded as real detection points; based on the multipath effect of the radar signal in the detection scene, three types of multipath detection points corresponding to each real detection point in the ideal point cloud are obtained, and the position parameters, radial velocity and azimuth angle of each type of multipath detection point are determined; 2. The method of claim 1, wherein, determining the radar echo signal matrix corresponding to the real detection points and the three types of multipath detection points, so as to simulate and generate the radar echo signal.

3. The method of claim 1, wherein, The reference coordinate system takes the ground as an xoy plane, the radar rectangular coordinate system takes the position of the radar as an origin o', and the normal of the radar antenna array is a y' axis; the radar polar coordinate system takes o' as a pole, a y' axis as a polar axis, and clockwise as a positive direction of a polar angle; according to the conversion relationship between the reference coordinate system and the radar rectangular coordinate system and the corresponding relationship between the radar rectangular coordinate system and the radar polar coordinate system, the distance and azimuth angle of all the vertices of each detection target in the radar polar coordinate system are obtained. Firstly, all vertices of each detected target are arranged in clockwise order in radar polar coordinate system, two vertices corresponding to maximum azimuth angle and minimum azimuth angle are selected as demarcation vertices, vertices between demarcation vertices and vertices outside demarcation vertices constitute two vertex sets respectively; average value of distances of all vertices in each vertex set from radar r ij is calculated, then vertex set containing vertex with smaller distance average value is the vertex of visual distance, target edge between adjacent vertices of visual distance is the edge of visual distance which can be detected by radar, and is taken as the object of discrete detection points; Secondly, according to the preset distance resolution r res and angle resolution θ res Discretize the target edge between the adjacent visual range vertexes on each detection target into detection points X k ; Finally, based on the detection point X k azimuth angle θ k And the velocity of the target in the radar's Cartesian coordinate system, determine the component of the velocity of the detection point relative to the radar along the line connecting the two, i.e., the radial velocity v. k Define the radial velocity of the detection point as positive when it approaches the radar, and obtain the detection point X on the edge of the target. k The radial velocity; thus determining the radial velocity of all probe points X. k Relative to the radar distance r k Radial velocity v k Azimuth θ k and height h above the ground k .

4. The method of claim 3, wherein, The distance resolution r res and angle resolution θ res discretize the target edge between adjacent visual range vertexes on each detection target into detection points X k , comprising: For any one group of adjacent range vertexes of a detection target, let the distance of one vertex be r m , the azimuth be θ m , and the height be h m , and the distance of another vertex be r n , the azimuth be θ n , and the height be h n , then the distance range of the target edge between them is Δr = |r m -r n |, the angle range is Δθ = |θ m -θ n |, and the relationship between the distance r k and the azimuth θ k of the detection point X k on the target edge relative to the radar can be expressed as: The method for discretely processing the target edges into detection points can be divided into two types: When |Δr / r res |>|Δθ / θ res At that time, the detection point X on the edge of the target k The number of N1 = Δr / r res +1; when |Δr / r res |≤|Δθ / θ res At that time, the detection point X i The number of them is N2 = Δθ / θ res +1; Detection point X k distance r k =k·r res +min{r m ,r n }, at a height of h above the ground k =k·|h m -h n | / (N1-1)+min{h m ,h n }, where k represents the k-th detection point, k = 0, 1, ..., (N1-1), and the azimuth angle θ of the detection point is calculated according to the above formula. k .

5. The method of claim 1, wherein, for each group of adjacent detection points on each detection target, taking the area between the detection points as a shielding interval, and sequentially calculating whether each detection point of other targets is shielded by the shielding interval and is outside the line-of-sight range, comprising: Among all the detection points discrete on the target edge between any one group of adjacent visual distance vertexes on the detection target, A and B are two adjacent detection points, the area between the two detection points A and B is taken as the shielding interval AB; the distances of A, B and P relative to the radar are respectively r a 、 b 、 p The azimuth angles are respectively θ a 、 b 、 p The height values are respectively h a 、 b 、 p The condition that the detection point P is shielded by the shielding interval AB is: condition one, in the angle domain, P is located in the angle range of AB, that is: (θ a -θ p )(θ b -θ p )≤0 Condition two, in the angle-distance domain, P is located "behind" AB, draw PP0⊥AB through P, and the foot point is recorded as P0, then the condition is equivalent to the distance value of vector is greater than or equal to the distance value of vector , wherein and The expression is: Condition three, in the distance-height domain, the slope coefficient k of P p is less than or equal to the slope coefficient k of the occlusion interval AB ab , that is, k p ≤k ab ; since the distance between adjacent detection points is extremely small, the slope coefficient of the occlusion interval is approximately the average of the slope coefficients of adjacent detection points, then k p and k ab The expression is: if conditions one to three are met at the same time, P is shielded by AB and is outside the line-of-sight range.

6. The method of claim 1, wherein, According to whether the transmitted and scattered radar signals are reflected by the ground, the multipath signal propagation paths are divided into three categories: "radar-ground-target-ground-radar", "radar-target-ground-radar", and "radar-ground-target-radar"; therefore, each real detection point T in the ideal point cloud corresponds to three types of multipath detection points, i.e., the first type of multipath detection point T1, the second type of multipath detection point T2, and the third type of multipath detection point T3; The distance r0, radial velocity v0, azimuth angle θ0 and height h0 from the ground of the real detection point T relative to the radar, the projection point R0 of the radar R on the ground is taken as the origin O of the plane rectangular coordinate system, the projection point of the real detection point T on the ground is taken as T0, and the projection height is h R Then the X axis points from R0 to T0, and the Y axis points from R0 to R; therefore, the position coordinates of the radar R are (0, h R ), the position coordinates of the real detection point T are (r0, h0), and the position coordinates of the reflection point G of the radar signal on the ground are (r0h R / (h0+h R ), 0); within a short time Δt of the detection target motion, it can be approximately considered that the motion state of the detection target remains unchanged, that is, the real detection point moves at a constant speed in a straight line, and the coordinates of the position T' reached are (r0-v0Δt, h0), and the positions reached by T1, T2 and T3 are taken as T1', T2' and T3'; For the first type of multipath detection point T1, since T1 and T, T1' and T' are symmetric about the X-axis, the distance r1 of T1 relative to the radar is |RT1| = |RG| + |TG|, the radial velocity v1 of T1 is equal to the radial velocity v0 of the real detection point T, and the azimuth angle θ1 of T1 is determined according to the distance r1; For the second type of multipath detection point T2, T2 is on the extension line of RG and |RT2| = 1 / 2(|RG| + |TG| + |RT|), the position parameters of T2' and the azimuth angle θ2 can be obtained according to the position parameters of T2, then the distance r2 of T2 is |RT2|, and the radial velocity v2 is v2 = v0·|T2T2'| / |TT'|; For the third type of multipath detection point, T3 is on the extension line of RT and |RT3| = 1 / 2(|RG| + |TG| + |RT|), the position parameters of T3' and the azimuth angle θ3 can be obtained according to the position parameters of T3, then the distance r3 of T3 is |RT3|, and the radial velocity v3 is v3 = v0·|T3T3'| / |TT'|.

7. The method of claim 1, wherein, The distance of the detection point Q relative to the radar is r, the radial velocity is v, and the azimuth angle is θ. For the mth q array element, the nth q echo pulse, and the ith q signal sampling point, the expression of the signal time delay τ is: Wherein, the speed of light is c, the element interval is d, the signal time width is T r , the signal sampling frequency is f s , the fast time t=(i q -1) / f s , and the expression of any element S q (m q ,n q ,i q ) in the echo signal matrix is as follows: In the above equation, the imaginary unit is j, the signal bandwidth is B, and the signal carrier frequency is f c ; After obtaining all the real probe points and the corresponding echo signal matrix S of the three types of multipath probe points q After obtaining all the real probe points and the corresponding echo signal matrix S of the three types of multipath probe points q After obtaining all the real probe points and the corresponding echo signal matrix S of the three types of multipath probe points 8.A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, The processor executes the computer program to implement the radar point cloud and echo simulation method based on spatial features according to any one of claims 1-7.

9. A computer readable storage medium having stored therein a computer program; characterized in that, The computer program is executed by the processor to implement the radar point cloud and echo simulation method based on spatial features according to any one of claims 1-7.

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