Radar calibration and radar true north calibration method

Abstract

The present invention discloses a radar calibration and true north calibration method. The method involves obtaining the rectangular coordinates of the sphere center of a first reference point and a second reference point on the roadside where the radar is installed. Based on the rectangular coordinates of the sphere centers of the two reference points and information such as the distance and angle between the radar surface target point and the reference points, the longitude and latitude of the radar center are calculated. Geometric operations are then performed on the longitude and latitude information of the radar surface target point to obtain the true north deflection angle of the radar normal. This method eliminates the need for road closures during the calibration process, solves the problem of complex radar calibration operations in the prior art, and improves the efficiency and safety of calibration work.

Description

Technical Field

[0001] The present invention belongs to the field of radar technology, and in particular relates to a radar calibration and a radar true north calibration method. Background Art

[0002] The rapid development of the transportation industry and the increasingly complex road traffic environment are driving my country's demand for intelligent traffic management systems that are more intelligent, comprehensive, accurate, and real-time. Meeting these requirements requires reliable, real-time, and accurate detection data, including multimodal data provided by big data, geomagnetic sensors, video, and radar. The application and development of radar technology in the field of intelligent transportation has greatly facilitated solutions to various issues related to intelligent transportation safety management and traffic parameter detection.

[0003] In recent years, vehicle-road collaborative perception technology has become a key research topic in intelligent transportation. It provides accurate road condition information to both traffic participants and traffic managers, reducing the occurrence of traffic accidents. Millimeter-wave radar is a key sensing method for roadside perception systems. To accurately determine the location of traffic participants, the north deflection angle between the radar position and the radar normal must be precisely measured.

[0004] Traditional calibration methods require road closures and data collection on urban highways or at intersections. This method is complex, inefficient, and dangerous. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a radar calibration and radar true north calibration method. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] A radar calibration and radar true north calibration method, comprising:

[0007] Step 1: Establish a spherical center rectangular coordinate system with the center of the earth's ellipsoid as the origin, the intersection of the starting meridian plane and the equator as the X-axis, the short axis of the ellipsoid as the Z-axis, and the direction perpendicular to the X-axis on the equatorial plane as the Y-axis;

[0008] Step 2: Obtain the coordinates of a first reference point A and a second reference point B on the roadside where the radar is installed in the spherical center rectangular coordinate system, and calculate the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis;

[0009] Step 3: Perform geometric vector operations based on the positional relationship between the first reference point A, the second reference point B, and the radar center point C, and the angle calculated in step 2, to obtain the coordinates of the radar center point C in the spherical center rectangular coordinate system, and convert them into GPS coordinates to achieve radar calibration;

[0010] Step 4: Based on the positional relationship between the first reference point A, the second reference point B, and the first target point D on the radar surface, and the angle calculated in step 2, a geometric vector operation is performed to obtain the coordinates of the first target point D in the spherical center rectangular coordinate system, and the coordinates are converted into GPS coordinates;

[0011] Step 5: Based on the positional relationship between the first reference point A, the second reference point B, and the second target point E on the radar surface, and the angle calculated in step 2, a geometric vector operation is performed to obtain the coordinates of the second target point E in the spherical center rectangular coordinate system, and the coordinates are converted into GPS coordinates;

[0012] Step 6: Use the GPS coordinates of the first target point D obtained in step 4 and the GPS coordinates of the second target point E obtained in step 5 to calculate the angle between the vector direction connecting the two target points and the true north direction, and further convert it into the true north deflection angle of the radar normal to achieve radar true north calibration.

[0013] In one embodiment of the present invention, in step 2, the angle between the direction of the vector connecting the first reference point A and the second reference point B and the X-axis is calculated according to the following formula:

[0014] angle=arccos(D AB (1))×180 / PI

[0015] Where angle represents the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis, PI represents a constant, and D AB Is to calculate the intermediate value, its expression is:

[0016] D AB =[X B -X A ,Y B -Y A ,Z B -Z A ]

[0017] D AB =D AB / |D AB |

[0018] (X A ,Y A ,Z A ) and (X B ,Y B ,Z B ) represent the coordinates of the first reference point A and the second reference point B in the spherical center rectangular coordinate system.

[0019] In one embodiment of the present invention, step 3 includes:

[0020] 31) Obtain the horizontal angle α between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the radar center point C BC , the slant distance S between the first reference point A and the radar center point C, and the elevation angle β between the first reference point A and the radar center point C;

[0021] 32) According to the angle calculated in step 2, the horizontal angle α obtained in step 31) BC , slant range S, and elevation angle β to calculate the coordinates (X) of the radar center point C in the sphere center rectangular coordinate system C ,Y C ,Z C );

[0022] 33) The coordinates (X C ,Y C ,Z C ) is converted to GPS coordinates (B C ,L C ,H C ).

[0023] In one embodiment of the present invention, step 32) includes:

[0024] 32a) Calculate the angle α between the vector direction connecting the radar center point C and the origin and the X axis C , the calculation formula is:

[0025] α C =angle+α BC

[0026] 32b) Calculate the coordinates of the radar center point C in the spherical center rectangular coordinate system using the following formula:

[0027] X C =X A +S×cosβ×cosα C

[0028] Y C =Y A +S×cosβ×sinα C

[0029] Z C =Z A +S×sinβ

[0030] Among them, X C Y is the horizontal coordinate of the radar center point C in the spherical center rectangular coordinate system, C is the vertical coordinate of the radar center point C in the spherical center rectangular coordinate system, Z CIt is the vertical coordinate of the radar center C in the spherical center rectangular coordinate system.

[0031] In one embodiment of the present invention, step 4 includes:

[0032] 41) Obtain the horizontal angle α between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the first target point D on the radar surface BD , the slant distance S_1 between the first reference point A and the first target point D, and the elevation angle γ between the first reference point A and the first target point D;

[0033] 42) According to the angle calculated in step 2, the horizontal angle α obtained in step 41) BD , slant distance S_1, and elevation angle γ to calculate the coordinates (X D ,Y D ,Z D );

[0034] 43) The coordinates (X D ,Y D ,Z D ) is converted to GPS coordinates (B D ,L D ,H D ).

[0035] In one embodiment of the present invention, step 42) includes:

[0036] 42a) Calculate the angle α between the vector direction connecting the first target point D and the origin and the X axis D , the calculation formula is:

[0037] α D =angle+α BD

[0038] 42b) Calculate the coordinates of the first target point D in the sphere center rectangular coordinate system using the following formula:

[0039] X D =X A +S_1×cosγ×cosα D

[0040] Y D =Y A +S_1×cosγ×sinα D

[0041] Z D =Z A +S_1×sinγ

[0042] Among them, X D is the horizontal coordinate of the first target point D in the rectangular coordinate system of the sphere center, Y D is the ordinate of the first target point D in the rectangular coordinate system at the center of the sphere, Z D It is the vertical coordinate of the first target point D in the rectangular coordinate system of the sphere center.

[0043] In one embodiment of the present invention, step 5 includes:

[0044] 51) Obtain the horizontal angle α between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the second target point E on the radar surface BE , the slant distance S_2 between the first reference point A and the second target point E, and the elevation angle θ between the first reference point A and the second target point E;

[0045] 52) According to the angle angle calculated in step 2 and the horizontal angle α obtained in step 51) BE , slant distance S_2, and elevation angle θ to calculate the coordinates (X) of the second target point E in the sphere center rectangular coordinate system. E ,Y E ,Z E );

[0046] 53) The coordinates (X E ,Y E ,Z E ) is converted to GPS coordinates (B E ,L E ,H E ).

[0047] In one embodiment of the present invention, step 52) includes:

[0048] 52a) Calculate the angle α between the vector direction connecting the second target point E and the origin and the X axis E , the calculation formula is:

[0049] α E =angle+α BE

[0050] 52b) Calculate the coordinates of the second target point E in the sphere center rectangular coordinate system using the following formula:

[0051] X E =X A +S_2×cosθ×cosα E

[0052] Y E =Y A +S_2×cosθ×sinαE

[0053] Z E =Z A +S_2×sinθ

[0054] Among them, X E is the horizontal coordinate of the second target point E in the rectangular coordinate system of the sphere center, Y E is the ordinate of the second target point E in the rectangular coordinate system at the center of the sphere, Z E It is the vertical coordinate of the second target point E in the rectangular coordinate system of the sphere center.

[0055] In one embodiment of the present invention, step 6 includes:

[0056] 61) Using the GPS coordinates of the first target point D obtained in step 4 and the GPS coordinates of the second target point E obtained in step 5, calculate the angle ANGLE between the vector direction connecting the two target points and the true north direction. The calculation formula is:

[0057]

[0058] in,

[0059] ang=arctan((L E -L D )×cos(B E ) / (B E -B D ))

[0060] d_Lon=L E -L D

[0061] d_Lat=B E -B D

[0062] Among them, B D , L D Denote the latitude and longitude of the first target point D, B E , L E represent the latitude and longitude of the second target point E respectively;

[0063] d_Lon represents the longitude difference between the first target point D and the second target point E, and d_Lat represents the latitude difference between the first target point D and the second target point E;

[0064] 62) Based on the direction of the radar normal, the angle ANGLE obtained in step 1 is processed, and the formula for calculating the true north deflection angle of the radar normal is:

[0065] ang_normal = ANGLE ± 90°

[0066] Where ang_normal represents the north deflection angle of the radar normal.

[0067] Beneficial effects of the present invention:

[0068] The radar calibration and radar true north calibration methods provided by the present invention utilize the accuracy of GPS data to convert the rectangular coordinate position of the reference point sphere center on the roadside where the radar is installed into the position information of the radar surface target point, thereby performing radar calibration; at the same time, by performing geometric vector operations on the GPS data of the radar surface target point, the radar true north calibration is performed to obtain accurate latitude and longitude information of traffic participants, thereby providing traffic managers with more accurate road traffic conditions; this method does not require road closures during the calibration process, solves the problem of complex radar calibration operations in the prior art, and improves the efficiency and safety of the calibration work.

[0069] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is a flow chart of a radar calibration and radar true north calibration method provided by an embodiment of the present invention;

[0071] Figure 2 Schematic diagram of a radar calibration method according to an embodiment of the present invention;

[0072] Figure 3 Schematic diagram of the radar normal north deflection angle provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0073] The present invention will be further described in detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0074] Example 1

[0075] See Figure 1 , Figure 1 The following is a flow chart of a radar calibration and radar true north calibration method provided by an embodiment of the present invention, which includes:

[0076] Step 1: Establish a spherical center rectangular coordinate system with the center of the Earth's ellipsoid as the origin, the intersection of the starting meridian plane and the equator as the X-axis, the short axis of the ellipsoid as the Z-axis, and the direction perpendicular to the X-axis on the equatorial plane as the Y-axis.

[0077] Specifically, different spherical center rectangular coordinate systems have different long and short radii and flattenings. Therefore, when establishing a spherical center rectangular coordinate system, it is necessary to consider the topography and choose a suitable spherical center rectangular coordinate system so that the spherical center rectangular coordinates can be accurately converted into GPS coordinates (also known as latitude and longitude coordinates) later.

[0078] For example, the commonly used CGCS2000 coordinate system is suitable for my country's topography. The converted latitude and longitude data format is (23.326807373055°N, 113.545784232222°E), where 23.326807373055°N is latitude, 113.545784232222°E is longitude, and N and E are north latitude and east longitude, respectively.

[0079] For the constructed spherical rectangular coordinate system, the Z axis points to the North Pole of the Earth.

[0080] Step 2: Obtain the coordinates of the first reference point A and the second reference point B on the roadside where the radar is installed in the rectangular coordinate system of the sphere center, and calculate the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis.

[0081] In this embodiment, the first reference point A and the second reference point B are selected based on the condition that the GPS observation conditions on the roadside where the radar is installed are good.

[0082] Specifically, the rectangular coordinates of the sphere center of the first reference point A and the second reference point B are defined as (X A ,Y A ,Z A )、(X B ,Y B ,Z B ), which can be obtained through RTK, then the angle between the vector direction connecting A and B and the X axis can be calculated as follows:

[0083] angle=arccos(D AB (1))×180 / PI

[0084] Where angle represents the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis, PI represents a constant, and D AB Is to calculate the intermediate value, its expression is:

[0085] D AB =[X B -X A ,Y B -Y A ,Z B -Z A ]

[0086] D AB =D AB / |D AB |

[0087] Step 3: Based on the positional relationship between the first reference point A, the second reference point B and the radar center point C and the angle calculated in step 2, perform geometric vector operations to obtain the coordinates of the radar center point C in the spherical center rectangular coordinate system, and convert them into GPS coordinates to achieve radar calibration.

[0088] See Figure 2 , Figure 2 Schematic diagram of a radar calibration method according to an embodiment of the present invention, wherein A is the first reference point, B is the second reference point, and C is the radar geometric center.

[0089] Specifically, step 3 includes:

[0090] 31) Obtain the horizontal angle α between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the radar center point C BC , the slant distance S between the first reference point A and the radar center point C, and the elevation angle β between the first reference point A and the radar center point C.

[0091] Specifically, in this embodiment, the above-mentioned distance and angle can be accurately measured using instruments such as a total station and theodolite.

[0092] It should be noted that the horizontal angle α BC The positive and negative judgment method is: when measuring the horizontal angle with the first reference point A as the center, when measuring from the radar center C to the second reference point B, the horizontal angle measured by rotating the measuring instrument clockwise is positive, and the horizontal angle measured by rotating counterclockwise is negative.

[0093] 32) According to the angle calculated in step 2, the horizontal angle α obtained in step 31) BC , slant range S, and elevation angle β to calculate the coordinates (X) of the radar center point C in the sphere center rectangular coordinate system C ,Y C ,Z C ).

[0094] 32a) Calculate the angle α between the vector direction connecting the radar center point C and the origin and the X axis C , the calculation formula is:

[0095] α C =angle+α BC

[0096] 32b) Calculate the coordinates of the radar center point C in the spherical center rectangular coordinate system using the following formula:

[0097] X C =X A +S×cosβ×cosα C

[0098] Y C =Y A +S×cosβ×sinα C

[0099] Z C =Z A +S×sinβ

[0100] Among them, X C Y is the horizontal coordinate of the radar center point C in the spherical center rectangular coordinate system, C is the vertical coordinate of the radar center point C in the spherical center rectangular coordinate system, Z C It is the vertical coordinate of the radar center C in the spherical center rectangular coordinate system.

[0101] 33) The coordinates (X C ,Y C ,Z C ) is converted to GPS coordinates (B C ,L C ,H C ).

[0102] Specifically, the coordinates (X C ,Y C ,Z C ) is directly converted to GPS coordinates (B C ,L C ,H C ), where (B C ,L C ,H C ) represent the latitude, longitude and altitude of the radar center point C respectively.

[0103] Step 4: Based on the positional relationship between the first reference point A, the second reference point B and the first target point D on the radar surface and the angle calculated in step 2, perform geometric vector operations to obtain the coordinates of the first target point D in the sphere center rectangular coordinate system and convert them into GPS coordinates.

[0104] 41) Obtain the horizontal angle α between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the first target point D on the radar surface BD , the slant distance S_1 between the first reference point A and the first target point D, and the elevation angle γ between the first reference point A and the first target point D.

[0105] Specifically, in this embodiment, the above-mentioned distance and angle can be accurately measured using instruments such as a total station and theodolite.

[0106] It should be noted that the horizontal angle α BD The positive and negative judgment method is: when measuring the horizontal angle with the first reference point A as the center, when measuring from the first target point D to the second reference point B, the horizontal angle measured by rotating the measuring instrument clockwise is positive, and the horizontal angle measured by rotating it counterclockwise is negative.

[0107] 42) According to the angle calculated in step 2, the horizontal angle α obtained in step 41) BD , slant distance S_1, and elevation angle γ to calculate the coordinates (X D ,Y D ,Z D ).

[0108] 42a) Calculate the angle α between the vector direction connecting the first target point D and the origin and the X axis D , the calculation formula is:

[0109] α D =angle+α BD

[0110] 42b) Calculate the coordinates of the first target point D in the sphere center rectangular coordinate system using the following formula:

[0111] X D =X A +S_1×cosγ×cosα D

[0112] Y D =Y A +S_1×cosγ×sinα D

[0113] Z D =Z A +S_1×sinγ

[0114] Among them, X D is the horizontal coordinate of the first target point D in the rectangular coordinate system of the sphere center, Y D is the ordinate of the first target point D in the rectangular coordinate system at the center of the sphere, Z D It is the vertical coordinate of the first target point D in the rectangular coordinate system of the sphere center.

[0115] 43) The coordinates (X D ,Y D ,Z D ) is converted to GPS coordinates (B D ,L D ,H D ).

[0116] Specifically, the coordinates (X D ,Y D ,Z D ) is directly converted to GPS coordinates (B D ,L D ,H D ), where (B D ,L D ,H D ) represent the latitude, longitude and altitude of the first target point D respectively.

[0117] Step 5: Based on the positional relationship between the first reference point A, the second reference point B and the second target point E on the radar surface and the angle calculated in step 2, perform geometric vector operations to obtain the coordinates of the second target point E in the sphere center rectangular coordinate system and convert them into GPS coordinates.

[0118] 51) Obtain the horizontal angle α between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the second target point E on the radar surface BE , the slant distance S_2 between the first reference point A and the second target point E, and the elevation angle θ between the first reference point A and the second target point E.

[0119] Specifically, in this embodiment, the above-mentioned distance and angle can be accurately measured using instruments such as a total station and theodolite.

[0120] It should be noted that the horizontal angle α BE The positive and negative judgment method is: when measuring the horizontal angle with the first reference point A as the center, when measuring from the second target point E to the second reference point B, the horizontal angle measured by rotating the measuring instrument clockwise is positive, and the horizontal angle measured by rotating it counterclockwise is negative.

[0121] 52) According to the angle angle calculated in step 2 and the horizontal angle α obtained in step 51) BE , slant distance S_2, and elevation angle θ to calculate the coordinates (X) of the second target point E in the sphere center rectangular coordinate system. E ,Y E ,Z E ).

[0122] 52a) Calculate the angle α between the vector direction connecting the second target point E and the origin and the X axis E , the calculation formula is:

[0123] α E =angle+α BE

[0124] 52b) Calculate the coordinates of the second target point E in the sphere center rectangular coordinate system using the following formula:

[0125] X E =X A +S_2×cosθ×cosα E

[0126] Y E =Y A +S_2×cosθ×sinα E

[0127] Z E =Z A +S_2×sinθ

[0128] Among them, X E is the horizontal coordinate of the second target point E in the rectangular coordinate system of the sphere center, Y E is the ordinate of the second target point E in the rectangular coordinate system at the center of the sphere, Z E It is the vertical coordinate of the second target point E in the rectangular coordinate system of the sphere center.

[0129] 53) The coordinates (X E ,Y E ,Z E ) is converted to GPS coordinates (B E ,L E ,H E ).

[0130] Specifically, the coordinates (X E ,Y E ,Z E ) is directly converted to GPS coordinates (B E ,L E ,H E ), where (B E ,L E ,H E ) represent the latitude, longitude and elevation of the second target point E respectively.

[0131] Step 6: Use the GPS coordinates of the first target point D obtained in step 4 and the GPS coordinates of the second target point E obtained in step 5 to calculate the angle between the vector direction connecting the two target points and the true north direction, and further convert it into the true north deflection angle of the radar normal to achieve radar true north calibration.

[0132] In this embodiment, triangulation of the longitude and latitude information of the radar surface observation point can accurately and quickly calculate the radar normal deflection angle, as follows:

[0133] 61) Using the GPS coordinates of the first target point D obtained in step 4 and the GPS coordinates of the second target point E obtained in step 5, calculate the angle ANGLE between the vector direction connecting the two target points and the true north direction. The calculation formula is:

[0134]

[0135] in,

[0136] ang=arctan((L E -L D )×cos(B E ) / (B E -B D ))

[0137] d_Lon=L E -L D

[0138] d_Lat=B E -B D

[0139] Among them, B D , L D Denote the latitude and longitude of the first target point D, B E , L E represent the latitude and longitude of the second target point E respectively;

[0140] d_Lon represents the longitude difference between the first target point D and the second target point E, and d_Lat represents the latitude difference between the first target point D and the second target point E;

[0141] 62) Based on the direction of the radar normal, the angle ANGLE obtained in step 1 is processed, and the formula for calculating the true north deflection angle of the radar normal is:

[0142] ang_normal = ANGLE ± 90°

[0143] Among them, ang_normal represents the north deflection angle of the radar normal,

[0144] Furthermore, the plus and minus signs in the calculation formula of the true north deflection angle of the radar normal need to be determined according to the direction of the radar normal. Knowing the angle ANGLE between the radar surface and the true north direction (the clockwise angle with the true north direction is positive), the position of the radar in the station center coordinate system is as follows: Figure 3 As shown in the figure, if the normal line of the radar is facing southeast, the north deflection angle of the radar normal line is ANGLE+90°. If the normal line of the radar is facing northwest, the north deflection angle of the radar normal line is ANGLE-90°.

[0145] The radar calibration and radar true north calibration methods provided by the present invention utilize the accuracy of GPS data to convert the rectangular coordinate position of the reference point sphere center on the roadside where the radar is installed into the position information of the radar surface target point, thereby performing radar calibration; at the same time, by performing geometric vector operations on the GPS data of the radar surface target point, the radar true north calibration is performed to obtain accurate latitude and longitude information of traffic participants, thereby providing traffic managers with more accurate road traffic conditions; this method does not require road closures during the calibration process, solves the problem of complex radar calibration operations in the prior art, and improves the efficiency and safety of the calibration work.

[0146] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A radar calibration and radar true north calibration method, characterized in that: include: Step 1: Establish a spherical center rectangular coordinate system with the center of the earth's ellipsoid as the origin, the intersection of the starting meridian plane and the equator as the X-axis, the short axis of the ellipsoid as the Z-axis, and the direction perpendicular to the X-axis on the equatorial plane as the Y-axis; Step 2: Obtain the coordinates of a first reference point A and a second reference point B on the roadside where the radar is installed in the spherical center rectangular coordinate system, and calculate the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis; Step 3: Perform geometric vector operations based on the positional relationship between the first reference point A, the second reference point B, and the radar center point C, and the angle calculated in step 2, to obtain the coordinates of the radar center point C in the spherical center rectangular coordinate system, and convert them into GPS coordinates to achieve radar calibration; Step 4: Based on the positional relationship between the first reference point A, the second reference point B, and the first target point D on the radar surface, and the angle calculated in step 2, a geometric vector operation is performed to obtain the coordinates of the first target point D in the spherical center rectangular coordinate system, and the coordinates are converted into GPS coordinates; Step 5: Based on the positional relationship between the first reference point A, the second reference point B, and the second target point E on the radar surface, and the angle calculated in step 2, a geometric vector operation is performed to obtain the coordinates of the second target point E in the spherical center rectangular coordinate system, and the coordinates are converted into GPS coordinates; Step 6: Use the GPS coordinates of the first target point D obtained in step 4 and the GPS coordinates of the second target point E obtained in step 5 to calculate the angle between the vector direction connecting the two target points and the true north direction, and further convert it into the true north deflection angle of the radar normal to achieve radar true north calibration; Wherein, step 6 includes: 61) Using the GPS coordinates of the first target point D obtained in step 4 and the GPS coordinates of the second target point E obtained in step 5, calculate the angle between the vector direction connecting the two target points and the true north direction. , the calculation formula is: in, in, Respectively represent the latitude and longitude of the first target point D, represent the latitude and longitude of the second target point E respectively; represents the longitude difference between the first target point D and the second target point E, Indicates the latitude difference between the first target point D and the second target point E; 62) According to the direction of the radar normal, the angle obtained in step 1 After processing, the calculation formula for the true north deflection angle of the radar normal is: in, Indicates the north deflection angle of the radar normal.

2. The radar calibration and radar true north calibration method according to claim 1, characterized in that: In step 2, the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis is calculated according to the following formula: in, Indicates the angle between the vector direction connecting the first reference point A and the second reference point B and the X-axis. PI Represents a constant, Is to calculate the intermediate value, its expression is: and They respectively represent the coordinates of the first reference point A and the second reference point B in the spherical center rectangular coordinate system.

3. The radar calibration and radar true north calibration method according to claim 2, characterized in that: Step 3 includes: 31) Obtain the horizontal angle between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the radar center point C , slant distance S between the first reference point A and the radar center point C, elevation angle between the first reference point A and the radar center point C ; 32) According to the angle calculated in step 2 angle , the horizontal angle obtained in step 31) , slant range S, and elevation angle Calculate the coordinates of the radar center point C in the spherical center rectangular coordinate system ; 33) The coordinates of the radar center point C calculated in step 32) in the spherical center rectangular coordinate system are Convert to GPS coordinates .

4. The radar calibration and radar true north calibration method according to claim 3, characterized in that: Step 32) includes: 32a) Calculate the angle between the vector direction connecting the radar center point C and the origin and the X axis , the calculation formula is: 32b) Calculate the coordinates of the radar center point C in the spherical center rectangular coordinate system using the following formula: in, is the horizontal coordinate of the radar center point C in the spherical center rectangular coordinate system, is the ordinate of the radar center point C in the spherical center rectangular coordinate system, It is the vertical coordinate of the radar center C in the spherical center rectangular coordinate system.

5. The radar calibration and radar true north calibration method according to claim 2, characterized in that: Step 4 includes: 41) Obtain the horizontal angle between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the first target point D on the radar surface , the slope distance between the first reference point A and the first target point D S _1. Elevation angle between the first reference point A and the first target point D ; 42) According to the angle calculated in step 2 angle , the horizontal angle obtained in step 41) , slope distance S _1, and elevation angle Calculate the coordinates of the first target point D in the rectangular coordinate system of the sphere center ; 43) The coordinates of the first target point D calculated in step 42) in the rectangular coordinate system of the sphere center are Convert to GPS coordinates .

6. The radar calibration and radar true north calibration method according to claim 5, characterized in that: Step 42) includes: 42a) Calculate the angle between the vector direction connecting the first target point D and the origin and the X axis , the calculation formula is: 42b) Calculate the coordinates of the first target point D in the sphere center rectangular coordinate system using the following formula: in, is the horizontal coordinate of the first target point D in the rectangular coordinate system of the sphere center, is the ordinate of the first target point D in the rectangular coordinate system at the center of the sphere, It is the vertical coordinate of the first target point D in the rectangular coordinate system of the sphere center.

7. The radar calibration and radar true north calibration method according to claim 1, characterized in that: Step 5 includes: 51) Obtain the horizontal angle between the vector formed by the first reference point A and the second reference point B and the vector formed by the first reference point A and the second target point E on the radar surface , the slope distance between the first reference point A and the second target point E S _2. Elevation angle between the first reference point A and the second target point E ; 52) According to the angle calculated in step 2 angle , the horizontal angle obtained in step 51) , slope distance S _2, and elevation angle Calculate the coordinates of the second target point E in the rectangular coordinate system of the sphere center ; 53) The coordinates of the second target point E calculated in step 52) in the rectangular coordinate system of the sphere center are Convert to GPS coordinates .

8. The radar calibration and radar true north calibration method according to claim 7, characterized in that: Step 52) includes: 52a) Calculate the angle between the vector direction connecting the second target point E and the origin and the X axis , the calculation formula is: 52b) Calculate the coordinates of the second target point E in the sphere center rectangular coordinate system using the following formula: in, is the horizontal coordinate of the second target point E in the rectangular coordinate system of the sphere center, is the ordinate of the second target point E in the rectangular coordinate system at the center of the sphere, It is the vertical coordinate of the second target point E in the rectangular coordinate system of the sphere center.

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