Unmanned aerial vehicle terrain mapping device and method based on laser ranging and self-stabilizing gimbal

Abstract

The invention discloses an unmanned aerial vehicle terrain mapping device and method based on laser ranging and a self-stabilizing pan-tilt platform. The mapping device comprises a multi-rotor unmanned aerial vehicle, an airborne GPS module installed at the top of the multi-rotor unmanned aerial vehicle, a self-stabilizing pan-tilt platform arranged below the multi-rotor unmanned aerial vehicle, and a laser ranging module at the bottom of the self-stabilizing pan-tilt platform and facing vertically downward; the self-stabilizing pan-tilt platform comprises a leveling plate, a servo motor, and a fixed plate, the fixed plate is horizontally installed at the bottom of a frame of the multi-rotor unmanned aerial vehicle, the leveling plate is located below the fixed plate, an inclination sensor is installed on the leveling plate, and an external single-chip microcomputer control module for reading inclination sensor data is also arranged on the self-stabilizing pan-tilt platform; a servo motor is arranged on the fixed plate, and a connecting rod mechanism is controlled to ensure that the leveling plate is in a horizontal working state. The invention utilizes the self-stabilizing pan-tilt platform to eliminate the influence of the dynamic change of the body inclination angle on the measurement accuracy of the laser ranging module when the unmanned aerial vehicle mapping system is operating, so that the terrain mapping operation is more convenient, efficient and accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of terrain surveying and mapping, in particular to an unmanned aerial vehicle terrain surveying and mapping device and method based on laser ranging and a self-stabilizing pan-tilt platform. Background Art

[0002] Using multi-rotor drones as carriers, installing laser rangefinders and high-precision global positioning system modules (GPS) for terrain mapping operations, terrain data can be obtained conveniently, quickly and accurately. However, the propellers of multi-rotor drones are fixedly installed on multiple DC motors evenly distributed in the plane of the propeller disk. The lift generated by their high-speed rotation is always perpendicular to the plane of the propeller disk. Therefore, the body of the drone is only in a horizontal state during vertical ascent, vertical descent or fixed-point hovering, and the body flies in an inclined posture in the rest of the stages. For example, when a multi-rotor drone flies in a certain direction at a certain speed, the body of the drone is dynamically adjusted in real time around a certain pitch angle in an inclined posture of "low in front and high in the back"; when the flight speed or flight direction changes, the tilt angle size and direction (pitch angle, roll angle and yaw angle) of the drone body change accordingly, and vice versa. In addition, the UAV mapping system is inevitably affected by various factors such as airflow, crosswind, mechanical vibration, load disturbance, etc. during flight, which aggravates the change of the UAV's inclination angle, and then causes the laser ranging module installed on the UAV to produce inclination deviation, which seriously affects the accuracy of terrain mapping. In order to improve the accuracy of terrain mapping, it is usually adopted to install an attitude sensor on the UAV body and obtain the tilt angle of the UAV after the mapping operation is completed to correct the laser ranging value, such as Figure 3 As shown, d is the measured distance between the multi-rotor drone and the ground point when the multi-rotor drone is tilted at a certain angle, and dcorr is the true distance between the drone and the ground point directly below after using the drone attitude data and correcting it using trigonometric functions. This method can improve the accuracy of terrain mapping to a certain extent in areas with gentle terrain undulations, but using trigonometric functions to correct the laser ranging value in areas with drastic changes in the ground undulations and dense concave and convex blocks will lead to greater system errors. Therefore, there is an urgent need for a device and an advanced method to eliminate the impact of the dynamic flight inclination angle changes of multi-rotor drones on the accuracy of terrain mapping. Summary of the invention

[0003] In order to solve the above problems, the present invention provides an unmanned aerial vehicle terrain surveying and mapping device and method based on laser ranging and a self-stabilizing gimbal, which utilizes the self-stabilizing gimbal to eliminate the influence of the dynamic change of the body inclination angle during the operation of the multi-rotor unmanned aerial vehicle surveying and mapping system on the measurement accuracy of the laser ranging module, thereby making the terrain surveying and mapping operation more convenient, efficient and accurate.

[0004] The present invention is achieved through the following technical solutions:

[0005] The unmanned aerial vehicle terrain mapping device based on laser ranging and self-stabilizing gimbal comprises a multi-rotor unmanned aerial vehicle, an airborne GPS module, a self-stabilizing gimbal, and a laser ranging module. The airborne GPS module is fixedly installed on the top of the multi-rotor unmanned aerial vehicle, the self-stabilizing gimbal is arranged below the multi-rotor unmanned aerial vehicle, and the laser ranging module is fixed at the bottom of the self-stabilizing gimbal and emits and receives ranging laser signals vertically downward.

[0006] The self-stabilizing gimbal comprises a leveling plate, a servo motor, and a fixed plate, wherein the fixed plate is horizontally mounted at the bottom of the frame of the multi-rotor UAV, the leveling plate is located below the fixed plate, an inclination sensor is mounted on the leveling plate, and an external single-chip microcomputer control module for reading inclination sensor data is also arranged on the self-stabilizing gimbal;

[0007] A plurality of servo motors are evenly arranged on the fixed plate, a connecting rod mechanism is arranged between the fixed plate and the leveling plate, the connecting rod mechanism includes a hinge mechanism and a connecting rod, a plurality of servo motors are respectively connected to the connecting rod through rocker arms, and the other end of the connecting rod is connected to the leveling plate through a hinge mechanism.

[0008] Furthermore, the laser ranging module is fixed vertically downward on the bottom of the leveling plate of the self-stabilizing pan / tilt platform.

[0009] Furthermore, the number of the servo motors is 3, namely motor A, motor B, and motor C, and the 3 motors are symmetrically distributed on the fixed disk at an angle of 120°.

[0010] The surveying method of the unmanned aerial vehicle terrain surveying device based on laser ranging and self-stabilizing gimbal mainly includes the following steps:

[0011] Step 1: Set up a GPS base station at any location within 20 kilometers of the survey area, use GPS equipment to obtain the geographical coordinates (longitude, latitude and altitude) of the GPS base station, and use this coordinate as a reference to perform real-time dynamic correction or post-processing correction on the positioning data of the airborne GPS module installed on the top of the multi-rotor drone to obtain the geographical coordinate sequence of the multi-rotor drone terrain surveying system. ,in , , They are the longitude, latitude and altitude of the multi-rotor UAV terrain mapping system;

[0012] Step 2: Set the flight route of the multi-rotor drone so that the ground measurement points have a spatial resolution of no less than 2 meters × 2 meters;

[0013] Step 3: Perform horizontal calibration on the self-stabilizing gimbal of the multi-rotor UAV terrain mapping system at a horizontal position on the ground to ensure that the leveling plate is in a horizontal working state;

[0014] Step 4: The multi-rotor UAV performs terrain mapping according to the pre-planned flight path. During the flight, the UAV's own inclination angle keeps changing. The self-stabilizing gimbal of the multi-rotor UAV terrain mapping system is used for horizontal correction to keep the leveling plate horizontal, so that the laser transmitter and receiver of the laser ranging module are pointed vertically to the ground. At this time, the laser ranging module obtains the distance sequence between the multi-rotor UAV terrain mapping device and the ground point directly below it at a frequency of 10Hz. ;

[0015] Step 5: The geographic coordinate sequence of the multi-rotor UAV terrain mapping device obtained from step 1 Extract the altitude sequence component from , the distance sequence between the multi-rotor UAV terrain mapping device and the ground point directly below it obtained in step 4 , the altitude of the ground point can be obtained

[0016] ;

[0017] in, It is the height difference between the GPS rover antenna installed on the top of the multi-rotor drone and the laser transmitting and receiving lenses of the laser ranging module;

[0018] Step 6: Use the altitude of the ground point obtained in step 5 Replacement of geographic coordinates for multi-rotor drone terrain mapping devices The altitude sequence in , that is, to obtain the geographic coordinate sequence of the ground point ,in , , are the longitude, latitude and altitude of the ground point respectively;

[0019] Step 7: According to the longitude value of the ground point , select the corresponding 3° or 6° band number and obtain the projection plane coordinates according to the Gauss-Krüger projection , using projected plane coordinates A sequence of geographic coordinates that replaces ground points In Coordinates, and finally obtain the projection space coordinates of the ground point ,in , , They are the easting coordinate, northing coordinate and altitude coordinate of the ground point respectively;

[0020] Step 8: Projection space coordinates of the ground point obtained in step 7 , using spatial interpolation algorithm, the altitude coordinates Perform spatial interpolation to generate the required digital terrain model.

[0021] Furthermore, the GPS device in step 1 includes but is not limited to a high-precision real-time kinematic (RTK) GPS device.

[0022] Furthermore, the leveling control method for the self-stabilizing gimbal of the multi-rotor UAV terrain mapping system in step 4 to perform horizontal correction is:

[0023] Step a, set the X-axis and its positive direction along any radial direction in the plane of the fixed disk, rotate 90° counterclockwise from the established positive direction of the X-axis in the plane of the fixed disk to the positive direction of the Y-axis, and determine the positive direction of the Z-axis according to the right-hand rule. During the flight, the inclination angle of the drone body changes continuously, and the external single-chip control module obtains the reading of the inclination sensor installed on the self-stabilizing gimbal leveling plate in real time, that is, the pitch angle change (rotation angle around the Y-axis) of the self-stabilizing gimbal when the drone body tilts. The roll angle change (rotation angle around the X axis) , we get the leveling kinematic model of the self-stabilizing gimbal, which is:

[0024] ;

[0025] ;

[0026] ;

[0027] in is the rotation angle of the output shaft of motor A, is the rotation angle of the output shaft of motor B, is the rotation angle of the output shaft of motor C, is the motor output shaft position proportional constant, It is the original stroke between the fixed plate and the leveling plate when the self-stabilizing gimbal is in the initial horizontal state;

[0028] Step b: Based on the leveling kinematics model of the self-stabilizing gimbal obtained in step a, the external single-chip microcomputer control module uses a PID control algorithm to adjust the rotation angles of the output shafts of the three motors respectively. , , , and then the corresponding rocker arm drives the connecting rod to move, dynamically compensating for the inclination change of the leveling plate, so that the leveling plate remains in a horizontal state.

[0029] Furthermore, the PID control algorithm in step b is:

[0030] ;

[0031] in: is the rotation angle of the motor output shaft; is the proportional control coefficient of the PID control algorithm; is the angle deviation for this adjustment; is the integral control coefficient of the PID control algorithm; is the accumulation of angular deviation (k=1,2,…); is the differential control coefficient of the PID control algorithm; is the angle deviation before adjustment.

[0032] Furthermore, the spatial interpolation algorithm in step eight includes but is not limited to a spline curve spatial interpolation algorithm, a Kriging spatial interpolation algorithm, an inverse distance weighted spatial interpolation algorithm, and an irregular triangulated network spatial interpolation algorithm.

[0033] The beneficial effects of the present invention are:

[0034] (1) Compared with the drone terrain mapping method based on aerial photogrammetry, the drone terrain mapping method based on laser ranging in the present invention can directly obtain point cloud data of the operation area, without the need for cumbersome operation processes such as aerial triangulation and measuring the coordinates of ground control points, and has the advantages of high efficiency and low cost;

[0035] (2) Compared with the embedded integrated three-axis self-stabilizing gimbal of the aerial photography drone, the self-stabilizing gimbal designed by the present invention based on the "servo motor + rocker arm connecting rod mechanism" has the advantages of strong load-bearing capacity, easy disassembly, and the ability to carry multiple sensors at the same time;

[0036] (3) Compared with the traditional method based on laser radar or laser rangefinder, which uses the attitude information of the drone and corrects the mapping results through trigonometric functions, the drone terrain mapping method based on laser ranging and self-stabilizing gimbal in the present invention can eliminate the influence of the inclination angle change of the multi-rotor drone during flight on the terrain mapping accuracy, and can significantly improve the mapping accuracy of areas with steep terrain fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0038] Figure 2 It is a structural schematic diagram of the self-stabilizing pan / tilt platform of the present invention;

[0039] Figure 3 It is a UAV terrain mapping method in the prior art;

[0040] Figure 4 It is a schematic diagram of the height between the multi-rotor UAV terrain mapping device of the present invention and the ground point directly below it;

[0041] Figure numerals: 1. multi-rotor drone, 2. airborne GPS module, 3. self-stabilizing gimbal, 4. laser ranging module, 5. inclination sensor, 6. leveling plate, 7. articulated mechanism, 8. connecting rod, 9. rocker arm, 10. servo motor, 11. fixed plate. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings.

[0043] Example 1

[0044] As shown in the accompanying drawings, the UAV terrain mapping device based on laser ranging and self-stabilizing gimbal comprises a multi-rotor UAV 1, an airborne GPS module 2, a self-stabilizing gimbal 3, and a laser ranging module 4. The airborne GPS module 2 is fixedly mounted on the top of the multi-rotor UAV 1, and the self-stabilizing gimbal 3 is arranged below the multi-rotor UAV 1.

[0045] The self-stabilizing gimbal 3 includes a leveling plate 6, a servo motor 10, and a fixed plate 11. The fixed plate 11 is horizontally mounted at the bottom of the frame of the multi-rotor UAV 1, and the leveling plate 6 is located below the fixed plate 11. The laser ranging module 4 is vertically fixed downward at the bottom of the leveling plate 6 of the self-stabilizing gimbal 3 for transmitting and receiving ranging laser signals; the leveling plate 6 is mounted with a tilt sensor 5, and the self-stabilizing gimbal 3 is also provided with an external single-chip microcomputer control module for reading the tilt sensor data;

[0046] A plurality of servo motors 10 are evenly arranged on the fixed disk 11, and a connecting rod mechanism is arranged between the fixed disk 11 and the leveling disk 6. The connecting rod mechanism includes a hinge mechanism 7 and a connecting rod 8. The plurality of servo motors 10 are connected to the connecting rod 8 through a rocker arm 9, respectively. The other end of the connecting rod 8 is connected to the leveling disk 6 through a hinge mechanism 7. There are three servo motors 10, namely motor A, motor B, and motor C, and the three motors are symmetrically distributed on the fixed disk 11 at an angle of 120°.

[0047] The surveying method of the unmanned aerial vehicle terrain surveying device based on laser ranging and self-stabilizing gimbal mainly includes the following steps:

[0048] Step 1: Set up a GPS base station at any location within 20 kilometers of the survey area, and use high-precision real-time dynamic differential (RTK) GPS equipment to obtain the geographical coordinates (longitude, latitude and altitude) of the GPS base station. Based on this coordinate, perform real-time dynamic correction or post-processing correction on the positioning data of the airborne GPS module 2 installed on the top of the multi-rotor drone to obtain the geographical coordinate sequence of the multi-rotor drone terrain surveying system. ,in , , They are the longitude, latitude and altitude of the multi-rotor UAV terrain mapping system;

[0049] Step 2: Set the flight route of the multi-rotor drone so that the ground measurement points have a spatial resolution of no less than 2 meters × 2 meters;

[0050] Step 3: perform horizontal calibration on the self-stabilizing gimbal of the multi-rotor UAV terrain mapping system at a horizontal position on the ground to ensure that the leveling plate 6 is in a horizontal working state;

[0051] Step 4: The multi-rotor UAV performs terrain mapping according to the pre-planned flight path. During the flight, the inclination angle of the UAV body changes continuously. The self-stabilizing gimbal of the multi-rotor UAV terrain mapping system performs horizontal correction, so that the leveling plate is not affected by the inclination of the multi-rotor UAV body and always maintains a horizontal state. The laser ranging module is fixedly installed on the leveling plate of the self-stabilizing gimbal, so that the laser transmitter and receiver of the laser ranging module 4 are vertically pointed to the ground. At this time, the laser ranging module 4 obtains the distance sequence between the multi-rotor UAV terrain mapping device and the ground point directly below it at a frequency of 10Hz. ,like Figure 4 As shown;

[0052] Furthermore, the leveling control method for the self-stabilizing gimbal of the multi-rotor UAV terrain mapping system in step 4 to perform horizontal correction is:

[0053] Step a, set the X-axis and its positive direction along any radial direction in the plane of the fixed disk 11, rotate 90° counterclockwise from the established positive direction of the X-axis in the plane of the fixed disk 11 to obtain the positive direction of the Y-axis, and determine the positive direction of the Z-axis according to the right-hand rule. During the flight, the inclination angle of the UAV body changes continuously, and the external single-chip microcomputer control module obtains the reading of the inclination sensor 5 installed on the self-stabilizing gimbal leveling plate in real time, that is, the pitch angle change (rotation angle around the Y-axis) of the self-stabilizing gimbal when the UAV body is tilted. The roll angle change (rotation angle around the X axis) , we get the leveling kinematic model of the self-stabilizing gimbal, which is:

[0054] ;

[0055] ;

[0056] ;

[0057] in is the rotation angle of the output shaft of motor A, is the rotation angle of the output shaft of motor B, is the rotation angle of the output shaft of motor C, is the proportional constant of the motor output shaft position, It is the original stroke between the fixed plate and the leveling plate when the self-stabilizing gimbal is in the initial horizontal state;

[0058] Step b: Based on the tilt sensor reading of the leveling plate and the leveling kinematics model of the self-stabilizing gimbal obtained in step a, the external single-chip control module uses the PID control algorithm to adjust the rotation angles of the output shafts of the three motors respectively. , , , and then the corresponding rocker arm drives the connecting rod to move, dynamically compensating for the inclination change of the leveling plate, so that the leveling plate remains in a horizontal state.

[0059] Furthermore, the PID control algorithm in step b is:

[0060] ;

[0061] in: is the rotation angle of the motor output shaft; is the proportional control coefficient of the PID control algorithm; is the angle deviation for this adjustment; is the integral control coefficient of the PID control algorithm; is the accumulation of angular deviation (k=1,2,…); is the differential control coefficient of the PID control algorithm; is the angle deviation before adjustment.

[0062] Step 5: The geographic coordinate sequence of the multi-rotor UAV terrain mapping device obtained from step 1 Extract the altitude sequence component from , the distance sequence between the multi-rotor UAV terrain mapping device and the ground point directly below it obtained in step 4 , the altitude of the ground point can be obtained

[0063] ;

[0064] in, It is the height difference between the GPS rover antenna installed on the top of the multi-rotor drone and the laser transmitting and receiving lenses of the laser ranging module;

[0065] Step 6: Use the altitude of the ground point obtained in step 5 Replacement of geographic coordinates for multi-rotor drone terrain mapping devices The altitude sequence in , that is, to obtain the geographic coordinate sequence of the ground point ,in , , are the longitude, latitude and altitude of the ground point respectively;

[0066] Step 7: According to the longitude value of the ground point , select the corresponding 3° or 6° band number and obtain the projection plane coordinates according to the Gauss-Krüger projection , using projected plane coordinates A sequence of geographic coordinates that replaces ground points In Coordinates, and finally obtain the projection space coordinates of the ground point ,in , , They are the easting coordinate, northing coordinate and altitude coordinate of the ground point respectively;

[0067] Step 8: Projection space coordinates of the ground point obtained in step 7 , using spatial interpolation algorithm, the altitude coordinates Perform spatial interpolation, that is, generate the required digital terrain model, wherein the spatial interpolation algorithm includes but is not limited to the spline curve spatial interpolation algorithm, the Kriging spatial interpolation algorithm, the inverse distance weighted spatial interpolation algorithm, and the irregular triangulated network spatial interpolation algorithm.

[0068] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention shall be defined by the attached claims and their equivalents.

Claims

1. A surveying method for an unmanned aerial vehicle terrain surveying device based on laser ranging and a self-stabilizing gimbal, characterized in that: The surveying and mapping device comprises a multi-rotor unmanned aerial vehicle (1), an airborne GPS module (2), a self-stabilizing gimbal (3), and a laser ranging module (4), wherein the airborne GPS module (2) is fixedly mounted on the top of the multi-rotor unmanned aerial vehicle (1), the self-stabilizing gimbal (3) is arranged below the multi-rotor unmanned aerial vehicle (1), and the laser ranging module (4) is fixed on the bottom of the self-stabilizing gimbal (3) and emits and receives ranging laser signals vertically downward; The self-stabilizing pan-tilt platform (3) comprises a leveling plate (6), a servo motor (10), and a fixed plate (11); the fixed plate (11) is horizontally mounted at the bottom of a frame of the multi-rotor unmanned aerial vehicle (1); the leveling plate (6) is located below the fixed plate (11); an inclination sensor (5) is mounted on the leveling plate (6); and an external single-chip microcomputer control module for reading inclination sensor data is also arranged on the self-stabilizing pan-tilt platform (3); A plurality of servo motors (10) are evenly arranged on a fixed plate (11), a connecting rod mechanism is arranged between the fixed plate (11) and the leveling plate (6), the connecting rod mechanism comprises a hinge mechanism (7) and a connecting rod (8), the plurality of servo motors (10) are respectively connected to the connecting rod (8) via a rocker arm (9), and the other end of the connecting rod (8) is connected to the leveling plate (6) via the hinge mechanism (7); The surveying and mapping method mainly includes the following steps: Step 1: Set up a GPS base station at any location within 20 kilometers of the survey area, use GPS equipment to obtain the geographical coordinates (longitude, latitude and altitude) of the GPS base station, and use this coordinate as a reference to perform real-time dynamic correction or post-processing correction on the positioning data of the airborne GPS module (2) installed on the top of the multi-rotor drone to obtain the geographical coordinate sequence (x GPSi ,y GPSi ,h GPSi ), where x GPSi ,y GPSi 、h GPSi They are the longitude, latitude and altitude of the multi-rotor UAV terrain mapping system; Step 2: Set the flight route of the multi-rotor drone so that the ground measurement points have a spatial resolution of no less than 2 meters × 2 meters; Step 3: perform horizontal calibration on the self-stabilizing gimbal of the multi-rotor UAV terrain mapping system at a horizontal position on the ground to ensure that the leveling plate (6) is in a horizontal working state; Step 4: The multi-rotor UAV performs terrain mapping according to the pre-planned flight path. During the flight, the inclination angle of the UAV body changes continuously. The self-stabilizing gimbal of the multi-rotor UAV terrain mapping system performs horizontal correction so that the leveling plate remains horizontal and the laser transmitter and receiver of the laser ranging module (4) are vertically pointed to the ground. At this time, the laser ranging module (4) obtains the distance sequence h between the multi-rotor UAV terrain mapping device and the ground point directly below it at a frequency of 10 Hz. 激光i ; Step 5: The geographic coordinate sequence (x GPSi ,y GPSi ,h GPSi ) to extract the altitude sequence component h GPSi , the distance sequence h between the multi-rotor UAV terrain mapping device and the ground point directly below it obtained in step 4 激光i , the altitude of the ground point can be obtained h i =h GPSi -h 安装 -h 激光i ; Among them, h 安装 It is the height difference between the GPS rover antenna installed on the top of the multi-rotor drone and the laser transmitting and receiving lenses of the laser ranging module; Step 6: Use the altitude h of the ground point obtained in step 5 i Replace the geographic coordinates (x GPSi ,y GPSi ,h GPSi ) in the altitude sequence h GPSi , that is, to obtain the geographic coordinate sequence of the ground point (x GPSi ,y GPSi ,h i ), where x GPSi ,y GPSi 、h i are the longitude, latitude and altitude of the ground point respectively; Step 7: According to the longitude value x of the ground point GPSi , select the corresponding 3° or 6° band number, and obtain the projection plane coordinates (x eastingi ,y northingi ), using the projection plane coordinates (x eastingi ,y northingi ) instead of the geographic coordinate sequence of the ground point (x GPSi ,y GPSi ,h i ) in (x GPSi ,y GPSi ) coordinates, and finally obtain the projection space coordinates (x eastingi ,y northingi ,h i ), where x eastingi ,y northinai ,h i They are the easting coordinate, northing coordinate and altitude coordinate of the ground point respectively; Step 8: Based on the projection space coordinates (x eastingi ,y northingi ,h i ), using spatial interpolation algorithm, the altitude coordinate h i Perform spatial interpolation to generate the required digital terrain model.

2. The surveying and mapping method of the unmanned aerial vehicle terrain surveying and mapping device based on laser ranging and self-stabilizing pan-tilt according to claim 1 is characterized in that: The laser distance measurement module (4) is fixed vertically downward on the bottom of the leveling plate (6) of the self-stabilizing pan-tilt platform (3).

3. The surveying and mapping method of the unmanned aerial vehicle terrain surveying and mapping device based on laser ranging and self-stabilizing pan-tilt according to claim 1 is characterized in that: The number of the servo motors (10) is three, namely motor A, motor B, and motor C, and the three motors are centrally symmetrically distributed on the fixed disk (11) at an angle of 120°.

4. The surveying and mapping method of the unmanned aerial vehicle terrain surveying and mapping device based on laser ranging and self-stabilizing pan-tilt according to claim 1 is characterized in that: The GPS device in step 1 includes but is not limited to a high-precision real-time kinematic (RTK) GPS device.

5. The surveying and mapping method of the unmanned aerial vehicle terrain surveying and mapping device based on laser ranging and self-stabilizing pan-tilt platform according to claim 1 is characterized in that: The leveling control method for the self-stabilizing gimbal of the multi-rotor UAV terrain mapping system to perform horizontal correction in step 4 is: Step a, setting an X-axis and its positive direction along any radial direction in the plane of the fixed disk (11), rotating 90° counterclockwise from the established positive direction of the X-axis in the plane of the fixed disk (11) to obtain the positive direction of the Y-axis, and determining the positive direction of the Z-axis according to the right-hand rule. During the flight, the tilt angle of the drone body changes continuously, and the external single-chip control module obtains the reading of the tilt sensor (5) installed on the self-stabilizing gimbal leveling disk in real time, that is, the pitch angle change (rotation angle around the Y-axis) Δθ of the self-stabilizing gimbal when the drone body tilts. pitch The roll angle change (rotation angle around the X axis) Δθ roll , we get the leveling kinematic model of the self-stabilizing gimbal, which is: Dth A =a×Δθ pitch ; where Δθ A is the rotation angle of the output shaft of motor A, Δθ B is the rotation angle of the output shaft of motor B, Δθ C is the rotation angle of the output shaft of motor C, a is the proportional constant of the position of the motor output shaft, and f is the original stroke between the fixed plate and the leveling plate when the self-stabilizing gimbal is in the initial horizontal state; Step b: Based on the leveling kinematics model of the self-stabilizing gimbal obtained in step a, the external single-chip microcomputer control module uses a PID control algorithm to adjust the output shaft rotation angles Δθ of the three motors respectively. A , Δθ B , Δθ C , and then the corresponding rocker arm drives the connecting rod to move, dynamically compensating for the inclination change of the leveling plate, so that the leveling plate remains in a horizontal state.

6. The surveying and mapping method of the unmanned aerial vehicle terrain surveying and mapping device based on laser ranging and self-stabilizing pan-tilt platform according to claim 5 is characterized in that: The PID control algorithm in step b is: Δθ=K p ×θ(k)+K i ×∑θ(k)+K d ×[θ(k)-θ(k-1)]; Where: Δθ is the rotation angle of the motor output shaft; K p is the proportional control coefficient of the PID control algorithm; θ(k) is the angle deviation of this adjustment; K i is the integral control coefficient of the PID control algorithm; ∑θ(k) is the accumulation of angle deviation (k=1,2,…); K d is the differential control coefficient of the PID control algorithm; θ(k-1) is the angle deviation before adjustment.

7. The surveying and mapping method of the unmanned aerial vehicle terrain surveying and mapping device based on laser ranging and self-stabilizing pan-tilt platform according to claim 1 is characterized in that: The spatial interpolation algorithm in step eight includes but is not limited to a spline curve spatial interpolation algorithm, a Kriging spatial interpolation algorithm, an inverse distance weighted spatial interpolation algorithm, and an irregular triangulated network spatial interpolation algorithm.

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