Unmanned aerial vehicle target positioning system and positioning method

Abstract

The invention belongs to the technical field of unmanned aerial vehicle positioning, and particularly discloses an unmanned aerial vehicle target positioning system, which comprises an image acquisition module arranged at the bottom of an unmanned aerial vehicle and used for acquiring ground image information; the target identification module is used for identifying a target point in the ground image information; the coordinate conversion module is used for converting the GPS coordinates of the unmanned aerial vehicle into UTM coordinates; converting the projection coordinate of the target point into a geographic coordinate; the parameter calculation module is used for calculating a ground distance corresponding to a unit pixel; and based on the yaw angle of the unmanned aerial vehicle and the position of the target pixel point relative to the image center point, calculating the coordinate of the target point in the projection coordinate system by using the ground distance corresponding to the unit pixel. According to the method, the types and the number of sensors are simplified, only a basic visible light camera needs to be carried, the complexity and the cost of the system are reduced, image data can be rapidly processed through an optimization algorithm and an efficient data processing technology, and rapid recognition and positioning of a target are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicle positioning, and in particular relates to a unmanned aerial vehicle target positioning system and a positioning method. Background Art

[0002] In the field of geographic information and remote sensing technology, unmanned aerial vehicles (UAVs) have established themselves as an important tool for data collection. They have unique advantages in acquiring surface images in applications that require high-resolution and high-frequency monitoring. The combination of geographic information science and remote sensing technology has greatly advanced the understanding and analysis of the earth's surface features. The development of UAV technology, with its flexibility, cost-effectiveness and ability to get close to the ground, has brought new data collection methods to this field, making geospatial data richer and more real-time.

[0003] Existing drone target positioning technologies usually include image acquisition, which uses drones to take surface images; image preprocessing, which uses image processing algorithms to denoise and enhance contrast to improve the accuracy of target recognition; target recognition, which uses edge detection, deep learning and other technologies to identify specific targets in images; coordinate conversion, which converts the pixel coordinates of the target identified in the image into geographic coordinates. Existing drone target positioning technologies often face the following disadvantages: High sensor dependence: Many systems need to carry multiple types of sensors to obtain comprehensive information about the target area. This not only increases the payload of the drone, but also increases the cost and complexity of the system. Slow information processing: Existing technologies often take a long time to process image data and perform coordinate conversion. This limits the practicality of drones in application scenarios that require rapid response. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a UAV target positioning system and a positioning method.

[0005] A first aspect of the present invention provides a drone target positioning system, comprising:

[0006] An image acquisition module is provided at the bottom of the drone to obtain ground image information;

[0007] A target recognition module, connected to the image acquisition module, for identifying target points in ground image information;

[0008] The coordinate conversion module is used to convert the GPS coordinates of the drone into UTM coordinates, obtain the projection coordinates of the center point of the image, and convert the projection coordinates of the target point into geographic coordinates;

[0009] Parameter calculation module: Based on the flight parameters of the UAV and the image size, the ground distance corresponding to the unit pixel is calculated; and based on the yaw angle of the UAV and the position of the target pixel point relative to the center point of the image, the ground distance corresponding to the unit pixel is used to calculate the coordinates of the target point in the projection coordinate system.

[0010] A further solution is that the image acquisition module is a UAV wide-angle camera, and the UAV wide-angle camera obtains ground image information perpendicular to the ground.

[0011] A further solution is that the process of the coordinate conversion module converting the GPS coordinates of the drone into UTM coordinates is:

[0012] (C x ,C y )=WGS84_to_UTM(Lat center ,Lon center )

[0013] Among them, Lat center, Lon center is the image center point of the ground image information, C x ,C y are the projection coordinates of the center point of the transformed image.

[0014] A further solution is that the parameter calculation module includes a horizontal distance calculation unit and a pixel distance calculation unit;

[0015] The horizontal distance calculation unit is used to calculate the horizontal distance D of the shooting range of the UAV wide-angle camera:

[0016]

[0017] Where H is the flight height of the drone relative to the ground, in meters; θ is the wide-angle angle of the drone's wide-angle camera, in degrees;

[0018] The pixel distance calculation unit is used to calculate the actual ground distance corresponding to the unit pixel, and the calculation process is:

[0019] Get an image taken by a drone wide-angle camera, establish a pixel coordinate system with the upper left corner of the image as the origin O, horizontal to the right as the x-axis, vertical downward as the y-axis; define rows as the number of pixels in the y-axis direction of the photo, and cols as the number of pixels in the x-axis direction of the photo; in the pixel coordinate system, the x-axis is consistent with the horizontal distance D of the ground, and there is the following corresponding relationship:

[0020]

[0021] d rows =d cols

[0022] Among them, d cols , d rows They are the actual ground distances corresponding to the unit pixel in the x-axis direction and the y-axis direction, that is, the actual ground distance represented by the unit pixel, in meters / pixel.

[0023] A further solution is that the parameter calculation module also includes an angle calculation unit and a projection coordinate calculation unit, and the angle calculation unit is used to calculate the yaw angle α of the drone. img and the deflection angle α yaw The sum of the angles α is calculated as follows:

[0024] α yaw =calculateAngle(X t -X c ,Y t -Y c )

[0025] Δx=X t -X c Δy=Y t -Y c

[0026]

[0027] α yaw =round(α yaw )

[0028] α=α img +α yaw

[0029] Among them, X t , Y t is the target pixel coordinate; X c , Y c is the pixel coordinate of the center point of the image; atan2 is the inverse tangent function considering the quadrant, and its calculated value is an angle, which represents the distance from the center point of the image to the point (X t , Y t ) and the vertical direction, which is α yaw , ranging from -π to π, round(α yaw ) rounds the angle value to the nearest integer; α is the yaw angle α of the drone img The total angle calculated after the position of the target relative to the center of the image is the yaw angle α of the drone. img and the deflection angle α yaw The sum of the angles of

[0030] The projection coordinate calculation unit is used to calculate the projection coordinates (P x , P y), the calculation process is:

[0031]

[0032] A further solution is that the coordinate conversion module is also used to convert the projection coordinates (P x , P y ) is rotated to WGS84.

[0033] A second aspect of the present invention provides a method for positioning a target of an unmanned aerial vehicle, using the above positioning system, comprising the following steps:

[0034] Adjust the acquisition angle of the image acquisition module, adjust the image acquisition module to shoot perpendicular to the ground, and obtain ground image information;

[0035] Identify ground image information and obtain target points;

[0036] Convert the GPS coordinates of the drone into UTM coordinates to obtain the projection coordinates of the center point of the image;

[0037] Based on the flight parameters of the drone and the image size, calculate the ground distance corresponding to the unit pixel;

[0038] Using the yaw angle α of the drone img The position of the target pixel relative to the center of the image is used to calculate the projection coordinates of the target point based on the ground distance corresponding to the unit pixel;

[0039] Convert the projected coordinates of the target point to geographic coordinates.

[0040] A further solution is that when calculating the target projection coordinates, the following steps are included:

[0041] Calculate the deflection angle α of the target point relative to the center point of the image yaw ;

[0042] Calculate the deflection angle α yaw The yaw angle α with the drone img Add together to get the total angle α;

[0043] According to the value of α, the projection coordinates (P x , P y ).

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention simplifies the types and number of sensors and only requires a basic visible light camera, thereby reducing the complexity and cost of the system. By optimizing algorithms and adopting efficient data processing technology, it is possible to quickly process image data and achieve rapid identification and positioning of targets.

[0046] The invention has a fast processing speed and can achieve quasi-real-time processing (the actual frame rate depends on the video stream), giving users an intuitive and convenient observation experience. The solution can be obtained only by relying on visible light data and the flight attitude information of the drone itself.

[0047] In a flat terrain environment, all targets can be approximately on the same horizontal plane. At this time, the height of the drone relative to the ground is the height to this horizontal plane. In this scenario, there is no need to know the camera imaging-related parameters in advance to solve the actual ground distance corresponding to the unit pixel at this flight height. The solution process is simple and requires few steps and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The following drawings are only used to illustrate and explain the present invention, and are not used to limit the scope of the present invention, wherein:

[0049] Figure 1 : Schematic diagram of target positioning system connection structure;

[0050] Figure 2 :Drone shooting diagram;

[0051] Figure 3 :Schematic diagram of shooting ground image information;

[0052] Figure 4 : Schematic diagram of target projection coordinate solution;

[0053] Figure 5 : Flowchart of target positioning method implementation.

[0054] In the figure: 1. Image acquisition module; 2. Target recognition module; 3. Coordinate conversion module; 4. Parameter calculation module; 5. Pixel distance calculation unit; 6. Horizontal distance calculation unit; 7. Angle calculation unit; 8. Projection coordinate calculation unit. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution, design method and advantages of the present invention clearer, the present invention is further described in detail by specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] Example 1

[0057] like Figure 1 As shown, the present invention provides a UAV target positioning system, comprising:

[0058] An image acquisition module 1 is arranged at the bottom of the drone, and is used to acquire ground image information, wherein the image acquisition module 1 is a wide-angle camera of the drone, and the wide-angle camera of the drone acquires ground image information perpendicular to the ground;

[0059] A target recognition module 2, connected to the image acquisition module 1, for identifying target points in ground image information;

[0060] Coordinate conversion module 3, used to convert the GPS coordinates of the drone into UTM coordinates, obtain the projection coordinates of the center point of the image; and convert the projection coordinates of the target point into geographic coordinates;

[0061] Parameter calculation module 4: based on the flight parameters of the UAV and the image size, calculate the ground distance corresponding to the unit pixel; and based on the yaw angle of the UAV and the position of the target pixel point relative to the center point of the image, use the ground distance corresponding to the unit pixel to calculate the coordinates of the target point in the projection coordinate system.

[0062] In this embodiment, the process of the coordinate conversion module 3 converting the GPS coordinates of the drone into UTM coordinates is as follows:

[0063] (C x ,C y )=WGS84_to_UTM(Lat center ,Lon center )

[0064] Among them, Lat center, Lon center is the image center point of the ground image information, C x ,C y are the projection coordinates of the center point of the transformed image.

[0065] In this embodiment, the GDAL development library is used as an example to implement the conversion of the GPS coordinates of the drone into UTM coordinates:

[0066] (1) Declare OGRSpatialReference type variables source_oSRS and target_oSRS.

[0067] (2) Call the SetWellKnownGeogCS() method to initialize the spatial reference object:

[0068] source_oSRS.SetWellKnownGeogCS("WGS84");

[0069] target_oSRS.SetWellKnownGeogCS("WGS84");

[0070] In this method, the WGS 84 coordinate system is used to initialize the spatial reference object.

[0071] (3) Using importFromEPSG(), then:

[0072] source_oSRS.importFromEPSG(4326);

[0073] target_oSRS.importFromEPSG(32651);

[0074] (4) Declare a variable poCT of type OGRCoordinateTransformation* and call OGRCreateCoodinateTransformation(&source_oSRS,&target_oSRS).

[0075] (5) Call poCT->Transform(1,&latitude,&longitude) for conversion. Latitude and longitude are the original GPS coordinates, and the converted coordinate values ​​will overwrite latitude and longitude.

[0076] (6) Return the converted coordinate value.

[0077] In the above, the parameter calculation module 4 includes a horizontal distance calculation unit 6 and a pixel distance calculation unit 5;

[0078] like Figure 2 As shown, the horizontal distance calculation unit 6 is used to calculate the horizontal distance D of the shooting range of the drone wide-angle camera:

[0079]

[0080] Where H is the flight height of the UAV relative to the ground, in meters; θ is the wide-angle angle of the UAV wide-angle camera, in degrees;

[0081] like Figure 3 As shown, the pixel distance calculation unit 5 is used to calculate the actual ground distance corresponding to the unit pixel, and the calculation process is:

[0082] Get an image taken by a drone wide-angle camera, establish a pixel coordinate system with the upper left corner of the image as the origin O, horizontal to the right as the x-axis, vertical downward as the y-axis; define rows as the number of pixels in the y-axis direction of the photo, and cols as the number of pixels in the x-axis direction of the photo; in the pixel coordinate system, the x-axis is consistent with the horizontal distance D of the ground, and there is the following corresponding relationship:

[0083]

[0084] d rows =d cols

[0085] Among them, d cols , d rows They are the actual ground distances corresponding to the unit pixel in the x-axis direction and the y-axis direction, that is, the actual ground distance represented by the unit pixel, in meters / pixel.

[0086] In the above, if Figure 4 As shown, the parameter calculation module 4 also includes an angle calculation unit 7 and a projection coordinate calculation unit 8. The angle calculation unit 7 is used to calculate the yaw angle α of the drone. img and the deflection angle α yaw The sum of the angles α is calculated as follows:

[0087] α yaw =calculateAngle(X t -X c ,Y t -Y c )

[0088] Δx=X t -X c Δy=Y t -Y c

[0089]

[0090] α yaw =round(α yaw )

[0091] α=α img +α yaw

[0092] Among them, X t , Y t is the target pixel coordinate; X c , Y c is the pixel coordinate of the center point of the image; atan2 is the inverse tangent function considering the quadrant, and its calculated value is an angle, which represents the distance from the center point of the image to the point (X t , Y t ) and the vertical direction, which is α yaw , ranging from -π to π, round(α yaw ) rounds the angle value to the nearest integer; α is the yaw angle α of the drone img The total angle calculated after the position of the target relative to the center of the image is the yaw angle α of the drone. img and the deflection angle α yaw The sum of the angles of

[0093] The projection coordinate calculation unit 8 is used to calculate the projection coordinates (Px , P y ), the calculation process is:

[0094]

[0095] In the above, the coordinate conversion module 3 is also used to convert the projection coordinates (P x , P y ) is rotated to WGS84.

[0096] In this embodiment, the GDAL development library is used as an example to implement the projection coordinates (P x , P y ) to WGS84, the specific process is:

[0097] Implementation method: Take the GDAL development library as an example:

[0098] (1) Declare OGRSpatialReference type variables source_oSRS and target_oSRS.

[0099] (2) Call the SetWellKnownGeogCS() method to initialize the spatial reference object:

[0100] source_oSRS.SetWellKnownGeogCS("WGS 84");

[0101] target_oSRS.SetWellKnownGeogCS("WGS 84");

[0102] In this method, the WGS 84 coordinate system is used to initialize the spatial reference object.

[0103] (3) Using importFromEPSG(), then:

[0104] source_oSRS.importFromEPSG(32651);

[0105] target_oSRS.importFromEPSG(4326);

[0106] (4) Declare a variable poCT of type OGRCoordinateTransformation* and call OGRCreateCoodinateTransformation(&source_oSRS,&target_oSRS).

[0107] (5) Call poCT->Transform(1,&latitude,&longitude) for conversion. Latitude and longitude are the original GPS coordinates, and the converted coordinate values ​​will overwrite latitude and longitude.

[0108] (6) Return the converted coordinate value.

[0109] Example 2

[0110] like Figure 5 As shown, this embodiment provides a method for positioning a drone target, using the positioning system of embodiment 1, including the following steps:

[0111] Adjust the acquisition angle of the image acquisition module 1, adjust the image acquisition module 1 to shoot perpendicular to the ground, and obtain ground image information;

[0112] Identify ground image information and obtain target points;

[0113] Convert the GPS coordinates of the drone into UTM coordinates to obtain the projection coordinates of the center point of the image;

[0114] Based on the flight parameters of the drone and the image size, calculate the ground distance corresponding to the unit pixel;

[0115] Using the yaw angle α of the drone img The position of the target pixel relative to the center of the image is used to calculate the projection coordinates of the target point based on the ground distance corresponding to the unit pixel;

[0116] Convert the projected coordinates of the target point to geographic coordinates.

[0117] Specifically, when calculating the target projection coordinates, the following steps are included:

[0118] Calculate the deflection angle α of the target point relative to the center point of the image yaw ;

[0119] Calculate the deflection angle α yaw The yaw angle α with the drone img Add together to get the total angle α;

[0120] According to the value of α, the projection coordinates of the target point (P x , P y ).

[0121] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A drone target positioning system, characterized in that: include: An image acquisition module is provided at the bottom of the drone to obtain ground image information; A target recognition module, connected to the image acquisition module, for identifying target points in ground image information; The coordinate conversion module is used to convert the GPS coordinates of the drone into UTM coordinates, obtain the projection coordinates of the center point of the image, and convert the projection coordinates of the target point into geographic coordinates; Parameter calculation module: Based on the flight parameters of the UAV and the image size, the ground distance corresponding to the unit pixel is calculated; and based on the yaw angle of the UAV and the position of the target pixel point relative to the center point of the image, the ground distance corresponding to the unit pixel is used to calculate the coordinates of the target point in the projection coordinate system.

2. The unmanned aerial vehicle target positioning system according to claim 1, characterized in that: The image acquisition module is a UAV wide-angle camera, and the UAV wide-angle camera acquires ground image information perpendicular to the ground.

3. The unmanned aerial vehicle target positioning system according to claim 2, characterized in that: The process of converting the GPS coordinates of the drone into UTM coordinates by the coordinate conversion module is as follows: (C x ,C y )=WGS84_to_UTM(Lat center ,Lon center ) Among them, Lat center, Lon center is the image center point of the ground image information, C x ,C y are the projection coordinates of the center point of the transformed image.

4. The unmanned aerial vehicle target positioning system according to claim 3, characterized in that: The parameter calculation module includes a horizontal distance calculation unit and a pixel distance calculation unit; The horizontal distance calculation unit is used to calculate the horizontal distance D of the shooting range of the UAV wide-angle camera: Where H is the flight height of the UAV relative to the ground, in meters; θ is the wide-angle angle of the UAV wide-angle camera, in degrees; The pixel distance calculation unit is used to calculate the actual ground distance corresponding to the unit pixel, and the calculation process is: Get an image taken by a drone wide-angle camera, establish a pixel coordinate system with the upper left corner of the image as the origin O, horizontal to the right as the x-axis, vertical downward as the y-axis; define rows as the number of pixels in the y-axis direction of the photo, and cols as the number of pixels in the x-axis direction of the photo; in the pixel coordinate system, the x-axis is consistent with the horizontal distance D of the ground, and there is the following corresponding relationship: d rows =d cols Among them, d cols , d rows They are the actual ground distances corresponding to the unit pixel in the x-axis direction and the y-axis direction, that is, the actual ground distance represented by the unit pixel, in meters / pixel.

5. The unmanned aerial vehicle target positioning system according to claim 4, characterized in that: The parameter calculation module also includes an angle calculation unit and a projection coordinate calculation unit. The angle calculation unit is used to calculate the yaw angle α of the drone. img and the deflection angle α yaw The sum of the angles α is calculated as follows: a yaw =calculateAngle(X t -X c ,AND t -AND c ) Δx=X t -X c Δy=Y t -Y c a yaw =round(a yaw ) α＝α img +α yaw Among them, X t , Y t is the target pixel coordinate; X c , Y c is the pixel coordinate of the center point of the image; atan2 is the inverse tangent function considering the quadrant, and its calculated value is an angle, which represents the distance from the center point of the image to the point (X t , Y t ) and the vertical direction, which is α yaw , ranging from -π to π, round(α yaw ) rounds the angle value to the nearest integer; α is the yaw angle α of the drone img The total angle calculated after the position of the target relative to the center of the image is the yaw angle α of the drone. img and the deflection angle α yaw The sum of the angles of The projection coordinate calculation unit is used to calculate the projection coordinates (P x , P y ), the calculation process is:

6. The unmanned aerial vehicle target positioning system according to claim 5, characterized in that: The coordinate conversion module is also used to convert the projection coordinates (P x , P y ) is rotated to WGS84.

7. A method for positioning a drone target, characterized in that: The positioning system according to any one of claims 1 to 6 is applied, comprising the following steps: Adjust the acquisition angle of the image acquisition module, adjust the image acquisition module to shoot perpendicular to the ground, and obtain ground image information; Identify ground image information and obtain target points; Convert the GPS coordinates of the drone into UTM coordinates to obtain the projection coordinates of the center point of the image; Based on the flight parameters of the drone and the image size, calculate the ground distance corresponding to the unit pixel; Using the yaw angle α of the drone img The position of the target pixel relative to the center of the image is used to calculate the projection coordinates of the target point based on the ground distance corresponding to the unit pixel; Convert the projected coordinates of the target point to geographic coordinates.

8. The unmanned aerial vehicle target positioning system according to claim 7, characterized in that: When calculating the target projection coordinates, the following steps are included: Calculate the deflection angle α of the target point relative to the center point of the image yaw ; Calculate the deflection angle α yaw The yaw angle α with the drone img Add together to get the total angle α; According to the value of α, the projection coordinates of the target point (P x , P y ).

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