A UAV target positioning system and positioning method

Abstract

The present invention belongs to the field of drone positioning technology and specifically discloses a drone target positioning system, comprising: an image acquisition module disposed on the bottom of the drone, for acquiring ground image information; a target recognition module, for identifying target points in the ground image information; a coordinate conversion module, for converting the drone's GPS coordinates into UTM coordinates; and converting the projected coordinates of the target point into geographic coordinates; a parameter calculation module, for calculating the ground distance corresponding to a unit pixel; and, based on the drone's yaw angle and the position of the target pixel relative to the image center point, calculating the coordinates of the target point in the projected coordinate system using the ground distance corresponding to the unit pixel. The present invention simplifies the types and number of sensors, requiring only a basic visible light camera, reducing system complexity and cost. By optimizing algorithms and employing efficient data processing techniques, the system can rapidly process image data, enabling rapid target identification and positioning.

Description

Technical Field

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

[0002] In the fields of geographic information and remote sensing, unmanned aerial vehicles (UAVs) have established themselves as essential tools for data collection. They offer unique advantages for acquiring surface imagery in applications requiring high-resolution and high-frequency monitoring. The integration of geographic information science and remote sensing has significantly advanced our understanding and analysis of Earth's surface features. The development of UAV technology, with its flexibility, cost-effectiveness, and ability to operate 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 technology typically includes image acquisition, where drones capture surface images; image preprocessing, where image processing algorithms are used to perform denoising and contrast enhancement on the images to improve target recognition accuracy; target recognition, where edge detection, deep learning, and other techniques are applied to identify specific targets in the image; and coordinate conversion, where the pixel coordinates of the target identified in the image are converted into geographic coordinates. Existing drone target positioning technology often suffers from the following shortcomings: High sensor dependency: Many systems require 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 require a long time to process image data and perform coordinate conversions. 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 positioning method.

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

[0006] The image acquisition module is set at the bottom of the drone and is used 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 image center point, and convert the projection coordinates of the target point into geographic coordinates;

[0009] Parameter calculation module: Based on the UAV's flight parameters and image size, the ground distance corresponding to the unit pixel is calculated; and based on the UAV's yaw angle and the position of the target pixel 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 projected coordinate system.

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

[0011] A further solution is that the coordinate conversion module converts the GPS coordinates of the drone into UTM coordinates as follows:

[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 is the projection coordinate 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 UAV wide-angle camera shooting range:

[0016]

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

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

[0019] Get an image captured by a drone's wide-angle camera. Establish a pixel coordinate system with the upper-left corner of the image as the origin, O. The x-axis extends horizontally to the right, and the y-axis extends vertically downward. Define rows as the number of pixels along the y-axis of the image, and cols as the number of pixels along the x-axis. In the pixel coordinate system, the x-axis is aligned with the horizontal distance D from the ground, and the following correspondence exists:

[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 further includes an angle calculation unit and a projection coordinate calculation unit, wherein the angle calculation unit is used to calculate the yaw angle α of the drone. img and 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 the 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 by adding the position of the target relative to the center of the image is the yaw angle α of the drone. img and deflection angle α yaw The sum of the angles of

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

[0031]

[0032] A further solution is that the coordinate conversion module is further 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 locating a target of an unmanned aerial vehicle (UAV), using the above-mentioned positioning system, comprising the following steps:

[0034] Adjust the acquisition angle of the image acquisition module to shoot perpendicular to the ground to 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] Calculate the ground distance per pixel based on the UAV's flight parameters and image size;

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

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

[0040] A further solution is to include the following steps when calculating the target projection coordinates:

[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 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 of the target point (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, reducing the complexity and cost of the system. By optimizing algorithms and adopting efficient data processing technology, it can quickly process image data and achieve rapid identification and positioning of targets.

[0046] The present 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 performed only based on visible light data and the drone's own flight attitude information.

[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 ground true distance corresponding to the unit pixel at this flight altitude. The solution process is simple and requires few steps and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The following drawings are merely provided for illustrative purposes only and are not intended to limit the scope of the present invention.

[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 more clear, the present invention is further described in detail below through 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 provided at the bottom of the drone, and is used to acquire ground image information. 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 image center point; and convert the projection coordinates of the target point into geographic coordinates;

[0061] Parameter calculation module 4: Calculates the ground distance per unit pixel based on the UAV's flight parameters and image size; and calculates the coordinates of the target point in the projected coordinate system using the ground distance per unit pixel based on the UAV's yaw angle and the position of the target pixel relative to the image center.

[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 is the projection coordinate of the center point of the transformed image.

[0065] In this example, the GDAL development library is used as an example to convert 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] This method uses the WGS 84 coordinate system to initialize the spatial reference object.

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

[0072] source_oSRS.importFromEPSG(4326);

[0073] target_oSRS.importFromEPSG(32651);

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

[0075] (5) Call poCT->Transform(1,&latitude,&longitude) to perform the transformation. Latitude and longitude are the original GPS coordinates, and the transformed 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 UAV wide-angle camera:

[0079]

[0080] Where H is the flight altitude of the UAV relative to the ground, in meters; θ is the wide-angle angle of the UAV's 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 captured by a drone's wide-angle camera. Establish a pixel coordinate system with the upper-left corner of the image as the origin, O. The x-axis extends horizontally to the right, and the y-axis extends vertically downward. Define rows as the number of pixels along the y-axis of the image, and cols as the number of pixels along the x-axis. In the pixel coordinate system, the x-axis is aligned with the horizontal distance D from the ground, and the following correspondence exists:

[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 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 the 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 by adding the position of the target relative to the center of the image is the yaw angle α of the drone. img and deflection angle α yaw The sum of the angles of

[0093] The projection coordinate calculation unit 8 is used to calculate the projection coordinates of the target point (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 of the target point (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] This method uses the WGS 84 coordinate system to initialize the spatial reference object.

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

[0104] source_oSRS.importFromEPSG(32651);

[0105] target_oSRS.importFromEPSG(4326);

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

[0107] (5) Call poCT->Transform(1,&latitude,&longitude) to perform the transformation. Latitude and longitude are the original GPS coordinates, and the transformed 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 Example 1, including the following steps:

[0111] Adjust the acquisition angle of the image acquisition module 1 so that it is perpendicular to the ground to 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] Calculate the ground distance per pixel based on the UAV's flight parameters and image size;

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

[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 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] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A UAV target positioning system, characterized in that: include: The image acquisition module is set at the bottom of the drone and is used 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 image center point, and convert the projection coordinates of the target point into geographic coordinates; Parameter calculation module: Calculates the ground distance per unit pixel based on the drone's flight parameters and image size. Also, calculates the coordinates of the target point in the projected coordinate system using the ground distance per unit pixel based on the drone's yaw angle and the position of the target pixel relative to the image center. The image acquisition module is a wide-angle camera of a UAV, which is perpendicular to the ground to obtain ground image information; 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 UAV wide-angle camera shooting range: Where H is the flight altitude of the UAV relative to the ground, in meters; θ is the wide-angle angle of the UAV's wide-angle camera, in degrees; The pixel distance calculation unit is used to calculate the actual ground distance corresponding to a unit pixel. The calculation process is: Get an image captured by a drone's wide-angle camera. Establish a pixel coordinate system with the upper-left corner of the image as the origin, O. The x-axis extends horizontally to the right, and the y-axis extends vertically downward. Define rows as the number of pixels along the y-axis of the image, and cols as the number of pixels along the x-axis. In the pixel coordinate system, the x-axis is aligned with the horizontal distance D from the ground, and the following correspondence exists: d rows =d cols Among them, d cols , d rows The actual ground distances in the x-axis and y-axis directions corresponding to the unit pixel, that is, the actual ground distance represented by the unit pixel, in meters / pixel; 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 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 r-yaw =round(a yaw ) α＝α img +α r-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 the 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, α r-yaw is to convert α yaw The angle value is rounded to the nearest integer; α is the yaw angle of the drone img The total angle calculated by adding the position of the target relative to the center of the image is the yaw angle α of the drone. img and deflection angle α yaw The sum of the angles of The projection coordinate calculation unit is used to calculate the projection coordinates of the target point (P x , P y ), the calculation process is: 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 is the projection coordinate of the center point of the transformed image.

2. The UAV target positioning system according to claim 1, characterized in that: The coordinate conversion module is also used to convert the projection coordinates of the target point (P x , P y ) is rotated to WGS84.

3. A method for positioning a target of an unmanned aerial vehicle, characterized in that: The positioning system according to any one of claims 1 to 2 comprises the following steps: Adjust the acquisition angle of the image acquisition module to shoot perpendicular to the ground to 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; Calculate the ground distance per pixel based on the UAV's flight parameters and image size; Using the drone's yaw angle α img The position of the target pixel relative to the center of the image and the ground distance corresponding to the unit pixel are used to calculate the projection coordinates of the target point; Convert the projected coordinates of the target point to geographic coordinates.

4. The method for positioning a target of an unmanned aerial vehicle according to claim 3, wherein: 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 Yaw angle α with the drone img Add up the total angle α; according to the value of α, use trigonometric functions to calculate the projection coordinates of the target point (P x , P y ).

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