A UAV target positioning method based on geographic information

Abstract

The present invention discloses a method for positioning unmanned aerial vehicle (UAV) targets based on geographic information, comprising the following steps: S1, acquiring basic parameters during takeoff; S2, detecting real-time data during flight control; S3, calculating the aircraft's altitude; S4, calculating the latitude and longitude corresponding to zero altitude B at the center of the field of view; and S5, resolving target coordinates. This method provides a method for positioning UAV targets based on geographic information. This method can accurately locate the target's precise latitude and altitude using a common optical pod, and the calculation is performed using background computing on a ground station computer, reducing processing pressure on the airborne control computer.

Description

Technical Field

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

[0002] At present, the method of using drones for image acquisition has been widely used. On the basis of image acquisition by drones, the targets in the images are further located. For example, when using drones to search for lost people or lost livestock, after collecting the targets, the targets need to be located; or when using drones to search for fire points in the forest, the location of the fire points needs to be further obtained.

[0003] Drone target positioning relies on pod ranging to obtain slant range, and the target's precise latitude is calculated based on the pod's pitch and azimuth angles, the drone's positioning, and its relative takeoff altitude. This requires the use of a high-cost pod with laser ranging to more accurately calculate target coordinates, and cannot obtain geographic information such as the target's altitude. The calculation process requires the flight controller's computer processor threads, affecting the flight control processing capability. Summary of the Invention

[0004] The purpose of the present invention is to provide a UAV target positioning method based on geographic information, which can accurately locate the target's latitude and altitude by using an ordinary optical pod, and the solution uses the background calculation of the ground station computer to reduce the processing pressure of the air control computer.

[0005] The technical solution adopted by the UAV target positioning method based on geographic information disclosed in the present invention is:

[0006] A method for positioning a target of an unmanned aerial vehicle based on geographic information comprises the following steps:

[0007] S1, basic parameters acquisition during the takeoff phase, obtaining the takeoff state latitude and longitude of the drone before takeoff and the takeoff point altitude H0;

[0008] S2 detects real-time data during the flight control phase, including the UAV’s latitude and longitude, relative takeoff altitude h, magnetic direction angle θ, pod pitch angle η, and direction angle σ;

[0009] S3, calculate the altitude of the drone. The current latitude and longitude A of the drone corresponds to the altitude H1 in the geographic information database. Calculate the altitude of the drone: H = H0 - H1 + h;

[0010] S4, calculate the latitude and longitude corresponding to the zero altitude B of the center point of the field of view, calculate the magnetic direction angle α = θ + σ of the pod's pointing direction; calculate the horizontal distance L = H * tanη between the target and the drone; use the function to know the current longitude E and latitude W, the magnetic direction angle α, and the horizontal distance L, so as to calculate the zero altitude latitude and longitude of the center point of the pod's field of view;

[0011] S5, solve the target coordinates, connect the current point and altitude of the UAV with the zero altitude point of the pod field of view center point to establish a cross-section; query the geographic information database and find the first intersection of the connecting line with the contour line as the target point X; use geographic information to query the latitude and longitude of point X and the corresponding altitude; solve the real target coordinates method.

[0012] As a preferred solution, S6, parameter correction, is also included. If the take-off point is not the original terrain, there will be a relative distance difference between the take-off point and the altitude point. The actual take-off point altitude is calculated and substituted into the algorithm, that is, the altitude of the drone is corrected: H = H0-H1+h+relative distance difference.

[0013] As a preferred option, when the take-off point is higher than the altitude point or lower than the altitude point, the ground station software can be used to input the altitude difference parameter, calculate the actual take-off point altitude and substitute it into the algorithm. If the target terrain changes, the ground station software can be used to manually select the target point and correct the final target latitude, longitude and altitude.

[0014] As a preferred solution, the specific calculation method in step S4 is:

[0015] S4-1, based on the Earth's radius of 6371 km and the height difference of 7.84 meters per 10 kilometers, the curvature of the Earth's radius can be ignored, so L is the straight-line distance between points AB;

[0016] S4-2, take an intermediate point C, whose longitude is the same as A and latitude is the same as B, then Lac = L*cosα, Lbc = L*sinα;

[0017] S4-3, calculate the latitude angle between BC k = W * 0.017453 + asin (Lac / 6371) / 2;

[0018] S4-4, calculate the longitude offset l = asin(Lbc / (12742*cosk))*2;

[0019] S4-5, calculate the zero altitude longitude E0 and latitude W0 of the pod field of view center point, E0 = E + l * 0.017453, W0 = k * 0.017453.

[0020] As a preferred solution, the specific calculation method in step S5 is: given the longitude E, latitude W and altitude H of the current point of the drone and the longitude E0 and latitude W0 of the zero altitude point of the pod's field of view center point;

[0021] S5-1, connect the line from (E, W) to (E0, W0), and each point on the line is (En, Wn), and the altitude is Hn;

[0022] S5-2, calculate the distance from each point on the line to the center of the pod field of view, zero altitude point D = 6371*arccos(sin(W0*0.017453)*sin(Wn*0.017453)+cos(W0*0.017453)*cos(Wn*0.017453)*cos((E0-En)*0.017453));

[0023] S5-3, calculate Hx=Hn / D*L;

[0024] S5-4, compare Hx with H. If Hx ≥ H, record the longitude Enx, Wnx and altitude Hnx of the point;

[0025] S6-5, after all points in the line are compared, find the maximum value of x, that is, the longitude Enxmax, latitude Wnxmax and altitude Hnxmax of the target geographic information value of the center point of the pod field of view.

[0026] The beneficial effects of the UAV target positioning method based on geographic information disclosed by the present invention are as follows: the three-dimensional solution target is planarized through parameters such as the pod angle and the position height of the UAV, and the geographic contour vector diagram is called to improve data accuracy and obtain the target point altitude, so as to be free from the hardware restrictions such as the pod, and the longitude and latitude and altitude of the pod field of view center point can be located at a long distance; the target longitude and latitude and altitude are calculated by using a ground station computer, reducing the flight control solution pressure; the algorithm versatility is improved, and it is not restricted by the pod brand. Only the pod direction angle and pitch angle parameters need to be opened to automatically solve the target geographic information. The target latitude and altitude can be accurately located using an ordinary optical pod, and the solution uses the background calculation of the ground station computer to reduce the processing pressure of the air control computer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flowchart of a method for locating a target of an unmanned aerial vehicle based on geographic information. DETAILED DESCRIPTION

[0028] The present invention will be further described and explained below in conjunction with specific embodiments and accompanying drawings:

[0029] Please refer to Figure 1 , a UAV target positioning method based on geographic information, comprising the following steps:

[0030] S1, basic parameters acquisition during the takeoff phase, obtain the takeoff state latitude and longitude of the drone before takeoff and the takeoff point altitude H0.

[0031] It can be directly obtained through the data in the corresponding geographic information database and the corresponding record number can be assigned.

[0032] S2 detects the real-time data of the flight control phase, including the longitude and latitude of the UAV, the relative take-off altitude h, the magnetic direction angle θ, the pod pitch angle η and the direction angle σ.

[0033] The drone is connected to the Internet using its own sensors and positioning modules to transmit real-time data and retrieve the corresponding geographic location information based on the required information.

[0034] S3, calculate the altitude of the drone. The current latitude and longitude A of the drone corresponds to the altitude H1 in the geographic information database. Calculate the altitude of the drone: H = H0 - H1 + h

[0035] S4, calculate the longitude and latitude corresponding to the zero altitude B of the center point of the field of view, calculate the magnetic direction angle α = θ + σ of the pod's pointing direction; calculate the horizontal distance L = H * tanη between the target and the drone; use the function to know the current longitude E and latitude W, the magnetic direction angle α, and the horizontal distance L, so as to calculate the longitude and latitude of the zero altitude of the center point of the pod's field of view.

[0036] The specific calculation method in step S4 is:

[0037] S4-1, the approximate value of the earth's curvature is negligible. Based on the earth's radius of 6371 km, the height difference per 10 kilometers is only 7.84 meters. Currently, the visual range of various optical cameras generally does not exceed 10 kilometers. The curvature of the earth's radius can be ignored, and L is the straight-line distance between points AB;

[0038] S4-2, take an intermediate point C, whose longitude is the same as A and latitude is the same as B, then Lac = L*cosα, Lbc = L*sinα;

[0039] S4-3, calculate the latitude angle between BC k = W * 0.017453 + asin (Lac / 6371) / 2, where π / 180 = 0.017453;

[0040] S4-4, calculate the longitude offset l = asin(Lbc / (12742*cosk))*2;

[0041] S4-5, calculate the zero altitude longitude E0 and latitude W0 of the pod field of view center point, E0 = E + l * 0.017453, W0 = k * 0.017453.

[0042] S5, solve the target coordinates, connect the current point and altitude of the UAV with the zero altitude point of the pod field of view center point to establish a cross-section; query the geographic information database and find the first intersection of the connecting line with the contour line as the target point X; use geographic information to query the latitude and longitude of point X and the corresponding altitude; solve the real target coordinates method.

[0043] The specific calculation method in step S5 is: given the longitude E, latitude W and altitude H of the current point of the drone and the longitude E0 and latitude W0 of the zero altitude point of the pod's field of view center;

[0044] S5-1, connect the line from (E, W) to (E0, W0), and each point on the line is (En, Wn), and the altitude is Hn;

[0045] S5-2, calculate the distance from each point on the line to the center of the pod field of view, zero altitude point D = 6371*arccos(sin(W0*0.017453)*sin(Wn*0.017453)+cos(W0*0.017453)*cos(Wn*0.017453)*cos((E0-En)*0.017453));

[0046] S5-3, calculate Hx=Hn / D*L;

[0047] S5-4, compare Hx with H. If Hx ≥ H, record the longitude Enx, Wnx and altitude Hnx of the point;

[0048] S6-5, after all points in the line are compared, find the maximum value of x, that is, the longitude Enxmax, latitude Wnxmax and altitude Hnxmax of the target geographic information value of the center point of the pod field of view.

[0049] The above scheme also includes S6, parameter correction. If the take-off point is not the original terrain, the actual take-off point altitude is calculated and substituted into the algorithm, that is, the altitude of the drone is corrected: H = H0-H1+h+relative distance difference.

[0050] If the takeoff point is higher or lower than the altitude point, the ground station software can be used to input the altitude difference parameter, calculate the actual takeoff point altitude and substitute it into the algorithm. If the target terrain changes, the ground station software can be used to manually select the target point and correct the final target latitude, longitude and altitude. This can reduce the error caused by the difference between the actual altitude and the altitude in the geographic information during takeoff.

[0051] The present invention provides a UAV target positioning method based on geographic information. The method converts a three-dimensional target solution into a planar one by using parameters such as the pod angle and the UAV position altitude, and calls a geographic contour vector diagram to improve data accuracy and obtain the target point altitude. Thus, the method is not restricted by hardware such as the pod, and the longitude, latitude and altitude of the pod field of view center point can be located at a long distance. The method uses a ground station computer to calculate the target longitude, latitude and altitude, thereby reducing the flight control solution pressure. The method improves the algorithm versatility and is not restricted by pod brand. Only the pod direction angle and pitch angle parameters need to be opened to automatically solve the target geographic information. The target latitude and altitude can be accurately located using an ordinary optical pod. The solution uses background calculations on the ground station computer, thereby reducing the processing pressure on the air control computer.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for positioning a UAV target based on geographic information, characterized in that: The following steps are involved: S1, basic parameters acquisition during the takeoff phase, obtaining the takeoff state latitude and longitude of the drone before takeoff and the takeoff point altitude H0; S2 detects real-time data during the flight control phase, including the UAV’s latitude and longitude, relative takeoff altitude h, magnetic direction angle θ, pod pitch angle η, and direction angle σ; S3, calculate the altitude of the drone. The current latitude and longitude A of the drone corresponds to the altitude H1 in the geographic information database. Calculate the altitude of the drone: H = H0 - H1 + h; S4, calculate the latitude and longitude corresponding to the zero altitude B of the center point of the field of view, calculate the magnetic direction angle α=θ+σ of the pod; calculate the horizontal distance L=H*tanη between the target and the drone; Using the function, the current longitude E and latitude W, magnetic direction angle α, and horizontal distance L are known, so the zero altitude longitude and latitude of the pod field of view center point can be calculated; The specific calculation method in step S4 is: S4-1, based on the Earth's radius of 6371 km, the height difference of 7.84 meters per 10 kilometers, and the Earth's radius curvature being negligible, then L is the straight-line distance between points AB; S4-2, take an intermediate point C, whose longitude is the same as A and latitude is the same as B, then Lac=L*cosα, Lbc=L*sinα; S4-3, calculate the latitude angle between BC k = W * 0.017453 + asin (Lac / 6371) / 2; S4-4, calculate the longitude offset l = asin(Lbc / (12742*cosk))*2; S4-5, calculate the zero altitude longitude E0 and latitude W0 of the pod field of view center point, E0=E+l*0.017453, W0=k*0.017453; S5, solve the target coordinates, connect the current point and altitude of the UAV with the zero altitude point of the pod field of view center point to establish a cross-section diagram; Query the geographic information database and find the first intersection of the line and the contour line as the target point X; use geographic information to query the latitude and longitude of point X and the corresponding altitude; and calculate the true target coordinates; The specific calculation method in step S5 is: given the longitude E, latitude W and altitude H of the current point of the drone and the longitude E0 and latitude W0 of the zero altitude point of the pod's field of view center; S5-1, connect the line from (E, W) to (E0, W0), and each point on the line is (En, Wn), with the altitude being Hn; S5-2, calculate the distance from each point on the line to the center of the pod's field of view, zero altitude point D = 6371 * arccos (sin (W0 * 0.017453) * sin (Wn * 0.017453) + cos (W0 * 0.017453) * cos (Wn * 0.017453) * cos ((E0 - En) * 0.017453)); S5-3, calculate Hx = Hn / D * L; S5-4, compare Hx with H. If Hx ≥ H, record the longitude Enx, Wnx and altitude Hnx of the point; S5-5, after all points within the line are compared, find the maximum value of the target geographic information of the pod field of view center point x, that is, the longitude Enxmax, the latitude Wnxmax and the altitude Hnxmax.

2. The method for positioning a target of an unmanned aerial vehicle based on geographic information according to claim 1, wherein: It also includes S6, parameter correction. If the take-off point is not the original terrain, there will be a relative distance difference between the take-off point and the altitude point. The actual take-off point altitude is calculated and substituted into the algorithm to correct the drone altitude: H = H0-H1+h+relative distance difference.

3. The method for positioning a target of an unmanned aerial vehicle based on geographic information according to claim 2, wherein: When the take-off point is higher than the altitude point or lower than the altitude point, the ground station software can be used to input the altitude difference parameter, calculate the actual take-off point altitude and substitute it into the algorithm. If the target terrain changes, the ground station software can be used to manually select the target point and correct the final target latitude, longitude and altitude.

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