A method for multiple measurement and positioning of ground target geographical location by fixed-wing UAV

Abstract

The present invention discloses a method for multiple measurement and positioning of the geographical location of a ground target by a fixed-wing unmanned aerial vehicle. The fixed-wing unmanned aerial vehicle performs a desired route mission at a constant speed and fixed altitude; the image is captured by a pan-tilt camera on the fixed-wing unmanned aerial vehicle, and the image is monitored in real time. If the target appears in the image and is not located in the central area of ​​the image, the adjustment state is entered; when the target appears in the image and is located in the central area of ​​the image, the positioning state is entered, and the pan-tilt camera on the fixed-wing unmanned aerial vehicle is controlled to deflect according to the deviation between the center point of the target and the center of the image; after the deflection process, the optical axis of the pan-tilt camera points to the target, and according to the angle between the pan-tilt camera and the fixed-wing unmanned aerial vehicle in the pitch and yaw directions, according to these two angles, the geographical information and altitude information of the fixed-wing unmanned aerial vehicle, the geographical location information of the target relative to the fixed-wing unmanned aerial vehicle is obtained through settlement processing. The method of the present invention has the advantages of simple principle, simple flight mission of the fixed-wing unmanned aerial vehicle, and multiple positioning of outdoor ground targets.

Description

Technical Field

[0001] The invention relates to a fixed-wing unmanned aerial vehicle positioning method belonging to the technical field of fixed-wing unmanned aerial vehicle control, and in particular to a method for a fixed-wing unmanned aerial vehicle to measure and locate the geographical location of a ground target multiple times. Background Art

[0002] In traditional positioning methods, quadcopters often use the onboard gimbal camera combined with image information to locate indoor targets, but it is not suitable for long-term positioning of targets at high altitudes outdoors. Target positioning is still one of the most important functions of fixed-wing UAVs. The target's position in space is calculated by using the target's feature point information combined with the internal and external parameters of the onboard sensor. Since the calibration of parameters is prone to errors and the fixed-wing UAV is in a high-speed motion state, the positioning effect is poor; in addition, the feature point information is independent of the control link, and it is impossible to ensure that the target is always within the field of view of the gimbal camera, making it impossible for fixed-wing UAVs to achieve long-term robust tracking. Summary of the invention

[0003] To solve the above problems, the purpose of the present invention is to provide a method for a fixed-wing UAV to measure and locate the geographical location of a ground target multiple times, and to use its own geographical location information to calculate the longitude and latitude information of the ground target.

[0004] The method of the invention has the advantages of simple principle, simple fixed-wing UAV flight mission, multiple positioning of outdoor ground targets, etc.

[0005] The technical solution of the present invention is:

[0006] 1) The fixed-wing UAV performs the desired route mission and flies in the target area. The fixed-wing UAV maintains the desired route at a constant speed and altitude at the minimum speed. During the flight, the gimbal camera installed on the fixed-wing UAV is controlled to maintain a fixed initial posture relative to the fixed-wing UAV;

[0007] 2) Use the gimbal camera installed on the fixed-wing drone to capture images and monitor in real time:

[0008] If the target does not appear in the image, no processing is performed and the flight continues until the target appears in the image;

[0009] If the target appears in the image and is located in the center area of ​​the image, proceed to the next step;

[0010] If the target appears in the image and is not located in the center of the image, the fixed-wing drone is controlled to enter the adjustment state S t1 , until the target appears in the image and is located in the center area of ​​the image;

[0011] The target being located in the central area of ​​the image is determined by whether the center of mass of the target is located in the central area of ​​the image.

[0012] The image center area is a rectangular area with the image center as the origin, three quarters of the width of the complete image as the width, and three quarters of the height of the complete image as the height.

[0013] 3) When the target appears in the image and is located in the center of the image, the fixed-wing drone is controlled to enter the positioning state S t2 , according to the deviation between the target and the image center, the gimbal camera on the fixed-wing UAV is controlled to deflect based on the deflection strategy and the set fuzzy controller;

[0014] The coordinates of the target center are s, which deviate from the coordinates of the image center s*.

[0015] 4) After the deflection processing according to step 3), the target is located in the center area of ​​the image, and the optical axis of the gimbal camera points to the target. According to the angle between the gimbal camera and the fixed-wing UAV in the pitch and yaw directions, the least squares method is used to obtain the target's geographic location information in combination with the fixed-wing UAV's geographic location information.

[0016] In a specific implementation, a GPS device is used to obtain the geographic location information of the fixed-wing UAV.

[0017] In the step 1), the desired route is composed of straight lines and circular arcs, and the desired route is composed of a broken line consisting of a plurality of waypoints, some of which are pre-set as desired waypoints.

[0018] The position information of the target can be effectively measured in such a desired route.

[0019] In the step 1), the fixed-wing UAV flies horizontally, and the gimbal camera is controlled to tilt downward toward the ground, and an angle difference of 45 degrees is formed between the gimbal camera and the horizontal plane of the fixed-wing UAV.

[0020] The adjustment state S t1 In the present invention, the fixed-wing UAV is controlled to fly only in a circular route, and the fixed-wing UAV is controlled to fly in real time at a yaw rate w according to the direction of the desired target relative to the fixed-wing UAV.

[0021] By entering the adjustment state S t1 It can effectively prevent the target from moving away from the center area of ​​the image.

[0022] The adjustment state S t1 , the fixed-wing UAV flies at a speed v, radius r, and maintains an arc at an altitude h, and does not change the attitude of the gimbal camera relative to the fixed-wing UAV. The yaw rate ω of the fixed-wing UAV is obtained according to the following formula:uav for:

[0023]

[0024] d=L*sinη1

[0025] Where d represents the horizontal distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route, L represents the distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route, η1 represents the component of the desired yaw angle η projected onto the horizontal plane, r represents the radius of the arc route, and v uav represents the speed of the fixed-wing UAV, and h represents the flight altitude of the fixed-wing UAV. Indicates the rate of change of the horizontal distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route.

[0026] Yaw angular rate ω uav It is the angular velocity of the center of the circle around the arc.

[0027] In specific implementation, a Cartesian coordinate system is established with the current position of the fixed-wing UAV as the center point, and the line between the current position and the nearest desired waypoint is decomposed into horizontal and vertical directions at the component η1 angle to obtain the horizontal distance d between the current position and the nearest desired waypoint, which is then processed to obtain the yaw angle rate.

[0028] The positioning state S t2 In the process, the fixed-wing UAV is controlled to adjust the state S t1 The tangent of the arc route in the figure flies at a constant speed at a fixed altitude on a straight route. The deflection speed of the gimbal camera gimbal is obtained according to the following formula, and the gimbal camera gimbal is controlled to deflect relative to the attitude of the fixed-wing drone:

[0029]

[0030] θ=(w x , w y )

[0031] Where θ represents the deflection speed of the gimbal camera, w x It represents the component of the deflection velocity of the gimbal camera in the pitch direction, w y It represents the component of the gimbal's deflection velocity in the yaw direction. is the image Jacobian matrix, λ a represents the fuzzy adjustment gain, s(t) represents the coordinates of the target center of mass in the image at time t, and s * Represents the coordinates of the center of the image.

[0032] Deflection control is to establish the image coordinate system according to the target position s(t) and the image center s* The deflection direction is obtained by the relative position relationship, and the position deviation between the coordinates of the target center of mass and the image center is used to design and control the target using a fuzzy controller, so that the target can quickly converge to the center of the image.

[0033] Deflection control is to obtain the relative relationship between the target position in the image and the image center position after the image coordinate system is established. Since the yaw and pitch movements of the gimbal camera are relatively independent, the yaw and pitch movement directions are determined based on the directionality of the deviations ΔX and ΔY.

[0034] The current gimbal camera posture relative to the fixed-wing drone is recorded as the current posture. The angles in pitch and yaw compared to the initial posture are used to calculate the distance A between the target and the fixed-wing drone in the horizontal direction of the drone's geographic coordinate system by using the following formula:

[0035]

[0036]

[0037] Among them, (x i ,y i ) represents the geographic coordinates of the drone when the same target is measured multiple times at different locations, Δ i is the measurement error when the fixed-wing UAV’s line of sight optical axis points to the target, p i represents the angle between the gimbal camera and the fixed-wing drone in the yaw direction, q i represents the angle between the gimbal camera and the fixed-wing UAV in the pitch direction, i represents the sequence number of the fixed-wing UAV measuring the same target at the i-th geographical location, i=1, 2, 3..., h represents the flight altitude of the fixed-wing UAV;

[0038] When A is not equal to R, it means that the target does not appear in the camera image range of the fixed-wing UAV, and the processing is not performed until the target appears in the camera image range of the fixed-wing UAV.

[0039] When A=R, it is considered that the geographic coordinates of the fixed-wing UAV fall on a circle with the target (X, Y) as the center and a radius of R, where R represents the expected circle radius. The following formula is established and the least squares method is used to solve the target position on the ground (X, Y):

[0040] δ i =(x i -X) 2 +(y i -Y) 2 -R 2

[0041] Among them, δ iIt represents the difference between the square of the distance between the UAV at the i-th geographical location and the target's position on the ground (X, Y) and the square of the radius of the fitting circle;

[0042] Using the least squares method, when δ i When the minimum value is taken, the position of the target on the ground (X, Y) is obtained, and the longitude and latitude are obtained by converting it to the geodetic coordinate system according to the following formula:

[0043]

[0044]

[0045] Among them, L 固定翼无人机 , B 固定翼无人机 are the latitude and longitude of the fixed-wing drone, L 目标 , B 目标 are the latitude and longitude of the target respectively, and RE represents the curvature of the earth.

[0046] In the specific implementation, the same target is measured multiple times at different positions, the optical axis of the gimbal camera is projected to the horizontal direction, and the projection intersects at the target point. The data of multiple measurements are used for input processing, and the least squares method is used for solution processing to obtain the coordinates (X, Y) of the target in the geographic coordinate system of the drone, and finally converted to the geodetic coordinate system to obtain the coordinates of the target (L 目标 , B 目标 ).

[0047] The present invention controls the pan-tilt camera and the fixed-wing UAV respectively according to the rate of change of the image, can perform multiple measurements on ground targets, and uses the least squares method to process data to improve positioning accuracy.

[0048] The present invention utilizes visual servoing and fuzzy control to control the pan-tilt platform, so that the target is always kept in the image center range, and combines the aircraft position parameters and the pan-tilt platform pointing target angle parameters to calculate the longitude and latitude of the target in the earth's geographic coordinate system.

[0049] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0050] The present invention constructs a route task composed of straight lines and circular arcs, simplifies the route task of fixed-wing UAV positioning, and controls the fixed-wing UAV and the gimbal camera separately compared to the positioning heading task of an ideal circle, thereby reducing the control amount in the entire positioning task process and improving the target locking efficiency;

[0051] The present invention uses visual servoing combined with fuzzy control adjustment to quickly control the pan-tilt platform. When the optical axis of the pan-tilt platform camera intersects the target using multiple measurements at different positions, the relative position relationship between the fixed-wing UAV and the target is calculated using the least squares method to calculate the geographical location information of the target, thereby improving the positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a fixed-wing UAV route mission map;

[0053] Figure 2 It is the image partition map of the gimbal camera;

[0054] Figure 3 Schematic diagram for calculating the yaw rate w

[0055] Figure 4 Schematic diagram of target positioning for multiple measurements of optical axis intersection for fixed-wing UAV;

[0056] Figure 5 It is a task flow chart. DETAILED DESCRIPTION

[0057] The following is a detailed description of the method for multiple measurement and positioning of the geographical location of a ground target by a fixed-wing UAV proposed in the present invention in conjunction with the accompanying drawings of the specification.

[0058] like Figure 5 As shown, the embodiments of the present invention and their implementation process are as follows:

[0059] Design and plan a fixed-wing UAV to measure and locate the desired route mission of the ground target multiple times. Figure 1 The route mission is composed of a circular arc tangent to a straight line, which can effectively observe the target information and obtain latitude and longitude information (L 固定翼无人机 , B 固定翼无人机 ) and height information h, the fixed-wing UAV maintains a constant speed and altitude flight at the minimum speed, and the gimbal camera maintains a 45-degree angle difference with the fixed-wing UAV in the pitch direction to search for ground targets. An image coordinate system with an image size of 800*600 pixels collected by the gimbal camera is established, and its image center coordinates p0(x0, y0) = (400, 300), the maximum value of the horizontal axis l is 800, and the maximum value of the vertical axis w is 600.

[0060] In the specific implementation, a system coordinate system of the image coordinate system, the gimbal camera coordinate system, the body coordinate system and the fixed-wing UAV geographic coordinate system is constructed. The gimbal camera image coordinate system takes the upper left vertex of the gimbal camera field of view image as the origin, and its center position is the position of the gimbal camera aiming line p0(x0, y0) = (400, 300), the x-axis and the y-axis are the horizontal axis and the vertical axis respectively. The origin defined by the fixed-wing UAV gimbal coordinate system is located on the optical axis of the gimbal camera with the image center consistent, the y-axis is upward along the optical axis of the gimbal camera, the z-axis is perpendicular to the optical axis of the gimbal camera, and the x-axis is constructed according to the right-hand rule, then the gimbal center and the image center are consistent, then it is considered that the coordinates of the target in the gimbal coordinate system are consistent with the camera image coordinates, expressed as (x0, y0, 0). When the target is locked, the pitch angle is 0° when the gimbal camera is parallel to the fixed-wing UAV nose, the forward tilt is positive, and the backward tilt is negative; when the lens optical axis points to the fixed-wing UAV nose, it is 0°, the clockwise direction is positive, and the counterclockwise direction is negative. The pitch angle of the gimbal lens is α, and the yaw angle is β. At this time, there is a relationship from the gimbal coordinate system g to the fixed-wing UAV body coordinate system b

[0061]

[0062] The coordinates of the target relative to the drone in the drone body coordinate system [X b Y b Z b ]:

[0063]

[0064] Conversion matrix from fixed-wing drone geographic coordinate system n to drone body coordinate system b as follows:

[0065]

[0066] in θ, γ are the heading angle, pitch angle and roll angle of the fixed-wing UAV.

[0067] In the UAV geographic coordinate system, the target coordinates are expressed as:

[0068]

[0069] [XYZ] represents the specific value of the target's coordinates in the geographic coordinate system. represents the transformation matrix from the fixed-wing UAV geographic coordinate system to the body coordinate system, [X b Y b Z b ] represents the position of the target relative to the UAV in the UAV body coordinate system.

[0070] In the specific implementation, the criteria for judging whether the target deviates seriously from the center of the image are as follows: Figure 2 , a rectangular area with a width of 3 / 4l and a length of 3 / 4w is constructed with the center of the image. The shadow area outside these four areas is considered to have a serious image deviation. In the image, I, II, III and IV represent the four quadrants of the image area respectively. The deflection strategy is as follows: when the target is in area I, it means that the expected position of the fixed-wing UAV is in the upper right of the center area; when the target is in area II, it means that the expected position of the fixed-wing UAV is in the upper left of the center area; when the target is in area III, it means that the expected position of the fixed-wing UAV is in the lower left of the center area; when the target is in area IV, it means that the expected position of the fixed-wing UAV is in the lower right of the center area. The target appears in the gimbal camera image, but deviates from the center of the image to a large extent. The expected movement of the fixed-wing UAV is an arc. The fixed-wing UAV deflects toward the expected reference point, and the included angle q on the vertical component between the fixed-wing UAV and the gimbal camera is read at this time. i , and get the radius of the desired circle: The distance between the current position of the fixed-wing drone and the desired waypoint is L, and the desired yaw angle is η. Let η be formed by the three angles η1, η2, and η3, as follows: Figure 3 , according to the following formula to obtain the yaw rate ω of the fixed-wing UAV uav for:

[0071]

[0072] d=L*sinη1

[0073] Where d represents the horizontal distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route, L represents the distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route, η1 represents the component of the desired yaw angle η projected onto the horizontal plane, r represents the radius of the arc route, and v uav represents the speed of the fixed-wing UAV, and h represents the flight altitude of the fixed-wing UAV. Indicates the rate of change of the horizontal distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route.

[0074] In the specific implementation, the whole process enters the positioning state S t2 , the target center appears in the center partition of the image, and the pixel coordinates of the target in the current state are set to s(t), which is different from the expected pixel coordinates in the center of the image s * If there is a deviation, the deviation can be expressed as:

[0075] e(t)=s(t)-s *

[0076] Among them, e(t) represents the deviation between the pixel coordinates of the current state of the target and the coordinates of the center of the image;

[0077] The change speed of the target center point and the change speed of the gimbal in pitch and yaw The transformation relationship is:

[0078]

[0079] in, Indicates the change speed of the gimbal in pitch and yaw, v indicates the change speed of the target center point in the x-axis direction and y-axis direction, L s Indicates the conversion relationship between the change speed of the gimbal in pitch and yaw and the change of the target center point;

[0080] The relationship between the time derivative of the deviation e(t) and the velocity of the center point of the relevant target is:

[0081]

[0082] in, It represents the time derivative of the deviation between the current pixel coordinates of the target and the image center coordinates, L e The conversion relationship between the derivative of the deviation and the change speed of the relevant target center point;

[0083] The speed control scheme of the pan / tilt can be expressed as:

[0084]

[0085] θ=(w x , w y )

[0086] Where θ=(w x , w y ), w x Indicates the speed of controlling the gimbal in the pitch direction, w y Indicates the speed of controlling the gimbal in the yaw direction. Indicated as L e Approximate value of .

[0087] Because in actual situations, L cannot be directly obtained eThe exact value of . Design a gain adjustment controller based on fuzzy rules, mainly considering the changes in the error ||e|| (the difference between the current pixel coordinates of the target center point and the pixel coordinates of the image center) and d||e|| / dt (the differential of the pixel error). There are three fuzzy descriptions of ||e||, d||e|| / dt and λ, namely S (small), M (medium) and B (large). The reasoning method of fuzzy logic is the Mamdani reasoning method, the output function is the Gaussian membership function, the regression type is maximum, and the defuzzification uses the center of gravity of the area (CoA), which is expressed as the output membership function u i (λ a ) is the weighted average of the centroids of i is the weighting factor of the membership function of the i-th rule:

[0088] w i =max((u i ||e|| (||e||),u k (d||e|| / dt))

[0089]

[0090] Among them, (u i ||e|| (||e||),u k (d||e|| / dt) represent the membership functions of error ||e|| and d||e|| / dt, respectively, u i (λ a ) is expressed as the fuzzy output membership function, and the gain λ a Adjusted by fuzzy rules and by restricting all inputs and outputs to obtain a finite λ a e represents the deviation between the current pixel coordinates of the target center point and the pixel coordinates of the image center, ||e|| represents the difference between the current pixel coordinates of the target center point and the pixel coordinates of the image center, and u i (λ a ) represents the error ||e|| under the i-th rule, the gain is λ a The fuzzy output membership function of k represents the output membership function of the differential of the error under the kth rule; d||e|| / dt represents the differential of the pixel error; λ a represents gain; w i represents the weighting factor of the membership function of the i-th rule, and max() represents the maximum value;

[0091] ||e||, d||e|| / dt are the inputs of fuzzy logic and need to be normalized. Through fuzzy control, the pixel error is continuously reduced and finally converges to the desired position. The gimbal camera locks the target, the target appears in the center area, and the angle between the gimbal camera and the fixed-wing drone in yaw and pitch is read.

[0092] In the specific implementation, at different geographical locations, the target appears in the center of the image, the optical axis of the gimbal camera points to the target, the geographical location information of the fixed-wing UAV is obtained, and the current posture of the gimbal camera relative to the fixed-wing UAV is recorded as the current posture. According to the angle between the current posture and the initial posture in the pitch and yaw directions, it is substituted into the following formula:

[0093]

[0094]

[0095] Among them, (x i ,y i ) represents the geographic coordinates of the drone when the same target is measured multiple times at different locations, Δ i is the measurement error when the fixed-wing UAV’s line of sight optical axis points to the target, p i represents the angle between the gimbal camera and the fixed-wing drone in the yaw direction, q i represents the angle between the gimbal camera and the fixed-wing UAV in the pitch direction, i represents the sequence number of the fixed-wing UAV measuring the same target at the i-th geographical location, i=1, 2, 3..., h represents the flight altitude of the fixed-wing UAV;

[0096] When A is not equal to R, it means that the target does not appear in the camera image range of the fixed-wing UAV, and the processing is not performed until the target appears in the camera image range of the fixed-wing UAV.

[0097] When A=R, it is assumed that the geographic coordinates of the fixed-wing UAV fall on a circle with the target (X, Y) as the center and a radius of R, where R represents the expected circle radius, and p i represents the angle between the gimbal and the fixed-wing drone in the yaw direction, q i Indicates the pitch angle between the gimbal and the fixed-wing drone. Δ i is the measurement error when the fixed-wing UAV’s line of sight optical axis points to the target, such as Figure 4 As shown in the figure, the geographical location of the fixed-wing drone at each point (x i ,y i ) into:

[0098] (x i -X) 2 +(y i -Y) 2 =R 2

[0099] δ i =(x i -X) 2 +(y i -Y) 2 -R 2 =x i 2 +y i 2 +ax i +by i +c

[0100] Among them, δ i It represents the difference between the square of the distance between the UAV at the ith geographic location and the target geographic location (X, Y) and the square of the radius of the fitting circle.

[0101] When δ i When the value of approaches 0, the geographical location of the fitted target is more accurate. Let Q(a, b, c) = ∑δ i 2 , derive the three parameters abc, when the following conditions are met:

[0102]

[0103] Fit the value of the target (X, Y) geographic location:

[0104]

[0105] The target coordinates converted into the geodetic coordinate system are expressed as:

[0106]

[0107]

[0108] Among them, L 固定翼无人机 , B 固定翼无人机 are the latitude and longitude of the fixed-wing drone, L 目标 , B 目标 are the latitude and longitude of the target respectively, and RE represents the curvature of the earth.

[0109] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A method for measuring and locating the geographical location of a ground target by a fixed-wing UAV multiple times, characterized in that: The method comprises the following steps: 1) The fixed-wing UAV performs the desired route mission and flies in the target area. The fixed-wing UAV maintains a minimum speed and a constant altitude to fly along the desired route. During the flight, the gimbal camera installed on the fixed-wing UAV is controlled to maintain a fixed attitude relative to the fixed-wing UAV; 2) Use the gimbal camera installed on the fixed-wing drone to capture images and monitor in real time: If the target appears in the image and is located in the center area of ​​the image, proceed to the next step; If the target appears in the image and is not located in the center of the image, the fixed-wing drone is controlled to enter the adjustment state S t1 , until the target appears in the image and is located in the center area of ​​the image; 3) Control the fixed-wing drone to enter the positioning state S t2 , according to the deviation between the target and the center of the image, the gimbal camera on the fixed-wing UAV is controlled to deflect; 4) After the deflection processing according to step 3), the optical axis of the gimbal camera points to the target, and the geographical location information of the target is obtained according to the angle between the gimbal camera and the fixed-wing UAV in the pitch and yaw directions, combined with the geographical location information of the fixed-wing UAV; The adjustment state S t1 , the fixed-wing UAV flies at a speed v, radius r, and maintains an arc at an altitude h, and does not change the attitude of the gimbal camera relative to the fixed-wing UAV. The yaw rate ω of the fixed-wing UAV is obtained according to the following formula uav for: d=L*sinη1 Where d represents the horizontal distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route, L represents the distance between the current position of the fixed-wing UAV and the nearest desired waypoint in the desired route, η1 represents the component of the desired yaw angle η projected onto the horizontal plane, r represents the radius of the arc route, and v uav represents the speed of the fixed-wing UAV, h represents the flight altitude of the fixed-wing UAV, Indicates the rate of change of the horizontal distance between the current position of the fixed-wing drone and the nearest desired waypoint in the desired route; The positioning state S t2 In the process, the fixed-wing UAV is controlled to adjust the state S t1 The tangent of the arc route in the figure flies at a constant speed at a fixed altitude on a straight route. The deflection speed of the gimbal camera gimbal is obtained according to the following formula, and the gimbal camera gimbal is controlled to deflect relative to the attitude of the fixed-wing drone: θ=(w x ,w y ) Where θ represents the deflection speed of the gimbal camera, w x It represents the component of the deflection velocity of the gimbal camera in the pitch direction, w y It represents the component of the gimbal's deflection velocity in the yaw direction. is the image Jacobian matrix, λ a represents the fuzzy adjustment gain, s(t) represents the coordinates of the target center of mass in the image at time t, and s * Represents the coordinates of the center of the image.

2. The method for measuring and locating the geographical location of a ground target by a fixed-wing UAV multiple times according to claim 1 is characterized by: In the step 1), the desired route is composed of straight lines and circular arcs, and the desired route is composed of a broken line consisting of a plurality of waypoints.

3. The method for measuring and locating the geographical location of a ground target by a fixed-wing UAV multiple times according to claim 1 is characterized by: In the step 1), the fixed-wing UAV flies horizontally, and the gimbal camera is controlled to tilt downward toward the ground, and an angle difference of 45 degrees is formed between the gimbal camera and the horizontal plane of the fixed-wing UAV.

4. The method for measuring and locating the geographical location of a ground target by a fixed-wing UAV multiple times according to claim 1 is characterized by: The adjustment state S t1 In the present invention, the fixed-wing UAV is controlled to fly only in a circular route, and the fixed-wing UAV is controlled to fly in real time at a yaw rate w according to the direction of the desired target relative to the fixed-wing UAV.

5. The method for measuring and locating the geographical location of a ground target by a fixed-wing UAV multiple times according to claim 1, characterized in that: The current gimbal camera posture relative to the fixed-wing drone is recorded as the current posture. The angles in pitch and yaw compared to the initial posture are used to calculate the distance A between the target and the fixed-wing drone in the horizontal direction of the drone's geographic coordinate system by using the following formula: Among them, (x i ,y i ) represents the geographic coordinates of the drone when the same target is measured multiple times at different locations, Δ is the measurement error when the fixed-wing drone’s line of sight optical axis points to the target, and p i represents the angle between the gimbal camera and the fixed-wing drone in the yaw direction, q i represents the angle between the gimbal camera and the fixed-wing UAV in the pitch direction, i represents the sequence number of the fixed-wing UAV measuring the same target at the i-th geographical location, i=1,2,3…, h represents the flight altitude of the fixed-wing UAV; When A=R, it is considered that the geographic coordinates of the fixed-wing UAV fall on a circle with the target (X, Y) as the center and a radius of R, where R represents the expected circle radius. The following formula is established and the least squares method is used to solve the target position on the ground (X, Y): δ i (x) i -X) 2 +(and i -AND) 2 -R 2 Among them, δ i It represents the difference between the square of the distance between the UAV at the i-th geographical location and the target's position on the ground (X, Y) and the square of the radius of the fitting circle; Using the least squares method, when δ i When the minimum value is taken, the position of the target on the ground (X, Y) is obtained, and the longitude and latitude are obtained by converting it to the geodetic coordinate system according to the following formula: Among them, L 固定翼无人机 , B 固定翼无人机 are the latitude and longitude of the fixed-wing drone, L 目标 , B 目标 are the latitude and longitude of the target respectively, and RE represents the curvature of the earth.

Images