Calculation method of velocity vector

Abstract

The invention provides a velocity vector calculation method, which comprises the following steps of: superposing a velocity vector mark on a front downward-looking image, and calculating the real-time change of the position of the vector mark on the front downward-looking image; the method comprises the following steps: calculating a velocity vector horizontal direction, calculating a horizontal velocity direction according to east and north velocities of an aircraft, determining a final horizontal deflection angle by taking a difference between the horizontal velocity direction and a course angle as a horizontal deflection angle, and determining a velocity vector horizontal direction stay position according to the final horizontal deflection angle; calculating the vertical direction of the velocity vector, calculating a vertical velocity angle according to the sky velocity and the ground velocity of the aircraft, taking the difference between the pitch angle and the mounting angle of the aircraft as the sight angle of the front downward-looking camera, taking the difference between the vertical velocity angle and the sight angle as the vertical sight angle of the aircraft, and determining the stop position of the velocity vector in the vertical direction according to the vertical sight angle. The real running direction of the aircraft is represented through the vector marks, and the problem that visual deviation exists between the head direction and the flight direction when the aircraft flies in the air can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of manned / unmanned aircraft, and specifically relates to a method for calculating a velocity vector, and in particular to an avionics system of a manned aircraft and a ground station system of an unmanned aircraft, as well as ground take-off and landing software for a fixed-wing unmanned aerial vehicle. Background Art

[0002] For medium and large fixed-wing drones, a front downward camera is usually installed to shoot videos from the front and bottom of the drone, and transmit the videos to the ground station via a wireless link for display, to assist the drone operator in driving the drone. The most important function of the front downward camera is to assist the drone in taking off and landing. When installed, it is generally parallel to the direction of the fuselage in the horizontal direction and tilted downward at a certain angle in the pitch direction. By selecting the camera lens and CMOS sensor, the field of view of the front downward camera can be effectively configured, which can more accurately display images and videos in the direction of the drone's nose.

[0003] However, when a drone is flying in the air, its flight attitude will be affected by the crosswind. The phenomenon manifested is that the direction the nose points to deviates from the direction the aircraft is actually flying. This creates an illusion that the center direction of the front downward image is the direction of the aircraft's flight route. Therefore, it is necessary to design a method for processing the front downward image of a drone to mark the flight direction of the drone and assist the drone operator in determining the aircraft's route. Summary of the invention

[0004] In order to solve the technical problem that there is an angular deviation between the flight route direction and the nose pointing of a fixed-wing UAV during flight, the present invention provides a method for calculating a velocity vector, which superimposes a velocity vector mark on the front downward image of the UAV, calculates the real-time change of the vector mark position on the front downward image, indicates the flight heading of the UAV, and assists the UAV operator in determining the aircraft's route.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] The present invention provides a method for calculating a velocity vector, comprising the following steps:

[0007] Calculate the horizontal direction of the velocity vector:

[0008] Calculate the ground speed of the aircraft according to a fixed period, and determine whether the ground speed is less than a first threshold. If so, the velocity vector is at the horizontal center of the image. Otherwise, calculate the horizontal velocity direction according to the eastward velocity and the northward velocity of the aircraft.

[0009] The difference between the horizontal velocity direction and the heading angle is calculated as the horizontal deflection angle;

[0010] According to the horizontal deflection angle value, calculate the final horizontal deflection angle;

[0011] Determine the horizontal stop position of the velocity vector according to the final horizontal deflection angle;

[0012] Calculate the vertical direction of the velocity vector:

[0013] Calculate the ground speed of the aircraft according to a fixed period, and determine whether the ground speed is less than a first threshold. If so, the velocity vector is at the vertical center of the image; otherwise, calculate the vertical velocity angle according to the celestial velocity and the ground speed of the aircraft;

[0014] Calculate the difference between the aircraft pitch angle and the installation angle as the sight angle of the front downward camera;

[0015] The difference between the vertical velocity angle and the sight angle is calculated as the vertical sight angle of the aircraft;

[0016] The vertical position of the velocity vector is determined according to the vertical sight angle.

[0017] Furthermore, the velocity vector calculation method further includes an initialization step, wherein the velocity vector marker is initialized to be located at the horizontal center and the vertical center of the front downward-viewing image and remains stationary.

[0018] Furthermore, the fixed period is a refresh period of the front downward-viewing image.

[0019] Furthermore, the first threshold is the minimum flight speed allowed for the aircraft to remain airborne.

[0020] Furthermore, the method for calculating the horizontal velocity direction according to the eastward velocity and northward velocity of the aircraft is as follows:

[0021] If the aircraft's northward velocity is 0 and its eastward velocity is positive, the horizontal velocity direction is 90°;

[0022] If the aircraft's northward velocity is 0 and its eastward velocity is negative, the horizontal velocity direction is 270°;

[0023] If north velocity > 0 and east velocity ≥ 0, then horizontal velocity direction = arctan (east velocity / north velocity);

[0024] If north velocity > 0 and east velocity < 0, then horizontal velocity direction = 360° + arctan (east velocity / north velocity);

[0025] If north velocity < 0 and east velocity ≥ 0, then horizontal velocity direction = 180° + arctan (east velocity / north velocity);

[0026] If north velocity < 0 and east velocity < 0, then horizontal velocity direction = 180° + arctan (east velocity / north velocity).

[0027] Furthermore, the method for calculating the final horizontal deflection angle according to the horizontal deflection angle value is as follows:

[0028] If -180°<horizontal deflection angle<180°, the final deflection angle = horizontal deflection angle;

[0029] If the horizontal deflection angle is ≥180°, the final deflection angle = horizontal deflection angle - 360°;

[0030] If the horizontal deflection angle is ≤-180°, the final deflection angle = horizontal deflection angle + 360°.

[0031] Furthermore, the vertical velocity angle=arctan(vertical velocity / ground velocity).

[0032] Furthermore, the method for determining the horizontal position of the velocity vector according to the final horizontal deflection angle is as follows:

[0033] If the final horizontal deflection angle is >X°, where X represents half of the horizontal field of view of the front downward camera, the velocity vector stays at the rightmost edge of the image;

[0034] If the final horizontal deflection angle is <-X°, the velocity vector stays at the leftmost edge of the image;

[0035] If -X°≤final horizontal deflection angle≤X°, the velocity vector moves according to the horizontal deflection ratio, horizontal deflection ratio=final horizontal deflection angle / X*100%;

[0036] The method for determining the vertical position of the velocity vector according to the vertical sight angle is:

[0037] If the vertical sight angle > Y°, where Y represents half of the vertical field of view of the forward-looking camera, the velocity vector stays at the uppermost edge of the image;

[0038] If the vertical sight angle is <-Y°, the velocity vector stays at the bottom edge of the image;

[0039] If -Y°≤vertical sight angle≤Y°, the velocity vector moves according to the vertical deflection ratio, where the vertical deflection ratio=vertical sight angle / Y*100%.

[0040] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the aforementioned calculation method.

[0041] The present invention further provides a fixed-wing UAV, which adopts the electronic equipment.

[0042] The beneficial effects of the present invention compared with the prior art are as follows:

[0043] 1. When an aircraft is flying in the air, its flight attitude will be affected by the crosswind, resulting in a deviation between the direction the nose is pointing and the direction the aircraft is actually flying. The image of the front downward camera installed at the nose position is an important reference for the pilot to judge the flight direction, which will give the pilot an illusion due to the influence of the lateral deviation. The present invention provides a method for indicating the true running direction of an aircraft by means of a vector mark, which can solve the problem of visual deviation between the nose direction and the flight direction when the aircraft is flying in the air.

[0044] 2. After the design is completed according to the present invention, the vector marking symbol will be superimposed on the front downward image for display, which can truly display the information such as the runway, clouds, obstacles, etc. in the direction of the aircraft's operation, providing an important reference for the pilot's flight decision.

[0045] 3. The velocity vector calculation method involved in the present invention uses input parameters that are all from common navigation equipment of aircraft, including satellite navigation equipment and inertial navigation equipment. There is no need to add additional sensors to the aircraft, and there is no increase in cost or burden.

[0046] 4. The present invention introduces limiting conditions in the calculation. When the flight speed is less than the stall speed, the aircraft is considered to be gliding on the ground and there is no need to solve the velocity vector. When the crosswind is too strong, causing the velocity vector mark to exceed the field of view of the front downward image, this method will limit the display boundary of the vector mark. This can effectively improve the practicality and feasibility of the present invention.

[0047] 5. When calculating the vertical display position, the present invention fully considers the installation angle error of the front downward camera and introduces the error into the calculation method, which can effectively improve the display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 A schematic diagram of displaying a velocity vector mark in a front downward image provided by a specific embodiment of the present invention. DETAILED DESCRIPTION

[0050] Specific embodiments of the present invention are described in detail below. In the following description, for the purpose of explanation and not limitation, specific details are set forth to help fully understand the present invention. However, it will be apparent to those skilled in the art that the present invention may also be practiced in other embodiments that depart from these specific details.

[0051] It should be noted that in order to avoid obscuring the present invention due to unnecessary details, only the device structure and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0052] In view of the problem that there is an angle deviation between the flight route direction and the nose direction of a fixed-wing UAV during flight, the present invention provides a calculation and display method for accurately indicating the flight route direction using a velocity vector mark. The calculation method of the velocity vector has the final effect of displaying the vector mark at the verified position of a two-dimensional image screen, and the following will be calculated separately according to the display position in the horizontal direction and the display position in the vertical direction.

[0053] Calculation and display method in the horizontal direction:

[0054] Step 1: In the initial stage, the velocity vector marker is located at the horizontal center of the front downward image and remains stationary.

[0055] Step 2: According to the fixed period T0 (T0 represents the refresh period of the front downward image), determine whether the ground speed of the aircraft (measured by the satellite navigation system installed on the aircraft, or calculated by the square root of the sum of the eastward speed and the northward speed) is less than v1 (v1 is the minimum flight speed allowed for the aircraft to remain in the air):

[0056] If it is less than, the velocity vector is at the horizontal center of the image screen;

[0057] If it is not less than, go to the next step;

[0058] Step 3: Determine whether the north velocity is 0 and calculate the horizontal velocity direction. The north velocity is measured by the satellite navigation system installed on the aircraft. It is a signed number with positive values ​​for the north and negative values ​​for the south. The east velocity is measured by the satellite navigation system installed on the aircraft. It is a signed number with positive values ​​for the east and negative values ​​for the west.

[0059] If the north speed is 0, the following judgment is made:

[0060] If the eastward velocity is positive, the horizontal velocity direction = 90°; go to step 5;

[0061] If the eastward velocity is negative, the horizontal velocity direction = 270°; go to step 5;

[0062] If it is not 0, go to step 4;

[0063] Step 4: Calculate the horizontal velocity direction using the values ​​of the east velocity and north velocity. The east velocity is measured by the satellite navigation system installed on the aircraft:

[0064] If north velocity > 0 and east velocity ≥ 0, then horizontal velocity direction = arctan (east velocity / north velocity);

[0065] If north velocity > 0 and east velocity < 0, then horizontal velocity direction = 360° + arctan (east velocity / north velocity);

[0066] If north velocity < 0 and east velocity ≥ 0, then horizontal velocity direction = 180° + arctan (east velocity / north velocity);

[0067] If north velocity < 0 and east velocity < 0, then horizontal velocity direction = 180° + arctan (east velocity / north velocity);

[0068] Step 5: Calculate the horizontal deflection angle = horizontal velocity direction - heading angle. The heading angle is generally obtained through an inertial measurement device installed on the aircraft. The heading angle range is 0° to 360°.

[0069] Step 6: Calculate the final horizontal deflection angle according to the horizontal deflection angle value. The calculation method is as follows:

[0070] If -180°<horizontal deflection angle<180°, the final deflection angle = horizontal deflection angle;

[0071] If the horizontal deflection angle is ≥180°, the final deflection angle = horizontal deflection angle - 360°;

[0072] If the horizontal deflection angle is ≤-180°, the final deflection angle = horizontal deflection angle + 360°;

[0073] Step 7: Calculate the horizontal display position of the velocity vector based on the final horizontal deflection angle value:

[0074] If the final horizontal deflection angle > X° (X represents half of the horizontal field of view of the front downward camera), the velocity vector stays at the rightmost edge of the front downward image (note that it is not the screen).

[0075] If the final horizontal deflection angle is <-X°, the velocity vector stays at the leftmost edge of the front downward view (note that it is not the screen).

[0076] If -X°≤final horizontal deflection angle≤X°, the velocity vector stop position is calculated as follows:

[0077] The center of the previous downward view is the coordinate zero point, the left is negative, the right is positive, and the position of the velocity vector is moved according to the horizontal deflection ratio. Horizontal deflection ratio = final horizontal deflection angle / X*100%.

[0078] Step 8: Refresh the above calculations at the fixed period T0 described in step 2 and refresh the velocity vector position.

[0079] Vertical display method

[0080] Step 9: In the initial stage, the velocity vector marker is located at the vertical center of the front downward image and remains stationary.

[0081] Step 10: According to the fixed period T0 (T0 represents the refresh period of the front downward image), determine whether the ground speed of the aircraft (measured by the satellite navigation system installed on the aircraft, or calculated by the square root of the sum of the eastward speed and the northward speed) is less than v1 (v1 is the minimum flight speed allowed for the aircraft to remain in the air):

[0082] If it is less than, the velocity vector remains at the vertical center of the frame;

[0083] If it is not less than, go to the next step;

[0084] Step 11: Calculate the vertical velocity angle based on the celestial velocity and ground velocity, that is, the angle between the UAV's running direction and the horizontal direction. The celestial velocity is measured and obtained by the satellite navigation system installed on the aircraft:

[0085] Vertical velocity angle = arctan (celestial velocity / ground velocity) (note that celestial velocity is a signed number)

[0086] Step 12: Calculate the sight angle of the front downward camera, that is, the angle between the camera's sight center and the horizontal plane:

[0087] Sight angle = drone pitch angle - installation angle (installation angle refers to the angle at which the front downward camera is tilted downward compared to the horizontal direction when installed)

[0088] Step 13: Calculate the vertical sight angle, which is the vertical angle between the drone's running direction and the camera's sight line:

[0089] Vertical sight angle = vertical velocity angle - sight angle

[0090] Step 14: Calculate the vertical position of the velocity vector based on the vertical sight angle value

[0091] If the vertical sight angle>Y° (Y represents half of the vertical field of view of the front-down camera), the velocity vector stays at the uppermost edge of the front-down image (note that it is not the screen).

[0092] If the vertical sight angle is <-Y°, the velocity vector stays at the bottom edge of the front downward viewing screen (note that it is not the screen).

[0093] If -Y°≤vertical sight angle≤Y°, the velocity vector stop position is calculated as follows:

[0094] The previous downward-looking screen is the coordinate zero point, downward is negative, upward is positive, and the position of the velocity vector is moved according to the vertical deflection ratio. Vertical deflection ratio = vertical sight angle / Y*100%.

[0095] Features described and / or illustrated above for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or used in place of features in other embodiments.

[0096] It should be emphasized that the term include / comprising when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0097] The many features and advantages of these embodiments are apparent from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended that the embodiments of the invention be limited to the exact construction and operation illustrated and described, but rather all suitable modifications and equivalents falling within the scope thereof are intended to be covered.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0099] Parts of the present invention that are not described in detail are well known to those skilled in the art.

Claims

1. A method for calculating velocity vector, It is characterized in that The steps include: Calculate the horizontal direction of the velocity vector: Calculate the ground speed of the aircraft according to a fixed period, and determine whether the ground speed is less than a first threshold. If so, the velocity vector is at the horizontal center of the image. Otherwise, calculate the horizontal velocity direction according to the eastward velocity and the northward velocity of the aircraft. The difference between the horizontal velocity direction and the heading angle is calculated as the horizontal deflection angle; According to the horizontal deflection angle value, calculate the final horizontal deflection angle; Determine the horizontal stop position of the velocity vector according to the final horizontal deflection angle; Calculate the vertical direction of the velocity vector: Calculate the ground speed of the aircraft according to a fixed period, and determine whether the ground speed is less than a first threshold. If so, the velocity vector is at the vertical center of the image; otherwise, calculate the vertical velocity angle according to the celestial velocity and the ground speed of the aircraft; Calculate the difference between the aircraft pitch angle and the installation angle as the sight angle of the front downward camera; The difference between the vertical velocity angle and the sight angle is calculated as the vertical sight angle of the aircraft; The vertical position of the velocity vector is determined according to the vertical sight angle.

2. The method for calculating the velocity vector according to claim 1, It is characterized in that The velocity vector calculation method also includes an initialization step, wherein the velocity vector marker is located at the horizontal center and the vertical center of the front downward-viewing image and remains stationary.

3. The method for calculating the velocity vector according to claim 1, It is characterized in that The fixed period is a refresh period of the front downward-viewing image.

4. The method for calculating the velocity vector according to claim 1, It is characterized in that The first threshold is the minimum flight speed allowed for the aircraft to remain airborne.

5. The method for calculating the velocity vector according to claim 1, It is characterized in that The method for calculating the horizontal velocity direction according to the eastward velocity and northward velocity of the aircraft is as follows: If the aircraft's northward velocity is 0 and its eastward velocity is positive, the horizontal velocity direction is 90°; If the aircraft's northward velocity is 0 and its eastward velocity is negative, the horizontal velocity direction is 270°; If north velocity > 0 and east velocity ≥ 0, then horizontal velocity direction = arctan (east velocity / north velocity); If north velocity > 0 and east velocity < 0, then horizontal velocity direction = 360° + arctan (east velocity / north velocity); If north velocity < 0 and east velocity ≥ 0, then horizontal velocity direction = 180° + arctan (east velocity / north velocity); If north velocity < 0 and east velocity < 0, then horizontal velocity direction = 180° + arctan (east velocity / north velocity).

6. The method for calculating the velocity vector according to claim 1, It is characterized in that The method for calculating the final horizontal deflection angle according to the horizontal deflection angle value is as follows: If -180°<horizontal deflection angle<180°, the final deflection angle = horizontal deflection angle; If the horizontal deflection angle is ≥180°, the final deflection angle = horizontal deflection angle - 360°; If the horizontal deflection angle is ≤-180°, the final deflection angle = horizontal deflection angle + 360°.

7. The method for calculating the velocity vector according to claim 1, It is characterized in that The vertical velocity angle=arctan(celestial velocity / ground velocity).

8. The method for calculating the velocity vector according to claim 1, It is characterized in that The method for determining the horizontal position of the velocity vector according to the final horizontal deflection angle is as follows: If the final horizontal deflection angle is >X°, where X represents half of the horizontal field of view of the front downward camera, the velocity vector stays at the rightmost edge of the image; If the final horizontal deflection angle is <-X°, the velocity vector stays at the leftmost edge of the image; If -X°≤final horizontal deflection angle≤X°, the velocity vector moves according to the horizontal deflection ratio, horizontal deflection ratio=final horizontal deflection angle / X*100%; The method for determining the vertical position of the velocity vector according to the vertical sight angle is: If the vertical sight angle > Y°, where Y represents half of the vertical field of view of the forward-looking camera, the velocity vector stays at the uppermost edge of the image; If the vertical sight angle is <-Y°, the velocity vector stays at the bottom edge of the image; If -Y°≤vertical sight angle≤Y°, the velocity vector moves according to the vertical deflection ratio, where the vertical deflection ratio=vertical sight angle / Y*100%.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, It is characterized in that The processor executes the computer program to implement the computing method described in any one of claims 1 to 8.

10. A fixed-wing UAV, It is characterized in that An electronic device according to claim 9 is used.

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