Method for controlling unmanned aerial vehicle to enter fixed-point hovering in course flight and fixed-wing unmanned aerial vehicle

Abstract

The invention provides a method for controlling unmanned aerial vehicle flight to enter fixed-point hovering and a fixed-wing unmanned aerial vehicle. The control method comprises the steps that the unmanned aerial vehicle enters first-time turning flight at a first fixed roll angle, the flight path angle of the unmanned aerial vehicle is controlled to point to a hovering circle center, and first-time turning is ended when it is judged that a first-time turning ending condition is met; the unmanned aerial vehicle enters linear flight with the first turning end point as the starting point and the circling circle center as the end point, and linear flight is ended when it is judged that linear flight end conditions are met; the unmanned aerial vehicle enters secondary turning flight at a second fixed roll angle, the flight path of the unmanned aerial vehicle is controlled to be adjusted to be tangent to the spiral circle, and secondary turning is ended when it is judged that secondary turning ending conditions are met; and the unmanned aerial vehicle enters circling flight. The control instruction is automatically generated through the fixed-point hovering parameters, fixed-point hovering is achieved, and the problem that a flight route needs to be remanufactured when the unmanned aerial vehicle turns into fixed-point hovering from a set route is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of UAV flight control, and relates to a control method for a UAV to enter a fixed-point hover during route flight, specifically to a control method for a UAV to perform a fixed-point hover around a point outside the route after receiving a fixed-point hover instruction during normal route flight of the UAV, which is particularly applicable to the flight control process of a fixed-wing UAV. Background Art

[0002] Fixed-wing UAVs are widely used in scenarios such as reconnaissance, surveying and mapping, and aerial photography due to their advantages of high flight speed, long cruising time, high ceiling, and large payload. Generally, during the autonomous flight of a UAV along a pre-established route, if it is required for the UAV to hover around a point outside the route at a given radius, a new flight route needs to be remade and uploaded to the flight control computer of the UAV. Such complex operations affect the timeliness of UAV control and bring great inconvenience to ground control personnel.

[0003] Therefore, it is necessary to develop a UAV hovering control method that enables the UAV to automatically control the execution of hovering control after receiving the hovering center coordinates and hovering radius instructions. Summary of the Invention

[0004] Aiming at the technical problem in the prior art that a UAV needs to remake a flight route when transferring from a pre-established route to a fixed-point hover, the present invention provides a control method for a UAV to enter a fixed-point hover during route flight. By the center and radius parameters of the fixed-point hover, control instructions are automatically generated to achieve fixed-point hover, with simple ground control, simple implementation process, and precise trajectory control.

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

[0006] The present invention provides a control method for a UAV to enter a fixed-point hover during route flight, including the following steps:

[0007] The UAV enters the first turning flight at a first fixed bank angle, controls the track angle of the UAV to point to the hovering center, and ends the first turning when it is judged that the first turning end condition is met;

[0008] The UAV enters a straight flight with the end point of the first turning as the starting point and the hovering center as the end point, and ends the straight flight when it is judged that the straight flight end condition is met;

[0009] The UAV enters the second turning flight at a second fixed bank angle, adjusts the track of the UAV to be tangent to the hovering circle, and ends the second turning when it is judged that the second turning end condition is met;

[0010] The UAV enters the hovering flight.

[0011] Further, the calculation method of the actual control first roll angle of the UAV during the first turning flight process is as follows:

[0012] φ pr1 = φ 1 sgn(Δψ 0 )

[0013] where φ 1 is the first fixed roll angle, Δψ 0 is the difference between the direction angle of the line connecting the UAV and the center of the circle at the starting moment and the track angle of the UAV, and sgn() is the sign function.

[0014] Further, the condition for the end of the first turn is that the absolute value of the difference between the direction angle of the line connecting the UAV and the center of the circle at the current moment and the track angle of the UAV is less than or equal to 3° or the time to enter the first turn is greater than or equal to the first turning time.

[0015] Further, the calculation method of the first turning time is as follows:

[0016]

[0017] where φ 1 is the first fixed roll angle, Δψ 0 is the difference between the direction angle of the line connecting the UAV and the center of the circle at the starting moment and the track angle of the UAV, v 01 represents the speed of the UAV at the starting moment of the first turn, and g represents the acceleration due to gravity.

[0018] Further, the calculation method of the actual control second roll angle of the UAV during the straight flight process is as follows:

[0019] φ pr2 = -k dy DY - k dyi ∫(DY)dt

[0020] where k dy represents the UAV lateral deviation proportional control coefficient, DY represents the UAV lateral deviation, ∫(DY)dt represents the integral of the UAV lateral deviation, and k dyi represents the UAV lateral deviation integral control coefficient.

[0021] Further, the condition for the end of the straight flight is that the distance between the UAV and the center of the circle is less than or equal to the early turning distance, and the calculation formula for the early turning distance is as follows:

[0022]

[0023] where R represents the UAV turning radius, v represents the flight speed of the UAV at the current moment, g represents the acceleration due to gravity, and φ 2is the second fixed roll angle.

[0024] Furthermore, the actual control roll angle of the UAV during the second turning flight process is the second fixed roll angle.

[0025] Furthermore, the condition for the end of the second turn is that the difference between the direction of the line connecting the UAV and the center of the circle at the current moment and the track angle of the UAV is less than or equal to 3° from 90°, or the time to enter the second turn is greater than or equal to the second turning time.

[0026] Furthermore, the calculation method of the second turning time is as follows:

[0027]

[0028]

[0029] where v 02 represents the speed of the UAV at the start of the second turn, g represents the acceleration due to gravity, R represents the turning radius of the UAV, g represents the acceleration due to gravity, and φ 2 is the second fixed roll angle.

[0030] Furthermore, the calculation method of the actual control roll angle of the UAV during turning flight is as follows:

[0031]

[0032] where v 03 represents the speed of the UAV when entering turning control, R represents the turning radius of the UAV, g represents the acceleration due to gravity, k dL represents the lateral deviation proportional control coefficient of the UAV, dL represents the lateral deviation of the UAV, and k dLi represents the lateral deviation integral control coefficient of the UAV, and ∫(dL)dt represents the lateral deviation integral of the UAV.

[0033] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the computer program to implement the foregoing control method.

[0034] The present invention also provides a fixed-wing UAV that adopts the foregoing electronic device.

[0035] Advantages of the present invention compared with the prior art:

[0036] The present invention provides a control method for a UAV to enter fixed-point turning during route flight, having the following advantages:

[0037] 1. The ground control is simple. By sending a hovering instruction containing the hovering center point and the hovering radius, the automatic control of the UAV's fixed-point hovering can be achieved.

[0038] 2. The implementation process is simple. There is no need to manually plan the flight route again or upload the flight route again. The hovering process is automatically completed by the flight control computer according to the sent hovering instruction.

[0039] 3. The trajectory control is accurate. During the flight, through the lateral deviation control, the flight trajectories of the straight flight and the hovering flight can be accurately controlled. Description of the Drawings

[0040] The included drawings are used to provide a further understanding of the embodiments of the present invention. They form a part of the specification, are used to illustrate the embodiments of the present invention, and are used to explain the principles of the present invention together with the text description. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic diagram of the control principle for the UAV to enter fixed-point hovering during the flight of the UAV route provided by the specific embodiment of the present invention. Detailed Embodiments

[0042] The following will detail the specific embodiments of the present invention. In the following description, for the purpose of explanation rather than limitation, specific details are set forth to help fully understand the present invention. However, it is obvious to those skilled in the art that the present invention can also be practiced in other embodiments without these specific details.

[0043] It should be noted here that in order to avoid obscuring the present invention due to unnecessary details, only the device structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, and other details less related to the present invention are omitted.

[0044] During the flight of the UAV route, after receiving the instruction to enter fixed-point hovering, it starts to enter the flight process of fixed-point hovering, as Figure 1 shown. The fixed-point hovering instruction should include the longitude and latitude (Lon, Lat) of the UAV hovering center point and the hovering radius R.

[0045] The control method for the UAV to enter fixed-point hovering during the flight of the UAV route is as follows in detail:

[0046] 1. The UAV enters the first turning flight with a fixed roll angle φ 1 and adjusts the UAV's track angle to point to the hovering center point before ending the first turn.

[0047] The turning algorithm is as follows:

[0048] φ pr1 = φ 1 sgn(Δψ 0 )

[0049] End condition for the first turn:

[0050] The absolute value of the difference between the direction angle of the line connecting the UAV and the center of the circle during hovering and the UAV's flight path angle at the current moment is less than or equal to 3° or the time to enter the first turn is greater than or equal to the first turning time. Expressed as:

[0051] |Δψ v | ≤ 3° or

[0052] Where: φ pr1 is the roll angle used during the actual control of the UAV during the first turn.

[0053] Δψ 0 is the difference between the direction angle of the line connecting the UAV and the center of the circle at the starting moment and the UAV's flight path angle, expressed as Δψ 0 = ψ c0 - ψ v0 ψ c0 represents the direction angle of the line connecting the UAV and the center of the circle at the starting moment, and ψ v0 represents the UAV's flight path angle at the starting moment.

[0054] sgn() is the sign function, and its operation rule is expressed as:

[0055]

[0056] Δψ v is the difference between the direction angle of the line connecting the UAV and the center of the circle and the UAV's flight path angle at the current moment, expressed as Δψ v = ψ c - ψ v ψ c represents the direction angle of the line connecting the UAV and the center of the circle at the current moment, and ψ v represents the UAV's flight path angle at the current moment.

[0057] v 01 represents the speed of the UAV at the starting moment of the first turn.

[0058] g represents the acceleration due to gravity.

[0059] 2. After the UAV finishes the first turn, it enters the straight flight mode with the end point of the first turn as the starting point and the center of the circle as the end point, and controls the UAV to fly towards the center of the circle. When the distance between the UAV and the center of the circle is less than or equal to the early turning distance, the UAV ends the straight flight.

[0060] The straight flight algorithm is as follows:

[0061] φ pr2 = -k dy DY - k dyi ∫(DY)dt

[0062] The end condition of straight flight:

[0063] The distance between the UAV and the center of the hovering circle is less than or equal to the advance turning distance, expressed as:

[0064]

[0065] where: k dy represents the lateral deviation proportional control coefficient of the UAV.

[0066] DY represents the lateral deviation of the UAV.

[0067] ∫(DY)dt represents the integral of the lateral deviation of the UAV.

[0068] k dyi represents the integral control coefficient of the lateral deviation of the UAV.

[0069] d represents the distance between the UAV and the center of the hovering circle.

[0070] R represents the hovering radius of the UAV during hovering flight.

[0071] v represents the flight speed of the UAV at the current moment.

[0072] g represents the acceleration due to gravity.

[0073] φ 2 represents the fixed roll angle of the UAV in the second turning section.

[0074] 3. The UAV enters the second turning flight with a fixed roll angle φ 2 and adjusts the UAV's flight path to be tangent to the hovering circle and then ends the second turn.

[0075] The turning algorithm is as follows:

[0076] φ pr3 = φ 2

[0077] The end condition of turning:

[0078] The difference between the direction of the line connecting the UAV and the center of the hovering circle at the current moment and the flight path angle of the UAV and the difference from 90° is less than or equal to 3° or the time to enter the second turn is greater than or equal to the second turning time. Expressed as:

[0079] |Δψ v - 90°| ≤ 3° Or

[0080] Where: φ pr3 is the roll angle used in the actual control of the UAV during the second turn.

[0081] Δψ v is the difference between the direction angle of the line connecting the UAV and the center of the circle and the UAV's track angle at the current moment, expressed as Δψ v = ψ c - ψ v where ψ c represents the direction angle of the line connecting the UAV and the center of the circle at the current moment, and ψ v represents the UAV's track angle at the current moment.

[0082] Δψ 1 is calculated as follows

[0083]

[0084] v 02 represents the speed of the UAV at the start of the second turn.

[0085] g represents the acceleration due to gravity.

[0086] 4. The UAV enters the hovering flight mode.

[0087] Hovering control method:

[0088]

[0089] Where: φ pr4 is the roll angle used in the actual control of the UAV.

[0090] v 03 represents the speed of the UAV when entering the hovering control.

[0091] R represents the hovering radius of the UAV.

[0092] g represents the acceleration due to gravity.

[0093] k dL represents the lateral deviation proportional control coefficient of the UAV.

[0094] dL represents the lateral deviation of the UAV.

[0095] k dLi represents the lateral deviation integral control coefficient of the UAV.

[0096] ∫(dL)dt represents the integral of the lateral deviation of the UAV.

[0097] Features described and / or illustrated above for one embodiment can be used in the same or similar manner in one or more other embodiments, and / or combined with or replace features in other embodiments.

[0098] It should be emphasized that the term "comprising / including" as used herein refers to the presence of features, whole things, steps or components, but does not exclude the presence or addition of one or more other features, whole things, steps, components or combinations thereof.

[0099] Many features and advantages of these embodiments are apparent from this detailed description, so the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. In addition, since many modifications and changes are readily conceivable by those skilled in the art, the embodiments of the present invention are not to be limited to the exact structures and operations illustrated and described, but may cover all suitable modifications and equivalents falling within their scope.

[0100] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0101] The parts not described in detail in the present invention are well-known technologies to those skilled in the art.

Claims

1. A control method for a drone to fly along a route and enter a fixed-point hover, characterized in that, it includes the following steps: The drone enters the first turn flight with a first fixed roll angle, controls the track angle of the drone to point to the center of the hover circle, and ends the first turn when it is determined that the first turn end condition is met; The drone enters a straight flight with the end point of the first turn as the starting point and the center of the hover circle as the end point, and ends the straight flight when it is determined that the straight flight end condition is met; The drone enters the second turn flight with a second fixed roll angle, controls the track of the drone to be tangent to the hover circle, and ends the second turn when it is determined that the second turn end condition is met; The drone enters the hover flight.

2. The control method according to claim 1, characterized in that, The calculation method of the actual controlled first roll angle of the drone during the first turn flight is as follows: φ pr1 = φ 1 sgn(Δψ 0 ) Among them, φ 1 is the first fixed roll angle, Δψ 0 is the difference between the direction angle of the line connecting the UAV and the center of the circle at the starting moment and the track angle of the UAV, and sgn() is the sign function.

3. The control method according to claim 2, characterized in that, The first turn end condition is that the absolute value of the difference between the direction angle of the line connecting the drone and the center of the hover circle at the current moment and the track angle of the drone is less than or equal to 3° or the time to enter the first turn is greater than or equal to the first turn time; The calculation method of the first turn time is as follows: Among them, φ 1 is the first fixed roll angle, Δψ 0 is the difference between the direction angle of the line connecting the UAV and the center of the circle at the starting moment and the track angle of the UAV, v 01 represents the speed of the UAV at the starting moment of the first turn, and g represents the acceleration due to gravity.

4. The control method according to claim 1, characterized in that, The calculation method of the actual controlled second roll angle of the drone during the straight flight is as follows: φ pr2 = -k dy DY - k dyi ∫(DY)dt Among them, k dy represents the lateral deviation proportional control coefficient of the UAV, DY represents the lateral deviation of the UAV, ∫(DY)dt represents the integral of the lateral deviation of the UAV, and k dyi represents the integral control coefficient of the lateral deviation of the UAV.

5. The control method according to claim 4, characterized in that, The straight flight end condition is that the distance between the drone and the center of the hover circle is less than or equal to the early turn distance, and the calculation formula of the early turn distance is as follows: where R represents the hovering radius of the UAV, v represents the flight speed of the UAV at the current moment, g represents the acceleration due to gravity, and φ 2 is the second fixed roll angle.

6. The control method according to claim 1, characterized in that, The actual controlled roll angle of the drone during the second turn flight is the second fixed roll angle.

7. The control method according to claim 6, characterized in that, The second turn end condition is that the difference between the direction of the line connecting the drone and the center of the hover circle at the current moment and the track angle of the drone and 90° is less than or equal to 3° or the time to enter the second turn is greater than or equal to the second turn time; The calculation method of the second turn time is: Among them, v 02 represents the speed at the starting moment of the second turn of the UAV, g represents the acceleration due to gravity, R represents the hovering radius of the UAV, g represents the acceleration due to gravity, and φ 2 is the second fixed roll angle..

8. The control method according to claim 1, characterized in that, The calculation method of the actual controlled roll angle of the drone during the hover flight is as follows: Among them, v 03 represents the speed of the UAV when entering the hovering control, R represents the hovering radius of the UAV, g represents the acceleration due to gravity, k dL represents the lateral deviation proportional control coefficient of the UAV, dL represents the lateral deviation of the UAV, k dLi represents the lateral deviation integral control coefficient of the UAV, and ∫(dL)dt represents the lateral deviation integral of the UAV.

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

10. A fixed-wing drone, characterized in that, it adopts the electronic device described in claim 9.

Images