Autonomous landing lateral course control method of low-speed fixed-wing unmanned aerial vehicle, electronic equipment and medium

Abstract

The invention discloses an autonomous landing lateral course control method of a low-speed fixed-wing unmanned aerial vehicle, electronic equipment and a medium. The method comprises the following steps: determining an approach and landing process of an air route, including approach of a fifth edge, glide, leveling, grounding and skating after landing; aiming at the approaching and gliding process of the fifth side, determining first transverse control and first course control through a course method; determining second transverse control and second course control through a sideslip method according to the processes of leveling, grounding and skating after landing; and determining motor rotating speed control aiming at a skating process after landing. According to the method, a starting point of a leveling stage is taken as a boundary, a heading method is mainly adopted before leveling, a sideslip method is mainly adopted after leveling, and meanwhile, power configuration of the low-speed fixed-wing unmanned aerial vehicle is fully utilized for auxiliary control after leveling.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicle (UAV) flight control, and more specifically, to an autonomous landing lateral heading control method, electronic equipment, and medium for a low-speed fixed-wing UAV. Background Art

[0002] During an autonomous descent and landing, a drone must track altitude commands longitudinally and align its longitudinal axis with the runway centerline. Therefore, altitude tracking and track control are crucial during the descent and landing process. The flight approach and landing process can generally be divided into five steps: final approach, descent, flare, touchdown, and post-landing roll.

[0003] In the absence of crosswinds, i.e., wind drift, during approach and landing, the longitudinal axis of the drone should be aligned with the runway centerline throughout the entire process. However, in most cases, crosswinds exist in the runway landing area, and additional steps are required to eliminate the effects of wind drift.

[0004] The most common methods for approaching and landing in crosswind conditions are the heading method and the sideslip method. The heading method aligns the aircraft's speed and heading with the runway centerline. This is achieved by tilting the drone's nose toward the crosswind at a certain angle, so that the component of the drone's airspeed perpendicular to the runway centerline cancels out the crosswind. The sideslip method aligns the aircraft's heading with the runway centerline, tilting the aircraft toward the crosswind at a certain angle by adjusting the ailerons. To prevent a turn, counter-rudder is applied to keep the drone's longitudinal axis aligned with the runway.

[0005] Low-speed fixed-wing drones typically feature a high lift-to-drag ratio, low wing loading, and low flight speed. During approach and landing, using the sideslip method requires the aircraft to maintain a certain bank angle. This poses a significant risk for lightweight drones, easily causing one wingtip to touch the ground first during touchdown. Furthermore, with limited rudder aerodynamic efficiency, there is a risk of saturation of the rudder required to control turns. Using the heading method, these drones exhibit low flight speeds, and even moderate crosswinds can cause the speed heading to deviate from the nose direction by a certain angle. Furthermore, if this method is maintained throughout the landing process, the yaw angle between the nose direction and the direction of motion at touchdown will result in severe side loads on the landing gear and main wheels. Even if a successful landing is achieved using the heading method, the nose will be pointing away from the runway centerline. During the post-landing rollout, as speed decreases, the rudder's effectiveness in correcting the deviation gradually decreases, creating the risk of the drone's sideways deviation continuing to increase, or even running off the runway.

[0006] Therefore, it is necessary to develop an autonomous landing lateral heading control method, electronic equipment and medium for a low-speed fixed-wing UAV.

[0007] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Summary of the Invention

[0008] The present invention proposes a method, electronic equipment and medium for autonomous landing lateral heading control of a low-speed fixed-wing unmanned aerial vehicle. Taking the starting point of the leveling phase as the boundary, the heading method is mainly adopted before leveling, and the sideslip method is mainly adopted after leveling. At the same time, after leveling, the power configuration of the low-speed fixed-wing unmanned aerial vehicle is fully utilized for auxiliary control.

[0009] In a first aspect, an embodiment of the present disclosure provides a method for autonomous landing lateral heading control of a low-speed fixed-wing UAV, comprising:

[0010] Determine the route approach and landing process, including final approach, descent, level off, touchdown and after-landing roll;

[0011] For the final approach and the glide path, determining a first lateral control and a first heading control by a heading method;

[0012] During the leveling, the touchdown, and the post-landing roll, determining a second lateral control and a second heading control by a sideslip method;

[0013] For the post-landing roll process, motor speed control is determined.

[0014] Preferably, the first lateral control is:

[0015]

[0016] in, is the first lateral control instruction, that is, the aileron instruction, ω x is the roll angular rate, φ is the roll angle, φ c is the roll angle command, is the gain coefficient of the aileron to the roll angular rate, is the gain coefficient of the aileron to the roll angle.

[0017] Preferably, the first heading control is:

[0018]

[0019] in, is the first heading control instruction, that is, the rudder instruction, ω y is the yaw rate, ψ v is the speed heading, ψ c is the runway heading angle command, dZ is the lateral deviation of the UAV relative to the runway centerline and its extension line, is the gain coefficient of the rudder to the yaw rate, is the gain coefficient of the rudder to the yaw angle, is the gain coefficient of the rudder contralateral offset.

[0020] Preferably, the second lateral control is:

[0021]

[0022] in, It is the second lateral control instruction.

[0023] Preferably, the second heading control is:

[0024]

[0025] in, It is the second heading control instruction.

[0026] Preferably, determining the motor speed control includes:

[0027] Calculate the motor speed adjustment amount;

[0028] An instruction for controlling the motor speed is determined according to the motor speed adjustment amount.

[0029] Preferably, the motor speed adjustment amount Δn is:

[0030]

[0031] Among them, Δn is the motor speed adjustment amount.

[0032] Preferably, the motor speed control instruction is:

[0033] n=n t +Δn.

[0034] In a second aspect, an embodiment of the present disclosure further provides an electronic device, the electronic device comprising:

[0035] a memory storing executable instructions;

[0036] A processor runs the executable instructions in the memory to implement the autonomous landing lateral heading control method of the low-speed fixed-wing UAV.

[0037] In a third aspect, an embodiment of the present disclosure further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the autonomous landing lateral heading control method of the low-speed fixed-wing UAV.

[0038] Its beneficial effects are:

[0039] (1) During the final approach and descent phase, the lateral heading is controlled using the commonly used heading method to maintain stable track control and attitude control capabilities. At the same time, for low-speed fixed-wing UAVs, this method can effectively reduce the sideslip angle of the UAV during flight and improve the safety of landing flight.

[0040] (2) During the leveling phase and the subsequent process, the lateral heading is controlled by the sideslip method. Before landing, the longitudinal axis of the UAV is adjusted to be in the same direction as the runway, which is beneficial to reducing the lateral load impact on the landing gear.

[0041] (3) During the touchdown and post-landing roll phase, the lateral heading is still controlled by the sideslip method to keep the longitudinal axis of the UAV aligned with the runway centerline and the lateral offset as small as possible. At the same time, the differential control of the symmetrically distributed propulsion motors is used to compensate for the reduction in rudder efficiency, further improving the UAV's lateral heading control capability during the ground roll deceleration phase.

[0042] (4) During the autonomous gliding landing process, according to the flight characteristics of low-speed fixed-wing UAVs and the requirements of each stage, the alternating fusion method of "heading method" + "sideslip method" + "motor differential control" is adopted to effectively control the compromise and safety of yaw angle, lateral offset, wings and landing gear, etc., and improve the control efficiency and safety level in the process.

[0043] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0045] Figure 1 A flowchart showing the steps of a method for autonomous landing lateral heading control of a low-speed fixed-wing UAV according to an embodiment of the present invention is shown.

[0046] Figure 2 A schematic diagram illustrating five stages and trajectories of autonomous landing of a UAV according to an embodiment of the present invention is shown.

[0047] Figure 3 A flow chart of lateral heading control for autonomous landing of a low-speed fixed-wing UAV according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0049] Figure 1 A flowchart showing the steps of a method for autonomous landing lateral heading control of a low-speed fixed-wing UAV according to an embodiment of the present invention is shown.

[0050] like Figure 1 As shown, the autonomous landing lateral heading control method of the low-speed fixed-wing UAV includes:

[0051] Step 101, determining the route approach and landing process, including final approach, descent, leveling off, touchdown, and post-landing roll;

[0052] Step 102: Determine a first lateral control and a first heading control by using a heading method during the final approach and descent process.

[0053] Step 103, determining a second lateral control and a second heading control by a sideslip method for the process of leveling, touchdown, and post-landing roll;

[0054] Step 104: Determine the motor speed control for the rolling process after landing.

[0055] In one example, the first lateral control is:

[0056]

[0057] in, is the first lateral control instruction, that is, the aileron instruction, ω x is the roll angular rate, φ is the roll angle, φ c is the roll angle command, is the gain coefficient of the aileron to the roll angular rate, is the gain coefficient of the aileron to the roll angle.

[0058] In one example, the first heading control is:

[0059]

[0060] in, is the first heading control instruction, that is, the rudder instruction, ω y is the yaw rate, ψ v is the speed heading, ψ c is the runway heading angle command, dZ is the lateral deviation of the UAV relative to the runway centerline and its extension line, is the gain coefficient of the rudder to the yaw rate, is the gain coefficient of the rudder to the yaw angle, is the gain coefficient of the rudder contralateral offset.

[0061] In one example, the second lateral control is:

[0062]

[0063] in, It is the second lateral control instruction.

[0064] In one example, the second heading control is:

[0065]

[0066] in, It is the second heading control instruction.

[0067] In one example, determining motor speed control includes:

[0068] Calculate the motor speed adjustment;

[0069] The motor speed control instruction is determined according to the motor speed adjustment amount.

[0070] In one example, the motor speed adjustment value Δn is:

[0071]

[0072] Among them, Δn is the motor speed adjustment amount.

[0073] In an example, the motor speed control command is:

[0074] n=n t +Δn.

[0075] Specifically, determine the route approach and landing process, including final approach, descent, level off, touchdown and post-landing roll.

[0076] During the final approach and descent phase, the lateral heading is controlled using the heading method to maintain stable track control and attitude control. The lateral heading control structure is:

[0077]

[0078] in, is the aileron command, ω x is the roll angular rate, φ is the roll angle, φ c is the roll angle command, is the gain coefficient of the aileron to the roll angular rate, is the gain coefficient of the aileron to the roll angle; is the rudder command, ωy is the yaw rate, ψ v is the speed heading, ψ c is the runway heading angle command, dZ is the lateral deviation of the UAV relative to the runway centerline and its extension line, is the gain coefficient of the rudder to the yaw rate, is the gain coefficient of the rudder to the yaw angle, is the gain coefficient of the rudder contralateral offset, where the heading angle command ψ c is the runway heading angle value.

[0079] Considering the limited actual rudder output, it is necessary to set maximum limits on the generation of the three rudder commands. For electric propulsion drones, the propulsion motors appear in pairs and are symmetrically distributed. In this case, all motors maintain the same speed.

[0080] During the leveling, touchdown and post-landing roll phases, the lateral heading is controlled by the sideslip method to maintain stable track control capability while avoiding excessive lateral loads on the landing gear during the touchdown process.

[0081] At this time, the second lateral control structure is:

[0082]

[0083] in, is the second lateral control instruction, is the gain coefficient of the aileron integral term for the roll angle. c Reasonable limits should be set to avoid large rolls causing the wingtips to touch the ground, which is of great significance to protecting the integrity of the UAV structure. c It can be calculated based on the yaw angle and side offset, specifically:

[0084]

[0085] Among them, ψ is the heading angle of the aircraft, is the gain coefficient of the aileron to the yaw angle, is the gain coefficient of the aileron contralateral offset.

[0086] At this time, the second heading control structure is:

[0087]

[0088] in, is the second heading control instruction, is the gain coefficient of the rudder to the roll angle.

[0089] At the same time, in order to improve the heading control capability during the post-landing roll phase, for electric propulsion drones, differential motor speed control can be used. That is, the speed difference of the symmetrically positioned motors can be used to achieve rapid response control of the drone, improving the heading control capability during the ground roll after touchdown. Especially during the post-landing roll deceleration phase, as the drone's speed gradually decreases, the effectiveness of heading control achieved by using only the aerodynamic force generated by the rudder becomes increasingly weak. At this time, the asymmetric power generated by the left and right motors can compensate for the lack of heading control by the rudder. Its control structure is:

[0090] n=n t +Δn

[0091] Among them, n is the motor speed command, n t is the motor speed command in the design trim state, Δn is the motor speed adjustment amount, which can be expressed as:

[0092]

[0093] For the left motor, the value of f(x) meets the following requirements:

[0094]

[0095] For the right motor, the value of f(x) meets the following requirements:

[0096]

[0097] The present invention also provides an electronic device, which includes: a memory storing executable instructions; and a processor running the executable instructions in the memory to implement the above-mentioned autonomous landing lateral heading control method of the low-speed fixed-wing UAV.

[0098] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned autonomous landing lateral heading control method of the low-speed fixed-wing UAV.

[0099] To facilitate understanding of the solutions and effects of the embodiments of the present invention, four specific application examples are given below. Those skilled in the art should understand that these examples are only for facilitating understanding of the present invention, and any specific details thereof are not intended to limit the present invention in any way.

[0100] Example 1

[0101] Figure 2 A schematic diagram illustrating five stages and trajectories of autonomous landing of a UAV according to an embodiment of the present invention is shown.

[0102] Figure 3A flow chart of lateral heading control for autonomous landing of a low-speed fixed-wing UAV according to an embodiment of the present invention is shown.

[0103] The autonomous landing process of a drone can be divided into five stages: Figure 2 As shown. The five stages are: fifth side approach, descent, leveling, touchdown and roll after landing. The fifth side approach realizes level flight near the ground (height above the ground H) and the heading alignment of the runway centerline; the descent flies according to the planned descent trajectory, controlling the altitude while ensuring that the speed heading is aligned with the runway centerline; in the leveling stage, the pitch angle of the UAV is adjusted to reduce the descent speed, the nose of the UAV is aligned with the runway centerline, and the roll angle is controlled to be stable in preparation for landing; in the touchdown stage, the UAV landing gear tires touch the ground and begin to decelerate; then immediately enter the roll after landing stage, and use the motor differential control to control the side deviation while decelerating to prevent the UAV from stopping outside the runway. The basic flow chart of the UAV autonomous landing lateral heading control is shown as follows Figure 3 The specific implementation steps of this method are as follows:

[0104] (1) Before preparing for autonomous landing of a drone, it is necessary to assess whether the wind conditions at the approaching site meet the requirements for drone landing. If so, the landing process is initiated; otherwise, the drone waits in the air for the landing window to land.

[0105] (2) After the landing process is initiated, during the final approach and descent phases, the UAV's lateral heading control uses the heading method, that is, the horizontal attitude of the wings is deflected at an angle toward the headwind direction, and the aircraft flies at a zero sideslip angle or a small sideslip angle. At this time, the ground track can be aligned with the runway centerline.

[0106] In the lateral control channel, the inner loop is the roll angle rate, and the outer loop is the roll angle difference; in the heading control channel, the inner loop is the yaw angle rate, and the outer loop is the speed heading difference and the side deviation. The control structure is expressed as:

[0107]

[0108] During this process, the flight is kept at a small sideslip angle, and the roll angle command φ c Normally 0°. Heading command ψ c Determined based on the direction of the UAV’s approach airport runway.

[0109] (3) During the leveling phase, the lateral heading of the UAV is switched from the heading method to the sideslip method, while maintaining stable track control capability (the ground track is aligned with the runway centerline) to avoid damaging lateral loads on the landing gear during touchdown. Specifically, the corresponding wing is lowered according to the crosswind angle, so that the UAV turns in the direction of the wind, and sufficient rudder is applied to prevent turning, so that the longitudinal axis of the UAV is aligned with the runway centerline.

[0110] In this stage, the lateral control channel has an inner loop for the roll angle rate and an outer loop for the proportional-integral (PI) control of the roll angle difference. The integral term is used to reduce the roll angle control error. c The lateral control structure is calculated based on the yaw angle and side offset.

[0111]

[0112] During the leveling phase, the UAV's airspeed decreases and its altitude above the ground gradually decreases. To protect the wings and avoid damage caused by a large roll, the roll angle command φ is required. c The specific requirement is: calculate the maximum allowable roll angle command based on the landing gear height, wing span, and reserve margin. That is, φ c satisfy:

[0113]

[0114] In this stage, the heading control channel has an inner loop for the yaw rate and an outer loop for the roll angle. One of the functions of the rudder is to offset the turning caused by the roll of the drone and achieve effective control of the side deviation. The heading control structure is:

[0115]

[0116] During the leveling phase, it is necessary to evaluate whether the landing requirements are met based on the lateral offset and yaw angle. If so, proceed to the next stage; otherwise, perform a go-around and prepare for the landing process again.

[0117] (4) During the touchdown phase, as in the leveling phase, the lateral heading is controlled using the sideslip method.

[0118] (5) During the rolling phase after landing, on the one hand, the lateral heading is still controlled by the sideslip method; on the other hand, for low-speed fixed-wing UAVs, as the speed gradually decreases, the aerodynamic efficiency of the rudder weakens, and the motor differential is used to improve the directional control ability of the UAV on the runway. Specifically, on the basis of the motor speed command in the trim state, the motor speed command adjustment amount is superimposed, and at the same time, only one side of the motor has a motor speed increment command. Its motor speed control structure is:

[0119] n=n t +Δn

[0120] Among them, the motor speed adjustment amount Δn is:

[0121]

[0122] When the drone deviates longitudinally to the left or lateral deviation to the left, only the left motor is given an incremental command; when the drone deviates longitudinally to the right or lateral deviation to the right, only the right motor is given an incremental command. That is, for the left motor, the value of f(x) meets the following requirements:

[0123]

[0124] For the right motor, the value of f(x) meets the following requirements:

[0125]

[0126] At the same time, it is necessary to limit the motor adjustment value instruction Δn, that is, Δn satisfies:

[0127]

[0128] (6) After the drone slows down and stops on the runway, the autonomous landing process is completed. At this time, the motor speed command increment needs to be cleared to zero, and the motor remains in the parked state.

[0129] Example 2

[0130] The present disclosure provides an electronic device, which includes: a memory storing executable instructions; and a processor running the executable instructions in the memory to implement the above-mentioned autonomous landing lateral heading control method of the low-speed fixed-wing UAV.

[0131] An electronic device according to an embodiment of the present disclosure includes a memory and a processor.

[0132] The memory is used to store non-transitory computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), a hard disk, flash memory, etc.

[0133] The processor may be a central processing unit (CPU) or other form of processing unit having data processing capability and / or instruction execution capability, and may control other components in the electronic device to perform desired functions. In one embodiment of the present disclosure, the processor is used to execute the computer-readable instructions stored in the memory.

[0134] Those skilled in the art should understand that in order to solve the technical problem of how to obtain a good user experience, this embodiment may also include well-known structures such as a communication bus and an interface, and these well-known structures should also be included in the scope of protection of this disclosure.

[0135] For detailed description of this embodiment, please refer to the corresponding description in the aforementioned embodiments, which will not be repeated here.

[0136] Example 3

[0137] An embodiment of the present disclosure provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for autonomous landing lateral heading control of a low-speed fixed-wing UAV is implemented.

[0138] According to an embodiment of the present disclosure, a computer-readable storage medium stores non-transitory computer-readable instructions, which, when executed by a processor, execute all or part of the steps of the aforementioned methods of the embodiments of the present disclosure.

[0139] The above-mentioned computer-readable storage media include, but are not limited to, optical storage media (e.g., CD-ROMs and DVDs), magneto-optical storage media (e.g., MOs), magnetic storage media (e.g., magnetic tapes or mobile hard disks), media with built-in rewritable non-volatile memory (e.g., memory cards), and media with built-in ROM (e.g., ROM cartridges).

[0140] Those skilled in the art should understand that the above description of the embodiments of the present invention is only for the purpose of illustrative purposes only to illustrate the beneficial effects of the embodiments of the present invention, and is not intended to limit the embodiments of the present invention to any given examples.

[0141] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for autonomous landing lateral heading control of a low-speed fixed-wing UAV, characterized in that: include: Determine the route approach and landing process, including final approach, descent, level off, touchdown and post-landing roll; For the fifth approach and the glide path, determining a first lateral control and a first heading control by a heading method; For the process of leveling, touching down and rolling after landing, determining the second lateral control and the second heading control by a sideslip method; With respect to the post-landing rolling process, the motor speed control is determined.

2. The autonomous landing lateral heading control method for a low-speed fixed-wing UAV according to claim 1, wherein: The first lateral control is: in, is the first lateral control instruction, that is, the aileron instruction, ω x is the roll angular rate, φ is the roll angle, φ c is the roll angle command, is the gain coefficient of the aileron to the rolling angle rate, is the gain coefficient of the aileron to the roll angle.

3. The autonomous landing lateral heading control method of a low-speed fixed-wing UAV according to claim 1, wherein: The first heading control is: in, is the first heading control command, that is, the rudder command, ω y is the yaw rate, ψ v is the speed heading, ψ c is the runway heading angle command, dZ is the side deviation of the UAV relative to the runway centerline and its extension line, is the gain coefficient of the rudder to the yaw rate, is the gain coefficient of the rudder to the yaw angle, is the gain coefficient of the rudder opposite side offset.

4. The autonomous landing lateral heading control method of a low-speed fixed-wing UAV according to claim 1, wherein: The second lateral control is: in, It is the second lateral control instruction.

5. The autonomous landing lateral heading control method for a low-speed fixed-wing UAV according to claim 1, wherein: The second heading control is: in, It is the second heading control instruction.

6. The autonomous landing lateral heading control method of a low-speed fixed-wing UAV according to claim 1, wherein: Determine the motor speed control including: Calculate the motor speed adjustment amount; An instruction for controlling the motor speed is determined according to the motor speed adjustment amount.

7. The autonomous landing lateral heading control method for a low-speed fixed-wing UAV according to claim 6, wherein: The motor speed adjustment value Δn is: Among them, Δn is the motor speed adjustment amount.

8. The autonomous landing lateral heading control method of a low-speed fixed-wing UAV according to claim 7, wherein: The command for motor speed control is: n=n t +Δn。 9. An electronic device, characterized in that: The electronic device comprises: A memory storing executable instructions; A processor, wherein the processor runs the executable instructions in the memory to implement the autonomous landing lateral heading control method of the low-speed fixed-wing UAV according to any one of claims 1-8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the autonomous landing lateral heading control method for a low-speed fixed-wing UAV according to any one of claims 1 to 8.

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