UAV Ground Run Braking Anti-Skid Control System and Method

Abstract

The present invention provides an anti-skid control system and method for the ground taxiing brake of an unmanned aerial vehicle, including: S1 obtaining the maximum allowable braking amount to prevent the main wheels from locking according to the state information of the unmanned aerial vehicle during taxiing and the aerodynamic force and moment balance relationship; S2 presetting a threshold value for the heading deviation information of the unmanned aerial vehicle during taxiing to determine whether the unmanned aerial vehicle is unstable; S3 giving a brake correction value according to the judgment result of S2. In the unstable state, the brake correction value <0; in the non-unstable case, the brake correction value = 0; S4 giving a brake set value and sending the brake set value to the brake valve system to implement braking. S5 repeating S1 to S4 to achieve fast and stable braking. The present invention can obtain the maximum allowable braking supply amount to prevent the main wheels from locking during the ground taxiing brake of the unmanned aerial vehicle, monitor in real time whether the heading of the unmanned aerial vehicle during the ground taxiing brake is unstable, and correct the braking supply amount in real time according to whether it is unstable, so as to avoid accidents of heading instability caused by inappropriate braking amount during the ground taxiing brake of the unmanned aerial vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of UAV control, and particularly to a UAV ground taxiing brake anti-skid control system and method.

Background Art

[0002] The ground taxiing stage of a wheeled UAV is the first stage that a UAV flight has to face. However, during the ground taxiing braking process, instability accidents such as tire dragging, tail whipping, heading divergence, rollover, and running off the runway frequently occur to the UAV. The reason for the instability accidents is that when the UAV brakes during ground taxiing, the lateral slip rate is relatively large and enters the unstable region, making the adhesion coefficient of the main wheels become smaller, showing a tendency of locking, and the lateral deviation control stability is greatly reduced, thus leading to the divergence of the lateral deviation control and triggering accidents. Therefore, how to perform brake anti-skid control during ground taxiing has become the key to solving the above problems.

[0003] To address this problem, some researchers start from the control structure and improve the anti-interference ability of UAV taxiing deviation correction by introducing information such as the aircraft nose direction deviation and sideslip angle into the control structure, thereby improving the deviation correction and anti-skid ability of the UAV. However, this can only limitedly improve the taxiing deviation correction performance and cannot truly solve the problem of heading instability caused by brake locking of the UAV. Some researchers start from the brake control system and propose an anti-skid control algorithm and anti-skid system based on the slip rate. This anti-skid system is a part of the brake control system and needs to collect information such as the wheel linear velocity to obtain the slip rate of the wheels. However, it is relatively complex to implement in terms of structure and hardware and is not applicable to UAVs equipped with a simple hydraulic brake system and unable to collect the wheel linear velocity. Therefore, on the basis of improving the deviation correction control, how to achieve anti-skid braking control for UAVs equipped with a simple hydraulic brake system is a problem that needs to be solved.

[0004] Therefore, it is necessary to study a UAV ground taxiing brake anti-skid control system and method to address the deficiencies of the existing technology and solve or mitigate one or more of the above problems.

Summary of the Invention

[0005] In view of this, the present invention provides a UAV ground taxiing brake anti-skid control system and method, which solves the problem of obtaining the maximum allowable brake feed amount of the UAV when the UAV does not have the ability to implement slip rate anti-skid control, and also solves the problems of monitoring the instability of the UAV and correcting the brake feed amount when the UAV shows instability trends such as heading divergence.

[0006] On the one hand, the present invention provides a UAV ground taxiing brake anti-skid control method, and the brake anti-skid control method includes:

[0007] S1: Obtain the maximum allowable braking amount Brake1 to prevent the main wheels from locking based on the state information of the UAV during taxiing and the aerodynamic force and moment balance relationship.

[0008] S2: Preset a threshold for the nose heading deviation information of the UAV during taxiing, and determine whether the UAV is unstable.

[0009] S3: According to the judgment result of S2, give a brake correction value Brake2, where Brake2 ≤ 0.

[0010] In the unstable state, Brake2 < 0; in the non-unstable state, Brake2 = 0.

[0011] S4: Give a brake setting value Brake, where Brake = Brake1 + Brake2 and Brake ≥ 0; and send the brake setting value Brake to the brake valve system to implement braking.

[0012] S5: Repeat S1 - S4 to achieve rapid and stable braking of the UAV.

[0013] For the aspects and any possible implementation manners as described above, a further implementation manner is provided. Specifically, S1 includes:

[0014] S11: Obtain the elevator deflection angle information, attitude information, and speed information of the UAV during taxiing.

[0015] S12: Obtain the aerodynamic data, mass information, three-wheel station information, front wheel rolling friction coefficient, main wheel rolling friction coefficient, main wheel sliding friction coefficient, and the "brake opening - braking force" correspondence table of the UAV.

[0016] S13: Through the information obtained in S11 and S12, perform force and moment balance calculations to obtain the normal pressure of the main wheels on the runway and the main wheel sliding friction force.

[0017] S14: Obtain a correction coefficient (0.5 - 1.0) based on the change in the center of gravity, aerodynamic calculation error, and safety factors, and multiply the main wheel sliding friction force by the correction coefficient to obtain the maximum allowable braking force during the taxiing stage.

[0018] S15: According to the "brake opening - braking force" correspondence table and the maximum allowable braking force during the taxiing stage in S14, obtain the maximum allowable braking amount.

[0019] For the aspects and any possible implementation manners as described above, a further implementation manner is provided. The value range of the real-time braking amount Brake1 is [0%, 100%]. Without loss of generality, 0% corresponds to a braking amount of 0; 100% corresponds to full braking.

[0020] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The aerodynamic data of the drone includes, but is not limited to, the lift coefficient and the pitching moment coefficient.

[0021] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The three-wheel standing position information of the drone includes the horizontal and vertical distances from the main wheel to the center of gravity and the horizontal and vertical distances from the front wheel to the center of gravity.

[0022] For the aspects and any possible implementation manners described above, a further implementation manner is provided. The "brake opening - braking force" correspondence table and the maximum allowable braking force are used to determine the brake opening, that is, the maximum allowable braking amount, by interpolation.

[0023] For the aspects and any possible implementation manners described above, a further implementation manner is provided. Specifically, S2 includes:

[0024] S21: Preset a threshold value in the statistical sense for the deviation information of the nose heading angle during the drone's taxiing.

[0025] S22: Periodically collect the deviation information of the nose heading angle during the drone's ground taxiing and braking.

[0026] S23: Conduct a statistical analysis on the deviation information of the nose heading angle during the drone's taxiing collected in S22 to obtain the extreme difference value and the absolute maximum value of the deviation information of the nose heading angle during the drone's taxiing.

[0027] S24: Determine whether the extreme difference value and the absolute maximum value of the deviation information of the nose heading angle during the drone's taxiing exceed the threshold value. If neither exceeds the threshold value, it is determined that the drone's heading is in a non - unstable state; otherwise, it is determined that the drone's heading is in an unstable state.

[0028] For the aspects and any possible implementation manners described above, a further implementation manner is provided. Specifically, the deviation information of the nose heading during the drone's taxiing is the deviation information between the nose heading of the drone and the runway heading angle.

[0029] For the aspects and any possible implementation manners described above, a further implementation manner is provided. Specifically, S3 includes:

[0030] S31: Preset a step amount dBrake for the brake correction value, dBrake > 0, and the brake correction value Brake2 = - 1 × n × dBrake, where n = 0, 1, 2...

[0031] S32: According to the judgment result of S2, if the drone's heading is unstable, then n is incremented by 1 based on the current value; if the drone's heading is not unstable, then n = 0.

[0032] For the aspects and any possible implementation manners as described above, a skid prevention control system for an unmanned aerial vehicle (UAV) during ground taxiing braking is further provided. The skid prevention control system for braking includes:

[0033] A maximum allowable braking amount acquisition module, which acquires the maximum allowable braking amount to prevent the main wheels from locking based on the state information of the UAV during taxiing and the aerodynamic force and moment balance relationship;

[0034] An instability state judgment module, which presets a threshold value in the statistical sense of the deviation information of the nose heading of the UAV during taxiing, and judges whether the UAV is unstable by periodically collecting the deviation information of the nose heading of the UAV and comparing it with the threshold value;

[0035] A real-time correction module, which gives a braking correction value according to the instability judgment result, obtains a braking set value by adding the maximum allowable braking amount and the braking correction value, and brakes the UAV in real time with the braking set value to achieve fast and stable braking.

[0036] Compared with the prior art, the present invention can obtain the following technical effects:

[0037] 1) The present invention is convenient for engineering implementation and has strong applicability. Although it is designed for a UAV with a nose-wheel landing gear, combined correction control of the nose wheel steering and rudder, and a simple hydraulic braking system for the main wheels, it is also applicable to the braking control of other UAVs;

[0038] 2) The real-time performance and rapidity are enhanced. With the strong computing power of the flight control computer, it can calculate in real time the maximum allowable braking amount that does not cause the main wheels to lock, quickly monitor the state of the UAV, and timely correct the braking amount, and can fully exert the braking potential of the braking system.

[0039] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned technical effects simultaneously.

Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. 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 is a force and moment diagram of the UAV during ground taxiing provided by an embodiment of the present invention (the coordinates are in the European and American systems);

[0042] Figure 2 is a flowchart of a real-time monitoring of the UAV heading instability and a real-time correction scheme of the braking amount provided by an embodiment of the present invention.

[0043] Figure 3 It is the ground speed statistical chart of a certain UAV after braking during a certain ground high-speed taxiing provided by an embodiment of the present invention;

[0044] Figure 4 It is the given braking statistical chart of a certain UAV during a certain ground high-speed taxiing provided by an embodiment of the present invention;

[0045] Figure 5 It is the statistical chart of the heading angle and heading angle rate of a certain UAV after braking during a certain ground high-speed taxiing provided by an embodiment of the present invention.

Specific implementation manners

[0046] For a better understanding of the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0047] It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0049] The present invention provides a method for controlling anti-skid braking during ground taxiing of a UAV. The anti-skid braking control method includes:

[0050] A method for controlling anti-skid braking during ground taxiing of a UAV. The anti-skid braking control method includes:

[0051] S1: According to the state information of the UAV during taxiing and the aerodynamic force and moment balance relationship, obtain the maximum allowable braking amount Brake1 to prevent the main wheels from locking;

[0052] S2: Preset a threshold value for the heading deviation information of the UAV during taxiing, and determine whether the UAV is unstable;

[0053] S3: According to the judgment result of S2, give a braking correction value Brake2, where Brake2 ≤ 0;

[0054] In the unstable state, Brake2 < 0; in the non-unstable state, Brake2 = 0;

[0055] S4: Give the brake set value Brake, where Brake = Brake1 + Brake2 and Brake ≥ 0; and send the brake set value Brake to the brake valve system to apply the brake.

[0056] S5: Repeat S1 - S4 to achieve rapid and stable braking of the UAV.

[0057] The specific steps of S1 include:

[0058] S11: Obtain the elevator deflection angle information, attitude information, and speed information of the UAV during taxiing.

[0059] S12: Obtain the aerodynamic data, mass information, three - wheel station information, front - wheel rolling friction coefficient, main - wheel rolling friction coefficient, main - wheel sliding friction coefficient, and the "brake opening - braking force" correspondence table of the UAV.

[0060] S13: Perform force and moment balance calculations based on the information obtained in S11 and S12 to obtain the normal pressure of the main wheels on the runway and the main - wheel sliding friction force.

[0061] S14: Obtain a correction factor (0.5 - 1.0) based on the change in the center of gravity, aerodynamic calculation error, and safety factors, and multiply the main - wheel sliding friction force by the correction factor to obtain the maximum allowable braking force during the taxiing stage.

[0062] S15: Obtain the maximum allowable brake amount based on the "brake opening - braking force" correspondence table and the maximum allowable braking force during the taxiing stage in S14.

[0063] In the above - mentioned aspects and any possible implementation manners, a further implementation manner is provided. The value range of the real - time brake amount Brake1 is [0%, 100%]. Without loss of generality, 0% corresponds to a brake amount of 0; 100% corresponds to full braking. The aerodynamic data of the UAV includes, but is not limited to, the lift coefficient and pitch - moment coefficient. The three - wheel station information of the UAV includes the horizontal and vertical distances from the main wheels to the center of gravity and the horizontal and vertical distances from the front wheels to the center of gravity. The "brake opening - braking force" correspondence table and the maximum allowable braking force are used to determine the brake opening, that is, the maximum allowable brake amount, by interpolation.

[0064] The specific steps of S2 include:

[0065] S21: Preset the threshold value in the statistical sense of the deviation information of the nose - heading angle of the UAV during taxiing.

[0066] S22: Periodically collect the deviation information of the nose - heading angle of the UAV during the ground taxiing and braking process.

[0067] S23: Perform statistical analysis on the deviation information of the nose heading angle during the taxiing of the UAV collected in S22 to obtain the range value and the absolute maximum value of the deviation information of the nose heading angle during the taxiing of the UAV.

[0068] S24: Determine whether the range value and the absolute maximum value of the deviation information of the nose heading angle during the taxiing of the UAV exceed the threshold. If neither exceeds the threshold, it is determined that the UAV heading is in a non-unstable state; otherwise, it is determined that the UAV heading is in an unstable state. The deviation information of the nose heading during the taxiing of the UAV is specifically the deviation information between the nose heading of the UAV and the runway heading angle.

[0069] The specific steps of S3 include:

[0070] S31: Preset the step size dBrake of the brake correction value, where dBrake > 0, and the brake correction value Brake2 = -1 × n × dBrake, where n = 0, 1, 2...

[0071] S32: According to the judgment result of S2, if the UAV heading is unstable, then n is incremented by 1 based on the current value; if the UAV heading is not unstable, then n = 0.

[0072] The present invention also provides a ground taxiing brake anti-skid control system for a UAV. The brake anti-skid control system includes:

[0073] A maximum allowable braking amount acquisition module, which acquires the maximum allowable braking amount to prevent the main wheels from locking according to the state information during the taxiing of the UAV and the aerodynamic force and moment balance relationship.

[0074] An instability state judgment module, which presets a threshold in the statistical sense of the deviation information of the nose heading during the taxiing of the UAV, and judges whether the UAV is unstable by periodically collecting the nose heading deviation information of the UAV and comparing it with the threshold.

[0075] A real-time correction module, which gives a brake correction value according to the instability judgment result, and obtains a brake setting value by adding the maximum allowable braking amount and the brake correction value, and performs real-time braking on the UAV with the brake setting value to achieve fast and stable braking.

[0076] When the present invention is specifically applied, the method is as follows:

[0077] 1. Real-time braking amount calculation scheme

[0078] 1) Obtain relevant databases such as the aerodynamic data of the aircraft in advance and write them into the flight control program. The database contains information such as the lift coefficient and pitch moment coefficient of the aircraft, which is used to calculate the aerodynamic lift and aerodynamic pitch moment of the aircraft in real time. Bind the mass and total fuel quantity of the UAV in advance to facilitate the program to calculate the mass and gravity of the UAV in real time.

[0079] 2) Obtain the three-wheel station information of the aircraft, such as Figure 1 shown, including the horizontal distance l from the nose wheel to the aircraft's center of gravity f , the vertical distance h from the nose wheel to the aircraft f , the horizontal distance l from the main wheels to the aircraft b , the vertical distance h from the main wheels to the aircraft b .

[0080] 3) Through ground low-speed taxiing tests, obtain the rolling friction coefficient μ f of the nose wheel and the rolling friction coefficient μ b of the main wheels; through ground tests or data queries, obtain the sliding friction coefficient μ s between the main wheel material and the runway.

[0081] 4) Obtain the corresponding relationship table of "brake opening - braking force" through experimental tests.

[0082] 5) Combine Figure 1 the described force conditions, perform force and moment balance calculations, and obtain the normal pressure N b of the main wheels on the runway. The specific calculation method is as follows.

[0083] Force balance formula:

[0084] N f + N b = G - L (1)

[0085] In the formula, N f is the support force of the ground on the nose wheel; N b is the total support force of the ground on the double main wheels, that is, the normal pressure of the main wheels on the runway; G is the gravity of the aircraft; L is the aerodynamic lift of the aircraft.

[0086] In terms of moments, the aircraft is subject to the following 6 moments, including:

[0087] a) The nose wheel support force N f produces a nose-up moment: N f l f .

[0088] b) The nose wheel rolling friction Q f produces a nose-down moment: -Q f h f = -μ f N f h f .

[0089] c) The main wheel support force N b produces a nose-down moment: -N b l b .

[0090] d) Rolling friction force Q of the main wheel b Nosing moment generated: -Q b h b = -μ b N b h b 。

[0091] e) Sliding friction force Q of the main wheel s Nosing moment generated: -Q s h b = -μ s N b h b 。

[0092] f) Aerodynamic pitching moment of the aircraft: M.

[0093] Moment balance formula:

[0094] N f (l f -μ f h f ) - N b (μ b h b +μ s h b +l b ) + M = 0 (2)

[0096] Combining equations (1) and (2), the normal pressure of the main wheel on the runway can be obtained

[0097]

[0098] Write equation (3) into the flight control program, and the program calculates the normal pressure of the main wheel on the runway in real time.

[0099] 6) From the normal pressure N of the main wheel on the runway b and the sliding friction coefficient μ of the main wheel s , calculate the sliding friction force Q of the main wheel s 。

[0100] 7) Considering the changes in the center of gravity, aerodynamic calculation errors, and safety factors, multiply the sliding friction force Q s by a correction factor (0.5 - 1.0, determined by actual taxiing), which is the maximum allowable braking force at this speed. Then, combined with the "brake opening - braking force" correspondence table, the corresponding brake opening at this braking force can be interpolated, that is, the real-time braking amount.

[0101] 2. Real-time monitoring of UAV heading instability and real-time correction scheme of braking amount

[0102] 1) Real-time monitoring scheme for UAV heading instability

[0103] The monitoring process is as Figure 2 shown. When the UAV brakes during ground taxiing, if the given braking amount is too large, it will cause the heading of the UAV to become unstable, and the information such as the nose heading angle of the UAV will first show a divergent trend. During the ground taxiing braking process of the UAV, the nose yaw angle of the UAV (the nose yaw angle is the nose heading angle minus the runway heading angle) is periodically collected. If the collection is completed, the data is statistically analyzed to obtain the extreme value and the absolute maximum value in the nose yaw angle information, and they are respectively compared with the threshold values. If neither the extreme value nor the absolute maximum value exceeds the threshold, it is considered that the UAV heading is stable; otherwise, it is considered that the UAV heading is divergent.

[0104] 2) Real-time correction scheme for UAV braking amount

[0105] Preset the braking correction step amount dBrake (>0). The braking correction value Brake2 = -1 × n × dBrake, n = 0, 1, 2…

[0106] If it is determined that the current UAV heading is not unstable, then set n = 0 and output the braking correction amount Brake2 as 0;

[0107] If it is determined that the current UAV heading is unstable, then n is incremented by 1 based on the current value.

[0108] The above correction scheme is illustrated as follows. If the current value of n is 0 and it is determined in this cycle that the UAV heading is unstable, then n = 1 and Brake2 = -1 × 1 × dBrake. If it is determined in the next cycle that the heading is still unstable, then n = 2, and Brake2 = -1 × 2 × dBrake. If the UAV continues to have an unstable heading, then n continues to increase. If it is determined in the next cycle that the heading becomes stable, then set n to 0 and Brake2 is equal to 0. The braking given value Brake for each cycle is Brake = Brake1 + Brake2; the braking given value Brake is sent to the brake valve system to implement braking. In fact, n in the braking correction value Brake2 will not increase infinitely, and it is necessary to ensure that the final braking given value Brake ≥ 0.

[0109] 3. Running inside the flight control computer

[0110] Implement the above real-time braking amount calculation scheme, real-time monitoring of UAV heading instability, and real-time correction scheme for braking amount through code and run it in real time inside the flight control computer. The flight control computer periodically calculates the real-time braking amount, and then decides whether to correct the braking amount according to the monitoring result of heading instability, and then sends the braking command to the brake valve system to achieve anti-skid braking control.

[0111] With the help of the strong computing power of the flight control computer, the present invention fully exploits the potential of the braking system, improves the reliability of the ground taxiing control of the UAV, and ensures the safety of the ground taxiing braking of the UAV.

[0112] Embodiment 1:

[0113] As Figures 3 - 5 shown, after a certain UAV adopts the present invention, a high-speed taxiing test is carried out. The preset yaw angle range threshold of the nose is 2°, the absolute maximum value threshold is 4°, and the brake correction step dBrake is 5%. The test situation is as follows: After the ground speed of the UAV reaches 32.8 m / s, it starts to enter the braking deceleration stage. Thereafter, according to the aircraft state information and the aerodynamic force and moment balance relationship, the maximum allowable braking amount Brake1 calculated in real time varies between 37% and 39%. Before 4509 s, since the yaw angle state of the aircraft nose is good and the program considers the current heading stable, the maximum allowable braking amount is not corrected, and the brake given value Brake = Brake1. After 4509 s, the heading angle rate and the yaw angle of the nose gradually increase. The program collects that the range in the yaw angle of the nose exceeds the threshold, considers the heading unstable, and gives a brake correction amount Brake2 = -1×1×dBrake, that is, -5%. At this time, the brake given value is reduced from 38% to 33%. Subsequently, the heading angle rate and the heading angle of the nose quickly converge. The program collects that the range of the yaw angle of the nose is less than the threshold, considers the heading stable, clears the brake correction amount Brake2, and the brake given value Brake returns to the updated maximum allowable braking amount Brake1 again, that is, 38%. Subsequently, the UAV decelerates smoothly and stops taxiing.

[0114] The ground taxiing test shows that the present invention can effectively improve the reliability of the ground taxiing of the UAV and ensure the safety of the ground taxiing braking of the UAV.

[0115] The above has introduced in detail a ground taxiing anti-skid control system and method for a UAV provided by an embodiment of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

[0116] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not distinguish components by the difference in names, but by the difference in functions of the components. As used throughout the specification and claims, the terms "comprising" and "including" are open-ended terms and should be interpreted as "comprising / including but not limited to". "Substantially" means within an acceptable error range. Those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The following description in the specification is the preferred embodiment for implementing the present application, but the description is for the purpose of explaining the general principles of the present application and not for limiting the scope of the present application. The protection scope of the present application shall be subject to what is defined by the appended claims.

[0117] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a good or system including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such good or system. Without further limitation, an element defined by the statement "including one..." does not exclude the presence of another identical element in the good or system including the said element.

[0118] It should be understood that the term "and / or" used herein is merely an associative relationship describing associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0119] The above description illustrates and describes several preferred embodiments of the present application. However, as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the application concept described herein through the above teachings or the technology or knowledge in the relevant field. Any changes and variations made by those skilled in the art without departing from the spirit and scope of the present application shall fall within the protection scope of the appended claims of the present application.

Claims

1. A method for anti-skid control of a drone during ground taxiing braking, characterized in that, The described anti-skid braking control method includes: S1: According to the state information of the drone during taxiing and the aerodynamic force and moment balance relationship, obtain the maximum allowable braking amount Brake1 to prevent the main wheels from locking. S2: Preset a threshold value for the deviation information of the nose heading of the drone during taxiing, and determine whether the drone is unstable. S3: According to the judgment result of S2, give a braking correction value Brake2, where Brake2 ≤ 0. In the unstable state, Brake2 < 0; in the non-unstable state, Brake2 = 0. S4: Give a braking set value Brake, where Brake = Brake1 + Brake2, and Brake ≥ 0; and send the braking set value Brake to the brake valve system to implement braking. S5: Repeat S1 to S4 to achieve rapid and stable braking of the drone. The specific content of S1 includes: S11: Obtain the elevator deflection angle information, attitude information, and speed information of the drone during taxiing. S12: Obtain the aerodynamic data of the drone, mass information, three-wheel station information, front wheel rolling friction coefficient, main wheel rolling friction coefficient, main wheel sliding friction coefficient, and the "brake opening - braking force" corresponding relationship table. S13: Through the information obtained in S11 and S12, perform force and moment balance calculations to obtain the normal pressure of the main wheels on the runway and the sliding friction force of the main wheels. S14: Obtain a correction coefficient based on the change in the center of gravity, aerodynamic calculation error, and safety factors, and multiply the sliding friction force of the main wheels by the correction coefficient to obtain the maximum allowable braking force during the taxiing stage. S15: According to the "brake opening - braking force" corresponding relationship table and the maximum allowable braking force in S14, obtain the maximum allowable braking amount. The specific content of S2 includes: S21: Preset a threshold value in the statistical sense for the deviation information of the nose heading angle of the drone during taxiing. S22: Periodically collect the deviation information of the nose heading angle of the drone during the ground taxiing braking process of the drone. S23: Perform statistical analysis on the deviation information of the nose heading angle of the drone collected in S22 to obtain the extreme difference value and the absolute maximum value of the deviation information of the nose heading angle of the drone during taxiing. S24: Judge whether the extreme difference value and the absolute maximum value of the deviation information of the nose heading angle of the drone during taxiing exceed the threshold value. If neither exceeds the threshold value, it is judged that the drone heading is in a non-unstable state; otherwise, it is judged that the drone heading is in an unstable state.

2. The anti-lock braking control method according to claim 1, wherein The value range of the maximum allowable braking amount Brake1 is [0%, 100%], where 0% corresponds to a braking amount of 0; 100% corresponds to full braking.

3. The anti-lock braking control method according to claim 1, characterized in that The aerodynamic data of the drone includes, but is not limited to, the lift coefficient and the pitch moment coefficient.

4. The anti-lock braking control method according to claim 1, characterized in that The three-wheel station information of the drone includes the horizontal and vertical distances from the main wheel to the center of gravity and the horizontal and vertical distances from the front wheel to the center of gravity.

5. The anti-lock braking control method according to claim 1, wherein According to the "brake opening - braking force" corresponding relationship table and the maximum allowable braking force, determine the brake opening, that is, the maximum allowable braking amount, by interpolation.

6. The anti-skid braking control method according to claim 1, characterized in that The deviation information of the nose heading of the drone during taxiing is specifically the deviation information between the nose heading of the drone and the runway heading angle.

7. The anti-lock braking control method according to claim 1, characterized in that, The specific content of S3 includes: S31: The step size dBrake of the preset brake correction value, where dBrake > 0, and the brake correction value Brake2 = -1 × n × dBrake, where n = 0, 1, 2… S32: According to the judgment result of S2, if the UAV heading is unstable, then n is incremented by 1 based on the current value; if the UAV heading is stable, then n = 0.

8. An anti-skid control system for the ground taxiing braking of an unmanned aerial vehicle, which is implemented by the anti-skid braking control method according to any one of claims 1-7, characterized in that The brake anti-skid control system includes: a maximum allowable braking amount acquisition module that acquires the maximum allowable braking amount to prevent the main wheels from locking based on the state information of the UAV during taxiing and the aerodynamic force and moment balance relationship; an instability state judgment module that presets a threshold in the statistical sense for the deviation information of the nose heading of the UAV during taxiing, and judges whether the UAV is unstable by periodically collecting the nose heading deviation information of the UAV and comparing it with the threshold; a real-time correction module that gives a brake correction value according to the instability judgment result, and obtains a brake set value by adding the maximum allowable braking amount and the brake correction value, and performs real-time braking on the UAV with the brake set value to achieve fast and stable braking.

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