An anti-skid control method for coordinated turning of aircraft ground main wheels

Abstract

The present invention relates to a method for preventing sideslip in coordinated turning of aircraft ground main wheels. The method includes: obtaining the operating conditions of the aircraft and the tire position coordinates; calculating and determining the instantaneous turning center point of the aircraft on the ground when the aircraft is taxiing; calculating the sideslip angles of each tire corresponding to different front wheel angles according to the relationship between the tire position coordinates, the instantaneous turning center point of the aircraft on the ground, and the front wheel angle and the main wheel angle; calculating the sideslip stiffness of each tire; calculating the lateral force of each tire; obtaining the critical lateral force of the tire based on the critical dimensionless sideslip angle and the lateral force of each tire; determining the aircraft sideslip boundary conditions with the criterion that the lateral force of each tire does not exceed the critical lateral force; calculating the critical front wheel angles at different taxiing speeds, obtaining the sideslip safety envelope during coordinated turning of the main wheels, and controlling the actual front wheel angle of the aircraft based on the sideslip safety envelope. Compared with the prior art, the present invention has the advantages of high accuracy, high safety, etc.

Description

Technical Field

[0001] The present invention relates to aircraft anti-skid control, and particularly to an anti-skid control method for coordinated turning of aircraft main landing gears on the ground. Background Art

[0002] With the continuous growth of air transportation demand, civil aircraft are also developing towards wide-body aircraft with large carrying capacities. Wide-body aircraft have relatively large takeoff and landing weights, which pose higher requirements for the layout of the landing gear system and the runway load-bearing capacity. Aircraft ground taxiing and turning is the main form of aircraft ground movement. Modern civil aircraft are required to quickly taxi off the runway and turn into the taxiway to reduce the runway occupancy time, improve the airport operation efficiency, enhance the aircraft ground mobility, and ensure the safety of aircraft takeoff and landing.

[0003] When a wide-body aircraft makes a ground turning movement, it is desired to use a front wheel steering angle as large as possible to reduce the turning radius, a relatively large front wheel steering rate to shorten the time to steer to the appropriate front wheel steering angle, and a relatively high taxiing speed to shorten the runway occupancy time and improve the airport operation efficiency. However, when the front wheel steering angle, front wheel steering rate, and taxiing speed of the aircraft are too large, it may cause wheel skidding, resulting in the pilot losing the ability to control the aircraft and posing a safety threat to passengers and crew. The current control method for aircraft ground turning movement calculates the sideslip angle by treating the tire as a whole for the calculation of the lateral force, and does not distribute the vertical load based on the tires of different axles of the front main landing gear and different distribution situations, resulting in low accuracy of the overall force analysis of the aircraft and reducing the mobility and safety of wide-body aircraft during ground turning movement. Summary of the Invention

[0004] The purpose of the present invention is to provide an anti-skid control method for coordinated turning of aircraft main landing gears on the ground to overcome the above-mentioned defects existing in the prior art. Based on the relationship between the front main landing gear steering angles under the optimized constraints of the forces on the main landing gear during coordinated turning of aircraft main landing gears on the ground, considering the forces on independent elastic tires, it comprehensively reflects the dynamic characteristics of multi-wheel and multi-strut wide-body aircraft during coordinated turning of main landing gears on the ground, obtains the sideslip boundary of coordinated turning of aircraft main landing gears on the ground, controls the actual front wheel steering angle of the aircraft, and prevents the aircraft from skidding.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] An anti-skid control method for coordinated turning of aircraft main landing gears on the ground, comprising the following steps:

[0007] S1. Obtain the aircraft operating conditions and the tire position coordinates, where the aircraft operating conditions include the aircraft taxiing speed and the tire vertical load corresponding to the aircraft taxiing speed;

[0008] S2. Calculate and determine the instantaneous turning center point of the aircraft on the ground when the aircraft is taxiing, according to the relationship between the front wheel turning angle and the main wheel turning angle under the optimization constraint of the aircraft ground main wheel coordinated turning dynamics equation, where the dynamics equation includes a force balance equation and a moment balance equation;

[0009] S3. Calculate the sideslip angles of each tire corresponding to different front wheel turning angles according to the tire position coordinates, the instantaneous turning center point of the aircraft on the ground, and the relationship between the front wheel turning angle and the main wheel turning angle;

[0010] S4. Calculate the sideslip stiffness of each tire according to the vertical load of the tire and the tire parameters;

[0011] S5. Calculate the dimensionless sideslip angle of the tire according to the sideslip angle and the sideslip stiffness, and calculate the lateral force of each tire based on the dimensionless sideslip angle of the tire and the vertical load of the tire;

[0012] S6. Based on the critical dimensionless sideslip angle and the lateral force of each tire, and corrected based on the Bridgestone - Fiala model, obtain the critical lateral force of the tire;

[0013] S7. Determine the sideslip boundary condition of the aircraft with the criterion that the lateral force of each tire does not exceed the critical lateral force;

[0014] S8. According to the sideslip boundary condition, calculate the critical front wheel turning angle at different taxiing speeds, obtain the sideslip safety envelope during the coordinated turning of the main wheels, and control the actual front wheel turning angle of the aircraft based on the sideslip safety envelope.

[0015] Further, the vertical load of the tire is obtained based on the vertical load distribution of the nose landing gear and the main landing gear, and the vertical load distribution of the front, middle, and rear axles of the main landing gear. Among them, the calculation expression for the vertical load distribution of the nose landing gear and the main landing gear is:

[0016]

[0017] where, V1 is the vertical load of the nose landing gear of the aircraft, V2 is the vertical load of the outer main landing gear of the aircraft during turning, V3 is the vertical load of the inner main landing gear of the aircraft during turning, V is the total vertical load of the aircraft, η is the vertical load distribution ratio of the nose landing gear when the aircraft is static, m is the mass of the aircraft, v is the taxiing speed, R is the distance from the instantaneous turning center point of the aircraft on the ground to the center of gravity, (x, y) is the coordinate of the instantaneous turning center point of the aircraft on the ground, L M is the distance between the two main landing gears, and H is the height of the center of gravity of the aircraft;

[0018] The calculation expression for the vertical load distribution of the front, middle, and rear axles of the main landing gear is:

[0019]

[0020] Among them, V F is the vertical load on the front axle of the main landing gear of the aircraft, V M is the vertical load on the middle axle of the main landing gear of the aircraft, V A is the vertical load on the rear axle of the main landing gear of the aircraft, L da is the distance between the middle and rear axles of the main landing gear, L df is the distance between the front and middle axles of the main landing gear, μ is the rolling friction coefficient, and h is the distance between the intersection point of the main landing gear support and the buffer strut.

[0021] Furthermore, each of the front, middle, and rear axles has 2 coaxial tires respectively. For the vertical load of the coaxial tires, it is divided into symmetric distribution and asymmetric distribution cases for distribution.

[0022] Furthermore, in the case of symmetric distribution, the vertical load of the coaxial tires is equally distributed.

[0023] Furthermore, in the case of asymmetric distribution, the vertical load of the coaxial tires on the paved runway is distributed according to 6:4, and the vertical load of the coaxial tires on the semi-paved or unpaved runway is distributed according to 7:3.

[0024] Furthermore, the specific expression for calculating the dimensionless sideslip angle of the tire according to the sideslip angle and sideslip stiffness is:

[0025]

[0026] Among them, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i, φ i ′ is the dimensionless sideslip angle of the tire numbered i, is the sideslip stiffness of the tire numbered i, is the sideslip angle of the tire numbered i.

[0027] Furthermore, according to the Bridgestone-Fiala model, the critical dimensionless sideslip angle of the tire is 1.54.

[0028] Furthermore, the specific expression for calculating the lateral force of each tire based on the dimensionless sideslip angle and vertical load of the tire is:

[0029] N i =(φ i ′ - 0.0668φ i ′ 2 - 0.1032φ i ′ 3 )μ y V i ′

[0030] Among them, N i is the lateral force of the tire numbered i, μ yis the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i, φ i ′ is the dimensionless sideslip angle of the tire numbered i.

[0031] Furthermore, the calculation expression of the corrected critical lateral force of the tire is:

[0032] [N i = 1.0063μ y V i ′

[0033] Among them, [N i is the critical lateral force of the tire numbered i, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i.

[0034] Furthermore, the aircraft sideslip boundary conditions include the condition that the front wheels do not experience sideslip and the condition that the main wheels do not experience sideslip.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) Compared with the prior aircraft ground turning anti-sideslip technology, when calculating the vertical load of the tire in the present invention, it is obtained based on the vertical load distribution of the nose landing gear and the main landing gear, as well as the vertical load distribution of the front, middle, and rear axles of the main landing gear, considering the symmetric distribution and asymmetric distribution situations of the actual aircraft, more accurately calculating the sideslip stiffness of each tire, accurately analyzing the force, and improving the accuracy of the control method.

[0037] (2) Based on the relationship between the front and main wheel angles under the optimization constraint of the force on the main landing gear during the coordinated turning of the main wheels, it comprehensively reflects the dynamic characteristics of the aircraft during the coordinated turning of the main wheels, considering the influence of tire elasticity on the force analysis. Compared with the prior aircraft ground turning anti-sideslip technology where the tire is simplified to be rigid, this solution improves the accuracy of the overall force analysis of the aircraft and further improves the accuracy of the sideslip boundary of the aircraft ground main wheel coordinated turning. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the flowchart of the present invention;

[0039] Figure 2 is the schematic diagram of the tire layout of the aircraft landing gear of the present invention;

[0040] Figure 3 is the schematic diagram of the force on the aircraft of the present invention;

[0041] Figure 4 is the schematic diagram of the sideslip angle of the aircraft tire of the present invention;

[0042] Figure 5This is the sideslip safety envelope of the present invention. Detailed implementation manners

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation procedures are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0044] Since the forces acting on the aircraft during a ground turn are very complex, factors such as runway surface flatness, pilot control methods, and aircraft speed will all affect the forces acting on it. To simplify the analysis, the following assumptions are made:

[0045] (1) During the turn, the aircraft maintains a constant center of gravity height and the fuselage is parallel to the ground.

[0046] (2) The aircraft's center of gravity trajectory is used to represent the aircraft's movement trajectory.

[0047] (3) The tires are elastic tires.

[0048] (4) The turning center of the aircraft's movement is used to represent the curvature center of the aircraft's movement trajectory, and the influence of the instantaneous center's own acceleration is ignored.

[0049] (5) Differential engine turning is not used.

[0050] (6) The influence of runway surface unevenness is ignored.

[0051] The present invention provides an anti-sideslip control method for coordinated turning of the main landing gears of an aircraft on the ground. The flow chart of the method is as Figure 1 shown, and the method includes the following steps:

[0052] S1. Obtain the aircraft operating conditions and the tire position coordinates. The aircraft operating conditions include the aircraft taxiing speed and the tire vertical load corresponding to the taxiing speed.

[0053] The tire position coordinates include the coordinates of the outer turning tire n1 of the nose landing gear, the inner turning tire n2 of the nose landing gear, the outer turning tire f1 of the front axle of the outer turning main landing gear, the inner turning tire f2 of the front axle of the outer turning main landing gear, the outer turning tire f3 of the front axle of the inner turning main landing gear, the inner turning tire f4 of the front axle of the inner turning main landing gear, the outer turning tire m1 of the middle axle of the outer turning main landing gear, the inner turning tire m2 of the middle axle of the outer turning main landing gear, the outer turning tire m3 of the middle axle of the inner turning main landing gear, the inner turning tire m4 of the middle axle of the inner turning main landing gear, the outer turning tire a1 of the rear axle of the outer turning main landing gear, the inner turning tire a2 of the rear axle of the outer turning main landing gear, the outer turning tire a3 of the rear axle of the inner turning main landing gear, and the inner turning tire a4 of the rear axle of the inner turning main landing gear.

[0054] The vertical load of the tire is obtained based on the vertical load distribution of the nose landing gear and the main landing gear, as well as the vertical load distribution of the front, middle, and rear axles of the main landing gear respectively.

[0055] The calculation expression for the vertical load distribution of the nose and main landing gears is as follows:

[0056]

[0057] In the formula, V1 is the vertical load of the nose landing gear of the aircraft, V2 is the vertical load of the outer main landing gear during aircraft turning, V3 is the vertical load of the inner main landing gear during aircraft turning, V is the total vertical load of the aircraft, η is the vertical load distribution ratio of the nose landing gear when the aircraft is static, m is the mass of the aircraft, v is the taxiing speed, R is the distance from the instantaneous turning center point on the ground of the aircraft to the center of gravity, (x, y) is the coordinate of the instantaneous turning center point on the ground of the aircraft, L M is the distance between the two main landing gears, and H is the height of the center of gravity of the aircraft.

[0058] The calculation expressions for the vertical load distributions of the front, middle, and rear axles of the main landing gear are as follows:

[0059]

[0060] In the formula, V F is the vertical load of the front axle of the main landing gear of the aircraft, V M is the vertical load of the middle axle of the main landing gear of the aircraft, V A is the vertical load of the rear axle of the main landing gear of the aircraft, L da is the distance between the middle and rear axles of the main landing gear, L df is the distance between the front and middle axles of the main landing gear, μ is the rolling friction coefficient, and h is the distance from the intersection point of the main landing gear support and the buffer strut.

[0061] There are two coaxial tires on the front, middle, and rear axles of the main landing gear. For coaxial tires, the principle of vertical load distribution is as follows: In the case of symmetric distribution, the vertical loads of the coaxial tires are equally distributed; in the case of asymmetric distribution, on a paved runway, the vertical loads of the coaxial tires are distributed according to 6:4, and on a semi-paved or unpaved runway, the vertical loads of the coaxial tires are distributed according to 7:3.

[0062] S2. According to the aircraft ground main wheel coordinated turning dynamics equation and the relationship between the front turning wheel angle and the main wheel angle under the optimization constraint of the main landing gear force, calculate and determine the instantaneous turning center point on the ground of the aircraft at the taxiing speed.

[0063] The relationship between the front turning wheel angle and the main wheel angle and the instantaneous turning center point on the ground of the aircraft satisfy the force balance equation and the moment balance equation in the aircraft ground main wheel coordinated turning dynamics equation.

[0064] The force balance equation in the aircraft ground main wheel coordinated turning dynamics equation is as follows:

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] where m is the mass of the aircraft, v is the taxiing speed, R is the distance from the instantaneous ground turning center point of the aircraft to the center of gravity, (x, y) are the coordinates of the instantaneous ground turning center point of the aircraft, N n1 ~N n2 are the lateral forces of 2 front wheels, N Mf1 ~N Mf4 are the lateral forces of 4 main wheels on the front axle, N Mm1 ~N Mm4 are the lateral forces of 4 main wheels on the middle axle, N Ma1 ~N Ma4 are the lateral forces of 4 main wheels on the rear axle, T n1 ~T n2 are the rolling frictions of 2 front wheels, T Mf1 ~T Mf4 are the rolling frictions of 4 main wheels on the front axle, T Mm1 ~T Mm4 are the rolling frictions of 4 main wheels on the middle axle, T Ma1 ~T Ma4 are the rolling frictions of 4 main wheels on the rear axle, are the sideslip angles of 2 front wheels, are the sideslip angles of 4 main wheels on the front axle, are the sideslip angles of 4 main wheels on the middle axle, are the sideslip angles of 4 main wheels on the rear axle, α is the front wheel steering angle, β1 is the steering angle of the outer main wheel during turning, and β2 is the steering angle of the inner main wheel during turning.

[0071] The moment balance equation in the aircraft ground main wheel coordinated turning dynamics equation is:

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] f5(α)=(T Ma1 sinβ1 + TMa2 sinβ1 + T Ma3 sinβ2 + T Ma4 sinβ2)L3

[0078]

[0079]

[0080] Wherein, m is the mass of the aircraft, v is the taxiing speed, R is the distance from the instantaneous ground turning center point of the aircraft to the center of gravity, (x, y) is the coordinate of the instantaneous ground turning center point of the aircraft, N n1 ~N n2 are the lateral forces of 2 front wheels, N Mf1 ~N Mf4 are the lateral forces of 4 front axle main wheels, N Mm1 ~N Mm4 are the lateral forces of 4 middle axle main wheels, N Ma1 ~N Ma4 are the lateral forces of 4 rear axle main wheels, T n1 ~T n2 are the rolling frictions of 2 front wheels, T Mf1 ~T Mf4 are the rolling frictions of 4 front axle main wheels, T Mm1 ~T Mm4 are the rolling frictions of 4 middle axle main wheels, T Ma1 ~T Ma4 are the rolling frictions of 4 rear axle main wheels, is the sideslip angle of 2 front wheels, is the sideslip angle of 4 front axle main wheels, is the sideslip angle of 4 middle axle main wheels, is the sideslip angle of 4 rear axle main wheels, α is the front wheel steering angle, dα / dt is the front wheel steering rate, β1 is the turning outer main wheel steering angle, β2 is the turning inner main wheel steering angle, J is the moment of inertia of the aircraft, L is the distance between the front main landing gears, e is the front wheel stability distance, L1 is the distance from the center of gravity of the aircraft to the front axle of the main landing gear, L2 is the distance from the center of gravity of the aircraft to the middle axle of the main landing gear, L3 is the distance from the center of gravity of the aircraft to the rear axle of the main landing gear, L4 is the distance from the center of gravity of the aircraft to the front landing gear, L M is the distance between the two main landing gears, L n is the distance between the two tires of the front landing gear, d M is 1 / 2 of the distance between the coaxial tires of the main landing gear.

[0081] S3. Calculate the sideslip angle of each tire corresponding to different front wheel steering angles according to the relationship between the tire position coordinates and the front wheel rotation angle and the main wheel rotation angle.

[0082] The expression for calculating the sideslip angle is:

[0083]

[0084]

[0085]

[0086]

[0087] In the formula, (x, y) are the coordinates of the instantaneous ground turning center point of the aircraft. i = n1 is the outer tire of the nose landing gear during turning, i = n2 is the inner tire of the nose landing gear during turning, i = f1 is the outer tire of the front axle of the outer main landing gear during turning, i = f2 is the inner tire of the front axle of the outer main landing gear during turning, i = f3 is the outer tire of the front axle of the inner main landing gear during turning, i = f4 is the inner tire of the front axle of the inner main landing gear during turning, i = m1 is the outer tire of the middle axle of the outer main landing gear during turning, i = m2 is the inner tire of the middle axle of the outer main landing gear during turning, i = m3 is the outer tire of the middle axle of the inner main landing gear during turning, i = m4 is the inner tire of the middle axle of the inner main landing gear during turning, i = a1 is the outer tire of the rear axle of the outer main landing gear during turning, i = a2 is the inner tire of the rear axle of the outer main landing gear during turning, i = a3 is the outer tire of the rear axle of the inner main landing gear during turning, i = a4 is the inner tire of the rear axle of the inner main landing gear during turning, α is the front wheel angle, β1 is the turning angle of the outer main wheel, β2 is the turning angle of the inner main wheel, (x i , y i ) are the tire position coordinates.

[0088] S4. Calculate the cornering stiffness of each tire according to the vertical tire load and tire parameters. The tire parameters include tire width, tire diameter, tire pressure, and tire rated pressure.

[0089] The calculation expression of the cornering stiffness is:

[0090]

[0091] In the formula, is the cornering stiffness, w is the tire width, p is the tire pressure, p r is the tire rated pressure, d is the tire diameter, and V′ is the vertical tire load.

[0092] S5. Calculate the dimensionless cornering angle of the tire according to the cornering angle and cornering stiffness, and calculate the lateral force of each tire based on the dimensionless cornering angle of the tire and the vertical tire load.

[0093] The calculation expression of the tire lateral force is:

[0094]

[0095]

[0096] where N i is the lateral force of the tire numbered i, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i, φ i ′ is the dimensionless sideslip angle of the tire numbered i, is the sideslip stiffness of the tire numbered i, is the sideslip angle of the tire numbered i. According to the Magic - Fiala model, the critical dimensionless sideslip angle of the tire is 1.54.

[0097] S6. Based on the critical dimensionless sideslip angle and the lateral forces of each tire, and corrected based on the Magic - Fiala model, the critical lateral force of the tire is obtained. The calculation expression for obtaining the critical lateral force of the tire is:

[0098] [N i = 1.0063μ y V i ′

[0099] where [N i is the critical lateral force of the tire numbered i, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i.

[0100] S7. Determine the sideslip boundary condition of the aircraft with the criterion that the lateral force of each tire does not exceed the critical lateral force.

[0101] The expression for the front wheels not to slip sideways is:

[0102] N i ≤ [N i , i = n1, n2

[0103] The expression for the main wheels not to slip sideways is:

[0104] N i ≤ [N i , i = f1, f2, f3, f4, m1, m2, m3, m4, a1, a2, a3, a4

[0105] where N i is the lateral force of the tire numbered i, [N iThe critical lateral force of the tire numbered i, where i = n1 is the outer tire of the nose landing gear during turning, i = n2 is the inner tire of the nose landing gear during turning, i = f1 is the outer tire of the front axle of the outer main landing gear during turning, i = f2 is the inner tire of the front axle of the outer main landing gear during turning, i = f3 is the outer tire of the front axle of the inner main landing gear during turning, i = f4 is the inner tire of the front axle of the inner main landing gear during turning, i = m1 is the outer tire of the middle axle of the outer main landing gear during turning, i = m2 is the inner tire of the middle axle of the outer main landing gear during turning, i = m3 is the outer tire of the middle axle of the inner main landing gear during turning, i = m4 is the inner tire of the middle axle of the inner main landing gear during turning, i = a1 is the outer tire of the rear axle of the outer main landing gear during turning, i = a2 is the inner tire of the rear axle of the outer main landing gear during turning, i = a3 is the outer tire of the rear axle of the inner main landing gear during turning, and i = a4 is the inner tire of the rear axle of the inner main landing gear during turning.

[0106] S8. According to the sideslip boundary conditions, calculate the critical front-wheel angles at different taxiing speeds, obtain the sideslip safety envelope during coordinated turning of the main wheels, and control the actual front-wheel angle of the aircraft based on the sideslip safety envelope.

[0107] The following is an example for illustration:

[0108] In this example, the schematic diagram of the tire layout of the aircraft landing gear is as shown in Figure 2 The schematic diagram of the forces acting on the aircraft is as shown in Figure 3 The schematic diagram of the tire sideslip angles of the aircraft is as shown in Figure 4 The relationship between the given turning angles of the outer and inner main wheels and the front-wheel angle is as follows:

[0109] The parameters used in the calculation process are shown in the following tables. Table 1 is the position coordinates of each tire, Table 2 is the parameters of the landing gear tires, and Table 3 is the table of aircraft ground turning parameters. The calculated sideslip safety envelope is as shown in

[0110]

[0111] Table 1 Position coordinates of each tire Figure 5 The following is shown.

[0112] Table 1 Position coordinates of each tire

[0113] <![CDATA[(x n1 ,y n1 )]]> <![CDATA[(x n2 ,y n2 )]]> <![CDATA[(x f1 ,y f1 )]]> <![CDATA[(x f2 ,y f2 )]]> (0.1,-0.39) (0.1,0.39) (29.77,-6.185) (29.77,-4.785) <![CDATA[(x f3 ,y f3 )]]> <![CDATA[(x f4 ,y f4 )]]> <![CDATA[(x m1 ,y m1 )]]> <![CDATA[(x m2 ,y m2 )]]> (29.77,4.785) (29.77,6.185) (31.22,-6.185) (31.22,-4.785) <![CDATA[(x m3 ,y m3 )]]> <![CDATA[(x m4 ,y m4 )]]> <![CDATA[(x a1 ,y a1 )]]> <![CDATA[(x a2 ,y a2 )]]> (31.22,4.785) (31.22,6.185) (32.7,-6.185) (32.7,-4.785) <![CDATA[(x a3 ,y a3 )]]> <![CDATA[(x a4 ,y a4 )]]> (32.7,4.785) (32.7,6.185)

[0114] Table 2 Parameters of the landing gear tires

[0115] Tire position Tire width Tire diameter Tire pressure Nose landing gear 0.4445m 1.0922m 1499400 Pa Main landing gear 0.5334m 1.3208m 1499400 Pa

[0116] Table 3 Table of aircraft ground turning parameters

[0117]

[0118] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A method for controlling anti-skid during coordinated turning of aircraft ground main wheels, characterized in that, The method includes the following steps: S1. Obtain the operating conditions of the aircraft and the tire position coordinates, where the operating conditions of the aircraft include the taxiing speed of the aircraft and the corresponding vertical load on the tires; S2. Calculate and determine the instantaneous ground turning center point of the aircraft at different taxiing speeds according to the aircraft ground main wheel coordinated turning dynamics equation and the relationship between the front wheel angle and the main wheel angle under the optimization constraint of the main landing gear force, where the dynamics equation includes the force balance equation and the moment balance equation; S3. Calculate the sideslip angles of each tire corresponding to different front wheel angles according to the tire position coordinates, the instantaneous ground turning center point of the aircraft, and the relationship between the front wheel angle and the main wheel angle; S4. Calculate the sideslip stiffness of each tire according to the vertical load on the tire and the tire parameters; S5. Calculate the dimensionless sideslip angle of the tire according to the sideslip angle and the sideslip stiffness, and calculate the lateral force of each tire based on the dimensionless sideslip angle of the tire and the vertical load on the tire; S6. Based on the critical dimensionless sideslip angle and the lateral force of each tire, and corrected based on the Puck-Fiala model, obtain the critical lateral force of the tire; S7. Determine the sideslip boundary conditions of the aircraft with the criterion that the lateral force of each tire does not exceed the critical lateral force; S8. According to the sideslip boundary conditions, calculate the critical front wheel angles at different taxiing speeds, obtain the sideslip safety envelope during the coordinated turning of the main wheels, and control the actual front wheel angle of the aircraft based on the sideslip safety envelope; The specific expression for calculating the lateral force of each tire based on the dimensionless sideslip angle of the tire and the vertical load on the tire is: N i = (φ i ′ - 0.0668φ i ′ 2 - 0.1032φ i ′ 3 )μ y V i ′ Where, N i is the lateral force of the tire numbered i, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i, φ i ′ is the dimensionless sideslip angle of the tire numbered i.

2. The anti-skid control method for coordinated turning of the main landing gear of an aircraft according to claim 1, characterized in that The vertical load on the tire is obtained based on the vertical load distribution between the nose landing gear and the main landing gear, and the vertical load distribution among the front, middle, and rear axles of the main landing gear. Among them, the calculation expression for the vertical load distribution between the nose landing gear and the main landing gear is: Among them, V1 is the vertical load of the aircraft's nose landing gear, V2 is the vertical load of the outer main landing gear during aircraft turning, V3 is the vertical load of the inner main landing gear during aircraft turning, V is the total vertical load of the aircraft, η is the vertical load distribution ratio of the nose landing gear when the aircraft is static, m is the mass of the aircraft, v is the taxiing speed, R is the distance from the instantaneous ground turning center point of the aircraft to the center of gravity, (x, y) is the coordinate of the instantaneous ground turning center point of the aircraft, L M is the distance between the two main landing gears, and H is the height of the aircraft's center of gravity; The calculation expression for the vertical load distribution among the front, middle, and rear axles of the main landing gear is: Among them, V F is the vertical load on the front axle of the main landing gear of the aircraft, V M is the vertical load on the middle axle of the main landing gear of the aircraft, V A is the vertical load on the rear axle of the main landing gear of the aircraft, L da is the distance between the middle and rear axles of the main landing gear, L df is the distance between the front and middle axles of the main landing gear, μ is the rolling friction coefficient, and h is the distance between the intersection point of the main landing gear support and the buffer strut.

3. The aircraft ground main wheel coordinated turning anti-skid control method according to claim 2, characterized in that, There are 2 coaxial tires on each of the front, middle, and rear axles. For the vertical load on the coaxial tires, it is divided into symmetric distribution and asymmetric distribution cases for distribution.

4. A method for controlling anti-skid during coordinated turning of an aircraft's main landing gear on the ground according to claim 3, characterized in that, In the case of symmetric distribution, the vertical load on the coaxial tires is equally distributed.

5. A method for preventing sideslip control of coordinated turning of aircraft ground main wheels according to claim 3, characterized in that, In the case of asymmetric distribution, the vertical load on the coaxial tires on the paved runway is distributed according to 6:4, and the vertical load on the coaxial tires on the semi-paved or unpaved runway is distributed according to 7:

3.

6. The aircraft ground main wheel collaborative turning anti-skid control method according to claim 1, characterized in that, The specific expression for calculating the dimensionless sideslip angle of the tire according to the sideslip angle and the sideslip stiffness is: Among them, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i, φ i ′ is the dimensionless sideslip angle of the tire numbered i, is the cornering stiffness of the tire numbered i, is the sideslip angle of the tire numbered i.

7. A method for controlling anti-skid during coordinated turning of the main landing gear of an aircraft on the ground, characterized in that, According to the Puck-Fiala model, the critical dimensionless sideslip angle of the tire is 1.

54.

8. A method for preventing side slip in coordinated turning of aircraft ground main wheels according to claim 1, characterized in that The calculation expression for the corrected critical lateral force of the tire is: [N i =1.0063 μ y V i ′ Among them, [N i is the critical lateral force of the tire numbered i, μ y is the lateral friction coefficient, V i ′ is the vertical load of the tire numbered i.

9. A method for controlling anti-skid during coordinated turning of aircraft ground main wheels according to claim 1, characterized in that, The sideslip boundary conditions of the aircraft include the condition that the front wheels do not sideslip and the condition that the main wheels do not sideslip.

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