Method, system and terminal equipment for shimmy stability analysis of a front landing gear

Abstract

The application discloses a front landing gear global shimmy stability analysis method and system, and a terminal device, establishes a front landing gear shimmy dynamics equation, establishes a function relationship between parameters in the shimmy dynamics equation changing with compression and the landing gear compression, substitutes into the shimmy dynamics equation, and forms the shimmy dynamics equation containing the front landing gear compression and the taxiing speed. The shimmy frequency and the damping ratio are solved through the characteristic root of the dynamics equation when the compression and the taxiing speed are fixed and unchanged, the shimmy frequency and the damping ratio under all combinations of the taxiing speed and the compression are plotted contour lines, and the shimmy frequency and the stability result of the front landing gear global are obtained. The application converts multiple parameters into the function of the compression, realizes the evaluation of the landing gear stability under any combination of the buffer compression and the taxiing speed from the perspective of the characteristic root of the shimmy equation, and avoids the shortcoming that the response curve is not comprehensive in the evaluation of the stability when the shimmy dynamics equation of different compressions is established.

Description

Technical Field

[0001] This invention relates to the field of aircraft landing gear shimmy dynamics analysis, and in particular to a method, system and terminal equipment for analyzing the shimmy stability of the entire nose landing gear. Background Technology

[0002] Stability analysis of nose landing gear shimmy is a crucial part of landing gear dynamics analysis. Shimmy refers to a severe swaying phenomenon that occurs during takeoff or landing, where the nose wheel deviates from its neutral position. This severely impacts passenger comfort, aircraft handling, and can cause damage to the airframe and landing gear, seriously jeopardizing aircraft safety. Shimmy is a self-excited vibration of the landing gear, therefore, dampers must be installed on the landing gear. These dampers absorb energy through hydraulic damping to prevent shimmy. Shimmy stability analysis typically involves two aspects: First, calculating the critical damping by establishing the shimmy dynamics equations. Critical damping refers to the minimum damping required to prevent shimmy divergence, and its calculation provides guidance for damper design. Second, verifying the damper's designed damping value by determining whether the landing gear sway response curve meets the requirement of rapid convergence under a given initial disturbance.

[0003] Current stability analysis of design damping values ​​typically involves selecting several combinations of landing gear compression and runway speed, calculating the shimmy response curve under an initial disturbance, judging landing gear stability based on the convergence of the response curve, and obtaining the shimmy frequency through spectral analysis of the response curve. This method requires establishing the shimmy dynamic equations and solving the response curves for different landing gear compressions. It can only analyze shimmy stability under limited combinations of compression and runway speed, and the calculation process is complex and time-consuming, failing to quickly obtain the stability results and shimmy frequency for the entire nose landing gear compression and all runway speed combinations. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method, system and terminal equipment for analyzing the shimmy stability of the entire nose landing gear, which can quickly obtain the stability results and shimmy frequency of the entire nose landing gear compression and all combinations of taxiing speeds, in order to address the shortcomings of the existing technology.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for analyzing the shimmy stability of the entire nose landing gear, comprising the following steps:

[0006] S1. Establish the dynamic equations for the nose landing gear oscillation;

[0007] S2. For the parameters in the oscillation dynamic equation that vary with the landing gear compression, establish a functional relationship between the parameters and the landing gear compression h based on the variation law of the parameters with the compression.

[0008] S3. Substitute the functional relationship between each parameter and the landing gear compression h into the aforementioned nose landing gear shimmy dynamic equation to obtain a shimmy dynamic equation that includes the relationship between the landing gear compression and the runway speed.

[0009] S4. Calculate the shimmy frequency and damping ratio of all landing gear compression and runway speed combinations. Plot contour lines with runway speed as the x-axis and landing gear compression as the y-axis to obtain the shimmy frequency and stability results of the entire front landing gear.

[0010] This invention transforms the shimmy dynamics equation containing multiple parameters into an equation containing landing gear compression and runway speed. By solving the eigenvalues ​​of the equation to determine the shimmy frequency and damping ratio, it achieves global stability analysis and calculation of the shimmy frequency. Since the method of this invention does not require the establishment of shimmy dynamics equations and response curves for different landing gear compression, it can analyze the shimmy stability under the combination of compression and runway speed across the entire range. Furthermore, the calculation process is simple, fast, and time-efficient.

[0011] In step S1 of the present invention, the expression for the dynamic equation of the nose landing gear oscillation is:

[0012]

[0013] Where Ψ is the lateral rotation angle of the landing gear about the X-axis. Let be the lateral rotational angular velocity of the landing gear about the X-axis. Let θ be the lateral rotational angular acceleration of the landing gear about the X-axis, and θ be the yaw angle of the wheels about the Y-axis. Let be the angular velocity of the wheel's oscillation around the Y-axis. Let θ be the angular acceleration of the wheel about the Y-axis, and θ1 be the rotation angle about the Y-axis at the damper. Let be the rotational angular velocity about the Y-axis at the oscillator. Let ω be the angular acceleration about the Y-axis at the damper, and λ be the lateral deformation of the tire. The lateral deformation rate of the tire. This refers to the lateral deformation acceleration of the tire. The torsion angle of the tire. The torsional angular velocity of the tire. Let i be the torsional angular acceleration of the tire, i be the moment of inertia of the wheel about its own axis, r be the tire radius, d be half the wheelbase, Lt be the stabilizer distance, Ct be the landing gear sway damping coefficient, n be the number of wheels, v be the aircraft's takeoff speed, and I be the landing gear sway damping coefficient. x Let I be the moment of inertia of the landing gear about the X-axis. y Let I be the moment of inertia of the landing gear about the Y-axis. xy Let H be the moment of inertia of the landing gear due to bending and torsional coupling, and H be the vertical distance from the landing gear mounting point to the wheel axle. S For the lateral stiffness of the landing gear, KT For the torsional stiffness of the landing gear, K γ K represents the radial stiffness of the tire. λ For tire lateral stiffness, Let α be the tire torsional stiffness, β be the tire lateral rolling coefficient, γ be the tire torsional rolling coefficient, and Fy be the landing gear vertical load. The landing gear moves along the X-axis, with forward being positive. The Z-axis points to the right of the direction of movement, and the Y-axis is determined according to the right-hand rule.

[0014] In step S2 of the present invention, the functional relationship between each parameter and the landing gear compression amount h is expressed as follows:

[0015] Moment of inertia I of landing gear about the X-axis x (h): I x (h)=a 11 h 2 +a 12 h+a 13 ;

[0016] The moment of inertia of the landing gear about the Y-axis I y (h): I y (h)=a 21 h 2 +a 22 h+a 23 ;

[0017] Landing gear bending-torsional coupling moment of inertia I xy (h): I xy (h)=a 31 h 2 +a 32 h+a 33 ;

[0018] The vertical distance H(h) from the landing gear mounting point to the wheel axle: H(h) = a 41 h 2 +a 42 h+a 43 ;

[0019] Landing gear lateral stiffness K S (h): K S (h)=a 51 h 2 +a 52 h+a 53 ;

[0020] Landing gear torsional stiffness K T (h): K T (h)=a 61 h 2 +a 62 h+a 63 ;

[0021] Tire radial stiffness K γ (h): K γ (h)=a 71 e a72h +a 73 ;

[0022] Tire lateral stiffness K λ (h): K λ (h)=a 81 e a82h +a 83 ;

[0023] Tire torsional stiffness

[0024] Tire lateral rolling coefficient α(h): α(h) = a 101 h 2 +a 102 h+a 103 ;

[0025] Tire torsional rolling coefficient β(h): β(h) = a 111 h 2 +a 112 h+a 113 ;

[0026] Tire roll coefficient γ(h): γ(h) = a 121 h 2 +a 122 h+a 123 ;

[0027] Landing gear vertical load F y (h): F y (h)=a 131 h 2 +a 132 h+a 133 ;

[0028] Among them, a s1 a s2 a s3 For constant coefficients, s = 1, 2, ..., 13. The values ​​of the above parameters under different landing gear compressions are obtained through experiments or simulations. The value of 'a' is then determined using polynomial fitting or exponential fitting. s1 a s2 a s3 .

[0029] In step S3, the expression for the shimmy dynamics equation, which includes the relationship between landing gear compression and runway speed, is as follows:

[0030]

[0031] In step S4, the process of calculating the shimmy frequency and damping ratio of all landing gear compression and runway speed combinations includes: simplifying the shimmy dynamic equation, which includes the relationship between landing gear compression and runway speed, into the following expression:

[0032]

[0033]

[0034]

[0035]

[0036] Given a set of compression values ​​and gliding speeds, calculate the eigenvalues ​​λ of the simplified expression: λ = -a ± bj; a and b are the real and imaginary parts of the eigenvalues, respectively.

[0037] The oscillation frequency f and damping ratio ξ are calculated using the characteristic root λ:

[0038] In step S4, when the damping ratio is greater than zero, the nose landing gear is determined to be globally stable and the sway response curve converges; when the damping ratio is less than zero, the nose landing gear is determined to be globally unstable and the sway response curve diverges.

[0039] As an inventive concept, the present invention also provides a system for analyzing the shimmy stability of the entire nose landing gear, comprising:

[0040] The first modeling unit is used to establish the dynamic equations for the nose landing gear oscillation.

[0041] The second modeling unit is used to establish the functional relationship between the parameters and the landing gear compression h based on the variation law of the parameters in the oscillation dynamic equation that vary with the landing gear compression.

[0042] The third modeling unit is used to substitute the functional relationship between each parameter and the landing gear compression h into the front landing gear shimmy dynamic equation to obtain the shimmy dynamic equation that includes the landing gear compression and the runway speed.

[0043] The stability analysis unit is used to calculate the shimmy frequency and damping ratio of all landing gear compression and runway speed combinations. With runway speed as the abscissa and landing gear compression as the ordinate, contour lines are drawn to obtain the shimmy frequency and stability results of the entire nose landing gear.

[0044] As an inventive concept, the present invention also provides a terminal device, including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program to implement the steps of the stability analysis method described above.

[0045] As an inventive concept, the present invention also provides a computer-readable storage medium having a computer program / instructions stored thereon; when the computer program / instructions are executed by a processor, they implement the steps of the stability analysis method described above.

[0046] As an inventive concept, the present invention also provides a computer program product, including a computer program / instructions; when the computer program / instructions are executed by a processor, they implement the steps of the stability analysis method described above.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. This invention transforms multiple parameters of the shimmy dynamics equation into functions of compression, and evaluates the stability of the landing gear under any combination of buffer compression and runway speed from the perspective of the characteristic roots of the shimmy equation. This avoids the drawback of establishing shimmy dynamics equations with different compressions to solve response curves and evaluate stability in a comprehensive manner. It is applicable to the shimmy stability analysis of aircraft nose landing gear.

[0049] 2. The calculation process of this invention is simple and time-saving, which greatly improves the efficiency of oscillation analysis. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the landing gear structure;

[0051] Figure 2 This is a schematic diagram of the geometric relationship of a rolling tire;

[0052] Figure 3 This is a schematic diagram of the global oscillation frequency of the landing gear according to an embodiment of the present invention;

[0053] Figure 4 This is a schematic diagram of the global damping ratio of the landing gear in an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] In this paper, the terms "contains," "includes," and similar words are intended to indicate logical relationships, not spatial relationships. For example, "A includes B" means that logically B belongs to A, not that spatially B is located inside A. Furthermore, the meanings of the terms "contains," "includes," and similar words should be considered open-ended, not closed-ended. For example, "A includes B" means that B belongs to A, but B does not necessarily constitute the entirety of A; A may also include other elements such as C, D, and E.

[0056] Example 1

[0057] This embodiment provides a method for analyzing the shimmy stability of the entire nose landing gear, including the following steps:

[0058] Step 1: Establish the dynamic equation for the nose landing gear oscillation, as shown in equation (1). The landing gear moves along the X-axis (distance S), with forward being positive. The Z-axis points to the right of the direction of motion. The Y-axis is determined according to the right-hand rule. The physical meaning of each parameter in the equation is shown in [reference needed]. Figure 1 and Figure 2 As shown.

[0059]

[0060] In the equation, the degrees of freedom of motion for the pendulum equation are:

[0061] Ψ—Lateral rotation angle of the landing gear around the X-axis;

[0062] θ — the oscillation angle of the wheel about the Y-axis;

[0063] θ1—The rotation angle about the Y-axis at the gyroscope damper;

[0064] λ—lateral deformation of the tire;

[0065] —Tire torsion angle;

[0066] The parameter that does not change with landing gear compression is:

[0067] i—moment of inertia of the wheel about its own axis;

[0068] r—tire radius;

[0069] d—half of the wheel track;

[0070] Lt—Stability distance;

[0071] Ct—Landing gear anti-sway damping coefficient;

[0072] n—Number of wheels;

[0073] v—Aircraft taxiing speed;

[0074] The parameters that vary with landing gear compression are:

[0075] I x —Moment of inertia of the landing gear about the X-axis;

[0076] I y —Moment of inertia of the landing gear about the Y-axis;

[0077] I xy —Landing gear bending-torsional coupling moment of inertia;

[0078] H—the vertical distance from the landing gear mounting point to the wheel axle;

[0079] K S —Landing gear lateral stiffness;

[0080] K T —Landing gear torsional stiffness;

[0081] K γ —Tire radial stiffness;

[0082] K λ —Tire lateral stiffness;

[0083] —Tire torsional stiffness;

[0084] α—Tire lateral rolling coefficient;

[0085] β—Tire torsional rolling coefficient;

[0086] γ—Tire roll coefficient;

[0087] Fy — Landing gear vertical load.

[0088] Step two: For the parameters in the oscillation dynamics equation that vary with the landing gear compression, establish the functional relationship between these parameters and the landing gear compression h based on the variation law of the parameters with the compression, as follows:

[0089] Moment of inertia of the landing gear about the X-axis:

[0090] I x (h)=a 11 h 2 +a 12 h+a 13 (2)

[0091] Moment of inertia of the landing gear about the Y-axis:

[0092] I y (h)=a 21 h 2 +a 22 h+a 23 (3)

[0093] Landing gear bending-torsional coupling moment of inertia:

[0094] I xy (h)=a 31 h 2 +a 32 h+a 33 (4)

[0095] Vertical distance from landing gear mounting point to wheel axle:

[0096] H(h)=a 41 h 2 +a 42 h+a 43 (5)

[0097] Landing gear lateral stiffness:

[0098] K S (h)=a 51 h 2 +a 52 h+a 53 (6)

[0099] Landing gear torsional stiffness:

[0100] K T (h)=a 61 h 2 +a 62 h+a 63 (7)

[0101] Tire radial stiffness:

[0102]

[0103] Tire lateral stiffness:

[0104]

[0105] Tire torsional stiffness:

[0106]

[0107] Tire lateral rolling coefficient;

[0108] α(h)=a 101 h 2 +a 102 h+a 103 (11)

[0109] Tire torsional rolling coefficient;

[0110] β(h)=a 111 h 2+a 112 h+a 113 (12)

[0111] Tire roll coefficient;

[0112] γ(h)=a 121 h 2 +a 122 h+a 123 (13)

[0113] Vertical load on landing gear.

[0114] F y (h)=a 131 h 2 +a 132 h+a 133 (14)

[0115] Step 3: Substitute the functional relationships between the parameters and the compression amount obtained in Step 2, i.e., equations (2) to (14), into the oscillation dynamic equation established in Step 1 to obtain the oscillation dynamic equation that includes the relationship between the landing gear compression amount and the running speed, as shown in equation (15).

[0116]

[0117] The equation can be simplified as follows:

[0118]

[0119] in:

[0120]

[0121]

[0122]

[0123]

[0124] Step 4: Given a set of compression and gliding speed, solve for the characteristic roots of equation (16). The characteristic roots can be expressed as:

[0125] λ=-a±bj(21)

[0126] The system's oscillation frequency is:

[0127]

[0128] The oscillation frequency f represents the number of oscillations of the landing gear in one cycle.

[0129] The damping ratio is:

[0130]

[0131] A damping ratio greater than zero indicates that the system is stable and the oscillation response curve converges; the larger the damping ratio, the greater the safety margin. A damping ratio less than zero indicates that the system is unstable and the oscillation response curve diverges.

[0132] Step 5: Solve for the oscillation frequency and damping ratio of all combinations of compression and takeoff speed. Plot contour lines with takeoff speed on the x-axis and landing gear compression on the y-axis, as shown below. Figure 3 and Figure 4 As shown, the oscillation frequency and stability results of the entire front landing gear can be obtained.

[0133] Example 2

[0134] This embodiment provides a system for analyzing the shimmy stability of the entire nose landing gear, which includes:

[0135] The first modeling unit is used to establish the dynamic equations for the nose landing gear oscillation.

[0136] The second modeling unit is used to establish the functional relationship between the parameters and the landing gear compression h based on the variation law of the parameters in the oscillation dynamic equation that vary with the landing gear compression.

[0137] The third modeling unit is used to substitute the functional relationship between each parameter and the landing gear compression h into the front landing gear shimmy dynamic equation to obtain the shimmy dynamic equation that includes the landing gear compression and the runway speed.

[0138] The stability analysis unit is used to calculate the shimmy frequency and damping ratio of all landing gear compression and runway speed combinations. With runway speed as the abscissa and landing gear compression as the ordinate, contour lines are drawn to obtain the shimmy frequency and stability results of the entire nose landing gear.

[0139] The calculation process involved in each of the above units is the same as that in Example 1, and will not be repeated here.

[0140] Example 3

[0141] Embodiment 3 of the present invention provides a terminal device corresponding to Embodiment 1 above. The terminal device can be a processing device for a client, such as a mobile phone, a laptop, a tablet computer, a desktop computer, etc., to execute the method of the above embodiments.

[0142] The terminal device in this embodiment includes a memory, a processor, and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method in Embodiment 1 described above.

[0143] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0144] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0145] Example 4

[0146] Embodiment 4 of the present invention provides a computer-readable storage medium corresponding to Embodiment 1 above, on which a computer program / instructions are stored. When the computer program / instructions are executed by a processor, they implement the steps of the method of Embodiment 1 above.

[0147] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0148] Example 5

[0149] Embodiment 5 of the present invention provides a computer program product corresponding to Embodiment 1 above, which includes a computer program / instructions; when the computer program / instructions are executed by a processor, they implement the steps of the method of Embodiment 1.

[0150] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0151] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0152] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0153] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0154] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method of analyzing shimmy stability of a front landing gear over a whole region, characterized by, Includes the following steps: S1. Establish the dynamic equations for the nose landing gear oscillation; S2. For the parameters in the oscillation dynamic equation that vary with the landing gear compression, establish a functional relationship between the parameters and the landing gear compression h based on the variation law of the parameters with the compression. S3. Substitute the functional relationship between each parameter and the landing gear compression h into the aforementioned nose landing gear shimmy dynamic equation to obtain a shimmy dynamic equation that includes the relationship between the landing gear compression and the runway speed. S4. Calculate the shimmy frequency and damping ratio of all landing gear compression and takeoff speed combinations. Plot contour lines with takeoff speed as the x-axis and landing gear compression as the y-axis to obtain the shimmy frequency and stability results of the entire front landing gear. In step S1, the expression for the dynamic equation of the nose landing gear oscillation is: ； Where Ψ is the lateral rotation angle of the landing gear about the X-axis. Let be the lateral rotational angular velocity of the landing gear about the X-axis. Let θ be the lateral rotational angular acceleration of the landing gear about the X-axis, and θ be the yaw angle of the wheels about the Y-axis. Let be the angular velocity of the wheel's oscillation around the Y-axis. Let θ be the angular acceleration of the wheel about the Y-axis, and θ1 be the rotation angle about the Y-axis at the damper. Let ω be the angular velocity of rotation about the Y-axis at the damper, and λ be the lateral deformation of the tire. The lateral deformation rate of the tire. Let φ be the lateral deformation acceleration of the tire, and φ be the torsional angle of the tire. The torsional angular velocity of the tire. Let θ be the torsional angular acceleration of the tire, i be the moment of inertia of the wheel about its own axis, r be the tire radius, d be half the wheelbase, and L be the radius of the tire. t For the steady moment, C t The landing gear damping coefficient is given by n, where n is the number of wheels, v is the aircraft's takeoff speed, and I is the landing gear damping coefficient. x Let I be the moment of inertia of the landing gear about the X-axis. y Let I be the moment of inertia of the landing gear about the Y-axis. xy Let H be the moment of inertia of the landing gear due to bending and torsional coupling, and H be the vertical distance from the landing gear mounting point to the wheel axle. S For the lateral stiffness of the landing gear, K T For the torsional stiffness of the landing gear, K γ K represents the radial stiffness of the tire. λ K represents the lateral stiffness of the tire. φ Let F be the tire torsional stiffness, α be the tire lateral rolling coefficient, β be the tire torsional rolling coefficient, and γ be the tire roll rolling coefficient. y The vertical load is the landing gear load; the landing gear moves along the X-axis, with forward being positive, the Z-axis points to the right of the direction of movement, and the Y-axis is determined according to the right-hand rule.

2. The method for analyzing the shimmy stability of the entire nose landing gear according to claim 1, characterized in that, In step S2, the functional relationship between each parameter and the landing gear compression h is expressed as follows: Rolling moment of inertia of the landing gear about the x axis : ; Rolling moment of inertia of the landing gear about the Y axis : ; Landing gear bending-torsion coupled moment of inertia : ; Vertical distance from landing gear mounting point to wheel axle : ; Landing gear lateral stiffness : ; Landing gear torsional stiffness : ; Tire radial stiffness : ; Tire lateral stiffness : ; Tire torsional stiffness : ; Tire lateral rolling coefficient : ; Tire torsional rolling coefficient : ; Tire cornering force coefficient : ; Landing gear vertical load : ; wherein , , are constant coefficients, s = 1, 2,..., 13.

3. The method of global shimmy stability analysis of a front landing gear according to claim 2, characterized in that, In step S3, the expression for the shimmy dynamics equation, which includes the relationship between landing gear compression and runway speed, is as follows: 。 4. The method for analyzing the shimmy stability of the entire nose landing gear according to claim 2 or 3, characterized in that, Step S4, which calculates the oscillation frequency and damping ratio of all landing gear compression and runway speed combinations, includes: The simplified expression of the shimmy dynamics equation, which includes the relationship between landing gear compression and runway speed, is as follows: ； ； ； ； ； ； Given a set of compression amounts and slide speeds, calculating eigenvalues of the simplified expression : ; a, b are real and imaginary parts of the eigenvalue, respectively Using the eigenvalues Calculating the frequency of the pendulum f and the damping ratio : ; .

5. The method of global shimmy stability analysis of a nose landing gear according to claim 1, wherein In step S4, when the damping ratio is greater than zero, the nose landing gear is determined to be globally stable and the sway response curve converges; when the damping ratio is less than zero, the nose landing gear is determined to be globally unstable and the sway response curve diverges.

6. A system for analyzing the shimmy stability of the entire nose landing gear, characterized in that, include: The first modeling unit is used to establish the dynamic equations for the nose landing gear oscillation. The second modeling unit is used to establish the functional relationship between the parameters and the landing gear compression h based on the variation law of the parameters in the oscillation dynamic equation that vary with the landing gear compression. The third modeling unit is used to substitute the functional relationship between each parameter and the landing gear compression h into the front landing gear shimmy dynamic equation to obtain the shimmy dynamic equation that includes the landing gear compression and the runway speed. The stability analysis unit is used to calculate the shimmy frequency and damping ratio of all combinations of landing gear compression and takeoff speed. With takeoff speed as the abscissa and landing gear compression as the ordinate, contour lines are drawn to obtain the shimmy frequency and stability results of the entire front landing gear. The expression for the dynamic equation of the nose landing gear shimmy is: ； Where Ψ is the lateral rotation angle of the landing gear about the X-axis. Let be the lateral rotational angular velocity of the landing gear about the X-axis. Let θ be the lateral rotational angular acceleration of the landing gear about the X-axis, and θ be the yaw angle of the wheels about the Y-axis. Let be the angular velocity of the wheel's oscillation around the Y-axis. Let θ be the angular acceleration of the wheel about the Y-axis, and θ1 be the rotation angle about the Y-axis at the damper. Let ω be the angular velocity of rotation about the Y-axis at the damper, and λ be the lateral deformation of the tire. The lateral deformation rate of the tire. Let φ be the lateral deformation acceleration of the tire, and φ be the torsional angle of the tire. The torsional angular velocity of the tire. Let θ be the torsional angular acceleration of the tire, i be the moment of inertia of the wheel about its own axis, r be the tire radius, d be half the wheelbase, and L be the radius of the tire. t For the steady moment, C t The landing gear damping coefficient is given by n, where n is the number of wheels, v is the aircraft's takeoff speed, and I is the landing gear damping coefficient. x Let I be the moment of inertia of the landing gear about the X-axis. y Let I be the moment of inertia of the landing gear about the Y-axis. xy Let H be the moment of inertia of the landing gear due to bending and torsional coupling, and H be the vertical distance from the landing gear mounting point to the wheel axle. S For the lateral stiffness of the landing gear, K T For the torsional stiffness of the landing gear, K γ K represents the radial stiffness of the tire. λ K represents the lateral stiffness of the tire. φ Let F be the tire torsional stiffness, α be the tire lateral rolling coefficient, β be the tire torsional rolling coefficient, and γ be the tire roll rolling coefficient. y The vertical load is the landing gear load; the landing gear moves along the X-axis, with forward being positive, the Z-axis points to the right of the direction of movement, and the Y-axis is determined according to the right-hand rule.

7. A terminal device comprising a memory, a processor, and a computer program stored on the memory; characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program / instructions stored thereon; characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 5.

9. A computer program product comprising computer programs / instructions; characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the method described in any one of claims 1 to 5.

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