Calculation method of energy absorption efficiency of aircraft buffer system based on flight test data

Abstract

This invention belongs to the field of flight testing technology, specifically relating to a method for calculating the energy absorption efficiency of an aircraft buffer system based on flight test data, particularly for aircraft with landing gear as the buffer system. The method includes: conducting load calibration tests on the landing gear to obtain test data; determining the coefficients of the load measurement model based on the test data; inputting the measured data into the load measurement model to obtain the measured external load; projecting the measured external load onto a ground coordinate system based on the aircraft's attitude angles to obtain the measured load in the ground coordinate system; inputting the measured sensor positions, aircraft attitude, and initial sensor installation positions into a coordinate transformation matrix to obtain the position of the aircraft's center of gravity in the ground coordinate system; integrating the measured load in the ground coordinate system and the position of the aircraft's center of gravity in the ground coordinate system to obtain the energy absorbed by the aircraft buffer system, and calculating the energy absorption efficiency.

Description

Technical Field

[0001] This invention belongs to the field of flight test technology, specifically relating to a method for calculating the energy absorption efficiency of an aircraft buffer system based on flight test data, and specifically relating to a method for calculating the energy absorption efficiency of an aircraft landing gear buffer system, particularly relating to calculating the energy absorbed by the buffer system and the energy absorption efficiency of the buffer system based on measured flight loads, aircraft position and attitude parameters during flight tests. Background Technology

[0002] The aircraft landing gear is the most important cushioning component during takeoff and landing. By absorbing the impact energy during takeoff and landing, it cushions the impact from the ground, making the takeoff and landing process smoother. At the same time, it reduces the landing load to reduce the structural weight of the aircraft, ensuring structural safety and making the aircraft more economical and practical.

[0003] Currently, the cushioning effect of landing gear is mainly verified through ground drop tests, which calculate the energy absorption efficiency by measuring the energy absorbed by the landing gear during a drop. However, drop tests cannot realistically simulate the horizontal speed of an aircraft and the support stiffness of the landing gear, resulting in discrepancies between the verified cushioning performance and real-world conditions.

[0004] How to calculate the energy absorption efficiency of an aircraft landing gear buffer system using measured flight data, in order to verify and evaluate the buffering capacity of the aircraft landing gear buffer system under real installation and real usage conditions. Summary of the Invention

[0005] Purpose of the invention: To provide a method for calculating the energy absorption efficiency of an aircraft landing gear buffer system based on flight test data. This method calculates the energy absorbed by the aircraft landing gear buffer system and its energy absorption efficiency using flight test data, providing support for evaluating the landing gear buffer performance through flight test data.

[0006] The technical solution of this invention is:

[0007] A method for calculating the energy absorption efficiency of an aircraft buffer system based on flight test data, the method being used to calculate the energy absorption efficiency of an aircraft buffer system under real flight conditions, the method comprising the following steps:

[0008] The landing gear is subjected to load calibration tests to obtain test data, and the coefficients of the load measurement model are determined based on the test data;

[0009] The measured data is input into the load model to obtain the measured external load. The measured external load is then projected onto the ground coordinate system according to the aircraft's attitude angle to obtain the measured load in the ground coordinate system.

[0010] By inputting the measured sensor position, aircraft attitude, and initial sensor installation position into the coordinate transformation matrix, the position of the aircraft's center of gravity in the ground coordinate system can be obtained.

[0011] By integrating the measured load in the ground coordinate system and the position of the aircraft's center of gravity in the ground coordinate system, the energy absorbed by the aircraft's buffer system is obtained, and the energy absorption efficiency is calculated.

[0012] Furthermore, load calibration tests are conducted on the landing gear to obtain test data. Based on the test data, the coefficients of the load measurement model are determined, including:

[0013] Step 1: Install multiple load strain gauges on the main force transmission channel of the landing gear structure;

[0014] Step 2: Load Calibration Test: After the landing gear is installed and fixed, under the fixed stroke of the buffer, apply unidirectional loading in the vertical, yaw, and lateral directions, as well as combined bidirectional and tridirectional loads. Record the load and structural strain data simultaneously during the test. Unidirectional loading in each direction is required, as are combined bidirectional and tridirectional loads. The fixed stroke of the buffer must include at least three sections, named s1, s2, and s3 in sequence. <s2<s3;

[0015] Step 3: Input the applied load and the measured structural strain data from the load strain gauge for each stroke into the load measurement model, and obtain the coefficients of the load measurement model through linear regression; the coefficients of the load measurement model for other strokes are obtained through linear interpolation.

[0016] The load testing model is:

[0017] F J =Kε ​​(1)

[0018] The linear regression solution formula for the load model coefficients is as follows:

[0019] K = F J (εε T ) -1 (2)

[0020] In equations (1) and (2): F J ε represents the applied load for the load calibration test; K is the load measurement model coefficient; ε is the structural strain measured by the load measurement strain gauge.

[0021] Other itineraries: Itineraries that are not any of s1, s2, or s3;

[0022] Formula for the difference of load model coefficients for other strokes:

[0023]

[0024] In equation (3): s is the buffer stroke; K sFor the load model coefficient of the stroke s; These are the load model coefficients for strokes s1, s2, and s3, respectively.

[0025] Furthermore, the measured data is input into the load model to obtain the measured external load. Based on the aircraft's attitude angles, the measured external load is projected onto the ground coordinate system to obtain the measured load in the ground coordinate system, including:

[0026] Step 4: Before the flight test, install GPS or GNS to measure three-dimensional position and three-dimensional velocity, and inertial navigation system to measure three-dimensional attitude on the aircraft; in addition to the strain gauges installed in Step 1, buffer displacement sensors should also be installed on the landing gear; at the same time, test equipment for measuring and recording these parameters should be installed on the aircraft.

[0027] Step 5: Flight Test: Conduct a landing test flight with a high descent speed, requiring the pilot to maneuver the aircraft to land at the required descent speed; during the test, the test equipment collects and records flight data;

[0028] Step 6: Flight Load Calculation: Input the structural strain data and buffer travel data from the measured flight data in Step 5 into the load model in Step 3 to obtain the measured flight load F. F ;

[0029] F F It is a column vector, formed by the measured heading load F. x Lateral load F y and vertical load F z composition:

[0030]

[0031] Step 7: Convert the measured load to a ground coordinate system: Substitute the measured load and aircraft attitude into the conversion formula between the body coordinate system and the ground coordinate system:

[0032] The conversion formula between the body coordinate system and the ground coordinate system is as follows:

[0033]

[0034] P D It is a column vector, composed of three loads in the ground coordinate system, namely the heading load P. x Lateral load P y and vertical load P z composition:

[0035]

[0036] In equation (5), L T-DThe transformation matrix from the aircraft body-axis coordinate system to the ground coordinate system is calculated using the following formula:

[0037]

[0038] In equation (6): θ is the aircraft's yaw angle, θ is the aircraft's pitch angle, and φ is the aircraft's roll angle, which are measured by attitude sensors such as gyroscopes on the aircraft.

[0039] Furthermore, by inputting the measured sensor position, aircraft attitude, and initial sensor installation position into the coordinate transformation matrix, the position of the aircraft's center of gravity in ground coordinates is obtained, including:

[0040] Step 8: Calculate the initial installation angle of the sensor: Obtain the installation position of the GNS position sensor in the body coordinate system as [x cgq_T y cgq_T z cgq_T ] T The initial installation angle of the sensor is calculated from the installation location;

[0041] The formula for calculating the initial installation angle is:

[0042]

[0043]

[0044] In the formula: θ0 is the initial installation yaw angle of the sensor, and θ0 is the initial installation pitch angle of the sensor; x cgq_ T, y cgq_ T and z cgq_T These are the heading, lateral, and vertical mounting positions of the position sensor in the body coordinate system;

[0045] Step 9: Calculate the sensor coordinate transformation matrix: Substitute the initial installation angle of the sensor in Step 8 and the aircraft attitude angle in the measured flight data in Step 5 into the position coordinate transformation matrix. The position coordinate transformation matrix is ​​the transformation matrix from the aircraft body axis coordinates to the ground coordinate system, taking into account the sensor installation position.

[0046] Formula for calculating the position coordinate transformation matrix:

[0047]

[0048] Step 10: Obtain the height of the aircraft's center of gravity relative to the ground: Substitute the position sensor data from the flight data measured in Step 5 and the position coordinate transformation matrix from Step 9 into the center of gravity height calculation formula to obtain the center of gravity height.

[0049] Formula for calculating center of gravity height:

[0050]

[0051] In the formula: z cg x is the height of the aircraft's center of gravity. cgq_T y cgq_T and z cgq_T These are the heading, lateral, and vertical mounting positions of the position sensor in the body coordinate system, L. T_D_str (3,all) is the third row of the position coordinate transformation matrix in step 9.

[0052] Furthermore, by integrating the measured load in the ground coordinate system and the position of the aircraft's center of gravity in the ground coordinate system, the energy absorbed by the aircraft's buffer system is obtained, and the energy absorption efficiency is calculated, including:

[0053] Step 11: Calculate the energy absorbed by the buffer system during aircraft landing: Apply the vertical load data P from Step 7. z And the center of gravity height data z from step 10 cg Perform discrete integration to obtain the energy absorbed by the buffer system;

[0054] Discrete integral formula:

[0055]

[0056] In the formula: A c P is the energy absorbed by the buffer system. Z_i and P Z_i+1 Let z be the vertical load on the landing gear at sampling points i and i+1. cg_i and z cg_i+1 Let i be the height of the aircraft's center of gravity at sampling point i.

[0057] Step 12: Calculate the maximum vertical load P measured during the aircraft landing process in Step 7. z_max z and the maximum vertical height of the center of gravity cg_max ;

[0058] Step 13: Energy absorption efficiency of the buffer system: Substitute the energy absorbed by the buffer system in step 11 and the energy absorbed in step 12 into the formula for calculating the efficiency of the buffer system;

[0059] Formula for calculating the efficiency of a buffer system:

[0060]

[0061] In the formula: η is the efficiency of the buffer system.

[0062] Furthermore, the main force transmission channel in step 1 includes at least the wheel axle, piston rod, outer cylinder, and support rod.

[0063] Furthermore, in step 1, strain gauges sensitive to vertical, yaw, and lateral loads of the landing gear are installed on the wheel axle; strain gauges sensitive to vertical and yaw loads of the landing gear are installed on the piston rod; strain gauges sensitive to yaw and lateral loads of the landing gear are installed on the outer cylinder; and strain gauges sensitive to yaw loads of the landing gear are installed on the strut.

[0064] Furthermore, during the flight test, the sampling frequency of the test parameters was no less than 128 Hz.

[0065] Furthermore, in step 4, sensors for measuring three-dimensional position, three-dimensional velocity, and three-dimensional attitude are installed on the aircraft.

[0066] Furthermore, in step 4, the measured load in the ground coordinate system and the position of the aircraft's center of gravity in the ground coordinate system are integrated to obtain the energy absorbed by the aircraft's buffer system.

[0067] The beneficial effects of this application are as follows:

[0068] (1) Compared with the previous calculation and evaluation of buffer energy absorption efficiency based on laboratory drop data, this method calculates the energy absorption efficiency of the buffer system based on the measured data of the aircraft under real flight conditions. The calculated results reflect the performance of the buffer system under real conditions and have unparalleled authenticity.

[0069] (2) Compared with the previous calculation of buffer energy absorption efficiency based on laboratory drop test data, this method provides a method for calculating buffer energy based on flight test data. This method can not only evaluate the performance of the aircraft buffer system, but also compare it with the drop test, providing direction for the optimization of the drop test. Attached Figure Description

[0070] Figure 1 This is a flowchart of the method described in this invention;

[0071] Figure 2 This is a curve showing the vertical load and center of gravity height in the ground coordinate system. Detailed Implementation

[0072] This invention relates to a method for calculating the energy absorption efficiency of a landing gear buffer system based on flight test data, belonging to the field of flight testing technology. Based on landing gear load calibration tests and flight test records, this invention converts the landing gear load measured in the flight's body coordinate system into a load in the ground coordinate system using a transformation matrix between the body coordinate system and the ground coordinate system. Simultaneously, considering the initial installation position of the aircraft position sensor, the measured position of the position sensor is converted into the position of the aircraft's center of gravity. The vertical load in the ground coordinate system and the vertical position at the aircraft's center of gravity are integrated to obtain the energy absorbed by the aircraft buffer system. Finally, the energy absorption efficiency of the buffer system is calculated based on the energy absorbed by the buffer system, the measured vertical load in the ground coordinate system, and the vertical position at the aircraft's center of gravity. This invention solves the problem of how to calculate the energy absorption efficiency of an aircraft buffer system based on flight test data, thereby determining the buffer performance of the aircraft buffer system under real-world operating conditions and providing more realistic data for buffer system performance evaluation.

[0073] This invention calculates the energy absorbed and energy absorption efficiency of the aircraft landing gear buffer system under full-size, real flight conditions based on data such as landing gear load, aircraft position coordinates, and aircraft attitude measured in actual flight.

[0074] The present application will be further described in detail below with reference to the accompanying drawings of the embodiments.

[0075] A method for calculating the energy absorption efficiency of an aircraft buffer system based on flight test data, the method comprising the following steps:

[0076] Step 1: Install multiple load-measuring strain gauges on the main force transmission channel of the landing gear structure, including strain gauges sensitive to vertical, yaw, and lateral loads of the landing gear; the main force transmission channel includes at least wheel axle, piston rod, outer cylinder, and struts, etc.

[0077] Specifically: strain gauges sensitive to vertical, yaw, and lateral loads of the landing gear are installed on the wheel axle; strain gauges sensitive to vertical and yaw loads of the landing gear are installed on the piston rod; strain gauges sensitive to yaw and lateral loads of the landing gear are installed on the outer cylinder; and strain gauges sensitive to yaw loads of the landing gear are installed on the strut.

[0078] Step 2: Load Calibration Test: After the landing gear is installed and fixed, under the fixed stroke of the buffer, apply unidirectional loading in the vertical, yaw, and lateral directions, as well as combined bidirectional and tridirectional loads. Record the load and structural strain data simultaneously during the test. Unidirectional loading in each direction is required, as are combined bidirectional and tridirectional loads. The fixed stroke of the buffer must include at least three sections, named s1, s2, and s3 in sequence. <s2<s3;

[0079] Step 3: Input the applied load and the measured structural strain data from the load strain gauge for each stroke into the load measurement model, and obtain the coefficients of the load measurement model through linear regression; the coefficients of the load measurement model for other strokes are obtained through linear interpolation.

[0080] The load testing model is:

[0081] F J =Kε ​​(1)

[0082] The linear regression solution formula for the load model coefficients is as follows:

[0083] K = F J (εε T ) -1 (2)

[0084] In equations (1) and (2): F J ε represents the applied load for the load calibration test; K is the load measurement model coefficient; ε is the structural strain measured by the load measurement strain gauge.

[0085] Other itineraries: Itineraries that are not any of s1, s2, or s3;

[0086] Formula for the difference of load model coefficients for other strokes:

[0087]

[0088] In equation (3): s is the buffer stroke; K s For the load model coefficient of the stroke s; These are the load model coefficients for strokes s1, s2, and s3, respectively.

[0089] Step 4: Before the flight test, install GPS or GNS to measure the three-dimensional position and three-dimensional velocity, and inertial navigation system to measure the three-dimensional attitude on the aircraft; in addition to the strain sensor installed in Step 1, a buffer displacement sensor should also be installed on the landing gear; at the same time, install test equipment on the aircraft to measure and record these parameters.

[0090] Step 5: Flight Test: Conduct a landing test flight with a high descent speed, requiring the pilot to maneuver the aircraft to land at the required descent speed; during the test, the test equipment simultaneously collects and records the flight data from Step 4;

[0091] Step 6: Flight Load Calculation: Input the structural strain data and buffer travel data from the measured flight data in Step 5 into the load model in Step 3 to obtain the measured flight load F. F ;

[0092] F F It is a column vector, formed by the measured heading load F. x Lateral load Fy and vertical load F z composition:

[0093]

[0094] The method further includes converting the triaxial load of the flight-measured load into a triaxial load in the ground coordinate system:

[0095] Step 7: Convert the measured load to the load in the ground coordinate system: Substitute the measured load and aircraft attitude into the conversion formula between the body coordinate system and the ground coordinate system.

[0096] The conversion formula between the body coordinate system and the ground coordinate system is as follows:

[0097]

[0098] P D It is a column vector, composed of three loads in the ground coordinate system, namely the heading load P. x Lateral load P y and vertical load P z composition:

[0099]

[0100] In equation (5), L T-D The transformation matrix from the aircraft body-axis coordinate system to the ground coordinate system is calculated using the following formula:

[0101]

[0102] In equation (6): θ is the aircraft yaw angle, θ is the aircraft pitch angle, and φ is the aircraft roll angle, which are measured by attitude sensors such as gyroscopes on the aircraft.

[0103] In actual flight testing, the aircraft's center of gravity is often occupied by the central fuel tank or other components, making it impossible to install sensors. Typically, a suitable location is found on the aircraft fuselage to install the position sensor. In this case, the sensor measures its own position, not the aircraft's center of gravity. Therefore, the method also includes converting the sensor position measured during flight testing into the aircraft's center of gravity position.

[0104] Step 8: Calculate the initial installation angle of the sensor: Obtain the installation position of the GNS position sensor in the body coordinate system as [x cgq_T y cgq_T z cgq_T ] T The initial installation angle of the sensor is calculated from the installation location.

[0105] The formula for calculating the initial installation angle is:

[0106]

[0107]

[0108] In the formula: θ0 is the initial installation yaw angle of the sensor, and θ0 is the initial installation pitch angle of the sensor; x cgq_T y cgq_T and z cgq_T These are the heading, lateral, and vertical mounting positions of the position sensor in the body coordinate system;

[0109] Step 9: Calculate the sensor coordinate transformation matrix: Substitute the initial installation angle of the sensor in Step 8 and the aircraft attitude angle in the measured flight data in Step 5 into the position coordinate transformation matrix to obtain the transformation matrix from the aircraft body axis coordinates to the ground coordinate system, taking into account the sensor installation position.

[0110] Formula for calculating the position coordinate transformation matrix:

[0111]

[0112] Step 10: Obtain the height of the aircraft's center of gravity relative to the ground: Substitute the position sensor data measured in Step 5 and the position coordinate transformation matrix in Step 9 into the center of gravity height calculation formula to obtain the center of gravity height.

[0113] Formula for calculating center of gravity height:

[0114]

[0115] In the formula: z cg x is the height of the aircraft's center of gravity. cgq_T y cgq_T and z cgq_T These are the heading, lateral, and vertical mounting positions of the position sensor in the body coordinate system, L. T_D_str (3,all) is the third row of the position coordinate transformation matrix in step 9;

[0116] The method further includes calculating the energy absorption efficiency of the buffer system based on flight test data:

[0117] Step 11: Calculate the energy absorbed by the buffer system during aircraft landing: Apply the vertical load data P from Step 7. z And the center of gravity height data z from step 10 cg Perform discrete integration to obtain the energy absorbed by the buffer system.

[0118] The curves showing the vertical load of the aircraft in the ground coordinate system as a function of the aircraft's center of gravity altitude are shown below. Figure 2 ,right Figure 2 Discrete integration of the curve in the figure represents the energy absorbed by the buffer system.

[0119] Discrete integral formula:

[0120]

[0121] In the formula: A c P is the energy absorbed by the buffer system. Z_i and P Z_i+1 Let z be the vertical load on the landing gear at sampling points i and i+1. cg_i and z cg_i+1 Let be the height of the aircraft's center of gravity at sampling point i.

[0122] Step 12: Calculate the maximum vertical load P measured during the aircraft landing process in Step 7. z_max z and the maximum vertical height of the center of gravity cg_max ;

[0123] Step 13: Energy absorption efficiency of the buffer system: Substitute the energy absorbed by the buffer system in step 11 and step 12 into the formula for calculating the efficiency of the buffer system.

[0124] Formula for calculating the efficiency of a buffer system:

[0125]

[0126] In the formula: η is the efficiency of the buffer system.

Claims

1. A method for calculating the energy absorption efficiency of an aircraft buffer system based on flight test data, characterized in that, Calculations for the energy absorption efficiency of aircraft buffer systems under real flight conditions include: The landing gear is subjected to load calibration tests to obtain test data, and the coefficients of the load measurement model are determined based on the test data; The measured data is input into the load model to obtain the measured external load. The measured external load is then projected onto the ground coordinate system according to the aircraft's attitude angle to obtain the measured load in the ground coordinate system. By inputting the measured sensor position, aircraft attitude, and initial sensor installation position into the coordinate transformation matrix, the aircraft's center of gravity height can be obtained. ; By integrating the measured load in the ground coordinate system and the position of the aircraft's center of gravity in the ground coordinate system, the energy absorbed by the aircraft's buffer system is obtained, and the energy absorption efficiency is calculated, specifically: Vertical load data and center of gravity height Perform discrete integration to obtain the energy absorbed by the buffer system; where the discrete integration formula is: In the formula: The energy absorbed by the buffer system and Sampling points and Vertical load on landing gear at any given moment. and Sampling points The height of the aircraft's center of gravity at any given moment; The maximum vertical load measured during aircraft landing is statistically analyzed. and the maximum vertical height of the center of gravity ; Calculate the efficiency of a buffer system using the buffer system efficiency calculation formula. : 。 2. The method according to claim 1, characterized in that, Load calibration tests were conducted on the landing gear to obtain test data. Based on the test data, the coefficients of the load measurement model were determined, including: Step 1: Install multiple load strain gauges on the main force transmission channel of the landing gear structure; Step 2: Load Calibration Test: After the landing gear is installed and fixed, apply unidirectional loading in the vertical, yaw, and lateral directions, as well as combined bidirectional and tridirectional loads, to the landing gear under the fixed stroke of the buffer. Record the load and structural strain data simultaneously during the test. Unidirectional loading in each direction is required, as are combined bidirectional and tridirectional loads. The fixed stroke of the buffer must include at least three sections, named sequentially as follows: , , , < < ; Step 3: Input the applied load and the measured structural strain data from the load strain gauge for each stroke into the load measurement model, and obtain the coefficients of the load measurement model through linear regression; the coefficients of the load measurement model for other strokes are obtained through linear interpolation. The load testing model is: （1） The linear regression solution formula for the load model coefficients is as follows: （2） In equations (1) and (2): The applied load for the load calibration test; K These are the coefficients of the load measurement model; The structural strain was measured using a load strain gauge. Other itineraries: The itinerary is not... , , Any trip; Formula for the difference of load model coefficients for other strokes: （3） In formula (3): s For the buffer travel; For the itinerary s The load model coefficients; , , respectively itinerary , , The load model coefficients.

3. The method according to claim 2, characterized in that, The measured data is input into the load model to obtain the measured external load. Based on the aircraft's attitude angles, the measured external load is projected onto the ground coordinate system to obtain the measured load in the ground coordinate system, including: Step 4: Before the flight test, install GPS or GNSS to measure the three-dimensional position and three-dimensional velocity, and inertial navigation to measure the three-dimensional attitude on the aircraft; in addition to the strain gauges installed in Step 1, buffer displacement sensors should also be installed on the landing gear; at the same time, test equipment for measuring and recording these parameters should be installed on the aircraft. Step 5: Flight Test: Conduct a landing test flight with a high descent speed, requiring the pilot to maneuver the aircraft to land at the required descent speed; during the test, the test equipment collects and records flight data; Step 6: Flight Load Calculation: Input the structural strain data and buffer travel data from the measured flight data in Step 5 into the load model in Step 3 to obtain the measured flight load. ; （4） Step 7: Convert the measured load to a ground coordinate system: Substitute the measured load and aircraft attitude into the conversion formula between the body coordinate system and the ground coordinate system: The conversion formula between the body coordinate system and the ground coordinate system is as follows: （5） Heading load Lateral loads Vertical load : In equation (5), The transformation matrix from the aircraft body-axis coordinate system to the ground coordinate system is calculated using the following formula: （6） In formula (6): For aircraft yaw angle, For aircraft pitch angle, The roll angle of the aircraft.

4. The method according to claim 3, characterized in that, By inputting the measured sensor position, aircraft attitude, and initial sensor installation position into the coordinate transformation matrix, the position of the aircraft's center of gravity in ground coordinates is obtained, including: Step 8: Calculate the initial installation angle of the sensor: Obtain the installation position of the GNSS position sensor in the body coordinate system. The initial installation angle of the sensor is calculated from the installation location; The formula for calculating the initial installation angle is: In the formula: For the initial installation of the sensor, yaw angle, The initial installation pitch angle for the sensor; , and These are the heading, lateral, and vertical mounting positions of the position sensor in the body coordinate system; Step 9: Calculate the sensor coordinate transformation matrix: Substitute the initial installation angle of the sensor in Step 8 and the aircraft attitude angle in the measured flight data into the position coordinate transformation matrix. The position coordinate transformation matrix is ​​the transformation matrix from the aircraft body axis coordinates to the ground coordinate system, which takes into account the sensor installation position. Formula for calculating the position coordinate transformation matrix: Step 10: Obtain the height of the aircraft's center of gravity relative to the ground: Substitute the position sensor data from the measured flight data and the position coordinate transformation matrix from Step 9 into the center of gravity height calculation formula to obtain the center of gravity height. Formula for calculating center of gravity height: In the formula: The height of the aircraft's center of gravity. , and These refer to the heading, lateral, and vertical mounting positions of the position sensors in the airframe coordinate system. This is the third row of the position coordinate transformation matrix.

5. The method according to claim 4, characterized in that, In step 1, the main force transmission channel includes at least the wheel axle, piston rod, outer cylinder, and support rod.

6. The method according to claim 5, characterized in that, In step 1, strain gauges sensitive to vertical, yaw, and lateral loads of the landing gear are installed on the wheel axle; strain gauges sensitive to vertical and yaw loads of the landing gear are installed on the piston rod; strain gauges sensitive to yaw and lateral loads of the landing gear are installed on the outer cylinder; and strain gauges sensitive to yaw loads of the landing gear are installed on the strut.

7. The method according to claim 6, characterized in that, During the flight test, the sampling frequency of the test parameters was no less than 128 Hz.

8. The method according to claim 7, characterized in that, In step 4, sensors for measuring three-dimensional position, three-dimensional velocity, and three-dimensional attitude are installed on the aircraft.

9. The method according to claim 8, characterized in that, In step 4, the measured load in the ground coordinate system and the position of the aircraft's center of gravity in the ground coordinate system are integrated to obtain the energy absorbed by the aircraft's buffer system.

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