Decoupling method and device for strain gauge measurement data of landing load of undercarriage

Abstract

The invention provides a decoupling method and device for strain gauge measurement data of landing load of an undercarriage. The method comprises the steps that two sets of strain gauges are arranged at the position of an axle of the undercarriage; wherein one group of strain gauges are uniformly distributed on the circumference of the wheel shaft, and each of the two opposite strain gauges is provided with two strain gauges which are inclined by 45 degrees to form a strain rosette structure; the other group of strain gauges are uniformly distributed on the circumference of the wheel shaft; the distance between the two groups of strain gauges in the length direction of the axle is a preset value L; determining the ground vertical load of the undercarriage based on the strain value of the strain gauge on the vertical surface; determining a first ground course load Fx1 of the undercarriage based on the strain value of the strain gauge inclined by 45 degrees; determining a second ground course load Fx2 of the undercarriage based on the strain value of the strain gauge on the horizontal plane; when the absolute value of the difference value between the Fx1 and the Fx2 is smaller than or equal to a first threshold value, the target ground course load of the undercarriage is determined; determining a first ground lateral load Fy1 of the undercarriage based on the strain values of the first group of strain gauges; determining a second ground lateral load Fy2 of the undercarriage based on the strain value of the strain gauge on the vertical surface; when the absolute value of the difference value between the Fy1 and the Fy2 is smaller than or equal to a second threshold value, the target ground lateral load of the undercarriage is determined; according to the method, any target load can be solved independently and is not interfered by other loads. The solving result of the landing load can be subjected to cross validation according to different strain combinations, and the validation range covers all load working conditions.

Description

Technical Field

[0001] The present application belongs to the technical field of load measurement, and in particular, relates to a method and device for decoupling strain gauge measurement data of landing gear landing load. Background Art

[0002] The landing gear is a key structural component used to bear the landing load during the take-off and landing process of the helicopter. During the operation and maintenance stage, the landing gear lacks the means to measure the actual landing load. The health status of the landing gear depends on regular inspections for maintenance, and comprehensive disassembly is required, resulting in long maintenance cycles, high costs, and low efficiency. In addition, the landing load spectrum, as an important input for landing gear fatigue life determination, usually uses drop test data or theoretical analysis and calculations as the main reference, which cannot truly reflect the actual state of the landing gear. Therefore, there is an urgent need for a load measurement decoupling method to support technical research on landing gear fatigue damage, health monitoring, and life assessment.

[0003] The landing gear landing load is affected by factors such as the helicopter landing attitude and landing speed. Except for the vertical load, the distribution direction and magnitude of the load in other directions cannot be predicted. Traditional strain gauge measurement and grating measurement obtain the strain results at the sensor layout point. The strain results are generated by the superposition of complex loads, and it is difficult to decouple the landing load and analyze the distribution state of the landing load. Summary of the invention

[0004] In order to solve the technical problem in the related art that the strain results are generated by the superposition of complex loads, and it is difficult to decouple the landing load and analyze the distribution state of the landing load, the present invention proposes a decoupling method and device for the strain gauge measurement data of the landing load of the landing gear, and establishes a ground three-way landing load decoupling calculation model, which can independently solve any target load without being interfered by other loads. In addition, the solution of the landing load can be cross-validated according to different strain combinations, and the verification range covers all load conditions and can be automatically solved. The technical solution is as follows:

[0005] In a first aspect, a method for decoupling strain gauge measurement data of landing gear landing load is provided, the method comprising:

[0006] Step 1, two groups of strain gauges are arranged at the landing gear wheel axle; one group of strain gauges is evenly distributed on the circumference of the wheel axle, and two opposite strain gauges are each provided with two strain gauges inclined at 45 degrees to form a strain rosette structure; the other group of strain gauges is evenly distributed on the circumference of the wheel axle; and the distance between the two groups of strain gauges along the length direction of the wheel axle is a preset value L; each group of strain gauges includes at least 4 strain gauges;

[0007] Step 2, obtaining the strain value of each strain gauge;

[0008] Step 3: Determine the ground vertical load of the landing gear based on the strain value of the strain gauge on the vertical surface;

[0009] Step 4: Determine the first ground heading load F of the landing gear based on the strain value of the strain gauge inclined at 45° x1 Based on the strain value of the strain gauge on the horizontal plane, determine the second ground heading load F of the landing gear x2 When F x1 and F x2 When the absolute value of the difference is less than or equal to the first threshold, F x1 and F x2 The mean of is taken as the target ground heading load of the landing gear;

[0010] Step 5: Determine the first ground lateral load F of the landing gear based on the strain values ​​of the first set of strain gauges. y1 Based on the strain value of the strain gauge on the vertical surface, determine the second ground lateral load F of the landing gear y2 When F y1 and F y2 When the absolute value of the difference between y1 and F y2 The mean of is taken as the target ground side load of the landing gear.

[0011] Among them, each group of strain gauges includes 4 strain gauges, the first group of strain gauges are strain gauge 1, strain gauge 2, strain gauge 3, strain gauge 4, strain gauge 3 is provided with two strain gauges inclined at 45°, namely strain gauge 9 and strain gauge 10, strain gauge 4 is provided with two strain gauges inclined at 45°, namely strain gauge 11 and strain gauge 12; the second group of strain gauges are strain gauge 5, strain gauge 6, strain gauge 7, strain gauge 8.

[0012] Optionally, in step 3, the process of determining the ground vertical load of the landing gear based on the strain value of the strain gauge on the vertical surface is:

[0013] Calculate the ground vertical load of the landing gear according to the vertical load calculation formula Where E is the elastic modulus of the axle material, W is the bending section coefficient, ε i is the strain value of strain gauge i, i is equal to 1, 2, 5, 6.

[0014] Optionally,

[0015] The first ground heading load F x1 The calculation formula is Where E is the elastic modulus of the axle material, Wt is the torsional section coefficient, d is the wheel radius, ε i is the strain value of strain gauge i, i is equal to 9, 10, 11, 12;

[0016] Optionally, the second ground heading load F x2 The calculation formula is Where E is the elastic modulus of the axle material, W is the bending section coefficient, ε i is the strain value of strain gauge i, i is equal to 3, 4, 7, 8.

[0017] Optionally,

[0018] First ground lateral load F y1 The calculation formula is Where E is the elastic modulus of the axle material, A is the cross-sectional area of ​​the axle, and ε i is the strain value of strain gauge i, i is equal to 1, 2, 3, 4;

[0019] Second ground lateral load F y2 The calculation formula is Where E is the elastic modulus of the axle material, A is the cross-sectional area of ​​the axle, and ε i is the strain value of strain gauge i, i is equal to 1, 2, 5, 6.

[0020] Optionally,

[0021] The wheel torque is calculated based on the target ground heading load and the wheel radius d. According to the actual rotation torque of the wheel, the braking torque of the wheel brake device is accurately designed, providing important input for the structural design of the brake device and the calculation of the aircraft taxiing performance.

[0022] In a second aspect, a decoupling device for strain gauge measurement data of landing gear landing load is provided, comprising:

[0023] An arrangement module is used to arrange two groups of strain gauges at the landing gear wheel axle position; one group of strain gauges is evenly distributed on the circumference of the wheel axle, and two opposite strain gauges are each provided with two strain gauges inclined at 45 degrees to form a strain rosette structure; the other group of strain gauges is evenly distributed on the circumference of the wheel axle; and the distance between the two groups of strain gauges along the length direction of the wheel axle is a preset value L; each group of strain gauges includes at least 4 strain gauges;

[0024] An acquisition module, used for acquiring the strain value of each strain gauge;

[0025] Identify modules for:

[0026] Determine the ground vertical load of the landing gear based on the strain value of the strain gauge on the vertical surface;

[0027] Based on the strain value of the strain gauge inclined at 45°, determine the first ground heading load F of the landing gear. x1 Based on the strain value of the strain gauge on the horizontal plane, determine the second ground heading load F of the landing gear x2 When F x1and F x2 When the absolute value of the difference is less than or equal to the first threshold, F x1 and F x2 The mean of is taken as the target ground heading load of the landing gear;

[0028] Based on the strain values ​​of the first set of strain gauges, determine the first ground lateral load F of the landing gear. y1 Based on the strain value of the strain gauge on the vertical surface, determine the second ground lateral load F of the landing gear y2 When F y1 and F y2 When the absolute value of the difference between y1 and F y2 The mean of is taken as the target ground side load of the landing gear.

[0029] The landing gear landing load decoupling calculation in this application is directly related to the use and maintenance of key components such as buffers, sway reduction devices, and brake devices. Compared with theoretical calculations, drop shock test detection and other means, it can more truly reflect the combination and distribution of loads during landing, and is of great significance to the drawing of landing load spectra, landing gear structure health monitoring and failure mode analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the layout of strain gauges at the wheel axle;

[0031] Figure 2 This is a schematic diagram of strain gauge layout scheme 2;

[0032] Figure 3 Schematic diagram of strain gauge layout plan three. DETAILED DESCRIPTION

[0033] The present application is further described in detail below through specific implementation methods and drawings.

[0034] 1) Taking the strut landing gear as an example, the wheel axle is involved in the transmission of all ground loads, and the layout of the strain gauges is designed Figure 1 As shown in the figure, the pasting direction of strain gauges 1-8 is parallel to the axis of the wheel axle, strain gauges 1 / 2 / 5 / 6 are on the XOZ coordinate axis plane, strain gauges 3 / 4 / 7 / 8 are on the XOY coordinate axis plane, strain gauges 9 / 10 / 11 / 12 are inclined at an angle of 45°, and strain gauges 9 / 3 / 10 and strain gauges 11 / 4 / 12 form strain rosettes respectively.

[0035] The relationship between the measurement results of strain gauges 1-12 and the strains corresponding to the bending moment, torsion, shear force, tension and compression generated by the three-axis load on the ground is analyzed as follows:

[0036]

[0037] Based on the strain results collected by the strain gauge 9, the bending moment generated by the axial load Fx is expressed as tensile stress, so the load direction is positive; the torque generated by the axial load Fx is positive according to the layout direction of the strain gauge 9; the extrusion stress generated by the lateral load Fy is negative; the shear force generated by the vertical load Fz is negative. The directions corresponding to the above loads are recorded as [+, +, -, -], corresponding to the load directions of Fx, Fx, Fy, and Fz in formula (1).

[0038] The nature and magnitude of the loads borne by strain gauges 10, 11, and 12 are the same as those of strain gauge 9. Due to the symmetry of the layout positions, only the load directions are different. According to the load direction of strain gauge 9, the load direction of strain gauge 10 is [+, -, -, +], the load direction of strain gauge 11 is [-, -, -, -], and the load direction of strain gauge 12 is [-, +, -, +].

[0039]

[0040] Taking the strain results collected by strain gauge 1 as the reference, the bending moment generated by the lateral load Fy is expressed as tensile stress, so the load direction is positive; the bending moment generated by the lateral load Fy is expressed as extrusion stress, so the load direction is negative; the bending moment generated by the vertical load Fz is expressed as extrusion stress, so the load direction is negative. The directions corresponding to the above loads are recorded as [+, -, -], corresponding to the load directions of Fy, Fy, and Fz in formula (2). The nature and magnitude of the load borne by strain gauge 2 are the same as those of strain gauge 1, and the load direction is [-, -, +].

[0041]

[0042] The nature of the load borne by strain gauges 5 and 6 is the same as that of strain gauge 1, but the load magnitude and direction are different, which are expressed by formulas (3) and (4).

[0043]

[0044] Taking the load direction shown by strain gauge 3 as the reference, the bending moment generated by the axial load Fx is expressed as tensile stress, so the load direction is positive; the lateral load Fy generates extrusion stress, so the load direction is negative. The directions corresponding to the above loads are recorded as [+,-], corresponding to the Fx and Fy load directions in formula (5). The nature and magnitude of the load borne by strain gauge 4 are the same as those of strain gauge 3, and the load direction is [-,-].

[0045]

[0046] The load properties of strain gauges 7 and 8 are the same as those of strain gauge 3, but the load magnitude and direction are different, which are expressed by formulas (6) and (7).

[0047] In the above formula, W represents the bending section coefficient, Wt represents the torsional section coefficient, r represents the tire radius, A represents the cross-sectional area of ​​the wheel axle, E represents the elastic modulus, d1 and d2 represent the force arms at the relevant load and strain gauge layout position, and L=|d2-d1| represents the cross-sectional distance between the two sets of strain gauges.

[0048] 3) The vertical load Fz is decoupled and calculated using the measurement results of strain gauges 1 / 2 / 5 / 6. The strain gauges can be full-bridge overlapped. For specific methods, please refer to the strain gauge overlap technology.

[0049]

[0050] 4) According to formulas (1)-(7), there are two methods to calculate the heading load Fx. The first method uses the measurement data of strain gauges 9 / 10 / 11 / 12, and the strain gauges can be full-bridge overlapped. For specific methods, please refer to the strain gauge overlap technology.

[0051]

[0052] The second method uses strain gauges 3 / 4 / 7 / 8. The strain gauges can be full-bridge overlapped. The specific method can refer to the strain gauge overlap technology. L represents the cross-sectional distance between the two sets of strain gauges, which is a constant value.

[0053]

[0054] The difference of heading load calculated by two methods |F x1 -F x2 | is less than the set threshold, the average of the two values ​​is taken as the calculation result of the heading load Fx.

[0055] 5) The lateral load Fy can be calculated by decoupling using the measurement results of strain gauges 1 / 2 / 3 / 4 or 1 / 2 / 5 / 6. If the difference between the lateral load Fy calculated by the two methods is less than the set threshold, the average value is taken as the calculation result of the lateral load Fy. The set threshold is 5% of the vertical load.

[0056]

[0057] Strain gauges 1 / 2 / 3 / 4 or 1 / 2 / 5 / 6 can be connected in series with a half-bridge. For specific methods, please refer to the strain gauge connection technology.

[0058] The invention has small calculation error and concise calculation process, and can solve all load conditions of the landing gear to obtain the distribution direction and magnitude of the ground load. Moreover, the calculation method of the lateral load and the heading load is not unique, and the calculation results can be mutually verified.

[0059] In the present invention, the strain gauges arranged in the above manner can be used to calculate the wheel torque in addition to the load. After the load is obtained, the wheel axle torque can be calculated in combination with the wheel radius d. For example, based on the target ground heading load and the wheel radius d, the wheel torque can be calculated, and the braking torque of the wheel brake device can be accurately designed according to the actual rotation torque of the wheel, providing important input for the structural design of the brake device and the calculation of the aircraft taxiing performance.

[0060] The strain gauge layout scheme proposed in the present invention can be simplified according to the actual application and the space limitation of the landing gear position. The first scheme uses 8 strain gauges 1-8, see Figure 2 The second scheme uses 10 strain gauges 1-6, 9-12, see Figure 3 , each scheme can independently complete the calculation and solution of the three-dimensional ground load.

[0061] Select a landing gear axle with an inner diameter of 30mm and an outer diameter of 40mm. The material is structural steel and the tire radius r = 315mm. Calculate the bending section coefficient W = 34361mm^3, the torsion section coefficient Wt = 68722mm^3, the axle cross-sectional area A = 2198mm^2, the elastic modulus E = 2e11Pa, and the spacing between the two cross-section strain gauges L = 40mm. Figure 1 The strain gauges are arranged in the manner shown.

[0062] Example 1: Bidirectional ground loads are applied, namely, axial load Fx=0N, vertical load Fz=10000N, and lateral load Fy=5000N, and the simulation data of the wheel axle strain gauge is shown in Table 1.

[0063] Table 1 Bidirectional load strain simulation data

[0064] Strain gauge 1 8.40e-5 Strain gauge 7 -1.22e-5 Strain gauge 2 -1.09e-4 Strain gauge 8 -1.28e-5 Strain gauge 3 -9.37e-6 Strain gauge 9 -5.9e-5 Strain gauge 4 -1.17e-5 Strain gauge 10 5.32e-5 Strain gauge 5 2.78e-5 Strain gauge 11 -6.34e-5 Strain gauge 6 -5.00e-5 Strain gauge 12 5.20e-5

[0065] 1. Substitute the measurement data of strain gauges 1 / 2 / 5 / 6 into formula (10) and obtain the vertical load Fz=9896N.

[0066] 2. Substitute the measured data of strain gauges 9 / 10 / 11 / 12 into formula (8) to obtain the heading load F x1 =34N;

[0067] 3. Substitute the measured data of strain gauges 3 / 4 / 7 / 8 into formula (9) to obtain the heading load F x2 =31N;

[0068] 4. Set threshold = Fz*0.05 = 495N, |F x2 -F x1 |=3N<495N, get the heading load F x =(F x2 +F x1 ) / 2=32.5N;

[0069] 5. Substitute the measured data of strain gauges 1 / 2 / 3 / 4 into formula (11) to obtain the lateral load F y1 =-5055N, the negative sign represents the lateral load F borne by the wheel axle y It manifests itself as compressive stress.

[0070] 6. Substitute the measured data of strain gauges 1 / 2 / 5 / 6 into formula (12) to obtain the lateral load F y2 =-5187N, the negative sign represents the lateral load F borne by the wheel axle y It manifests itself as compressive stress.

[0071] 7. Set threshold = Fz*0.025 = 248N, calculate |F y2 -F y1 |=132N<threshold value, and the lateral load Fy=(F y2 +F y1 ) / 2=-5121N.

[0072] 8. Calculation error of vertical load Fz = (10239-10000) / 10000 = 2.39%,

[0073] 9. Calculation error of lateral load Fy = (5187-5055) / 5000 = 3.74%.

[0074] It can be seen that the present invention has a small error and a simple calculation process. It can solve all load conditions of the landing gear and obtain the distribution direction and size of the ground load. The calculation methods of the lateral load and the heading load are not unique, and the calculation results can be mutually verified.

[0075] Example 2: Apply three-axis loads Fx=5000N, Fy=5000N, Fz=10000N, and obtain the strain data of each position of the wheel axle as shown in Table 2.

[0076] Table 2 Three-axis load-strain simulation data

[0077] Strain gauge 1 8.77e-5 Strain gauge 7 1.02e-4 Strain gauge 2 -1.09e-4 Strain gauge 8 -1.34e-4 Strain gauge 3 7.73e-5 Strain gauge 9 1.04e-4 Strain gauge 4 -1.02e-4 Strain gauge 10 -5.24e-5 Strain gauge 5 2.45e-5 Strain gauge 11 -1.81e-4 Strain gauge 6 -5.02e-5 Strain gauge 12 1.05e-4

[0078] 1. Substitute the measured data of strain gauges 1 / 2 / 5 / 6 into formula (8) to obtain the vertical load Fz=10480N;

[0079] 2. Substitute the measured data of strain gauges 9 / 10 / 11 / 12 into formula (9) to obtain the heading load F x1 =4825N;

[0080] 3. Substitute the measured data of strain gauges 3 / 4 / 7 / 8 into formula (10) to obtain the heading load F x2 =4870N;

[0081] 4. Set threshold = Fz*0.05 = 524N, | F x2 -F x1 |=45N<524N, and the heading load Fx=(F x2 +F x1 ) / 2=4847.5N;

[0082] 5. Substitute the measured data of strain gauges 1 / 2 / 3 / 4 into formula (11) to obtain the lateral load F y1 =-5055N, the lateral load Fy borne by the negative wheel axle is manifested as extrusion stress;

[0083] 6. Substitute the measured data of strain gauges 1 / 2 / 5 / 6 into formula (12) to obtain the lateral load F y2 =-5165N, the lateral load Fy borne by the negative wheel axle is manifested as extrusion stress;

[0084] 7. Set threshold = Fz*0.025 = 262N, calculate |F y2 -F y1 |=110N<threshold value, and the lateral load Fy=(F y2 +F y1 ) / 2=-5110N.

[0085] 8. Calculation error of vertical load Fz = (10480-10000) / 10000 = 4.8%,

[0086] 9. Calculation error of lateral load Fy = (5110-5000) / 5000 = 2.2%,

[0087] 10. Calculation error of heading load Fx = (4847.5-5000) / 5000 = 3.05%

[0088] In summary, the present invention can decouple and calculate any form of ground load based on the strain measurement results of the landing gear axle to obtain the value and direction of the landing load. The present invention proposes two different decoupling methods for the lateral load and axial load in the landing load, and the solution results can be cross-validated according to different strain combinations. The present invention can independently solve the landing load in any direction without being interfered by other loads, and the calculation results are accurate and reliable. The present invention sorts out the strain distribution characteristics at the landing gear axle in detail, and the proposed calculation model covers all load conditions of the landing gear, and the solution process is intuitive and concise.

[0089] The above only expresses the implementation methods of the present application, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. In addition, the parts that are not detailed in this application are all conventional technologies.

Claims

1. A method for decoupling strain gauge measurement data of landing gear landing load, characterized in that: The method comprises: Step 1, two groups of strain gauges are arranged at the landing gear wheel axle; one group of strain gauges is evenly distributed on the circumference of the wheel axle, and two opposite strain gauges are each provided with two strain gauges inclined at 45 degrees to form a strain rosette structure; the other group of strain gauges is evenly distributed on the circumference of the wheel axle; and the distance between the two groups of strain gauges along the length direction of the wheel axle is a preset value L; each group of strain gauges includes at least 4 strain gauges; Step 2, obtaining the strain value of each strain gauge; Step 3: Determine the ground vertical load of the landing gear based on the strain value of the strain gauge on the vertical surface; Step 4: Determine the first ground heading load F of the landing gear based on the strain value of the strain gauge inclined at 45° x1 Based on the strain value of the strain gauge on the horizontal plane, determine the second ground heading load F of the landing gear x2 When F x1 and F x2 When the absolute value of the difference is less than or equal to the first threshold, F x1 and F x2 The mean of is taken as the target ground heading load of the landing gear; Step 5: Determine the first ground lateral load F of the landing gear based on the strain values ​​of the first set of strain gauges. y1 Based on the strain value of the strain gauge on the vertical surface, determine the second ground lateral load F of the landing gear y2 When F y1 and F y2 When the absolute value of the difference between y1 and F y2 The mean of is taken as the target ground side load of the landing gear.

2. The method according to claim 1, characterized in that Each group of strain gauges includes 4 strain gauges. The first group of strain gauges are strain gauge 1, strain gauge 2, strain gauge 3, and strain gauge 4. Strain gauge 3 is provided with two strain gauges inclined at 45°, namely strain gauge 9 and strain gauge 10. Strain gauge 4 is provided with two strain gauges inclined at 45°, namely strain gauge 11 and strain gauge 12. The second group of strain gauges are strain gauge 5, strain gauge 6, strain gauge 7, and strain gauge 8.

3. The method according to claim 2, characterized in that In step 3, the process of determining the ground vertical load of the landing gear based on the strain value of the strain gauge on the vertical surface is: Calculate the ground vertical load of the landing gear according to the vertical load calculation formula Where E is the elastic modulus of the axle material, W is the bending section coefficient, ε i is the strain value of strain gauge i, i is equal to 1, 2, 5, 6.

4. The method according to claim 2, characterized in that: The first ground heading load F x1 The calculation formula is Where E is the elastic modulus of the axle material, Wt is the torsional section coefficient, d is the wheel radius, ε i is the strain value of strain gauge i, i is equal to 9, 10, 11, 12.

5. The method according to claim 2, characterized in that: The second ground heading load F x2 The calculation formula is Where E is the elastic modulus of the axle material, W is the bending section coefficient, ε i is the strain value of strain gauge i, i is equal to 3, 4, 7, 8.

6. The method according to claim 2, characterized in that First ground lateral load F y1 The calculation formula is Where E is the elastic modulus of the axle material, A is the cross-sectional area of ​​the axle, and ε i is the strain value of strain gauge i, i is equal to 1, 2, 3, 4; Second ground lateral load F y2 The calculation formula is Where E is the elastic modulus of the axle material, A is the cross-sectional area of ​​the axle, and ε i is the strain value of strain gauge i, i is equal to 1, 2, 5, 6.

7. The method according to claim 1, characterized in that The wheel torque is calculated based on the target ground heading load and the wheel radius d.

8. A decoupling device for strain gauge measurement data of landing gear landing load, characterized in that: include: An arrangement module is used to arrange two groups of strain gauges at the landing gear wheel axle position; one group of strain gauges is evenly distributed on the circumference of the wheel axle, and two opposite strain gauges are each provided with two strain gauges inclined at 45 degrees to form a strain rosette structure; the other group of strain gauges is evenly distributed on the circumference of the wheel axle; and the distance between the two groups of strain gauges along the length direction of the wheel axle is a preset value L; each group of strain gauges includes at least 4 strain gauges; An acquisition module, used for acquiring the strain value of each strain gauge; Identify modules for: Determine the ground vertical load of the landing gear based on the strain value of the strain gauge on the vertical surface; Based on the strain value of the strain gauge inclined at 45°, determine the first ground heading load F of the landing gear. x1 Based on the strain value of the strain gauge on the horizontal plane, determine the second ground heading load F of the landing gear x2 When F x1 and F x2 When the absolute value of the difference is less than or equal to the first threshold, F x1 and F x2 The mean of is taken as the target ground heading load of the landing gear; Based on the strain values ​​of the first set of strain gauges, determine the first ground lateral load F of the landing gear. y1 Based on the strain value of the strain gauge on the vertical surface, determine the second ground lateral load F of the landing gear y2 When F y1 and F y2 When the absolute value of the difference between y1 and F y2 The mean of is taken as the target ground side load of the landing gear.

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