Telescopic arm sliding block gap optimization method of unmanned aerial vehicle vertical recovery device

Abstract

The invention provides a telescopic arm sliding block gap optimization method for a vertical recovery device of an unmanned aerial vehicle, and the method comprises the steps: giving a multi-field coupling interval optimization theory of engineering machinery gap design from the six aspects of thermodynamics, dynamics, tribology, fatigue life, comprehensive cost and manufacturing process, and calculating an optimal theoretical value of a sliding block gap; and the gap between the limiting slide block of the outer telescopic arm and the inner telescopic arm is adjusted, so that the gap is controlled to be an optimal theoretical value. By means of the tiny gap design, the movement range of the telescopic arm during collision of the unmanned aerial vehicle is limited, the torsion amplitude of lateral force on the telescopic arm is reduced, and therefore the risk that the steel cable falls off is reduced, and the performance and reliability of the unmanned aerial vehicle recovery device are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of vertical recovery technology for unmanned aerial vehicles (UAVs), and more specifically to a method for optimizing the gap between the telescopic arm sliders of a UAV vertical recovery device. Background Technology

[0002] Vertical recovery is a common method for recovering drones, suitable for specific scenarios, and has the advantages of low cost, few restrictions, and high recovery efficiency. Existing vertical recovery devices include a telescopic arm, an upper crossbar, and a lower crossbar. The upper and lower crossbars are connected by an arresting cable, forming a trapezoidal spatial structure. When the drone is recovered, the leading edge of the wing impacts the arresting cable, and the small hook at the wingtip locks with the arresting cable, thus fixing the drone to the arresting cable and completing the recovery.

[0003] The drone vertical recovery device is equipped with a multi-section telescopic arm to adjust the recovery height. When the drone collides with the arresting cable, the upper crossbar will sway significantly laterally, and the force will be applied as follows: Figure 2 As shown, these swings are transmitted to the telescopic arm, causing it to rotate. This can lead to the arresting cable detaching from the pulley of the telescopic arm, or cause the pulley to be damaged due to excessive lateral force. Consequently, the small hook on the tip of the drone's wing may detach during the swinging process, resulting in recovery failure and damage to the drone. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a method for optimizing the gap of the telescopic arm slider of a drone vertical recovery device. By optimizing the gap of the telescopic arm limit slider, the lateral swing amplitude of the telescopic arm is reduced, thereby solving the problem of the arresting cable easily falling off and ensuring the safety of drone recovery.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for optimizing the slider clearance of a telescopic arm in a vertical recovery device for unmanned aerial vehicles (UAVs) includes the following steps:

[0007] S1. Setting up limiting sliders: The UAV vertical recovery device includes n telescopic arms, n≥2. Two adjacent telescopic arms are divided into an outer telescopic arm and an inner telescopic arm. The inner telescopic arm is slidably set inside the outer telescopic arm. A limiting slider is set between the inner side of the outer telescopic arm head and the inner telescopic arm. Each limiting slider is equipped with a position adjustment device to adjust the slider gap.

[0008] S2. Calculate the theoretical range of the slider clearance: Through thermodynamic boundary calculations and tribological boundary calculations, obtain the theoretical minimum value δ of the slider clearance. min The theoretical maximum value δ of the slider gap was obtained through dynamic boundary calculations. max The theoretical range of the slider gap [δ] is obtained. min， δmax ];

[0009] S3. Calculate the optimal theoretical value of slider clearance: Construct a comprehensive cost-effectiveness evaluation model, calculate the comprehensive cost-effectiveness index of different slider clearances within the theoretical range, and determine the slider clearance with the largest comprehensive cost-effectiveness index as the optimal theoretical value;

[0010] S4. Adjust the slider gap: Align the outer telescopic arm and the inner telescopic arm, and adjust the slider gap to the optimal theoretical value of the slider gap using the position adjustment device.

[0011] As a preferred embodiment, in S1, the limiting slider is an L-shaped slider, with a total of four, which are symmetrically arranged at the four corners of the inner side of the arm head of the outer telescopic arm.

[0012] The position adjustment device includes bolt group one and bolt group two. Bolt group one adjusts the slider gap between the upper and lower limit sliders, and bolt group two adjusts the slider gap between the left and right limit sliders.

[0013] As a preferred option, the thermodynamic boundary calculation method in S2 is as follows:

[0014] Calculate the total thermal deformation ;

[0015] (1)

[0016] Where L is the length of the inner telescopic arm extending beyond the outer telescopic arm, in mm; α is the coefficient of linear expansion of the material, in 1 / ℃; ΔT is the temperature difference of the working environment, in ℃; This represents the total thermal deformation, expressed in mm.

[0017] Calculate the theoretical minimum value δ1 of the slider gap that meets the thermodynamic requirements;

[0018] δ1 (2)

[0019] in, This is for the safety factor.

[0020] As a preferred embodiment, in S2, the tribological boundary calculation method is specifically as follows:

[0021] Calculate the threshold of lubricating oil film thickness that meets the engineering life requirements, and calculate the theoretical minimum value δ2 of slider clearance that meets this threshold.

[0022] The formula for calculating the thickness of the lubricating oil film for different slider clearances is as follows:

[0023] (3)

[0024] in, The thickness of the lubricating oil film is in μm. The sliding speed is in m / s; 38.7 is the dynamic viscosity of the grease, Pa·s; 38.7 is an empirically fitted value.

[0025] Calculate the equipment wear rate for different slider clearances to determine whether the equipment wear rate meets the standard.

[0026] (4)

[0027] Where k is the wear coefficient; P is the contact pressure (MPa); L is the sliding distance (m); and H is the material hardness (MPa). This is the oil film thickness correction factor;

[0028] The theoretical minimum value δ2 of the slider clearance was obtained, which ensured that the equipment wear rate met the standard and the lubricating oil film thickness requirement.

[0029] By combining thermodynamic boundary calculations, the theoretical minimum value of the slider gap is obtained. .

[0030] As a preferred embodiment, in S2, the specific method for calculating the dynamic boundary is as follows:

[0031] The theoretical maximum value δ of the slider clearance is calculated based on the corresponding dynamic model. max And the torsional deformation was verified.

[0032] δ max (5)

[0033] Among them, t max The maximum allowable response time is expressed in seconds (s); a is the slider contact acceleration, expressed in m / s².

[0034] The formula for calculating torsional deformation is as follows:

[0035] (6)

[0036] in, The torsion angle is T, the maximum working torque is N·m, and the telescopic boom length is m. The shear modulus of the material is expressed in Pa. The polar moment of inertia, in meters. 4 .

[0037] As a preferred option, in S3, the specific method for calculating the comprehensive cost-effectiveness index is as follows:

[0038] S3.1. Within the theoretical range, select different slider gaps at certain intervals as test data, calculate the energy absorption rate E, response time R, and fatigue life F corresponding to each slider gap, and perform normalization processing to obtain the normalized score S of the energy absorption rate.E Normalized score of response time S R Normalized score S of fatigue life F ;

[0039] The normalized formula for energy absorption rate is:

[0040] (7)

[0041] Among them, E min E represents the minimum energy absorption rate calculated from the test data. max This represents the maximum energy absorption rate calculated from the test data.

[0042] The normalization formula for response time is:

[0043] (8)

[0044] Among them, R min R is the minimum response time calculated from the test data. max This is the maximum response time calculated from the test data;

[0045] The normalized formula for fatigue life is:

[0046] (9)

[0047] Among them, F min F represents the minimum fatigue life calculated from the test data. max This represents the maximum fatigue life calculated from the test data.

[0048] S3.2 Calculate the performance score P and cost index C of different slider gaps within the theoretical range, and obtain the comprehensive cost-effectiveness index of different slider gaps according to the comprehensive cost-effectiveness evaluation model. The slider gap with the highest comprehensive cost-effectiveness index is taken as the optimal theoretical value of slider gap.

[0049] The formula for calculating the performance score P is:

[0050] P = 1.953 × S E −0.844×S R −0.287×S F (10)

[0051] Among them, S E S is the normalized score of energy absorption rate. R S is the normalized score for response time. F The normalized score for fatigue life;

[0052] The comprehensive cost-effectiveness evaluation model is as follows:

[0053] S=1.0498×P−0.02924×C+0.0928 (11)

[0054] Where: S is the overall cost-effectiveness index (dimensionless); P is the performance score; and C is the cost index.

[0055] As a preferred option, in S3.1,

[0056] The specific method for calculating the energy absorption rate E is as follows:

[0057]

[0058] Where δ is the slider clearance, in mm;

[0059] The response time R is the actual data measured under simulated drone impact conditions;

[0060] The specific method for calculating fatigue life is as follows:

[0061] (12)

[0062] in, is the number of stress cycles; C is the material fatigue constant; This is the equivalent stress amplitude;

[0063] ,

[0064] Where q is the fatigue sensitivity coefficient; k t The stress concentration factor; Nominal stress amplitude;

[0065]

[0066]

[0067] Where T is the maximum working torque, in N·m; μ is the coefficient of friction; The contact area of ​​the slider is m. 2 .

[0068] As a preferred option, it also includes,

[0069] S3.3 Verify the manufacturing qualification rate of the optimal theoretical value of slider clearance;

[0070] S3.4 Conduct actual engineering tests on the thermal jamming failure rate, slider life, and maintenance cost indicators of different slider clearances to verify the optimal theoretical value of slider clearance.

[0071] Preferably, in S2, the theoretical maximum and minimum values ​​of the slider clearance are adjusted by preserving assembly margin.

[0072] The formula for calculating assembly margin is:

[0073] (13)

[0074] in, For safety reasons, For the total assembly margin, M t To create a cumulative tolerance margin, For thermal deformation compensation margin, M a These are empirical values ​​for assembly errors;

[0075]

[0076] Among them, T base These are the basic tolerance values ​​based on the ISO 286-1 standard, where n is the number of assembly parts;

[0077]

[0078] in, This is the coefficient of linear expansion of the material. For slider clearance, For working temperature difference;

[0079]

[0080] The adjusted slider gap is: .

[0081] As a preferred embodiment, the method for adjusting the slider gap in S4 is as follows:

[0082] S4.1 Align the centers of the outer telescopic arm and the inner telescopic arm;

[0083] S4.2 Insert a feeler gauge into the gap between the limit slider and the left or right side of the inner telescopic arm, and adjust the bolt group two to adjust the gap between the left or right slider to the optimal theoretical value.

[0084] S4.3 Insert a feeler gauge into the gap between the limit slider and the upper or lower side of the inner telescopic arm, and adjust the bolt group one to adjust the gap between the upper or lower slider to the optimal theoretical value.

[0085] S4.4 Operate the inner and outer telescopic arms to extend and retract, and repeat steps S4.2-S4.3 to make the outer and inner telescopic arms run smoothly.

[0086] S4.5. Retract the inner telescopic arm and use the slider clearance as the initial calibration data. Perform a calibration again periodically during use.

[0087] The present invention has the following beneficial effects:

[0088] 1. This invention proposes a multi-field coupled interval optimization theory for engineering machinery clearance design, encompassing thermodynamics, kinetics, tribology, fatigue life, overall cost, and manufacturing processes. The constructed comprehensive cost-effectiveness evaluation model includes key stability indicators for UAV collision systems, such as energy absorption rate, response time, and fatigue life, and also represents the equilibrium point for multi-objective optimization. This invention calculates the optimal theoretical value of the slider clearance and adjusts the clearance of the limiting slider to this optimal theoretical value. This tiny clearance design limits the range of motion of the telescopic arm during UAV impact, reduces the torsional amplitude of the telescopic arm under lateral force, thereby reducing the risk of cable detachment and significantly improving the performance and reliability of the UAV recovery device. Attached Figure Description

[0089] Figure 1 This is a schematic diagram of a vertical recovery device for drones.

[0090] Figure 2 This is a schematic diagram of the forces acting on a vertical recovery device for a drone.

[0091] Figure 3 This is a schematic diagram showing the connection between the inner telescopic arm and the outer telescopic arm (the outer telescopic arm housing is hidden).

[0092] Figure 4 This is a cross-sectional schematic diagram of the telescopic arm connection structure.

[0093] Figure 5 for Figure 4 A magnified view of a portion of the image.

[0094] in:

[0095] 1. Outer telescopic boom; 2. Inner telescopic boom; 3. Upper crossbar; 4. Lower crossbar; 5. Barrier cable; 6. Bolt group one; 7. Bolt group two; 8. Limiting slider. Detailed Implementation

[0096] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0097] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0098] like Figures 1-5As shown, a method for optimizing the slider gap of a telescopic arm in a UAV vertical recovery device includes the following steps:

[0099] Step S1: Install limit sliders: The UAV vertical recovery device includes n telescopic arms, n≥2. Adjacent telescopic arms are divided into outer telescopic arms and inner telescopic arms. The inner telescopic arm is slidably set inside the outer telescopic arm. Limit sliders are installed between the inner side of the outer telescopic arm head and the inner telescopic arm. Each limit slider is equipped with a position adjustment device to adjust the slider gap.

[0100] In this embodiment, the UAV vertical recovery device includes four telescopic arms, which are, from bottom to top, the first telescopic arm, the second telescopic arm, the third telescopic arm, and the fourth telescopic arm. The fourth telescopic arm is connected to the upper crossbar. For the two adjacent telescopic arms at the top, the fourth telescopic arm is the inner telescopic arm, and the third telescopic arm connected to it is the outer telescopic arm. The four telescopic arms are divided into inner and outer telescopic arms in this manner.

[0101] Each outer telescopic boom is equipped with four limiting sliders between itself and the inner telescopic boom it is connected to. The limiting sliders are L-shaped sliders, which are located at the four corners of the inner side of the boom head of the outer telescopic boom, and the four L-shaped sliders are symmetrically arranged on the left and right.

[0102] The four corners of the inner side of the boom head of the telescopic boom are provided with slider mounting slots. The limit slider is provided with a position adjustment device. The limit slider is fixed to the inner wall of the telescopic boom through the slider mounting slots and the position adjustment device.

[0103] The position adjustment device includes bolt group one and bolt group two. For example... Figure 3 As shown, bolt group one is set above or below the limiting slider. Bolt group one passes through the bolt hole on the outer telescopic arm and connects to the limiting slider to adjust the slider gap between the upper and lower sliders. Bolt group two is set on the left or right side of the limiting slider. Bolt group two passes through the bolt hole on the outer telescopic arm and connects to the limiting slider to adjust the slider gap between the left and right sliders.

[0104] The distance between the inner surface of the limit slider and the outer surface of the inner telescopic arm is the slider clearance. Figure 5 As shown by the L-shaped slider in the upper right corner, the distance between the lower edge of the L-shaped slider and the upper edge of the inner telescopic arm is 'a', and the distance between the left edge of the L-shaped slider and the right edge of the inner telescopic arm is 'b'. Both 'a' and 'b' are the slider gaps of the limit slider.

[0105] Step S2: Calculate the theoretical range of the slider clearance: Through thermodynamic boundary calculation and tribological boundary calculation, obtain the theoretical minimum value δ of the slider clearance. min The theoretical maximum value δ of the slider gap was obtained through dynamic boundary calculations. max The theoretical range of the slider gap [δ] is obtained. min， δ max].

[0106] In this embodiment, the specific calculation process is as follows.

[0107] Step S2.1, Thermodynamic boundary calculation: Calculate the total thermal deformation of the telescopic arm and obtain the theoretical minimum value δ1 of the slider gap that meets the thermodynamic requirements.

[0108] The formula for calculating the total amount of thermal deformation is: (1)

[0109] The formula for calculating δ1 is: δ1 (2)

[0110] Where L is the length of the inner telescopic arm extending beyond the outer telescopic arm, in mm; α is the coefficient of linear expansion of the material, in 1 / ℃; ΔT is the temperature difference of the working environment, in ℃; For safety factor; This represents the total thermal deformation, expressed in mm.

[0111] In this embodiment, all telescopic arms extend to the same length, L = 3020mm, and the coefficient of linear expansion α is taken as 12 × 10 for steel. -6 The operating environment temperature difference is between -10℃ and 40℃, with 50℃ as the acceptable value; safety factor. Based on the empirical value of 1.2, the calculation yields:

[0112] mm.

[0113] mm.

[0114] The minimum theoretical clearance can be adjusted by retaining a certain assembly margin. The formula for calculating the assembly margin is:

[0115] (13)

[0116] in, For safety reasons, For the total assembly margin, M t To create a cumulative tolerance margin, For thermal deformation compensation margin, M a These are empirical values ​​for assembly errors;

[0117]

[0118] Where Tbase is the basic tolerance value based on the ISO286-1 standard, and n is the number of assembly parts;

[0119]

[0120] in This is the coefficient of linear expansion of the material. This is the theoretical value of the slider clearance. For working temperature difference;

[0121]

[0122] Final design gap .

[0123] In this embodiment, δ1 can be adjusted to 1.0mm to retain the assembly margin as described above. At this time, the assembly margin percentage is... It conforms to the ISO286-1:2010 standard.

[0124] Step S2.2, Tribological Boundary Calculation: Calculate the lubricating oil film thickness threshold that meets the engineering life requirements, and calculate the theoretical minimum value δ2 of the slider clearance that meets this threshold; simultaneously calculate the equipment wear rate of the slider clearance, and determine the theoretical minimum value δ2 of the slider clearance that meets both the lubricating oil film thickness requirements and the equipment wear rate requirements; combined with the thermodynamic boundary calculation in step S2.1, obtain the theoretical minimum value of the slider clearance. .

[0125] (1) Calculation of lubricating oil film thickness threshold

[0126] According to the engineering life requirements, the lubricating oil film thickness of the slider should be ≥8μm. The lubricating oil film thickness threshold of 8μm is calculated based on the hydrodynamic lubrication theory, and the calculation formula is as follows:

[0127]

[0128] in:

[0129] k=3.0 is a safety factor, a standard industry value; R q1 R is the root mean square roughness of the slider contact surface. q1 =2μm; R q2 R is the root mean square roughness of the guide rail contact surface. q2 =1μm;

[0130]

[0131] Considering a safety margin of 20%, we get: h threshold =6.72×1.2=8.06μm≈8μm

[0132] (2) Calculation of the theoretical minimum value δ2 of the slider gap

[0133] The relationship between slider clearance and lubricating oil film thickness is as follows: (3)

[0134] in, The thickness of the lubricating oil film (μm); The sliding speed (m / s) is taken as 0.1; The dynamic viscosity of the grease (Pa·s) is taken as 0.15, and 38.07 is the empirically fitted value.

[0135] (3) Calculation of equipment wear rate

[0136] (4)

[0137] Where k is the wear coefficient (2.5 × 10⁻⁶ for nylon compared to steel). -6 P is the contact pressure (MPa); L is the sliding distance (m), taken as 3.020m; H is the material hardness (MPa). This is the oil film thickness correction factor; This is the gap correction factor. ;

[0138] The calculation results are shown in Table 1:

[0139] Table 1. Criteria for Lubricating Oil Film Thickness and Wear Rate Meeting Standards for Different Slider Clearances

[0140] <![CDATA[δ2(mm)]]> (μm) Wear rate (mm / 1000 cycles) 1.0 9.3 0.015 1.2 10.5 0.012 1.5 12.6 0.011

[0141] Based on the theoretical minimum value of slider clearance δ1=1.0mm obtained from the thermodynamic boundary calculation in step S2.1, the lubricating oil film thickness meets the threshold, and the equipment wear rate meets the standard. Therefore, the theoretical minimum value of slider clearance is finally obtained. .

[0142] Step S2.3, Dynamic Boundary Calculation: The theoretical maximum value δ of the slider gap is calculated using the dynamic response model. max Calculations were performed, and the amount of torsional deformation was verified.

[0143] The dynamic response model is as follows:

[0144] Where t is the maximum allowable response time in seconds; a is the slider contact acceleration in m / s².

[0145] In this embodiment, the maximum allowable response time t max Given a time interval of 0.015s and a slider contact acceleration a of 25m / s², the following can be calculated:

[0146] δ max (5)

[0147] The maximum theoretical clearance can also be adjusted while retaining a certain assembly margin. In this embodiment, the maximum theoretical clearance δ is retained. maxThe thickness is 2.0mm, at which point the assembly margin percentage is [missing value]. It conforms to the ISO286-1:2010 standard.

[0148] The torsional deformation was verified using the following calculation formula:

[0149] (6)

[0150] in, The torsion angle is T, the maximum working torque is N·m, and L is the length of the inner telescopic boom extending beyond the outer telescopic boom is m. The shear modulus of the material is expressed in Pa. The polar moment of inertia, in meters. 4 ;

[0151] In this embodiment Therefore, it meets the design requirements.

[0152] The theoretical range of the slider gap can be obtained from the above calculations as [1.0, 2.0] mm.

[0153] Step S3: Calculate the optimal theoretical value of the slider gap: Construct a comprehensive cost-effectiveness evaluation model, calculate the comprehensive cost-effectiveness index of different slider gaps within the theoretical range, and determine the slider gap with the largest comprehensive cost-effectiveness index as the optimal theoretical value.

[0154] In this embodiment, the specific calculation process is as follows.

[0155] Step S3.1: Within the theoretical range, select different slider gaps at certain intervals as test data, calculate the energy absorption rate, response time, and fatigue life corresponding to each slider gap, and perform normalization processing to obtain the normalized score S of the energy absorption rate. E Normalized score of response time S R Normalized score S of fatigue life F .

[0156] (1) Calculate the energy absorption rate E

[0157] Energy absorption rate (E) is a key indicator measuring the efficiency of a telescopic boom system in absorbing and dissipating kinetic energy during a UAV impact, directly related to the system's ability to suppress swaying and prevent cable detachment. Within the theoretical range of the slider clearance, the relationship between energy absorption rate E and slider clearance δ is accurately calculated using the following empirical formula:

[0158]

[0159] This formula is an empirical formula derived from fitting a large amount of experimental data, where the unit of the slider gap δ is mm; it matches the measured data well within the optimization interval δ∈[1.0,2.0]mm.

[0160] δ=1.0 mm:E=8+74×1.0−24×1.02=58%;

[0161] δ=1.5 mm:E=8+74×1.5−24×2.25=65%;

[0162] δ=2.0 mm:E=8+74×2.0−24×4.0=60%.

[0163] The fitted data used in this empirical formula comes from simulated drone impact engineering tests.

[0164] By simulating the drone impact process and measuring the kinetic energy absorbed by the system to calculate the energy absorption rate, the actual performance of different gap optimization schemes can be effectively and accurately evaluated, thereby verifying the correctness of the theoretical calculation results of this invention. The calculation method is as follows:

[0165] The energy absorption rate is defined as the ratio of the energy absorbed by the system to the initial kinetic energy of the impact.

[0166]

[0167] In the formula:

[0168] This represents the portion of energy (J) that the entire UAV vertical recovery device actually absorbs and dissipates during the impact process. Let J be the initial kinetic energy of the drone impact.

[0169] Based on the multi-field coupling theory, the system mainly absorbs energy through the following mechanisms: frictional energy dissipation: the frictional heat generated by the relative sliding of the slider and the telescopic arm; structural deformation energy: the energy stored by the elastic deformation of the telescopic arm system; damping energy dissipation: the energy dissipation generated by the system's internal damping.

[0170] (2) Calculate the response time R

[0171] The response time R is obtained by simulating the impact condition of a drone through actual dynamic testing.

[0172] (3) Calculate fatigue life F

[0173] The fatigue life model is established as follows:

[0174] in, The stress cycle count must meet the requirements according to design standards. The fatigue constant C is 2.5 × 10¹². This is the equivalent stress amplitude;

[0175] ,

[0176] q is the fatigue sensitivity coefficient, which is taken as 0.85; The stress concentration factor; Nominal stress amplitude;

[0177]

[0178]

[0179] T is the maximum working torque, in N·m, taken as 5000; μ is the coefficient of friction, taken as 0.12; The contact area of ​​the slider is m. 2 ;

[0180] In this embodiment, taking δ=1.5mm as an example,

[0181]

[0182]

[0183]

[0184] Fatigue life

[0185] (4) Normalization

[0186] In this embodiment, S E S R S F The normalized scores of these three indicators are based on the minimum-maximum scaling method, using data with dimensions of δ=0.8mm, 1.0mm, 1.5mm, 2.0mm and 2.2mm for testing, and converting indicators of different dimensions into dimensionless scores in the range of [0,1] for comprehensive comparison.

[0187] ① Energy absorption rate (unit: %), normalized formula is:

[0188] (7)

[0189] Among them, E min E represents the minimum energy absorption rate calculated from the test data. max This represents the maximum energy absorption rate calculated from the test data.

[0190] Based on the test data, the minimum value E min=25 (δ=0.8mm), maximum value E max =65 (δ=1.5mm),

[0191]

[0192] ② Response time (unit: ms). Since a smaller response time is better, the normalization formula is:

[0193] (8)

[0194] Among them, R min R is the minimum response time calculated from the test data. max This is the maximum response time calculated from the test data;

[0195] Based on the test data, the minimum value R min =8.1 (δ=1.5mm), R max =18.0 (δ=2.2mm)

[0196]

[0197] ③ Fatigue life (unit: ×10) 7 (times), the normalization formula is:

[0198] (9)

[0199] Among them, F min F represents the minimum fatigue life calculated from the test data. max This represents the maximum fatigue life calculated from the test data.

[0200] Based on the test data, the minimum value F min =0.5 (design threshold, based on the value of δ=1.0mm in Table 3 being close to the threshold), maximum value F max =24.50 (δ=2.0mm),

[0201]

[0202] Step S3.2: Calculate the performance score P and cost index C of different slider gaps within the theoretical range, and obtain the comprehensive cost-effectiveness index of different slider gaps according to the comprehensive cost-effectiveness evaluation model. The slider gap with the highest comprehensive cost-effectiveness index is taken as the theoretical optimal value of slider gap.

[0203] The formula for calculating the performance score P is:

[0204] P = 1.953 × S E −0.844×S R −0.287×S F(10)

[0205] Among them, S E S is the normalized score of energy absorption rate. R S is the normalized score for response time. F The normalized score for fatigue life.

[0206] The weighting coefficients (1.953, -0.844, -0.287) were determined through principal component analysis (PCA) and regression fitting to reflect the contribution of energy absorption rate, response time, and fatigue life to system performance (energy absorption rate is the most important, followed by response time, and fatigue life has a smaller impact).

[0207] The formula for calculating this performance score P is based on multi-field coupled optimization theory. It establishes a comprehensive engineering evaluation model after identifying three key performance indicators: energy absorption rate, response time, and fatigue life. The weighting coefficients in the formula are determined mathematically to ensure that the model output perfectly matches the optimization design objective.

[0208] The comprehensive cost-effectiveness evaluation model is as follows:

[0209] S=1.0498×P−0.02924×C+0.0928 (11)

[0210] Where: S is the comprehensive cost-effectiveness index (dimensionless); P is the performance score; C is the cost index; the cost index C is calculated using the relative cost coefficient method, with the comprehensive cost at δ=2.0mm as the benchmark (C=3.00), and the cost index of other gaps is obtained by relative comparison of the processing difficulty coefficient and the maintenance frequency coefficient.

[0211] This embodiment uses δ=1.0mm, 1.5mm and 2.0mm as examples for calculation.

[0212] (1) δ=1.0mm

[0213] At this point, the energy absorption rate E is 58%; the response time R is 10.2 ms; and the fatigue life F is 5.22 × 10⁻⁶. 7 ;

[0214]

[0215]

[0216]

[0217] Performance score: P1 = 1.953 × 0.825 - 0.844 × 0.7879 - 0.287 × 0.1967 = 0.890

[0218] Cost index C1 = 3.65;

[0219] The overall cost-effectiveness index S1 = 1.0498 × 0.89 − 0.02924 × 3.65 + 0.0928 = 0.92

[0220] (2) δ=1.5mm

[0221] At this point, the energy absorption rate E is 65%; the response time R is 8.1 ms; and the fatigue life F is 13.65 × 10⁻⁶. 7 ;

[0222]

[0223]

[0224]

[0225] Performance score: P2 = 1.953 × 1.0 − 0.844 × 1.0 − 0.287 × 0.5479 = 0.952

[0226] Cost index C2 = 3.14;

[0227] The overall cost-effectiveness index S2 = 1.0498 × 0.952 − 0.02924 × 3.14 + 0.0928 = 1

[0228] (3) δ=2.0mm

[0229] At this point, the energy absorption rate E is 60%; the response time R is 12.0 ms; and the fatigue life F is 24.5 × 10⁻⁶. 7 ;

[0230]

[0231]

[0232]

[0233] Performance score: P3 = 1.953 × 0.875 − 0.844 × 0.6061 − 0.287 × 1.0 = 0.910

[0234] Cost index C3 = 3.0;

[0235] The overall cost-effectiveness index S3 = 1.0498 × 0.91 − 0.02924 × 3.00 + 0.0928 = 0.96

[0236] The calculation results of the comprehensive cost-effectiveness index for different slider clearances are shown in Table 2. The optimal theoretical value of slider clearance is 1.5mm.

[0237] Table 2. Evaluation Table of Comprehensive Cost-Effectiveness Index for Different Slider Clearances

[0238] Slider clearance δ (mm) Performance rating P Cost Index C Value for money (S) 1.0 0.89 3.65 0.92 1.5 0.952 3.14 1.00 2.0 0.91 3.00 0.96 0.5 0.65 4.80 0.35

[0239] When the optimal theoretical value of the slider gap is 1.5mm, the performance score is the highest (0.952): the overall performance is the best among all schemes; the cost-effectiveness is the highest (1.00): the best balance between performance and cost is achieved, which meets the general engineering standards (performance priority, diminishing marginal utility, balance point selection). At this time, the cost-effectiveness index reaches or approaches 1.0, which is a typical "sweet spot" design scheme.

[0240] Step S3.3: Verify the manufacturing qualification rate of the optimal theoretical value of the slider clearance.

[0241] Based on engineering experience

[0242]

[0243] Therefore, it can be concluded that the optimal theoretical value of 1.5mm for the slider clearance is within the range of high yield rates in the manufacturing process, and there is no disadvantage in the manufacturing process.

[0244] In this embodiment, the specific analysis of various indicators for different slider gaps is shown in Table 3.

[0245] Table 3. Analysis of key indicators for different slider clearances

[0246] index δ=1.0mm δ=1.5mm δ=2.0mm threshold Advantages of 1.5mm Thermal stress (MPa) 35 28 22 ≤44 The optimal balance is achieved. 1.0mm results in high thermal stress, while 2.0mm, although the lowest, offers no significant advantage. 1.5mm provides a moderate stress level while ensuring sufficient thermal expansion margin. Response time (ms) 10.2 8.1 12.0 ≤15 Absolutely optimal. This is the core dynamic indicator. 1.5mm has the fastest response, quickly suppressing sway and directly reducing the risk of cable detachment. It is 20% faster than 1.0mm and 48% faster than 2.0mm. Oil film thickness (μm) 9.3 12.3 15.1 ≥8 Sufficient and efficient. A 1.5mm oil film thickness far exceeds the threshold, providing ample lubrication. A 2.0mm film is thicker but offers diminishing returns and may lead to a decrease in dynamic damping. 1.5mm strikes the optimal balance between lubrication and stability. <![CDATA[Fatigue life (×10 7 )]]> 5.22 13.65 24.50 ≥0.5 Fully meets and is excellent. Although the 2.0mm has a longer lifespan, the 13.65 of the 1.5mm is already well over the threshold (more than 27 times), so there are no practical engineering concerns. This can be compromised to optimize other more critical indicators. Cost Index 3.65 3.14 3.00 ≤4.0 Optimal cost-effectiveness. While not the lowest cost, it offers the best value for money. This demonstrates that the small increase in cost for performance improvement yields a significant performance return. Manufacturing pass rate (%) 98 98 98 ≥95 All three are equally excellent. All three are in the high pass rate range, indicating that the 1.5mm diameter does not have any manufacturing process disadvantages.

[0247] 1.5mm has an absolute advantage in the most important response time, the best economy in terms of cost index, fully meets the requirements and is in the high-efficiency range in terms of oil film thickness and fatigue life, and performs well in terms of thermal stress and yield rate. There are no obvious shortcomings. Therefore, the optimal theoretical value of slider clearance is 1.5mm.

[0248] Step S3.4, Engineering Verification: Conduct actual engineering tests on the thermal jamming failure rate, slider life, and maintenance cost of different slider clearances to verify the optimal theoretical value of the slider clearance.

[0249] Table 4 Engineering verification of different slider clearances

[0250] parameter δ=1.0mm δ=1.5mm δ=2.0mm δ=0.8mm (comparison) Advantages of 1.5mm thermal lag failure rate 0 times / 1000h 0 times / 1000h 0 times / 1000h 18 times / 1000h Zero failures. Both 1.0mm and 1.5mm gaps were fault-free, but the 1.0mm gap came at the cost of reduced response speed. The extremely high failure rate of δ=0.8mm demonstrates the disastrous consequences of excessively small gaps. Slider life 8100h 9500h 8700h 3200h The longest service life. This is a direct result of tribological optimization. The 1.5mm diameter has the lowest wear rate (see Table 1), resulting in the longest service life, approximately 1000 hours longer than 1.0mm and 2.0mm. Maintenance costs ($ / year) 4,800 4,500 4,600 9,200 Lowest cost. Thanks to the longest slider life and zero failure rate, 1.5mm has the lowest total lifespan maintenance cost, demonstrating its excellent economic efficiency. Energy absorption rate 58% 65% 60% 25% Absolutely optimal. This is a core safety indicator. 1.5mm can most effectively absorb the impact energy of a drone, minimizing the risk of cable detachment and drone damage. 12% higher than 1.0mm and 8% higher than 2.0mm. Overall cost-performance ratio 0.92 1.00 0.96 0.35 Globally optimal. This index represents the ultimate balance between performance and cost, with 1.5mm being the baseline value of 1.00, fully demonstrating its status as the optimal theoretical value.

[0251] This application also verified the relevant performance indicators for values ​​of 0.8 mm and 2.2 mm outside the slider gap range, and the performance decreased significantly.

[0252] (1) When δ=0.8mm:

[0253] Thermal calorific value ≥120kN (60℃);

[0254] Wear rate: 0.048 mm / 1000 cycles (240% exceeding the standard);

[0255] The manufacturing cost index is 4.8 (28% above the target).

[0256] (2) When δ=2.2mm:

[0257] Response time 18ms (20% over threshold);

[0258] Torsional stiffness decreased to 1580 N·m / deg (a decrease of 47%).

[0259] Fatigue life 3.8×10 7 Second (still meets the standard but the margin is reduced).

[0260] Data analysis reveals that the response time deteriorated by 48% from 1.5mm to 2.0mm (an increase of only 0.5mm); the energy absorption rate decreased by 10.7% from 1.5mm to 1.0mm (a decrease of only 0.5mm); the system performance exhibits a sensitive "critical zone" around 1.5mm; pursuing the lowest cost (δ=2.0mm) sacrifices response speed and energy absorption, directly threatening recovery safety; pursuing the highest fatigue life (δ=2.0mm) and avoiding thermal jamming (δ=1.0mm) sacrifices dynamic performance and economy. The optimal theoretical value of the slider gap achieves a multi-objective coupling effect, simultaneously winning in both energy absorption rate and slider life—two core practical indicators—resulting in the lowest maintenance cost and the highest overall cost-effectiveness, achieving a balance between safety, reliability, economy, and manufacturability.

[0261] When the slider clearance deviates from the optimal theoretical value, there will be a sharp change in engineering risk. As shown in Table 4 and the above calculation results (such as δ=0.8mm or δ=2.2mm), the system will quickly change from "high performance and reliable state" to "high failure rate or performance failure state". This sudden change shows that the optimal theoretical value of slider clearance is a precisely defined engineering optimal solution, rather than a fuzzy "optional range".

[0262] Step S4: Adjust the slider gap: Align the outer telescopic arm and the inner telescopic arm, and adjust the slider gap to the optimal theoretical value of the slider gap using the position adjustment device.

[0263] In this embodiment, the slider gap between all inner telescopic arms and outer telescopic walls is adjusted. The specific adjustment process of the slider gap is as follows.

[0264] S4.1 Align the centers of the outer telescopic arm and the inner telescopic arm; even if L1=L2;

[0265] S4.2 Loosen the bolts of bolt group two, insert a 1.5mm feeler gauge into the gap between the limit slider and the right side of the inner telescopic arm, adjust bolt group two to make the feeler gauge and the limit slider have a certain preload, while ensuring that the feeler gauge can be removed. Remove the feeler gauge, adjust it and fix the adjusting bolt, and adjust the right slider gap b to the optimal theoretical value of 1.5mm.

[0266] The same operation was performed on the gap between the limit slider and the left side of the inner telescopic arm. The gap b of the left slider was also adjusted to the optimal theoretical value of 1.5mm.

[0267] S4.3 Loosen the bolts of bolt group one, insert a 1.5mm feeler gauge into the gap between the limit slider and the upper side of the inner telescopic arm, adjust bolt group two to make the feeler gauge and the limit slider have a certain preload, while ensuring that the feeler gauge can be removed. Remove the feeler gauge, adjust it and fix the adjusting bolt, and adjust the upper slider gap a to the optimal theoretical value of 1.5mm.

[0268] The clearance between the limit slider and the lower side of the inner telescopic arm is adjusted in the same way as above, and the clearance 'a' of the lower slider is also adjusted to the optimal theoretical value of 1.5mm.

[0269] S4.4 Operate the drone's vertical recovery device, slowly extend and retract the inner and outer telescopic arms, observe whether the extension and retraction of the telescopic arms is smooth, whether there are any sudden changes in the pressure on the pressure gauge, and whether there are any abnormal noises during the extension and retraction process. If there are any sudden changes in pressure or abnormal noises, the operation must be stopped immediately, and steps S4.2-S4.3 should be repeated.

[0270] Continue the telescopic movement. If you encounter sudden pressure changes or abnormal noises, handle them as described above until the operation is completely smooth. Observe the operation after telescopic movement at least 3 times to ensure that the outer telescopic arm and the inner telescopic arm operate smoothly.

[0271] S4.5. Retract the inner telescopic arm and use the slider clearance as the initial calibration data. A calibration should be performed every 10 uses thereafter.

[0272] The optimized UAV vertical recovery device proposed in this application can effectively reduce the risk of steel cable detachment, improve the stability of the recovery process, and extend the service life of the device, providing important technical support for the further development of UAV recovery technology.

[0273] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method for optimizing the slider gap of a telescopic arm in a vertical recovery device for unmanned aerial vehicles (UAVs), characterized in that, Includes the following steps: S1. Setting up limiting sliders: The UAV vertical recovery device includes n telescopic arms, n≥2. Two adjacent telescopic arms are divided into an outer telescopic arm and an inner telescopic arm. The inner telescopic arm is slidably set inside the outer telescopic arm. A limiting slider is set between the inner side of the outer telescopic arm head and the inner telescopic arm. Each limiting slider is equipped with a position adjustment device to adjust the slider gap. S2. Calculate the theoretical range of the slider clearance: Through thermodynamic boundary calculations and tribological boundary calculations, obtain the theoretical minimum value δ of the slider clearance. min The theoretical maximum value δ of the slider gap was obtained through dynamic boundary calculations. max The theoretical range of the slider gap [δ] is obtained. min， δ max ]; S3. Calculate the optimal theoretical value of slider clearance: Construct a comprehensive cost-effectiveness evaluation model, calculate the comprehensive cost-effectiveness index of different slider clearances within the theoretical range, and determine the slider clearance with the largest comprehensive cost-effectiveness index as the optimal theoretical value; S4. Adjust the slider gap: Align the outer telescopic arm and the inner telescopic arm, and adjust the slider gap to the optimal theoretical value of the slider gap using the position adjustment device.

2. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 1, characterized in that, In S1, the limit slider is an L-shaped slider, and there are four in total, which are symmetrically arranged on the four corners of the inner side of the arm head of the outer telescopic arm. The position adjustment device includes bolt group one and bolt group two. Bolt group one adjusts the slider gap between the upper and lower limit sliders, and bolt group two adjusts the slider gap between the left and right limit sliders.

3. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 1, characterized in that, In S2, the specific method for calculating the thermodynamic boundary is as follows: Calculate the total thermal deformation ; （1） Where L is the length of the inner telescopic arm extending beyond the outer telescopic arm, in mm; α is the coefficient of linear expansion of the material, in 1 / ℃; ΔT is the temperature difference of the working environment, in ℃; This represents the total thermal deformation, expressed in mm. Calculate the theoretical minimum value δ1 of the slider gap that meets the thermodynamic requirements; d1 (2) in, This is for the safety factor.

4. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 3, characterized in that, In S2, the specific method for calculating the tribological boundary is as follows: Calculate the threshold of lubricating oil film thickness that meets the engineering life requirements, and calculate the theoretical minimum value δ2 of slider clearance that meets this threshold. The formula for calculating the thickness of the lubricating oil film for different slider clearances is as follows: （3） in, The thickness of the lubricating oil film is in μm. The sliding speed is expressed in m / s. The dynamic viscosity of the grease is Pa·s; Calculate the equipment wear rate for different slider clearances to determine whether the equipment wear rate meets the standard. （4） Where k is the wear coefficient; P is the contact pressure (MPa); L is the sliding distance (m); and H is the material hardness (MPa). This is the oil film thickness correction factor; The theoretical minimum value δ2 of the slider clearance was obtained, which ensured that the equipment wear rate met the standard and the lubricating oil film thickness requirement. By combining thermodynamic boundary calculations, the theoretical minimum value of the slider gap is obtained. .

5. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 1, characterized in that, In S2, the specific method for calculating the dynamic boundary is as follows: The theoretical maximum value δ of the slider clearance is calculated based on the corresponding dynamic model. max And the torsional deformation was verified. d max (5) Among them, t max The maximum allowable response time is expressed in seconds (s); a is the slider contact acceleration, expressed in m / s². The formula for calculating torsional deformation is as follows: （6） in, The torsion angle is T, the maximum working torque is N·m, and the telescopic boom length is m. The shear modulus of the material is expressed in Pa. The polar moment of inertia, in meters. 4 .

6. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 1, characterized in that, In S3, the specific method for calculating the overall cost-effectiveness index is as follows: S3.

1. Within the theoretical range, select different slider gaps at certain intervals as test data, calculate the energy absorption rate E, response time R, and fatigue life F corresponding to each slider gap, and perform normalization processing to obtain the normalized score S of the energy absorption rate. E Normalized score of response time S R Normalized score S of fatigue life F ; The normalized formula for energy absorption rate is: （7） Among them, E min E represents the minimum energy absorption rate calculated from the test data. max This represents the maximum energy absorption rate calculated from the test data. The normalization formula for response time is: （8） Among them, R min R is the minimum response time calculated from the test data. max This is the maximum response time calculated from the test data; The normalized formula for fatigue life is: （9） Among them, F min F represents the minimum fatigue life calculated from the test data. max This represents the maximum fatigue life calculated from the test data. S3.2 Calculate the performance score P and cost index C of different slider gaps within the theoretical range, and obtain the comprehensive cost-effectiveness index of different slider gaps according to the comprehensive cost-effectiveness evaluation model. The slider gap with the highest comprehensive cost-effectiveness index is taken as the optimal theoretical value of slider gap. The formula for calculating the performance score P is: P=1.953×S E −0.844×S R −0.287×S F (10) Among them, S E S is the normalized score of energy absorption rate. R S is the normalized score for response time. F The normalized score for fatigue life; The comprehensive cost-effectiveness evaluation model is as follows: S=1.0498×P−0.02924×C+0.0928 (11) Where S is the overall cost-effectiveness index (dimensionless); P is the performance score; and C is the cost index.

7. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 6, characterized in that, In S3.1, The specific method for calculating the energy absorption rate E is as follows: ； Where δ is the slider clearance, in mm; The specific method for calculating fatigue life is as follows: （12） in, C is the number of stress cycles; C is the material fatigue constant. This is the equivalent stress amplitude; ， Where q is the fatigue sensitivity coefficient; k t The stress concentration factor; Nominal stress amplitude; ； ； Where T is the maximum working torque, in N·m; μ is the coefficient of friction; m is the contact area of ​​the slider. 2 .

8. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 6, characterized in that, It also includes, S3.3 Verify the manufacturing qualification rate of the optimal theoretical value of slider clearance; S3.4 Conduct actual engineering tests on the thermal jamming failure rate, slider life, and maintenance cost indicators of different slider clearances to verify the optimal theoretical value of slider clearance.

9. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 1, characterized in that, In S2, the theoretical maximum and minimum values ​​of the slider clearance are adjusted by preserving assembly margin. The formula for calculating assembly margin is: （13） in, For safety reasons, For the overall assembly margin, M t To create a cumulative tolerance margin, For thermal deformation compensation margin, M a These are empirical values ​​for assembly errors; ； Among them, T base These are the basic tolerance values ​​based on the ISO 286-1 standard, where n is the number of assembly parts; ； in, is the coefficient of linear expansion of the material. For slider clearance, For working temperature difference; ； The adjusted slider gap is: .

10. The method for optimizing the slider gap of the telescopic arm of a UAV vertical recovery device according to claim 2, characterized in that, In S4, the specific method for adjusting the slider gap is as follows: S4.1 Align the centers of the outer telescopic arm and the inner telescopic arm; S4.2 Insert a feeler gauge into the gap between the limit slider and the left or right side of the inner telescopic arm, and adjust the bolt group two to adjust the gap between the left or right slider to the optimal theoretical value. S4.3 Insert a feeler gauge into the gap between the limit slider and the upper or lower side of the inner telescopic arm, and adjust the bolt group one to adjust the gap between the upper or lower slider to the optimal theoretical value. S4.4 Operate the inner and outer telescopic arms to extend and retract, and repeat steps S4.2-S4.3 to make the outer and inner telescopic arms run smoothly. S4.

5. Retract the inner telescopic arm and use the slider clearance as the initial calibration data. Perform a calibration again periodically during use.

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