A method and system for suppressing vibration of a drone suspended in transport

Abstract

The present application provides a kind of unmanned aerial vehicle hanging transport vibration suppression method and system, and vibration suppression method includes: the swing state parameter of real-time acquisition hanging load;The swing state parameter is compared with preset safety threshold;When the swing amplitude exceeds the preset safety threshold, the required cable stiffness adjustment amount is calculated according to the swing state parameter, and the energization control instruction for the electroactive deformation section arranged in the cable main body is generated, to change the axial dimension of the electroactive deformation section, so as to adjust the axial elastic coefficient of the cable to suppress the swing of the hanging load;When the swing amplitude falls below the preset safety threshold, the power-off instruction is generated to restore the initial size of the electroactive deformation section.The present application adjusts the elastic coefficient of the electroactive deformation section arranged in the cable main body on-line dynamically, and calculates the optimal stiffness adjustment amount, so as to avoid disturbance frequency, realize the rapid, adaptive suppression of the swing of the hanging load.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) sling transport technology, and in particular to a method and system for vibration suppression during unmanned aerial vehicle (UAV) sling transport. Background Technology

[0002] Due to its flexibility and efficiency, drone-borne transport has broad application prospects in fields such as material delivery and emergency rescue. However, the connection between the drone and the load is made through a flexible cable, forming an underactuated system. Acceleration and deceleration during flight, as well as gusts of wind, can easily induce periodic oscillations in the load. This oscillation not only affects flight stability but also poses a huge challenge to precise delivery and obstacle avoidance control. To compensate for the shortcomings of simple flight control yaw suppression, those skilled in the art have turned to improving the suspension connection structure. For example, they have increased the horizontal stiffness of the system by adding lateral constraints, or added magnetorheological dampers or mechanical friction hinges in an attempt to accelerate convergence by dissipating yaw energy. The above-mentioned structural improvement schemes have shown a certain yaw reduction effect under specific operating conditions, but most of them belong to the passive or semi-active category. Their structural parameters (such as damping coefficient and cable configuration angle) cannot be changed online once set. When the weight and size of the suspended load change significantly, or when the flight conditions switch between hovering, level flight and emergency stop, the yaw suppression performance of these fixed parameter devices will decrease sharply, making it difficult to achieve adaptive vibration suppression across the entire operating condition range. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the prior art. The present invention provides a method and system for suppressing vibration of UAV sling transport. By twisting an electro-deformable joint into the main body of the cable, the elastic coefficient is dynamically adjusted online, and the optimal stiffness adjustment amount is calculated, thereby avoiding the disturbance frequency and realizing rapid and adaptive suppression of the swing of the sling load.

[0004] On the one hand, in order to solve the above-mentioned technical problems, the present invention provides a method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport, comprising: S1: Real-time acquisition of the swing state parameters of the suspended load; S2: Compare the swing state parameters with a preset safety threshold; S3: When the swing amplitude exceeds the preset safety threshold, calculate the required cable stiffness adjustment amount according to the swing state parameters, and generate an energizing control command for the electro-deformable joint set on the cable body. S4: Execute the power-on control command to change the axial dimension of the electro-deformable joint, thereby adjusting the axial elastic coefficient of the cable to suppress the sway of the suspended load; S5: When the swing amplitude falls below the preset safety threshold, a power-off command is generated to restore the initial size of the electro-deformable joint.

[0005] Furthermore, the specific method for obtaining the swing state parameters of the suspended load in real time in step S1 is as follows: The specific method for obtaining the swing state parameters of the suspended load in real time is as follows: Extract image sequences; Calculate the single-axis swing angle of the suspended load at the current moment based on the image sequence. and angular velocity of oscillation And identify the maximum swing angle amplitude within the swing period. ; Based on multiple consecutive cycles The rate of change determines whether the current oscillation is in the divergence or convergence phase.

[0006] Furthermore, in step S3, the specific method for calculating the required cable stiffness adjustment based on the swing state parameters is as follows: Calculate the current natural frequency of the suspended load. :

[0007] in, It is the acceleration due to gravity. This is the original length of the cable. This is the static elongation of the cable. For the suspended load mass, This is the equivalent elastic coefficient of the current cable; Calculate the real-time dominant oscillation frequency :

[0008] in, To prevent division by zero minimum constant; Calculate the frequency offset potential function Quantify the energy distance between the current oscillation state and the resonance state:

[0009] in, For frequency difference, This is the stiffness adjustment gain coefficient. The preset minimum safe frequency difference threshold, Used as the reference swing angle constant; Based on the frequency offset potential function Calculate the required cable target stiffness adjustment for the negative gradient direction of stiffness. This causes the system to move away from the resonant state along the direction in which the potential function decreases most rapidly at the stated frequency; whereby... The expression is as follows: ;) Furthermore, the specific method for generating the power-on control command in step S3 is as follows: Based on the electrostatic actuation characteristics of electrodeformable materials, the required energizing voltage is established. With target stiffness adjustment amount Mapping relationship between them:

[0010] in, The initial wall thickness of the electro-deformable joint is given. The Young's modulus of the material. The vacuum permittivity, The relative permittivity, The effective area of ​​the electrode. A geometric factor characterizing the deformation transfer efficiency of a cable braided structure; like When the value is positive, the controller outputs the voltage. To increase stiffness by causing the electro-deformable joint to contract; like When the value is negative, the controller outputs a preset bias voltage to put the electro-deformable joint in a semi-activated state to reduce its stiffness.

[0011] Furthermore, when the cable body contains When generating an axially distributed electrodeformable section, the method for generating an energizing control command further includes: Adjustment based on the current target stiffness Calculate the number of electrodeformable nodes to be activated :

[0012] in, This represents the standard stiffness increment produced by a single electrocaustic joint at rated voltage. Indicates rounding up; Starting with the first section closest to the drone platform, proceed sequentially towards the next... The voltage is applied to each electro-deformable section. This is to generate a continuous stiffness gradient distribution.

[0013] Furthermore, during the execution of the power-on control command, the frequency offset potential function is continuously calculated. The gradient, when detected and hour If it is determined that the suspended load has left the resonance sensitive area, a power-off command is executed to restore the initial size of the electro-deformable joint; Where ξ is the preset gradient convergence threshold, The preset security threshold is defined as follows.

[0014] Secondly, in order to solve the above-mentioned technical problems, the present invention provides a drone sling transport system, comprising: Unmanned aerial vehicle (UAV) platform; A variable stiffness cable, one end of which is connected to the UAV platform; the variable stiffness cable includes a cable body and at least one electro-deformable joint wound into the cable body; The mounting mechanism, connected to the other end of the variable stiffness cable, is used to connect and suspend the load; A visual monitoring unit is installed near the mounting mechanism to collect image data of the swing state of the suspended load. A controller, mounted on the UAV platform, is electrically connected to the visual monitoring unit and the electro-deformation energy-saving device; the controller is configured to perform the vibration suppression method according to any one of claims 1 to 6.

[0015] Furthermore, the electro-deformable joint comprises, from the inside out: a safety load-bearing core, an electro-deformable sleeve, a flexible conductive outer layer, and an outer insulating sheath; both ends of the electro-deformable joint are fixedly connected to the cable body through mechanical connectors, and the flexible conductive outer layer is electrically connected to the controller through wires.

[0016] Furthermore, the electrodeformable sleeve is made of a copolymer dielectric elastomer, which contracts axially when a voltage is applied by the controller and returns to its original length when the voltage is cut off.

[0017] Furthermore, the controller controls the energization and contraction of different numbers of electro-deformable joints based on the swing amplitude of the suspended load.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport as described in this invention monitors the swing state of the sling load in real time and dynamically adjusts the elastic coefficient of the cable to actively change the natural frequency of the sling load to avoid the disturbance frequency, thereby achieving rapid and adaptive suppression of the sling load swing. It does not rely on flight control attitude adjustment or mechanical damping energy consumption, has a fast swing suppression intervention speed, and has a significant suppression effect on sudden gust disturbances.

[0019] 2. The UAV sling transport system described in this invention uses an electro-deformable joint as the active adjustment unit of the cable. This material generates a contraction response under the drive of an electric field, enabling the elastic coefficient of the entire cable to switch in a very short time. Once the visual monitoring unit detects that the swing angle exceeds the limit, the controller can immediately change the system stiffness and actively destroy the resonance condition. Compared with the method of relying on flight control attitude adjustment or mechanical damping energy consumption, the swing intervention speed is faster and the suppression effect on sudden gust disturbances is particularly significant.

[0020] 2. The UAV sling transport system described in this invention comprehensively considers the instantaneous deviation between the system's natural frequency and the real-time disturbance frequency, as well as the dynamic influence of the current swing angle amplitude. Regardless of changes in the weight and aerodynamic shape of the sling load, the controller can automatically calculate the required target stiffness adjustment and corresponding drive voltage based on real-time visual feedback, truly achieving adaptive control for load changes and flight condition changes, and overcoming the poor adaptability of existing fixed-parameter swing reduction devices.

[0021] 3. The UAV sling transport system described in this invention integrates multiple independently controllable electro-deformable joints along the axial direction within a variable stiffness cable. The controller activates the corresponding number of deformable joints as needed based on the calculated stiffness adjustment, achieving graded sway suppression and avoiding unnecessary energy waste. Simultaneously, by employing a strategy of sequential energization from the near end to the far end, a continuous stiffness gradient transition is formed on the cable, effectively mitigating the risk of stress concentration and fatigue fracture that may be caused by random movements of local segments.

[0022] 4. This invention does not require large-scale modifications to the main structure of the UAV platform or the flight control system hardware. The visual monitoring unit can be a lightweight miniature camera, and the controller reuses the existing onboard computing resources of the UAV. The weight increase of the entire system is minimal and does not affect the UAV's payload capacity and endurance. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the structure of the UAV sling transport system in a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the variable stiffness cable in an embodiment of the present invention; Figure 3 This is a schematic flowchart of the vibration suppression method in an embodiment of the present invention; Explanation of reference numerals in the accompanying drawings: 1. Unmanned aerial vehicle platform; 2. Variable stiffness cable; 3. Mounting mechanism; 4. Suspended load; 5. Controller; 6. Visual monitoring unit; 21. Cable body; 22. Electrodeformable joint; 221. External insulating sheath; 222. Flexible conductive outer layer; 223. Electrodeformable sleeve; 224. Safety load-bearing core. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0026] Example 1: like Figure 1 As shown, the present invention provides a drone sling transport system, comprising: Unmanned aerial vehicle platform 1; Variable stiffness cable 2, one end of which is connected to the UAV platform 1; The mounting mechanism 3 is connected to the other end of the variable stiffness cable 2 and is used to connect and suspend the load 4. The visual monitoring unit 6 is installed near the mounting mechanism 3 and is used to collect real-time image data of the swing state of the suspended load 4. Controller 5 is installed on UAV platform 1 and electrically connected to visual monitoring unit 6; The variable stiffness cable 2 includes a cable body 21 and at least one electro-deformable joint 22 disposed on the cable body 21. The electro-deformable joint 22 is electrically connected to the controller 5. The controller 5 controls the energization state of the electro-deformable joint 22 based on the swing state image data to dynamically change the axial elastic coefficient of the variable stiffness cable 2.

[0027] Preferably, the electrodeformable joint 22 comprises, from the inside out: a safety load-bearing core 224, an electrodeformable sleeve 223, a flexible conductive outer layer 222, and an outer insulating sheath 221. Both ends of the electrodeformable joint 22 are fixedly connected to the cable body 21 via mechanical connectors, and the flexible conductive outer layer 222 is electrically connected to the controller 5 via wires. The safety load-bearing core 224 provides redundant load-bearing capacity in the event of failure of the electrodeformable sleeve 223, ensuring that the suspended load 4 will not fall. The flexible conductive outer layer 222 and the outer insulating sheath 221 form a double-layer electrical safety protection, adapting to the complex electromagnetic environment of UAV outdoor operations. The mechanical connectors at both ends ensure reliable force transmission between the electrodeformable joint and the cable body 21. The overall structure is compact and easily integrated into existing cable manufacturing processes.

[0028] The electrodeformable sleeve 223 is made of P(LA-VK) copolymer dielectric elastomer, which contracts axially when voltage is applied by the controller 5 and returns to its original length when the voltage is cut off. The P(LA-VK) copolymer dielectric elastomer generates a rapid axial contraction response under the drive of an electric field, enabling the elastic coefficient of the entire cable to switch in a very short time. After the power is cut off, the material automatically returns to its initial length by its own elastic restoring force, without the need for an additional reset mechanism, which simplifies the system structure and control logic. Compared with magnetorheological or mechanical variable stiffness solutions, it has a faster response speed, lighter weight, and no mechanical wear.

[0029] When the controller 5 applies voltage to the flexible conductive outer layer 222, a strong electric field is formed in the thickness direction of the electrodeformable sleeve 223, and the thickness direction of the material is compressed, thereby elongating or contracting along the axial direction (length direction). When the electrodeformable sleeve 223 is energized, it exhibits axial contraction behavior, thereby tightening the entire cable and increasing its equivalent elastic coefficient. When the controller 5 cuts off the power supply voltage, the electric field disappears, and the electrodeformable sleeve 223 recovers to its initial length by relying on the elastic restoring force of the material itself. The elastic coefficient of the entire cable then recovers to its initial value.

[0030] The controller 5 controls the energization and contraction of different numbers of electro-deformable joints 22 according to the swing amplitude of the suspended load 4.

[0031] In this embodiment, the cable body 21 of the variable stiffness cable 2 may contain multiple electro-deformable sections 22 distributed axially at intervals. Each electro-deformable section 22 is electrically connected to the output port of the controller 5 through an independent wire channel. The controller 5 selects and controls the corresponding number of electro-deformable sections 22 to be energized and contracted simultaneously according to the real-time swing amplitude (such as the maximum swing angle) of the suspended load 4 calculated by the visual monitoring unit 6. For example, when the swing amplitude is small, only one or two electro-deformable joints 22 are controlled to operate to provide a small stiffness increment; When encountering strong gusts or motorized movements that cause large sway amplitudes, the controller 5 controls more or even all of the electro-deformable joints 22 to be energized simultaneously to provide a larger stiffness change gradient and quickly suppress large sway.

[0032] Example 2: like Figure 3 As shown, the present invention provides a method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport, comprising: S1: Real-time acquisition of the swing state parameters of the suspended load 4 collected by the visual monitoring unit 6; S2: Determine whether the current swing amplitude exceeds the preset safety threshold based on the swing state parameters; S3: If the preset safety threshold is exceeded, the required cable stiffness adjustment amount is calculated based on the swing state parameters, and an energizing control command is generated for the electro-deformable joint 22. S4: Execute the power-on control command to change the axial dimension of the electro-deformable joint 22, thereby adjusting the overall elastic coefficient of the variable stiffness cable 2 to suppress the swaying of the suspended load 4. S5: When the swing amplitude is detected to fall below the preset safety threshold, a power-off command is generated to restore the initial size of the electro-deformable section 22.

[0033] Specifically, after the system is powered on and initialized, the visual monitoring unit 6 continuously acquires image data of the suspended load 4 at a fixed frame rate, and the controller 5 calculates the parameters characterizing the swing state of the suspended load 4 in real time through the image processing algorithm. The controller 5 compares the swing state parameters (such as the current maximum swing angle amplitude) obtained in step S1 with the preset safety threshold in the internal memory. If the swing amplitude does not exceed the threshold, it indicates that the system is in a stable state or a state of slight disturbance. The controller 5 does not output an action command, and the visual monitoring unit 6 continues to monitor. Once it is determined that the swing amplitude exceeds the safety threshold, the system immediately enters the active swing suppression mode. The controller 5 calls the built-in stiffness adjustment calculation algorithm to obtain the target stiffness value that needs to be adjusted, and calculates the voltage amplitude and energizing time to be applied based on the electromechanical coupling model of the electrodeformable material. The drive circuit of the controller 5 outputs a corresponding voltage signal, causing the electrodeformable section 22 to contract axially, changing the elastic coefficient of the entire variable stiffness cable 2, and thus changing the dynamic characteristics of the system. This disrupts the original resonance conditions or weakens the input of disturbance energy, achieving rapid suppression of sway. During the adjustment process, the controller 5 continuously performs monitoring steps. When it is determined that the sway amplitude has fallen below the preset safety threshold and tends to stabilize, the controller 5 outputs a power-off command to cut off the voltage applied to the electrodeformable section 22. The electrodeformable section 22 returns to its initial length, the variable stiffness cable 2 returns to its basic elastic coefficient, and the system returns to the initial passive suspension state, waiting for the next trigger.

[0034] The process of acquiring the swing state parameters of the suspended load in real time, collected by the visual monitoring unit, includes: Extract the image sequence acquired by the visual monitoring unit and calculate the single-axis swing angle of the suspended load 4 at the current moment. and angular velocity of oscillation And identify the maximum swing angle amplitude within the swing period. ; Based on multiple consecutive cycles The rate of change determines whether the current oscillation is in the divergence or convergence phase. Based on the rate of change of the maximum swing angle amplitude over multiple consecutive cycles, the swing trend can be identified in advance. This allows for early prediction of whether the system is in a negative damping divergence state, providing a basis for the controller 5 to adjust in advance and avoiding passively waiting for the swing angle to exceed the limit before responding.

[0035] It should be noted that the visual monitoring unit 6 transmits the image sequence of the suspended load 4 (or the feature markers set on the mounting mechanism 3) to the controller 5; the controller 5 first tracks the pixel coordinate changes of the target point in the image plane using the feature point matching method, and combines the known camera intrinsic parameters and the geometric relationship of the suspension length to convert the pixel displacement into the real-time single-axis swing angle of the suspended load 4 in the spherical coordinate system. The real-time oscillation angular velocity is obtained by performing a differential operation on time. Meanwhile, controller 5 maintains a sliding time window, monitors and updates the maximum swing angle within the window in real time, and records it as the maximum swing angle amplitude of the current cycle. To predict the oscillation trend, controller 5 compares data from multiple consecutive oscillation cycles. The rate of change; if An increasing trend indicates that the oscillation is in a divergent phase, the system is in a negative damping state, and strong intervention is required; if The decrease has begun, indicating that the system is in the convergence phase, and the adjustment amount can be appropriately reduced.

[0036] The method for calculating the required cable stiffness adjustment based on the swing state parameters includes: Calculate the current natural frequency of the suspended load 4. :

[0037] in, It is the acceleration due to gravity. This is the original length of the cable. This is the static elongation of the cable. For the suspended load mass, This is the equivalent elastic coefficient of the current cable; Calculate the real-time dominant oscillation frequency :

[0038] in, To prevent division by zero minimum constant; Calculate the frequency offset potential function Quantify the energy distance between the current oscillation state and the resonance state:

[0039] in, For frequency difference, This is the stiffness adjustment gain coefficient. The preset minimum safe frequency difference threshold, Used as the reference swing angle constant; Based on frequency offset potential function Calculate the required cable target stiffness adjustment for the negative gradient direction of stiffness. , This causes the system to move away from the resonance state along the direction in which the frequency offset potential function decreases the fastest.

[0040] It should be noted that traditional control methods often only make proportional adjustments based on the swing angle error, which can cause the system to overshoot or oscillate at the resonance edge. This embodiment transforms the swing suppression control into a problem of finding the optimal direction for the potential function to decrease by constructing an energy potential function related to the frequency difference and swing amplitude. Specifically, the natural frequency of the suspended load 4 Used to describe the physical characteristics of a suspension system. The manufacturing length of the variable stiffness cable 2 in the unstressed state; The load is determined by the weight of the suspended load and the current elasticity coefficient of the cable. The static elongation, which is determined by both factors, can be calculated based on the current height and angle of the suspended load 4. Given the known mass of the suspended load 4; the first half of the formula The latter half is used to characterize the gravitational stiffness term of a simple pendulum. Used to characterize the elastic stiffness of the cable; through calculation The controller 5 can determine the frequency points where the system is currently prone to resonance; Real-time oscillation dominant frequency Used to estimate the dominant frequency of external disturbances or the current motion of the system; It is the instantaneous angular velocity. The amplitude of the current period; a minimal constant is introduced into the denominator. Used to prevent calculation overflow; this ratio reflects the current speed of the sway. Frequency offset potential function This represents the energy barrier height of the system's current state relative to the safe state; in the formula, It is the instantaneous difference between the natural frequency and the disturbance frequency; when The absolute value is less than the preset safety frequency difference threshold. When, the item in parentheses A negative value indicates that the system has entered a dangerous resonant attraction region, and the potential function value decreases; simultaneously, an exponential term is introduced. As an adaptive weighting factor, when the swing angle When the angle is small, this value is close to 1, and the adjustment behavior is relatively smooth. When the value increases, the value of this term decreases, causing the potential function to become more sensitive to frequency differences, thereby accelerating the control response. To adjust the global gain, the controller's response to frequency deviation is determined. The preferred value range for the intensity of the response is 0.5-2.0; More preferably, fine-tuning can be performed before delivery via a step disturbance test, i.e., applying a standard horizontal thrust to the stationary suspended load 4 and observing different... The time required for the swing angle to decay to 5% of its initial value is selected, choosing the option with the shortest convergence time and no overshoot oscillations. The value is used as the final set value; To calibrate the swing angle, the sensitivity of the potential function is nonlinearly scaled, so that the system responds more quickly at large swing angles and more smoothly at small swing angles. The value and the preset security threshold Relatedly, to ensure that the system can provide a sufficiently large adjustment gain when the swing angle exceeds the safety threshold, while avoiding overly abrupt adjustment actions at small swing angles, Set to slightly less than the preset safety threshold ; The system needs to change the stiffness To change the natural frequency Thus affecting Ultimately, it escapes the trap of the potential function; therefore, controller 5 calculates the potential function. Regarding stiffness The partial derivatives are used to determine the adjustment amount along its negative gradient direction (i.e., the opposite direction of the fastest descent of the potential function); expanding the partial derivatives yields: After taking the negative sign, we get the final formula. That is, if the current natural frequency is greater than the disturbance frequency ( If >0), then A negative value will decrease the cable stiffness to lower the natural frequency, while a positive value will increase the stiffness; the magnitude of the adjustment is affected by the amplitude of the swing. Modulation was used to achieve nonlinear adaptive control.

[0041] The generation of energizing control commands for the electro-deformable joint also includes: Based on the electrostatic actuation characteristics of electrodeformable materials, the required energizing voltage is established. With target stiffness adjustment amount Mapping relationship between them:

[0042] in, The initial wall thickness of the electro-deformable joint 22 is given. The Young's modulus of the material. The vacuum permittivity, The relative permittivity, The effective area of ​​the electrode. A geometric factor characterizing the deformation transfer efficiency of a cable braided structure; like When the value is positive, the controller output voltage The electro-deformable joint contracts to increase stiffness; if When the value is negative, the controller outputs a preset bias voltage to keep the electro-deformable joint in a semi-activated state to reduce its stiffness.

[0043] Preferred, Take the initial wall thickness of the electrodeformable sleeve 223. The Young's modulus of P(LA-VK) material under zero electric field. The relative permittivity of P(LA-VK) material can be measured using an impedance analyzer; Effective electrode area covered by the flexible conductive outer layer 222; geometric factor It is used to correct the loss of axial force transmission caused by the cable braided spiral structure. Its value is determined by the cable braiding angle and the strand friction coefficient, usually between 0.6 and 0.95, and can be pre-stored in the controller 5 through calibration experiments.

[0044] In this embodiment, the electrostatic pressure generated by the external voltage balances the elastic restoring force of the material. By controlling the voltage, the shrinkage strain can be precisely controlled, thereby controlling the change in equivalent stiffness. If the calculated... If the value is positive (stiffness needs to be increased), the output circuit of controller 5 applies a voltage corresponding to the calculated value. If the calculated A negative value (stiffness needs to be reduced) is required because the dielectric elastomer is in its softest state at zero voltage. Further reducing stiffness requires it to be in a pre-stretched relaxation state. Therefore, when stiffness needs to be reduced, the controller 5 does not apply a negative voltage, but rather a lower preset bias voltage, so that the electro-deformable joint 22 is in a semi-activated contraction preparation state, thereby allowing the cable to generate a larger dynamic elongation when swinging and stretching, which is equivalent to reducing the overall dynamic stiffness of the system.

[0045] Among them, when the main body of the cable contains When generating an axially distributed electro-deformable section, the energizing control command also includes: Adjustment based on the current target stiffness Calculate the number of electrodeformable nodes to be activated :

[0046] in, This represents the standard stiffness increment produced by a single electrocaustic joint under rated voltage. Indicates rounding up; Controller 5 starts from the first section closest to the UAV platform and proceeds sequentially to the next section. Voltage is applied to each electro-deformable section. This is to generate a continuous stiffness gradient distribution and avoid sudden changes in local stress in the cable.

[0047] Specifically, in order to provide a wider range of stiffness adjustment in long-distance suspension, the variable stiffness cable 2 integrates... The controller 5 employs a hierarchical control strategy during execution, first determining the standard unit stiffness increment of a single electrodeformable section 22 under rated operating voltage. This value is determined through a prior calibration experiment and stored in the register of controller 5; after obtaining the total target adjustment amount... Then, controller 5 calculates the number of sections that need to be activated. This means dividing the total demand by the unit increment and rounding up to ensure sufficient adjustment. After determining the number of activations, controller 5 employs a sequential activation strategy, starting with the first electrodeformable segment 22 that is physically closest to the UAV platform 1 (i.e., the top of the cable), and proceeding sequentially to the next segment in the sequence. Each electro-deformable joint 22 is simultaneously subjected to the same control voltage. This sequential activation method allows the cable stiffness change to transition smoothly from top to bottom, forming a continuous stiffness gradient. This effectively avoids stress concentration and excessive bending caused by random movement of local segments, thus improving the cable's fatigue life and safety.

[0048] During the execution of the power-on control command, the controller continuously calculates the frequency offset potential function. The gradient, when detected and When it is determined that the suspended load 4 has left the resonance sensitive area, a power-off command is then executed to restore the initial size of the electro-deformable joint; in The preset gradient convergence threshold, This is a preset safety threshold.

[0049] Specifically, to prevent the controller 5 from prematurely exiting or repeatedly oscillating during vibration suppression, this embodiment sets strict exit criteria. During the power-on adjustment in step S4, the controller 5 does not simply wait for the swing angle to be less than the threshold, but simultaneously monitors the change in the potential function gradient; the controller 5 calculates the absolute value of the frequency-shifted potential function gradient term in real time at the same sampling frequency. The controller 5 determines that the suspended load 4 has truly left the resonance danger zone and entered a stable convergence state only when both of the following conditions are met simultaneously: Condition one: This condition indicates that the currently calculated required stiffness adjustment is already extremely small, meaning that the difference between the system's natural frequency and the disturbance frequency is already sufficiently large (far greater than the safety threshold). The potential function terrain tends to be flat, so continuing to apply power for adjustment is unnecessary and may introduce additional noise. Condition two: This condition serves as a direct safety indicator, ensuring that the absolute swing angle of the suspended load 4 has returned to the permissible safe operating range. Once the above two conditions are met simultaneously, the controller 5 immediately executes step S5, outputs a power-off command, cuts off the power supply to all electro-deformable joints 22, and the system returns to the initial passive suspension state, completing a complete adaptive sway-damping closed-loop control cycle.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport, characterized in that, include: S1: Real-time acquisition of the swing state parameters of the suspended load; S2: Compare the swing state parameters with a preset safety threshold; S3: When the swing amplitude exceeds the preset safety threshold, calculate the required cable stiffness adjustment amount according to the swing state parameters, and generate an energizing control command for the electro-deformable joint set on the cable body. S4: Execute the power-on control command to change the axial dimension of the electro-deformable joint, thereby adjusting the axial elastic coefficient of the cable to suppress the sway of the suspended load; S5: When the swing amplitude falls below the preset safety threshold, a power-off command is generated to restore the initial size of the electro-deformable joint.

2. The method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport according to claim 1, characterized in that, The specific method for obtaining the swing state parameters of the suspended load in real time in step S1 is as follows: The specific method for obtaining the swing state parameters of the suspended load in real time is as follows: Extract image sequences; Calculate the single-axis swing angle of the suspended load at the current moment based on the image sequence. and angular velocity of oscillation And identify the maximum swing angle amplitude within the swing period. ; Based on multiple consecutive cycles The rate of change determines whether the current oscillation is in the divergence or convergence phase.

3. The method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport according to claim 1, characterized in that, In step S3, the specific method for calculating the required cable stiffness adjustment based on the swing state parameters is as follows: Calculate the current natural frequency of the suspended load. : in, It is the acceleration due to gravity. This is the original length of the cable. This is the static elongation of the cable. For the suspended load mass, This is the equivalent elastic coefficient of the current cable; Calculate the real-time dominant oscillation frequency : in, To prevent division by zero minimum constant; Calculate the frequency offset potential function Quantify the energy distance between the current oscillation state and the resonance state: in, For frequency difference, This is the stiffness adjustment gain coefficient. The preset minimum safe frequency difference threshold, Used as the reference swing angle constant; Based on the frequency offset potential function Calculate the required cable target stiffness adjustment for the negative gradient direction of stiffness. This causes the system to move away from the resonant state along the direction in which the potential function decreases most rapidly at the stated frequency; whereby... The expression is as follows: 。 4. The method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport according to claim 3, characterized in that, The specific method for generating the power-on control command in step S3 is as follows: Based on the electrostatic actuation characteristics of electrodeformable materials, the required energizing voltage is established. With target stiffness adjustment amount Mapping relationship between them: in, The initial wall thickness of the electro-deformable joint is given. The Young's modulus of the material. The vacuum permittivity, The relative permittivity, The effective area of ​​the electrode. A geometric factor characterizing the deformation transfer efficiency of a cable braided structure; like When the value is positive, the controller outputs the voltage. To increase stiffness by causing the electro-deformable joint to contract; like When the value is negative, the controller outputs a preset bias voltage to put the electro-deformable joint in a semi-activated state to reduce its stiffness.

5. The method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport according to claim 4, characterized in that, When the cable body contains When generating an axially distributed electrodeformable section, the method for generating an energizing control command further includes: Adjustment based on the current target stiffness Calculate the number of electrodeformable nodes to be activated : in, This represents the standard stiffness increment produced by a single electrocaustic joint under rated voltage. Indicates rounding up; Starting with the first section closest to the drone platform, proceed sequentially towards the next... The voltage is applied to each electro-deformable section. This is to generate a continuous stiffness gradient distribution.

6. The method for suppressing vibration during unmanned aerial vehicle (UAV) sling transport according to claim 4, characterized in that, During the execution of the power-on control command, the frequency offset potential function is continuously calculated. The gradient, when detected and hour If it is determined that the suspended load has left the resonance sensitive area, a power-off command is executed to restore the initial size of the electro-deformable joint; Where ξ is the preset gradient convergence threshold, The preset security threshold is defined as follows.

7. A drone-borne transport system, characterized in that, include: Unmanned aerial vehicle (UAV) platform; A variable stiffness cable, one end of which is connected to the UAV platform; the variable stiffness cable includes a cable body and at least one electro-deformable joint wound into the cable body; The mounting mechanism, connected to the other end of the variable stiffness cable, is used to connect and suspend the load; A visual monitoring unit is installed near the mounting mechanism to collect image data of the swing state of the suspended load. A controller, mounted on the UAV platform, is electrically connected to the visual monitoring unit and the electro-deformation energy-saving device; the controller is configured to perform the vibration suppression method according to any one of claims 1 to 6.

8. The UAV sling transport system according to claim 7, characterized in that, The electro-deformable joint comprises, from the inside out: a safety load-bearing core, an electro-deformable sleeve, a flexible conductive outer layer, and an outer insulating sheath; both ends of the electro-deformable joint are fixedly connected to the cable body through mechanical connectors, and the flexible conductive outer layer is electrically connected to the controller through wires.

9. The UAV sling transport system according to claim 8, characterized in that, The electrodeformable sleeve is made of a copolymer dielectric elastomer, which contracts axially when the controller applies a voltage and returns to its original length when the voltage is cut off.

10. The UAV sling transport system according to claim 7, characterized in that, The controller controls the energization and contraction of different numbers of electro-deformable joints based on the swing amplitude of the suspended load.

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