Plant protection unmanned aerial vehicle liquid medicine shaking prevention plant protection machine medicine box

Abstract

This invention belongs to the field of unmanned aerial vehicle (UAV) technology, specifically a pesticide tank for preventing pesticide spraying from shaking in agricultural drones. It includes: a main tank body suspended from the UAV body to hold the pesticide spraying, with a sealed air chamber pre-installed above the liquid surface inside the tank body; a sensing and acquisition module for real-time acquisition of flight motion parameters of the UAV body and pesticide spraying state parameters within the tank body; and a main control unit communicatively connected to the sensing and acquisition module, configured to obtain the air cushion pressure above the target liquid surface through multiphysics field coupling calculation based on the acquired flight motion parameters and pesticide spraying state parameters. By offsetting and suppressing the irregular transfer of large-mass fluid, this invention effectively solves the problem of severe shaking of the pesticide spraying due to alternating inertial forces during frequent high-maneuvering maneuvers such as start-up acceleration, sudden stop hovering, and sharp-angle turns, which leads to high-frequency random shifts in the aircraft's center of gravity and abnormal attitude oscillations.

Description

Technical Field

[0001] This invention belongs to the field of drone technology, specifically a pesticide tank for agricultural drones that prevents pesticide liquid from shaking. Background Technology

[0002] In recent years, with the rapid development of precision agriculture, plant protection drones have been widely used in agricultural plant protection operations such as pesticide spraying and liquid fertilizer application due to their significant advantages such as high efficiency, maneuverability, and strong terrain adaptability.

[0003] However, in actual high-efficiency operation scenarios, agricultural drones need to frequently perform highly maneuverable actions such as starting acceleration, sudden stop hovering, large-angle turns, and rapid terrain-following flight in complex terrain. Under these drastic changes in external flight trajectory acceleration and attitude angular velocity, the liquid pesticide inside the tank will inevitably be subjected to the violent impact of complex alternating inertial forces, which directly leads to the irregular transfer of large mass fluid in the enclosed space, and thus causes the overall center of gravity of the drone to shift randomly and frequently.

[0004] This unknown, time-varying center of gravity shift, which is severely coupled with flight maneuvers, can completely destroy the dynamic stability of the aircraft. Under mild conditions, the random shift of the center of gravity can cause abnormal oscillations in the UAV's flight attitude, forcing the flight control system to frequently schedule each rotor motor for extreme compensation. This not only significantly increases the system's energy dissipation and severely shortens the operational range, but also causes deviations in the spraying route and uneven distribution of atomized liquid. Under extreme conditions, the violent liquid impact and the instantaneous large shift of the center of gravity can easily break through the physical envelope of the UAV's attitude control, directly inducing serious production safety accidents such as aircraft stall, overturning, or even crashing.

[0005] Therefore, the present invention provides a pesticide tank for agricultural drones to prevent pesticide spraying from shaking. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by this invention to solve its technical problem is: a pesticide tank for preventing pesticide spraying from shaking in agricultural drones, comprising: The main body of the medicine box is suspended on the main body of the drone and is used to carry the liquid medicine. A sealed air chamber is reserved above the liquid surface inside the main body of the medicine box. The perception and acquisition module is used to acquire the flight motion parameters of the main body of the drone and the state parameters of the liquid medicine in the main body of the medicine tank in real time. The main control unit is communicatively connected to the sensing and acquisition module and is configured to obtain the air cushion pressure above the target liquid surface through multi-physics field coupling calculation based on the acquired flight motion parameters and the liquid state parameters. The air pressure regulating actuator is controlled and connected to the main control unit and connected to the air chamber of the main body of the medicine tank. It is used to dynamically adjust the absolute air pressure in the air chamber according to the air cushion pressure above the target liquid surface, so as to suppress the violent shaking of the liquid surface by compressing the upper air cushion rigidity.

[0008] The beneficial effects of this invention are as follows: 1. The present invention relates to a pesticide tank for preventing pesticide sloshing in agricultural drones. Based on real-time flight motion and pesticide state parameters acquired by the main control unit, the pressure of the air cushion above the target liquid surface is calculated through multi-physics field coupling. The absolute pressure inside the air chamber is dynamically adjusted using an air pressure regulating mechanism. The upper air cushion's stiffness generates a downward compressive force, directly offsetting and suppressing the irregular transfer of large-mass fluid. This effectively solves the problem of severe sloshing of the pesticide due to alternating inertial forces when the drone frequently performs high-maneuverability maneuvers such as start-up acceleration, sudden stops, hovering, and sharp turns, leading to high-frequency random shifts in the aircraft's center of gravity and abnormal attitude oscillations.

[0009] 2. The pesticide tank for preventing pesticide sloshing in agricultural drones, as described in this invention, achieves precise quantification of the microscopic physical properties of the fluid and boundary layer effects within a closed space by setting up a liquid sloshing dissipation calculation module, a wall slip resistance calculation module, and a sloshing frequency-excitation sensitive calculation module within the anti-sloshing robust control subsystem. At the same time, it combines the inner wall surface roughness and static contact angle to evaluate the wall slip resistance, and uses the Lorentz peak model to keenly capture the critical resonance risk of the system, so that the system can exhibit adaptive suppression capability when facing different pesticide media and geometric filling states.

[0010] 3. The pesticide tank for preventing pesticide sloshing in agricultural drones, as described in this invention, utilizes an arctangent mapping function to unify the liquid dissipation number, excitation sensitivity index, drone body angular velocity limit, and flight trajectory jerk into a dimensionless cooperative robustness index. This ensures the smoothness and convergence of calculation results under extreme flight conditions. Furthermore, an air cushion pressure optimization model with a logarithmic compensation structure is introduced. When a critical state of rapidly decreasing machine-liquid robustness and weakened wall resistance is detected, logarithmic-level high-pressure compensation feedback can be quickly generated. This strategy achieves precise application and smooth transition of pesticide suppression force, perfectly resolving the deep coupling contradiction between high-maneuverability flight control and complex liquid sloshing. Attached Figure Description

[0011] The invention will now be further described with reference to the accompanying drawings.

[0012] Figure 1 This is a perspective view of the present invention; Figure 2 This is a system flowchart of the present invention; Figure 3 This is a flowchart of the recursive solution process of the five modules of the anti-sway robust control subsystem in this invention; Figure 4 This is a flowchart of the logarithmic structure nonlinear boosting compensation mechanism in this invention.

[0013] In the picture: 1. The main body of the drone; 2. The main body of the medicine box. Detailed Implementation

[0014] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0015] The pesticide tank for preventing pesticide spraying from shaking in agricultural drones, as described in this embodiment of the invention, includes: The main body 2 of the medicine box is suspended on the main body 1 of the drone and is used to carry the liquid medicine. A sealed air chamber is reserved above the liquid surface inside the main body 2 of the medicine box. The air chamber is a space reserved above the liquid surface inside the main body 2 of the medicine box that is relatively isolated from the outside. The air chamber is used to contain gas and apply force to the liquid surface of the medicine by adjusting its internal air pressure, thereby suppressing the shaking of the liquid medicine.

[0016] The perception and acquisition module is used to acquire the flight motion parameters of the main body 1 of the drone and the state parameters of the liquid medicine in the main body 2 of the medicine tank in real time. Flight motion parameters refer to physical quantities that describe the current flight state of the UAV body 1, such as the attitude angles (pitch angle, roll angle, yaw angle), angular velocity, linear acceleration, and flight trajectory jerk of the UAV body 1.

[0017] Medicine liquid state parameters refer to quantities that describe the current physical state of the medicine liquid inside the medicine tank, such as the liquid level, temperature, density, viscosity, and surface tension.

[0018] The main control unit, which communicates with the sensing and acquisition module, is configured to obtain the air cushion pressure above the target liquid surface through multiphysics coupling calculation based on the acquired flight motion parameters and liquid state parameters. Air cushion pressure above the target liquid surface This refers to the ideal air pressure value calculated by the main control unit for effectively suppressing the sloshing of the drug solution. This pressure value is dynamically changing and is designed to provide the best suppression effect based on real-time operating conditions. The air pressure regulating actuator is connected to the main control unit and to the air chamber of the main body 2 of the medicine tank. It is used to regulate the air pressure based on the air cushion pressure above the target liquid surface. The absolute air pressure in the air chamber is dynamically adjusted to suppress violent shaking of the liquid surface by compressing it with the rigidity of the upper air cushion. The air pressure adjustment actuator usually includes components such as an air pump, valves and pressure sensors to achieve dynamic control of the air chamber pressure.

[0019] The perception and acquisition module is configured to acquire the flight motion parameters of the main body 1 of the UAV and the liquid status parameters of the medicine tank 2 in real time. The flight motion parameters can be acquired through the flight control system interface of the main body 1 of the UAV, such as by reading the attitude angle, angular velocity and acceleration data output by the flight controller.

[0020] The liquid status parameters can be obtained by sensors installed inside the medicine tank. For example, by installing multiple resistive liquid level sensors on the side wall of the medicine tank, the current liquid level can be roughly determined in a step-like manner.

[0021] Based on this, the main control unit communicates with the sensing and acquisition module and is configured to obtain the air cushion pressure above the target liquid surface through multiphysics coupling calculation based on the acquired flight motion parameters and liquid state parameters. The main control unit can be an embedded microcontroller that stores a pre-calibrated lookup table. This lookup table directly outputs the corresponding target air cushion pressure based on different combinations of flight motion parameters and liquid state parameters. For example, when the main body of the drone 1 makes a sharp turn, the main control unit looks up a preset higher air cushion pressure value from a lookup table based on the current attitude angle and liquid level. In another implementation, the main control unit can be a digital signal processor that runs a simplified empirical formula model. This model takes flight motion parameters and liquid state parameters as input and calculates an approximate target air cushion pressure through linear or nonlinear functional relationships. These methods can all generate a target pressure value based on the input data.

[0022] Therefore, the air pressure regulating actuator is connected to the main control unit and to the air chamber of the medicine tank body 2, used to regulate the air pressure based on the air cushion pressure above the target liquid surface. The absolute air pressure in the air chamber can be dynamically adjusted. The upper air cushion can be used to compress and suppress the violent shaking of the liquid surface. The air pressure adjustment actuator can include a bidirectional micro air pump and an automatic pressure relief valve. When the main control unit calculates that pressurization is required, the air pump is started to fill the air chamber. When pressure relief is required, the main control unit controls the air pump to reverse and pump air or open the automatic pressure relief valve.

[0023] When the main body of the drone 1 suddenly climbs, causing its pitch angle and vertical acceleration to increase rapidly, the liquid inside the medicine tank 2 will tend to impact the rear wall of the medicine tank due to inertia, resulting in violent shaking.

[0024] At this moment, the multi-axis inertial measurement unit will immediately detect the sharp changes in the pitch angle and vertical acceleration of the UAV body 1. At the same time, the non-contact level gauge installed inside the medicine tank body 2 will monitor the changes in the liquid level of the medicine and the surface fluctuations caused by the sloshing of the medicine in real time, thereby obtaining the state parameters of the medicine and transmitting them to the main control unit.

[0025] Next, after receiving these flight motion parameters and liquid state parameters, the main control unit will immediately start its internal multiphysics coupling calculation program. This program comprehensively considers various factors such as the current flight attitude and acceleration of the UAV body 1, the current liquid level, density, and viscosity of the liquid, and calculates the optimal air cushion pressure above the target liquid surface required to suppress liquid sloshing under the current operating conditions through complex fluid dynamics and gas dynamics models. For example, in a scenario where a rapid ascent causes the liquid to shift backward, the main control unit will calculate a relatively high value. The value is adjusted to create a stronger pressure above the surface of the liquid.

[0026] Subsequently, the main control unit will calculate the air cushion pressure above the target liquid surface. The value is sent to the pressure regulating actuator, which, for example, its bidirectional micro air pump, will rapidly inflate or deflate the sealed air chamber inside the main body 2 of the medicine box according to the instructions of the main control unit, so as to dynamically regulate the absolute air pressure in the air chamber to achieve the desired pressure. .

[0027] As a result, the air pressure inside the air chamber increases, and the upper air cushion stiffness applies a downward pressure to the liquid surface. This pressure can effectively counteract or suppress the violent shaking of the liquid caused by inertia, stabilizing the liquid surface in a relatively stable state. In this way, the offset of the liquid's center of gravity is greatly reduced, thereby maintaining the flight attitude stability of the UAV body 1 when performing high-maneuver maneuvers.

[0028] Compared with the traditional method of using fixed baffles or compartments to suppress liquid sloshing in existing medicine boxes, this application can adaptively adjust according to the real-time intensity and direction of liquid sloshing, effectively solving the problem of center of gravity shift caused by liquid sloshing in the UAV body 1 during high-maneuverability flight missions, thereby avoiding a series of negative impacts such as flight attitude instability, increased energy dissipation, and reduced operational safety.

[0029] The main control unit is equipped with an anti-sloshing robust control subsystem, which includes, in sequence: a liquid sloshing dissipation calculation module, a wall slip resistance calculation module, a sloshing frequency-excitation sensitivity calculation module, a machine-liquid co-operation robustness calculation module, and an air cushion pressure optimization output module.

[0030] The anti-sway robust control subsystem is an integrated software or hardware module whose main function is to provide a robust control method for multi-physics coupling. This subsystem can be used as firmware or application within the main control unit and can run on processors such as microcontrollers, digital signal processors (DSPs) or field-programmable gate arrays (FPGAs).

[0031] The liquid sloshing dissipation calculation module is used to quantify the energy dissipation capacity of the liquid itself. It is used to evaluate the degree to which the liquid dissipates energy through internal friction and viscosity during sloshing, providing a fluid dynamics benchmark for subsequent air cushion pressure adjustment. The mathematical formula of the liquid sloshing dissipation model can be implemented by programming, and physical parameters such as the zero-shear viscosity, surface tension, and density of the liquid can be input for real-time calculation. Alternatively, for a specific liquid, the dissipation number under different parameter combinations can be pre-calculated and stored as a lookup table for direct querying during runtime to improve calculation efficiency.

[0032] The wall slip resistance calculation module is used to evaluate the impact of the interaction between the liquid and the inner wall of the tank body 2 on the sway resistance. It is used to correct the motion state of the fluid at the boundary of the tank body 2 wall and ensure accurate modeling of the boundary layer effect. This module can realize the mathematical formula of the wall slip resistance model through programming. It can calculate by inputting parameters such as the surface roughness of the inner wall of the tank, the static contact angle between the liquid and the tank wall, and the preset pitch or roll angular velocity limit of the UAV body 1.

[0033] The frequency sloshing-excitation sensitivity calculation module is a calculation module used to identify the sensitivity of the drug liquid sloshing frequency to external excitation. It is used to evaluate the sensitivity of the system to the sloshing frequency under the current liquid level and the geometry of the main body 2 of the drug tank, thereby providing a basis for suppressing resonance. This module can implement the mathematical formula of the frequency sloshing-excitation sensitivity model by programming, and calculate it by inputting parameters such as the system's equivalent damping ratio, filling ratio and the slenderness ratio of the drug tank.

[0034] The machine-liquid co-robustness calculation module is a calculation module used to quantitatively evaluate the dynamic coupling relationship between flight maneuvers and liquid sloshing. It is used to comprehensively consider factors such as liquid sloshing dissipation, wall slip resistance, sloshing frequency-excitation sensitivity, and the acceleration of the UAV body's flight trajectory to evaluate the stability of the entire machine-liquid system. The mathematical formula of the machine-liquid co-robustness model can be implemented by programming, and the calculation can be performed by inputting the calculation results of each of the aforementioned modules and flight parameters.

[0035] The air cushion pressure optimization output module acts as the decision layer, integrating the calculation results from various modules to output the air cushion pressure above the target liquid surface. The calculation module is used to realize adaptive optimization control based on multi-physics coupling state and dynamically adjust the absolute air pressure in the air chamber. This module can realize the mathematical formula of the air cushion pressure optimization model through programming. The preset initial air cushion pressure above the liquid surface, the maximum allowable pressurization of the medicine box, the calculated machine-liquid cooperative robustness, and the wall slip resistance coefficient are input for calculation.

[0036] After receiving the data, the main control unit first performs its respective physical parameter calculations in parallel or serially using the liquid sloshing dissipation calculation module, the wall slip hindrance calculation module, and the sloshing frequency-excitation sensitivity calculation module. Then, the machine-liquid co-operation robustness calculation module couples these calculation results with the real-time flight trajectory jerk to calculate the machine-liquid co-operation robustness. Finally, the air cushion pressure optimization output module integrates all the calculation results to calculate the air cushion pressure above the target liquid surface. ,Should The value is then sent to the pressure regulating actuator, which drives the bidirectional micro air pump to perform corresponding pressurization or depressurization actions to achieve dynamic regulation of the absolute air pressure in the air chamber.

[0037] The above technical solution overcomes the limitations of traditional solutions that rely solely on basic pressure regulation to address nonlinear sloshing characteristics under multi-physics coupling. By constructing a hierarchical and progressive anti-sloshing robust control subsystem, the liquid sloshing problem is deconstructed into multiple interconnected physical calculation modules. This allows the main control unit to more comprehensively and accurately understand the intrinsic mechanism and external excitation response of the liquid sloshing, thereby outputting a more precise air cushion pressure above the target liquid surface. This adaptive optimization control significantly improves the system's anti-interference capability and robustness under complex maneuvering conditions, effectively suppresses violent shaking of the liquid surface, and avoids problems such as abnormal flight attitude oscillation, increased energy dissipation, shortened operating range, deviation of spraying route, and aircraft stall, overturning, or even crashing in extreme cases caused by center of gravity shift.

[0038] The liquid sloshing dissipation solution module constructs a liquid sloshing dissipation model with a rational fractional structure to obtain the dimensionless liquid sloshing dissipation number. The liquid sloshing dissipation number is configured to characterize the proportional relationship between the viscous friction and surface tension dissipation mechanism inside the fluid. Its calculation logic is as follows: the square of the zero-shear viscosity of the liquid is used as the numerator, and the sum of the square of the zero-shear viscosity of the liquid and the gravity-surface tension coupled dissipation term is used as the denominator. Among them, the gravity-surface tension coupled dissipation term is positively correlated with the Bond number, liquid density, liquid surface tension, and characteristic length of the medicine box.

[0039] The liquid sloshing dissipation calculation module quantifies the inherent energy dissipation capacity of the liquid when it sloshes inside the main body 2 of the medicine tank. This module can be an independent software program segment that runs on the processor of the main control unit and is responsible for performing specific calculation tasks.

[0040] The formula for the liquid sloshing dissipation model is:

[0041] Zero-shear viscosity of the drug solution Viscosity refers to the viscosity of a drug solution at extremely low shear rates. It reflects the internal friction of the drug solution in a static or slow-flowing state and is an important parameter for the dissipation of energy inside the drug solution. Its value can be measured in advance in the laboratory for different drug solutions and stored in the memory of the main control unit, or it can be measured in real time by an online microrheological sensor.

[0042] Surface tension of drug solution The unit is Surface tension is a contractile force caused by intermolecular forces on the liquid surface. It affects the stability and sloshing pattern of the liquid surface. Its value can be determined and stored in advance or measured in real time by a surface tension sensor.

[0043] drug solution density It refers to the mass of the liquid medicine per unit volume, a fundamental parameter for fluid dynamics calculations, which can be determined in advance or measured in real time using a density sensor. The characteristic length of the medicine tank is also relevant. These are characteristic parameters that characterize the geometric dimensions of the medicine box body 2. For example, the equivalent diameter, maximum width, or length of the medicine box body 2 can be taken. Their values ​​can be preset and stored according to the design parameters of the medicine box body 2.

[0044] Bond Number It is a dimensionless number used to represent the ratio of gravity to surface tension. In liquid sloshing, it determines the liquid surface morphology and sloshing pattern. Its calculation is performed by the main control unit according to its defined formula. It was calculated using known drug liquid density, gravitational acceleration, characteristic length of the medicine box, and surface tension of the drug liquid.

[0045] The rational fractional liquid sloshing dissipation model is a mathematical model whose structure is the ratio of two polynomials. It is used to describe the relationship between the liquid sloshing dissipation number and the above physical parameters. This model can be integrated as a software algorithm into the liquid sloshing dissipation solution module. It can be calculated by inputting parameters, or the dissipation number under different parameter combinations can be pre-calculated by using a lookup table (LUT) to improve real-time performance.

[0046] Dimensionless liquid sloshing dissipation number It is a value between 0 and 1, used to quantify the energy dissipation capability of liquid sloshing. The larger the value, the stronger the inherent dissipation capability of the liquid and the faster the sloshing energy decays. Its value is calculated by the liquid sloshing dissipation solution module based on the liquid sloshing dissipation model with rational fraction structure.

[0047] The flight motion parameters of the drone body 1 and the state parameters of the liquid medicine inside the medicine tank body 2 are acquired in real time through the sensing and acquisition module. The state parameters of the liquid medicine include the zero shear viscosity of the liquid medicine. Surface tension of the drug solution Drug solution density Key physical properties, these parameters, along with the characteristic length of the medicine box The data is input into the liquid sloshing dissipation calculation module, which first calculates the liquid density. Gravitational acceleration Medicine box characteristic length and the surface tension of the drug solution Calculate the Bond number Then, all relevant parameters are substituted into the pre-defined rational fractional liquid sloshing dissipation model to calculate the dimensionless liquid sloshing dissipation number. .

[0048] this The value accurately characterizes the inherent damping properties of the current liquid under a specific medicine tank geometry, that is, the ability of the liquid itself to suppress sloshing energy. By obtaining this key parameter, the main control unit subsequently obtains the air cushion pressure above the target liquid surface through multiphysics coupling calculation. In this system, the inherent dissipation mechanism of the propellant is fully considered, rather than solely relying on external air pressure regulation. This allows the air pressure regulation actuator to formulate more precise and targeted control strategies when dynamically adjusting the absolute air pressure within the chamber. This avoids over- or under-regulation caused by ignoring the inherent properties of the propellant, thus more effectively suppressing violent sloshing of the propellant surface through the stiffness of the upper air cushion. This quantification of the intrinsic dissipation mechanism, combined with the synergistic effect of external air pressure regulation, significantly enhances the adaptability and robustness of the entire propellant tank system to different propellant media and various flight conditions.

[0049] Through the above technical solution, this application introduces a liquid sloshing dissipation calculation module, and constructs a rational fractional liquid sloshing dissipation model based on the zero-shear viscosity of the liquid, the surface tension of the liquid, the density of the liquid, the characteristic length of the medicine tank, and the Bond number. This model can accurately quantify the inherent damping characteristics of the liquid itself, enabling the main control unit to fully consider the influence of the physical properties of the liquid and the geometry of the medicine tank on the sloshing energy attenuation when making air pressure regulation decisions. This avoids the problems of inaccurate and untargeted regulation strategies caused by ignoring the inherent dissipation mechanism of the liquid in traditional solutions. Furthermore, by converting the inherent dissipation capacity of the liquid into a dimensionless liquid sloshing dissipation number, a more comprehensive and accurate input is provided for subsequent air cushion pressure optimization. This significantly improves the suppression effect of the air pressure regulation actuator on liquid sloshing under different liquid media and different filling states, and enhances the flight stability of the entire UAV body 1.

[0050] The wall slip resistance solution module constructs a wall slip resistance model with a trigonometric function coupling structure to obtain the dimensionless wall slip resistance coefficient; The wall slip resistance coefficient is obtained by multiplying the roughness resistance factor and the contact angle wetting factor; wherein, the roughness resistance factor is configured as the square of the sine function of the dimensionless inner wall surface roughness term, and the dimensionless inner wall surface roughness term is determined by the surface roughness of the inner wall of the box and the thickness of the fluid viscous sublayer; the contact angle wetting factor is configured as the square of the cosine function of half of the static contact angle between the liquid and the box wall.

[0051] Among them, the wall slip resistance calculation module is a calculation unit specifically used to calculate the motion damping of the liquid medicine on the inner wall of the medicine tank. This module can be integrated as a software algorithm into the processor of the main control unit, such as program code running on an embedded microcontroller or digital signal processor.

[0052] Surface roughness of the inner wall of the box This refers to the degree of microscopic unevenness of the inner wall surface of the medicine box. This parameter can be obtained in various ways, such as by measuring it during the medicine box manufacturing process using a surface roughness measuring instrument (such as a stylus roughness meter or an optical roughness meter) and storing it as a system parameter; or, it can be preset with a typical value based on the material and manufacturing process of the medicine box.

[0053] Static contact angle between liquid medicine and tank wall This describes the wetting properties of the liquid medicine on the inner wall of the medicine box. This parameter can be determined experimentally, such as by using a contact angle meter to measure the combination of a specific liquid medicine and the medicine box material; or it can be set by consulting relevant databases or empirical values ​​based on the chemical properties of the liquid medicine and the material characteristics of the medicine box.

[0054] Preset pitch or roll rate limit for the main body of the drone 1 This refers to the preset value of the maximum angular velocity that the main body of the drone 1 can reach on its pitch axis or roll axis during flight. This limit value can be configured by the manufacturer in the flight control system as part of the flight performance envelope; or it can be set by the user or system administrator according to the design capability of the actual needs of plant protection operations.

[0055] The wall slip retardation model of the triangular coupling structure is a mathematical expression that couples the above parameters such as roughness, contact angle, and fluid viscous sublayer thickness through trigonometric function relationships to quantify the wall slip retardation effect. This model can be used as part of the algorithm and calculated in the wall slip retardation solution module.

[0056] The formula for the wall slip resistance model is:

[0057] Among them, the zero shear viscosity of the drug solution The dimensions are drug solution density The dimensions are Angular velocity limiting The dimensions are Through formula derivation, the thickness of the fluid viscous sublayer is obtained. Possessing international standard length dimensions .

[0058] Dimensionless wall slip resistance coefficient This is the output of the model, with a value ranging from 0 to 1. It is used to characterize the degree to which the wall inhibits the sloshing of the liquid medicine. This coefficient can be directly used as the input parameter for the subsequent air cushion pressure optimization output module.

[0059] in, The thickness of the viscous sublayer is given, and the thickness of the viscous sublayer is given. With zero shear viscosity of the drug solution Drug solution density And the pitch or roll rate limit of the main body of the drone. Relationship satisfaction .

[0060] Fluid viscosity sublayer thickness This refers to a thin layer with a large velocity gradient formed by the liquid medicine near the inner wall of the medicine tank due to viscosity. This thickness is dynamically calculated, and the calculation requires the zero-shear viscosity of the liquid medicine. and drug solution density The parameters can be obtained through the physical properties of the liquid medicine, such as by real-time measurement using sensors or by reading from a pre-set liquid medicine database.

[0061] By introducing a wall slippage hindrance calculation module, the energy dissipation of the liquid medicine during sloshing inside the medicine tank can be assessed more precisely in the anti-sloshing robust control subsystem of the main control unit. Specifically, this module receives the surface roughness of the inner wall of the tank. Static contact angle between the liquid medicine and the tank wall And the preset pitch or roll rate limit of the drone body 1 As input, surface roughness This directly reflects the physical resistance of the wall's microstructure to the flow of the liquid medicine; the greater the roughness, the greater the sliding resistance of the liquid medicine on the wall. static contact angle This characterizes the wetting properties of the drug solution on the wall surface, affecting the adhesion between the drug solution and the wall surface, and thus influencing the slip behavior. Additionally, this module also considers the zero-shear viscosity of the drug solution. Drug solution density And the pitch or roll rate limit of the main body of the drone. Dynamic calculation of fluid viscous sublayer thickness .

[0062] This thickness correlates the macroscopic flight maneuver intensity with the microscopic hydrodynamic boundary layer thickness, allowing the wall slip drag coefficient to adaptively adjust with changes in flight state. Subsequently, these parameters are input into a wall slip drag model with a triangular coupling structure, and after calculation, a dimensionless wall slip drag coefficient is output. .

[0063] This coefficient comprehensively reflects the energy dissipation capacity of the liquid at the tank wall, providing the main control unit with more accurate information about the liquid sloshing damping. By incorporating this coefficient into the subsequent air cushion pressure optimization calculation, the main control unit can more accurately adjust the absolute air pressure in the air chamber, thereby more effectively suppressing the violent sloshing of the liquid surface. It can adaptively adjust according to the actual interaction characteristics between the liquid and the inner wall of the tank, rather than relying solely on macroscopic flight motion parameters, significantly improving the accuracy of liquid sloshing suppression.

[0064] The above technical solution allows for a more accurate assessment of energy dissipation when the liquid medicine sloshes inside the tank, overcoming the inaccurate assessment problem caused by neglecting the sliding and dragging characteristics between the liquid medicine and the tank wall in traditional methods. This suppresses violent sloshing of the liquid medicine surface and reduces the adverse effects of center of gravity shift caused by liquid medicine sloshing on flight performance when the UAV body 1 performs high-maneuverability maneuvers such as start-up acceleration, sudden stop hovering, sharp-angle turns, and rapid terrain-following flight in complex terrain.

[0065] The frequency-scratching sensitivity solution module constructs a frequency-scratching sensitivity model with Lorentz resonance peak characteristics to obtain a dimensionless frequency-scratching sensitivity index. The calculation logic of the frequency-excitation sensitivity index is as follows: extract the square of the equivalent damping ratio of the system as the reference numerator, and the denominator is formed by adding the reference numerator and a deviation penalty term; the deviation penalty term represents the absolute degree of deviation of the current filling ratio from the critical resonance filling ratio of the system, and the critical resonance filling ratio is independently determined by the slenderness ratio of the tank to ensure that when the filling ratio approaches the critical resonance region, the frequency-excitation sensitivity index produces a nonlinear surge.

[0066] Frequency swaying-excitation sensitive solution module is based on the system equivalent damping ratio Filling ratio and the length-to-slenderness ratio of the medicine box A Lorentz peak-shaped fluctuation frequency-excitation sensitivity model was constructed to obtain the dimensionless fluctuation frequency-excitation sensitivity index. Frequency fluctuation-excitation sensitivity index The output range is 0 to 1, and the formula for the frequency flicker-excitation sensitive model is:

[0067] The frequency sloshing-excitation sensitive calculation module is a key component of the anti-sloshing robust control subsystem inside the main control unit. Its main function is to quantify the matching degree between the liquid sloshing frequency inside the medicine tank and the external flight excitation frequency. It can be implemented as a software subroutine inside the main control unit, an independent digital signal processor (DSP) module, or through hardware acceleration calculation via a field-programmable gate array (FPGA).

[0068] System equivalent damping ratio This characterizes the energy dissipation capability of the liquid sloshing system inside the medicine tank, reflecting the system's inherent vibration suppression characteristics. The liquid sloshing dissipation number is calculated by the liquid sloshing dissipation solution module. Obtained indirectly, for example, through a pre-defined mathematical formula. Perform the calculation.

[0069] Filling ratio Defined as the current liquid level height in the medicine tank. Total height of the medicine box The ratio, i.e. It directly reflects the liquid filling status of the medicine tank and is an important geometric parameter affecting the liquid sloshing characteristics. The current liquid level height can be measured in real time using a non-contact level gauge. And combined with the known total height of the medicine box Perform the calculation.

[0070] Medicine box length-to-slenderness ratio Defined as the total internal height of the medicine box Equivalent diameter of the bottom of the medicine box The ratio, i.e. It describes the geometric features of the medicine box and has a significant impact on the natural frequency and pattern of liquid sloshing. The length-to-slenderness ratio of the medicine box is a preset geometric parameter that can be determined during the medicine box design stage.

[0071] The Lorentz peak structure is a common mathematical model structure, usually used to describe resonance phenomena or response curves with specific peaks. Here, it is used to construct a sloshing frequency-excitation sensitivity model, which can effectively capture the characteristic that the system sensitivity increases sharply when the liquid sloshing frequency is close to the external excitation frequency, thereby quantifying the resonance risk.

[0072] The frequency flicker-excitation sensitivity model is used to calculate the frequency flicker-excitation sensitivity index. The core of the mathematical expression for it lies in the equivalent damping ratio of the system. Filling ratio Compared to the length and slenderness of the medicine box By organically combining key parameters, the sensitivity of the liquid sloshing inside the medicine tank to external flight stimuli can be quantified, resulting in a dimensionless sloshing frequency-stimuli sensitivity index. It is a dimensionless value between 0 and 1, used to intuitively represent the sensitivity of the liquid sloshing system to external flight stimuli under the current liquid filling state and geometry of the medicine tank. The higher the value, the more susceptible the system is to external stimuli and the more likely it is to experience violent shaking, i.e., the greater the risk of resonance.

[0073] By introducing a frequency-excitation sensitivity calculation module and constructing a Lorentz peak-shaped frequency-excitation sensitivity model based on the system's equivalent damping ratio, filling ratio, and tank slenderness ratio, the dimensionless frequency-excitation sensitivity index can be obtained dynamically and quantitatively. This intuitively reflects the sensitivity of the liquid sloshing system to external flight stimuli under the current liquid state and tank geometry, especially identifying conditions with a high risk of resonance. This allows the main control unit to more accurately assess the potential risks of liquid sloshing, providing a refined basis for subsequent air cushion pressure adjustment. Therefore, when the UAV body 1 performs high-maneuvering maneuvers, the air pressure adjustment actuator can dynamically adjust the absolute air pressure in the air chamber more specifically based on the real-time calculated sensitivity index, effectively suppressing violent sloshing of the liquid surface and avoiding stability problems caused by resonance between the sloshing frequency and the excitation frequency. This significantly improves the attitude stability, operational accuracy, and flight safety of the UAV body 1 under complex flight conditions.

[0074] The machine-liquid synergy robustness calculation module constructs a machine-liquid synergy robustness model based on the arctangent function to obtain dimensionless machine-liquid synergy robustness; The machine-liquid co-robustness model obtains the machine-liquid co-robustness by constructing a comprehensive independent variable and mapping it with arctangent normalization. The comprehensive independent variable is the product of the state stability term and the motion shock term. The state stability term is configured as a fraction, the numerator of which is composed of the liquid sloshing dissipation number and the square of (1 minus sloshing frequency - excitation sensitivity index), and the denominator is preset to a constant 2. The motion shock term is configured as the ratio of the limit angular velocity characteristic parameter of the UAV body 1 to the current actual flight trajectory jerk, and a preset dynamic calculation bias constant is introduced into the denominator of the ratio characteristic term to prevent calculation divergence.

[0075] The machine-liquid co-robustness calculation module is based on the liquid sloshing dissipation number. Frequency fluctuation - excitation sensitivity index Limiting the pitch or roll rate of the UAV body 1 Characteristic response time And the flight trajectory accelerometer collected in real time by the sensing acquisition module. A machine-fluid cooperative robustness model with an arctangent mapping structure is constructed to obtain dimensionless machine-fluid cooperative robustness. Mechanical-hydraulic synergistic robustness The output range is 0 to 1, and the formula for the machine-fluid synergistic robustness model is:

[0076] Among them, the machine-liquid cooperative robustness calculation module is a functional module used to evaluate the cooperative stability between the UAV body 1 and the liquid sloshing. This module can be implemented as a software subroutine inside the main control unit, or it can be hardware accelerated by a dedicated digital signal processor (DSP) or field programmable gate array (FPGA) to meet real-time requirements.

[0077] Liquid sloshing dissipation It characterizes the energy dissipation capacity of the liquid medicine when it shakes inside the main body 2 of the medicine box due to factors such as viscosity and surface tension. It is a dimensionless quantity ranging from 0 to 1. The larger the value, the stronger the dissipation capacity and the easier it is to suppress the shaking of the liquid medicine.

[0078] Frequency fluctuation - excitation sensitivity index It characterizes the sensitivity between the frequency of drug liquid sloshing and the frequency of external excitation. It is a dimensionless quantity ranging from 0 to 1. The larger the value, the more sensitive the drug liquid sloshing is to external excitation and the easier it is to be excited to slosh violently.

[0079] Limiting the pitch or roll angular velocity of the drone body 1 This is the preset maximum permissible angular velocity of the UAV body 1 in the pitch or roll direction. It reflects the maximum maneuverability that the UAV body 1 can withstand in terms of design or operation, and is an important boundary condition for evaluating the stability of the airframe. This limit value can be set according to the design specifications of the UAV body 1, the performance parameters of the flight control system, or actual operating experience. For example, it can be set as the maximum attitude angular velocity allowed by the flight control system, or it can be conservatively set according to the structural strength and load characteristics of the UAV body 1.

[0080] Characteristic response time Used to unify the dimensions of quantitative acceleration measures, it is defined as follows: It provides an intrinsic timescale related to the characteristic length of the medicine box and gravitational acceleration, enabling effective comparison and fusion of physical quantities with different dimensions within the model.

[0081] Characteristic response time Based on the characteristic length of the medicine box (unit ) and gravitational acceleration (unit The value is obtained by taking the square root of the ratio, and its dimension is strictly and uniformly defined as the time dimension. This time characteristic parameter is related to the real-time acquired flight trajectory accelerometer. (unit After multiplying, convert to the dimension of acceleration. This allows for dimensionless fusion with the acceleration term at the molecular end.

[0082] Flight trajectory accelerometer The jerk is the acceleration of the flight trajectory of the UAV body 1, which is collected in real time by the perception acquisition module. The jerk is the rate of change of acceleration, which directly reflects the degree of drastic change in the flight attitude and speed of the UAV body 1. It is an important external excitation source that causes violent shaking of the liquid. This parameter can be acquired in real time by the multi-axis inertial measurement unit (IMU) inside the flight control system of the UAV body 1, and provided to the main control unit after appropriate filtering and processing.

[0083] The arctangent mapping structure is a mathematical function structure used to map input parameters to an output range of 0 to 1. The arctangent function has good smoothness and boundedness, and can transform complex combinations of physical quantities into a unified, dimensionless robustness index, avoiding abrupt changes or divergence in calculation results, thereby ensuring the stability and usability of the model output.

[0084] Mechatronic robustness It is a dimensionless index output by the model, ranging from 0 to 1, used to quantitatively evaluate the cooperative stability between the UAV body 1 and the liquid sloshing. The higher the value, the better the machine-liquid cooperative robustness and the smaller the impact of liquid sloshing on the stability of the UAV body 1; conversely, the lower the value, the worse the robustness and the greater the impact of liquid sloshing on the stability of the UAV body 1.

[0085] Dynamic calculation of bias constant It is a preset constant used to prevent singular divergence in computation, and its unit is . Adding a small positive value to the denominator can prevent the model output from becoming infinite or uncertain when the denominator approaches zero, thereby improving the numerical stability of the model. This constant can be set empirically according to the actual system characteristics and numerical calculation requirements. For example, it can be set to a small positive value that is much smaller than the actual flight trajectory acceleration.

[0086] The machine-liquid co-robustness calculation module receives the liquid sloshing dissipation numbers output from the liquid sloshing dissipation calculation module. This parameter reflects the inherent damping capacity of the liquid medicine inside the main body 2 of the medicine tank; at the same time, it receives the frequency fluctuation-excitation sensitivity index output from the frequency fluctuation-excitation sensitivity calculation module. This parameter reveals the response characteristics of liquid sloshing to external stimuli. This module also incorporates preset pitch or roll angular velocity limits for the UAV body 1. To take into account the maneuverability boundary of the main body of the UAV 1, ensuring that the robustness assessment conforms to the actual operating envelope of the aircraft, and this module acquires the flight trajectory jerk data collected by the perception acquisition module in real time. This parameter directly reflects the degree of drastic change in the flight attitude and speed of the main body of the UAV, and is an important external excitation source that causes violent shaking of the liquid medicine.

[0087] To eliminate computational bias caused by different units of measurement, this module introduces characteristic response time. The flight trajectory jerk was normalized, and the above parameters were organically integrated through a machine-liquid cooperative robustness model with an arctangent mapping structure. This model incorporates the liquid sloshing dissipation coefficient. Regarding (1 minus frequency fluctuation - excitation sensitivity index) The average of the squared terms of the contents of the medicine box body 2 is calculated to reflect the inherent anti-shaking ability of the liquid inside the body under the current liquid level and physical properties.

[0088] At the same time, the pitch or roll angular velocity of the main body of the drone is limited. With normalized flight trajectory jerk Ratio calculations are performed to assess the degree of matching between the intensity of external excitation and the maneuverability of the UAV body 1. These complex physical parameters are then transformed into dimensionless machine-fluid cooperative robustness between 0 and 1 using the arctangent function. This mapping structure ensures the smoothness and stability of the calculation results, avoiding abrupt changes in the model output under extreme conditions.

[0089] Through the above operating mechanism, the machine-liquid collaborative robustness calculation module can assess the impact of liquid sloshing on the stability of the aircraft in real time and accurately under the current flight state. When the main body of the UAV 1 performs high-maneuvering actions, the flight trajectory acceleration... When the concentration increases, if the dissipation capacity of the drug solution is low or its sensitivity to stimuli is high, the calculated machine-liquid synergistic robustness will be affected. The decrease indicates that the stability of the aircraft is significantly affected by the sloshing of the propellant. Conversely, if the propellant has strong dissipation capacity and is not sensitive to excitation, even with a large acceleration in the flight trajectory, the machine-hydraulic stability will be better. It can also maintain a high level, enabling the main control unit to dynamically adjust the absolute air pressure in the air chamber according to the real-time state of the machine-liquid coordination. Therefore, when the UAV body 1 performs high-maneuvering actions such as start-up acceleration, emergency stop hovering, large-angle turns, and rapid terrain-following flight, the system can adjust the absolute air pressure in the air chamber in advance or synchronously according to the real-time calculated machine-liquid coordination robustness. This more effectively suppresses the violent shaking of the liquid surface by compressing it with the stiffness of the upper air cushion, significantly reduces the interference of center of gravity shift on flight attitude, improves the flight stability, control accuracy, and operational safety of the UAV body 1, and effectively reduces the risk of accidents caused by liquid impact.

[0090] The air cushion pressure optimization output module constructs an air cushion pressure optimization model with a logarithmic compensation structure to output the air cushion pressure above the target liquid surface; The air cushion pressure above the target liquid surface is composed of the initial air cushion pressure above the liquid surface and a nonlinear dynamic pressure compensation term. The core operation logic of the nonlinear dynamic pressure compensation term is as follows: construct a logarithmic function factor with the maximum allowable pressure of the medicine tank as the proportional coefficient. The independent variable inside the logarithmic function factor is driven by the square term of the degree of machine-liquid coupling loss and suppressed by the wall slip resistance coefficient. Thus, under the condition that the risk of a sharp increase in the working condition of reduced machine-liquid synergy robustness and weakened inner wall resistance, the nonlinear dynamic pressure compensation term can quickly generate logarithmic high pressure compensation feedback.

[0091] The air cushion pressure optimization output module is based on the preset initial air cushion pressure above the liquid surface. Maximum allowable pressurization of the medicine box The calculated machine-fluid cooperative robustness and wall slip resistance coefficient A logarithmically compensated air cushion pressure optimization model is constructed to output the air cushion pressure above the target liquid surface. Its dimensions are in the International Standard Unit (SI) for pressure. The formula for the air cushion pressure optimization model is:

[0092] Among them, algebraic terms It is configured to characterize the degree of machine-fluid coupling loss, which is obtained by subtracting the machine-fluid co-robustness from 1, and is used to drive the nonlinear dynamic boost compensation term to perform a logarithmic response.

[0093] The air cushion pressure optimization output module is a functional module. This module can be an independent hardware module, such as an embedded processor or FPGA, specifically designed to execute the air cushion pressure optimization algorithm; or, its function can be implemented through a software sub-module within the main control unit via programming.

[0094] Preset initial air cushion pressure above the liquid surface This refers to the reference air pressure value maintained above the liquid surface in the air chamber inside the main body 2 of the medicine box when the system is started or in a stable state.

[0095] The initial air cushion pressure It can be a fixed value determined through experiments or simulations during the system design phase and stored in the non-volatile memory of the main control unit; or it can be an initial value calibrated and set during system initialization based on factors such as the volume of the medicine box and the type of medicine.

[0096] Maximum allowable pressurization of the medicine box This refers to the initial air cushion pressure. Based on this, the maximum allowable pressure increase value of the internal air chamber of the main body 2 of the medicine box. This maximum pressure increase... The maximum pressure can be determined by safety margin calculation based on the structural strength, sealing performance, and performance limitations of the air pressure regulating actuator of the main body 2 of the medicine box; or, it can be determined by experimental testing without damaging the structure of the main body 2 of the medicine box, and the maximum pressurization amount can be set accordingly.

[0097] The calculated machine-fluid co-robustness It is a dimensionless parameter reflecting the robustness of the coupling between the UAV body 1 and the liquid sloshing under the current flight state. This machine-liquid cooperative robustness The robustness is calculated by the mechanical-hydraulic co-operational robustness calculation module in the anti-sway robustness control subsystem based on its internal model.

[0098] Wall slip resistance coefficient It is also a dimensionless parameter, characterizing the sliding resistance properties of the liquid medicine on the inner wall of the medicine tank body 2, and the sliding resistance coefficient of this wall. The wall slip resistance calculation module in the anti-sway robustness control subsystem calculates the optimal model for the air cushion pressure of the logarithmic compensation structure based on its internal model. This model is a mathematical model that uses a logarithmic function to represent the mechanical-hydraulic synergistic robustness. and wall slip resistance coefficient The input parameters are mapped to the compensation amount of the air cushion pressure. The model can implement the above formula by programming in the main control unit and perform real-time calculation using floating-point or fixed-point arithmetic.

[0099] Air cushion pressure above the target liquid surface It is the final target absolute air pressure value calculated and output by the air cushion pressure optimization output module, used by the air pressure regulating actuator to achieve the target air cushion pressure above the liquid surface in the air chamber inside the medicine tank body 2. The output of the air cushion pressure optimization model is directly transmitted to the air pressure regulation actuator as a control command.

[0100] in, The boost control gain coefficient and satisfying , This is a preset dimensionless constant for preventing singularities.

[0101] Boost control gain coefficient It is a dimensionless coefficient used to adjust the gain of the compensation term in the air cushion pressure optimization model, adapting it to different tank sizes and drug densities. This pressure control gain coefficient... Based on the characteristic length of the medicine box Drug solution density and gravitational acceleration Through the preset initial air cushion pressure The calculations are performed and stored in the main control unit.

[0102] Anti-singular dimensionless constant It is a preset, extremely small positive number used to prevent the denominator from being zero in the logarithmic compensation model, thereby avoiding singular divergence in the calculation. This constant can be set to an extremely small positive value during model design.

[0103] By preset initial air cushion pressure With the maximum allowable pressurization of the medicine box This serves as a benchmark, ensuring the physical boundaries of pressure regulation and leveraging the robustness of the mechanical-hydraulic synergy. The pressure is adjusted using negative feedback. When the system robustness is low, the model increases the compensation amount to improve the air cushion stiffness, thereby enhancing the ability to suppress liquid surface sloshing. At the same time, a wall slippage resistance coefficient is introduced. As a denominator term, it can nonlinearly correct the pressure compensation amplitude based on the interaction characteristics between the liquid and the tank wall, effectively avoiding excessive or insufficient pressure regulation under specific fluid conditions.

[0104] Boost control gain coefficient The introduction of this technology organically combines the geometric features of the medicine tank with the physical properties of the fluid, enabling pressure regulation to adapt to different medicine tank sizes and liquid densities. Through mathematical modeling of this logarithmic compensation structure, the system can achieve a smooth transition and precise application of the liquid sloshing suppression force while ensuring the stability of the aircraft attitude. This effectively solves the coupling contradiction between liquid sloshing and flight control under complex maneuvering conditions, and significantly improves the operational efficiency and safety of the UAV body 1.

[0105] The sensing and acquisition module includes at least: a level gauge installed inside the main body 2 of the medicine tank to collect liquid level height in a non-contact manner, and a multi-axis inertial measurement unit integrated inside the flight control system of the main body 1 of the UAV to output dynamic kinematic parameters. The air pressure regulating actuator includes at least: a bidirectional micro air pump and an absolute pressure sensor installed inside the air chamber. The main control unit receives the real-time feedback value from the absolute pressure sensor and forms a closed-loop comparison control loop with the calculated air cushion pressure above the target liquid surface, thereby generating control commands to drive the bidirectional micro air pump to perform pressurization or depressurization actions.

[0106] The perception and acquisition module is the input end of the entire control system. It is responsible for collecting the flight motion parameters of the UAV body 1 and the liquid status parameters of the medicine tank body 2 in real time. It provides accurate and real-time environmental and internal system status data for the subsequent main control unit and is the foundation for realizing intelligent control.

[0107] Among them, the non-contact level gauge is used to collect the liquid level height inside the main body 2 of the medicine tank, avoiding corrosion, contamination, or measurement errors that may be caused by direct contact with the medicine liquid, thus improving the reliability and lifespan of the measurement. Its implementation can be, but is not limited to, an ultrasonic level gauge, which measures the liquid level distance by emitting and receiving ultrasonic waves.

[0108] The multi-axis inertial measurement unit is integrated into the flight control system of the UAV body 1 and is used to output kinematic parameters. This unit can provide key flight data such as attitude, angular velocity, and acceleration of the UAV body 1, which is an important basis for evaluating the excitation source of liquid sloshing. Its implementation can be, but is not limited to: an inertial measurement unit composed of a three-axis gyroscope and a three-axis accelerometer to measure angular velocity and linear acceleration; or further integrated with a three-axis magnetometer to provide more accurate heading information.

[0109] The air pressure regulating actuator is the output end of the control system. It is responsible for dynamically adjusting the absolute air pressure in the air chamber of the main body of the medicine box according to the instructions of the main control unit. Its function is to convert control instructions into physical actions, which directly affect the stability of the liquid surface. Among them, the bidirectional micro air pump is used to perform dynamic pressurization or depressurization actions. This means that the air pump can both inflate the air chamber to increase the pressure and depressurize the air chamber to decrease the pressure, thereby achieving precise bidirectional regulation of the air chamber pressure. The implementation methods can include, but are not limited to: using a diaphragm pump driven by a DC motor to control the airflow by changing the motor speed and direction; or using a piston pump with solenoid valve to control the intake and exhaust of air to achieve rapid pressure response.

[0110] An absolute pressure sensor is installed inside the air chamber to provide real-time feedback of the absolute air pressure value within the chamber. This sensor is a key component of closed-loop control, providing the main control unit with the current actual air pressure data for error comparison and correction. Its implementation methods can include, but are not limited to: a silicon piezoresistive sensor based on MEMS technology, which features small size, fast response, and high accuracy; or a ceramic capacitive sensor, which offers good long-term stability and corrosion resistance.

[0111] The main control unit receives the real-time value from the absolute pressure sensor and compares it with the calculated air cushion pressure above the target liquid surface. By performing a difference comparison, a closed-loop control circuit is formed. This unit is responsible for processing the sensed data, executing the control algorithm, and outputting control commands.

[0112] The closed-loop control circuit compares the real-time feedback value of the absolute pressure sensor with the target air cushion pressure to generate an error signal, and adjusts the action of the bidirectional micro air pump according to the error signal. This feedback mechanism can continuously correct the system output, ensure that the air chamber pressure accurately tracks the target value, and effectively suppress external disturbances and internal uncertainties of the system.

[0113] The pulse width modulation (PWM) signal is the signal type output by the main control unit, used to drive the bidirectional micro air pump. Pulse width modulation (PWM) is a technique that controls the average power output by adjusting the duty cycle of a square wave signal. It enables fine-grained control of the air pump speed or valve opening, thereby precisely regulating the air pressure in the air chamber.

[0114] By installing a non-contact level gauge inside the main body 2 of the medicine tank, the key state parameter of the liquid level can be obtained in real time, accurately and without pollution. At the same time, the multi-axis inertial measurement unit integrated into the flight control system of the UAV main body 1 enables the system to directly and synchronously acquire the kinematic parameters of the UAV main body 1, ensuring a high degree of consistency between the sensing data and the flight state, thus providing a basis for the main control unit to accurately evaluate the excitation source of liquid sloshing.

[0115] At the execution end, by installing an absolute pressure sensor inside the air chamber, real-time monitoring of the air cushion pressure is achieved. The main control unit compares the real-time feedback value with the calculated target air cushion pressure, forming an efficient closed-loop control loop. This closed-loop mechanism can significantly improve the accuracy and response speed of air pressure regulation, effectively compensate for the nonlinearity, lag, and external disturbances of the bidirectional micro air pump during the execution process, and ensure that the actual air pressure inside the air chamber can accurately track the target value. By outputting a pulse width modulation signal from the main control unit to drive the bidirectional micro air pump, fine and dynamic regulation of the air chamber pressure is achieved. It can quickly suppress the violent sloshing of the liquid surface by pressurizing, and can also flexibly adapt to different flight conditions and liquid consumption by depressurizing. Thus, the complex liquid anti-sloshing theory is transformed into a stable, reliable, and efficient engineering control practice, which greatly improves the operational stability and safety of the UAV body 1 under high-maneuver flight.

[0116] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0117] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", 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. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0118] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pesticide tank for agricultural drones to prevent pesticide spraying from shaking, characterized in that, include: The main body of the medicine box (2) is suspended on the main body of the drone (1) and is used to carry the liquid medicine. A sealed air chamber is reserved above the liquid surface inside the main body of the medicine box (2). The perception acquisition module is used to acquire the flight motion parameters of the main body of the UAV (1) and the liquid state parameters of the medicine box (2) in real time. The main control unit is communicatively connected to the sensing and acquisition module and is configured to obtain the air cushion pressure above the target liquid surface through multi-physics field coupling calculation based on the acquired flight motion parameters and the liquid state parameters. The air pressure regulating actuator is connected to the main control unit and communicates with the air chamber of the medicine box body (2). It is used to dynamically adjust the absolute air pressure in the air chamber according to the air cushion pressure above the target liquid surface, so as to suppress the violent shaking of the liquid surface by pressing with the upper air cushion stiffness.

2. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 1, characterized in that: The main control unit is equipped with an anti-sloshing robust control subsystem, which includes, in sequence: a liquid sloshing dissipation calculation module, a wall slip resistance calculation module, a sloshing frequency-excitation sensitivity calculation module, a machine-liquid co-operation robustness calculation module, and an air cushion pressure optimization output module.

3. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 2, characterized in that: The liquid sloshing dissipation solution module constructs a liquid sloshing dissipation model with a rational fractional structure to obtain the dimensionless liquid sloshing dissipation number. The liquid sloshing dissipation number is configured to characterize the proportional relationship between the viscous friction and surface tension dissipation mechanism inside the fluid. Its calculation logic is as follows: the square of the zero-shear viscosity of the liquid is used as the numerator, and the sum of the square of the zero-shear viscosity of the liquid and the gravity-surface tension coupled dissipation term is used as the denominator; wherein, the gravity-surface tension coupled dissipation term is positively correlated with the Bond number, the liquid density, the liquid surface tension, and the characteristic length of the medicine box.

4. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 3, characterized in that: The wall slip resistance solution module constructs a wall slip resistance model with a trigonometric function coupling structure to obtain dimensionless wall slip resistance coefficients. The wall slip resistance coefficient is obtained by multiplying the roughness resistance factor and the contact angle wetting factor; wherein, the roughness resistance factor is configured as the square term of the sine function of the dimensionless inner wall surface roughness term, and the dimensionless inner wall surface roughness term is jointly determined by the inner wall surface roughness of the box and the thickness of the fluid viscous sublayer; the contact angle wetting factor is configured as the square term of the cosine function of half of the static contact angle between the liquid and the box wall.

5. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 4, characterized in that: The frequency-excitation sensitivity calculation module constructs a frequency-excitation sensitivity model with Lorentz resonance peak characteristics to obtain a dimensionless frequency-excitation sensitivity index. The calculation logic of the frequency sway-excitation sensitivity index is as follows: extract the square of the equivalent damping ratio of the system as the reference numerator, and the denominator is formed by adding the reference numerator and a deviation penalty term; the deviation penalty term represents the absolute degree of deviation of the current filling ratio from the critical resonance filling ratio of the system, and the critical resonance filling ratio is independently determined by the tank length-to-slenderness ratio to ensure that when the filling ratio approaches the critical resonance region, the frequency sway-excitation sensitivity index produces a nonlinear surge.

6. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 5, characterized in that: The machine-fluid synergistic robustness calculation module constructs a machine-fluid synergistic robustness model based on the arctangent function to obtain dimensionless machine-fluid synergistic robustness. The machine-liquid co-robustness model obtains the machine-liquid co-robustness by constructing a comprehensive independent variable and performing an arctangent normalization mapping on it; the comprehensive independent variable is the product of the state stability term and the motion impact term; the state stability term is configured as a fractional structure, the numerator of which is composed of the liquid sloshing dissipation number and the square of (1 minus the sloshing frequency-excitation sensitivity index), and the denominator is preset to a constant 2; the motion impact term is configured as the ratio of the limit angular velocity characteristic parameter of the UAV body (1) to the current actual flight trajectory jerk, and a preset dynamic calculation bias constant is introduced into the denominator of the ratio characteristic term to prevent calculation divergence.

7. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 6, characterized in that: The air cushion pressure optimization output module constructs an air cushion pressure optimization model with a logarithmic compensation structure to output the air cushion pressure above the target liquid surface. The air cushion pressure above the target liquid surface is composed of the initial air cushion pressure above the liquid surface and a nonlinear dynamic pressure compensation term. The core operation logic of the nonlinear dynamic pressure compensation term is as follows: construct a logarithmic function factor with the maximum allowable pressure of the medicine tank as the proportional coefficient. The independent variable inside the logarithmic function factor is driven by the square term of the degree of machine-liquid coupling loss and suppressed by the wall slip resistance coefficient. This allows the nonlinear dynamic pressure compensation term to quickly generate logarithmic-level high-pressure compensation feedback when the machine-liquid synergy robustness decreases and the risk of weakened inner wall resistance increases sharply.

8. The pesticide tank for preventing pesticide spraying from shaking in agricultural drones according to claim 7, characterized in that: The sensing and acquisition module includes at least: a level gauge installed inside the main body (2) of the medicine box to collect the liquid level height in a non-contact manner, and a multi-axis inertial measurement unit integrated inside the flight control system of the main body (1) of the plant protection drone to output dynamic kinematic parameters. The pressure regulation actuator includes at least a bidirectional micro air pump and an absolute pressure sensor installed inside the air chamber. The main control unit receives the real-time feedback value of the absolute pressure sensor and forms a closed-loop comparison control loop with the calculated air cushion pressure above the target liquid surface, thereby generating a control command to drive the bidirectional micro air pump to perform pressurization or depressurization actions.

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