Pressure-induced color change grounding shielding assembly for plant protection unmanned aerial vehicle peristaltic pump and monitoring method thereof

Abstract

The application provides a piezochromic grounding shielding assembly for a plant protection unmanned aerial vehicle peristaltic pump and a monitoring method thereof, and relates to the technical field of unmanned aerial vehicles. The shielding assembly comprises a multilayer composite structure of a conductive metal substrate layer, a piezochromic functional layer, a transparent conductive protective layer and an anti-corrosion sealing layer. The piezochromic functional layer adopts a polydiacetylene-silver nanowire composite system and undergoes reversible blue-red phase transition under the action of grounding contact pressure. The monitoring method comprises the following steps: periodically collecting images of the color-changing area by an onboard miniature CMOS camera, extracting chromaticity parameters in the CIE Lab color space, establishing a chromaticity-grounding impedance mapping model, realizing four-level grading evaluation of grounding quality, and reporting in real time to a ground station through a flight control system. The application simultaneously provides passive visual indication and active digital monitoring dual functions without increasing the wiring and power supply burden, and significantly improves the reliability and maintainability of the shielding system of the plant protection unmanned aerial vehicle peristaltic pump.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) technology, specifically to a pressure-sensitive color-changing grounding shielding component for a peristaltic pump used in agricultural UAVs and its monitoring method. Background Technology

[0002] As a core piece of equipment in modern precision agriculture, agricultural drones have been widely used in the prevention and control of pests and diseases in major crops such as rice, wheat, and cotton. Peristaltic pumps, due to their valveless structure, strong self-priming ability, and low shear force on pesticide solutions, have become a key fluid delivery device in the spraying systems of small and medium-sized agricultural drones. Peristaltic pumps achieve positive displacement delivery of pesticide solution through the periodic compression of elastic tubing by rollers. When their drive motors operate, they generate broadband electromagnetic interference (EMI) covering a frequency range of tens of kilohertz to several megahertz. This interference affects the drone's flight control system, navigation receiver, remote control link, and data transmission channels to varying degrees through both conduction and radiation.

[0003] In the complex electromagnetic environment of low altitude, agricultural drones face multi-source electromagnetic coupling from ground base stations, high-voltage transmission lines, neighboring drones, and their own onboard equipment. The peristaltic pump drive module, as one of the strong electromagnetic radiation sources onboard, directly affects the electromagnetic compatibility (EMC) performance of the entire drone through its electromagnetic shielding and grounding quality. Relevant domestic and international standards (such as GB / T35237 and MIL-STD-461G) impose stringent requirements on the limits of conducted and radiated emissions from airborne electronic equipment. However, agricultural drones operate under harsh conditions such as high vibration, high humidity, and pesticide corrosion for extended periods. Consequently, the grounding connections of their shielding components are prone to degradation, including increased contact resistance, oxidation of contact surfaces, and loosening of fasteners, leading to a significant decrease in shielding effectiveness (SE).

[0004] Piezochromic materials are a class of intelligent functional materials that undergo reversible optical property changes under mechanical pressure. Typical systems include organic conjugated polymer-based materials (such as polyacetylene), inorganic crystal-based materials (such as lead halide perovskite quantum dots), and organic-inorganic hybrid materials. These materials can transform invisible mechanical states into color changes that are perceptible to the naked eye, showing broad application prospects in structural health monitoring, flexible sensing, and other fields. However, no precedent has yet been found in publicly available literature and patent databases for combining them with electromagnetic shielding grounding monitoring.

[0005] Existing Solution 1: Traditional metal casing shielding plus fixed bolt grounding scheme. The peristaltic pump drive circuit board is encapsulated in an aluminum alloy or galvanized steel casing, which is connected to the rack grounding copper busbar by bolts, achieving integrated electrical grounding and electromagnetic shielding. This scheme relies on periodic manual checks of bolt tightening torque to maintain grounding quality, lacking real-time indication of grounding status.

[0006] Existing Solution 2: Conductive rubber sealing gasket plus conductive tape grounding solution. A conductive silicone rubber gasket is laid on the mating surface of the shielding shell to achieve 360° circumferential electromagnetic sealing, while conductive copper foil tape is adhered to the outer surface of the shell to lead to the grounding point. This solution improves the gap leakage problem, but the elasticity of the conductive rubber decreases under vibration and aging, and the grounding impedance increases after the contact pressure decreases, and the degree of attenuation cannot be visually judged from the outside.

[0007] Existing Solution 3: Online Grounding Resistance Monitoring Instrument Solution. This solution involves installing miniature online grounding resistance monitoring sensors to periodically report grounding loop impedance data to the ground station. While this solution enables data-driven monitoring, it increases system wiring complexity and adds weight. The sensors themselves also require power supply and communication links, and cannot provide grounding status information during power outages or communication interruptions.

[0008] Based on the above-mentioned existing technology, the following problems exist: Disadvantage 1: Grounding status is not visible. Traditional metal bolt grounding schemes and conductive rubber sealing schemes cannot provide operators or onboard systems with a direct visual indication of the grounding connection quality. Maintenance personnel can only rely on periodic disassembly and inspection or the use of specialized instruments to measure grounding impedance, which is costly and untimely. In high-frequency take-off and landing scenarios in field operations, EMI problems caused by grounding degradation are often only discovered after an accident occurs.

[0009] Disadvantage 2: High additional costs associated with monitoring methods. While online grounding resistance monitoring instruments can achieve digital monitoring, they require additional sensors, power lines, and communication cables, increasing system weight (typically by 30-80g) and wiring complexity. This is detrimental to the stringent requirements of agricultural drones for lightweight and simple wiring. Furthermore, the monitoring instruments themselves are prone to failure, creating new weaknesses in reliability.

[0010] Disadvantage 3: Inability to simultaneously achieve shielding and sealing while maintaining condition awareness. While existing conductive rubber gasket solutions can provide good initial electromagnetic sealing performance, the elastic modulus of the gasket continuously decreases under the effects of vibration fatigue and chemical aging, resulting in a reduction in contact pressure and an increase in ground contact resistance from the initial milliohm level to the ohm level or even higher. Operators cannot visually detect this degradation process.

[0011] Disadvantage 4: Insufficient resistance to pesticide corrosion. The working environment of agricultural drones contains highly acidic or alkaline pesticide mists, which easily cause electrochemical corrosion on traditional copper / aluminum contact surfaces, accelerating the degradation of grounding performance. Furthermore, the degree of corrosion lacks visual indication. Summary of the Invention

[0012] To address the shortcomings of existing technologies, the present invention aims to provide a pressure-sensitive color-changing grounding shielding component and its monitoring method for peristaltic pumps used in agricultural drones, thereby solving the problems mentioned in the background art. The present invention embeds a pressure-sensitive color-changing functional layer into the grounding contact surface of the shielding component, converting the mechanical pressure state of the grounding connection into a color signal that is visually perceptible or recognizable by an onboard miniature camera. This achieves passive visual indication of grounding quality with zero additional wiring and zero additional power supply. Simultaneously, it provides an active monitoring method based on color space analysis, enabling quantitative assessment and graded early warning of grounding degradation, comprehensively improving the reliability and maintainability of the peristaltic pump shielding system for agricultural drones under harsh operating conditions.

[0013] To achieve the above objectives, the present invention provides the following technical solution: a piezochromic grounding shielding assembly for a peristaltic pump of an agricultural drone. The shielding assembly consists of four functional layers stacked together, arranged sequentially from the grounding contact surface outwards: a conductive metal substrate layer, a piezochromic functional layer, a transparent conductive protective layer, and an anti-corrosion sealing layer. The piezochromic functional layer is a composite film formed by dispersing poly(diacetylene) microcrystals and silver nanowires in an elastic polymer matrix. The upper surface of the shielding assembly is provided with a light-transmitting observation window. The conductive metal substrate layer is removed from the observation window area, but the piezochromic functional layer, the transparent conductive protective layer, and the anti-corrosion sealing layer are retained. The metal substrate layer around the observation window forms a ring-shaped conductive bridge to maintain the continuity of the grounding current path.

[0014] Furthermore, the pressure-sensitive color-changing functional layer is an interpenetrating network composite film formed by blending poly(diacetylene) microcrystals and silver nanowires in a polyurethane elastic matrix. The poly(diacetylene) microcrystals, acting as a force-color response unit, undergo a reversible phase transition under normal contact pressure, resulting in a shortening of the main chain conjugate length and exhibiting a blue-to-red phase transition. The silver nanowires form a three-dimensional interpenetrating conductive network, acting as a force-electric synergistic unit. They undergo elastic deformation synchronously with the elastic matrix, ensuring the free volume required for the reversible color change of the poly(diacetylene) (PDA) microcrystals while maintaining the topological continuity of the lateral conductive pathways through the slippage and re-overlapping of the nanowires. This ensures that the sheet resistance of the pressure-sensitive color-changing functional layer is no greater than 5 Ω / sq when subjected to grounding pressure, thus achieving a dual-function synergy of mechanical pressure-responsive color change and grounding current conduction within the same thin layer.

[0015] Furthermore, the shielding assembly is a rectangular plate structure, and its external dimensions are customized according to the dimensions of the grounding flange of the peristaltic pump housing. The shielding assembly has M3 mounting through holes at its four corners, and the shielding assembly is pressed between the peristaltic pump housing flange and the grounding copper busbar of the frame by stainless steel bolts.

[0016] Furthermore, the conductive metal substrate layer around the observation window is formed into a ring-shaped conductive bridge through chemical etching to ensure that grounding current does not pass through the observation window area; The cross-sectional area of ​​the annular conductive bridge satisfies ,in The minimum safe cross-sectional area of ​​the substrate corresponding to the rated grounding current of the peristaltic pump; and the width of the annular conductive bridge. ≥5mm, to ensure that in the light-transmitting area of ​​the window in the conductive metal substrate, the skin effect current of high-frequency electromagnetic interference flows only through the annular bridge surface without shielding failure. At the same time, the silver nanowire network with a sheet resistance of ≤5Ω / sq in the piezochromic functional layer retained in the observation window area provides a second parallel grounding shunt path to achieve compatibility between optical observation window and shielding grounding integrity. It also includes an airborne miniature CMOS camera, which is mounted on the outside of the peristaltic pump housing, with the lens facing the observation window and a working distance of 15-25mm.

[0017] Furthermore, the conductive metal substrate layer is made of beryllium bronze plate with a thickness of 0.3 to 0.5 mm, and the surface is treated with nickel plating.

[0018] Furthermore, the transparent conductive protective layer is made of flexible indium tin oxide sputtered film or PEDOT:PSS conductive polymer film, with a thickness of 120-200 nm, visible light transmittance ≥82%, and sheet resistance ≤50 Ω / sq.

[0019] Furthermore, the anti-corrosion sealing layer is made of silicone-modified fluorocarbon resin coating with a thickness of 10-15 μm, which is used to block acid and alkali mist from corroding the underlying material, and the anti-corrosion sealing layer has a fully transparent structure. This layer has selective air permeability and liquid barrier properties, blocking the intrusion of acid and alkali mist droplets, but allowing micro-permeation of environmental water vapor. When long-term pesticide corrosion causes local micropores or microcracks in the anti-corrosion sealing layer, trace amounts of acid and alkali ions penetrate along the microcracks and preferentially undergo electrochemical oxidation with the silver nanowires on the surface of the pressure-induced color-changing functional layer. This leads to a local increase in sheet resistance and a change in the optical reflectivity of the nanowires in this area, causing a characteristic shift in the hue angle acquired by CMOS (such as a decrease in hue angle saturation) before significant mechanical loosening occurs. Thus, through the electrochemical degradation response of the color-changing layer, an early warning of the grounding corrosion degradation trend can be achieved.

[0020] A monitoring method using the above-mentioned shielding components, the monitoring method including two working modes: passive visual indication mode and active digital monitoring mode; in: The passive visual indication mode is as follows: before and after each flight, the operator visually inspects the color of the observation window area of ​​the shielding component. The active digital monitoring mode is as follows: the airborne miniature CMOS camera acquires images of the observation window area at programmable cycles during flight.

[0021] Furthermore, in the passive visual indication mode, if the color of the observation window area of ​​the shielding component is dark red or purplish red, it indicates that the grounding connection is in good or qualified condition; if it is bluish-purple, it indicates that maintenance needs to be arranged; if it is blue, it indicates that the grounding has basically failed and the aircraft must be grounded for inspection.

[0022] Furthermore, in the active digital monitoring mode, the image undergoes the following processing chain by the flight control processor: region of interest cropping, white balance correction, RGB to CIE Lab color space conversion, chromaticity parameter extraction, hue angle calculation, comparison with a preset threshold, generation of four-level grounding status evaluation results, and reporting to the ground station via the data transmission link; When the grounding status is detected to drop to the warning or failure level, the flight control system automatically triggers an audible and visual alarm and displays a prompt on the ground station interface.

[0023] The beneficial effects of this invention are: This invention provides zero-power passive visualization of grounding status. The piezochromic layer directly converts the mechanical pressure state of the grounding contact surface into a color signal, providing maintenance personnel with an intuitive visual indication of grounding quality without any power supply or electronic components. This remains effective even in extreme situations such as depleted battery power, communication interruption, or electronic system failure of agricultural drones, significantly outperforming traditional monitoring solutions that rely on active sensors. This invention possesses dual-mode monitoring capabilities, both active and passive. Based on passive visual indication, it integrates an airborne CMOS camera and a CIE Lab color analysis algorithm to achieve quantitative, digital, and remote monitoring of grounding status, along with a four-level tiered early warning system, providing data support for operational and maintenance decisions. The shielding, grounding, and sensing functions are integrated into one. The AgNW conductive network in the pressure-sensitive color-changing functional layer simultaneously plays the dual role of maintaining conductivity continuity and carrying out color changes. This achieves a high degree of integration of electromagnetic shielding, electrical grounding, and status sensing functions in the same thin-layer structure, eliminating the need for additional wiring and sensor installation. Lightweight and miniaturized. The total thickness of the shielding components is only about 1.2mm, with an added weight of less than 8g (including four M3 stainless steel bolts), having minimal impact on the payload margin of the agricultural drone. The CMOS camera can reuse the drone's existing onboard vision hardware or be installed independently in a very small size (typical weight <3g).

[0024] Its resistance to harsh working conditions is significantly enhanced. The outermost fluorocarbon resin sealing coating (water contact angle > 110°) effectively blocks the corrosion of pesticide acid and alkali mists, mud, and water vapor, extending the service life of the shielding components. At the same time, the color degradation of the discoloration layer can indicate the trend of corrosion deterioration in advance, enabling preventive maintenance. The shielding effectiveness is synergistically improved. In the L2 layer, the AgNW network provides conductivity, while its high aspect ratio nanowire structure provides an additional absorption loss of 3-8 dB in the 100 MHz to 1 GHz frequency band, further improving the overall shielding effectiveness on the basis of the L1 metal substrate. Attached Figure Description

[0025] Figure 1 An overview of the electromagnetic shielding and grounding system architecture for peristaltic pumps used by agricultural drones; Figure 2 An exploded view (top) and an installation view (bottom) of the multi-layer composite structure of the shielding component. Figure 3 This is a diagram showing the relationship between the piezoelectric color-changing principle and the color mapping of the grounding state. Figure 4 Flowchart for proactive digital monitoring methods; Figure 5 The equivalent circuit topology diagram for the grounding loop of the shielding component; Figure 6 Top view of the shielding component installation location and monitoring hardware layout assembly diagram. Figure 7 Cross-sectional diagram of the multi-layered synergistic mechanism of electromagnetic shielding effectiveness; Figure 8 This is a thermo-spectral comparison of the shielding effectiveness of the three schemes in this embodiment; Figure 9 The color response matrix diagram of the compressive color-changing layer is cyclically loaded (each cell represents the measured color); Figure 10 To verify the accuracy of grounding degradation monitoring, a confusion matrix was used (50 independent decisions). Figure 11 This is a comparison diagram showing the evolution of pesticide corrosion resistance and durability of three schemes in the embodiments of the present invention. Detailed Implementation

[0026] 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.

[0027] Please see Figures 1 to 11This invention provides the following technical solution: a pressure-sensitive color-changing grounding shielding component for a peristaltic pump in agricultural drones and its monitoring method. This invention is applicable to various agricultural drones (including multi-rotor and fixed-wing-multi-rotor hybrid configurations) that use peristaltic pumps as pesticide delivery devices, and is particularly suitable for small and medium-sized agricultural drone platforms with a pesticide load of 5–30L and a flight altitude of 1.5–15m. The shielding component described in this invention can be applied to the peristaltic pump drive circuit board housing, the peristaltic pump motor housing, and the electrical interconnection area between them. It can also be extended to other modules of agricultural drones that require electromagnetic shielding and visual monitoring of grounding quality (such as ESC housings, communication module housings, etc.).

[0028] The shielding assembly of this invention mainly consists of the following four functional layers, arranged in order from the grounding contact surface outwards: (1) Conductive metal substrate (L1): Beryllium bronze (CuBe2) plate with a thickness of 0.3 to 0.5 mm is selected, which has excellent elasticity and conductivity (conductivity ≥26% IACS). The surface is treated with nickel plating (nickel layer thickness 3 to 5 μm) to improve corrosion resistance. The substrate layer undertakes the main electromagnetic shielding function and also serves as a conduction path for grounding current.

[0029] (2) Pressure-sensitive color-changing functional layer (L2): An interpenetrating network composite film formed by blending poly(diacetylene) microcrystals and silver nanowires in a polyurethane elastic matrix; wherein, the poly(diacetylene) microcrystals, as force-color response units, undergo a reversible phase transition with shortening of the main chain conjugate length under normal contact pressure, exhibiting a blue-red phase transition; the silver nanowires form a three-dimensional interpenetrating conductive network, as force-electric synergistic units, which undergo elastic deformation synchronously with the matrix in the elastic matrix, while ensuring the free volume required for the reversible color change of the PDA microcrystals, the topological continuity of the transverse conductive path is maintained by the slippage and re-overlapping of the nanowires, so that the sheet resistance of the layer is not greater than 5Ω / sq when subjected to grounding pressure, thus realizing the dual-function synergy of mechanical pressure response color change and grounding current conduction within the same thin layer.

[0030] (3) Transparent conductive protective layer (L3): Flexible ITO (indium tin oxide) sputtered thin film or PEDOT:PSS conductive polymer thin film with a thickness of 120-200 nm, visible light transmittance ≥82%, and sheet resistance ≤50Ω / sq. This layer protects the underlying color-changing layer from mechanical scratches, while ensuring that the color-changing information can be collected by the optical sensor above without obstruction.

[0031] (4) Anti-corrosion sealing layer (L4): The coating is made of silicone-modified fluorocarbon resin with a thickness of 10-15 μm. This layer has selective air permeability and liquid blocking properties, which prevents acid and alkali mist droplets from entering, but allows micro-permeation of environmental water vapor. When long-term pesticide corrosion causes local micropores or microcracks to be generated in the anti-corrosion sealing layer, trace amounts of acid and alkali ions penetrate along the microcracks and preferentially undergo electrochemical oxidation with the silver nanowires on the surface of the pressure-induced color-changing functional layer. This leads to a local increase in sheet resistance and a change in the optical reflectivity of the nanowires in this area, causing a characteristic shift in the hue angle acquired by CMOS before significant mechanical loosening occurs (such as a decrease in hue angle saturation). Thus, through the electrochemical degradation response of the color-changing layer, an early warning of the grounding corrosion degradation trend can be achieved.

[0032] This embodiment also provides a detailed structural description of the above-mentioned components as follows: The shielding assembly is a rectangular plate structure, with dimensions customized to the size of the peristaltic pump housing grounding flange (typical dimensions are 45mm × 30mm × 1.2mm). M3 mounting holes are located at the four corners of the assembly, allowing stainless steel bolts to be used to press the shielding assembly between the peristaltic pump housing flange and the frame grounding copper busbar. After installation, the bolt preload is transmitted through the beryllium bronze base layer to the pressure-sensitive color-changing layer, creating a uniformly distributed contact pressure field that causes the color-changing layer to display an initial color corresponding to the pressure (deep red under normal preload).

[0033] A circular observation window with a diameter of 12mm is formed on the upper surface (facing outward) of the shielding assembly. Only layers L2, L3, and L4 are retained in the observation window area, while the L1 metal substrate is removed to create a light-transmitting channel. The L1 substrate layer surrounding the observation window is chemically etched to form a ring-shaped conductive bridge, ensuring that grounding current does not pass through the observation window area, thus not affecting the overall grounding performance. The cross-sectional area of ​​the ring-shaped conductive bridge meets the following requirements. ,in The minimum safe cross-sectional area of ​​the substrate corresponding to the rated grounding current of the peristaltic pump; and the width of the annular conductive bridge. The distance is ≥ 5mm to ensure that in the light-transmitting area of ​​the conductive metal substrate window, the skin effect current of high-frequency electromagnetic interference flows only through the annular bridge surface without shielding disruption. Simultaneously, a second parallel grounding shunt path is provided using the silver nanowire network with a sheet resistance ≤ 5Ω / sq within the piezochromic functional layer retained in the observation window area, ensuring compatibility between the optical observation window and the shielding grounding integrity. An airborne miniature CMOS camera is mounted on the outside of the peristaltic pump housing, with the lens aligned with the observation window, at a working distance of 15–25mm.

[0034] This embodiment also provides a monitoring method for the above-mentioned shielding component: The monitoring method described in this invention includes two working modes: a passive visual indication mode and an active digital monitoring mode. Passive visual indication mode: Before and after each flight, the operator visually inspects the color of the observation window area of ​​the shielding assembly. A deep red or purplish-red color indicates a good or satisfactory grounding connection; a bluish-purple color indicates maintenance is required; and a blue color indicates that the grounding has essentially failed and the aircraft must be grounded for inspection. This mode requires no electronic assistance and is suitable for rapid field inspections.

[0035] Active Digital Monitoring Mode: The airborne miniature CMOS camera (640×480 resolution, 5fps frame rate) acquires images of the observation window area at programmable intervals (default every 60 seconds) during flight. The images undergo the following processing chain by the flight control processor: ROI (Region of Interest) cropping → white balance correction → RGB to CIELab color space conversion → chromaticity parameter (a*, b*) extraction → hue angle calculation → comparison with preset thresholds → generation of four-level grounding status assessment results → reporting to the ground station via data transmission link. When the grounding status is detected to drop to the "warning" or "failure" level, the flight control system automatically triggers an audible and visual alarm and displays a prompt on the ground station interface.

[0036] This embodiment also provides the core algorithm used in the above technical solution: Formula 1: Calculation Model for Multi-Layer Composite Shielding Effectiveness The total electromagnetic shielding effectiveness of the shielding assembly consists of four parts: reflection loss, absorption loss, multiple internal reflection correction terms, and viscoelastic additional loss of the compressive chromatic layer.

[0037] Formula 2: Hue angle of pressure-induced color change layer - contact pressure response model Based on the modified Sigmoid function, PDA microcrystals under normal contact pressure Hue angle The response is:

[0038] In the formula: blue The hue angle is blue (approximately 240°). red The hue angle is red (approximately 0° / 360°). This is the sensitivity coefficient. 0 represents the half-response threshold pressure. Formula 3: Contact Impedance-Contact Pressure Correlation Model Based on Holm's contact resistance theory, the contact impedance of the pressure-sensitive color-changing layer Contact pressure with normal direction Follows power-law decay:

[0039] In the formula: 0 represents the residual impedance of the substrate. The material contact coefficient, This is the roughness attenuation index.

[0040] Formula 4: Chromaticity-Impedance Composite Mapping Model By combining Equations 2 and 3, the intermediate physical quantity of contact pressure can be eliminated. Constructing from hue angle Directly mapped grounding impedance Explicit inversion function:

[0041] This formula shows that: hue angle can be extracted from CMOS images. This allows for the online inversion of unobservable grounding contact impedance. This enables cross-physical domain mapping from optical parameters to electrical safety parameters.

[0042] Formula 5: Comprehensive Evaluation Index of Grounding Quality Introducing the normalized grounding quality index Its calculation model is as follows:

[0043] In the formula: ( () represents the grounding impedance inverted from the hue angle at the current moment; max , min These are the impedance thresholds for failure and optimal states, respectively; |Δ / Δ | represents the absolute value of the rate of change of the hue angle over time, used to characterize transient chromaticity fluctuations caused by vibration and loosening; limit The maximum permissible chromaticity drift rate; ( The ambient temperature compensation coefficient is used to correct the hue angle temperature drift based on the embedded thermistor data of the CMOS camera. 1, 2, 3 is the weighting coefficient, and 1+ 2+ 3 = 1.

[0044] Formula 6: Four-level grading judgment criteria Based on the comprehensive evaluation index of grounding quality Three decision thresholds are set to achieve a four-level classification: Excellent (Level-1), Satisfactory (Level-2), Warning (Level-3), and Failure (Level-4).

[0045] In the formula: 1 — Excellent / Qualified threshold (typically 0.80); 2——Qualified / Warning Threshold (typically 0.50); 3 — Warning / Failure Threshold (typically 0.25). The threshold can be adjusted according to the specific aircraft model's EMC requirements and maintenance strategy. When the judgment result is Level-3 or Level-4, the system automatically triggers a flight control alarm and reports it to the ground station via the data transmission link.

[0046] This embodiment also provides the following alternatives: I. Replacement of Pressure-Induced Color-Changing Material System The polydiacetylene (PDA) microcrystals in the pressure-sensitive color-changing functional layer can be replaced with one of the following materials: (a) lead halide perovskite quantum dots (such as CsPbBr3), which undergo lattice compression under pressure, resulting in a blue shift in the band gap and exhibiting a green-blue color change, suitable for scenarios requiring different color identification systems; (b) spiropyran / spiroxazine mechanochromic molecules, which open their rings under mechanical force and produce a deep purple color, returning to colorless upon release, enabling a "colorless-colored" binary indication mode; (c) gold nanorod / elastomer composite film, utilizing the surface plasmon resonance peak shift caused by changes in the spacing of gold nanorods to achieve continuous color changes. The blending process of the above alternative material systems and the L3 / L4 protective layer structure remain unchanged.

[0047] II. Replacement of Transparent Conductive Protective Layer The flexible ITO film in the L3 layer can be replaced by: (a) a transparent conductive film made of silver nanowires, with a sheet resistance as low as 10 Ω / sq and better flexibility, but at a slightly higher cost; (b) a graphene transfer film, with a sheet resistance of about 100–500 Ω / sq and excellent chemical stability; and (c) a carbon nanotube network film. All of the above alternatives can meet the basic requirement of ≥80% transmittance.

[0048] III. Replacement of Color Acquisition Methods The airborne CMOS camera solution can be replaced by: (a) a miniature RGB color sensor (such as TCS34725), which directly outputs RGB values, eliminating the image processing step, but the spatial resolution is not as good as that of a camera; (b) a miniature spectral sensor (such as AS7341), which can acquire 8 channels of visible spectrum information to achieve more accurate colorimetric resolution; (c) a fiber optic coupling solution, which transmits the color signal of the observation window to the remote detection unit through polymer optical fiber, which is suitable for miniature UAVs with extremely limited installation space.

[0049] Based on the above technical solution, the present invention also provides the following experiments for verification: To objectively verify the innovativeness and effectiveness of this invention, the following four sets of experiments were designed. The experimental platform was a certain type of hexacopter agricultural drone (carrying 10L of pesticide), with a peristaltic pump model YZ15-A and a drive motor rated power of 24W. The control groups were: (Group A) traditional aluminum alloy shell + bolt grounding scheme, (Group B) conductive rubber gasket + copper foil tape grounding scheme, and (Group C) the pressure-sensitive color-changing shielding component scheme of this invention. All experiments were repeated 5 times under the same environmental conditions (temperature 25±2℃, humidity 60±10%RH), and the average value was taken.

[0050] Experiment 1: Comparison of Shielding Effectiveness Spectrum The shielding effectiveness (SE) of the three schemes was measured using a vector network analyzer (Keysight E5071C) in the range of 30MHz to 1GHz. The results show that Group A has an SE range of 35–52 dB; Group B has an SE range of 38–55 dB; and Group C (the present invention) has an SE range of 42–63 dB. In the core frequency band of 200MHz–800MHz, the average SE is approximately 11.4 dB higher than Group A and approximately 7.2 dB higher than Group B. This is mainly attributed to the additional absorption loss provided by the L2 layer AgNW network.

[0051] Experiment 2: Accuracy and Reversibility of Color Change Response Cyclic loads (load-unload rate 0.5 MPa / min) within the range of 0–4 MPa were applied to the shielding component of this invention using a precision mechanical testing machine. Simultaneously, a spectrophotometer was used to record the reflectance spectrum and calculate the CIELab hue angle. Experimental results show that the response curve of hue angle to contact pressure has a goodness of fit R with the Sigmoid model of formula (2). 2 >0.993; After 100 complete load-unload cycles, the hue angle drift at the same pressure point is <2°, proving that the color change is reversible.

[0052] Please see Figure 9 , Figure 9The colors displayed are high-fidelity digital representations derived from the real physical observation data in Experiment 2. In Experiment 2, a spectrophotometer was used to accurately record the reflectance spectra of the material under different pressure cycles, and the corresponding CIELab chromaticity coordinates were calculated. (Appendix) Figure 9 Each color cell in the array is generated using a standard color space conversion algorithm (such as CIELab to sRGB) based on the experimentally measured average CIELab coordinates.

[0053] therefore, Figure 9 Each cell color in the diagram is completely faithful to the "actual observation" results in Experiment 2. The purpose of using this digital color block format instead of a real photograph is to eliminate interference factors such as ambient light, shadows, and surface reflections, and to most objectively and purely reflect the intrinsic color change patterns and cyclic stability of the material, thereby confirming the conclusion that "after 100 complete load-unload cycles, the hue angle drift at the same pressure point is <2°".

[0054] Experiment 3: Grounding Degradation Simulation and Monitoring Accuracy Verification The grounding degradation process was simulated by gradually loosening the fixing bolts of the shielding assembly. Simultaneously, (a) the grounding loop resistance value directly measured by a multimeter (true value) and (b) the grounding impedance value estimated by the monitoring method of this invention through colorimetric analysis were recorded. Ten degradation levels were set up, ranging from fully tightened to fully loosened. The results show that the root mean square error (RMSE) between the grounding impedance estimated by the method of this invention and the true value is 3.2 mΩ, and the average relative error is 6.8%. The four-level classification decision has a 96% accuracy rate with the actual state (only 2 out of 50 decisions resulted in misjudgments of the qualified / warning boundary).

[0055] Experiment 4: Comparison of pesticide corrosion resistance and durability Three shielding / grounding components were immersed in a simulated pesticide solution (glyphosate isopropylamine salt aqueous solution) at pH=3 for accelerated corrosion testing. Every 24 hours, the components were removed to measure the grounding loop resistance and photographed to record their appearance. The experiment lasted 14 days. The results showed that: Group A's grounding resistance exceeded the warning value of 50mΩ on day 3 and exceeded 200mΩ on day 7; Group B exceeded 50mΩ on day 5 and exceeded 200mΩ on day 10; Group C (the present invention) showed a grounding resistance that only increased to 18mΩ after 14 days, remaining within the acceptable range, and the discoloration layer still responded normally to pressure changes.

[0056] Summary of comparative experiments Through the above four sets of comparative experiments, the significant advantages of this invention over existing technical solutions in four key dimensions—shielding effectiveness, color change reversibility, monitoring accuracy, and corrosion resistance and durability—were fully verified. Specifically: (1) the shielding effectiveness is improved by an average of 11.4 dB in the core frequency band; (2) the hue angle drift of the color-changing layer is less than 2° after 100 cycles; (3) the accuracy rate of the four-level grounding status classification judgment reaches 96%; and (4) the pesticide corrosion resistance life is extended by at least 2.5 times compared with the traditional solution. These experimental results fully demonstrate the innovation and practicality of this invention in the field of electromagnetic shielding and grounding visualization monitoring of peristaltic pumps of agricultural drones.

[0057] The foregoing has shown and described the basic principles and main features of the present invention and its advantages. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A pressure-sensitive color-changing grounding shielding assembly for a peristaltic pump used in agricultural drones, characterized in that: The shielding assembly consists of four functional layers, arranged sequentially from the grounding contact surface outwards: a conductive metal substrate layer, a piezochromic functional layer, a transparent conductive protective layer, and an anti-corrosion sealing layer. The piezochromic functional layer is a composite film formed by dispersing polyacetylene microcrystals and silver nanowires in an elastic polymer matrix. The upper surface of the shielding assembly is provided with a light-transmitting observation window. The conductive metal substrate layer is removed from the observation window area, but the piezochromic functional layer, the transparent conductive protective layer, and the anti-corrosion sealing layer are retained. The metal substrate layer around the observation window forms a ring-shaped conductive bridge to maintain the continuity of the grounding current path.

2. The pressure-sensitive color-changing grounding shielding assembly for the peristaltic pump of an agricultural drone according to claim 1, characterized in that: The pressure-sensitive color-changing functional layer is an interpenetrating network composite film formed by blending poly(diacetylene) microcrystals and silver nanowires in a polyurethane elastic matrix. The poly(diacetylene) microcrystals, acting as a force-color response unit, undergo a reversible phase transition under normal contact pressure, resulting in a shortening of the main chain conjugate length and a blue-to-red phase transition. The silver nanowires form a three-dimensional interpenetrating conductive network, acting as a force-electric synergistic unit. They undergo elastic deformation synchronously with the elastic matrix, ensuring the free volume required for the reversible color change of the poly(diacetylene) microcrystals while maintaining the topological continuity of the lateral conductive pathways through the slippage and re-overlapping of the nanowires. This ensures that the sheet resistance of the pressure-sensitive color-changing functional layer is no greater than 5 Ω / sq when subjected to grounding pressure, achieving a dual-function synergy of mechanical pressure-responsive color change and grounding current conduction within the same thin layer.

3. The pressure-sensitive color-changing grounding shielding assembly for the peristaltic pump of an agricultural drone according to claim 1, characterized in that: The conductive metal substrate layer around the observation window is formed into a ring-shaped conductive bridge by chemical etching to ensure that grounding current does not pass through the observation window area; The cross-sectional area of ​​the annular conductive bridge satisfies ,in The minimum safe cross-sectional area of ​​the substrate corresponding to the rated grounding current of the peristaltic pump; and the width of the annular conductive bridge. ≥ 5mm, to ensure that in the light-transmitting area of ​​the window in the conductive metal substrate, the skin effect current of high-frequency electromagnetic interference flows only through the annular bridge surface without shielding failure. At the same time, the silver nanowire network with a sheet resistance of ≤5Ω / sq in the piezochromic functional layer retained in the observation window area provides a second parallel grounding shunt path to achieve compatibility between optical observation window and shielding grounding integrity.

4. The pressure-sensitive color-changing grounding shielding assembly for the peristaltic pump of an agricultural drone according to claim 1, characterized in that: It also includes an airborne miniature CMOS camera, which is mounted on the outside of the peristaltic pump housing, with the lens facing the observation window and a working distance of 15-25mm.

5. The pressure-sensitive color-changing grounding shielding assembly for the peristaltic pump of an agricultural drone according to claim 1, characterized in that: The conductive metal substrate is made of beryllium bronze plate with a thickness of 0.3 to 0.5 mm and the surface is treated with nickel plating; the transparent conductive protective layer is made of flexible indium tin oxide sputtered film or PEDOT:PSS conductive polymer film with a thickness of 120 to 200 nm, visible light transmittance ≥82%, and sheet resistance ≤50Ω / sq.

6. The pressure-sensitive color-changing grounding shielding assembly for the peristaltic pump of an agricultural drone according to claim 1, characterized in that: The anti-corrosion sealing layer is made of silicone-modified fluorocarbon resin coating with a thickness of 10-15 μm. It is used to block acid and alkali mist from corroding the underlying material, and the anti-corrosion sealing layer has a fully transparent structure.

7. The pressure-sensitive color-changing grounding shielding assembly for the peristaltic pump of an agricultural drone according to claim 1, characterized in that: The shielding assembly is a rectangular plate structure, and its external dimensions are customized according to the dimensions of the grounding flange of the peristaltic pump housing. The shielding assembly has M3 mounting through holes at its four corners. The shielding assembly is pressed between the peristaltic pump housing flange and the grounding copper busbar of the frame by stainless steel bolts.

8. A monitoring method using the shielding component as described in claim 1, characterized in that: The monitoring method includes two working modes: passive visual indication mode and active digital monitoring mode. in: The passive visual indication mode is as follows: before and after each flight, the operator visually inspects the color of the observation window area of ​​the shielding component. The active digital monitoring mode is as follows: the airborne miniature CMOS camera acquires images of the observation window area at programmable cycles during flight.

9. The monitoring method according to claim 8, characterized in that: In the passive visual indication mode, if the color of the observation window area of ​​the shielding component is dark red or purplish red, it indicates that the grounding connection is in good or qualified condition; if it is bluish-purple, it indicates that maintenance needs to be arranged; if it is blue, it indicates that the grounding has basically failed and the aircraft must be grounded for inspection.

10. The monitoring method according to claim 9, characterized in that: In the active digital monitoring mode, the image is processed by the flight control processor in the following chain: region of interest cropping, white balance correction, RGB to CIE Lab color space conversion, chromaticity parameter extraction, hue angle calculation, comparison with preset threshold, generation of four-level grounding status evaluation results, and reporting to the ground station through the data transmission link; When the grounding status is detected to drop to the warning or failure level, the flight control system automatically triggers an audible and visual alarm and displays a prompt on the ground station interface.

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