A micro air vehicle based on a flexible circuit board and an integrated design method thereof

Abstract

The present application relates to the technical field of micro air vehicle overall design, in particular to a micro air vehicle based on flexible circuit board and an integrated design method thereof, and the technical points are as follows: the method comprises the following steps: S1, basic flight control circuit selection; S2, functional expansion of flight control circuit; S3, modeling and plane expansion optimization of air vehicle shell; S4, structural adaptation modification of circuit; S5, flexible circuit processing and integrated shaping.The present application realizes deep integration of structure and avionics, improves space utilization and light weight level.The present application takes the flexible circuit board as a carrier, integrates the avionics system directly on the surface of the air vehicle shell, saves the independent installation cabin, fixing support and other redundant structures required by the traditional rigid PCB, effectively compresses the volume and structure weight of the air vehicle, can carry more functional components under the same size constraint, and breaks through the performance bottleneck of miniaturization and self-automation of micro air vehicles.

Description

Technical Field

[0001] This invention relates to the field of overall design technology for micro-miniature aircraft, specifically to a micro-miniature aircraft based on a flexible circuit board and its integrated design method. Background Technology

[0002] Flexible printed circuit boards (FPCs) are printed circuit boards made of flexible insulating substrates (usually polyester film or polyimide). By embedding circuit designs onto a thin, flexible plastic sheet, a large number of precision components can be packed into narrow and limited spaces, forming flexible circuits. These circuits can be bent freely, assembled three-dimensionally, have high wiring density, are lightweight when folded, small in size, have good heat dissipation, and are easy to install, breaking through the limitations of traditional interconnection technologies. Compared with conventional printed circuit boards (PCBs), FPCs have significant advantages in product design and reliability, making them suitable for miniaturized and thin electronic products. FPCs can be classified according to the number of layers into single-layer FPCs, double-layer FPCs, multi-layer FPCs, and rigid-flex boards. Related manufacturing technologies are based on single-layer FPC manufacturing technology, achieved through lamination and bonding. Flexible printed circuit boards have a long history of development and high technological maturity. In terms of processing, domestic FPC processing is quite mature; Shandong-based Mflex became the world's third-largest FPC manufacturer in 2018. In addition, the domestic FPC design, processing and manufacturing, and surface mount assembly industry chain for various smaller-scale products is also quite complete.

[0003] Miniature Air Vehicles (MAVs) represent a high-tech field encompassing multiple interdisciplinary areas. Since the concept of MAVs was formally proposed in the 1990s, their small size, light weight, stealth capabilities, and high flexibility have propelled them from numerous toy-like designs for remote-controlled flight to the development of practical systems. Based on flight principles and according to flight modes and overall structural layout, existing MAVs are generally classified into three main types: fixed-wing MAVs, flapping-wing MAVs, and rotary-wing MAVs. Although research on MAVs is still in its early stages, particularly the research and design of centimeter-level micro-aircraft, and there is still a significant gap between miniaturization and practical application, the promising application prospects and value of MAVs determine their vast future development potential.

[0004] In 2013, EPFL's CurvACE artificial compound eye system broke with conventional manufacturing and assembly methods, cleverly combining a microlens array with a flexible printed circuit board, significantly reducing the space required for the entire sensing system. In 2015, the German company FESTO launched a biomimetic ant robot manufactured using 3D printing (laser sintering) (the circuitry is functional rather than decorative). This integrated design method allowed the robot to maintain a complex shape while increasing the effective circuit area, enabling it to accommodate more electronic components and giving it a high degree of autonomous collaboration.

[0005] In existing technologies, integrated design concepts have been applied to some microelectromechanical systems (MEMS), such as artificial compound eye systems that combine microlens arrays with flexible circuit boards, and biomimetic robots that combine 3D printing with integrated circuits, all of which have reduced system size to some extent. However, these solutions are all designed for specific robot and sensing system scenarios and have not yet formed a standardized FPC integrated design process adapted to the flight control requirements of micro-miniature aircraft. Currently, micro-miniature aircraft generally use rigid PCBs as avionics carriers, requiring independent design of mounting bays and fixed structures. This results in low space utilization, high structural redundancy, and poor surface adaptability, which has become a core bottleneck restricting the miniaturization and autonomous development of micro-miniature aircraft. Summary of the Invention

[0006] The purpose of this invention is to provide a micro-miniature aircraft based on a flexible circuit board and its integrated design method to solve the problems mentioned in the background: Currently, micro-miniature aircraft generally use rigid PCBs as avionics carriers, which require independent design of installation cabins and fixed structures. This results in problems such as low space utilization, high structural redundancy, and poor surface adaptability, which have become the core bottleneck restricting the miniaturization and autonomous development of micro-miniature aircraft.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On one hand, this invention provides an integrated design method for micro-miniature aircraft based on flexible circuit boards, comprising the following steps:

[0009] S1. Basic Flight Control Circuit Selection: Based on the flight type and control requirements of the target micro-aircraft, a mature flight control circuit board with readily available circuit schematics is selected as the basic modification platform. The selected basic flight control circuit board is equipped with a main control chip that meets the flight control computation requirements and has reserved multiple peripheral interfaces, including at least communication interfaces, power interfaces, and general-purpose I / O interfaces. The circuit topology complexity is adapted to flexible fabrication and modification requirements. For special scenarios where no mature open-source solutions are available, a custom-designed basic flight control core circuit can be used as an alternative.

[0010] S2. Flight Controller Circuit Functional Expansion: Based on the input / output interfaces reserved on the basic flight controller circuit board, new functional module circuits are added according to the target functional requirements, while maintaining the original topology of the flight controller core circuit. Functional expansion only achieves electrical connection of the new modules through the peripheral interfaces natively reserved on the basic flight controller circuit board, without modifying the internal wiring and component layout of the original flight controller core circuit. New functional modules include, but are not limited to, visual perception modules, satellite positioning modules, and wireless communication modules, which are invoked through the driver interfaces of the existing flight controller firmware.

[0011] S3. Aircraft Shell Modeling and Planar Development Optimization: A 3D model of the target micro-aircraft's shell structure is created. While meeting the requirements of the shell structure and aerodynamic functions, the curvature of the shell surface is optimized to generate a flattened planar development diagram of the shell. This step specifically includes:

[0012] S31. Based on the aerodynamic shape parameters, structural size constraints and assembly reference requirements of the target micro-sized aircraft, establish a three-dimensional curved surface model of the outer shell and clarify structural features such as wall thickness, mounting hole positions, and assembly reference.

[0013] S32. With the optimization goal of reducing surface curvature and increasing the effective area of ​​the unfolded plane, the surface curvature of the three-dimensional model of the shell is smoothed and simplified, while retaining the core aerodynamic profile and structural installation reference. For micro and small aircraft flying at low speeds, the surface complexity can be further reduced to improve the plane regularity.

[0014] S33. Perform surface unfolding operation on the optimized three-dimensional shell model, control the surface stretching distortion rate within the allowable range of the process, and generate a non-overlapping and wrinkle-free planar unfolded diagram, which is used as the design benchmark for the flexible circuit board.

[0015] S4. Circuit Structure Adaptation and Modification: Based on the outline dimensions and curvature distribution of the unfolded shell, adjust the circuit board dimensions and component placement without altering the original electrical function. The circuit board shape adjustment and component placement should follow these rules:

[0016] (1) Large components with low curvature: Calculate the package size of all components and set a threshold. Arrange large components that exceed the threshold in the plane area with curvature close to 0 in the shell plane unfolding diagram to avoid bending stress damage to components and ensure SMT assembly yield.

[0017] (2) IMU coordinate system compatibility: Strictly maintain the relative positional relationship between the mounting plane and orientation of the IMU inertial measurement unit and the coordinate system of the aircraft body, and be consistent with the IMU mounting reference of the original flight control circuit, so that the original attitude calculation and state estimation algorithms can be directly reused;

[0018] (3) Edge restricted area reservation: A wiring restricted area of ​​a preset width is reserved at the physical edge of the circuit board. No wiring or components are arranged in the restricted area, which is used to adapt to the mounting hole position, structural bonding and edge reinforcement.

[0019] This step and step S3 can be iteratively optimized multiple times until the casing performance and circuit layout meet the design requirements.

[0020] S5. Flexible Circuit Fabrication and Integration: Flexible circuit board technology is used to fabricate the circuitry. The fabricated flexible circuit board is then integrated and fixed to the aircraft's outer shell structure, achieving integrated assembly of the avionics system and mechanical structure. The flexible circuit board is fabricated using any one or more of the following process solutions:

[0021] (1) Conventional FPC solution: single or multilayer flexible circuits are made using polyimide or polyester flexible insulating substrates. They have excellent bending performance and can be closely fitted to high curvature surfaces, making them suitable for aircraft scenarios with high shape complexity. After processing, they are bonded to the outer shell surface with structural adhesive.

[0022] (2) Double-layer separable adhesive FPC solution: The circuit is split into two sub-boards according to the functional partitions, which are respectively attached to the inner and outer surfaces of the shell. Metallized vias are preset at the corresponding positions of the shell. The electrical connection between the two sub-boards is achieved through low-temperature soldering process, which can make full use of the space on both sides of the shell and increase the usable area of ​​the circuit.

[0023] (3) FPC solution with structural reinforcement: PI or FR4 reinforcement sheets are pasted in the non-component arrangement area of ​​the flexible circuit board to improve the local structural rigidity. The reinforcement area corresponds to the position of the core components and external interface to ensure the stability of component installation and the strength of interface operation.

[0024] On the other hand, the present invention provides a micro-miniature aircraft based on a flexible circuit board, which is prepared by the above-mentioned integrated design method and includes an aircraft shell body and a flexible flight control circuit assembly; the flexible flight control circuit assembly is attached and integrated on the surface of the aircraft shell body, and the flexible flight control circuit assembly integrates a flight control core circuit and an extended function circuit, and the component arrangement is adapted to the curvature distribution of the shell surface.

[0025] Furthermore, the flexible flight control circuit assembly has a PI reinforcement structure in the area corresponding to the core components, and the IMU inertial measurement unit is located in the planar area corresponding to the reinforcement structure.

[0026] Furthermore, a flexible circuit board is attached to the inner and outer surfaces of the aircraft shell body, and the two flexible circuit boards are electrically interconnected through metallized vias on the shell.

[0027] Furthermore, the flexible flight control circuit assembly has mounting holes on its edge, which are fixedly connected to the aircraft shell body by mechanical fasteners.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention achieves deep integration of structure and avionics, improving space utilization and lightweighting. Using a flexible circuit board as a carrier, the avionics system is directly integrated onto the aircraft's outer shell surface, eliminating the redundant structures such as independent mounting bays and fixed supports required by traditional rigid PCBs. This effectively reduces the aircraft's size and structural weight, allowing for the installation of more functional components within the same size constraints, thus overcoming the performance bottlenecks in miniaturization and autonomy of micro-aircraft.

[0030] This invention is based on a mature flight control system, significantly reducing development difficulty and iteration costs. It modifies a mature open-source flight control circuit, preserving the core circuit topology and control algorithm compatibility. Integration is achieved solely through shape adaptation and flexible fabrication, eliminating the need to develop flight control hardware and software from scratch, thus greatly shortening the development cycle. Furthermore, iterations only require adjustments to the circuit layout and FPC shape, making the modification cost far lower than the traditional structure + PCB re-molding solution.

[0031] This invention balances surface adaptability with manufacturing reliability, ensuring stable flight control performance. Through shell surface optimization and component partitioning strategies, large-size components are placed in low-curvature areas, satisfying surface fitting requirements while ensuring high-yield patch manufacturing. Simultaneously, it strictly maintains the IMU sensor's mounting standards, allowing direct reuse of mature flight control algorithms and avoiding the workload of recalibration and debugging, thus maintaining the reliability and control accuracy of the flight control system.

[0032] The process solutions of this invention are flexible and combinable, with a wide range of applications. This invention supports the use of various process solutions, such as conventional FPC, dual-layer split FPC, and reinforced FPC, either individually or in combination. It can adapt to the shape characteristics and functional requirements of different types of micro and small aircraft, such as fixed-wing, rotor, and flapping-wing aircraft, and has extremely strong scene adaptability and scalability. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the integrated design method for micro-miniature aircraft based on flexible circuit boards according to the present invention.

[0034] Figure 2 This is a schematic diagram of the original circuit of the Pixhawk FMUv3 flight controller in an embodiment of the present invention;

[0035] Figure 3 This is a three-dimensional model and a planar unfolded schematic diagram of the shell of a miniature unmanned helicopter in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram illustrating the design requirements for circuit structural modifications in an embodiment of the present invention;

[0037] Figure 5 This is a diagram showing the completed circuit design in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the processing result of FPC with PI structure reinforcement in an embodiment of the present invention;

[0039] Figure 7 This is a schematic diagram illustrating the verification results of the double-layer separable adhesive FPC solution in an embodiment of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Please see Figure 1 As shown in the figure, the integrated design method for micro-miniature aircraft based on flexible circuit boards described in this embodiment is implemented as follows:

[0042] S1. Basic Flight Control Circuit Selection:

[0043] Based on the flight mode, flight control precision requirements, and computing power requirements of the target micro-sized aircraft, a flight control circuit board with publicly available circuit schematics and high technological maturity was selected as the basic modification carrier.

[0044] The selection process follows three core principles: First, the principle of computing power adaptation, the main control chip must meet the computational requirements of attitude calculation, position closed-loop control and autonomous navigation, and ensure the real-time performance and stability of the flight control system; second, the principle of sufficient interfaces, multiple communication interfaces including at least UART, I2C and SPI, as well as power interfaces and general IO interfaces, must be reserved to provide a hardware foundation for future functional expansion; third, the principle of controllable complexity, the overall circuit topology complexity should not be too high, and the number of components and wiring density must be compatible with the processing technology of flexible circuit boards to ensure the feasibility of modification.

[0045] For special application scenarios where there is no suitable mature open source solution, a basic flight control core circuit can be designed independently as an alternative.

[0046] S2. Functional expansion of flight control circuit:

[0047] Based on the selected basic flight control circuit board, the circuit functionality is expanded according to the target aircraft's requirements for extended functions such as perception and detection, data transmission, and mission payload.

[0048] The expansion process strictly adheres to the principle of "minimal modification": electrical connections for new functional modules are achieved only through the peripheral interfaces natively reserved on the basic flight controller circuit board, without any alteration to the internal wiring, component parameters, or layout of the original flight controller core circuit. New functional modules include, but are not limited to, a visual perception module, a satellite positioning module, a wireless data transmission module, and a mission payload drive module. The power, communication, and control pins of each module are connected to the reserved interfaces on the basic flight controller board, and function calls and data interaction are achieved through the standard driver interfaces of the existing flight controller firmware.

[0049] This expansion method can minimize the impact of the modification on the stability of the original flight control system, fully retain the proven control performance and reliability of the mature flight control system, and at the same time significantly reduce the workload of circuit debugging.

[0050] S3. Aircraft hull modeling and planar unfolding optimization:

[0051] S31. 3D modeling of the outer shell: Based on the aerodynamic design parameters, overall size constraints, internal assembly references and installation interface requirements of the target micro-sized aircraft, a complete curved surface model of the outer shell is established using 3D modeling software to clarify key structural features such as the wall thickness distribution, mounting hole coordinates, and assembly positioning references of the outer shell.

[0052] S32. Surface Curvature Optimization: While ensuring the aerodynamic performance, structural strength, and assembly functionality of the outer shell, the curvature of the outer shell is smoothed and simplified. The optimization goal is to reduce the bending angle of high-curvature surfaces, increase the proportion and area of ​​continuous planar regions, and reduce the difficulty of subsequent flexible circuit bonding and component placement limitations. For micro- and small aircraft with low flight speeds and low aerodynamic shape sensitivity, the surface complexity can be further reduced, prioritizing the regularity of the unfolded plane.

[0053] S33. Planar Unfolding Generation: A geometric surface unfolding algorithm is used to unfold the optimized 3D shell model. During the calculation, the stretching distortion rate of the surface is controlled within the range allowed by the flexible circuit board process to generate a planar unfolded diagram without overlap, wrinkles, or stretching damage. The outer contour and curvature distribution data of this planar unfolded diagram are used as the core benchmark for subsequent flexible circuit board shape design and component layout.

[0054] S4. Circuit structure adaptation and modification:

[0055] Based on the unfolded planar diagram of the outer casing obtained in step S3, while fully preserving the original electrical connections, component parameters, and functional performance, the outer contour and component arrangement of the circuit board are adaptively adjusted, specifically following the following three core rules:

[0056] (1) Large component low curvature arrangement rule: Calculate the package size of all components, set a package side length threshold, and arrange large components exceeding the threshold in a planar area with curvature close to 0 in the planar unfolded diagram. This rule can avoid stress concentration during circuit board bending that could damage components, while ensuring the yield and soldering accuracy of SMT assembly.

[0057] (2) IMU coordinate system compatibility rule: Strictly maintain the relative positional relationship between the mounting plane normal of the IMU inertial measurement unit, the device orientation, and the coordinate system of the aircraft body, and be completely consistent with the IMU mounting reference of the original flight control circuit. This rule allows the attitude calculation, data fusion, and state estimation algorithms in the original flight control firmware to be directly reused without the need for recalibrating parameters and debugging algorithms, greatly reducing the development workload.

[0058] (3) Edge Restricted Area Reservation Rules: A blank wiring restricted area with a width of not less than 2mm shall be reserved at the physical edge of the circuit board. No conductive traces or components shall be placed within the restricted area. This restricted area is used to accommodate mounting hole processing, structural bonding and fixing, and edge reinforcement treatment, so as to avoid damage to circuit traces during assembly and improve structural reliability.

[0059] This step and step S3 can be iteratively optimized in multiple rounds, gradually adjusting the shell surface shape and circuit layout scheme until the shell aerodynamic / structural performance and circuit layout effect meet the design requirements.

[0060] S5. Flexible circuit fabrication and integration:

[0061] After completing the circuit schematic and layout design, flexible circuit board technology is used for fabrication, followed by structural integration and electrical assembly with the aircraft shell. Depending on the aircraft's shape, functional requirements, and usage scenarios, one or more of the following process solutions can be selected for implementation:

[0062] (1) Conventional FPC solution: Single-layer or multi-layer flexible circuit boards are made using polyimide flexible insulating substrate. The core advantage of this solution is its excellent bending performance, which can closely fit the complex curved surface of the shell with high curvature, making it suitable for micro and small aircraft scenarios with high shape complexity and large surface curvature. After processing, high-temperature resistant structural adhesive is used to bond and fix the flexible circuit board to the inner surface of the shell, completing the integrated electrical and structural integration.

[0063] (2) Double-layer separable adhesive FPC solution: The overall circuit is divided into two independent sub-boards according to functional partitions, which are respectively attached to the inner and outer surfaces of the housing. Metallized vias are pre-set at corresponding positions on the housing, and the electrical connection between the two sub-boards is achieved through the vias using a low-temperature soldering process. This solution can make full use of the surface space on both sides of the housing, greatly increasing the usable area of ​​the circuit, and is suitable for high-integration scenarios with a large number of components and where the space on one side cannot meet the layout requirements.

[0064] (3) FPC solution with structural reinforcement: In the blank areas of the flexible circuit board where no components are placed, PI reinforcement sheets are pasted to improve the structural rigidity and flatness of the local area. The reinforcement area corresponds to the core chip, external interface and SD card slot, which can avoid the transfer of bending stress to sensitive devices, and at the same time ensure the structural strength of frequent operations such as connector insertion and removal and memory card insertion and removal. It is suitable for scenarios with high requirements for external operation and component stability.

[0065] Specific Implementation: Integrated Design of Micro-sized Unmanned Helicopters Based on FPC

[0066] This embodiment takes a micro-sized unmanned helicopter as the design object and carries out an integrated design with reference to the external dimensions of the Langyu M1 helicopter. The specific implementation process is as follows:

[0067] Basic Flight Controller Selection: The Pixhawk FMUv3 open-source flight controller was selected as the basic circuit platform. This flight controller is equipped with an STM32F427 main control chip, providing ample computing power for helicopter flight control and rich peripheral interfaces. The official complete circuit schematic is publicly available, indicating high technological maturity. Since the flight controller's functions fully cover the autonomous control requirements of the micro unmanned helicopter, no functional expansion is needed; we can directly proceed to the structural adaptation stage. The original circuit is as follows: Figure 2 As shown.

[0068] Shell Modeling and Planar Unfolding: A 3D model of the shell of the micro-sized unmanned helicopter was established. Considering the low cruising speed of this helicopter and the relatively small impact of aerodynamic shape on flight performance, the shell surface was significantly simplified. The final planar unfolded diagram was optimized into a regular "T"-shaped structure to maximize the effective planar area. Figure 3 As shown.

[0069] Circuit structural modification: Based on the outline and curvature distribution of the T-shaped planar unfolded diagram, the original flight control circuit is structurally redesigned, with design requirements as follows: Figure 4 As shown, the specific layout rules are as follows:

[0070] (1) The MICROSD card slot is placed on the left cover area of ​​the outer surface, with the interface facing the edge, for easy insertion and removal.

[0071] (2) Place the CON-DF17-80F connector on the right cover area of ​​the outer surface;

[0072] (3) The USB interface module MOLEX-47346-0001 is placed on the top cover area of ​​the outer surface, with the interface facing the right edge;

[0073] (4) Arrange the QFN-24, HMC5983, and MS5611-01BA chips in the planar area of ​​the inner surface top cover;

[0074] (5) Arrange the TQFP100 main control chip, SO08, TQFP48, crystal oscillator, QFN8-DSG and other devices in the low curvature area of ​​the inner surface top cover;

[0075] (6) The area within 3mm of the edge of the T-shaped circuit board is designated as a no-wiring zone, and no wiring or components are arranged there.

[0076] The completed circuit design results are as follows: Figure 5 As shown.

[0077] Flexible fabrication and integrated assembly: The circuit is fabricated using FPC technology with PI structure reinforcement. PI reinforcement sheets are placed in the main control chip and external interface areas to increase local rigidity. The flexible circuit board is fixed to the helicopter shell body by edge drilling and screw fastening, completing the integrated assembly. The processing result is as follows: Figure 6 As shown.

[0078] Furthermore, this embodiment also verifies the dual-layer, separable, adhesive FPC solution. A long, strip-shaped dual-layer circuit is attached to the inner and outer surfaces of the housing, with electrical connections achieved through through-holes in the housing. This further expands the usable circuit area. The verification results are as follows: Figure 7 As shown.

[0079] This embodiment demonstrates that by adopting the integrated design method of the present invention, the volume of the avionics system of a micro-helicopter can be reduced by more than 40% and the structural weight reduced by 30% without compromising flight control performance. At the same time, the cost of iterative modification is only 25% of that of traditional solutions, effectively achieving a balance between miniaturization and autonomous performance.

[0080] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An integrated design method for micro-miniature aircraft based on flexible circuit boards, characterized in that, Includes the following steps: S1. Basic flight control circuit selection: Based on the flight type and control requirements of the target micro-sized aircraft, select a mature flight control circuit board with available circuit schematics as the basic modification carrier. S2. Functional expansion of flight control circuit: Based on the input and output interfaces reserved on the basic flight control circuit board, new functional module circuits are added according to the target functional requirements, while keeping the original topology of the core flight control circuit unchanged. S3. Aircraft Shell Modeling and Planar Development Optimization: Perform 3D modeling of the shell structure of the target micro-aircraft, optimize the curvature of the shell surface under the premise of satisfying the shell structure and aerodynamic functions, and generate a flattened shell planar development diagram. S4. Circuit structure adaptation and modification: Based on the outline dimensions and curvature distribution of the shell planar unfolded diagram, adjust the circuit board size and component layout without changing the original electrical function. S5. Flexible Circuit Fabrication and Integration: The circuit is fabricated using flexible circuit board technology. The fabricated flexible circuit board is then integrated and fixed with the aircraft's outer shell structure to achieve integrated assembly of the avionics system and the mechanical structure.

2. The integrated design method for micro-miniature aircraft based on flexible circuit boards according to claim 1, characterized in that, In step S1, the selected basic flight control circuit board is equipped with a main control chip that meets the flight control computing requirements, and reserves multiple peripheral interfaces including at least a communication interface, a power interface and a general IO interface. The circuit topology complexity is adapted to the requirements of flexible processing and modification.

3. The integrated design method for micro-miniature aircraft based on flexible circuit boards according to claim 1, characterized in that, In step S2, the functional expansion is achieved by simply using the peripheral interfaces natively reserved on the basic flight control circuit board to make electrical connections to the new modules, without modifying the internal wiring and component layout of the original flight control core circuit.

4. The integrated design method for micro-miniature aircraft based on flexible circuit boards according to claim 1, characterized in that, Step S3 specifically includes: S31. Based on the aerodynamic shape parameters, structural size constraints and assembly reference requirements of the target micro-sized aircraft, establish a three-dimensional curved surface model of the outer shell; S32. With the optimization goal of reducing the curvature of the surface and increasing the effective area of ​​the unfolded plane, the curvature of the three-dimensional model of the shell is smoothed and simplified, while retaining the core aerodynamic contour and structural installation reference. S33. Perform surface unfolding operation on the optimized 3D shell model to generate a non-overlapping, non-stretching distortion planar unfolded diagram, which is used as the design benchmark for the flexible circuit board.

5. The integrated design method for micro-miniature aircraft based on flexible circuit boards according to claim 1, characterized in that, In step S4, the circuit board shape adjustment and component arrangement follow the following rules: (1) Arrange components with package sizes larger than a preset threshold in a planar region where the curvature approaches 0 in the unfolded diagram of the housing; (2) Maintain the relative positional relationship between the installation coordinate system of the IMU inertial measurement unit and the coordinate system of the aircraft body, and be compatible with the original flight control state estimation algorithm; (3) A wiring no-go zone of a preset width is reserved at the edge of the circuit board outline to accommodate the mounting hole positions and structural fixing requirements.

6. The integrated design method for micro-miniature aircraft based on flexible circuit boards according to claim 1, characterized in that, In step S5, the flexible circuit board is processed using any one or more of the following process solutions: Conventional FPC solutions: Use flexible insulating substrates to fabricate single-layer or multi-layer flexible circuits to adapt to high curvature surface bonding scenarios; Double-layer separable adhesive FPC solution: Two flexible circuit sub-boards are fabricated and attached to the inner and outer surfaces of the outer shell, respectively, and electrical connections are achieved through pre-set metallized vias in the outer shell; FPC solution with structural reinforcement: Reinforcing sheets are attached to non-component placement areas of the flexible circuit board to improve local structural rigidity and component installation stability.

7. A micro-sized aircraft based on a flexible circuit board, characterized in that, The micro-miniature aircraft, based on a flexible circuit board integrated design method according to any one of claims 1-6, is prepared and includes an aircraft shell body and a flexible flight control circuit assembly. The flexible flight control circuit assembly is bonded and integrated onto the surface of the aircraft shell. The flexible flight control circuit assembly integrates the core flight control circuit and the extended function circuit, and the component arrangement is adapted to the curvature distribution of the shell surface.

8. A micro-miniature aircraft based on a flexible circuit board according to claim 7, characterized in that, The flexible flight control circuit assembly has a PI reinforcement structure in the area corresponding to the core components, and the IMU inertial measurement unit is located in the planar area corresponding to the reinforcement structure.

9. A micro-miniature aircraft based on a flexible circuit board according to claim 7, characterized in that, The inner and outer surfaces of the aircraft's outer shell are each fitted with a flexible circuit board, and the two flexible circuit boards are electrically interconnected through metallized vias on the outer shell.

10. A micro-miniature aircraft based on a flexible circuit board according to claim 7, characterized in that, The flexible flight control circuit assembly has mounting holes on its edges and is fixedly connected to the aircraft shell body by mechanical fasteners.

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