Flexible transmission mechanism for a micro ornithopter and method thereof

Abstract

This invention discloses a flexible transmission mechanism and method for a micro flapping-wing aircraft, belonging to the field of micro aircraft. The mechanism includes a crank chain, a flapping-wing chain, a constraint chain, a reduction gear set, and a frame. The flapping-wing chain consists of a moving platform and two sets of mirror-symmetrical rocker mechanisms. Each rocker mechanism includes a transmission link, a flapping rod, and a fixed rod. The transmission link is hinged to the moving platform. The flapping rod has a wing interface. When the moving platform reciprocates, it drives the flapping rod to rotate around the hinge between the flapping rod and the fixed rod through the transmission link, thus realizing the flapping action. The constraint chain includes a fixed platform and two constraint branches, forming a complete Sarrus mechanism with the moving platform, constraining its movement only along the platform's normal linear direction. One end of the crank chain is connected to the moving platform, and the other end is connected to an external motor through the reduction gear set, converting continuous rotation into reciprocating driving force. This mechanism has significant advantages such as lighter weight, smaller size, greater structural rigidity, and lower transmission loss.

Description

Technical Field

[0001] This invention belongs to the field of micro aircraft, specifically relating to a flexible transmission mechanism and method for a micro flapping-wing aircraft. Background Technology

[0002] Flapping-wing aircraft are a type of aircraft designed to mimic the flapping flight principle of birds or insects in nature. Flapping-wing micro air vehicles (FW-MAVs) specifically refer to miniaturized flapping-wing aircraft in both size and weight, ranging from a few centimeters to tens of centimeters in size and from a few milligrams to tens of grams in weight. Compared to conventional micro fixed-wing and micro rotary-wing aircraft, FW-MAVs possess significant advantages such as small size, light weight, low noise, efficient transmission, and excellent biomimetic characteristics, demonstrating broad application prospects in many fields such as indoor reconnaissance and wilderness rescue.

[0003] Currently, commonly used transmission schemes for FW-MAVs mainly include gear-linkage drives, rope drives, and torsion spring drives. These transmission schemes are characterized by low material costs and stable transmission operation, and have formed mature and reliable transmission systems compatible with various mainstream motors and motor drives. However, as the size of FW-MAVs continues to shrink, the negative impact of frictional losses in the above-mentioned traditional transmission methods will be significantly amplified, leading to a substantial decrease in the overall transmission efficiency of the transmission mechanism. At the same time, the reduction in the overall size of FW-MAVs inevitably requires the simultaneous miniaturization of all components of the transmission mechanism, resulting in a decrease in structural strength and making the mechanism prone to structural damage under actual working conditions.

[0004] In contrast, flexible transmission mechanisms have become a superior technological choice for the miniaturization of FW-MAV. These mechanisms are manufactured using Smart Composite Micro-structure (SCM) technology. The core technology involves sandwiching and bonding a layer of flexible material (usually a polyimide film) between two layers of rigid material (typically carbon fiber plates) to form a flexible hinge revolute pair. Multiple such revolute pairs are then combined to form a complete flexible transmission mechanism. Compared to traditional transmission mechanisms, flexible transmission mechanisms offer advantages such as lighter weight, smaller size, and lower transmission losses, making them a preferred solution for miniaturized transmission scenarios. However, flexible hinges can only achieve reciprocating rotation and cannot achieve continuous rotation. Furthermore, the main load-bearing component during transmission is the flexible film, which has limited load-bearing capacity. Therefore, such flexible transmission mechanisms typically require the use of linear actuators with lower output force / torque, such as piezoelectric ceramic actuators, dielectric elastomer actuators, and electromagnetic coil actuators.

[0005] In summary: While the FW-MAV, designed and manufactured using the "motor + traditional transmission mechanism" approach, already possesses mature payload-carrying flight capabilities, its size is typically greater than 10cm and its weight greater than 10g due to the dual limitations of transmission mechanism efficiency and structural strength at the microscale, making further miniaturization difficult. On the other hand, the FW-MAV, designed and manufactured based on the "linear actuator + flexible transmission mechanism" approach, can achieve a size and weight close to that of real insects or birds, but it is limited by the output capacity of the linear actuator, preventing it from developing mature payload-carrying flight capabilities. Some products can even only operate in a tethered state, making it difficult to meet practical application requirements. Summary of the Invention

[0006] In the current design and manufacturing process of micro flapping-wing aircraft, traditional transmission mechanisms such as gear-linkage transmission, rope transmission, and torsion spring transmission are limited by friction loss and structural strength, making them unsuitable for the further miniaturization requirements of FW-MAVs. Existing flexible transmission mechanisms lack stable and reliable transmission solutions adapted to motor drives, making it difficult to balance miniaturization with the practicality of motor drives. The purpose of this invention is to solve these problems in the prior art and provide a flexible transmission mechanism and method for micro flapping-wing aircraft.

[0007] The specific technical solution adopted in this invention is as follows:

[0008] In a first aspect, the present invention provides a flexible transmission mechanism for a micro flapping-wing aircraft, which includes a crank chain, a flapping-wing chain, a constraint chain, a reduction gear set and a frame;

[0009] The flapping wing chain includes a moving platform and two sets of rocker mechanisms. Each set of rocker mechanisms consists of a transmission link, a flapping rod, and a fixed rod connected in sequence by hinges. The two sets of rocker mechanisms are connected to both sides of the moving platform in a mirror-symmetrical manner. The transmission link is hinged to the moving platform, and the fixed rod is fixedly assembled relative to the frame. The flapping rod is provided with an interface for connecting to the aircraft wing. During the reciprocating motion of the moving platform along the normal direction of the platform plane, the transmission link drives the flapping rod to rotate reciprocally about the hinge between the flapping rod and the fixed rod as the axis of rotation, thereby driving the wing to perform flapping action.

[0010] The constraint chain includes a fixed platform and two constraint branches connected to both sides of the fixed platform. The fixed platform is fixedly assembled on the frame and connected to the moving platform through the two constraint branches, thereby forming a complete Sarrus mechanism. The moving platform is constrained to only reciprocate linear motion along the normal of its platform plane.

[0011] One end of the crank chain is connected to the moving platform, and the other end is connected to a reduction gear set driven by an external motor, thereby converting the continuous rotation input from the external motor into a reciprocating driving force on the moving platform along the normal direction of the platform plane.

[0012] As a preferred embodiment of the first aspect, in the flapping wing chain, both the moving platform and the flapping rod have connecting sections on both sides of the main body plane, and the connecting sections are bent relative to the main body plane and then fixed by the first insert piece relative to the main body plane to form a U-shaped structure; the connecting sections on both sides of the moving platform are respectively connected to two transmission links in a hinged manner, and the connecting sections on both sides of each flapping rod are respectively connected to the transmission link and the fixed rod in the rocker mechanism.

[0013] As a preferred embodiment of the first aspect, in the constraint chain, the fixed platform is fitted onto the fixed rods on both sides of the flapping wing chain; and each constraint branch includes two constraint links, which are indirectly connected by a pair of second plug-in locking segments to form a hinge-like connection, and the axis of the hinge is parallel to the platform plane of the moving platform. Under the action of external force, the distance between the fixed end and the free end of the constraint link is adjusted by adjusting the opening angle. The free end of each constraint branch is provided with an interface for assembling and fixing the moving platform.

[0014] As a preferred embodiment of the first aspect, the crank chain includes a crank connecting rod, a bearing sleeve, a bearing, a rudder shaft, and a rudder disc. One end of the crank connecting rod is provided with a connecting section for assembling and fixing the moving platform in a hinged manner, and the other end is engaged with the bearing sleeve. The bearing sleeve houses an assembly of the bearing and the rudder shaft. The rudder disc has a shaft hole and a gear interface side by side. The bottom of the rudder shaft is assembled in the shaft hole. The output gear of the reduction gear set can be assembled into the gear interface to drive the rudder disc to rotate, thereby driving the moving platform to reciprocate along the normal direction of the platform plane through the crank connecting rod.

[0015] As a preferred embodiment of the first aspect, both the flapping wing chain and the restraint chain are integrally machined by SCM process and then folded and assembled. Their material is composed of a middle flexible layer and two hard layers on both sides. When there is a hinged connection between the sub-components inside each component, the middle flexible layer needs to be continuous while the two hard layers on both sides are broken and form a toothed interlacing structure, thereby forming a rotating hinge.

[0016] As a preferred embodiment of the first aspect, the crank connecting rod is integrally machined using SCM technology, and there is a hinge-like connection between the connecting section of the crank connecting rod used to assemble and fix the moving platform and the main body. During processing, the middle flexible layer must be kept continuous while the hard layers on both sides are broken and form a toothed interlacing structure, thereby forming a rotating hinge.

[0017] As a preferred embodiment of the first aspect mentioned above, in the SCM process, the flexible layer is made of polyimide film and the rigid layer is made of carbon fiber plate.

[0018] As a preferred embodiment of the first aspect above, the reduction gear set includes a multi-stage gear with cascaded meshing transmission, and each stage of gear adopts a double-layer cascaded gear; the reduction gear set is assembled and fixed on the frame by auxiliary components.

[0019] As a preferred embodiment of the first aspect, the frame is assembled from carbon fiber components by plugging them together, wherein an assembly structure for the drive motor and assembly slots for the flapping wing chain and reduction gear set are reserved.

[0020] Secondly, the present invention provides a flapping control method for a flexible transmission mechanism of a micro flapping-wing aircraft as described in the first aspect above. Specifically, a pair of wings of the aircraft are respectively mounted on two flapping rods of the flapping chain; an external motor is then controlled to drive a reduction gear set, thereby driving the moving platform to reciprocate linearly along its platform plane normal under the drive of the crank chain end and the constraint of the constraint chain; during the reciprocating motion along the platform plane normal, the moving platform drives the flapping rods to reciprocate around the hinge between itself and the fixed rod via a transmission link, thereby driving the wings mounted on the two flapping rods to perform flapping actions.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. This invention provides a flexible transmission mechanism for a micro flapping-wing aircraft, which adopts a coupled layout of multiple flexible transmission chains. Each flexible chain undertakes functions such as motion conversion, motion amplification, and motion constraint. This design can significantly reduce frictional losses during transmission, improve transmission efficiency, and prevent large deformation and instability of the flexible chains under high speed and high torque output conditions of the motor, thereby improving the stability and reliability of the mechanism.

[0023] 2. Compared with traditional transmission methods such as existing gear linkage mechanisms, rope drive mechanisms, and torsion spring mechanisms, this invention has significant advantages in terms of lighter weight, smaller size, and lower transmission losses. Compared with existing conventional flexible transmission mechanisms, this invention has greater structural rigidity and higher overall strength, and can stably adapt to the harsh operating conditions of continuous high-speed operation and high torque output of the motor. Therefore, this invention plays an important supporting and promoting role in promoting the miniaturization, lightweighting, and efficiency improvement of micro flapping-wing aircraft.

[0024] 3. The present invention adopts a plug-in high-rigidity lightweight carbon fiber frame structure composed of multiple components such as crossbeams, side beams, and side ribs. The main components are all made of carbon fiber materials. Under the premise of achieving structural lightweighting, the overall frame rigidity is greatly improved, which can effectively suppress the system vibration caused by motor operation and wing flapping, reduce the fatigue damage caused by vibration to the flexible hinges in the mechanism, and significantly improve the overall structural strength and service life of the mechanism. Attached Figure Description

[0025] Figure 1 The overall structure and exploded view of the flexible transmission mechanism of a micro flapping-wing aircraft;

[0026] Figure 2 The overall structure and exploded view of the flapping wing chain;

[0027] Figure 3 The overall structure of the constraint chain and its exploded view;

[0028] Figure 4 The overall structure of the crank chain and its exploded view;

[0029] Figure 5 The overall structure and exploded view of the reduction gear set;

[0030] Figure 6 This shows the overall structure of the framework and its exploded view.

[0031] Figure 7 A schematic diagram of a complete miniature flapping-wing aircraft after the motor and wings are assembled;

[0032] Figure 8 This is a schematic diagram showing the direction of motion of each component when the wing flaps counterclockwise;

[0033] Figure 9 This is a schematic diagram showing the direction of motion of each component when the wing flaps clockwise;

[0034] The reference numerals in the figure are as follows: Crank chain 1, flapping wing chain 2, constraint chain 3, reduction gear set 4, frame 5, wing 6, motor 7, crank connecting rod 101, bearing sleeve 102, bearing 103, rudder shaft 104, rudder disc 105, gasket 106, moving platform 201, transmission connecting rod 202, flapping rod 203, fixed rod 204, first insert piece 205, fixed platform 301, upper constraint branch 302, lower constraint branch 303, second insert piece 304, first gear 401, second gear 402, pivot pin 403, gasket 404, mounting base plate 405, base plate 501, side rib 502, lower crossbeam 503, upper crossbeam 504, side beam 505. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the present invention can be combined accordingly without mutual conflict.

[0036] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0037] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0038] like Figure 1 As shown, in a preferred embodiment of the present invention, a flexible transmission mechanism for a micro flapping-wing aircraft is provided. Its core structure includes five components: a crank chain 1, a flapping-wing chain 2, a constraint chain 3, a reduction gear set 4, and a frame 5. The structural forms of each of these five components and their assembly and actuation relationships are described in detail below.

[0039] like Figure 2 As shown, in the flexible transmission mechanism of the present invention, the flapping wing chain 2 includes a moving platform 201 and two sets of rocker mechanisms. Each set of rocker mechanisms is formed by a transmission link 202, a flapping rod 203, and a fixed rod 204 connected in sequence by hinges. The two sets of rocker mechanisms are connected to both sides of the moving platform 201 in a mirror-symmetrical manner. The transmission link 202 is hinged to the moving platform 201, the fixed rod 204 is fixedly assembled relative to the frame 5, and the flapping rod 203 is provided with an interface for connecting the aircraft wing. During the reciprocating motion of the moving platform 201 along the normal direction of the platform plane, the transmission link 202 drives the flapping rod 203 to rotate reciprocally about the hinge between the flapping rod 203 and the fixed rod 204 as the axis of rotation, thereby driving the wing to perform flapping action.

[0040] The aforementioned flapping chain is essentially a slider double rocker mechanism. Its function is to receive the reciprocating linear motion input from the crank chain 1 through the moving platform 201 and convert it into the reciprocating oscillating motion of the flapping rod 203.

[0041] It should be noted that, theoretically, the individual components of the flapping wing chain 2 can be individually processed and assembled to form the complete structure of the flapping wing chain 2. However, in the embodiments of this invention, the flapping wing chain 2 is integrally machined using the SCM process. The SCM process in this invention involves sandwiching and bonding a layer of flexible material (usually a polyimide film) between two layers of rigid material (usually a carbon fiber plate). Then, the rigid material is cut (generally using laser cutting) at the joint positions where rotation is required. The rigid material on both sides forms a serrated, staggered, discontinuous area, while the flexible material in the middle remains continuous, thus forming a flexible hinge rotating pair.

[0042] Of course, after the flapping wing chain 2 of the present invention is integrally planar processed by SCM technology, it still needs to be spatially folded in a specific way to enable it to perform corresponding operations. Moreover, based on the structural characteristics of the device processed by SCM technology, the physical interference between different sub-components during operation needs to be minimized when designing the layout for planar processing. For sub-components that may cause interference, additional connecting segments can be added at their connection positions to indirectly connect the two sub-components and avoid mutual interference during operation. At the same time, after spatial folding, the relative positional relationship of some sub-components can be fixed by plug-in pieces, so the plug-in pieces can also be included in the layout design.

[0043] See also Figure 2As shown in the embodiment of the present invention, both the moving platform 201 and the flapping rod 203 in the flapping wing chain 2 need to consider interference with the connected sub-components. Therefore, these two components have connecting sections on both sides of their respective main planes. After the connecting sections are bent relative to the main plane, they are fixed by first insert pieces 205 relative to the main plane, forming a U-shaped structure. After the connecting sections on both sides of the moving platform 201 are bent perpendicularly relative to the main plane, a first insert piece 205 needs to be inserted at the top and bottom to lock the relative spatial position relationship between the three, making it a U-shaped structure. Similarly, after the connecting sections on both sides of each flapping rod 203 are bent perpendicularly relative to the main plane, a first insert piece 205 needs to be inserted at the top and bottom to lock the relative spatial position relationship between the three, making it a U-shaped structure. Therefore, the flapping wing chain 2 as a whole needs to be designed with three pairs of first insert pieces 205 to complete the locking of its structural form after spatial bending. In the final locked flapping wing chain 2 structure, the moving platform 201 is located on the side of the fixed platform 301, which is built into the constraint chain 3, while the two flapping rods 203 are externally located on the side away from the constraint chain 3, for mounting a pair of wings. In addition, the connecting sections on both sides of the moving platform 201 and the flapping rods 203 serve as hinged positions with adjacent sub-components. That is, the connecting sections on both sides of the moving platform 201 are hinged to the two transmission links 202, and the connecting sections on both sides of each flapping rod 203 are hinged to the transmission link 202 and the fixed rod 204 in the rocker mechanism where the flapping rod 203 is located.

[0044] Meanwhile, it should be noted that in order for the flapping wing chain 2 to be assembled with components such as crank chain 1, constraint chain 3, and frame 5, in the embodiments of the present invention, an interface for connecting with crank chain 1 and constraint chain 3 needs to be reserved on the moving platform 201 of flapping wing chain 2, an interface for connecting with frame 5 needs to be reserved on the two side fixing rods 204, and an interface for connecting with wing needs to be reserved on flapping rod 203.

[0045] like Figure 3 As shown, in the flexible transmission mechanism of the present invention, the constraint chain 3 includes a fixed platform 301 and two constraint branches connected to both sides of the fixed platform 301, referred to as the upper constraint branch 302 and the lower constraint branch 303, respectively. The fixed platform 301 is fixedly mounted on the frame 5 and connected to the moving platform 201 through the two constraint branches, thereby forming a complete Sarrus mechanism, which constrains the moving platform 201 to only perform reciprocating linear motion along the normal direction of its platform plane.

[0046] It can be seen that the aforementioned constraint chain 3 is essentially a part of the Sarrus mechanism. It, together with the moving platform 201 of the flapping wing chain 2, constitutes a complete Sarrus mechanism. The constraint moving platform can only perform reciprocating linear motion along the normal of its platform plane.

[0047] It should be noted that, theoretically, each component in constraint chain 3 can be individually processed and assembled to form the complete structure of constraint chain 3. However, in the embodiments of this invention, constraint chain 3 is integrally machined using SCM (Surface Mount Technology) process. Of course, after constraint chain 3 is integrally machined using SCM process, it needs to be spatially folded in a specific manner to enable its corresponding actuation. Similar to flapping wing chain 2, based on the structural characteristics of devices processed using SCM process, the layout design for planar machining needs to minimize physical interference between different sub-components during actuation. For sub-components that may cause interference, additional connecting segments can be added at their connection points to indirectly connect the two sub-components, avoiding mutual interference during actuation. Simultaneously, after spatial folding, the relative positional relationship of some sub-components can be fixed using connectors; therefore, connectors can also be included in the layout design.

[0048] See also Figure 3 As shown, in this embodiment of the invention, the fixed platform 301 in the constraint chain 3 is not directly assembled to the frame 5, but is engaged with the fixing rods 204 on both sides of the flapping wing chain 2, thereby indirectly achieving a relatively fixed assembly with the frame 5. Of course, in other designs, the constraint chain 3 can also be directly assembled to the frame 5.

[0049] Additionally, see also Figure 3 As shown, the upper constraint branch 302 and lower constraint branch 303 in constraint chain 3 each include two constraint links. These two constraint links are not directly hinged together; instead, connecting segments are introduced to avoid interference and improve flexibility. Specifically, in each constraint branch, there are two connecting segments between the two constraint links. The first constraint link, the first connecting segment, the second connecting segment, and the second constraint link are sequentially connected by interlaced serrations to form a hinged connection. These two connecting segments are pressed together during folding, and then second insert pieces 304 are inserted on the left and right sides to achieve a locked fit. Thus, an indirect hinged connection between the two constraint links is achieved through this pair of connecting segments locked by the second insert pieces 304. Furthermore, in constraint chain 3, the axial direction of all hinges must be parallel to the plane of the main body of the ultimately connected moving platform 201, i.e., the platform plane. Under external force, the distance between the fixed and free ends of the two constraint links can be adjusted by changing the opening and closing angle. The fixed end of the constraint link refers to the end connected to the fixed platform 301, while the free end refers to the end connected to the moving platform 201. Since the axial direction of all the hinges in the constraint chain 3 is parallel to the moving platform 201, the reciprocating sliding direction of its free end is actually restricted to the plane direction perpendicular to the main body of the moving platform 201. Thus, the moving platform 201 can only reciprocate linearly along the normal direction of its platform plane.

[0050] Additionally, see also Figure 3 As shown, to ensure assembly with the moving platform 201, each constraint branch has an interface for mounting and fixing the moving platform 201 at its free end. The specific interface form can be adjusted according to actual needs. From the perspective of practical assembly convenience, each constraint branch needs to have a connecting segment hinged at its free end, and the interface for mounting and fixing the moving platform 201 is set on this connecting segment. This indirectly connects the moving platform 201 and the constraint branch through the connecting segment, facilitating flexible cooperation between the two.

[0051] As mentioned above, both the flapping wing chain 2 and the constraint chain 3 of this invention are assembled by folding after integrated planar processing using SCM technology. Their material is a composite of a middle flexible layer and two rigid layers. The specific materials of the flexible and rigid layers can be optimized according to actual needs. In the embodiments of this invention, the flexible layer is preferably made of polyimide film, and the rigid layer is preferably made of carbon fiber plate. During planar processing using SCM technology, the components can be cut using a laser according to a pre-planned layout design. When there are hinged connections between sub-components within each component, the hinges need to be further cut to maintain the continuity of the middle flexible layer while the rigid layers on both sides are broken and form a toothed interlacing, thereby forming a rotating hinge. Generally, the toothed interlacing is preferably in the form of a wall tooth, that is, each tooth is rectangular in shape.

[0052] like Figure 4 As shown, in the flexible transmission mechanism of the present invention, one end of the crank chain 1 is connected to the moving platform 201, and the other end is connected to the reduction gear set 4 driven by an external motor, thereby converting the continuous rotation input by the external motor into a reciprocating driving force for the moving platform 201 along the normal direction of the platform plane.

[0053] It should be noted that the aforementioned external motor is a micro flapping-wing aircraft component independent of the flexible transmission mechanism of this invention, and can generally be implemented using a servo motor or other micro motors.

[0054] In an embodiment of the present invention, the crank chain 1 includes a crank connecting rod 101, a bearing sleeve 102, a bearing 103, a rudder shaft 104, and a rudder disc 105. Additionally, to facilitate smooth assembly between the various sub-components, a series of shims 106 may be introduced as needed. See also... Figure 4As shown, similar to the flapping wing chain 2 and the constraint chain 3, the crank connecting rod 101 in this embodiment is also integrally machined using SCM technology, and its material is composed of a middle flexible layer and two hard layers. One end of the crank connecting rod 101 is provided with a connecting section for assembling and fixing the moving platform 201 in the form of a hinge connection, and the other end is engaged with the bearing sleeve 102. There is a hinge connection between the connecting section of the crank connecting rod 101 used for assembling and fixing the moving platform 201 and the main body of the crank connecting rod 101. During processing, the middle flexible layer must be kept continuous while the two hard layers on both sides are broken and form a toothed interlacing, thereby forming a rotational hinge. The bearing sleeve 102 is used to install other sub-components at the end of the crank connecting rod 101. Specifically, a bearing 103 is installed in the bearing sleeve 102, and the rudder shaft 104 passes through the bearing 103 to form an interference fit assembly. The rudder disk 105 has shaft holes and gear interfaces side by side, and the bottom of the rudder shaft 104 is interference-fitted into the shaft hole on the rudder disk 105. The shape of the gear interface on the rudder disk 105 matches the output gear of the reduction gear set 4. The output gear of the reduction gear set 4 can be fitted into the gear interface, thereby driving the rudder disk 105 to rotate. When the rudder disk 105 rotates around the output gear of the reduction gear set 4, the rudder shaft 104 will rotate eccentrically, which will cause the crank connecting rod 101 to be driven to form a reciprocating motion. Although the main body of the crank connecting rod 101 is not completely perpendicular to the platform plane of the moving platform 201 during the reciprocating motion, since the main body of the crank connecting rod 101 is engaged and fixed to the moving platform 201 through a hinged connecting section, under the decoupling of this hinge and the constraint of the constraint chain 3, the crank connecting rod 101 will drive the moving platform 201 to reciprocate only along the normal direction of the platform plane, and will not produce horizontal motion in other directions.

[0055] See also Figure 5 As shown, in an embodiment of the present invention, the aforementioned reduction gear set 4 includes a multi-stage gear with cascaded meshing transmission, and each stage of gear adopts a double-layer cascaded gear. The reduction gear set 4 can be assembled and fixed to the frame 5 by means of auxiliary components.

[0056] However, the gear specifications and specific number of stages of the reduction gear set 4 can be adjusted according to actual needs to produce different reduction ratios and adapt to drive motors with different performance. If the size of the reduction gear set changes, the size of other components should be adjusted accordingly to adapt. In the embodiment of the present invention, the reduction gear set 4 includes two stages of gears, referred to as primary gear 401 and secondary gear 402, both of which are plastic double-layer cascaded gears. The plastic double-layer cascaded gears are divided into upper gears and lower gears, and the lower gear of the secondary gear 402 meshes with the upper gear of the primary gear 401. In addition, in order to reliably assemble the two stages of gears onto the frame 5, the present invention also introduces two pivot pins 403, several washers 404, and several mounting bases 405, wherein the two pivot pins 403 are respectively assembled with the primary gear 401 and the secondary gear 402, and the washers 404 and mounting bases 405 are used to assist in the installation. The primary gear 401, secondary gear 402, and shaft pin 403 are all commercially standardized parts; the mounting plate 405 and shim 404 are both laser-cut from carbon fiber plates. The upper gear of the plastic double-layer cascaded gear has the following specifications: module 0.2, number of teeth 10, height 1.2mm, and bore diameter 1.05mm; the lower gear has the following specifications: module 0.2, number of teeth 33, height 0.8mm, and bore diameter 1.05mm. All shaft pins are 1mm diameter, 8mm long, plain shaft pins. These parts are assembled to form a complete two-stage reduction gear set. The reduction gear set can be connected to the frame through the interface reserved on frame 5. However, this reduction gear set 4 is only one implementation in this embodiment; in other embodiments, it can be designed according to actual needs or implemented using complete commercially standardized parts.

[0057] The specific structural form of the frame 5 of this invention can be designed according to actual needs. It mainly provides a mounting carrier for other components, but does not affect the realization of the overall function. However, in the embodiments of this invention, it is recommended that the frame 5 be assembled by plugging carbon fiber components, thereby significantly improving the overall frame rigidity while achieving structural lightweighting, and suppressing system vibrations caused by motor operation and wing flapping.

[0058] Specifically, see [link to relevant document] Figure 6As shown, in an embodiment of the present invention, the frame 5 comprises: a base plate 501, two side ribs 502, two lower crossbeams 503, two upper crossbeams 504, and two side beams 505. Each component is cut from a carbon fiber plate using laser cutting technology. These components are interconnected via pre-reserved interfaces to form the complete frame 5. The frame 5 has pre-reserved interfaces for connection with the flapping wing chain 2 and the reduction gear set 4, and also requires a pre-reserved assembly structure for mounting an external drive motor. In this embodiment, the assembly structure for the external drive motor is constructed using the semi-circular frames in the upper crossbeams 504 and lower crossbeams 503. The motor can then be assembled into the cylindrical assembly space formed by the upper and lower crossbeams. This frame 5 can stably constrain all other components and reduces system vibration caused by the motor's operation through a high-rigidity structural design.

[0059] The above Figure 1 The flexible transmission mechanism of the micro flapping-wing aircraft shown can be pre-fabricated by machining the crank chain 1, flapping-wing chain 2, constraint chain 3, reduction gear set 4, and frame 5, and then performing overall assembly to obtain the complete transmission mechanism. The overall assembly sequence is as follows:

[0060] S1: Assemble and connect the end of the crank connecting rod of crank chain 1 to the moving platform 201 of flapping wing chain 2;

[0061] S2: Assemble and connect the ends of the two constraint branches of constraint chain 3 to the moving platform 201 of flapping wing chain 2 respectively.

[0062] S3: Assemble and connect the fixed platform 301 of the constraint chain 3 with the fixed rod 204 of the flapping wing chain 2;

[0063] S4: Assemble and connect the reduction gear set 4 to the frame 5;

[0064] S5: Assemble and connect the flapping wing chain 2 to the frame 5 through the interface reserved on its fixing rod 204;

[0065] S6: Connect the crank chain 1 to the output gear of the reduction gear set 4 via the gear interface reserved on its rudder 105.

[0066] In an embodiment of the present invention, a flapping wing control method for the flexible transmission mechanism of the above-mentioned micro flapping-wing aircraft is also provided, the specific steps of which are as follows:

[0067] First, the pair of wings 6 of the aircraft are respectively mounted on the two flapping rods 203 of the flapping chain 2; then, the external motor 7 is installed inside the frame 5, and the output end of the motor 7 is connected to the input end of the reduction gear set 4 to form a transmission, forming as shown in the figure. Figure 7 The complete structure of the micro flapping-wing aircraft is shown.

[0068] Then, the external motor 7 drives the reduction gear set 4, which, under the drive of the end of the crank chain 1 and the constraint of the constraint chain 3, drives the moving platform 201 to reciprocate linearly along the normal direction of its platform plane. During the reciprocating motion along the normal direction of the platform plane, the moving platform 201 drives the flapping rod 203 to reciprocate around the hinge between itself and the fixed rod 204 through the transmission link 202, thereby driving the wings 6 installed on the two flapping rods 203 to perform flapping actions.

[0069] During the flapping of wings, Figure 8 and Figure 9 The diagram illustrates the motion relationships of various components during the flapping and opening of a pair of wings 6. The arrows indicate the direction of motion of each component at a local position. It can be seen that as the motor rotates, driving the reduction gear set 4, the reduction gear set 4 drives the crank chain 1 to reciprocate linearly under the constraint of the constraint chain 3. The flapping chain 2 converts this reciprocating linear motion into the reciprocating flapping motion of the wings 6, thus achieving reliable transmission from motor rotation to wing flapping.

[0070] Additionally, it should be noted that the above... Figures 1 to 9 The overall structure and coordination relationship of the flexible transmission mechanism of the micro flapping-wing aircraft are shown, but the detailed parameters can be reasonably adjusted according to the actual processing and application scenarios.

[0071] For example, the lengths of individual links in the crank chain, flapping chain, and constraint chain can be adjusted to output different flapping amplitudes. If the chain dimensions change, the dimensions of other components should be adjusted accordingly to accommodate the change.

[0072] As a preferred embodiment of the present invention, in the crank chain, the bearing is a ball bearing with an inner diameter of 1mm, an outer diameter of 3mm, and a height of 1mm, and the rudder shaft is a smooth shaft pin with a diameter of 1mm and a length of 5mm.

[0073] As a preferred embodiment of the present invention, in the flapping wing chain, the flapping amplitude generated by the flapping rod should be controlled within the range of ±45° to ±60°. Excessive flapping amplitude can easily cause structural anomalies and buckling of flexible hinges.

[0074] As a preferred embodiment of the present invention, in the constraint chain, the two constraint branches should maintain a width that is substantially the same as that of the moving platform in the crank chain. Sufficiently wide constraint branches can provide sufficient torsional stiffness to prevent the moving platform from tilting under the lateral force of the crank chain.

[0075] For example, the material specifications used for parts directly laser-cut from carbon fiber and parts integrally machined using SCM (Surface Mount Technology) can be interchanged. If the material thickness changes, the dimensions of each interface in the mechanism should be adjusted accordingly to accommodate the change.

[0076] As a preferred embodiment of the present invention, all parts (including steering wheel, bearing sleeve, mounting base, gasket, upper crossbeam, lower crossbeam, side beam, side rib, and base plate) cut from carbon fiber plates by laser cutting process in crank chain, frame, and reduction gear set are made of 500um thick twill matte 3k carbon fiber plates, and are stacked according to the thickness required for installation.

[0077] As a preferred embodiment of the present invention, the tiny carbon fiber inserts used to fix the folding points when the flapping chain and constraint chain are folded are all made of 200um thick twill matte 3k carbon fiber plates.

[0078] As a preferred embodiment of the present invention, all parts of the crank chain, flapping chain, and constraint chain manufactured by SCM process are made of carbon fiber plate with a thickness of 150um and polyimide film with a thickness of 50um.

[0079] As a preferred embodiment of the present invention, all interfaces within components and between different components should be connected using an interference fit strategy, and a small amount of 502 glue should be applied to the connection to increase the connection strength.

[0080] The embodiments described above are merely some preferred implementations of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A flexible transmission mechanism for a micro flapping-wing aircraft, characterized in that, It includes a crank chain (1), a flapping chain (2), a constraint chain (3), a reduction gear set (4), and a frame (5); The flapping wing chain (2) includes a moving platform (201) and two sets of rocker mechanisms; each set of rocker mechanisms is formed by a transmission link (202), a flapping rod (203) and a fixed rod (204) connected in sequence by hinges. The two sets of rocker mechanisms are connected to both sides of the moving platform (201) in a mirror symmetrical manner. The transmission link (202) is hinged to the moving platform (201), and the fixed rod (204) is fixedly assembled relative to the frame (5). The flapping rod (203) is provided with an interface for connecting the aircraft wing. During the reciprocating motion of the moving platform (201) along the normal direction of the platform plane, the transmission link (202) drives the flapping rod (203) to rotate back and forth about the hinge between the flapping rod (203) and the fixed rod (204) as the axis of rotation, thereby driving the wing to perform flapping action. The constraint chain (3) includes a fixed platform (301) and two constraint branches connected to both sides of the fixed platform (301). The fixed platform (301) is fixedly assembled on the frame (5) and connected to the moving platform (201) through the two constraint branches, thereby forming a complete Sarrus mechanism. The moving platform (201) is constrained to only make reciprocating linear motion along its platform plane normal. One end of the crank chain (1) is connected to the moving platform (201), and the other end is connected to a reduction gear set (4) driven by an external motor, thereby converting the continuous rotation input by the external motor into a reciprocating driving force for the moving platform (201) along the normal direction of the platform plane.

2. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, In the flapping wing chain (2), the moving platform (201) and the flapping rod (203) are provided with connecting sections on both sides of the main body plane. After the connecting section is bent relative to the main body plane, it is fixed by the first insert piece (205) relative to the main body plane to form a U-shaped structure. The connecting sections on both sides of the moving platform (201) are respectively connected to the two transmission connecting rods (202) in a hinged manner. The connecting sections on both sides of each flapping rod (203) are respectively connected to the transmission connecting rod (202) and the fixed rod (204) in the rocker mechanism in a hinged manner.

3. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, In the constraint chain (3), the fixed platform (301) is engaged and assembled on the two fixed rods (204) on both sides of the flapping wing chain (2); each constraint branch includes two constraint links, and the two constraint links are indirectly connected by a pair of second plug-in pieces (304) to form a hinge-type connection. The axis of the hinge is parallel to the platform plane of the moving platform (201). Under the action of external force, the distance between the fixed end and the free end of the constraint link is adjusted by adjusting the opening angle. The free end of each constraint branch is provided with an interface for assembling and fixing the moving platform (201).

4. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, The crank chain (1) includes a crank connecting rod (101), a bearing sleeve (102), a bearing (103), a rudder shaft (104), and a rudder disc (105). One end of the crank connecting rod (101) is provided with a connecting section for assembling and fixing the moving platform (201) in the form of a hinge connection, and the other end is engaged with the bearing sleeve (102). The bearing sleeve (102) is equipped with the assembly of the bearing (103) and the rudder shaft (104). The rudder disc (105) has a shaft hole and a gear interface side by side. The bottom of the rudder shaft (104) is assembled in the shaft hole. The output gear of the reduction gear set (4) can be assembled into the gear interface to drive the rudder disc (105) to rotate, and then drive the moving platform (201) to reciprocate along the normal direction of the platform plane through the crank connecting rod (101).

5. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 3, characterized in that, Both the flapping wing chain (2) and the constraint chain (3) are assembled by folding after being integrally machined by SCM process. Their materials are composed of a middle flexible layer and two hard layers. When there is a hinge connection between the sub-components inside each component, the middle flexible layer needs to be continuous while the two hard layers are broken and form a toothed interlacing to form a rotating hinge.

6. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 4, characterized in that, The crank connecting rod (101) is integrally machined by SCM process, and there is a hinge connection between the connecting section of the crank connecting rod (101) used to assemble and fix the moving platform (201) and the main body. During processing, the middle flexible layer must be kept continuous while the hard layers on both sides are broken and form a toothed interlacing, thereby forming a rotating hinge.

7. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 5 or 6, characterized in that, In the SCM process, the flexible layer is made of polyimide film, and the rigid layer is made of carbon fiber plate.

8. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, The reduction gear set (4) includes a multi-stage gear with cascaded meshing transmission, and each stage of gear adopts a double-layer cascaded gear; the reduction gear set (4) is assembled and fixed on the frame (5) by auxiliary parts.

9. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, The frame (5) is assembled by plugging carbon fiber components, and has reserved assembly structures for the drive motor, as well as assembly slots for the flapping chain (2) and the reduction gear set (4).

10. A flapping wing control method for a flexible transmission mechanism of a micro flapping-wing aircraft as described in claim 1, characterized in that, The pair of wings of the aircraft are respectively mounted on the two flapping rods (203) of the flapping chain (2); then the external motor drives the reduction gear set (4), and under the drive of the end of the crank chain (1) and the constraint of the constraint chain (3), the moving platform (201) is driven to reciprocate linearly along the normal direction of its platform plane; during the reciprocating motion along the normal direction of the platform plane, the moving platform (201) drives the flapping rod (203) to reciprocate around the hinge between itself and the fixed rod (204) through the transmission link (202), thereby driving the wings mounted on the two flapping rods (203) to perform flapping actions.

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