A flapping-wing aircraft

Abstract

This invention discloses a flapping-wing aircraft, relating to the field of biomimetic flapping-wing technology. It includes a frame, a drive mechanism, a crank transmission mechanism, a multi-link transmission mechanism, and flapping wings. Two multi-link transmission mechanisms and two flapping wings are symmetrically arranged on both sides of the frame. The drive mechanism body is fixedly connected to the frame, and the output shaft of the drive mechanism is fixedly connected to the input end of the crank transmission mechanism. The output end of the crank transmission mechanism is connected to the input ends of the two multi-link transmission mechanisms. The end of each flapping wing closest to the frame is hinged to the frame, and each flapping wing is also hinged to the output end of the multi-link transmission mechanism. The extreme position angle of the multi-link transmission mechanism is greater than 0°, allowing both flapping wings to rotate with only one drive mechanism. The greater than 0° extreme position angle of the multi-link transmission mechanism improves the aerodynamic efficiency and flight attitude control stability of the flapping-wing aircraft, meeting the performance requirements of practical application scenarios.

Description

Technical Field

[0001] This invention relates to the field of biomimetic flapping wing technology, and in particular to a flapping wing aircraft. Background Technology

[0002] As a type of biomimetic aircraft, flapping-wing aircraft are inspired by the flight movements of birds and insects in nature. Their adaptability in confined spaces and complex environments far exceeds that of traditional aircraft. Among them, butterfly-inspired flapping-wing aircraft have unique application value in low-altitude, low-speed detection and biomimetic demonstrations due to their low flapping frequency and large wingspan. Currently, the flapping mechanism of traditional flapping-wing aircraft mostly uses the coordinated control of dual servo motors to drive the wings to complete periodic up-and-down flapping movements to achieve flight.

[0003] However, the aforementioned traditional flapping-wing mechanism design has the following two problems: 1. This type of structure requires dual servos as drive components. The dual servos not only increase the overall weight of the flapping-wing mechanism, but also hinder the lightweight design of flapping-wing aircraft; 2. This type of structure can often only achieve symmetrical periodic flapping of the wing, and cannot effectively simulate the asymmetrical flapping characteristics of butterflies in real flight, which are characterized by "fast upstroke and slow downstroke." These two technical defects interact, ultimately leading to a significant decrease in the aerodynamic efficiency of traditional flapping-wing aircraft and poor flight attitude control stability, failing to meet the performance requirements of flapping-wing aircraft in practical application scenarios. Summary of the Invention

[0004] The purpose of this invention is to provide a flapping-wing aircraft to solve the problems existing in the prior art and meet the performance requirements of flapping-wing aircraft in practical application scenarios.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides a flapping-wing aircraft, comprising: a frame, a drive mechanism, a crank transmission mechanism, a multi-link transmission mechanism, and flapping wings. The multi-link transmission mechanism and the flapping wings are both present in pairs and symmetrically arranged on both sides of the frame. The body of the drive mechanism is fixedly connected to the frame, and the output shaft of the drive mechanism is fixedly connected to the input end of the crank transmission mechanism. The output end of the crank transmission mechanism is drively connected to the input ends of the two multi-link transmission mechanisms. The end of each flapping wing closest to the frame is hinged to the frame, and each flapping wing is also hinged to the output end of each multi-link transmission mechanism. The extreme position angle of the multi-link transmission mechanism is greater than 0. The drive mechanism can simultaneously drive the input ends of the two multi-link transmission mechanisms to reciprocate through the crank transmission mechanism, and then, through the output ends of the two multi-link transmission mechanisms, drive the ends of the two flapping wings furthest from the frame to reciprocate around the ends closest to the frame.

[0006] In some embodiments, the crank transmission mechanism includes a drive gear, a first follower gear, and a second follower gear. The output shaft of the drive mechanism is fixedly connected to the axis of the drive gear. The first follower gear and the second follower gear are symmetrically arranged on both sides of the frame. The first follower gear meshes with the drive gear. The end face of the first follower gear is hinged to the input end of one of the multi-link transmission mechanisms. The second follower gear meshes with the first follower gear. The end face of the second follower gear is hinged to the input end of another multi-link transmission mechanism. The drive gear can drive the first follower gear and the second follower gear to rotate synchronously in opposite directions.

[0007] In some embodiments, the multi-link transmission mechanism includes a first link, a second link, and a third link. The end of the first link near the frame is the input end of the multi-link transmission mechanism and is hinged to the end face of the first follower gear or the end face of the second follower gear. The other end of the first link is hinged to one end of the second link, and the other end of the second link serves as the output end of the multi-link transmission mechanism and is hinged to one of the flapping wings. One end of the third link is hinged to the frame, and the other end is hinged to both ends of the second link. When the first link swings with the first or second follower gear hinged to it, it can drive the third link to reciprocate around the hinge point with the frame, while simultaneously causing the end of the second link connected to the flapping wing to reciprocate around the hinge point between the third link and the second link.

[0008] In some embodiments, the flapping wing includes a fourth link, the end of which near the frame is hinged to the frame, and the other end of the second link serves as the output end of the multi-link transmission mechanism, and is hinged to both ends of the fourth link.

[0009] In some embodiments, the flapping wing further includes a flapping wing frame and a wing membrane, the flapping wing frame being fixedly connected to the fourth link, and the edge of the wing membrane being fixedly connected to the flapping wing frame.

[0010] In some embodiments, the diameter of the first follower gear and the number of teeth of the second follower gear are both larger than the number of teeth of the drive gear, so that the rotational angular velocity of the first follower gear and the rotational angular velocity of the second follower gear are smaller than the rotational angular velocity of the drive gear.

[0011] In some embodiments, the frame is 3D printed from laser-printed resin material.

[0012] In some embodiments, both the crank drive mechanism and the multi-link drive mechanism are made of carbon fiber.

[0013] In some embodiments, the frame has a mounting section in the middle for connecting external transport objects.

[0014] In some embodiments, the drive mechanism includes a drive motor.

[0015] The present invention achieves the following technical effects compared to the prior art: This invention discloses a flapping-wing aircraft. A crank-driven transmission mechanism simultaneously drives the input ends of two multi-link transmission mechanisms to reciprocate. The output ends of these two multi-link transmission mechanisms then drive the ends of two flapping wings furthest from the frame to reciprocate around the ends closest to the frame. This transforms the composite motion of the multi-link transmission mechanisms in a plane into the periodic reciprocating flapping motion of the flapping wings. Firstly, a single drive mechanism is sufficient to drive the ends of the two flapping wings furthest from the frame to rotate around the ends closest to the frame, eliminating the need for a dual-motor drive design and reducing the overall weight of the flapping-wing aircraft, making it lighter. Secondly, the extreme position angle of the multi-link transmission mechanisms is greater than 0, giving them a quick-return characteristic. This allows the flapping wings to simulate the asymmetrical flapping characteristics of a butterfly's flight—a fast upstroke and a slow downstroke. Through these two aspects, the aerodynamic efficiency and flight attitude control stability of the flapping-wing aircraft are improved, meeting the performance requirements of practical application scenarios. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the flapping-wing aircraft structure in some embodiments of the present invention; Figure 2 This is a simplified structural diagram of a flapping-wing aircraft in some embodiments of the present invention; Figure 3 Kinematic modeling of flapping-wing aircraft in some embodiments of the present invention; Figure 4 This is a schematic diagram of the flapping-wing aircraft from another perspective in some embodiments of the present invention; Figure 5 This is a diagram showing the velocity variation in the X direction of the end of the flapping wing furthest from the frame in some embodiments of the present invention; Figure 6 This is a diagram showing the X-direction acceleration variation at the end of the flapping wing furthest from the frame in some embodiments of the present invention; Figure 7This is a diagram showing the velocity variation in the Z-direction at the end of the flapping wing furthest from the frame in some embodiments of the present invention; Figure 8 This is a diagram showing the Z-direction acceleration variation at the end of the flapping wing furthest from the frame in some embodiments of the present invention; Figure 9 This is a diagram showing the variation of the flapping angle of the flapping wing in some embodiments of the present invention; Figure 10 The XZt three-dimensional spatiotemporal trajectory motion curve of the end of the flapping wing away from the frame in some embodiments of the present invention; In the diagram: 1-Frame; 2-Drive mechanism; 3-Crank transmission mechanism; 31-Drive gear; 32-First follower gear; 33-Second follower gear; 4-Multi-link transmission mechanism; 41-First link; 42-Second link; 43-Third link; 5-Flapping wing; 51-Fourth link; 6-Mounting part. Detailed Implementation

[0018] 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.

[0019] The purpose of this invention is to provide a flapping-wing aircraft to solve the problems existing in the prior art and meet the performance requirements of flapping-wing aircraft in practical application scenarios.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] This invention provides a flapping-wing aircraft, such as Figure 1As shown, the system includes: a frame 1, a drive mechanism 2, a crank transmission mechanism 3, a multi-link transmission mechanism 4, and flapping wings 5. There are two multi-link transmission mechanisms 4 and two flapping wings 5, symmetrically arranged on both sides of the frame 1. The drive mechanism 2 is fixedly connected to the frame 1. The output shaft of the drive mechanism 2 is fixedly connected to the input end of the crank transmission mechanism 3. The output end of the crank transmission mechanism 3 is connected to the input ends of the two multi-link transmission mechanisms 4. The end of each flapping wing 5 closest to the frame 1 is hinged to the frame 1. Each flapping wing 5 is also hinged to the output end of the multi-link transmission mechanism 4. The extreme position angle of the multi-link transmission mechanism 4 is greater than 0. The drive mechanism 2 can simultaneously drive the input ends of the two multi-link transmission mechanisms 4 to reciprocate through the crank transmission mechanism 3, and then drive the two flapping wings respectively through the output ends of the two multi-link transmission mechanisms 4. The end of the flapping wing 5 furthest from the frame 1 reciprocates around the end closest to the frame 1, thereby transforming the compound motion of the multi-link transmission mechanism 4 in the plane into the periodic reciprocating flapping motion of the flapping wing 5. On the one hand, only one drive mechanism 2 is needed to drive the ends of the two flapping wings 5 ​​furthest from the frame 1 to rotate around the ends closest to the frame 1, thus eliminating the need for a dual-motor drive design, reducing the overall weight of the flapping wing aircraft, and making it lighter. On the other hand, because the extreme position angle of the multi-link transmission mechanism 4 is greater than 0, the multi-link transmission mechanism 4 has a quick-return characteristic, which allows the flapping wing 5 to simulate the asymmetrical flapping characteristics of "fast upstroke and slow downstroke" in the real flight of a butterfly. Through the above two aspects, the aerodynamic efficiency and flight attitude control stability of the flapping wing aircraft are improved, meeting the performance requirements of flapping wing aircraft in actual application scenarios.

[0022] In some embodiments, the crank transmission mechanism 3 includes a drive gear 31, a first follower gear 32, and a second follower gear 33. The output shaft of the drive mechanism 2 is fixedly connected to the axis of the drive gear 31. The first follower gear 32 and the second follower gear 33 are symmetrically arranged on both sides of the frame 1. The first follower gear 32 meshes with the drive gear 31, and the end face of the first follower gear 32 is hinged to the input end of a multi-link transmission mechanism 4. The second follower gear 33 meshes with the first follower gear 32, and the end face of the second follower gear 33 is hinged to the input end of another multi-link transmission mechanism 4. The drive gear 31 can drive the first follower gear 32 and the second follower gear 33 to rotate synchronously in opposite directions. This allows the two flapping wings 5 ​​to rotate around the end closest to the frame 1 from the end away from the frame 1 using only one drive mechanism 2. This enables the flapping wings 5 ​​on both sides of the frame 1 to perform periodic reciprocating flapping motions synchronously, ensuring the phase consistency of the flapping wings 5 ​​on both sides. This eliminates the need for a dual-motor drive design, reduces the overall weight of the flapping wing aircraft, making it lighter. Furthermore, the gear meshing design ensures the stability of the crank transmission mechanism 3 during operation.

[0023] In some embodiments, the multi-link transmission mechanism 4 includes a first link 41, a second link 42, and a third link 43. The end of the first link 41 near the frame 1 is the input end of the multi-link transmission mechanism 4, which is hinged to the end face of the first follower gear 32 or the end face of the second follower gear 33. The other end of the first link 41 is hinged to one end of the second link 42. The other end of the second link 42 serves as the output end of the multi-link transmission mechanism 4 and is hinged to a flapping wing 5. One end of the third link 43 is hinged to the frame 1, and the other end is hinged to both ends of the second link 42. When the first link 41 swings with the first follower gear 32 or the second follower gear 33 hinged to it, it can drive the third link 43 to reciprocate around the hinge point with the frame 1. At the same time, the end of the second link 42 connected to the flapping wing 5 reciprocates around the hinge point between the third link 43 and the second link 42, thereby causing the flapping wing 5 to flap periodically.

[0024] In some embodiments, the flapping wing 5 includes a fourth link 51, the end of the fourth link 51 near the frame 1 is hinged to the frame 1, and the other end of the second link 42 serves as the output end of the multi-link transmission mechanism 4 and is hinged to both ends of the fourth link 51. When the first link 41 swings with the first follower gear 32 or the second follower gear 33 hinged to it, the fourth link 51 can perform a periodic reciprocating flapping motion around the end of it hinged to the frame 1.

[0025] In some embodiments, the flapping wing 5 also includes a flapping wing frame and a wing membrane. The flapping wing frame is fixedly connected to the fourth link 51, and the edge of the wing membrane is fixedly connected to the flapping wing frame to form the flapping wing 5, which can achieve powered flight through interaction with the air.

[0026] In some embodiments, the diameter of the first follower gear 32 and the number of teeth of the second follower gear 33 are both larger than the number of teeth of the drive gear 31, so that the rotational angular velocity of the first follower gear 32 and the rotational angular velocity of the second follower gear 33 are smaller than the rotational angular velocity of the drive gear 31, thereby reducing the rotational speed and amplifying the torque, and improving the control accuracy and stability of the periodic reciprocating flapping motion of the flapping wing 5.

[0027] In some embodiments, the frame 1 is 3D printed using laser-printed resin. In some embodiments, both the crank drive mechanism 3 and the multi-link drive mechanism 4 are made of carbon fiber. In some embodiments, a mounting section 6 is provided in the middle of the frame 1 for attaching an external transport object, which can be installed using bolts or adhesive. In some embodiments, the drive mechanism 2 includes a drive motor, specifically, the rated speed of the drive motor is 350 rpm.

[0028] Theoretical verification of the flapping-wing aircraft provided by this invention: Figure 2The kinematic modeling diagram of the flapping-wing aircraft shows the complete structural path of drive, transmission, and output. The drive mechanism drives the first follower gear on the left to move around point A with an angular velocity... The rotation, in turn, transmits the power through the multi-link transmission mechanism to the fourth link EF in the flapping wing to achieve the upward and downward flapping actions; the multi-link transmission mechanisms on both sides and the flapping wings are symmetrical about the key point of AN, and their working principles are completely the same.

[0029] The fourth link EF is hinged to the frame at the end closest to it. Assume the lengths of a series of links in the flapping-wing aircraft are as follows: Figure 3 As shown, if the coordinates of hinge points A, G, and F are fixed, then in In the middle, driven by the angle The coordinates of point B can be obtained from the relevant physical quantities: According to the formula for distance between two points: We can obtain the result using the Law of Cosines (recorded as) )and (recorded as) ): Then in We can obtain the answer by using the Law of Cosines again. (recorded as) ): The azimuth angle of the third link DG can be obtained. And the coordinates of the critical node D: The position of node D is determined, and F is a fixed point. Draw an auxiliary line connecting D and F to obtain DF and the auxiliary angle. (Angle between DF and the horizontal line): Solve using the Law of Cosines ( ): This yields the azimuth angle of the fourth link EF. And the trajectory equation of the terminal E: According to the three-center theorem, the absolute instantaneous center of component BD is... It is located at the intersection of the extended line of crank AB formed by the first follower gear and the extended line of third connecting rod DG. From geometric relationships, we can obtain: Since B and D both belong to component BD, their positions around the instantaneous center are... Since it rotates, the corresponding angular velocity is: Then the linear velocity of node D can be obtained: Based on the instantaneous velocity ratio relationship: Solving the above equations simultaneously, we can obtain the instantaneous linear velocity of the output E with respect to the input. The analytical expression: This velocity expression reflects the variation of the flapping wing's velocity at different positions and directly affects the flapping wing's frequency and beat structure.

[0030] Another significant kinematic characteristic of this flapping-wing aircraft is its quick-return characteristic. Due to the asymmetry of the eccentric wheel trajectory in the crank-connecting rod mechanism composed of the first connecting rod and the first follower gear, the extreme position angle is greater than 0, causing the time experienced by the fourth connecting rod EF in the upstroke to be significantly shorter than that in the downstroke. This achieves the asymmetry of the flapping-wing rhythm, and its quick-return ratio is defined as: This characteristic allows the flapping wings to exert force slowly during the descent phase and quickly return to their original position during the upward phase, which is consistent with the aerodynamic characteristics of real butterflies in flight, using descent to accelerate and upward to reduce drag.

[0031] In summary, the flapping-wing aircraft, composed of a frame, drive mechanism, crank transmission mechanism, multi-link transmission mechanism, and flapping wings, can not only achieve continuous control of the biomimetic flapping wing angle, but also has adjustable beat ratio, drive speed, and output trajectory range. The overall structure is compact and the motion is stable, providing theoretical basis and geometric support for subsequent motion simulation and performance analysis.

[0032] Regarding the motion simulation and performance analysis of the flapping-wing aircraft provided by this invention: 1. Simulation Modeling and Parameter Setting To verify the motion performance of the flapping-wing aircraft proposed in this study in a dynamic operating environment, a three-dimensional multibody kinematics simulation model was established using the ADAMS software platform, aiming to simulate the motion characteristics of the structure.

[0033] First, establish the operational coordinate framework, such as Figure 4As shown. This coordinate frame serves as a standardized reference system for subsequent acquisition of displacement, velocity, and acceleration.

[0034] In the simulation model, the frame is first fixedly connected to the ground via a fixed joint, serving as the fixed reference for the entire flapping-wing aircraft. Then, the first follower gear on the left side is also hinged to the frame via a revolute joint to provide rotational freedom. The input end of the multi-link transmission mechanism is hinged to the end face of the first follower gear via a revolute joint. One end of the flapping wing is hinged to the frame via a revolute joint, and the two ends of the flapping wing are hinged to the output end of the multi-link transmission mechanism to achieve periodic flapping of the flapping wing. The structure on the right side adopts a completely mirror-symmetrical configuration, forming a dual-wing synchronous drive architecture.

[0035] 2. Analysis of velocity and acceleration characteristics (1) Quick return characteristic analysis The flapping wing speed variation curve is as follows Figure 5 and 7 As shown in the simulation, the flapping wing's speed is significantly higher during the downward flapping phase than during the upward flapping phase, exhibiting obvious asymmetric motion characteristics.

[0036] The main purpose of introducing quick-return characteristics is to achieve rhythm modulation of flapping wings through the kinematic characteristics of the mechanism, thereby reducing the dependence on complex electronic control strategies and multi-actuator drives. This method of achieving motion rhythm regulation based on mechanical structure is beneficial to reducing the complexity and weight of flapping wing aircraft structure, and improving the stability and lightweight of flapping wing aircraft structure.

[0037] according to Figure 5 and 7 The velocity-time curve shown, obtained from formula (15), indicates that the beat ratio of the flapping wing mechanism is approximately 1.57, demonstrating a significant quick-return effect within one flapping cycle. In real butterflies in free flight, the beat ratio is generally distributed between 1.5 and 1.5. Between 2.5 and 2.5, the flapping-wing aircraft provided in this application maintains consistency with this range in terms of quick-return speed ratio and motion rhythm, indicating that the obtained quick-return characteristics have a certain degree of biological rationality and biomimetic feasibility.

[0038] (2) Motion stability analysis The flapping wing velocity curve is continuous and smooth overall, without any sudden changes or unreasonable oscillations, indicating that the motion transmission process of the flapping wing aircraft is stable and reliable.

[0039] The main purpose of conducting motion stability analysis is to evaluate the impact of the mechanism on the structural impact and motor load during periodic flapping. Stable speed and acceleration changes help reduce the inertial impact of the mechanism at the moment of reversal, reduce the dynamic load fluctuation at the joints, thereby reducing the instantaneous torque demand of the drive motor, which is of great significance for the reliable operation of flapping-wing aircraft.

[0040] from Figure 6 and 8 As shown in the acceleration curve, the flapping wing acceleration exhibits a clear periodicity throughout the entire motion cycle, with its period consistent with the flapping wing motion cycle, corresponding to the periodic reciprocating motion process of the mechanism. The acceleration peak is mainly concentrated at the reversal position of the flapping wing's up-and-down flapping motion, while the acceleration changes relatively smoothly in other time periods, without any abnormal peaks or irregular fluctuations.

[0041] Because the flapping wings need to reverse their velocity direction during this phase, local peaks in acceleration are inevitable. This phenomenon is a typical kinematic characteristic of the mechanism, rather than being caused by structural instability or transmission discontinuity. In addition, because the mechanism uses a continuously rotating drive motor as input and achieves motion conversion through a multi-link transmission mechanism, intermittent transmission or rigid collisions are avoided. Therefore, the amplitude of the acceleration peak is effectively suppressed, and the overall motion process maintains good smoothness.

[0042] 3. Analysis of flapping angle like Figure 9 As shown, the flapping wing exhibits obvious periodic variation characteristics and good repeatability within a complete motion cycle, indicating that the proposed flapping wing aircraft can achieve continuous flapping motion.

[0043] The flapping angle changes in a basically symmetrical manner during the upward and downward flapping phases, with the maximum flapping angle being approximately +65° and the minimum flapping angle being approximately -50°. The overall flapping amplitude is similar to the range of wing movement during natural butterfly flight, demonstrating good biomimetic characteristics.

[0044] The main purpose of setting up the flapping angle analysis is to verify whether the flapping wing aircraft can meet the basic requirements of the biomimetic butterfly for the range of flapping angles during flight. In nature, the flapping angles of most butterflies are usually distributed in the range of approximately Within a certain range, the angle change during the flapping process exhibits obvious periodic characteristics.

[0045] 4. Displacement Characteristics and Trajectory Analysis Unlike the aforementioned flapping wing angle, velocity curve, and acceleration curve, the XZt three-dimensional trajectory re-verifies the overall motion behavior of the flapping-wing aircraft from a spatial dimension. Figure 10 It can be seen that the spatial motion trajectories of key points at the wingtip are highly overlapping in multiple consecutive flapping cycles, and are only distributed in translational distribution on the time axis. This indicates that the multi-link transmission mechanism can maintain good spatial motion consistency under the drive of a single drive mechanism.

[0046] Furthermore, the X–Z–t three-dimensional trajectory clearly demonstrates the continuous evolution of the spatial position of the flapping wing's end away from the frame during the time progression, indicating that the mechanism has a good kinematic coupling relationship between the time and spatial domains. This result verifies that it is feasible at the kinematic level to realize complex flapping wing spatial motion through a multi-link transmission mechanism under single-drive mechanism input conditions. At the same time, the integrity and path continuity of the spatial trajectory of the flapping wing's end away from the frame within a single flapping wing cycle show that its motion trajectory connects naturally between the starting and ending positions without obvious jumps or unreasonable deviations, indicating that the mechanism has good spatial motion coordination within a motion cycle. Combined with the analysis of the change law of the trajectory of the flapping wing's end away from the frame during the time progression, it can be seen that the flapping wing mechanism maintains a relatively stable spatiotemporal correspondence during the motion, further demonstrating the kinematic rationality of the disclosed flapping wing aircraft.

[0047] It should be noted that this three-dimensional spatiotemporal trajectory analysis is not a simple repetition of the aforementioned angle, velocity, and acceleration results, but rather a supplementary verification of the simulation results from the perspective of the overall spatial motion of the mechanism.

[0048] 5. Overall Simulation Analysis Based on the above simulation results, the proposed flapping-wing aircraft can achieve stable, continuous, and biomimetic flapping-wing motion at the kinematic level. Under the input conditions of a single drive mechanism, the overall operation of the mechanism is smooth, and there is no motion interference or unexpected constraint conflict between the components. This indicates that the established multibody kinematic model and its constraint relationship are reasonable and effective. The simulation results verify the kinematic feasibility and stability of the proposed flapping-wing aircraft from multiple levels, including velocity, acceleration, flapping angle, and spatial trajectory. The flapping-wing aircraft utilizes the quick-return characteristics of the crank-connecting rod mechanism composed of the first connecting rod and the first follower gear to achieve asymmetric flapping-wing motion with biomimetic rhythmic characteristics at the kinematic level.

[0049] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A flapping-wing aircraft, characterized in that: include: The system comprises a frame, a drive mechanism, a crank transmission mechanism, a multi-link transmission mechanism, and flapping wings. Two multi-link transmission mechanisms and two flapping wings are symmetrically arranged on both sides of the frame. The drive mechanism is fixedly connected to the frame, and its output shaft is fixedly connected to the input end of the crank transmission mechanism. The output end of the crank transmission mechanism is connected to the input ends of the two multi-link transmission mechanisms. The end of each flapping wing closest to the frame is hinged to the frame, and each flapping wing is also hinged to the output end of each multi-link transmission mechanism. The extreme position angle of the multi-link transmission mechanism is greater than 0. The drive mechanism can simultaneously drive the input ends of the two multi-link transmission mechanisms to reciprocate through the crank transmission mechanism, and then, through the output ends of the two multi-link transmission mechanisms, drive the ends of the two flapping wings furthest from the frame to reciprocate around the ends closest to the frame.

2. The flapping-wing aircraft according to claim 1, characterized in that: The crank transmission mechanism includes a drive gear, a first follower gear, and a second follower gear. The output shaft of the drive mechanism is fixedly connected to the axis of the drive gear. The first follower gear and the second follower gear are symmetrically arranged on both sides of the frame. The first follower gear meshes with the drive gear. The end face of the first follower gear is hinged to the input end of one of the multi-link transmission mechanisms. The second follower gear meshes with the first follower gear. The end face of the second follower gear is hinged to the input end of another multi-link transmission mechanism. The drive gear can drive the first follower gear and the second follower gear to rotate synchronously in opposite directions.

3. The flapping-wing aircraft according to claim 2, characterized in that: The multi-link transmission mechanism includes a first link, a second link, and a third link. The end of the first link near the frame is the input end of the multi-link transmission mechanism, which is hinged to the end face of the first follower gear or the end face of the second follower gear. The other end of the first link is hinged to one end of the second link. The other end of the second link serves as the output end of the multi-link transmission mechanism and is hinged to one of the flapping wings. One end of the third link is hinged to the frame, and the other end is hinged to both ends of the second link. When the first link swings with the first or second follower gear hinged to it, it can drive the third link to reciprocate around the hinge point with the frame, while simultaneously causing the end of the second link connected to the flapping wing to reciprocate around the hinge point between the third link and the second link.

4. The flapping-wing aircraft according to claim 3, characterized in that: The flapping wing includes a fourth link, the end of which near the frame is hinged to the frame, and the other end of the second link serves as the output end of the multi-link transmission mechanism, which is hinged to both ends of the fourth link.

5. The flapping-wing aircraft according to claim 4, characterized in that: The flapping wing also includes a flapping wing frame and a wing membrane. The flapping wing frame is fixedly connected to the fourth link, and the edge of the wing membrane is fixedly connected to the flapping wing frame.

6. The flapping-wing aircraft according to claim 2, characterized in that: The diameter of the first follower gear and the number of teeth of the second follower gear are both larger than the number of teeth of the drive gear, so that the rotational angular velocity of the first follower gear and the rotational angular velocity of the second follower gear are smaller than the rotational angular velocity of the drive gear.

7. The flapping-wing aircraft according to claim 1, characterized in that: The frame is made of laser-printed resin material using 3D printing.

8. The flapping-wing aircraft according to claim 1, characterized in that: Both the crank transmission mechanism and the multi-link transmission mechanism are made of carbon fiber.

9. The flapping-wing aircraft according to claim 1, characterized in that: The frame has a mounting section in the middle, which is used to connect external transport objects.

10. The flapping-wing aircraft according to claim 1, characterized in that: The drive mechanism includes a drive motor.

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