A variable-amplitude flapping wing driving mechanism with quick-return motion characteristics

Abstract

This invention provides a flapping wing drive mechanism with quick-return motion characteristics and variable amplitude, including a motor, a main rod, a first slider, an actuator rod, a second slider, a fixed rod, and a connecting rod. The motor is located at the bottom of the main rod and offset along the central axis of the main rod. The first slider is slidably mounted on the main rod and is connected to the output shaft of the motor through a drive component. The fixed rod is fixed to the main rod and located above the first slider. Two actuator rods are provided, each rotatably connected to the first slider. Two second sliders are provided, each slidably connected to a corresponding actuator rod. Two connecting rods are provided, with the lower end of each connecting rod rotatably connected to a corresponding second slider and the middle part of each connecting rod rotatably connected to the corresponding end of the fixed rod.

Description

Technical Field

[0001] This invention relates to a flapping-wing aircraft drive mechanism, and more particularly to a flapping-wing drive mechanism with rapid return motion characteristics and variable amplitude. Background Technology

[0002] Flapping-wing aircraft generate lift and thrust by mimicking the reciprocating flapping of biological wings, exhibiting higher aerodynamic efficiency and maneuverability compared to fixed-wing and rotary-wing aircraft. To simulate the variable flight attitudes of organisms, the performance of the flapping-wing drive mechanism directly determines the aircraft's environmental adaptability. Existing flapping-wing drive mechanisms mostly employ single-degree-of-freedom crank-rocker or crank-slider mechanisms. While simple in structure, their flapping amplitude is locked after the mechanism is manufactured, making flexible adjustment during flight or between missions impossible. Patent CN112078790A discloses a flapping-wing drive device and aircraft, employing a centered crank-slider structure where the crank's rotation center is entirely located on the extension line of the translational trajectory of the translational drive component. Patent CN102285453A discloses a continuously variable amplitude flapping-wing drive mechanism, adjusting the flapping amplitude by changing the eccentricity of the preceding input stage. Although some existing solutions attempt to introduce a variable amplitude mechanism, they often have the following problems: (1) Lack of optimization of dynamic characteristics. Existing variable amplitude mechanisms mostly focus on the change of geometric stroke and ignore the consideration of the quick return characteristics during flapping wing motion. In actual flight, a single simple harmonic flapping motion is difficult to achieve the optimal ratio of aerodynamic output in the down-fluttering and up-fluttering phases, which limits the lift efficiency of the aircraft in complex environments; (2) In order to achieve amplitude adjustment, planetary gears, movable internal gear rings, servo motors and heavy precision metal parts are introduced. This multi-stage gear overlap design makes the mechanism bulky and heavy. Moreover, the rotational inertia generated by the gear train at high speed is extremely large, which seriously compresses the already precious payload space of flapping wing UAVs. In addition, existing luffing mechanisms have the following drawbacks: the pressure angle of the adjustment transmission chain fluctuates violently, which easily leads to mechanism self-locking. Existing luffing schemes usually apply the adjustment force directly to the actuator, which causes the pressure angle between the adjustment component and the actuator to change violently and non-linearly with displacement during the adjustment process. This not only causes a sharp drop in transmission efficiency during the adjustment process, but also easily leads to mechanical self-locking (jamming) when approaching the limit amplitude, which seriously affects the reliability and stability of the adjustment. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a flapping wing drive mechanism with rapid return motion characteristics and variable amplitude, comprising a motor, a main rod, a first slider, an actuator rod, a second slider, a fixed rod, and a connecting rod. The motor is located at the bottom of the main rod and offset along the central axis of the main rod. The first slider is slidably mounted on the main rod and is connected to the motor's rotary output shaft via a drive component. The fixed rod is fixed to the main rod and located above the first slider. Two actuator rods are provided, each rotatably connected to the first slider. Two second sliders are provided, each slidably connected to a corresponding actuator rod. Two connecting rods are provided, with the lower end of each connecting rod rotatably connected to a corresponding second slider and the middle portion of each connecting rod rotatably connected to the corresponding end of the fixed rod.

[0004] Furthermore, it also includes a movable rod. The movable rod is slidably mounted on the main rod and located above the fixed rod in the middle. Straight guide grooves are provided at both ends of the movable rod along its own axis. The upper end of the connecting rod is set in the corresponding guide groove and slides in the guide groove.

[0005] Furthermore, an offset distance is provided between the motor output shaft and the central axis of the main rod.

[0006] Furthermore, the driving component includes a crank and a connecting rod. One end of the crank is fixedly connected to the output shaft of the motor, one end of the connecting rod is hinged to the other end of the crank, and the other end of the connecting rod is hinged to the first slider.

[0007] Furthermore, the two actuators are symmetrically distributed along the central axis of the main rod, and the two second sliders are symmetrically distributed along the central axis of the main rod.

[0008] Furthermore, a friction-reducing layer or rolling bearing is provided between the first slider and the main rod, and between the second slider and the actuator rod.

[0009] Furthermore, the cross-section of the main rod is polygonal to restrict the rotation of the first slider and the movable crossbar around the axis of the main rod.

[0010] Compared with the prior art, the present invention has the following advantages: (1) An offset distance is designed between the output axis of the motor and the central axis of the main rod, and an offset crank-slider mechanism is constructed to generate an asymmetric reciprocating linear displacement, so that the flapping wing has the characteristics of "fast descent and slow rebound"; in real biomimetic flight (such as bird or insect flight), the main lift is often generated by the descent action. The offset crank-slider mechanism makes the flapping wing faster in the descent stage, thereby optimizing the velocity field in the descent stage; (2) The drive, transmission and amplitude conversion components are highly integrated on the main rod axis, which greatly reduces the size of the mechanism and reduces the rotational inertia of the system, which is conducive to the precise control of the aircraft's center of gravity; (3) The lever transmission mechanism formed by the connecting rod smoothly maps the adjustment displacement to the execution module, improves the pressure angle in the amplitude conversion process, avoids adjustment self-locking, and improves the reliability of operation.

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

[0012] Figure 1 This is an axonometric schematic diagram provided for an embodiment of the present invention.

[0013] Figure 2 This is a rear view diagram provided for an embodiment of the present invention.

[0014] Reference numerals: frame 10, main rod 11, mounting base 12, drive module 20, motor 21, crank 22, transmission module 30, connecting rod 31, first slider 32, execution module 40, execution rod 41, second slider 42, amplitude module 50, movable rod 51, fixed rod 52, connecting rod 53. Detailed Implementation

[0015] Combination Figure 1 , Figure 2 A variable amplitude flapping wing drive mechanism with quick-return motion characteristics includes a frame 10, a drive module 20, a transmission module 30, an execution module 40, and a variable amplitude module 50.

[0016] The frame 10 includes a main rod 11 and a mounting base 12; the main rod 11 and the mounting base 12 can be configured as an integrated structure or fixedly connected. The drive module 20 is mounted on the mounting base 12; the transmission module 30 is sleeved on the main rod 11 and connected to the drive module 20; the execution module 40 is connected to the transmission module 30; the amplitude converter 50 is mounted on the main rod 11 and is linked with the execution module 40 to adjust the flapping amplitude.

[0017] The drive module 20 includes a motor 21 and a crank 22, and the transmission module 30 includes a connecting rod 31 and a first slider 32. The motor 21 is fixedly mounted on the frame mounting base 12, and the crank 22 is fixedly connected to the output shaft of the motor 21. The motor 21 and crank 22 are offset relative to the central axis of the frame main rod 11. The rotation of the motor 21 drives the crank 22 to rotate. One end of the connecting rod 31 is hinged to the crank 22, and the other end is hinged to the first slider 32 mounted on the frame main rod 11, thereby driving the first slider 32 to perform periodic reciprocating linear motion on the frame main rod 11. Due to the offset structure, the reciprocating motion of the first slider 32 has a quick-return characteristic, thus optimizing the dynamic performance of the flapping wing.

[0018] The transmission module 30 includes a first slider 32 sleeved on the main rod 11 and a connecting rod 31 hinged between the crank 22 and the first slider 32.

[0019] The execution module 40 includes an execution rod 41 and a second slider 42. One end of the execution rod 41 is rotatably connected to the first slider 32, and the execution rod 41 passes through the second slider 42, which restricts the degree of freedom of the execution rod 41. When the first slider 32 reciprocates along the main rod 11, the execution rod 41 is constrained by the second slider 42 to form a swing fulcrum, thereby realizing periodic up-and-down swaying.

[0020] The amplitude transformer module 50 includes a movable rod 51, a fixed rod 52, and a connecting rod 53. The movable rod 51 is slidably sleeved on the main frame rod 11, and is driven to move up and down along the main frame rod 11 by a threaded joint or push rod motor. The fixed rod 52 is fixedly mounted on the main frame rod 11. The connecting rod 53 is hinged to both the movable rod 51 and the fixed rod 52. Specifically, the hinge point between the connecting rod 53 and the fixed rod 52 forms a lever fulcrum. One end of the connecting rod 53 is hinged to the movable rod 51, and the other end is hinged to the second slider 42. Because the second slider 42 is connected to the connecting rod 53, its position on the actuator rod 41 is locked. The movable rod 51 is provided with a guide groove to guide the connecting rod 53 to rotate around its hinge point with the fixed rod 52. One end of the connecting rod 53 is slidably engaged in the first guide groove by a pin. When the movable rod 51 slides along the main rod 11, the lever transmission of the connecting rod 53 drives the second slider 42 to move along the length of the actuator 41, thereby changing the fulcrum position of the actuator 41 during its flapping motion. The connecting rod 53 forms a lever amplification mechanism through the fixed rod 52, which converts the displacement of the movable rod 51 into the displacement of the second slider 42. By changing the fulcrum position, the flapping amplitude of the actuator 41 is adjusted while keeping the input displacement of the first slider 32 constant.

[0021] like Figure 1 and Figure 2As shown, the drive module 20 of the present invention outputs power through the motor 21, driving the crank 22 to rotate in a circle around the output axis of the motor at a constant angular velocity ω. Since a fixed offset distance e is set between the output axis of the motor 21 and the central axis of the main rod 11 in the frame 10, this structure constitutes an offset crank-slider mechanism in spatial topology. When the crank 22 rotates, the circular motion is converted into a reciprocating linear displacement of the first slider 32 along the axis of the main rod 11 through the hinge constraint of the transmission connecting rod 31. Due to the existence of the offset distance e, when the first slider 32 runs on the main rod 11 to the upper limit position (upper dead point) and the lower limit position (lower dead point), the included angle between the two extreme positions of the crank 22 (i.e., the two states where the crank and connecting rod are collinear) is no longer 180°, thus generating an extreme position angle θ. During one revolution of the motor 21 in a unidirectional constant speed rotation, the crank angle ϕ1 corresponding to the flapping wing's downward movement along the axis of the main rod 11 is smaller than the crank angle ϕ2 corresponding to the flapping wing's rebound and upward movement. The first slider 32 drives the actuator 41 to reciprocate around the fulcrum formed by the second slider 42 through a hinged connection. Therefore, within a single motion cycle, the time taken for the actuator 41 to fall is significantly shorter than that of the rebound phase, thus giving the flapping wing a rapid return motion characteristic of "fast fall, slow rebound" from a geometrical source.

[0022] To more clearly illustrate the working principle of this embodiment, an analytical geometric model is constructed for rigorous proof. Let the effective radius of rotation of crank 22 be R, and the length of connecting rod 31 be L. According to the physical assembly feasibility constraints of the mechanism, the offset distance e must satisfy: e <L-R。

[0023] When the first slider 32 reaches the upper limit position (top dead center A1), the crank 22 and connecting rod 31 are in a collinear state. At this time, the distance from the center O of the motor output shaft to A1 is:

[0024] ;

[0025] When the first slider 32 reaches its lower limit position (lower dead center A2), the crank 22 and connecting rod 31 are in a stretched collinear state. At this time, the distance from the center O of the motor output shaft to A2 is...

[0026] ;

[0027] In a right triangle, based on boundary geometric relationships, the difference between the angles between the crank and the line parallel to the main rod at its two extreme positions is the extreme position angle θ. According to trigonometric relationships, the extreme position angle can be obtained by the following formula:

[0028] θ=arcsin(e / (LR))-arcsin(e / (L+R));

[0029] Since the motor rotates clockwise at a constant angular velocity ω, the angle through which the crank rotates during the downward phase (corresponding to the outward stroke, when the slider moves from the top dead center A1 to the bottom dead center A2) is: The time taken for the dive is During the rebound phase (corresponding to the return stroke, the slider moves from the bottom dead center A2 to the top dead center A1), the corresponding angle rotated by the crank is: The time taken for the dive is Therefore, t1 < t2, meaning the time of the fall is shorter than the time of the rebound.

Claims

1. A flapping wing drive mechanism with quick-return motion characteristics and variable amplitude, characterized in that, Includes a motor (21), a main rod (11), a first slider (32), an actuator (41), a second slider (42), a fixing rod (52), and a connecting rod (53), among which The motor (21) is located at the bottom of the main rod (11) and offset along the central axis of the main rod (11). The first slider (32) is slidably mounted on the main rod (11). The first slider (32) is connected to the output shaft of the motor (21) via a drive component. The fixing rod (52) is fixed to the main rod (11) and located above the first slider (32). Two actuators (41) are provided, and each actuator (41) is rotatably connected to the first slider (32). Two second sliders (42) are provided, and each second slider (42) is slidably connected to the corresponding actuator (41). Two connecting rods (53) are provided. The lower end of each connecting rod (53) is rotatably connected to the corresponding second slider (42), and the middle part of each connecting rod (53) is rotatably connected to the corresponding end of the fixing rod (52).

2. The flapping wing drive mechanism according to claim 1, characterized in that, It also includes a movable rod (51). The movable rod (51) is slidably mounted on the main rod (11) and located above the fixed rod (52) at the middle. Straight guide grooves are provided at both ends of the movable rod (51) along its own axis. The upper end of the connecting rod (53) is set in the corresponding guide groove and slides in the guide groove.

3. The flapping wing drive mechanism according to claim 1 or 2, characterized in that, An offset distance is provided between the output axis of the motor (21) and the central axis of the main rod (11).

4. The flapping wing drive mechanism according to claim 1 or 2, characterized in that, The drive component includes a crank (22) and a connecting rod (31), wherein One end of the crank (22) is fixedly connected to the output shaft of the motor (21) for rotation. One end of the connecting rod (31) is hinged to the other end of the crank (22). The other end of the connecting rod (31) is hinged to the first slider (32).

5. The flapping wing drive mechanism according to claim 1 or 2, characterized in that, Two actuators (41) are symmetrically distributed along the central axis of the main rod (11), and two second sliders (42) are symmetrically distributed along the central axis of the main rod (11).

6. The flapping wing drive mechanism according to claim 1 or 2, characterized in that, A friction-reducing layer or rolling bearing is provided between the first slider (32) and the main rod (11), and between the second slider (42) and the actuator (41).

7. The flapping wing drive mechanism according to claim 1 or 2, characterized in that, The cross-section of the main rod (11) is polygonal, which is used to restrict the first slider (32) and the movable rod (51) from rotating about the axis of the main rod (11).

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