CN115258154A

CN115258154A - Active and passive flexible bird-like flapping wing aircraft

Info

Publication number: CN115258154A
Application number: CN202211086200.4A
Authority: CN
Inventors: 汪超; 刘博�; 武静; 陈曼媛; 宋加雷; 朱永乐
Original assignee: Dongguan University of Technology
Current assignee: Dongguan University of Technology
Priority date: 2022-09-06
Filing date: 2022-09-06
Publication date: 2022-11-01

Abstract

An active and passive flexible bird-like flapping wing aircraft comprises a driving mechanism, a rack, a tail wing mechanism and two wing wings, wherein the driving mechanism is arranged on the rack to drive the two wing wings to flap up and down, and the tail wing mechanism is arranged at the tail of the rack to adjust the flight attitude of the aircraft; further comprising a passive compliant mechanism, each said wing comprising an inner wing and an outer wing; the inner wing comprises an inner wing rod, an inner wing support rod and two inner wing plates; the outer wing comprises an outer wing rod and a plurality of outer wing plates, the two inner wing plates are connected with the inner wing support rod through the inner wing rod, the inner wing plates on the inner sides are fixed on the rack, the plurality of outer wing plates are fixed on the outer wing rod, and the inner wing rod is connected with the outer wing rod through a passive flexible mechanism; the passive flexible mechanism is a variable stiffness structure, and the variable stiffness structure is formed by connecting a plurality of connecting rods and flexible hinges for connecting adjacent connecting rods in series. The invention has stable and reliable structure, can improve the problem that the flapping wing of the aircraft is relatively fixed, and improves the self-regulation capability to environmental change.

Description

Active and passive flexible bird-like flapping wing aircraft

Technical Field

The invention relates to an aircraft, in particular to an active and passive flexible bird-like flapping wing aircraft.

Background

As a new bionic aircraft, the bird-like flapping wing aircraft mainly generates lift force and thrust force through continuous flapping motion of wings. Compared with a rotor wing aircraft and a fixed wing aircraft, the bird-like flapping wing aircraft has the advantages of stronger maneuverability and flexibility, good bionic property, low noise, high pneumatic efficiency, long working sustainable time and the like.

The flexibility of the wings has a significant impact on the aerodynamic performance of the ornithopter. However, the existing flapping wing aircraft mainly studies flexible wings by using mechanical motion to enable the wings to complete active flexible deformation, and providing lift force through continuous flapping of the wings. The driving mechanism of the active flexible deformation wing is generally a single-degree-of-freedom mechanism, the deformation motion of the wing in the flapping process is used as the fixed flapping motion, the difference between the lift force generated in one flapping cycle and the negative lift force is almost the same, and the energy utilization efficiency is low. And the aircraft has poor adaptability to the change of the external environment, and the change of the external environment easily causes the unstable phenomenon of the flight process.

Through the search of patent documents, CN106043692A discloses a multi-degree-of-freedom bird-like flapping wing aircraft, which adopts a rubber flexible slotting mechanism, and performs slotting treatment on rubber materials, so that wings can deflect to a certain extent in the processes of up-down flapping and deflection through the plastic deformation of the materials, and the influence on the chord-direction deformation is realized.

Disclosure of Invention

The invention provides an active and passive flexible bird-like flapping wing aircraft, which overcomes the defects of the prior art. The aircraft has stable and reliable structure, can improve the energy utilization efficiency, solves the problem that the flapping wings of the aircraft are relatively fixed, and improves the self-adjusting capability to environmental change.

An active and passive flexible bird-like flapping wing aircraft comprises a driving mechanism, a rack, a tail wing mechanism and two wings, wherein the driving mechanism is arranged on the rack to drive the two wings to flap up and down, and the tail wing mechanism is arranged at the tail of the rack to adjust the flight attitude of the aircraft; further comprising a passive compliant mechanism, each of said wings comprising an inner wing and an outer wing;

the inner wing comprises an inner wing rod, an inner wing support rod and two inner wing plates; the outer wing comprises an outer wing rod and a plurality of outer wing plates, the two inner wing plates are connected with an inner wing support rod through the inner wing rod, the inner wing plates on the inner sides are fixed on the rack, the plurality of outer wing plates are fixed on the outer wing rod, the inner wing rod is connected with the outer wing rod through a passive flexible mechanism, and the inner wing support rod is connected with the passive flexible mechanism through a spherical pair; the passive flexible mechanism is a variable stiffness structure, the variable stiffness structure is formed by connecting a plurality of connecting rods and flexible hinges for connecting adjacent connecting rods in series, the flexible hinges are semi-cylindrical rings, a gap surface is arranged between the adjacent connecting rods, and the gap surface is obliquely arranged upwards along the radial end surface of the semi-cylindrical ring and is communicated with the inner annular surface of the semi-cylindrical ring.

Compared with the prior art, the invention has the beneficial effects that:

the passive flexible mechanism is designed, so that the folding deformation of the wing with variable rigidity for the vertical flapping of the aircraft is realized in the flapping process of the active and passive flexible bird-like flapping wing aircraft, the average lift force in a single flapping cycle is improved, the problem of relatively fixed flapping wing actions of the aircraft is solved, and the self-adjusting capability of the aircraft on environmental change is improved.

The design of the driving mechanism enables the flapping-wing control mechanism to truly simulate the flapping amplitude of birds, realize symmetric flapping of two wings, avoid generating large rolling moment, and have simple design and low requirements on parts.

The technical scheme of the invention is further explained by combining the drawings and the embodiment:

drawings

FIG. 1 is a perspective view of an active and passive flexible bird-like ornithopter of the present invention;

FIG. 2 is a schematic layout of a wing;

FIG. 3 is a schematic view of the connection of the inner wing rod, passive flexible hinge and outer wing rod;

FIG. 4 is a schematic structural view of a passive flexible hinge;

FIG. 5 is a schematic view of an outer fin wing twist mechanism;

FIG. 6 is a schematic view of a drive mechanism;

fig. 7 is a schematic view of a tail mechanism.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only used as examples, and the protection scope of the present invention is not limited thereby.

It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the present invention belongs.

As shown in fig. 1-2, the active and passive flexible bird-like flapping wing aircraft of the present embodiment includes a driving mechanism 1, a frame 2, a tail mechanism 3 and two wings 4, wherein the driving mechanism 1 is mounted on the frame 2 to drive the two wings 4 to flap up and down, and the tail mechanism 3 is disposed at the tail of the frame 2 to adjust the flight attitude of the aircraft; also included are passive compliant mechanisms 5, each of said wings comprising an inner wing 41 and an outer wing 42;

the inner wing 41 comprises an inner wing rod 411, an inner wing support rod 412 and two inner wing plates 413; the outer wing 42 comprises an outer wing rod 421 and a plurality of outer wing plates 422, two inner wing plates 413 are connected with an inner wing support rod 412 through inner wing rods 411, the inner wing plates 413 on the inner side are fixed on the frame 2, the plurality of outer wing plates 422 are fixed on the outer wing rod 421, the inner wing rods 411 are connected with the outer wing rod 421 through a passive flexible mechanism 5, and the inner wing support rods 412 are connected with the passive flexible mechanism 5 through a spherical pair;

the two groups of inner wings 41 and the two groups of outer wings 42 of the present embodiment are symmetrically disposed on two sides of the fuselage, optionally, the two groups of inner wings are skeleton structures that are processed by hollowing; the inner wing rod 411 is connected with the outer wing rod 421 through a passive flexible mechanism 5, and the arrangement of the passive flexible mechanism 5 enables the inner wing and the outer wing of the aircraft to complete variable stiffness deformation of up-and-down flapping actions in the flapping process. The fuselage contains frame 2 and spacing fixed subassembly 38, and tail mechanism 3 links to each other with frame 2 through being connected with spacing fixed subassembly 38 cooperation, and spacing fixed subassembly 38 is connected with frame 2 cooperation. Preferably, the inner fin 41, the outer fin 42 and the frame 2 are made of carbon fiber material, which has light weight and high strength, so as to reduce the weight of the aircraft and meet the strength requirement.

As shown in fig. 3 to 4, the passive flexible mechanism 5 is a variable stiffness structure, the variable stiffness structure is formed by connecting a plurality of connecting rods 51 and compliant hinges 52 connecting adjacent connecting rods in series, the compliant hinges 52 are semi-cylindrical rings, a gap surface 510 is arranged between adjacent connecting rods 51, and the gap surface 510 is arranged obliquely upward along the radial end surface of the semi-cylindrical ring and is communicated with the inner annular surface of the semi-cylindrical ring. The arrangement of the passive flexible mechanism 5 ensures that the inner wing and the outer wing of the aircraft can complete the variable rigidity deformation of the up-and-down flapping action in the flapping process.

Typically, the passive compliance mechanism 5 is connected to the inner wing bar 411 or the outer wing bar 421 by wing links 53.

The ideal stiffness of the passive compliant mechanism of this structure is non-linear (variable stiffness). When the flapping wings are upward, the flexible spine can enable the wings to deform in the folding and bending direction of the flapping wings under the downward resistance of air, and the flexible spine is similar to a torsion spring; when the wings are flapping downward, they are subjected to upward air resistance and can become stiff, with greater bending stiffness, because the inclined surfaces will contact each other, similar to a fixed rod. This structure achieves: when upward load is applied (wings flap upwards, air acting force is upward), the rigidity is high, the deformation is small, the area of the wings facing the wind is large, and the generated lift force is large. When downward load is applied (wings swing upwards, air acting force is downward), the rigidity is small, the deformation is large, and torsion occurs, so that the area of the wings facing the windward is small, and the generated resistance is reduced. The overall net lift is increased within a flapping cycle (flapping down and waving up).

Compared with the background art reference CN106043692A, the passive flexible mechanism 5 of the present embodiment realizes variable stiffness deformation in up-and-down flapping, the mechanism can be bent and folded when upward flapping, the mechanism can be analogized to a fixed rod when downward flapping, and the amount of deformation of the wing due to air resistance can be changed by adjusting the number of the flexible hinges and the geometric shape of the joints in the passive flexible mechanism 5, and the passive flexible mechanism 5 has no influence on chordwise deformation, and only realizes passive flexible deformation in the extending direction of the wing.

Optionally, the material of the passive flexible mechanism 5 according to the above embodiment is nylon 101. The flapping wing mechanism is processed by a 3D printing technology, has high precision, can generate large enough unfolding flexible deformation when the aircraft flaps, and is fixed with the inner wing rod and the outer wing rod by the passive flexible mechanism 5 through the wing connecting piece 53. The amount of deformation of the passive flexible mechanism 5 is related to the ambient air flow changes and the number of compliant hinges and the flexible joint geometry of the mechanism itself. The working principle is as follows: when the wing flaps downwards under the action of air resistance and the flexible deformation structure is subjected to upward loading force (the wing flaps downwards and the air acting force is upward), the passive flexible mechanism 5 is shaped like a fixed rod, has high rigidity and small deformation, and completely flattens the inner wing and the outer wing, so that the area facing the windward is large, and the generated lift force is large; when the wings flap upwards, and downward load is applied to the passive flexible mechanism 5 (the wings swing upwards, the air acting force is downward), the rigidity of the flexible deformation structure is small, the deformation is large, the inner wing and the outer wing are folded and deformed in the unfolding direction, the area facing the wind is small, and the resistance is reduced.

As a possible embodiment, as shown in fig. 6, the active and passive flexible bird-like flapping wing aircraft further comprises an outer wing torsion mechanism 6, which comprises a steering engine B61 and a bracket 62; the output shaft of the steering engine B61 is arranged at the end part of the outer wing rod 421, and the shell of the steering engine B61 is arranged on the outer wing 42 through a bracket 62. The tail end of the outer wing rod 421 is used to control the chord torsion of the wing by using a steering engine B61 (research shows that the closer the wing is to the trunk, the smallest torsion angle is, the farther the trunk is forced, the larger the torsion angle is, and the largest torsion angle is at the end point of the wing farthest from the trunk). The design is that the inner wing part does not perform chordwise twisting motion, the outer wing part performs chordwise twisting motion, the steering engine B61 drives the outermost outer wing plates (wing profiles) to perform chordwise twisting, and meanwhile due to the wrapping of the wing skins, when the outermost outer wing plates (wing profiles) perform chordwise twisting, the outer wing plates (wing profiles) can drive the wing profiles on other outer wings to perform twisting. In order to detect the degree of torsion, a torque sensor 63 is arranged at the output end of the steering engine B61 to realize the measurement of torsion.

As a possible embodiment, as shown in fig. 6, the driving mechanism 1 includes a steering engine a11, a gear a12, a gear B13, a gear C14, two gears D15, two rockers 17, and four cranks 16; the steering engine A11 is installed on the rack 2, the gear A12 is installed on an output shaft of the steering engine A11, the gear B13 and the gear C14 are coaxially arranged and are rotatably arranged on the rack 2, the two gears D15 are meshed and rotatably arranged on the rack 2, the gear A12 is meshed with the gear B13, the gear C14 is meshed with one of the gears D15, each gear D15 is correspondingly provided with a connecting rod 17 and two cranks 16, one ends of the two cranks 16 are rotatably connected, the other ends of the two cranks 16 are respectively rotatably connected with the gear D15 and a rocker 17, the other end of the connecting rod 17 is rotatably connected with the inner wing rod 411, and the inner wing rod 411 is rotatably connected with the rack 2.

The driving mechanism 1 realizes the up-and-down flapping of the wings through the step-by-step transmission of gears, and the two cranks are extreme positions of the flapping action of the wings when being collinear. Optionally, in the design of the gear train, the gear is made of ABS (acrylonitrile butadiene styrene) in a unified mode, the modulus is 0.5mm, the reference circle of the gear is reduced as far as possible on the premise that the transmission ratio is guaranteed, the weight is reduced, and the volume ratio of the gear train is reduced. The gears are installed according to the center distance, and the low-speed large gear is fixed on the rack through the interference fit of the bearing and the shaft, so that the friction loss is reduced, and the falling is prevented. The high-speed gear wheel is directly fixed with the shaft in an interference fit manner, the shaft and the rack are fixed in an interference fit manner through a bearing and a bearing block respectively. And the bearing seat is fixed with the frame through a pin shaft, so that the friction loss is reduced, and the transmission reliability is ensured. The cranks are fastened with the gears through screws, and the two cranks are required to be symmetrically installed in order to ensure the symmetry of the two-wing flapping actions of the flapping-wing prototype in the assembling process.

As shown in fig. 7, as a possible embodiment, the tail wing mechanism 3 includes a steering gear C31, a steering gear D32, a connecting rod a33, a connecting rod B34, a tail wing 35, a connecting frame 36 and a connecting seat 37;

the connecting frame 36 is installed on the machine frame 2, the steering engine C31 is installed on the connecting frame 36, the connecting rod A33 is rotatably connected with the connecting rod B34, the connecting seat 37 is rotatably connected with the connecting rod B34, an output shaft of the steering engine C31 is connected with the connecting rod A33 to control the tail wing 35 to perform pitching motion, the connecting seat 37 is rotatably connected with the connecting frame 36, and the tail wing 35 is installed on an output shaft of the steering engine D32 to control the tail wing 35 to horizontally swing.

The main movement of the tail wing is two degrees of freedom of turning in the vertical direction and twisting in the left-right direction, and the current tail wing mainly has a single-piece type, a horizontal tail vertical tail wing and an inverted V-shaped tail wing. In the flight process of the flapping wing aircraft, the operation postures of the aircraft such as pitching deflection and the like can be realized by changing the posture of the tail wing. The function of changing the flight track of the bionic flapping wing flying robot is realized by adopting the torsion and the pitching of the tail wing. Preferably, the tail wing type adopts a horizontal tail vertical tail wing, the two steering engines are used for controlling the transmission of a connecting rod, the steering engines 31 are used for controlling the swinging, and the driving of a connecting rod mechanism is used for realizing the up-and-down swinging of the tail wing on a vertical plane; the steering engine 32 is mounted on the connecting base 37 and directly connected with the tail wing 35 to control the swinging of the deflection thereof, and the two are combined together to complete the common control of the posture of the tail wing.

The present invention is not limited to the above embodiments, and those skilled in the art can make various changes and modifications without departing from the scope of the invention.

Claims

1. An active and passive flexible bird-like flapping wing aircraft comprises a driving mechanism (1), a rack (2), a tail wing mechanism (3) and two wing wings (4), wherein the driving mechanism (1) is installed on the rack (2) to drive the two wing wings (4) to flap up and down, and the tail wing mechanism (3) is arranged at the tail of the rack (2) to adjust the flight attitude of the aircraft;

the method is characterized in that: further comprising passive compliant mechanisms (5), each of said wings comprising an inner wing (41) and an outer wing (42);

the inner wing (41) comprises an inner wing rod (411), an inner wing support rod (412) and two inner wing plates (413); the outer wing (42) comprises an outer wing rod (421) and a plurality of outer wing plates (422), two inner wing plates (413) are connected with an inner wing support rod (412) through inner wing rods (411), the inner wing plates (413) on the inner side are fixed on the rack (2), the plurality of outer wing plates (422) are fixed on the outer wing rod (421), the inner wing rods (411) are connected with the outer wing rods (421) through passive flexible mechanisms (5), and the inner wing support rods (412) are connected with the passive flexible mechanisms (5) through spherical pairs;

the passive flexible mechanism (5) is a variable stiffness structure, the variable stiffness structure is formed by connecting a plurality of connecting rods (51) and compliant hinges (52) for connecting adjacent connecting rods in series, the compliant hinges (52) are semi-cylindrical rings, a gap surface (510) is arranged between the adjacent connecting rods (51), and the gap surface (510) is obliquely arranged upwards along the radial end surface of the semi-cylindrical ring and is communicated with the inner annular surface of the semi-cylindrical ring.

2. The active and passive flexible bird-like ornithopter of claim 1, wherein: the wing turning mechanism comprises an outer wing turning mechanism (6) which comprises a steering engine B (61) and a bracket (62); an output shaft of the steering engine B (61) is arranged at the end part of the outer wing rod (421), and a shell of the steering engine B (61) is arranged on the outer wing (42) through a bracket (62).

3. The active and passive flexible bird-like ornithopter of claim 1, wherein: the driving mechanism (1) comprises a steering engine A (11), a gear A (12), a gear B (13), a gear C (14), two gears D (15), two rockers (17) and four cranks (16); the steering wheel A (11) is installed on the rack (2), the gear A (12) is installed on an output shaft of the steering wheel A (11), the gear B (13) and the gear C (14) are coaxially arranged and are rotatably arranged on the rack (2), the two gears D (15) are meshed and rotatably arranged on the rack (2), the gear A (12) is meshed with the gear B (13), the gear C (14) is meshed with one of the gears D (15), each gear D (15) is correspondingly provided with one connecting rod (17) and two cranks (16), one ends of the two cranks (16) are rotatably connected, the other ends of the two cranks (16) are respectively rotatably connected with the gears D (15) and the rocking rods (17), the other ends of the connecting rods (17) are rotatably connected with the inner wing rods (411), and the inner wing rods (411) are rotatably connected with the rack (2).

4. The active and passive flexible bird-like ornithopter of claim 1, wherein: the passive flexible hinge (5) is made of nylon 101.

5. The active and passive flexible bird-like ornithopter of claim 1, wherein: the tail wing mechanism (3) comprises a steering engine C (31), a steering engine D (32), a connecting rod A (33), a connecting rod B (34), a tail wing (35), a connecting frame (36) and a connecting seat (37);

a connecting frame (36) is installed on a rack (2), a steering engine C (31) is installed on the connecting frame (36), a connecting rod A (33) is rotatably connected with a connecting rod B (34), a connecting seat (37) is rotatably connected with the connecting rod B (34), an output shaft of the steering engine C (31) is connected with the connecting rod A (33) to control a tail wing (35) to perform pitching motion, the connecting seat (37) is rotatably connected with the connecting frame (36), and the tail wing (35) is installed on an output shaft of the steering engine D (32) to control the tail wing (35) to horizontally swing.

6. The active and passive flexible bird-like ornithopter of claim 1, wherein: the inner wing 41, the outer wing (42) and the frame (2) are all made of carbon fiber materials.