Flapping wing driving mechanism of bionic flapping wing aircraft and design method of flapping wing driving mechanism

Abstract

The invention discloses a flapping wing driving mechanism of a bionic flapping wing aircraft and a design method of the flapping wing driving mechanism, and relates to the field of aircraft structures for simulating birds or insects and other organisms to realize air flight through periodic flapping of one or more pairs of wings. The fan has the advantages of few components, high modularization degree, light structural weight, high strength, adjustable fan wing plane angle and serial expansion, and the cam is easy to disassemble and maintain. The bionic flapping wing aircraft comprises a fuselage and a pair of flapping wings, and the flapping wing driving mechanism comprises a flapping structure used for driving the flapping wings to move up and down and a flapping wing control mechanism used for driving the flapping wings to pitch front and back. The bionic ornithopter is high in bionic property and can be widely applied to the field of ornithopters.

Description

Technical Field

[0001] The present invention relates to the field of aircraft structures which imitate birds, insects and other creatures to achieve aerial flight through the periodic flapping of one or more pairs of wings. Background Art

[0002] A bionic flapping-wing aircraft is an aircraft that imitates the periodic flapping of one or more pairs of wings of creatures such as birds or insects to achieve aerial flight. The flapping wings of this type of aircraft can not only generate upward lift, but also generate forward propulsion, and have more degrees of freedom of movement, so that the aircraft can achieve multiple flight modes such as forward flight, backward flight, turning, climbing, diving, and hovering, and can switch between any two modes, with strong maneuverability and flexibility. It has bionics, concealment, and portability. It is generally hand-thrown takeoff and gliding landing. Takeoff and landing are not restricted by the site. It can be widely used in civil fields such as entertainment, biochemical detection, environmental monitoring, bird and insect repellent, urban inspection, and natural or man-made disaster monitoring, as well as defense fields such as battlefield reconnaissance, patrol, raid, signal interference, and urban street fighting. At present, bionic flapping-wing aircraft are gradually developing in the direction of systematization, miniaturization and lightweight, intelligence, and clustering, especially the reduction of its volume, which has always been the development direction of this field.

[0003] Specifically speaking of the driving of bionic flapping-wing aircraft, the main driving methods include DC motors, electromagnetic or piezoelectric drives. In 2016, an article entitled "Apiezo-driven flapping wing mechanism for micro air vehicles" published by the National University of Singapore proposed to use piezoelectric elements as the driving source to design a flapping mechanism. Among the above driving methods, the electromagnetic type is difficult to integrate due to the large size of the electromagnetic coil compared to other electronic components, and the piezoelectric type requires an extremely high driving voltage to produce deformation. Its power module is often unable to be mounted on the aircraft, and the cost is relatively high. The above shortcomings limit the widespread application of the latter two driving methods in bionic flapping-wing micro air vehicles.

[0004] Therefore, at present, bionic flapping-wing aircraft still mainly use micro-sized DC motors as driving sources, and realize the periodic reciprocating motion of flapping wings through various combinations of gear transmission mechanisms and multi-link mechanisms. However, the disadvantages of such structures are: 1. The manufacturing and installation precision of gears are very high. When the precision is low, it is easy to generate large noise and vibration, and easy to wear; 2. For example, crank rocker mechanisms may make the flapping wings on both sides of the aircraft move inconsistently, and their structures are relatively complex and occupy a large space. The disadvantages of the above mechanisms are not good for the stability and reliability of flapping wings, which undoubtedly have a great adverse effect on the miniaturization of flapping systems.

[0005] At present, there are related invention patents that use cam mechanisms, including cylindrical cams and equal-width cams. For example, two Chinese invention patents with application number CN201110154950.6 and title "A cylindrical cam flapping wing drive mechanism" and application number CN201810068635.3 and title "A cylindrical cam universal joint bird-like flapping wing flight device" both use cylindrical cams to drive flapping wings, that is, a curved groove with a certain motion function is opened on the cylindrical surface, and its rotation will drive the embedded slider to move in a straight line in a fixed plane, and the slider will then drive the flapping wings on both sides to perform flapping motion without phase difference through a pair of connecting rod mechanisms. However, due to the limitations of the geometric shape, this type of cam cannot realize complex motion laws, and the slider is always in friction with the groove, so it is more prone to wear and requires long-term lubrication. The Chinese invention patent with application number CN200810235542.1 and name “Micro-sized flapping-wing aircraft” consists of a fuselage, wings, cams and engines, wherein the equal-width cam mechanism is at a distance from the inner wall of the fuselage, and the rotation of the cam causes the follower of the equal-width cam mechanism to translate up and down, and then the wing flaps up and down through the connecting rod. Since the wing in the invention design is only connected to the connecting rod through springs and bearings, the wing will shake during the up and down translation of the equal-width cam mechanism, and the root of the wing will be displaced, which greatly affects the flight efficiency of the aircraft. The Chinese invention patent with application number CN201911363858.3 and name “Flapping-wing drive mechanism capable of increasing high lift and forward power” also uses the equal-width cam mechanism as the active part to realize the periodic reciprocating motion of the flapping wing, and the flapping wing is tilted forward at a certain angle with the horizontal plane, and can change the wing area, but the problem brought by such a design is that the structure becomes more complicated, and parts such as gears, racks, and worms are introduced, which increases the design difficulty and weight. Summary of the invention

[0006] In view of the above problems, the present invention proposes a flapping-wing drive mechanism for a bionic flapping-wing aircraft, which has few components, a high degree of modularization, a light structure, high strength, adjustable wing plane angle, serial expansion, and a cam that is easy to disassemble and maintain.

[0007] The technical solution of the present invention is as follows: the bionic flapping-wing aircraft comprises a fuselage 4 and a pair of flapping wings 3, the flapping-wing driving mechanism comprises a flapping structure 1 for driving the flapping wings 3 to move up and down and a flapping-wing control mechanism 2 for driving the flapping wings 3 to pitch forward and backward;

[0008] The flapping wing control mechanism 2 includes a rotary power source, a steering gear rocker arm 22, a translation link 231 and a front rocker arm 171, wherein the rotary power source is fixedly mounted on the fuselage 4, the bottom end of the steering gear rocker arm 22 is fixedly connected to the output shaft of the rotary power source, the front rocker arm 171 is arranged on the front side of the steering gear rocker arm 22, and the bottom end of the front rocker arm 171 is hinged on the fuselage 4, the front and rear ends of the translation link 231 are respectively hinged to the top end of the front rocker arm 171 and the top end of the steering gear rocker arm 22, and the front rocker arm 171 and the steering gear rocker arm 22 are of equal length and parallel;

[0009] like Figure 1 , 4 As shown in 6, the flapping structure 1 is installed on the fuselage 4 and connected to the front rocker arm 171;

[0010] The flapping structure 1 includes a frame 17, a linear reciprocating power source, an upper connecting rod 131, an upper connecting rod 2 132, a side connecting rod 151, and a side connecting rod 2 152;

[0011] The frame 17 is fixedly connected to the front rocker arm 171, the lower parts of the side link 151 and the side link 152 are respectively hinged on the left and right sides of the frame 17, and the lower parts of the side link 151 and the side link 152 have mounting ends extending out of the frame 17; the top ends of the upper link 131 and the upper link 132 are hinged to each other, and the bottom ends of the two are respectively hinged to the side link 151 and the side link 152, and the linear reciprocating power source is installed on the frame 17, and the top ends of the upper link 131 and the upper link 132 are driven to reciprocate up and down by the linear reciprocating power source;

[0012] A pair of flapping wings 3 are symmetrically arranged on both sides of the frame 17, and their roots are fixedly connected to the mounting ends of the side connecting rod 1 151 and the side connecting rod 2 152.

[0013] Further, in order to maintain the stability of the front and rear pitching movements, the flapping wing control mechanism 2 also includes a fuselage rocker arm 24, a second translation link 232 and a second front rocker arm 172, the bottom end of the fuselage rocker arm 24 is hinged on the fuselage 4, the second front rocker arm 172 is arranged on the front side of the fuselage rocker arm 24, and the bottom end of the second front rocker arm 172 is hinged on the fuselage 4, the front and rear ends of the second translation link 232 are respectively hinged on the top of the second front rocker arm 172 and the top of the fuselage rocker arm 24, and the second front rocker arm 172 and the fuselage rocker arm 24 are of equal length and parallel;

[0014] The first translation link 231 and the second translation link 232 are of equal length and parallel.

[0015] Furthermore, the rotational power source is a steering gear 21 .

[0016] Furthermore, the flapping structure 1 also includes a spring 161 and a spring 162, the bottom ends of the spring 161 and the spring 162 are fixedly connected to the frame 17, and the top ends of the springs are respectively fixedly connected to the upper connecting rod 131 and the upper connecting rod 2 132, the spring 161 and the spring 162 are symmetrically arranged along the center of the frame 17, and both are arranged vertically.

[0017] Furthermore, the linear reciprocating power source includes an equal-width cam 11, a rectangular frame push rod 12 and a drive motor 14, the rectangular frame push rod 12 includes a rod portion and a frame portion connected as one, the top end of the rod portion is hinged with the top ends of the upper connecting rod 131 and the upper connecting rod 2 132, the frame portion is under the rod portion, the equal-width cam 11 is accommodated in the frame portion, and its upper and lower sides are in contact with the inner wall of the frame portion at the same time, the housing of the drive motor 14 is fixedly mounted on the frame 17, and its output shaft is vertically fixedly connected to the equal-width cam 11, and a spacing is left between the output shaft of the drive motor 14 and the center of the equal-width cam 11; a vertically arranged guide rod is also fixedly connected to the bottom surface of the frame, and the guide rod passes through the frame 17.

[0018] The up and down flapping motion law of the flapping wing 3 can be expressed by the equation when n=1:

[0019] α(t)=A0+A1 sin(ωt+δ1) (1)

[0020] Where α(t) is the flapping angle value at any time of wing movement, t is time, A0 is the initial flapping angle, A1 is the amplitude of the flapping motion, ω=2πf, where f is the flapping frequency, and δ1 is the phase difference of the flapping motion. The above parameters can be obtained from existing research literature.

[0021] According to the design criteria of the equal-width cam mechanism, the motion equation of the follower push rod is:

[0022]

[0023] In the formula, in is the rotation angle of the cam at any time, ω is the rotation angular velocity of the cam, t is the time; n is the number of sides of the profile curve, which is an odd number; e is the eccentricity of the profile curve, and the maximum moving distance of the rectangular frame push rod is 2e. When n=3, Its acceleration is a sinusoidal continuous curve, and the rectangular frame type push rod has neither rigid impact nor flexible impact, thus ensuring that its up and down reciprocating movement is more stable.

[0024] According to the isometric profile theory of equal-width cams, the geometric analytical method is used to obtain the contour vector equation of the cam in polar coordinates. Among them, the contour vector equation of the push-stroke section cam is:

[0025]

[0026] In the formula θ1∈[0,π];

[0027] The vector equation of the cam profile in the return section is:

[0028]

[0029] In the formula, θ2∈[π,2π];

[0030] The follower remains stationary in the far rest section and the near rest section. It can be seen that the far rest section φ S With near rest segment φ S The cam profile of ′ is a circular arc segment:

[0031]

[0032] By solving equations (3) to (6) in sequence, the contour curve of the equal-width cam can be obtained.

[0033] The present invention proposes to replace the gear transmission mechanism with a cam mechanism, and its beneficial effects are as follows:

[0034] 1. Compared with the extremely complex design of a multi-link mechanism to meet certain trajectories, using a cam to meet the trajectory can reduce the size of the mechanism and make the flapping structure simpler and more compact;

[0035] Second, the cam mechanism is easy to design. By simply designing an appropriate cam profile, the follower can obtain the desired motion law, which is crucial for the flight control of the aircraft, helps to reduce weight and improve flight efficiency, and ensures the stable flight of the aircraft in complex environments.

[0036] The flapping structure of the present invention restores the flapping movement of flapping-wing flying animals in nature, especially the movement of the indirect (direct) flight muscles of the thorax position that controls the flapping of wings of insects when they flap their wings. That is, when the rectangular frame push rod moves downward, the flapping wing flaps upward, and the spring is in a compressed state; when the rectangular frame push rod moves upward, the flapping wing flaps downward, and the spring is in a stretched state. In addition, when the flapping structure of the present invention is installed on the fuselage as an integral flapping module of a flapping-wing aircraft, it can be driven by an external servo to tilt at a small angle around the axis of the leading edge rod direction of the wing (i.e., the y-axis defined in the figure), change the flapping plane angle, that is, change the flapping plane of the flapping-wing aircraft; the flapping module can also achieve serial expansion, that is, become a double pair of wings or multiple pairs of wings. Therefore, the present invention has strong bionics and can be widely used in the field of flapping-wing aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a perspective view of the front side of the present invention;

[0038] Figure 2 is a perspective view of the rear side of the present invention;

[0039] Figure 3 It is a schematic diagram of the structure of the present invention;

[0040] Figure 4 It is a schematic diagram of the explosion of the flapping structure in the present invention;

[0041] Figure 5 It is a schematic diagram of the profile curve of the medium-width cam of the present invention;

[0042] Figure 6 is a schematic diagram of a flapping wing control mechanism in the present invention;

[0043] Figure 7 It is a structural schematic diagram of the rack in the present invention;

[0044] Figure 8 It is a schematic diagram of a flapping wing of the present invention.

[0045] The figure shows:

[0046] 1 flapping structure, 2 flapping wing control mechanism, 3 flapping wing, 4 fuselage (the part shown in the figure is the front end of the fuselage, and the rod-shaped part of the fuselage is not shown);

[0047] 11 equal-width cam, 12 rectangular frame push rod, 131 upper connecting rod 1, 132 upper connecting rod 2, 14 driving motor, 151 side connecting rod 1, 152 side connecting rod 2, 161 spring 1, 162 spring 2, 17 frame, 171 front rocker arm 1, 172 front rocker arm 2;

[0048] 21 steering gear, 22 steering gear rocker arm, 231 translation connecting rod 1, 232 translation connecting rod 2, 24 fuselage rocker arm;

[0049] 31 wing leading edge rod, 32 wing longitudinal rib, 33 wing membrane. DETAILED DESCRIPTION

[0050] In order to clearly illustrate the technical features of this patent, this patent is elaborated in detail below through a specific implementation method and in combination with its accompanying drawings.

[0051] This case Figure 1-3 As shown, the bionic flapping-wing aircraft includes a fuselage 4 and a pair of flapping wings 3, and the flapping-wing driving mechanism includes a flapping structure 1 for driving the flapping wings 3 to move up and down and a flapping-wing control mechanism 2 for driving the flapping wings 3 to pitch forward and backward.

[0052] like Figure 6As shown, the flapping wing control mechanism 2 includes a rotary power source, a steering gear rocker arm 22, a translation link 231 and a front rocker arm 171, wherein the rotary power source is fixedly mounted on the fuselage 4, the bottom end of the steering gear rocker arm 22 is fixedly connected to the output shaft of the rotary power source, the front rocker arm 171 is arranged at the front side of the steering gear rocker arm 22, and the bottom end of the front rocker arm 171 is hinged on the fuselage 4, the front and rear ends of the translation link 231 are respectively hinged to the top end of the front rocker arm 171 and the top end of the steering gear rocker arm 22, and the front rocker arm 171 and the steering gear rocker arm 22 are of equal length and parallel;

[0053] In order to maintain the stability of the forward and backward pitching movements, the flapping wing control mechanism 2 further includes a fuselage rocker arm 24, a second translation link 232 and a second front rocker arm 172, the bottom end of the fuselage rocker arm 24 is hinged on the fuselage 4, the second front rocker arm 172 is arranged on the front side of the fuselage rocker arm 24, and the bottom end of the second front rocker arm 172 is hinged on the fuselage 4, the front and rear ends of the second translation link 232 are respectively hinged on the top of the second front rocker arm 172 and the top of the fuselage rocker arm 24, and the second front rocker arm 172 and the fuselage rocker arm 24 are of equal length and parallel;

[0054] The first translation link 231 and the second translation link 232 are of equal length and parallel.

[0055] The rotation power source is a steering gear 21 .

[0056] like Figure 1 , 4 As shown in 6, the flapping structure 1 is installed on the fuselage 4 and connected to the front rocker arm 171;

[0057] The flapping structure 1 includes a frame 17, a linear reciprocating power source, an upper connecting rod 131, an upper connecting rod 2 132, a side connecting rod 151, and a side connecting rod 2 152;

[0058] The frame 17 is fixedly connected to the front rocker arm 171 and the front rocker arm 172. The lower parts of the side link 151 and the side link 152 are respectively hinged on the left and right sides of the frame 17, and the lower parts of the side link 151 and the side link 152 have mounting ends extending out of the frame 17. The top ends of the upper link 131 and the upper link 132 are hinged to each other, and the bottom ends of the two are respectively hinged to the side link 151 and the side link 152. The linear reciprocating power source is installed on the frame 17, and the top ends of the upper link 131 and the upper link 132 are driven to reciprocate up and down by the linear reciprocating power source.

[0059] A pair of flapping wings 3 are symmetrically arranged on both sides of the frame 17, and the roots thereof are fixedly connected to the mounting ends of the side connecting rod 1 151 and the side connecting rod 2 152. In this way, as the linear reciprocating power source drives the top ends of the upper connecting rod 1 131 and the upper connecting rod 2 132 up and down, the side connecting rod 1 151 and the side connecting rod 2 152 will also be driven to make a rotational motion, thereby driving the pair of flapping wings 3 to flap up and down. In addition, the flapping structure 1 can drive the translational connecting rod under the drive of the rotational power source, and then drive the flapping structure to flip forward and backward. Finally, by combining the up and down reciprocation and the front and back flipping, the complex motion of simulating the flapping wings of insects can be realized.

[0060] The flapping structure 1 further comprises a spring 161 and a spring 2 162, the bottom ends of the spring 161 and the spring 2 162 are fixedly connected to the frame 17, and the top ends of the spring 161 and the spring 2 162 are respectively fixedly connected to the upper connecting rod 131 and the upper connecting rod 2 132, the spring 161 and the spring 2 162 are symmetrically arranged along the center of the frame 17, and both are arranged vertically. When the flapping wing 3 is stationary, the spring 161 and the spring 2 162 are both in the original state, when the flapping wing 3 flaps up, the spring 161 and the spring 2 162 are both in the compressed state, and when the flapping wing 3 flaps down, the spring 161 and the spring 2 162 are both in the stretched state. In this way, the spring plays a good auxiliary and force-increasing role on the linear power source in a flapping cycle, providing additional driving force for the flapping wing 3.

[0061] The linear reciprocating power source includes an equal-width cam 11, a rectangular frame push rod 12 and a drive motor 14. The rectangular frame push rod 12 includes a rod portion and a frame portion connected as one. The top end of the rod portion is hinged with the top ends of the upper connecting rod 131 and the upper connecting rod 2 132. The frame portion is below the rod portion. The equal-width cam 11 is accommodated in the frame portion, and its upper and lower sides are in contact with the inner wall of the frame portion at the same time. The housing of the drive motor 14 is fixedly mounted on the frame 17, and its output shaft is vertically fixedly connected to the equal-width cam 11. A spacing is left between the output shaft of the drive motor 14 and the center of the equal-width cam 11; a vertically arranged guide rod is also fixedly connected to the bottom surface of the frame, and the guide rod passes through the frame 17.

[0062] The upper and lower sides of the equal-width cam 11 are in contact with the rectangular frame push rod 12 at the same time, and the distance between any two parallel tangents on the contour line of the equal-width cam 11 is equal to the distance D between the upper and lower surfaces of the inner side of the frame of the rectangular frame push rod 12, so that the equal-width cam and the rectangular frame push rod are always in contact; this cam is different from other cams, and its equal width is a restriction frame, that is, the cam is only allowed to move within 180°, and the remaining 180° must be "mirror" symmetrical to the previous 180° movement to maintain a certain width D;

[0063] The contour curve of the equal-width cam 11 is designed according to the flapping law of the wings of flapping-wing flying animals such as birds or insects during flight, and can realize various flapping-wing motion laws. The specific method is to first establish the motion constraint equation of the link motion angle following the flapping angle in the rocker mechanism (the rocker mechanism includes the upper link 131, the upper link 2 132, the side link 151, and the side link 2 152) according to the flapping law of the wings, such as the up and down flapping motion equation of the wings, and obtain the upper and lower limit positions of the rectangular frame push rod according to the flapping angle of the flapping-wing flying animals provided by the existing literature, and further according to the follower push rod motion equation in the design criteria of the equal-width cam mechanism, draw the displacement law curve of the push rod following the cam rotation angle within a cycle, and finally design the contour curve of the cam according to the curve. Based on the equal-width cam equidistant profile, the follower motion law has the following three characteristics: the cam push motion angle φ is equal to the return motion angle φ′; the push motion angle φ and the far rest angle φ S The sum accounts for half of the cam mechanism's working cycle, i.e. φ+φ S =π; the motion law of the return section is limited by the equal width principle and is similar to the motion law of the push section. Therefore, when designing an equal width cam, it is only necessary to determine the base circle radius r b , stroke h, pushing motion angle φ and the motion law of the follower in the pushing section can be used.

[0064] Existing animal flight experiments have found that the periodic flapping kinematic equation of flapping animals can be expressed by Fourier series. Therefore, the up and down flapping motion equation of the wing can be expressed as:

[0065]

[0066] Where α(t) is the flapping angle of the wings at any time, t is time, A0, A n , δ n (n=1,2,3,…) is the Fourier coefficient, ω is the natural frequency; the above coefficients can be obtained by curve fitting from the observed wing motion data, and then the corresponding motion equation is obtained.

[0067] For example, the up and down flapping motion law of the wings of a flapping animal during flight can be expressed by the equation when n=1:

[0068] α(t)=A0+A1 sin(ωt+δ1) (1)

[0069] Where A0 is the initial flapping angle, A1 is the amplitude of the flapping motion, ω = 2πf, where f is the flapping frequency, and δ1 is the phase difference of the flapping motion. The above parameters can be obtained from existing research literature.

[0070] According to the design criteria of the equal-width cam mechanism, the motion equation of the follower push rod is:

[0071]

[0072] In the formula, in is the rotation angle of the cam at any time, ω is the rotation angular velocity of the cam, t is the time; n is the number of sides of the profile curve, which is an odd number; e is the eccentricity of the profile curve, and the maximum moving distance of the rectangular frame push rod is 2e. When n=3, Its acceleration is a sinusoidal continuous curve, and the rectangular frame type push rod has neither rigid impact nor flexible impact, thus ensuring that its up and down reciprocating movement is more stable.

[0073] According to the isometric profile theory of equal-width cams, the geometric analytical method is used to obtain the contour vector equation of the cam in polar coordinates. Among them, the contour vector equation of the push-stroke section cam is:

[0074]

[0075] In the formula θ1∈[0,π];

[0076] The vector equation of the cam profile in the return section is:

[0077]

[0078] In the formula, θ2∈[π,2π];

[0079] The follower remains stationary in the far rest section and the near rest section. It can be seen that the far rest section φ S With near rest segment φ S The cam profile of ′ is a circular arc segment

[0080]

[0081] By solving equations (3) to (6) in sequence, the contour curve of the equal-width cam can be obtained.

[0082] There are many specific implementation ways of the present invention. The above is only the preferred implementation mode of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A flapping-wing drive mechanism for a bionic flapping-wing aircraft, characterized in that: The bionic flapping-wing aircraft comprises a fuselage (4) and a pair of flapping wings (3); the flapping-wing driving mechanism comprises a flapping structure (1) for driving the flapping wings (3) to move up and down, and a flapping-wing control mechanism (2) for driving the flapping wings (3) to pitch forward and backward; The flapping wing control mechanism (2) comprises a rotary power source, a steering gear rocker arm (22), a translation connecting rod (231) and a front rocker arm (171), wherein the rotary power source is fixedly mounted on a fuselage (4), the bottom end of the steering gear rocker arm (22) is fixedly connected to the output shaft of the rotary power source, the front rocker arm (171) is arranged on the front side of the steering gear rocker arm (22), and the bottom end of the front rocker arm (171) is hinged on the fuselage (4), the front and rear ends of the translation connecting rod (231) are respectively hinged to the top end of the front rocker arm (171) and the top end of the steering gear rocker arm (22), and the front rocker arm (171) and the steering gear rocker arm (22) are of equal length and parallel; The flapping structure (1) is mounted on the fuselage (4) and connected to the front rocker arm (171); The flapping structure (1) comprises a frame (17), a linear reciprocating power source, and an upper connecting rod 1 (131), an upper connecting rod 2 (132), a side connecting rod 1 (151), and a side connecting rod 2 (152); The frame (17) is fixedly connected to the front rocker arm 1 (171); the lower parts of the side link 1 (151) and the side link 2 (152) are respectively hinged on the left and right sides of the frame (17); and the lower parts of the side link 1 (151) and the side link 2 (152) have mounting ends extending out of the frame (17); the top ends of the upper link 1 (131) and the upper link 2 (132) are hinged to each other, and the bottom ends of the two are respectively hinged to the side link 1 (151) and the side link 2 (152); the linear reciprocating power source is installed on the frame (17), and the top ends of the upper link 1 (131) and the upper link 2 (132) are driven to reciprocate up and down by the linear reciprocating power source; A pair of flapping wings (3) are symmetrically arranged on both sides of the frame (17), and the roots of the flapping wings are fixedly connected to the mounting ends of the first side connecting rod (151) and the second side connecting rod (152).

2. The flapping-wing driving mechanism of a bionic flapping-wing aircraft according to claim 1, characterized in that: The flapping wing control mechanism (2) also includes a fuselage rocker arm (24), a second translation link (232) and a second front rocker arm (172), wherein the bottom end of the fuselage rocker arm (24) is hinged on the fuselage (4), the second front rocker arm (172) is arranged on the front side of the fuselage rocker arm (24), and the bottom end of the second front rocker arm (172) is hinged on the fuselage (4), the front and rear ends of the second translation link (232) are respectively hinged on the top end of the second front rocker arm (172) and the top end of the fuselage rocker arm (24), and the second front rocker arm (172) and the fuselage rocker arm (24) are of equal length and parallel; The first translation link rod (231) and the second translation link rod (232) are of equal length and parallel.

3. The flapping-wing driving mechanism of a bionic flapping-wing aircraft according to claim 2, characterized in that: The rotation power source is a steering gear (21).

4. The flapping-wing driving mechanism of a bionic flapping-wing aircraft according to claim 1, characterized in that: The flapping structure (1) further comprises a spring 1 (161) and a spring 2 (162). The bottom ends of the spring 1 (161) and the spring 2 (162) are fixedly connected to the frame (17), and the top ends of the spring 1 (161) and the spring 2 (162) are respectively fixedly connected to the upper connecting rod 1 (131) and the upper connecting rod 2 (132). The spring 1 (161) and the spring 2 (162) are symmetrically arranged along the center of the frame (17), and both are arranged vertically.

5. The flapping-wing driving mechanism of a bionic flapping-wing aircraft according to claim 1, characterized in that: The linear reciprocating power source comprises an equal-width cam (11), a rectangular frame push rod (12) and a driving motor (14); the rectangular frame push rod (12) comprises a rod portion and a frame portion connected as one body; the top end of the rod portion is hinged with the top ends of an upper connecting rod 1 (131) and an upper connecting rod 2 (132); the frame portion is located below the rod portion; the equal-width cam (11) is accommodated in the frame portion, and its upper and lower sides are in contact with the inner wall of the frame portion at the same time; the housing of the driving motor (14) is fixedly mounted on the frame (17), and its output shaft is vertically fixedly connected to the equal-width cam (11); a spacing is left between the output shaft of the driving motor (14) and the center of the equal-width cam (11); a vertically arranged guide rod is also fixedly connected to the bottom surface of the frame portion, and the guide rod passes through the frame (17).

6. A method for designing a medium-width cam in a flapping-wing drive mechanism of a bionic flapping-wing aircraft according to claim 5, characterized in that: The up and down flapping motion law of the flapping wing (3) can be expressed by the equation when n=1: α(t)=A0+A1 sin(ωt+δ1) (1) Where α(t) is the flapping angle value at any time of wing movement, t is time, A0 is the initial flapping angle, A1 is the amplitude of the flapping motion, ω=2πf, where f is the flapping frequency, and δ1 is the phase difference of the flapping motion; According to the design criteria of the equal-width cam mechanism, the motion equation of the follower push rod is: In the formula, in is the rotation angle of the cam at any time, ω is the angular velocity of the cam, t is the time; n is the number of sides of the profile curve, which is an odd number; e is the eccentricity of the profile curve, and the maximum moving distance of the rectangular frame push rod is 2e; when n=3, Its acceleration is a continuous sinusoidal curve; According to the isometric profile theory of equal-width cams, the geometric analytical method is used to obtain the contour vector equation of the cam in polar coordinates, where the contour vector equation of the push-stroke segment cam is: In the formula θ1∈[0,π]; The vector equation of the cam profile in the return section is: In the formula, θ2∈[π,2π]; The follower remains stationary in the far rest section and the near rest section. It can be seen that the far rest section φ S With near rest segment φ S The cam profile of ′ is a circular arc segment: By solving equations (3) to (6) in sequence, the contour curve of the equal-width cam can be obtained.

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