A flapping-wing driving mechanism of a bionic flapping-wing aircraft and a design method thereof

Abstract

The present invention discloses a flapping-wing drive mechanism for a bionic flapping-wing aircraft and a design method thereof, relating to the field of aircraft structures that mimic the periodic flapping of one or more pairs of wings of birds, insects, and other organisms to achieve aerial flight. The structure has few components, a high degree of modularity, a light structure, high strength, adjustable wing plane angles, serial expansion, and a cam that is easy to disassemble and maintain. The bionic flapping-wing aircraft includes a fuselage and a pair of flapping wings. The flapping-wing drive mechanism includes a flapping structure for driving the flapping wings to move up and down, and a flapping-wing control mechanism for driving the flapping wings to pitch forward and backward. The present invention has strong biomimetic properties and can be widely used in the field of flapping-wing aircraft.

Description

Technical Field

[0001] The present invention relates to the field of aircraft structures for imitating 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 mimics the periodic flapping of one or more pairs of wings by birds or insects to achieve aerial flight. The flapping wings of this type of aircraft can generate not only upward lift but also forward propulsion, with a large number of degrees of freedom of movement, enabling the aircraft to 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 is biomimetic, stealthy, and portable, and generally takes off by hand and glides to land. Takeoff and landing are not restricted by the site, and can be widely used in civilian fields such as entertainment, biochemical detection, environmental monitoring, bird and insect repellent, urban inspections, and natural or man-made disaster monitoring, as well as defense fields such as battlefield reconnaissance, patrols, raids, signal jamming, and urban street fighting. At present, bionic flapping-wing aircraft are gradually developing towards systematization, miniaturization and lightweighting, intelligence, and clustering. In particular, the reduction of their size has always been the development direction of this field.

[0003] Specifically, the main drive methods for bionic flapping-wing aircraft include DC motors, electromagnetic drives, or piezoelectric drives. In 2016, a paper published by the National University of Singapore titled "Apiezo-driven flapping wing mechanism for micro air vehicles" proposed designing a flapping mechanism using piezoelectric elements as the drive source. Of these drive methods, electromagnetic drives are difficult to integrate due to the bulk of the electromagnetic coils compared to other electronic components, while piezoelectric drives require extremely high drive voltages to produce deformation. Their power modules are often unable to be mounted on aircraft, and their cost is high. These shortcomings limit the widespread application of the latter two drive methods in bionic flapping-wing micro air vehicles.

[0004] Therefore, current bionic flapping-wing aircraft still primarily rely on miniature DC motors as their driving source, achieving periodic reciprocating motion of their flapping wings through various combinations of gear transmission mechanisms and multi-link mechanisms. However, these structures have the following drawbacks: 1. They require extremely high precision in the manufacturing and assembly of the gears; low precision can easily generate significant noise, vibration, and wear; 2. Crank-rocker mechanisms, such as these, can cause inconsistent movement of the flapping wings on either side of the aircraft, and their relatively complex structures occupy a large space. These shortcomings negatively impact the stability and reliability of flapping wings, undoubtedly significantly hindering 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, application number CN201110154950.6, titled "A Cylindrical Cam Flapping Wing Driving Mechanism," and application number CN201810068635.3, titled "A Cylindrical Cam Universal Joint Bird-like Flapping Wing Flying 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. Its rotation will drive the embedded slider to move in a straight line within 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 achieve 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. Chinese invention patent application number CN200810235542.1, entitled "Micro-sized Flapping-Wing Aircraft," consists of a fuselage, wings, a cam, and an engine. The cam mechanism is spaced apart from the inner wall of the fuselage. The rotation of the cam causes the follower of the cam mechanism to translate up and down, which in turn, via a connecting rod, causes the wings to flap up and down. Because the wings in this invention are connected to the connecting rods only via springs and bearings, the wings vibrate and shift at the wing root during the up and down translation of the cam mechanism, significantly affecting the flight efficiency of the aircraft. Chinese invention patent application number CN201911363858.3, entitled "Flapping-Wing Driving Mechanism for Enhancing High Lift and Forward Power," also uses a cam mechanism as the active element to achieve the periodic reciprocating motion of the flapping wings. The flapping wings tilt forward at a certain angle to the horizontal plane, and can also change their wing area. However, this design increases the structural complexity, introducing components such as gears, racks, and worms, making the design more difficult and increasing the weight. Summary of the Invention

[0006] In response to the above problems, the present invention proposes a flapping-wing drive mechanism for a bionic flapping-wing aircraft, which has few components, high modularity, 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 servo rocker arm 22, a translation link 231, and a front rocker arm 171. The rotary power source is fixedly mounted on the fuselage 4. The bottom end of the servo rocker arm 22 is fixedly connected to the output shaft of the rotary power source. The front rocker arm 171 is provided on the front side of the servo rocker arm 22, and the bottom end of the front rocker arm 171 is hinged to 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 servo rocker arm 22. The front rocker arm 171 and the servo rocker arm 22 are of equal length and parallel.

[0009] like Figure 1 、 4 6, the flapping structure 1 is mounted 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, and the lower parts of the side link 151 and the side link 2 152 are respectively hinged to the left and right sides of the frame 17, and the lower parts of the side link 151 and the side link 2 152 have mounting ends extending outside the frame 17; the top ends of the upper link 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 151 and the side link 2 152, and the linear reciprocating power source is installed on the frame 17, and the linear reciprocating power source drives the top ends of the upper link 131 and the upper link 2 132 to reciprocate up and down;

[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] Furthermore, 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 to the fuselage 4. The second front rocker arm 172 is provided on the front side of the fuselage rocker arm 24, and the bottom end of the second front rocker arm 172 is hinged to the fuselage 4. The front and rear ends of the second translation link 232 are respectively hinged to the top end of the second front rocker arm 172 and the top end of the fuselage rocker arm 24. 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 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 springs are fixedly connected to the upper connecting rod 131 and the upper connecting rod 2 132 respectively. The spring 161 and the spring 2 162 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 to the top end 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. A distance 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 portion, 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 at any moment of wing motion, 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. These 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] Where, in is the cam rotation angle at any time, ω is the cam rotation angular velocity, 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, and the rectangular frame 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 cam in the push section is:

[0025]

[0026] In the formula θ1∈[0,π];

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

[0028]

[0029] Where, 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 and near-rest segment φ S The cam profile of ′ is a circular arc segment:

[0031]

[0032] Solving equations (3) to (6) in sequence can obtain the contour curve of the equal-width cam.

[0033] The present invention proposes to replace the gear transmission mechanism with a cam mechanism, which has the following beneficial effects:

[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, making 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 required motion law, which is crucial for the flight control of the aircraft, helps to reduce weight and improve flight efficiency, and ensure the stable flight of the aircraft in complex environments.

[0036] The flapping structure of the present invention recreates the flapping motion of flapping-wing flying animals in nature, especially the indirect (direct) movement of the thorax of insects that controls the flapping of their wings during flight. Specifically, when the rectangular frame push rod moves downward, the flapping wing flaps upward, and the spring is compressed. When the rectangular frame push rod moves upward, the flapping wing flaps downward, and the spring is stretched. Furthermore, when the flapping structure of the present invention is mounted on the fuselage as an integral flapping module of a flapping-wing aircraft, it can tilt at a small angle around the axis of the wing leading edge rod (i.e., the y-axis defined in the figure) under the drive of an external servo, thereby changing the wing plane angle, that is, changing the wing plane of the flapping-wing aircraft. The flapping module can also be expanded in series, i.e., becoming a pair of or multiple pairs of wings. Therefore, the present invention has a strong biomimetic nature and can be widely used in the field of flapping-wing aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0039] Figure 3 It is a structural schematic diagram 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 This is a schematic diagram of the medium-width cam profile curve of the present invention;

[0042] Figure 6 Schematic diagram of the flapping wing control mechanism of the present invention;

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

[0044] Figure 8 Schematic diagram of 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 drive 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 servo, 22 servo rocker arm, 231 translation link 1, 232 translation link 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 described in detail below through specific implementation methods 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. 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 servo rocker arm 22, a translation link 231, and a front rocker arm 171. The rotary power source is fixedly mounted on the fuselage 4. The bottom end of the servo rocker arm 22 is fixedly connected to the output shaft of the rotary power source. The front rocker arm 171 is provided on the front side of the servo rocker arm 22, and the bottom end of the front rocker arm 171 is hinged to 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 servo rocker arm 22. The front rocker arm 171 and the servo rocker arm 22 are of equal length and parallel.

[0053] In order to maintain the stability of the forward and backward pitching movement, 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 to the fuselage 4. The second front rocker arm 172 is provided on the front side of the fuselage rocker arm 24, and the bottom end of the second front rocker arm 172 is hinged to the fuselage 4. The front and rear ends of the second translation link 232 are respectively hinged to the top end of the second front rocker arm 172 and the top end of the fuselage rocker arm 24. 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 rotational power source is a steering gear 21 .

[0056] like Figure 1 、 4 6, the flapping structure 1 is mounted 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 2 172. The lower parts of the side link 151 and the side link 2 152 are respectively hinged to the left and right sides of the frame 17, and the lower parts of the side link 151 and the side link 2 152 have mounting ends extending outside the frame 17. The top ends of the upper link 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 151 and the side link 2 152. The linear reciprocating power source is installed on the frame 17, and the linear reciprocating power source drives the top ends of the upper link 131 and the upper link 2 132 to reciprocate up and down.

[0059] A pair of flapping wings 3 are symmetrically arranged on either side of the frame 17, with their bases fixedly connected to the mounting ends of side link 151 and side link 2 152. Thus, as the linear reciprocating power source drives the top ends of upper link 131 and upper link 2 132 back and forth, it also causes side link 151 and side link 2 152 to rotate, thereby driving the pair of flapping wings 3 to flap up and down. Furthermore, driven by the rotational power source, the flapping structure 1 can drive the translational link, thereby causing the flapping structure to flip forward and backward. Ultimately, by combining the up and down reciprocating motion and the back and forth flipping motion, a complex motion simulating the flapping of an insect's wings can be achieved.

[0060] The flapping structure 1 also includes a spring 161 and a spring 162. The bottom ends of the springs 161 and 162 are fixedly connected to the frame 17, and their top ends are fixedly connected to the upper connecting rod 131 and the upper connecting rod 2 132, respectively. The springs 161 and 162 are symmetrically arranged along the center of the frame 17 and are both vertically positioned. When the flapping wing 3 is stationary, the springs 161 and 162 are in their original state. When the flapping wing 3 flaps upward, the springs 161 and 162 are in a compressed state. When the flapping wing 3 flaps downward, the springs 161 and 162 are in a stretched state. In this way, the springs effectively assist and amplify the linear power source during 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 to the top end 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 distance 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 portion, 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. 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. Its equal width is a limit frame, that is, the cam is only allowed to move within 180°. The remaining 180° must be "mirror" symmetrical to the first 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 a 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, 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. Further, according to the follower push rod motion equation in the equal-width cam mechanism design criteria, the displacement law curve of the push rod following the cam rotation angle within one cycle is drawn, and finally the contour curve of the cam is designed based on 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 are equal. 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 principle of equal width, which is similar to the motion law of the push section. Therefore, when designing a constant 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] Previous animal flight experiments have found that the kinematic equations for the periodic flapping of flapping wings can be expressed using Fourier series. Therefore, the up-and-down flapping motion equation for wings can be expressed as:

[0065]

[0066] Where α(t) is the flapping angle of the wings at any moment, t is time, A0, A n , δ n (n=1,2,3,…) are Fourier coefficients, 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 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. These 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] Where, in is the cam rotation angle at any time, ω is the cam rotation angular velocity, 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, and the rectangular frame 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] Where, 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 and near-rest segment φ S The cam profile of ′ is an arc segment

[0080]

[0081] Solving equations (3) to (6) in sequence can obtain the contour curve of the equal-width cam.

[0082] There are many specific implementation ways of the present invention. The above is only the preferred implementation method 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 principles of the present invention. These improvements should also be considered as the scope of protection 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 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. The flapping structure (1) is mounted on the fuselage (4) and connected to the front rocker arm (171); The flapping structure (1) includes a frame (17), a linear reciprocating power source, 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 thereof are fixedly connected to the mounting ends of the side connecting rod 1 (151) and the side connecting rod 2 (152); 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 to the top ends of the upper connecting rod 1 (131) and the 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 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 portion, and the guide rod passes through the frame (17).

2. The flapping-wing drive mechanism of a bionic flapping-wing aircraft according to claim 1, characterized in that: The flapping wing control mechanism (2) further comprises 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 to 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 to the fuselage (4), the front and rear ends of the second translation link (232) are respectively hinged to 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 (231) and the second translation link (232) are of equal length and parallel.

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

4. The flapping-wing drive 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. A method for designing a medium-width cam in a flapping-wing drive mechanism of a bionic flapping-wing aircraft according to claim 4, characterized in that: The up and down flapping motion of the flapping wing (3) can be expressed by the equation when n=1: α(t)=A0+A1sin(ωt+δ1) (1) Where α(t) is the flapping angle value at any moment of wing motion, 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: Where, in is the cam rotation angle at any time, ω is the cam rotation angular velocity, 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 profile vector equation of the cam in polar coordinates. Among them, the profile vector equation of the cam in the push-stroke section is: In the formula θ1∈[0,π]; The vector equation of the cam profile in the return section is: Where, 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 and near-rest segment φ S The cam profile of ′ is a circular arc segment: Solving equations (3) to (6) in sequence can obtain the contour curve of the equal-width cam.

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