Bionic mechanical dragonfly aircraft based on flapping frequency modulation and its control method

Abstract

The present invention relates to a bionic mechanical dragonfly aircraft based on flapping frequency modulation and a control method thereof. The aircraft comprises a frame, four wings, and four wing drive mechanisms; the wing drive mechanisms comprise a motor, a belt drive mechanism, and a swing guide rod mechanism; the belt drive mechanism comprises a first pulley and a second pulley coupled via a transmission belt; the first pulley is connected to the motor; the second pulley is provided with a crank; the swing guide rod mechanism comprises a guide rod coupled to the wing; the guide rod is provided with a guide rail corresponding to the crank; driven by the motor, the first pulley rotates, which in turn drives the second pulley to rotate via the transmission belt. The crank and the guide rail cooperate to convert the rotation of the second pulley into the swing of the guide rod, thereby driving the movement of the wings connected to the guide rod. The present invention proposes a method of using a flapping stroke centerline offset and a flapping stroke velocity offset to enable each wing to produce four-dimensional effects of yaw, pitch, roll, and lift through frequency modulation.

Description

Technical Field

[0001] The present invention relates to the technical field of micro air vehicles, and in particular to a bionic mechanical dragonfly aircraft based on flapping frequency modulation and a control method thereof. Background Art

[0002] The concept of micro air vehicles was proposed and defined by the U.S. Defense Advanced Research Projects Agency in 1992. Micro air vehicles have a wingspan of no more than 15 cm, weigh between 10-100 grams, can fly continuously for 20-60 minutes, have a controllable radius greater than 10 kilometers, and can carry a load of 20g. They can fly autonomously at a speed of between 1-10m / s and can transmit captured images to a ground station in real time. Their Reynolds number is below 106. The micro air vehicles currently under development and in use mainly include fixed-wing aircraft, rotorcraft, and flapping-wing aircraft. Fixed-wing aircraft cannot hover and cannot be made very small; rotorcraft are easily affected by external interference, have poor wind resistance, are noisy, and have poor concealment; flapping-wing aircraft have better maneuverability, can be made smaller, and have a greater advantage in concealment.

[0003] The key features of flapping-wing micro-aircraft are their ability to achieve lift, hover, and free-flight turns. Free-flight turns, or flight attitude changes, are both a key technical focus and a significant challenge for flapping-wing aircraft. To achieve optimal miniaturization, most current flapping-wing micro-aircraft use flapping wings to generate control torque. There are two main technical approaches: one employs a manipulator to adjust the flexible wing shape or the flapping angle of attack to achieve control; the other employs piezoelectric or servo motors to directly drive the wings and modulate the flapping stroke to achieve control. Limited by structural and theoretical limitations, existing flapping-wing micro-aircraft suffer from complex mechanical structures and high control difficulty. Micro-aircraft that use flapping wings to generate control torque achieve flight attitude changes by manipulating the flapping frequency, flexible wing shape, flapping stroke centerline, and flapping stroke plane to alter the magnitude, point of application, and direction of the flapping aerodynamic force. Both technical approaches for implementing these control mechanisms present unresolved structural and theoretical challenges. Flapping-wing aircraft employing additional control mechanisms require additional mechanical components, resulting in a complex mechanical structure that reduces aircraft reliability. Furthermore, the increased weight of the control mechanism reduces the aircraft's payload capacity and flight time. Flapping-wing aircraft employing piezoelectric materials or direct motor drive combined with flapping stroke modulation lack an indirect drive mechanism, making control more complex and technically challenging. This complexity also reduces aircraft reliability. In addition to these unavoidable drawbacks, the control torque generated by altering the flapping wing's aerodynamic forces can produce cross-coupling effects. This means that altering the flapping wing's aerodynamic forces generates torques for all three attitude transformations. To mitigate this cross-coupling effect, aircraft employ hybrid control systems or complex control laws to mitigate the coupling. The former requires complex mechanical structures, reducing aircraft reliability, increasing overall weight, and reducing payload capacity. The latter offers complex control laws, making them difficult to implement and reducing aircraft reliability. Summary of the Invention

[0004] In order to address the deficiencies in the prior art, the present invention aims to provide a bionic mechanical dragonfly aircraft based on flapping frequency modulation and a control method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect of the present invention, a biomimetic mechanical dragonfly aircraft based on flapping frequency modulation is disclosed.

[0007] Specifically, the aircraft includes a frame, four wings symmetrically distributed on both sides of the frame, and four wing drive mechanisms arranged in a one-to-one correspondence with the four wings;

[0008] The wing drive mechanism includes a motor, a belt transmission mechanism and a swing guide rod mechanism;

[0009] The belt transmission mechanism includes a first pulley and a second pulley that are coupled together by a transmission belt; the first pulley is connected to the motor; and a crank is provided on the second pulley;

[0010] The swing guide rod mechanism includes a guide rod connected to the wing; the guide rod is provided with a guide rail corresponding to the rocker;

[0011] Driven by the motor, the first pulley rotates, driving the second pulley to rotate through the transmission belt. Through the cooperation of the crank handle and the guide rail, the rotation of the second pulley is converted into the swing of the guide rod, thereby driving the movement of the wing connected to the guide rod.

[0012] Furthermore, the frame includes a first supporting portion, a second supporting portion, and a third supporting portion connected between the first supporting portion and the middle section of the second supporting portion;

[0013] The first supporting portion and the second supporting portion are both provided with a first pulley mounting shaft hole, a second pulley mounting shaft hole and a guide rod mounting shaft hole;

[0014] Four motor mounting components are provided on the third supporting portion.

[0015] Furthermore, the second pulley is mounted on the frame via a first rotating shaft;

[0016] The guide rod is mounted on the frame via a second rotating shaft.

[0017] Furthermore, the wings are mounted on the guide rod via a connecting shaft;

[0018] The wing is provided with a first connecting shaft hole;

[0019] The guide rod is provided with a second connecting shaft hole and a wing connecting hole;

[0020] The connecting shaft passes through the first connecting shaft hole and the second connecting shaft hole and is interference fit with the two connecting shaft holes;

[0021] The guide rod is connected to the wing through the wing connecting hole and the connecting shaft.

[0022] Furthermore, the first pulley includes a first pulley body, a first pulley groove provided on the outer periphery of the middle section of the first pulley body, and a first mounting shaft hole provided in the middle of the first pulley body;

[0023] The first pulley cooperates with the transmission belt through the first pulley groove, the second pulley cooperates with the transmission belt through the second pulley groove, and transmits rotation;

[0024] The output shaft of the motor is interference-fitted with the first mounting shaft hole and has a clearance fit with the first pulley mounting shaft hole.

[0025] Furthermore, the second pulley includes a second pulley body, a second pulley groove provided on the outer periphery of the middle section of the second pulley body, and a second mounting shaft hole provided in the middle of the second pulley body;

[0026] The crank handle is arranged on the end surface of the second pulley body;

[0027] The second pulley is mounted on the frame through the second mounting shaft hole, the first mounting shaft hole and the first rotating shaft are clearance-fitted, and the first rotating shaft and the second pulley mounting shaft hole are interference-fitted;

[0028] The second pulley acts as a crank in the swing guide rod mechanism, and the rocker on it rotates a full circle. While rotating, the rocker moves relative to the guide rail of the guide rod, causing the guide rod to swing.

[0029] Furthermore, the guide rod includes a guide rod body and a third mounting shaft hole provided on the guide rod body;

[0030] The guide rail is arranged on the guide rod body;

[0031] The third mounting shaft hole on the guide rod is clearance-fitted with the second rotating shaft, and the second rotating shaft is mounted on the frame through interference fit with the mounting shaft hole of the guide rod.

[0032] Furthermore, the wing includes a wing frame surrounded by a leading edge and a trailing edge, and a wing membrane installed in the middle of the wing frame;

[0033] The wing frame is provided with a third connecting shaft hole.

[0034] In a second aspect of the present invention, a method for controlling the above-mentioned aircraft is disclosed.

[0035] S1, Roll

[0036] The wings and motors are divided into left and right sides, the motor frequency on one side is increased and the frequency of the motor on the other side is reduced synchronously. The attitude torque of the two wings on the side where the motor frequency increases increases, and the attitude torque of the two wings on the side where the motor frequency decreases decreases. The pitching moment and yaw moment generated by the four wings cancel each other out. At the same time, the generated rolling moments are superimposed on the center of mass to produce a clockwise rolling moment, and the aircraft rolls toward the side where the motor frequency decreases.

[0037] Specifically, by increasing the frequency of the left motor and synchronously decreasing the frequency of the right motor, the attitude torque of the left forewing and left hind wing increases, and the attitude torque of the right forewing and right hind wing decreases, and the pitch moment and yaw moment generated by the four wings cancel each other out. At the same time, the generated rolling moments are superimposed on the center of mass to generate a counterclockwise rolling moment, and the aircraft rolls to the right; by decreasing the frequency of the left motor and synchronously increasing the frequency of the right motor, the attitude torque of the left forewing and left hind wing decreases, and the attitude torque of the right forewing and right hind wing increases, and the pitch moment and yaw moment generated by the four wings cancel each other out. At the same time, the generated rolling moments are superimposed on the center of mass to generate a clockwise rolling moment, and the aircraft rolls to the left.

[0038] S2, pitch

[0039] The wings and motors are divided into the front and rear sides, the motor frequency on one side is increased and the motor frequency on the other side is reduced synchronously. The attitude torque of the two wings on the side where the motor frequency increases increases, and the attitude torque of the two wings on the side where the motor frequency decreases decreases. The rolling moment and yaw moment generated by the four wings cancel each other out. At the same time, the pitching moment generated is superimposed on the center of mass to produce a counterclockwise pitching moment, and the aircraft pitches.

[0040] Specifically, when the front motor frequency is increased and the rear motor frequency is simultaneously decreased, the attitude torques of the left and right forewings increase, while those of the left and right hindwings decrease. The rolling and yaw moments generated by the four wings cancel each other out. At the same time, the resulting pitching moments are superimposed on the center of mass to produce a clockwise pitching moment, causing the aircraft to tilt its head upward. When the front motor frequency is decreased and the rear motor frequency is simultaneously increased, the attitude torques of the left and right forewings decrease, while those of the left and right hindwings increase. The rolling and yaw moments generated by the four wings cancel each other out. At the same time, the resulting pitching moments are superimposed on the center of mass to produce a counterclockwise pitching moment, causing the aircraft to tilt its head downward.

[0041] S3, Yaw

[0042] By increasing the frequency of the two motors on one diagonal of the frame and synchronously reducing the frequency of the two motors on the other diagonal, the attitude torque of the wing corresponding to the motor with increased frequency increases, and the attitude torque of the wing corresponding to the motor with reduced frequency decreases. The rolling moment and pitching moment generated by the four wings cancel each other out. At the same time, the generated yaw moment is superimposed on the center of mass to produce a clockwise yaw moment, causing the aircraft to yaw.

[0043] Specifically, when the frequencies of the left front and right rear motors are increased and the frequencies of the opposite motors are simultaneously decreased, the attitude torques of the left front and rear wings increase, while the attitude torques of the right front and left rear wings decrease. The rolling and pitching moments generated by the four wings cancel each other out. At the same time, the resulting yaw moments are superimposed on the center of mass to produce a clockwise yaw moment, causing the aircraft to yaw to the right. When the frequencies of the left front and right rear motors are decreased and the frequencies of the opposite motors are simultaneously increased, the attitude torques of the left front and rear wings decrease, while the attitude torques of the right front and left rear wings increase. The rolling and pitching moments generated by the four wings cancel each other out. At the same time, the resulting yaw moments are superimposed on the center of mass to produce a counterclockwise yaw moment, causing the aircraft to yaw to the left.

[0044] S4, lifting

[0045] By adjusting the frequency of the four motors, the lift generated by the four wings changes, and the aircraft takes off and up actions.

[0046] Specifically, by increasing the frequency of the four motors, the lift generated by the four wings increases to a point where it exceeds the combined force of drag and gravity, causing the aircraft to fly upward. By decreasing the frequency of the four motors, the lift generated by the four wings decreases to a point where it is less than the combined force of drag and gravity, causing the aircraft to descend. During this process, the aerodynamic torques generated by the wings cancel each other out, preventing interference.

[0047] Furthermore, the method further comprises:

[0048] By adjusting the motor frequency, the left forewing generates a counterclockwise rolling moment, a clockwise pitching moment, and a clockwise yaw moment; the right forewing generates a clockwise rolling moment, a clockwise pitching moment, and a counterclockwise yaw moment; the right hindwing generates a clockwise rolling moment, a counterclockwise pitching moment, and a clockwise yaw moment; and the left hindwing generates a counterclockwise rolling moment, a counterclockwise pitching moment, and a counterclockwise yaw moment.

[0049] Compared with the prior art, the advantages of the present invention are:

[0050] (1) The present invention proposes a tandem double-wing biomimetic mechanical dragonfly aircraft with a symmetrical offset structural layout based on the cross-coupling effect of flapping wing aerodynamics. The aircraft adopts a belt drive and a swinging guide rod mechanism as the transmission mechanism, and the second pulley of the belt drive also serves as the crank mechanism in the swinging guide rod mechanism; the transmission structure is simple, the number of parts is small, and it is easy to achieve miniaturization and lightweight. Through mechanical structure design, the crank rotation center and the guide rod swing center of the swinging guide rod mechanism are offset, so that the center line of the flapping wing flapping stroke is offset; at the same time, by designing the size of the swinging guide rod mechanism and controlling its quick return characteristics, the flapping speed curve of the flapping wing flapping stroke is symmetrically offset. The offset of the flapping stroke center line and the offset of the flapping stroke speed curve enable the aircraft to superimpose and enhance the required target torque in the aerodynamic control torque coupling, and symmetrically offset the unnecessary torque, thereby achieving good attitude change only through frequency modulation.

[0051] (2) The aircraft described in the present invention does not require additional control mechanisms and servos, and the entire weight of the aircraft is used to generate lift, thereby improving the carrying capacity of the aircraft and increasing its hovering time. At the same time, the aircraft uses a mechanical structure transmission to control the flapping of the wings instead of directly driving the wings with a motor. The control is direct and easy to implement, and the serial layout can be used to unify hovering and level flight.

[0052] (3) Based on the cross-coupling effect of aerodynamic torque, the present invention proposes a set of bionic mechanical dragonfly aircraft control strategies, which can realize lifting and free flight turning movements, achieve miniaturization and have good maneuverability. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic diagram of the overall structure of the bionic mechanical dragonfly aircraft of the present invention;

[0054] Figure 2 This is a schematic diagram of the fuselage structure of the bionic mechanical dragonfly aircraft of the present invention;

[0055] Figure 3a This is a schematic structural diagram of the transmission mechanism of the bionic mechanical dragonfly aircraft of the present invention;

[0056] Figure 3b This is a schematic diagram of the structure of the motor in the bionic mechanical dragonfly aircraft of the present invention;

[0057] Figure 3c This is a schematic structural diagram of the first pulley in the bionic mechanical dragonfly aircraft of the present invention;

[0058] Figure 3d This is a schematic structural diagram of the second pulley in the bionic mechanical dragonfly aircraft of the present invention;

[0059] Figure 3eThis is a schematic structural diagram of the guide rod in the bionic mechanical dragonfly aircraft of the present invention;

[0060] Figure 3f This is a schematic diagram of the structure of the wings of the bionic mechanical dragonfly aircraft of the present invention;

[0061] Figure 4 It is a front view of the front wing flapping mechanism of the bionic mechanical dragonfly aircraft of the present invention and a schematic diagram of the mechanism movement;

[0062] Figure 5 This is a front view of the rear wing flapping mechanism and a schematic diagram of the mechanism movement in the bionic mechanical dragonfly aircraft of the present invention;

[0063] Figure 6a This is a schematic diagram of the roll adjustment of the bionic mechanical dragonfly aircraft of the present invention;

[0064] Figure 6b This is a schematic diagram of pitch adjustment of the bionic mechanical dragonfly aircraft of the present invention;

[0065] Figure 6c This is a schematic diagram of the yaw adjustment of the bionic mechanical dragonfly aircraft of the present invention;

[0066] Figure 6d It is a schematic diagram of the lifting and lowering adjustment of the bionic mechanical dragonfly aircraft in the present invention. DETAILED DESCRIPTION

[0067] The present invention will be further described below with reference to the accompanying drawings:

[0068] Current micro-aircraft primarily utilize flapping wings to generate control torque. This approach primarily involves adding additional control mechanisms to adjust the wing's attitude, thereby altering the aerodynamic forces and generating control torque. This additional control mechanism not only increases the mass and size of the aircraft but also reduces its reliability. Furthermore, the use of flapping wings to generate control torque introduces a cross-coupling effect: altering the flapping wing's aerodynamic forces will generate control torque for all three attitude transformations. Existing solutions involve decoupling these mechanisms or employing complex control laws for corrective control.

[0069] In response to the above two points, the present invention proposes a tandem double-wing biomimetic mechanical dragonfly aircraft with a symmetrical offset structural layout based on the cross-coupling effect of flapping wing aerodynamics. The control torque generated by each wing is adjusted by the offset of the centerline of the flapping stroke and the different speeds of different flapping strokes, and the attitude change of the aircraft is further achieved only by frequency modulation. The bionic four-wing aircraft does not require additional control mechanisms to achieve attitude change. All mass is used to generate lift by the flapping of the wings. Its mechanical structure is simple and the overall efficiency is higher. At the same time, a corresponding control strategy is proposed based on the coupling effect of aerodynamic torque, which can realize attitude change of four degrees of freedom: roll, pitch, yaw and lift, achieving miniaturization while having good maneuverability.

[0070] The present invention proposes a bionic mechanical dragonfly aircraft that controls flight motion based on flapping frequency modulation and can achieve multiple flight modes such as level flight, gliding, and hovering, and proposes a corresponding control method. The bionic mechanical dragonfly aircraft that controls flight motion based on frequency modulation adopts a serial double-pair wing configuration with a symmetrical offset structural layout, uses a swinging guide rod mechanism to achieve wing flapping, and realizes aerodynamic control torque coupling through the offset of the flapping stroke centerline and the speed difference of different strokes of the flapping stroke, so that the required target torque is superimposed and enhanced, and the unnecessary torque is symmetrically offset, thereby achieving good attitude transformation only through frequency modulation. The control method is a set of bionic mechanical dragonfly aircraft control strategies based on the coupling effect of aerodynamic torque, which can realize lifting and free flight turning movements, that is, realizing attitude transformation of four degrees of freedom roll, pitch, yaw and lifting through frequency modulation.

[0071] like Figure 1 As shown, the quadcopter proposed in the present invention mainly includes: a frame 1-5, four groups of motors 1-1a, 1-1b, 1-1c, and 1-1d installed on the frame 1-5, four groups of belt transmission mechanisms 1-2a, 1-2b, 1-2c, and 1-2d, four groups of swing guide rod mechanisms 1-3a, 1-3b, 1-3c, and 1-3d, and four groups of wings 1-4a, 1-4b, 1-4c, and 1-4d.

[0072] like Figure 2 As shown, there are four motor mounting components 2-1a, 2-1b, 2-1c, and 2-1d on the frame 1-5, four first pulley mounting shaft holes 2-2a, 2-2b, 2-2c, and 2-2d, four second pulley mounting shaft holes 2-3a, 2-3b, 2-3c, and 2-3d, and four guide rod mounting shaft holes 2-4a, 2-4b, 2-4c, and 2-4d.

[0073] like Figure 3aAs shown, the transmission component mainly consists of a belt drive mechanism and a swing guide rod mechanism. Power is provided by motor 1-1, which rotates the first pulley 3-1. This is then transmitted via a transmission belt 3-2, which in turn rotates the second pulley 3-3. The second pulley 3-3 also acts as a crank in the swing guide rod mechanism, converting the rotation of the second pulley 3-3 into the swing of the guide rod 3-4. The second pulley is mounted on the frame via a first rotating shaft 3-5, and the guide rod 3-4 is mounted on the frame via a second rotating shaft 3-6. The wing is mounted on the guide rod 3-4 via a connecting shaft 3-7, which passes through the wing's connecting shaft hole 1-4-1 and the guide rod's second connecting shaft hole 3-4-3, forming an interference fit therewith.

[0074] like Figure 3b As shown, the motor 1-1 is composed of a main body 1-1-2 and a motor output shaft 1-1-1. Figure 3c As shown, the first pulley 3-1 is mainly composed of a first mounting shaft hole 3-1-1 and a first pulley groove 3-1-2. Figure 3d As shown, the second pulley 3-3 mainly features a second mounting shaft hole 3-3-1, a second pulley groove 3-3-3 and a crank handle 3-3-2. Figure 3e As shown, the guide rod 3-4 is mainly composed of a second connecting shaft hole 3-4-1, a wing connecting hole 3-4-3 and a guide rail 3-4-2.

[0075] The motor output shaft 1-1-1 and the first pulley shaft hole 3-1-1 have an interference fit, and Figure 2 The first pulley mounting shaft hole 2-2 on the middle frame is in clearance fit. The first pulley 3-1 and the second pulley 3-3 are respectively fitted with the transmission belt 3-2 through the first pulley groove 3-1-2 and the second pulley groove 3-3-3 to transmit rotation. The second pulley 3-3 is mounted on the frame through the second mounting shaft hole 3-3-1. The second pulley shaft hole 3-3-1 is in clearance fit with the first rotating shaft 3-5. The first rotating shaft 3-5 and Figure 2 The second pulley mounting shaft hole 2-3 on the middle frame is interference fit. The second pulley 3-3 also acts as the crank in the swing guide rod mechanism. The crank handle 3-3-2 on it rotates a full circle. While rotating, the crank handle 3-3-2 moves relative to the guide rail 3-4-2 of the guide rod 3-4, causing the guide rod 3-4 to swing. The second connecting shaft hole 3-4-1 of the guide rod has a clearance fit with the second rotating shaft 3-6. The second rotating shaft 3-6 is connected to the second connecting shaft 3-6. Figure 2 The guide rod mounting shaft hole 2-4 on the middle frame is installed on the frame through interference fit. The guide rod 3-4 is connected to the wing 1-4 through the wing connecting hole 3-4-3 and the connecting shaft 3-7.

[0076] like Figure 3f As shown, the wing 1-4 mainly includes a first connecting shaft hole 1-4-1, a leading edge 1-4-2, a trailing edge 1-4-3 and a wing membrane 1-4-4.

[0077] Based on a flapping mechanism composed of a belt transmission mechanism and a swing guide rod mechanism, the present invention proposes a mechanical structure that enables the center lines of the flapping strokes of the front and rear wings of an aircraft to be symmetrically offset. Figure 4 Shown is a front view and a simplified diagram of the flapping mechanism for the front wings, namely wings 1-4a and 1-4b. In the diagram, 4-1a and 4-1b represent the first pulley 3-1, 4-2a and 4-2b represent the transmission belt 3-2, 4-3a and 4-3b represent the second pulley 3-3, 4-4a and 4-4b represent the crank handle 3-3-2, 4-5a and 4-5b represent the guide rail 3-4-2, 4-6a and 4-6b represent the guide rod 3-4, 4-8a and 4-8b represent wings 1-4a and 1-4b, and 4-7a and 4-7b represent the centerlines of the flapping stroke of wings 1-4a and 1-4b, respectively.

[0078] For the flapping mechanism of the wing 1-4a, the first pulley 4-1a is driven by the motor 1-1 as follows Figure 4 The arrow on the top rotates counterclockwise at a constant speed, and the transmission belt 4-2a is used to transmit the power to the second pulley 4-3a. Figure 4 The upper arrow indicates counterclockwise rotation, and the crank handle 4-4a on the second pulley 4-3a is loosely fitted with the guide rail 4-5a. As the crank handle 4-4a rotates counterclockwise, it slides relative to the guide rail 4-5a, causing the guide rod 4-6a to swing and the wing 4-8a to flap. When the crank handle 4-4a rotates counterclockwise from the solid line position in the figure to the dashed line position, the wing 4-8a flaps upward from the lower limit position to the upper limit position. Continuing counterclockwise rotation, the crank handle 4-4a rotates from the dashed line position to the solid line position, causing the wing 4-8a to flap downward from the upper limit position to the lower limit position. The flapping mechanism completes one flapping cycle, and during this flapping cycle, the average speed of the wing 4-8a during the downward flapping stroke is greater than the average speed during the upward flapping stroke.

[0079] The flapping mechanism of wing 1-4b is symmetrically mounted to the flapping mechanism of wing 1-4a. Clockwise rotation of first pulley 4-1b drives clockwise rotation of second pulley 4-3b and crank handle 4-4b thereon. Relative sliding of crank handle 4-4b and guide rail 4-5b causes guide rod 4-6b to swing, driving wing 4-8b to flap. When crank handle 4-4b rotates from the solid line position to the dashed line position, wing 4-8b flaps upward from the lower limit position to the upper limit position. Further rotation of crank handle 4-4b from the dashed line position to the solid line position causes wing 4-8b to flap downward from the upper limit position to the lower limit position, completing a flapping cycle. The average speed of wing 4-8b during its downward flapping stroke is greater than its average speed during its upward flapping stroke.

[0080] The average speed of the downward stroke is greater than the average speed of the upward stroke, which will cause wings 1-4a and 1-4b to generate forward thrust, which will cause wing 1-4a to generate a clockwise yaw moment around the yaw axis and wing 1-4b to generate a counterclockwise yaw moment around the yaw axis.

[0081] like Figure 4 As shown, the belt drive centerline is offset downward by an angle relative to the pitch axis, that is, the rotation center of the second pulleys 4-3a and 4-3b is offset downward relative to the pitch axis; the rotation center of the guide rods 4-5a and 4-5b is offset upward relative to the pitch axis. The offset of the mechanical mechanism makes the flapping stroke centerlines 4-7a and 4-7b of the wings 4-8a and 4-8b as shown in FIG. Figure 4 The offset of the centerline of the flapping stroke causes the point of action of the aerodynamic force generated by the flapping of wings 1-4a and 1-4b to shift upward, causing wings 1-4a and 1-4b to generate a clockwise pitching moment about the pitch axis.

[0082] In addition, wings 1-4a and wings 1-4b are arranged symmetrically with respect to the roll axis, so that the lift of wings 1-4a generates a counterclockwise rolling moment around the roll axis, and the lift of wings 1-4b generates a clockwise rolling moment around the roll axis.

[0083] Figure 5 Shown is a front view and simplified diagram of the flapping mechanism for the rear wings, namely wings 1-4c and 1-4d. Components 5-1c and 5-1d represent the first pulley 3-1, 5-2c and 5-2d represent the drive belt 3-2, 5-3c and 5-3d represent the second pulley 3-3, 5-4c and 5-4d represent the crank handle 3-3-2, 5-5c and 5-5d represent the guide rail 3-4-2, 5-6c and 5-6d represent the guide rod 3-4, 5-8c and 5-8d represent wings 1-4c and 1-4d, and 5-7c and 5-7d represent the centerlines of the flapping stroke of wings 1-4c and 1-4d, respectively.

[0084] For the flapping mechanism of the wing 1-4c, the first pulley 5-1c is driven by the motor 1-1 as follows Figure 5 The arrow on the top rotates counterclockwise at a constant speed, and the transmission belt 5-2c is used to transmit the power to the second pulley 5-3c and the crank 5-4c on it. Figure 5 The upper arrow indicates counterclockwise rotation, and the crank 5-4c on the second pulley 5-3c is in clearance with the guide rail 5-5c. When the crank 5-4c rotates counterclockwise, it slides relative to the guide rail 5-5c, causing the guide rod 5-6c to swing and drive the wing 5-8c to flap. Figure 5 The middle solid line position rotates counterclockwise to the dotted line position, causing wings 5-8c to flap downward from their upper limit position to their lower limit position. Continuing to rotate counterclockwise, the crank handle 5-4c rotates from the dotted line position to the solid line position, causing wings 5-8c to flap upward from their lower limit position to their upper limit position. In this way, the flapping mechanism completes one flapping cycle, and during this flapping cycle, the average speed of the wings 4-8c during the downward flapping stroke is less than the average speed during the upward flapping stroke.

[0085] The flapping mechanism of wing 1-4d is symmetrically mounted to the flapping mechanism of wing 1-4c. Clockwise rotation of first pulley 5-1d drives clockwise rotation of second pulley 5-3d and crank handle 5-4d thereon. Relative sliding of crank handle 5-4d and guide rail 5-5d causes guide rod 5-6d to swing, driving wing 5-8d to flap. When crank handle 5-4d rotates from the solid line position to the dashed line position, wing 5-8d flaps downward from its upper limit position to its lower limit position. Further rotation of crank handle 5-4d from the dashed line position to the solid line position causes wing 5-8d to flap upward from its lower limit position to its upper limit position, completing a flapping cycle. The average speed of wing 5-8d during its downward flapping stroke is less than its average speed during its upward flapping stroke.

[0086] The average speed of the downward stroke is less than the average speed of the upward stroke, which will cause wings 1-4c and 1-4d to generate backward thrust, which will cause wing 1-4c to generate a clockwise yaw moment around the yaw axis and wing 1-4d to generate a counterclockwise yaw moment around the yaw axis.

[0087] like Figure 5 As shown, the belt drive centerline is offset upward by an angle relative to the pitch axis, that is, the rotation center of the second pulleys 5-3c and 5-3d is offset upward relative to the pitch axis; the rotation center of the guide rods 5-5c and 5-5d is offset downward relative to the pitch axis. The offset of the mechanical mechanism makes the flapping stroke centerlines 5-7c and 5-7d of the wings 5-8c and 5-8d as shown in FIG. Figure 5 The arrow in the middle indicates an angle downward.

[0088] The downward shift in the flapping stroke centerline shifts the point of action of the aerodynamic forces generated by the flapping of wings 1-4c and 1-4d downward, causing wings 1-4c and 1-4d to generate a counterclockwise pitching moment about the pitch axis. Furthermore, wings 1-4c and 1-4d are arranged symmetrically about the roll axis, so that the lift of wing 1-4c generates a clockwise rolling moment about the roll axis, while the lift of wing 1-4d generates a counterclockwise rolling moment about the roll axis.

[0089] The present invention proposes a serial double-pair-wing bionic mechanical dragonfly aircraft with a symmetrical offset structural layout, which uses the method of flapping stroke centerline offset and flapping stroke speed offset, so that each wing can produce four-dimensional effects of yaw, pitch, roll and lift through frequency modulation.

[0090] Define the power that generates counterclockwise aerodynamic torque and lift as positive; define the positive direction of the roll axis as the nose of the bionic quadcopter, and the yaw axis as the opposite direction of gravity of the bionic quadcopter; the positive direction of the roll axis is forward, and the negative direction is backward; the positive direction of the pitch axis is left, and the negative direction is right; the positive direction of the yaw axis is up, and the negative direction is down.

[0091] From the above discussion, the aerodynamic effect of the aircraft wing is:

[0092] The aerodynamic force of wing 1-4a generates a counterclockwise rolling moment around the roll axis, causing the aircraft to roll to the right, a clockwise pitching moment around the pitch axis, causing the aircraft to tilt upward, and a clockwise yaw moment around the yaw axis, causing the aircraft to yaw to the right; the aerodynamic force of wing 1-4b generates a clockwise rolling moment around the roll axis, causing the aircraft to roll to the left, a clockwise pitching moment around the pitch axis, causing the aircraft to tilt upward, and a counterclockwise yaw moment around the yaw axis, causing the aircraft to yaw to the left; The aerodynamic force of wing 1-4c generates a clockwise rolling moment around the roll axis, causing the aircraft to roll to the left, a counterclockwise pitching moment around the pitch axis, causing the aircraft to bow its head downward, and a clockwise yaw moment around the yaw axis, causing the aircraft to yaw to the right; the aerodynamic force of wing 1-4d generates a counterclockwise rolling moment around the roll axis, causing the aircraft to roll to the right, a counterclockwise pitching moment around the pitch axis, causing the aircraft to bow its head downward, and a counterclockwise yaw moment around the yaw axis, causing the aircraft to yaw to the left.

[0093] S1, Roll

[0094] like Figure 6a As shown, the speed of the left motor is increased by Δ relative to the average speed ω roll , and simultaneously reduce the speed of the right motor to ω-Δ roll The flapping frequencies of the left wings 1-4a and 1-4d will increase synchronously, while the flapping frequencies of the right wings 1-4b and 1-4c will decrease synchronously. At this time, the aerodynamic forces and aerodynamic moments of wings 1-4a and 1-4d increase, while the aerodynamic forces and aerodynamic moments of wings 1-4b and 1-4c decrease. The nose-up moment generated by wing 1-4a and the nose-down moment generated by wing 1-4d increase synchronously and cancel each other out, the nose-up moment generated by wing 1-4b and the nose-down moment generated by wing 1-4c decrease synchronously and cancel each other out, and the aircraft has no torque on the pitch axis; the right yaw moment generated by wing 1-4a and the left yaw moment generated by wing 1-4d increase synchronously and cancel each other out, the left yaw moment generated by wing 1-4b and the right yaw moment generated by wing 1-4c decrease synchronously and cancel each other out, and the aircraft has no torque on the yaw axis; the right roll moment generated by wings 1-4a and 1-4d increases, and the left roll moment generated by wings 1-4b and 1-4c decreases, and the aircraft generates a right roll moment on the roll axis, which will roll to the right. Conversely, the left motor decreases from the speed ω to ω-Δ roll , the right motor speed increases to ω+Δroll , the flapping frequency of the left wings 1-4a and 1-4d will decrease synchronously, while the flapping frequency of the right wings 1-4b and 1-4c will increase synchronously. At this time, the aerodynamic force and aerodynamic torque of the wings 1-4a and 1-4d decrease, while the aerodynamic force and aerodynamic torque of the wings 1-4b and 1-4c increase. The nose-up moment generated by wing 1-4a and the nose-down moment generated by wing 1-4d decrease synchronously and offset each other, the nose-up moment generated by wing 1-4b and the nose-down moment generated by wing 1-4c increase synchronously and offset each other, and the aircraft has no torque on the pitch axis; the right yaw moment generated by wing 1-4a and the left yaw moment generated by wing 1-4d decrease synchronously and offset each other, the left yaw moment generated by wing 1-4b and the right yaw moment generated by wing 1-4c increase synchronously and offset each other, and the aircraft has no torque on the yaw axis; the right rolling moment generated by wings 1-4a and wing 1-4d decreases, and the left rolling moment generated by wings 1-4b and wing 1-4c increases, and the aircraft generates a left rolling moment on the roll axis, which will roll to the left.

[0095] S2, pitch

[0096] like Figure 6b As shown, the speed of the front motor is increased by Δ relative to the average speed ω. pitch , and simultaneously reduce the speed of the rear motor to ω-Δ pitch , the flapping frequency of the front wings 1-4a and 1-4b will increase synchronously, while the flapping frequency of the rear wings 1-4c and 1-4d will decrease synchronously. At this time, the aerodynamic force and aerodynamic torque of the wings 1-4a and 1-4b increase, while the aerodynamic force and aerodynamic torque of the wings 1-4c and 1-4d decrease. The right rolling moment generated by wing 1-4a and the left rolling moment generated by wing 1-4b increase synchronously and cancel each other out. The left rolling moment generated by wing 1-4c and the right rolling moment generated by wing 1-4d decrease synchronously and cancel each other out. The aircraft has no torque on the roll axis. The right yaw moment generated by wing 1-4a and the left yaw moment generated by wing 1-4b increase synchronously and cancel each other out. The right yaw moment generated by wing 1-4c and the left yaw moment generated by wing 1-4d decrease synchronously and cancel each other out. The aircraft has no torque on the yaw axis. The nose-up moment generated by wings 1-4a and 1-4b increases, while the nose-down moment generated by wings 1-4c and 1-4d decreases. The aircraft generates an upward nose-up moment on the pitch axis, which will tilt the aircraft upward. Conversely, the front motor speed decreases to ω-Δ pitch , the right motor speed increases to ω+Δ pitch, the flapping frequency of the front wings 1-4a and 1-4b will decrease synchronously, while the flapping frequency of the rear wings 1-4c and 1-4d will increase synchronously. At this time, the aerodynamic force and aerodynamic torque of the wings 1-4a and 1-4b decrease, while the aerodynamic force and aerodynamic torque of the wings 1-4c and 1-4d increase. The right rolling moment generated by wing 1-4a and the left rolling moment generated by wing 1-4b decrease synchronously and offset each other, the left rolling moment generated by wing 1-4c and the right rolling moment generated by wing 1-4d increase synchronously and offset each other, and the aircraft has no torque on the roll axis; the right yaw moment generated by wing 1-4a and the left yaw moment generated by wing 1-4b decrease synchronously and offset each other, the right yaw moment generated by wing 1-4c and the left yaw moment generated by wing 1-4d increase synchronously and offset each other, and the aircraft has no torque on the yaw axis; the nose-up moment generated by wings 1-4a and 1-4b decreases, and the nose-down moment generated by wings 1-4c and 1-4d increases, and the aircraft generates a downward nose-down moment on the pitch axis, which will cause it to lower its head.

[0097] S3, Yaw

[0098] like Figure 6c As shown, the speed of motors 1-1a and 1-1c is increased by Δ relative to the average speed ω. yaw , and simultaneously reduce the speed of motors 1-1b and 1-1d to ω-Δ yaw , the flapping frequencies of wings 1-4a and 1-4c will increase synchronously, while the flapping frequencies of wings 1-4b and 1-4d will decrease synchronously. At this time, the aerodynamic forces and aerodynamic moments of wings 1-4a and 1-4c increase, while the aerodynamic forces and aerodynamic moments of wings 1-4b and 1-4d decrease. The pitch moment generated by wing 1-4a and the nose-down moment generated by wing 1-4c increase synchronously and cancel each other out, while the pitch moment generated by wing 1-4b and the nose-down moment generated by wing 1-4d decrease synchronously and cancel each other out, resulting in no torque acting on the aircraft's pitch axis; the right roll moment generated by wing 1-4a and the left roll moment generated by wing 1-4c increase synchronously and cancel each other out, while the left roll moment generated by wing 1-4b and the right roll moment generated by wing 1-4c decrease synchronously and cancel each other out, resulting in no torque acting on the aircraft's roll axis; the right yaw moment generated by wings 1-4a and 1-4c increases, while the left yaw moment generated by wings 1-4b and 1-4d decreases, resulting in a right yaw moment on the aircraft's yaw axis, causing it to yaw to the right. Conversely, the speed of motors 1-1a and 1-1c is reduced to ω-Δ relative to the average speed. yaw , and simultaneously increase the speed of motors 1-1b and 1-1d to ω+Δ yaw, the flapping frequencies of wings 1-4a and 1-4c will decrease synchronously, while the flapping frequencies of wings 1-4b and 1-4d will increase synchronously. At this time, the aerodynamic forces and aerodynamic moments of wings 1-4a and 1-4c decrease, while the aerodynamic forces and aerodynamic moments of wings 1-4b and 1-4d increase. The nose-up moment generated by wing 1-4a and the nose-down moment generated by wing 1-4c decrease synchronously and cancel each other out, the nose-up moment generated by wing 1-4b and the nose-down moment generated by wing 1-4d increase synchronously and cancel each other out, and the aircraft has no torque on the pitch axis; the right roll moment generated by wing 1-4a and the left roll moment generated by wing 1-4c decrease synchronously and cancel each other out, the left roll moment generated by wing 1-4b and the right roll moment generated by wing 1-4c increase synchronously and cancel each other out, and the aircraft has no torque on the roll axis; the right yaw moment generated by wings 1-4a and wing 1-4c decreases, and the left yaw moment generated by wings 1-4b and wing 1-4d increases, and the aircraft generates a left yaw moment on the yaw axis, which will yaw to the left.

[0099] S4, lifting

[0100] like Figure 6d As shown, by increasing the speeds of the four motors 1-1a, 1-1b, 1-1c, and 1-1d simultaneously, the flapping frequency of wings 1-4a, 1-4b, 1-4c, and 1-4d increases. Once the generated lift exceeds the sum of drag and gravity, the aircraft will fly upward. Conversely, by decreasing the speeds of the four motors 1-1a, 1-1b, 1-1c, and 1-1d simultaneously, the flapping frequency of wings 1-1a, 1-4b, 1-1c, and 1-4d decreases. When the overall lift is less than gravity, the aircraft will descend. As the aircraft ascends or descends, the roll, pitch, and yaw moments cancel each other out.

[0101] In summary, for the four directly controlled degrees of freedom of a bionic quad-wing aircraft—roll, pitch, yaw, and lift—the effects of wing aerodynamic forces can be combined in aerodynamic control torque coupling to achieve a superposition and enhancement of the desired target torques while symmetrically canceling out the unwanted torques. These four attitude transformations can be achieved solely through frequency modulation. Furthermore, the aircraft's attitude transformations can be achieved simply by controlling the motor speed and adjusting the wing flapping frequency, without the need for additional control servos or adjustment mechanisms.

[0102] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A bionic mechanical dragonfly aircraft based on flapping frequency modulation, characterized in that: The aircraft comprises a frame, four wings symmetrically distributed on both sides of the frame, and four wing drive mechanisms arranged in one-to-one correspondence with the four wings; The wing drive mechanism includes a motor, a belt transmission mechanism and a swing guide rod mechanism; The belt transmission mechanism includes a first pulley and a second pulley that are coupled together by a transmission belt; the first pulley is connected to the motor; and a crank is provided on the second pulley; The swing guide rod mechanism includes a guide rod connected to the wing; the guide rod is provided with a guide rail corresponding to the rocker; Driven by the motor, the first pulley rotates, driving the second pulley to rotate through the transmission belt. Through the cooperation of the crank handle and the guide rail, the rotation of the second pulley is converted into the swing of the guide rod, thereby driving the movement of the wing connected to the guide rod.

2. The aircraft according to claim 1, characterized in that The frame includes a first support portion, a second support portion, and a third support portion connected between the first support portion and the middle section of the second support portion; The first supporting portion and the second supporting portion are both provided with a first pulley mounting shaft hole, a second pulley mounting shaft hole and a guide rod mounting shaft hole; Four motor mounting components are provided on the third supporting portion.

3. The aircraft according to claim 1 or 2, characterized in that The second pulley is mounted on the frame via a first rotating shaft; The guide rod is mounted on the frame via a second rotating shaft.

4. The aircraft according to claim 1, characterized in that The wings are mounted on the guide rods via connecting shafts; The wing is provided with a first connecting shaft hole; The guide rod is provided with a second connecting shaft hole and a wing connecting hole; The connecting shaft passes through the first connecting shaft hole and the second connecting shaft hole and is interference fit with the two connecting shaft holes; The guide rod is connected to the wing through the wing connecting hole and the connecting shaft.

5. The aircraft according to claim 2, characterized in that The first pulley includes a first pulley body, a first pulley groove arranged on the outer periphery of the middle section of the first pulley body, and a first mounting shaft hole opened in the middle of the first pulley body; The first pulley cooperates with the transmission belt through the first pulley groove, the second pulley cooperates with the transmission belt through the second pulley groove, and transmits rotation; The output shaft of the motor is interference-fitted with the first mounting shaft hole and has a clearance fit with the first pulley mounting shaft hole.

6. The aircraft according to claim 3, characterized in that The second pulley includes a second pulley body, a second pulley groove arranged on the outer periphery of the middle section of the second pulley body, and a second mounting shaft hole arranged in the middle of the second pulley body; The crank handle is arranged on the end surface of the second pulley body; The second pulley is mounted on the frame through the second mounting shaft hole, the first mounting shaft hole and the first rotating shaft are clearance-fitted, and the first rotating shaft and the second pulley mounting shaft hole are interference-fitted; The second pulley acts as a crank in the swing guide rod mechanism, and the rocker on it rotates a full circle. While rotating, the rocker moves relative to the guide rail of the guide rod, causing the guide rod to swing.

7. The aircraft according to claim 3, characterized in that The guide rod comprises a guide rod body and a third mounting shaft hole provided on the guide rod body; The guide rail is arranged on the guide rod body; The third mounting shaft hole on the guide rod is clearance-fitted with the second rotating shaft, and the second rotating shaft is mounted on the frame through interference fit with the mounting shaft hole of the guide rod.

8. The aircraft according to claim 1, characterized in that The wing comprises a wing frame surrounded by a leading edge and a trailing edge and a wing membrane installed in the middle of the wing frame; The wing frame is provided with a third connecting shaft hole.

9. The method for controlling an aircraft according to any one of claims 1 to 8, characterized in that: The method includes: S1, Roll The wings and motors are divided into left and right sides. The motor frequency on one side is increased while the frequency of the motor on the other side is simultaneously decreased. The attitude torque of the two wings on the side with increased motor frequency increases, while the attitude torque of the two wings on the side with decreased motor frequency decreases. The pitching moment and yaw moment generated by the four wings cancel each other out. At the same time, the generated rolling moments are superimposed on the center of mass to produce a clockwise rolling moment, causing the aircraft to roll toward the side with decreased motor frequency. S2, pitch The wings and motors are divided into the front and rear sides. The motor frequency on one side is increased and the motor frequency on the other side is simultaneously decreased. The attitude torque of the two wings on the side with the increased motor frequency increases, while the attitude torque of the two wings on the side with the decreased motor frequency decreases. The rolling torque and yaw torque generated by the four wings cancel each other out. At the same time, the pitching torque generated is superimposed on the center of mass to produce a counterclockwise pitching torque, causing the aircraft to pitch. S3, Yaw By increasing the frequency of the two motors on one diagonal of the frame and synchronously decreasing the frequency of the two motors on the other diagonal, the attitude torque of the wing corresponding to the motor with the increased frequency increases, while the attitude torque of the wing corresponding to the motor with the decreased frequency decreases. The rolling moment and pitching moment generated by the four wings cancel each other out. At the same time, the generated yaw moments are superimposed on the center of mass to produce a clockwise yaw moment, causing the aircraft to yaw. S4, lifting By adjusting the frequency of the four motors, the lift generated by the four wings changes, and the aircraft takes off and up actions.

10. The method according to claim 9, characterized in that The method further includes: By adjusting the motor frequency, the left forewing generates a counterclockwise rolling moment, a clockwise pitching moment, and a clockwise yaw moment; the right forewing generates a clockwise rolling moment, a clockwise pitching moment, and a counterclockwise yaw moment; the right hindwing generates a clockwise rolling moment, a counterclockwise pitching moment, and a clockwise yaw moment; and the left hindwing generates a counterclockwise rolling moment, a counterclockwise pitching moment, and a counterclockwise yaw moment.

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