A tail wing structure with independent pitching and rolling movement

Abstract

This invention relates to a tail fin structure with independent pitch and roll movements, comprising a pitch mechanism, a roll mechanism, and a connecting mechanism. The pitch mechanism includes a pitch servo and a pitch linkage, while the roll mechanism includes a roll servo and a transmission gear. The connecting mechanism includes a universal joint and a universal joint limiter. The pitch servo drives the tail fin to pitch movement via the pitch linkage. The roll servo drives the universal joint to rotate via the transmission gear, with the tail end of the universal joint connected to the tail fin to complete the roll movement. The rotation center of the pitch mechanism coincides with the center of the universal joint, and the left and right swing degrees of freedom of the universal joint are limited by the universal joint limiter, achieving independent control of pitch and roll movements. This invention allows for completely independent roll and pitch movements, significantly reducing the control precision requirements of the motor. The invention has a simple structure and reasonable design. The single-plane tail fin structure of this invention has strong wind resistance during flight and also has advantages such as low inertial load on the motor and high drive efficiency.

Description

Technical Field

[0001] This invention belongs to the field of flapping-wing aircraft measurement technology, specifically, it relates to a tail structure with independent pitch and roll motion. Background Technology

[0002] With their highly biomimetic characteristics, excellent flight efficiency, and outstanding maneuverability, flapping-wing aircraft have broad application prospects in reconnaissance, search and rescue, and other scenarios.

[0003] Birds in nature possess multi-degree-of-freedom wing and tail systems, with an intricate overall structure and coordinated movements. Limited by current manufacturing capabilities and material properties, artificially developed flapping-wing robots mostly employ simplified mechanical structures. The wings of these robots primarily provide the lift and thrust required for flight, while maneuvers such as turning typically rely on the tail fin.

[0004] The core function of the tail fin is to complete yaw and pitch movements. Currently, the mainstream designs are mainly divided into two categories: one is the dual-plane tail fin, which relies on the horizontal tail fin to control pitch and the vertical tail fin to achieve yaw. However, the vertical tail fin is easily affected by crosswinds, generating additional yaw force and has weak wind resistance. For example, the tail fin structure of a flapping-wing robot disclosed in Chinese patent CN120080989A has a vertical plane. If there is crosswind interference during stable flight, the vertical fin will cause a yaw moment, and this effect cannot be eliminated. The larger the vertical plane of the vertical fin, the more severe the interference and the weaker the wind resistance.

[0005] Another type is the single-plane tail fin, which achieves two attitude controls through a combination of roll and pitch movements. However, the roll mechanism of existing single-plane tail fins is difficult to assemble and is prone to coupling with pitch movements. Chinese patent CN120503955A discloses a novel bird-inspired tail fin multi-degree-of-freedom platform, in which the roll and pitch movements of the tail fin are controlled by a single servo motor. Pitch movement requires the bevel gears at the motor outputs to rotate in the same direction and maintain high synchronization to achieve pitch movement. If the motors on both sides rotate in opposite directions, the tail fin will roll. Roll movement also requires the bevel gears at the motor outputs to rotate in opposite directions and at the same speed. If they are not in opposite directions and at the same speed, the tail fin position will change during roll movement. Therefore, its tail fin control requires high-precision control of the output motors and high requirements for algorithms and control to achieve good pitch and roll effects. In this invention, the pitch and roll movements are performed independently, and the servo motors can be controlled independently, without the need for control algorithms to ensure control accuracy. Summary of the Invention

[0006] To overcome the technical problems existing in the prior art, the present invention provides a simple single-plane tail wing structure in which roll and pitch movements can be performed completely independently. Roll movement is achieved through a universal joint, and the left and right swing of the universal joint is limited by a limiting device. The single-plane structure reduces the impact of crosswinds and improves flight efficiency.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A tail fin structure with independent pitch and roll motion includes a tail fin. The tail fin structure includes a pitch mechanism, a roll mechanism, and a connecting mechanism. The pitch mechanism includes a pitch servo and a pitch linkage. The roll mechanism includes a roll servo and a transmission gear. The connecting mechanism includes a universal joint and a universal joint limiter. The pitch servo drives the tail fin to pitch motion through the pitch linkage. The roll servo drives the universal joint to rotate through the transmission gear. The tail end of the universal joint is connected to the tail fin to complete the roll motion. The rotation center of the pitch mechanism coincides with the center of the universal joint. The left and right swing degrees of freedom of the universal joint are limited by the universal joint limiter, realizing independent control of pitch and roll motion.

[0008] This invention achieves independent control directly through a mechanical structure (universal joint limiting and coincidence of rotation centers), without the need for algorithm decoupling. The universal joint limiting component restricts the universal joint to only swing up and down and rotate. By leveraging the universal joint's ability to effectively transmit power within its allowable angle range, independent control of both pitch and roll movements is achieved.

[0009] In this invention, pitch and roll movements are performed independently, and the servo motors can be controlled independently, eliminating the need for a control algorithm to ensure control accuracy.

[0010] Preferably, the tail fin structure further includes a fixing mechanism for fixing the pitch mechanism, roll mechanism and connecting mechanism. The fixing mechanism includes a fuselage fixing plate, fuselage and L-shaped connector.

[0011] Preferably, the rolling mechanism further includes a rolling servo mounting plate, a tail fin connector, a set screw fastener, a gear drive shaft, and a tail fin drive shaft; The pitch mechanism also includes a servo rocker arm, a pitch servo mounting plate, and a pitch connector; The connecting mechanism also includes a universal joint limiting plate and a universal joint limiting pin; The fuselage mounting plate, fuselage, pitch servo mounting plate and L-shaped connector are connected. The L-shaped connector is connected to the roll servo mounting plate and universal joint limit plate. The pitch servo is fixed on the pitch servo mounting plate. The output end of the pitch servo is connected to the servo rocker arm. The output end of the servo rocker arm is connected to the pitch linkage. One end of the pitch connector is connected to the pitch linkage. The other end is connected to the universal joint limit plate. The through hole at the center of the pitch connector is connected to the tail wing drive shaft at the output end of the universal joint.

[0012] In this invention, both the pitch and roll servos are fixedly connected to the fuselage, and all control servos are mounted on the fuselage. The output end of the servos consists only of a lightweight tail fin structure, reducing the output load of the servos and improving their control sensitivity. This invention simplifies the tail fin structure, reduces its mass, decreases the inertial load on the motor, and improves drive efficiency.

[0013] The universal joint of this invention has the characteristic of ensuring transmission under various deflection angles. The structure composed of limiting components can limit the left and right deflection of the universal joint when it encounters interference, and reduce the lateral force on the pitch link.

[0014] In the pitch mechanism, the rotation point of the pitch is the center point of the universal joint. The limit plate, limit pin, and limit component only ensure that the pitch mechanism always moves in the middle of the limit plate. The center of the universal joint mechanism remains unchanged during the movement, realizing the independence of the pitch motion from the yaw motion.

[0015] Preferably, the pitch linkage consists of a carbon fiber rod and a spherical bearing. During flight, if crosswind interference is encountered, due to the limited rigidity of the material, even if the limiting component deviates to some extent due to rigidity, the spherical bearing can still effectively transmit the force. The spherical bearing has a spherical hinge inside, so even if it deflects slightly, there is no problem.

[0016] Preferably, the universal joint limiting component is provided with a sliding groove, the sliding plane of the sliding groove is consistent with the plane of the pitch motion, and the universal joint limiting component achieves the limiting by sliding within the sliding groove through the universal joint limiting pin.

[0017] During pitching motion, the universal joint limit plate hinged to the upper end of the pitch connector pulls the limit pin to slide in the sliding groove. When encountering crosswinds, the left and right swaying of the pitch connector is restricted by the limit plate and the limit component, ensuring that the tail fin is within the normal range of motion.

[0018] Preferably, the output end of the roll servo is connected to a transmission gear, and two identical transmission gears mesh. The output transmission gear passes through the D-hole and through the gear drive shaft. The gear drive shaft is fitted with a bearing between itself and the roll servo mounting plate. One end of the gear drive shaft is restricted from axial movement by a set screw fastener, and the other end is connected to the hexagonal part of the universal joint for transmission. The output end of the universal joint is connected to the tail fin drive shaft and then passes through the pitch connector to restrict oscillation.

[0019] Preferably, the universal joint and the pitch connector are connected with a clearance, and the tail fin drive shaft is bolted to the tail fin. When the rolling servo rotates, it drives the drive shaft through gear transmission, causing the universal joint to roll, thereby causing the tail fin to roll.

[0020] Preferably, the pitch servo arm and the pitch connector are on the same plane. The pitch linkage may not be on the same plane. During pitch movement, the pitch servo controls the servo arm, transmitting force to the pitch connector via the pitch linkage, thus driving the pitch movement through the linkage mechanism. If the servo arm and the pitch connector are on opposite planes, and the pitch linkage is not parallel to the fuselage, the tail fin will experience force during flight when encountering rapids, which will be transmitted to the servo, resulting in a rollover moment and affecting the servo's lifespan.

[0021] This invention uses a servo motor to drive a servo arm, with a connecting rod at the end of the arm. The connecting rod drives the pitch connector to rotate around the center of the universal joint, similar to a parallel four-bar linkage. Since the universal joint's deflection is multi-degree-of-freedom, the pitch motion only occurs in the pitch plane. Furthermore, the two ends of the pitch connecting rod are joint bearings. Therefore, a limiting component is set to restrict the universal joint's deflection motion outside the pitch plane. By sliding the pin in the groove, the limiting component slides in the groove during the pitch motion without affecting the pitch motion. When encountering crosswinds and the tail fin is about to deflect and swing, the universal joint cannot swing in the horizontal plane because the limiting component clamps the pitch connector. The force generated by the crosswind is transmitted to the limiting component and then to the fuselage.

[0022] The output end of the roll servo is driven by a universal joint via a gear. The output end of the universal joint is connected to the tail fin drive shaft. The tail fin drive shaft and the hole of the pitch connector are installed with clearance. When transmission occurs, the tail fin drive shaft can rotate in the pitch connector, thereby driving the tail fin to roll.

[0023] The turning point of the pitch motion is the center point of the universal joint. The movement of the universal joint during the roll motion is independent of the turning point position. In this way, the pitch motion will not affect the roll motion, and the two movements are independent. Due to the presence of the limiting component, the universal joint can only deflect in the pitch motion direction and can transmit power at any position, ensuring the stability of the tail fin.

[0024] The beneficial effects of this invention are as follows: 1. In this invention, the roll motion and pitch motion can be performed completely independently, and the roll motion and pitch motion will not affect each other, which greatly reduces the control accuracy requirements of the motor. 2. The present invention has a simple structure and reasonable design. The single-plane tail fin structure of the present invention has strong resistance to wind disturbance during flight, and also has the advantages of low inertial load on motor and high drive efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the isometric structure of the present invention; Figure 2 This is a schematic diagram of the left side structure of the present invention; Figure 3 This is a top view schematic diagram of the structure driven by the present invention; Figure 4 This is a schematic diagram of the isometric side structure of the present invention from another angle; Figure 5 This is a schematic diagram of the structure of the present invention, which achieves left yaw by rolling 25 degrees to the left. Figure 6 This is a schematic diagram of the structure of the present invention, which achieves right yaw by rolling 25 degrees to the right; Figure 7 This is a schematic diagram of the structure of the present invention at an elevation angle of 30 degrees; Figure 8 This is a schematic diagram of the structure of the present invention at a 30-degree downward angle; Figure 9 This is a schematic diagram of the structure of the present invention with a left roll of 25 degrees and an elevation angle of 30 degrees; Illustration: 1. Fuselage mounting plate; 2. Fuselage; 3. L-shaped connector; 4. Roll servo mounting plate; 5. Universal joint limiter; 6. Tail fin connector; 7. Tail fin; 8. Universal joint limiter plate; 9. Universal joint limit pin; 10. Pitch linkage; 11. Pitch servo; 12. Servo rocker arm; 13. Pitch servo mounting plate; 14. Set screw fastener; 15. Gear drive shaft; 16. Roll servo; 17. Universal joint; 18. Tail fin drive shaft; 19. Pitch connector; 20. Drive gear. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and the technical solutions of the present invention will be further described in detail. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.

[0027] Reference Figure 1-4 A tail fin structure with independent pitch and roll motion includes a tail fin 7. The tail fin structure includes a pitch mechanism, a roll mechanism, and a connecting mechanism. The pitch mechanism includes a pitch servo 11 and a pitch linkage 10. The roll mechanism includes a roll servo 16 and a transmission gear 20. The connecting mechanism includes a universal joint 17 and a universal joint limiter 5. The pitch servo 11 drives the tail fin to pitch motion through the pitch linkage 10. The roll servo 16 drives the universal joint 17 to rotate through the transmission gear 20. The tail end of the universal joint 17 is connected to the tail fin 7 through the tail fin connector 6 to complete the roll motion. The rotation center of the pitch mechanism coincides with the center of the universal joint. The left and right swing degrees of freedom of the universal joint are limited by the universal joint limiter, realizing independent control of the pitch and roll motions.

[0028] The two movements of this invention are independent of each other and do not interfere with each other. They can be independently controlled by a servo motor, eliminating the need for complex algorithms to decouple the motor.

[0029] The universal joint model of this invention is 01G, and the limiting component is made of 6061 aluminum alloy, but it can also be made of 3D nylon printing, which can be determined according to the size of the tail fin.

[0030] The tail structure also includes a fixing mechanism for fixing the pitch mechanism, roll mechanism and connecting mechanism. The fixing mechanism includes a fuselage fixing plate 1, a fuselage 2 and a connecting piece 3.

[0031] The rolling mechanism also includes a rolling servo mounting plate 4, a tail fin connector 6, a set screw fastener 14, a gear drive shaft 15, and a tail fin drive shaft 18; the pitch mechanism also includes a servo rocker arm 12, a pitch servo mounting plate 13, and a pitch connector 19; the connecting mechanism also includes a universal joint limiting plate 8 and a universal joint limiting pin 9.

[0032] The fuselage mounting plate 1, fuselage 2, pitch servo mounting plate 13, and connector 3 are bolted together. Connector 3 is bolted together with roll servo mounting plate 4 and universal joint limit plate 8. Pitch servo 11 is fixed on pitch servo mounting plate 13. The output end of pitch servo 11 is connected to servo rocker arm 12. The output end of rocker arm is connected to pitch linkage 10. Pitch linkage 10 consists of a carbon fiber rod and a joint bearing. The joint bearing allows rocker arm 12 and pitch connector 19 to be in the vertical plane. There is a deviation, so the servo can still be effectively driven when the crosswind affects the pitch connector 19. One end of the pitch connector 19 is connected to the pitch linkage 10, and the other end is connected to the universal joint limiting plate 8. The through hole at the center of the pitch connector 19 is connected to the tail wing drive shaft at the output end of the universal joint. Since the mechanism composed of the universal joint limiting plate 8, the universal joint limiting pin 9 and the universal joint limiting member 5 restricts the swing of the pitch connector 19, the universal joint can only achieve pitch movement on the pitch motion plane and cannot deflect.

[0033] The output end of the roll servo is connected to gear 20, and the center of another gear is connected to the D hole of gear drive shaft 15. One end of the gear drive shaft is connected to universal joint 17, and the other end passes through the roll servo mounting plate 4. The shaft and the plate are connected by a bearing to reduce rolling resistance. The gear drive shaft 15 is fixed with screws after passing through the bearing to prevent the gear drive shaft from moving axially. The output end of universal joint 17 is connected to tail wing drive shaft 18, and the tail wing drive shaft is then bolted to the tail wing 7. When the roll servo rotates, it drives the drive shaft through the gear, causing the universal joint to roll, and finally causing the tail wing to roll.

[0034] The turning point of the pitch motion is the center point of the universal joint. The universal joint has the function of transmission in all directions. Therefore, when the pitch motion causes the universal joint to change, the roll motion can still be carried out. The degree of freedom of the universal joint is limited to left and right deflection by the limiting component. The universal joint can only achieve bending in the pitch direction, which improves the stability of the tail fin and realizes the independence of pitch and roll motion.

[0035] The state of the present invention at a leftward roll angle of 25 degrees is as follows Figure 5 As shown, the present invention is in a state with a right roll angle of 25 degrees as follows. Figure 6 As shown, the state of the present invention at an elevation angle of 30 degrees is as follows. Figure 7 As shown, the state of the present invention at a depression angle of 30 degrees is as follows. Figure 8 As shown, the state of the present invention at a left roll angle of 25 degrees and an elevation angle of 30 degrees is as follows. Figure 9 As shown. From Figures 5-9 As can be seen, when the roll angle is any position between 25 degrees left roll and 25 degrees right roll, the pitch motion is unrestricted and can move to any position between 30 degrees pitch angle and 30 degrees elevation angle. Similarly, when the pitch angle is any position between 30 degrees pitch angle and 30 degrees elevation angle, the roll motion is also unaffected. The present invention has the characteristic of achieving complete decoupling of roll motion and pitch motion.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tailplane structure for independent pitch and roll movement comprising a tailplane characterised in that: The tail fin structure includes a pitch mechanism, a roll mechanism, and a connecting mechanism. The pitch mechanism includes a pitch servo and a pitch linkage, and the roll mechanism includes a roll servo and a transmission gear. The connecting mechanism includes a universal joint and a universal joint limiter. The pitch servo drives the tail fin to pitch motion through the pitch linkage. The roll servo drives the universal joint to rotate through the transmission gear, and the tail end of the universal joint is connected to the tail fin to complete the roll motion. The rotation center of the pitch mechanism coincides with the center of the universal joint, and the left and right swing degrees of freedom of the universal joint are limited by the universal joint limiter, realizing independent control of the pitch and roll motions.

2. The tail fin structure with independent pitch and roll motion according to claim 1, characterized in that: The tail structure also includes a fixing mechanism for fixing the pitch mechanism, roll mechanism and connecting mechanism. The fixing mechanism includes a fuselage fixing plate, fuselage and L-shaped connector.

3. The tail fin structure with independent pitch and roll motion according to claim 1 or 2, characterized in that: The rolling mechanism also includes a rolling servo mounting plate, a tail fin connector, a set screw fastener, a gear drive shaft, and a tail fin drive shaft; The pitch mechanism also includes a servo rocker arm, a pitch servo mounting plate, and a pitch connector; The connecting mechanism also includes a universal joint limiting plate and a universal joint limiting pin; The fuselage mounting plate, fuselage, pitch servo mounting plate and L-shaped connector are connected. The L-shaped connector is connected to the roll servo mounting plate and the universal joint limit plate. The pitch servo is fixed on the pitch servo mounting plate. The output end of the pitch servo is connected to the servo rocker arm. The output end of the servo rocker arm is connected to the pitch linkage. One end of the pitch connector is connected to the pitch linkage. The other end is connected to the universal joint limit plate. The through hole at the center of the pitch connector is connected to the tail wing drive shaft at the output end of the universal joint.

4. The tail fin structure with independent pitch and roll motion according to claim 3, characterized in that: The pitch linkage consists of a carbon fiber rod and a spherical bearing.

5. The tail fin structure with independent pitch and roll motion according to claim 3, characterized in that: The universal joint limit component is provided with a sliding groove, and the universal joint limit component is limited by sliding within the sliding groove through the universal joint limit pin.

6. The tail fin structure with independent pitch and roll motion according to claim 3, characterized in that: The output end of the roll servo is connected to the transmission gear. Two identical transmission gears mesh, and the output transmission gear passes through the D hole and through the gear drive shaft. The gear drive shaft is fitted with a bearing between itself and the roll servo mounting plate. One end of the gear drive shaft is restricted from axial movement by a set screw fastener, and the other end is connected to the hexagon inside the universal joint for transmission. The output end of the universal joint is connected to the tail fin drive shaft and then passes through the pitch connector to restrict oscillation.

7. The tail fin structure with independent pitch and roll motion according to claim 6, characterized in that: The universal joint and the pitch connector are connected with a clearance, and the tail wing drive shaft is connected to the tail wing with bolts.

8. The tail fin structure with independent pitch and roll motion according to claim 3, characterized in that: The pitch servo rocker arm and the pitch connector are on the same plane.

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