Flexible transmission mechanism for a micro ornithopter and method thereof

Abstract

The application discloses a flexible transmission mechanism of a micro flapping-wing aircraft and a method thereof, and belongs to the field of micro aircrafts. The mechanism comprises a crank chain, a flapping-wing chain, a constraint chain, a reduction gear set and a frame. The flapping-wing chain is composed of a moving platform and two groups of mirror-symmetrical rocker mechanisms, each group of the rocker mechanisms comprises a transmission connecting rod, a flapping rod and a fixed rod, the transmission connecting rod is hinged to the moving platform, the flapping rod is provided with a wing interface, and the moving platform reciprocatingly moves to drive the flapping rod to rotate around the hinge of the flapping rod and the fixed rod through the transmission connecting rod, so that the flapping-wing action is realized. The constraint chain comprises a fixed platform and two constraint branch chains, and forms a complete Sarrus mechanism with the moving platform, so that the moving platform is constrained to move only along a normal straight line of the platform. One end of the crank chain is connected to the moving platform, and the other end is connected to an external motor through the reduction gear set, so that continuous rotation is converted into reciprocating driving force. The mechanism has the remarkable advantages of lighter mass, smaller volume, greater structural rigidity and lower transmission loss.

Claims

1. A flexible transmission mechanism for a micro flapping-wing aircraft, characterized in that, It includes a crank chain (1), a flapping chain (2), a constraint chain (3), a reduction gear set (4), and a frame (5); The flapping wing chain (2) includes a moving platform (201) and two sets of rocker mechanisms; each set of rocker mechanisms is formed by a transmission link (202), a flapping rod (203) and a fixed rod (204) connected in sequence by hinges. The two sets of rocker mechanisms are connected to both sides of the moving platform (201) in a mirror symmetrical manner. The transmission link (202) is hinged to the moving platform (201), and the fixed rod (204) is fixedly assembled relative to the frame (5). The flapping rod (203) is provided with an interface for connecting the aircraft wing. During the reciprocating motion of the moving platform (201) along the normal direction of the platform plane, the transmission link (202) drives the flapping rod (203) to rotate back and forth about the hinge between the flapping rod (203) and the fixed rod (204) as the axis of rotation, thereby driving the wing to perform flapping action. The constraint chain (3) includes a fixed platform (301) and two constraint branches connected to both sides of the fixed platform (301). The fixed platform (301) is fixedly assembled on the frame (5) and connected to the moving platform (201) through the two constraint branches, thereby forming a complete Sarrus mechanism. The moving platform (201) is constrained to only make reciprocating linear motion along its platform plane normal. One end of the crank chain (1) is connected to the moving platform (201), and the other end is connected to the reduction gear set (4) driven by an external motor, thereby converting the continuous rotation input by the external motor into a reciprocating driving force for the moving platform (201) along the normal direction of the platform plane; Both the flapping wing chain (2) and the constraint chain (3) are assembled by folding after being integrally machined by SCM process. Their materials are composed of a middle flexible layer and two hard layers. When there is a hinge connection between the sub-components inside each component, the middle flexible layer needs to be continuous while the two hard layers are broken and form a toothed interlacing to form a rotating hinge.

2. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, In the flapping wing chain (2), the moving platform (201) and the flapping rod (203) are provided with connecting sections on both sides of the main body plane. After the connecting section is bent relative to the main body plane, it is fixed by the first insert piece (205) relative to the main body plane to form a U-shaped structure. The connecting sections on both sides of the moving platform (201) are respectively connected to the two transmission connecting rods (202) in a hinged manner. The connecting sections on both sides of each flapping rod (203) are respectively connected to the transmission connecting rod (202) and the fixed rod (204) in the rocker mechanism in a hinged manner.

3. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, In the constraint chain (3), the fixed platform (301) is engaged and assembled on the two fixed rods (204) on both sides of the flapping wing chain (2); each constraint branch includes two constraint links, and the two constraint links are indirectly connected by a pair of second plug-in pieces (304) to form a hinge-type connection. The axis of the hinge is parallel to the platform plane of the moving platform (201). Under the action of external force, the distance between the fixed end and the free end of the constraint link is adjusted by adjusting the opening angle. The free end of each constraint branch is provided with an interface for assembling and fixing the moving platform (201).

4. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, The crank chain (1) includes a crank connecting rod (101), a bearing sleeve (102), a bearing (103), a rudder shaft (104), and a rudder disc (105). One end of the crank connecting rod (101) is provided with a connecting section for assembling and fixing the moving platform (201) in the form of a hinge connection, and the other end is engaged with the bearing sleeve (102). The bearing sleeve (102) is equipped with the assembly of the bearing (103) and the rudder shaft (104). The rudder disc (105) has a shaft hole and a gear interface side by side. The bottom of the rudder shaft (104) is assembled in the shaft hole. The output gear of the reduction gear set (4) can be assembled into the gear interface to drive the rudder disc (105) to rotate, and then drive the moving platform (201) to reciprocate along the normal direction of the platform plane through the crank connecting rod (101).

5. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 4, characterized in that, The crank connecting rod (101) is integrally machined by SCM process, and there is a hinge connection between the connecting section of the crank connecting rod (101) used to assemble and fix the moving platform (201) and the main body. During processing, the middle flexible layer must be kept continuous while the hard layers on both sides are broken and form a toothed interlacing, thereby forming a rotating hinge.

6. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1 or 5, characterized in that, In the SCM process, the flexible layer is made of polyimide film, and the rigid layer is made of carbon fiber plate.

7. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, The reduction gear set (4) includes a multi-stage gear with cascaded meshing transmission, and each stage of gear adopts a double-layer cascaded gear; the reduction gear set (4) is assembled and fixed on the frame (5) by auxiliary parts.

8. The flexible transmission mechanism of the micro flapping-wing aircraft as described in claim 1, characterized in that, The frame (5) is assembled by plugging carbon fiber components, and has reserved assembly structures for the drive motor, as well as assembly slots for the flapping chain (2) and the reduction gear set (4).

9. A flapping wing control method for a flexible transmission mechanism of a micro flapping-wing aircraft as described in claim 1, characterized in that, The pair of wings of the aircraft are respectively mounted on the two flapping rods (203) of the flapping chain (2); then the external motor drives the reduction gear set (4), and under the drive of the end of the crank chain (1) and the constraint of the constraint chain (3), the moving platform (201) is driven to reciprocate linearly along the normal direction of its platform plane; during the reciprocating motion along the normal direction of the platform plane, the moving platform (201) drives the flapping rod (203) to reciprocate around the hinge between itself and the fixed rod (204) through the transmission link (202), thereby driving the wings mounted on the two flapping rods (203) to perform flapping actions.

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