A quasi-zero stiffness six-degree-of-freedom vibration reduction device for a drone gimbal

Abstract

The application relates to a quasi-zero stiffness six-degree-of-freedom damping device for a UAV holder, which comprises a supporting device and a damping device, the supporting device comprises a connecting seat, a load seat and a mounting seat, an external load equipment is mounted on the mounting seat, a three-axis rotating mechanism is arranged between the load seat and the mounting seat, the damping device comprises an upper damping unit and a lower damping unit, the upper damping unit and the lower damping unit are both composed of an upper end face, a lower end face and an elastic bending rod arranged between the upper end face and the lower end face, and the cross section of the elastic bending rod is a crescent cross section. Through the above improvement, the quasi-zero stiffness six-degree-of-freedom damping device can quickly and adaptively damp external vibration when the UAV is disturbed by vibration, has good damping effect in the movement and rotation along the x, y and z three orthogonal coordinate axes, can keep the stability of the external load equipment, reduces the influence of external vibration on the UAV, and thus improves the working performance and flight stability of the UAV.

Description

Technical Field

[0001] This invention relates to the field of drone vibration reduction gimbal technology, specifically to a quasi-zero stiffness six-degree-of-freedom vibration reduction device for drone gimbals. Background Technology

[0002] With the development of drone technology, the application scope of drones is constantly expanding, especially in fields such as aerial photography and monitoring, where significant progress has been made. However, during flight, drones are inevitably subject to complex interference from different frequency bands, such as external airflow, motor noise, and drone flight inertia, causing body vibration and preventing cameras from clearly capturing video and images. Therefore, efficient and reliable vibration-damping gimbals are needed to ensure that cameras, sensors, and other equipment can operate stably in complex flight environments.

[0003] A vibration damping gimbal is a key device used to reduce the vibration effects of external disturbances such as airflow, wind, and body vibration during the flight of a drone. The application of a vibration damping gimbal can maintain stable flight of the drone in complex vibration environments, while protecting the drone's onboard cameras, sensors, and other equipment from vibration interference, thereby improving the quality of camera shooting or monitoring, and ensuring the normal operation of sensors and other equipment.

[0004] Traditional vibration damping gimbal technology has several limitations. While it can reduce vibration transmission to some extent, its damping performance is poor due to the fixed linear stiffness design of the damping structure. Furthermore, it cannot adaptively adjust to the frequency and amplitude of external disturbances. This limits its effectiveness in complex and variable environments. Additionally, the fixed stiffness parameters of the linear gimbal's damping device restrict its frequency range, making it unsuitable for high-frequency or large-amplitude disturbances. When encountering external vibrations exceeding the design limits, traditional linear vibration damping gimbals may struggle to effectively reduce vibration transmission, potentially damaging onboard equipment or affecting the stability of the drone.

[0005] Therefore, it is essential to design a nonlinear stiffness gimbal vibration reduction device with good vibration reduction performance and adaptability to complex vibration interference environments to address the problems listed above. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the prior art and provide a quasi-zero stiffness six-degree-of-freedom vibration reduction device for UAV gimbals. The quasi-zero stiffness six-degree-of-freedom vibration reduction device has a good vibration reduction effect, can maintain the stability of external equipment mounted on the UAV, reduce the impact of external vibration on the UAV system, and thus improve the working performance and flight stability of the UAV.

[0007] The technical solution of this invention to solve the problems of the prior art is: A quasi-zero stiffness six-degree-of-freedom vibration damping device for a drone gimbal includes a support device and a plurality of vibration damping devices disposed within the support device, wherein... The support device includes a connecting seat, a load seat, and a mounting seat; wherein, the external load device is mounted on the mounting seat; the connecting seat is located above the load seat, and the load seat is located above the mounting seat, and a three-axis rotation mechanism is provided between the load seat and the mounting seat to cause the mounting seat to rotate around the X-axis, Y-axis, and Z-axis; The vibration damping device includes an upper vibration damping unit and a lower vibration damping unit; both the upper vibration damping unit and the lower vibration damping unit are composed of an upper end plate, a lower end plate, and an elastic bending rod disposed between the upper end plate and the lower end plate; the upper end plate and the lower end plate are coaxially arranged; wherein, the cross-section of the elastic bending rod is a crescent-shaped cross-section; The guide line of the elastic bending rod of the upper vibration damping unit in the length direction is a two-dimensional curve, represented by a hyperbolic function; the axis of symmetry of this guide line coincides with the mid-plane between the upper and lower end plates of the upper vibration damping unit; the guide line of the elastic bending rod of the lower vibration damping unit in the length direction is a two-dimensional curve, represented by a trigonometric function, and the axis of symmetry of this guide line coincides with the mid-plane between the upper and lower end plates of the lower vibration damping unit; the large circle and small circle in the cross-section of the elastic bending rod of the upper and lower vibration damping units intersect to form an inner arc and an outer arc, wherein the two endpoints of the inner arc and the outer arc are connected and have the same concave direction, thereby forming the crescent-shaped cross-section; Both the connecting seat and the load seat are provided with multiple connecting arms extending outward from their geometric center, and the multiple connecting arms are distributed in a circular pattern. The connecting seat includes an upper support plate and a lower support plate. The upper support plate has multiple extensions extending outward from its geometric center, which constitute the connecting arm of the connecting seat. The connecting arm of the connecting seat bends downward into a U-shape at its end to form the lower support plate. The lower end plate of the upper vibration damping unit is bolted to the upper end of the connecting arm of the load seat, and the upper end plate of the upper vibration damping unit is bolted to the connecting arm of the connecting seat. The upper end plate of the lower vibration damping unit is bolted to the lower end of the connecting arm of the load seat, and the lower end plate of the lower vibration damping unit is bolted to the lower support plate.

[0008] Preferably, the upper end of the connector is provided with a bracket, which is connected to the bottom of the drone fuselage.

[0009] Preferably, both the support device and the vibration damping device are made of lightweight, high-strength carbon fiber composite material.

[0010] Preferably, the vibration damping device is integrally molded using 3D printing technology, wherein the 3D printing material is thermoplastic polyurethane elastomer.

[0011] Compared with the prior art, the present invention has the following advantages: 1. The quasi-zero stiffness six-degree-of-freedom vibration damping device for UAV gimbals of the present invention has near-zero stiffness within its working range due to the series design of the special quasi-zero stiffness vibration damping units. When the UAV is subjected to external vibration interference during operation, the stiffness of the UAV gimbal is extremely low, and it can hardly exert any resistance to external vibration. When facing external interference of different frequencies and amplitudes, the quasi-zero stiffness six-degree-of-freedom vibration damping device of the present invention can provide a better vibration damping effect, maintaining the stability of the UAV and the stable operation of the onboard equipment.

[0012] 2. The quasi-zero stiffness six-degree-of-freedom vibration reduction device for UAV gimbals of the present invention has an adaptive vibration reduction effect; by adopting the quasi-zero stiffness six-degree-of-freedom vibration reduction device of the present invention, the UAV vibration reduction gimbal can adaptively adjust according to the frequency and amplitude of external interference, making the vibration reduction effect more flexible and efficient.

[0013] 3. The design of the quasi-zero stiffness six-degree-of-freedom vibration reduction device for UAV gimbals of the present invention can expand its vibration reduction range. Compared with the fixed stiffness of traditional linear vibration reduction gimbals, the introduction of quasi-zero stiffness in the present invention enables the vibration reduction gimbal to better adapt to external vibration interference beyond the design range, providing stronger stability assurance for UAVs in complex environments.

[0014] 4. The stiffness of the quasi-zero stiffness six-degree-of-freedom vibration damping device of the present invention is determined by the deformation of the upper and lower vibration damping units. Therefore, by adjusting the curvature, thickness and width of the elastic bending rod in the vibration damping unit, the overall stiffness of the upper and lower vibration damping units and the gimbal can be parametrically designed.

[0015] 5. Active vibration damping gimbals typically consume a significant amount of energy to maintain their damping effect, as they require actively adjusting stiffness and damping parameters to counteract external vibrations. The passive gimbal six-degree-of-freedom vibration damping device proposed in this invention can adaptively adjust its damping characteristics without requiring external energy input, thereby saving energy and extending the drone's endurance.

[0016] 6. The quasi-zero stiffness six-degree-of-freedom vibration reduction device of this invention adopts a passive vibration reduction method, which reduces the need for control algorithms and sensors compared to the complex control system of traditional linear vibration reduction gimbals. This simplifies the design of the UAV gimbal and reduces system maintenance costs and risks. Attached Figure Description

[0017] Figure 1This is a perspective view of the UAV gimbal equipped with a quasi-zero stiffness six-degree-of-freedom vibration reduction device according to the present invention.

[0018] Figure 2 This is a perspective view of the quasi-zero stiffness six-degree-of-freedom vibration reduction device of the present invention.

[0019] Figure 3 This is a perspective view of the vibration damping unit of the present invention.

[0020] Figure 4 This is a front view of the vibration damping unit of the present invention.

[0021] Figure 5 This is a cross-sectional view of the elastic bending rod of the vibration damping unit of the present invention.

[0022] Figure 6 This is a diagram showing the cross-sectional deformation of the elastic bending rod at different positions during the compression process of the vibration damping unit of the present invention.

[0023] Figure 7 This is a force-displacement curve of the quasi-zero stiffness six-degree-of-freedom vibration reduction device of the present invention.

[0024] Among them, 1-Vibration damping device; 2-Connecting seat; 3-Load seat; 4-Hanger; 5-Three-axis rotation mechanism; 6-External load equipment; 7-Upper support plate; 8-Lower support plate; 9-Upper end plate; 10-Lower end plate; 11-Elastic bending rod; 12-Upper vibration damping unit; 13-Lower vibration damping unit; 14-Inner arc; 15-Outer arc. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0026] See Figures 1-4 The quasi-zero stiffness six-degree-of-freedom vibration damping device for UAV gimbals of the present invention includes a support device and a plurality of vibration damping devices 1 disposed in the support device.

[0027] See Figures 1-4 The support device includes a connecting seat 2, a load seat 3, and a mounting seat; wherein an external device 6 (e.g., a camera) is mounted on the mounting seat; the connecting seat 2 is located above the load seat 3, and the load seat 3 is located above the mounting seat, and a three-axis rotation mechanism 5 is provided between the load seat 3 and the mounting seat to cause the mounting seat to rotate around the X-axis, Y-axis, and Z-axis.

[0028] See Figures 1-4The vibration damping device 1 includes an upper vibration damping unit 12 and a lower vibration damping unit 13; both the upper vibration damping unit 12 and the lower vibration damping unit 13 are composed of an upper end plate 9, a lower end plate 10, and an elastic bent rod 11 disposed between the upper end plate 9 and the lower end plate 10; the upper end plate 9 and the lower end plate 10 are circular and coaxially arranged, and are provided with bolt holes for connection and fixing, which can be connected to the connecting seat 2 and the load seat 3; wherein, the upper end plate 9 in the upper vibration damping unit 12 is connected to the connecting seat 2 and the load seat 3. The upper end of the seat 2 is connected, and the lower end plate 10 is connected to the upper end of the load seat 3; the upper end plate 9 of the lower damping unit 13 is connected to the lower end of the load seat 3, and the lower end plate 10 is connected to the lower end of the connecting seat 2; the cross-section of the elastic bending rod 11 is a crescent-shaped cross-section, and the large circle and small circle in the cross-section of the elastic bending rod 11 intersect to form an inner arc 14 and an outer arc 15; wherein, the two ends of the inner arc 14 and the outer arc 15 are connected and concave in the same direction, thus forming Figure 3 The crescent-shaped cross section. When the UAV gimbal (the quasi-zero stiffness six-degree-of-freedom vibration damping device of the present invention is connected to the three-axis rotation mechanism 5 to form the UAV gimbal) moves or rotates along the three rectangular coordinate axes x, y, and z, the upper end plate 9 and lower end plate 10 of the upper vibration damping unit 12 and the lower vibration damping unit 13 undergo relative displacement, causing the elastic bending rod 11 to compress and deform to generate quasi-zero stiffness.

[0029] See Figures 1-7 The principle by which the vibration damping device of the present invention generates nonlinear stiffness (taking vibration damping unit 13 as an example below): When the upper disk 9 of the current damping unit 13 is subjected to force, it transmits the external force to the elastic bending rod 11, causing the elastic bending rod 11 to compress and deform. To comprehensively analyze the relationship between the cross-sectional deformation and the nonlinear elastic force during the compression process, three specific locations (A, B, and C) of the elastic bending rod 11 were selected for evaluation; among them, Figure 6 The diagram shows the deformation process of the cross-section of the elastic rod 11 at different positions during axial compression of the lower damping unit 13; the stress is mainly distributed at the edges of the inner arc 14 and outer arc 15 of the cross-section. Comparing the shapes of the cross-section before and after compression reveals that the radii of curvature of both the inner and outer arcs 14 and 15 increase, and their shapes become increasingly flat, especially at position A. This deformation of the cross-sectional shape reduces the moment of inertia, thereby reducing the ability to resist bending moments. As the elastic rod 11 becomes increasingly flat under compression, the lower damping unit 13 is more easily compressed than before. This characteristic gives the elastic rod 11 nonlinear stiffness, resulting in high stiffness in the early stage of compression, allowing it to support heavy loads, while its stiffness at the static equilibrium point is very low, effectively reducing the natural frequency. Figure 7As shown in the force-displacement curve of the quasi-zero stiffness six-degree-of-freedom vibration damping device of the present invention, the elastic force gradually increases from the initial displacement, while the stiffness gradually decreases. As the displacement increases, the elastic force increases to a position where it is in equilibrium with the load weight. At this point, the stiffness gradually decreases to quasi-zero stiffness. Within the quasi-zero stiffness range, the lower damping unit 13 can withstand a large load mass while maintaining a very low resonance frequency, thus achieving excellent vibration damping effect over a wide frequency range. As the displacement continues to increase, the elastic force begins to rise sharply, and the stiffness gradually increases, resulting in a hardening effect. This effect can limit the large displacement of the UAV gimbal to prevent it from exceeding the safe displacement range of the UAV gimbal, ensuring the safe operation of the UAV gimbal and the external equipment 6.

[0030] See Figures 1-4 Both the connecting seat 2 and the load seat 4 are provided with three connecting arms extending outward from their geometric center, and the three connecting arms are distributed at equal angles around the circumference; the ends of the connecting arms are provided with grooves and bolt holes for connection and fixation to the upper end plate 9 or lower end plate 10 of the upper vibration damping unit 12 or the lower vibration damping unit 13.

[0031] See Figures 1-4 The connecting seat 2 includes an upper support plate 7 and a lower support plate 8. The lower end plate 10 of the upper vibration damping unit 12 is bolted to the upper end of the load seat 3, and the upper end plate 9 of the upper vibration damping unit 12 is bolted to the upper support plate 7. The upper end plate 9 of the lower vibration damping unit 13 is bolted to the lower end of the load seat 3, and the lower end plate 10 of the lower vibration damping unit 13 is bolted to the lower support plate 8. To facilitate the connection between the connecting seat 2 and the drone, a hanger 4 is provided at the upper end of the connecting seat 2. When the drone is subjected to external interference and vibrates, the vibration from the fuselage will be transmitted to the vibration damping device 1 through the hanger 4. The upper vibration damping unit 12 and the lower vibration damping unit 13 can absorb and consume vibration energy through deformation, reducing the vibration interference of the external equipment 6, thereby ensuring the normal operation of the external equipment 6.

[0032] In this embodiment, the connecting arm of the connecting seat 2 is bent downward into a U-shape at its end to form the lower support plate 8 of the connecting seat 2.

[0033] See Figures 1-4 The guide line of the elastic bending rod 11 of the upper vibration damping unit 12 in the length direction is a two-dimensional curve, represented by a hyperbolic function; the axis of symmetry of the guide line coincides with the mid-plane between the upper end plate 9 and the lower end plate 10 of the upper vibration damping unit 12.

[0034] See Figures 1-4The guide line of the elastic bending rod 11 of the lower damping unit 13 in the length direction is a two-dimensional curve, represented by a trigonometric function; the axis of symmetry of the guide line coincides with the mid-plane between the upper end plate 9 and the lower end plate 10 of the lower damping unit 13.

[0035] See Figures 1-4 The support device and vibration damping device 1 of the present invention are both made of lightweight and high-strength carbon fiber composite material; while the upper vibration damping unit 12, the lower vibration damping unit 13 and the elastic bending rod 11 are integrally formed by 3D printing technology, wherein the material of 3D printing is thermoplastic polyurethane elastomer.

[0036] See Figures 1-7 The specific working principle of the quasi-zero stiffness six-degree-of-freedom vibration reduction device of the present invention is as follows: In the absence of external vibration interference, the load seat 3 and the three-axis rotation mechanism 5 are suspended from the connecting seat 2 installed at the bottom of the UAV fuselage via the upper damping unit 12 and the lower damping unit 13.

[0037] When there is no gravity, the upper damping unit 12 and the lower damping unit 13 are in their initial undeformed state, and no elastic deformation force is generated. When gravity is considered, under the action of the gravity of the load seat 3 and the three-axis rotating mechanism 5, the load seat 3 and the three-axis rotating mechanism 5 are displaced vertically downward relative to the connecting seat 2. This displacement causes the elastic bending rod 11 between the upper end plate 9 and the lower end plate 10 of the lower damping unit 13 to be compressed. The elastic bending rod 11 undergoes compression deformation and generates a quasi-zero stiffness elastic force to support part of the gravity of the load seat 3 and the three-axis rotating mechanism 5. At the same time, within the working range of the gravity equilibrium position, the stiffness of the lower damping unit 13 is close to zero, which is beneficial for damping vibration. Under the gravity of the load base 3 and the three-axis rotating mechanism 5, the vertical downward displacement of the load base 3 and the three-axis rotating mechanism 5 relative to the connecting seat 2 will cause the upper end plate 9 and the lower end plate 10 of the upper vibration damping unit 12 to tend to move away axially, causing the elastic bending rod 11 to undergo elastic deformation. The tensile force of the elastic bending rod 11 resisting deformation offsets another part of the gravity of the load base 3 and the three-axis rotating mechanism 5. Therefore, under the supporting force and tensile force of the upper vibration damping unit 12 and the lower vibration damping unit 13, the UAV gimbal can maintain a stable state without vibration interference, and its stiffness is extremely low, close to zero.

[0038] When the drone gimbal is subjected to external vibration interference, the vibration damping device 1 moves in all six degrees of freedom, namely, it moves along the x, y, and z rectangular coordinate axes and rotates around the x, y, and z rectangular coordinate axes. Among these six degrees of freedom, the degrees of freedom of movement along the z-axis and rotation around the x and y axes can be converted into axial compression or tension of the vibration damping unit; the degrees of freedom of movement along the x and y axes and rotation around the z-axis can be converted into radial elastic deformation of the vibration damping unit.

[0039] When the UAV gimbal transitions from a static state to a disturbed state, the vibration damping device transitions from a stable state to a dynamically balanced state. At this point, the stiffness of the vibration damping device 1 remains close to zero in the directions of freedom of movement along the z-axis and rotation around the x and y axes. This means that within the quasi-zero stiffness operating range, the vibration damping device 1 exerts almost no resistance to the external vibration response transmitted by the load seat 3 and the three-axis rotation mechanism 5, exhibiting superior vibration damping performance compared to traditional linear stiffness vibration damping systems. Furthermore, the vibration damping device 1 can quickly and adaptively adjust its own stiffness within the quasi-zero stiffness operating range, thus effectively damping both low-frequency, large-amplitude and high-frequency, small-amplitude vibrations. For movement along the x and y axes and rotation around the z-axis, this can be converted into radial elastic deformation of the damping unit. Since the elastic bending rod 11 of the damping unit still has good elasticity in these directions, it also exhibits low stiffness and good vibration damping effect.

[0040] When the drone gimbal is subjected to external impact or significant vibration, the finite deformation and high stiffness of the elastic bending rod 11 under tension will limit the relative displacement between the connecting seat 2 and the load seat 3 to a safe range. This helps ensure the stability and safety of the externally mounted equipment 6 and avoids damage to the externally mounted equipment 6 due to excessive displacement. When the external vibration disappears, the upper damping unit 12 and the lower damping unit 13 will quickly return to their original state and release the previously stored elastic potential energy.

[0041] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A quasi-zero stiffness six-degree-of-freedom vibration damping device for UAV gimbals, characterized in that, It includes a support device and several vibration damping devices disposed in the support device, wherein, The support device includes a connecting seat, a load seat, and a mounting seat; wherein, the external load device is mounted on the mounting seat; the connecting seat is located above the load seat, and the load seat is located above the mounting seat, and a three-axis rotation mechanism is provided between the load seat and the mounting seat to cause the mounting seat to rotate around the X-axis, Y-axis, and Z-axis; The vibration damping device includes an upper vibration damping unit and a lower vibration damping unit; both the upper vibration damping unit and the lower vibration damping unit are composed of an upper end plate, a lower end plate, and an elastic bending rod disposed between the upper end plate and the lower end plate; the upper end plate and the lower end plate are coaxially arranged; wherein, the cross-section of the elastic bending rod is a crescent-shaped cross-section; The guide line of the elastic bending rod of the upper vibration damping unit in the length direction is a two-dimensional curve, represented by a hyperbolic function; the axis of symmetry of this guide line coincides with the mid-plane between the upper and lower end plates of the upper vibration damping unit; the guide line of the elastic bending rod of the lower vibration damping unit in the length direction is a two-dimensional curve, represented by a trigonometric function, and the axis of symmetry of this guide line coincides with the mid-plane between the upper and lower end plates of the lower vibration damping unit; the large circle and small circle in the cross-section of the elastic bending rod of the upper and lower vibration damping units intersect to form an inner arc and an outer arc, wherein the two endpoints of the inner arc and the outer arc are connected and have the same concave direction, thereby forming the crescent-shaped cross-section; Both the connecting seat and the load seat are provided with multiple connecting arms extending outward from their geometric center, and the multiple connecting arms are distributed in a circular pattern. The connecting seat includes an upper support plate and a lower support plate. The upper support plate has multiple extensions extending outward from its geometric center, which constitute the connecting arm of the connecting seat. The connecting arm of the connecting seat bends downward into a U-shape at its end to form the lower support plate. The lower end plate of the upper vibration damping unit is bolted to the upper end of the connecting arm of the load seat, and the upper end plate of the upper vibration damping unit is bolted to the connecting arm of the connecting seat. The upper end plate of the lower vibration damping unit is bolted to the lower end of the connecting arm of the load seat, and the lower end plate of the lower vibration damping unit is bolted to the lower support plate.

2. The quasi-zero stiffness six-degree-of-freedom vibration reduction device for UAV gimbals according to claim 1, characterized in that, The upper end of the connector is provided with a bracket, which is connected to the bottom of the drone fuselage.

3. The quasi-zero stiffness six-degree-of-freedom vibration reduction device for UAV gimbals according to claim 1, characterized in that, Both the support device and the vibration damping device are made of lightweight, high-strength carbon fiber composite material.

4. The quasi-zero stiffness six-degree-of-freedom vibration reduction device for UAV gimbals according to claim 1, characterized in that, The vibration damping device is manufactured in one piece using 3D printing technology, wherein the material used for 3D printing is thermoplastic polyurethane elastomer.

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