Quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicle

Abstract

The invention discloses a quasi-zero stiffness sound array vibration isolation device for an unmanned aerial vehicle. The quasi-zero stiffness sound array vibration isolation device comprises a positive stiffness component and a negative stiffness component. The positive stiffness component is a steel spring, the upper end is connected with the unmanned aerial vehicle connecting piece, and the lower end is connected with the negative stiffness component; the negative stiffness component comprises a cylindrical permanent magnet and an annular permanent magnet, the cylindrical permanent magnet is located in an annular space of the annular permanent magnet after the acoustic array is mounted, and the cylindrical permanent magnet and the annular permanent magnet are in a mutual exclusion state; the steel spring, the cylindrical permanent magnet and the annular permanent magnet jointly form a quasi-zero-stiffness structure, and the quasi-zero-stiffness structure is located at a static balance position under the gravity effect of the sound array and stores elastic potential energy. When the unmanned aerial vehicle is disturbed by vibration transmitted by the unmanned aerial vehicle, the negative stiffness component releases elastic potential energy and generates acting force opposite to the disturbance direction so as to counteract vibration transmission. The device has the advantages of simple structure, suppression of vibration of the unmanned aerial vehicle and transmission of aerodynamic noise to a sound array, and the like.

Description

Technical Field

[0001] This invention mainly relates to the field of power equipment testing technology, specifically to a quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles (UAVs). Background Technology

[0002] With the large-scale development of power systems, acoustic inspection technology has become an important means of detecting discharge defects in transmission lines due to its non-contact, wide-coverage, and high-sensitivity characteristics. Using drones equipped with acoustic arrays enables all-weather acoustic monitoring of power facilities in complex terrains, allowing for timely detection of abnormal noises in transmission lines and other power facilities, significantly improving inspection efficiency and safety. However, one challenge this technology faces is that the drone rotor generates high-frequency vibrations and broadband aerodynamic noise, which, after being transmitted through the drone body to the acoustic array, creates strong background interference, causing a drop in the signal-to-noise ratio of discharge acoustic signals of over 40%, especially causing severe interference in overlapping frequency bands (such as 4-8kHz partial discharge ultrasound).

[0003] Vibration isolation structures can effectively suppress vibration interference generated by the UAV itself, but existing vibration isolation solutions have significant limitations: 1. Although passive rubber vibration isolators (such as silicone damping rings) can attenuate some high-frequency vibrations, their natural frequency is usually >20Hz, making it difficult to isolate low-frequency vibrations (<10Hz), and they are prone to resonance amplification. 2. Traditional spring-damping systems require sacrificing load-bearing capacity to achieve low-frequency vibration isolation, while acoustic array devices have a large mass for the drones they are mounted on, which can lead to insufficient stability of the acoustic array platform; 3. Electromagnetic active vibration isolation has high energy consumption and complex structure, making it unsuitable for unmanned aerial vehicle platforms with limited loads. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides a quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles that isolates the transmission path of interference signals.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles (UAVs) is provided. The device is connected between the UAV and the acoustic array to suppress the transmission of UAV vibration and aerodynamic noise to the acoustic array. The device includes a positive stiffness component and a negative stiffness component. The positive stiffness component is a steel spring, with its upper end connected to a UAV connector and its lower end connected to the negative stiffness component. The negative stiffness component includes a cylindrical permanent magnet and a ring permanent magnet. After the acoustic array is mounted, the cylindrical permanent magnet is located within the ring space of the ring permanent magnet, and the cylindrical permanent magnet and the ring permanent magnet are in a mutually repulsive state. The steel spring, cylindrical permanent magnet, and ring permanent magnet together form a quasi-zero stiffness structure, which is in static equilibrium under the gravity of the acoustic array and stores elastic potential energy. When subjected to vibration interference from the UAV, the negative stiffness component releases elastic potential energy and generates a force opposite to the direction of interference to counteract the vibration transmission.

[0006] Preferably, the vibration isolation device further includes a housing, the upper end of which is fixed to the top of the housing and connected to the drone via a drone connector.

[0007] Preferably, the vibration isolation device further includes a first acoustic array connector and a second acoustic array connector, one end of the first acoustic array connector is connected to the acoustic array, and the other end is connected to one end of the second acoustic array connector, and the other end of the second acoustic array connector is connected to a cylindrical permanent magnet.

[0008] Preferably, the other end of the first acoustic array connector is connected to one end of the second acoustic array connector via a ball joint structure.

[0009] Preferably, the ball head structure is provided with a locking screw.

[0010] The present invention also discloses an acoustic inspection system for unmanned aerial vehicles (UAVs), including a UAV and an acoustic array, and further including a quasi-zero stiffness acoustic array vibration isolation device for UAVs as described above.

[0011] This invention further discloses a method for suppressing acoustic array vibration based on the quasi-zero stiffness acoustic array vibration isolation device for UAVs as described above, comprising: Positive stiffness is provided by steel springs, and negative stiffness is provided by the mutual repulsion between cylindrical permanent magnets and ring permanent magnets, together forming a quasi-zero stiffness system; After the acoustic array is mounted, the system automatically reaches a static equilibrium state and stores elastic potential energy. When the drone vibrates, the negative stiffness component releases elastic potential energy, generating a reverse force to counteract the vibration energy and suppress the transmission of vibration to the acoustic array.

[0012] Compared with the prior art, the advantages of the present invention are as follows: This invention utilizes a quasi-zero stiffness structure (a combination of positive stiffness steel springs and negative stiffness magnets) to automatically achieve static equilibrium after the acoustic array is mounted. The negative stiffness magnetic ring (a combination of cylindrical and annular permanent magnets that repel each other) releases stored energy to generate a reverse force, effectively counteracting high-frequency vibrations (such as rotor flutter) and aerodynamic noise transmission from the UAV body. It also isolates interference signal transmission paths, significantly improving the signal-to-noise ratio of electrical discharge acoustic signals (such as those in the 4-8kHz frequency band), thus addressing the limitation of traditional structures in filtering wideband background noise. By suppressing vibration interference through the structure proposed in this invention, the phase distortion of the partial discharge ultrasonic signals acquired by the acoustic array is significantly reduced, avoiding overlap with the inspected characteristic frequency band. This directly minimizes the sound source localization error, ensuring sub-meter level accuracy in power line defect detection and improving the reliability and efficiency of UAV power line inspection.

[0013] This invention employs a passive design using steel springs and permanent magnet negative stiffness components, requiring no external power supply. It achieves near-zero stiffness through gravity-adaptive balancing; the structure is lightweight, easy to install, and can adjust vibration isolation performance in real time according to the acoustic array quality. Maintenance costs are low, making it suitable for various UAV inspection scenarios. Furthermore, this vibration isolation device 2 has a simple structure, is easy to manufacture, and is inexpensive, making it suitable for widespread adoption. Attached Figure Description

[0014] Figure 1 This is a structural diagram of the UAV acoustic inspection system of the present invention in an embodiment.

[0015] Figure 2 This is a three-dimensional structural diagram of the quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles according to an embodiment of the present invention.

[0016] Legend: 1. Drone; 2. Vibration isolation device; 2-1. Steel spring; 2-2. Ring permanent magnet; 2-3. Cylindrical permanent magnet; 2-4. Outer shell; 2-5. First acoustic array connector; 2-6. Locking screw; 2-7. Second acoustic array connector; 2-8. Drone connector; 3. Acoustic array. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] like Figures 1-2 As shown, the quasi-zero stiffness acoustic array vibration isolation device for UAVs provided in this embodiment of the invention is located between UAV 1 and acoustic array 3, and is used to suppress the transmission of vibration of UAV 1 and aerodynamic noise to acoustic array 3. The vibration isolation device 2 includes a positive stiffness component and a negative stiffness component; the positive stiffness component is a steel spring 2-1, the upper end of which is connected to the UAV connector 2-8, and the lower end is connected to the negative stiffness component; the negative stiffness component includes an annular permanent magnet 2-2 and a cylindrical permanent magnet 2-3. After the acoustic array 3 is mounted, the cylindrical permanent magnet 2-3 is located in the annular space of the annular permanent magnet 2-2, and the cylindrical permanent magnet 2-3 and the annular permanent magnet 2-2 are in a mutually repulsive state; The steel spring 2-1, the cylindrical permanent magnet 2-3, and the annular permanent magnet 2-2 together form a quasi-zero stiffness structure; among them, the steel spring 2-1, as a positive stiffness component, is a steel tension spring; the upper end of the steel spring 2-1 is connected to the UAV connector 2-8 and fixed to the top of the outer shell 2-4, and the lower end of the steel spring 2-1 is connected to the cylindrical permanent magnet 2-3, which mainly serves to support the acoustic array 3 installed at the bottom; The cylindrical permanent magnet 2-3 and the annular permanent magnet 2-2 are combined as a negative stiffness component; after the cylindrical permanent magnet 2-3 is mounted on the acoustic array 3, its position is located in the annular space of the annular permanent magnet 2-2, and the cylindrical permanent magnet 2-3 and the annular permanent magnet 2-2 are mutually repulsive in this state. The stiffness parameter of the steel spring 2-1 can be adjusted according to the mass of the acoustic array 3 it bears. After the lower acoustic array 3 is assembled, under the action of the gravity of the acoustic array 3 and the elastic tension of the positive stiffness component steel spring 2-1, the cylindrical permanent magnet 2-3 and the ring permanent magnet 2-2 form a negative stiffness structure in a static equilibrium position of a quasi-zero stiffness structure, storing a certain amount of elastic potential energy. When the UAV 1 is running, the vibration of the body itself and the aerodynamic noise will cause disturbance to the lower structure. At this time, the elastic potential energy stored in the negative stiffness structure formed by the cylindrical permanent magnet 2-3 and the ring permanent magnet 2-2 is released, generating a force opposite to the direction of the disturbance force of the UAV 1 body. This counteracts most of the energy required for the steel spring 2-1 to deform, and ultimately isolates the vibration of the UAV 1 body and the wind vibration from being transmitted to the acoustic array 3.

[0019] This invention utilizes a quasi-zero stiffness structure (a combination of positive stiffness from steel springs and negative stiffness from magnets) to automatically achieve static equilibrium after the acoustic array is mounted. The negative stiffness magnetic ring (a combination of cylindrical and annular permanent magnets that repel each other) releases stored energy to generate a reverse force, effectively counteracting high-frequency vibrations (such as rotor flutter) and aerodynamic noise transmission from the UAV body, isolating interference signal transmission paths, and significantly improving the signal-to-noise ratio of electrical discharge acoustic signals (such as the 4-8kHz frequency band), thus solving the problem that traditional structures cannot filter wideband background noise. After the structure proposed in this invention suppresses vibration interference, the phase distortion of the partial discharge ultrasonic signal acquired by the acoustic array is significantly reduced, avoiding the problem of overlap with the detected characteristic frequency band, directly minimizing the sound source positioning error, ensuring that the detection accuracy of power transmission line defects reaches the sub-meter level, and improving the reliability and efficiency of UAV power inspection.

[0020] This invention employs a passive design using steel springs and permanent magnet negative stiffness components, requiring no external power supply. It achieves near-zero stiffness through gravity-adaptive balancing; the structure is lightweight, easy to install, and can adjust vibration isolation performance in real time according to the acoustic array quality. Maintenance costs are low, making it suitable for various UAV inspection scenarios. Furthermore, this vibration isolation device 2 has a simple structure, is easy to manufacture, and is inexpensive, making it suitable for widespread adoption.

[0021] like Figure 1 As shown, this embodiment of the invention also provides an acoustic inspection system for unmanned aerial vehicles (UAVs), including a UAV 1, an acoustic array 3, and a quasi-zero stiffness acoustic array vibration isolation device for UAVs as described above.

[0022] This invention further provides a method for suppressing acoustic array vibration based on the quasi-zero stiffness acoustic array isolation device for unmanned aerial vehicles as described above, comprising: Positive stiffness is provided by steel spring 2-1, and negative stiffness is provided by the mutual repulsion between cylindrical permanent magnet 2-3 and ring permanent magnet 2-2, together forming a quasi-zero stiffness system; After the acoustic array 3 is mounted, the system automatically reaches a static equilibrium state and stores elastic potential energy. When the drone 1 vibrates, the negative stiffness component releases elastic potential energy, generates a reverse force, counteracts the vibration energy, and suppresses the transmission of vibration to the acoustic array 3.

[0023] This invention introduces a negative stiffness mechanism / structure to form an internal quasi-zero stiffness vibration isolation support system. This system not only supports the weight of the acoustic array 3 but also ensures extremely low dynamic stiffness near the static equilibrium position, creating an ideal passive vibration isolator. Through the aforementioned quasi-zero stiffness vibration isolation components, this invention effectively reduces the transmission of body noise and aerodynamic noise from the UAV to the acoustic array body via the structure. Ultimately, this reduces the interference of the UAV's own vibration noise on the acoustic array positioning test, improving the positioning accuracy and precision of the UAV-mounted acoustic array.

[0024] The vibration isolation structure of this invention can effectively isolate the high-frequency vibration of the UAV rotor and broadband aerodynamic noise from being transmitted to the acoustic array through the airframe structure. It can effectively suppress the interference of UAV body vibration and noise on the acoustic array, improve the positioning accuracy and precision of UAV acoustic inspection, and enhance the efficiency of acoustic inspection in power systems. Specifically, this invention can improve the efficiency of UAV-equipped acoustic array inspection, and its advantages are as follows: 1. Breakthrough in low-frequency vibration isolation: The system's natural frequency can be reduced to below 1Hz, improving vibration isolation efficiency by ≥90% in the 0.5-100Hz main vibration frequency band of UAVs; 2. High static and low dynamic characteristics: Static load capacity reaches 10kg (suitable for large acoustic arrays), and dynamic stiffness is reduced to 1 / 50 of that of traditional structures; 3. Enhanced anti-interference: Experiments show that this structure improves the signal-to-noise ratio of the acoustic array by 12dB and increases the accuracy of discharge defect identification to 98.7%.

[0025] Compared to spring-based negative stiffness solutions (which require pre-compression and are prone to instability) and single-magnetic-ring structures (which exhibit large nonlinear fluctuations in stiffness), the dual-magnetic-ring coupling design of this invention, through magnetic field gradient compensation, suppresses negative stiffness fluctuations to within ±5%, ensuring stable vibration isolation across a wide frequency range. This invention provides an efficient vibration suppression solution for UAV acoustic positioning and inspection.

[0026] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles (UAVs), characterized in that, The vibration isolation device (2) is connected between the UAV (1) and the acoustic array (3) to suppress the vibration of the UAV (1) and the transmission of aerodynamic noise to the acoustic array (3). The vibration isolation device (2) includes a positive stiffness component and a negative stiffness component. The positive stiffness component is a steel spring (2-1), the upper end of which is connected to the UAV connector (2-8), and the lower end is connected to the negative stiffness component. The negative stiffness component includes a cylindrical permanent magnet (2-3) and an annular permanent magnet (2-2). After the cylindrical permanent magnet (2-3) is mounted on the acoustic array (3), it is located in the annular space of the annular permanent magnet (2-2), and the cylindrical permanent magnet (2-3) and the annular permanent magnet (2-2) are in a mutually exclusive state. The steel spring (2-1), the cylindrical permanent magnet (2-3), and the ring permanent magnet (2-2) together constitute a quasi-zero stiffness structure. Under the gravity of the acoustic array (3), it is in a static equilibrium position and stores elastic potential energy. When it is disturbed by the vibration transmitted from the UAV (1), the negative stiffness component releases the elastic potential energy and generates a force opposite to the direction of the disturbance to counteract the vibration transmission.

2. The quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles according to claim 1, characterized in that, The vibration isolation device (2) also includes a housing (2-4), the upper end of the steel spring (2-1) is fixed to the top of the housing (2-4), and is connected to the drone (1) through the drone connector (2-8).

3. The quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles according to claim 1, characterized in that, The vibration isolation device (2) further includes a first acoustic array connector (2-5) and a second acoustic array connector (2-7). One end of the first acoustic array connector (2-5) is connected to the acoustic array (3), and the other end is connected to one end of the second acoustic array connector (2-7). The other end of the second acoustic array connector (2-7) is connected to the cylindrical permanent magnet (2-3).

4. The quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles according to claim 3, characterized in that, The other end of the first acoustic array connector (2-5) is connected to one end of the second acoustic array connector (2-7) through a ball joint structure.

5. The quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles according to claim 4, characterized in that, The ball head structure is equipped with locking screws (2-6).

6. An acoustic inspection system for unmanned aerial vehicles (UAVs), comprising a UAV (1) and an acoustic array (3), characterized in that, It also includes a quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles as described in any one of claims 1-5.

7. A method for suppressing acoustic array vibration based on the quasi-zero stiffness acoustic array vibration isolation device for unmanned aerial vehicles according to any one of claims 1-5, characterized in that, include: Positive stiffness is provided by a steel spring (2-1), and negative stiffness is provided by the mutual repulsion between the cylindrical permanent magnet (2-3) and the ring permanent magnet (2-2), together forming a quasi-zero stiffness system; After the acoustic array (3) is mounted, the system automatically reaches a static equilibrium state and stores elastic potential energy; When the UAV (1) vibrates, the negative stiffness component releases elastic potential energy, generates a reverse force, counteracts the vibration energy, and suppresses the transmission of vibration to the acoustic array (3).

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