A sound insulation device for acoustic arrays suitable for use on unmanned aerial vehicles and its design method

Abstract

This invention discloses a sound array sound insulation device and its design method suitable for use on unmanned aerial vehicles (UAVs). The sound array sound insulation device includes a soundproof enclosure, inside which is a sound sensor array. The sound sensor array includes a fixing plate, sound sensors, and array accessories. The array accessories include some or all of a power supply board and a signal transmission module. The fixing plate is fixed inside the soundproof enclosure and divides the enclosure into front and rear cavities. Multiple sound sensors are arranged in an array on the surface of the front cavity of the fixing plate, and the array accessories are mounted on the surface of the rear cavity of the fixing plate. This invention aims to address the noise characteristics of UAVs and the noise characteristics of typical discharge defects by providing a sound array sound insulation solution suitable for use on UAVs, thereby reducing the impact of UAV noise on measurements and improving the ability of UAVs to identify discharge defects in power transmission lines using a sound array.

Description

Technical Field

[0001] This invention belongs to the field of acoustic measurement technology, specifically relating to a sound insulation device for acoustic arrays suitable for use on unmanned aerial vehicles and its design method. Background Technology

[0002] Transmission lines are a crucial component of the power system and a key focus of power companies' daily operation and maintenance. Abnormal discharges are a common phenomenon caused by defects in transmission lines, such as insulator contamination, damage, and broken strands. Discharges are accompanied by simultaneous physical changes, including heat and sound. Therefore, infrared imaging, ultrasound, and acoustic array imaging technologies are commonly used for monitoring, primarily by human operators using handheld instruments. Drones, with their convenience and speed, are increasingly being used in substation and transmission line inspections. While drones equipped with infrared imaging and visible light optical devices are now commonplace, the use of drones with acoustic arrays for discharge point location is still in its early stages. This is mainly because drone rotor noise has high sound pressure levels and a wide frequency distribution, significantly hindering the acoustic array location of abnormal discharge points on transmission lines. Therefore, achieving sound insulation for drone-compatible acoustic arrays has become a critical technical challenge that urgently needs to be addressed. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a sound insulation device for an acoustic array that is suitable for use on drones and its design method, in view of the above-mentioned problems of the prior art. The present invention aims to provide a sound insulation solution for an acoustic array that is suitable for use on drones, based on the noise characteristics of drones and the noise characteristics of typical discharge defects, so as to reduce the impact of drone noise on measurement and improve the ability of drones to identify discharge defects in power transmission lines.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A sound insulation device for use on unmanned aerial vehicles (UAVs) includes a soundproof enclosure. An acoustic sensor array is housed inside the enclosure. The acoustic sensor array includes a mounting plate, acoustic sensors, and array accessories. The array accessories include some or all of a power supply board and a signal transmission module. The mounting plate is fixed inside the soundproof enclosure and divides the enclosure into front and rear cavities. Multiple acoustic sensors are arranged in an array on the surface of the front cavity of the mounting plate, and the array accessories are mounted on the surface of the rear cavity of the mounting plate.

[0006] Optionally, the soundproof enclosure is installed at an angle downwards in front of the drone with a vertical pitch angle of 45 degrees, the vertical pitch angle being the angle between the axis of the soundproof enclosure and the horizontal plane of the drone.

[0007] Optionally, the front opening edge of the soundproof enclosure is provided with a flared opening, the outer surface of which has an arc-shaped cross-section, and the center of the arc is located at the farthest point P of the UAV's rotor deployment, and satisfies the following constraints:

[0008] ,

[0009] in, Let P be the point on the farthest side of the rotor deployment and C be the endpoint of the bell opening. The line segment between point B, the lower edge of the front opening of the soundproof enclosure, and point C, the endpoint of the horn-shaped opening, is... Let P be the point on the farthest side of the rotor deployment, and B be the edge of the lower front opening of the soundproof enclosure. This is the wavelength corresponding to the lowest frequency in acoustic array imaging.

[0010] Optionally, the array arrangement refers to multiple acoustic sensors forming multiple concentric rings.

[0011] Optionally, a camera is arranged at the center of the annular shape on the fixing plate.

[0012] Optionally, the soundproof enclosure is made of rigid soundproof material.

[0013] Optionally, the inner wall of the soundproof enclosure is wrapped with a layer of sound-insulating material, the outer wall is wrapped with a layer of sound-absorbing material, and the rear cavity of the soundproof enclosure is filled with sound-absorbing material.

[0014] Optionally, the sound-absorbing material is a damping sound-insulating felt or polyester fiber sound-absorbing cotton.

[0015] The present invention also provides a rotary-wing unmanned aerial vehicle (UAV), including a UAV body, a suspension connecting rod provided on the lower side of the UAV body, and the aforementioned acoustic array sound insulation device suitable for UAV mounting is installed and fixed on the suspension connecting rod.

[0016] The present invention also provides a design method for the aforementioned acoustic array sound insulation device suitable for use on unmanned aerial vehicles, comprising the following steps:

[0017] S1, Determine the outer shell size of the soundproof enclosure based on the outer contour of the acoustic sensor array;

[0018] S2, Determine the depth of the rear cavity of the soundproof enclosure based on the size of the array accessories;

[0019] S3, determine the depth of the front cavity of the soundproof enclosure based on the camera's angle;

[0020] S4, determine the vertical pitch angle of the soundproof enclosure;

[0021] S5. Taking the furthest point P of the UAV's rotor as the center, and the outer edge of the front opening of the soundproof enclosure as the starting point A, draw an arc line with a specified central angle as the outer wall of the horn opening, satisfying the following constraints:

[0022] ,

[0023] in, Let P be the point on the farthest side of the rotor deployment and C be the endpoint of the bell opening. The line segment between point B, the lower edge of the front opening of the soundproof enclosure, and point C, the endpoint of the horn-shaped opening, is... Let P be the point on the farthest side of the rotor deployment, and B be the edge of the lower front opening of the soundproof enclosure. The wavelength corresponding to the lowest frequency of acoustic array imaging is determined, and the opening of the horn is connected to the inner edge of the front opening of the soundproof cover to form a complete cross-section of the horn, thereby determining the structure of the horn.

[0024] S6. Based on the height of the drone body above the ground and the size of the soundproof enclosure when the drone is parked, determine the installation position of the soundproof enclosure and the suspension connecting rod so that the distance d between the lower part of the soundproof enclosure and the ground when the drone is parked is not less than the preset safety distance.

[0025] S7, Determine the rigid sound insulation material of the soundproof enclosure;

[0026] S8, determine the material and thickness of the sound insulation material layer wrapped on the inner wall of the soundproof enclosure and the sound absorption material layer wrapped on the outer wall, and determine the material and thickness of the sound absorption material filling the rear cavity of the soundproof enclosure.

[0027] S9. Determine whether the overall quality of the sound array sound insulation device meets the rated load index of the drone. If the overall quality of the sound array sound insulation device does not meet the rated load index of the drone, then jump to step S1 to adjust the design of the sound array sound insulation device. Otherwise, determine that the design of the sound array sound insulation device is complete, end and exit.

[0028] Compared with existing technologies, the present invention has the following main advantages: Based on the differences and characteristics of the noise spectrum of discharge defects and the noise spectrum of UAVs, and utilizing the principle of sound insulation, the present invention designs a sound insulation structure. The noise spectrum of UAVs is mainly low to medium frequency, while the noise of discharge defects is mainly high to medium frequency. Therefore, the imaging (localization) of the discharge sound array of transmission lines should utilize high-frequency sound wave signals. Taking advantage of the strong directivity of high-frequency sound, the sound insulation structure is designed with reasonable size relationships. This reduces the noise of UAVs acquired by the sound array's sound sensors without affecting the reception of the noise from the discharge point sound source, thereby improving the signal-to-noise ratio of the discharge sound signal acquired by the sound array and enabling the localization of discharge sound sources at greater distances or with lower intensity. Therefore, the present invention addresses the noise characteristics of UAVs and the noise characteristics of typical discharge defects, providing a sound insulation scheme suitable for UAV-mounted sound arrays. This reduces the impact of UAV noise on measurements and enhances the ability of UAV-mounted sound arrays to identify discharge defects in transmission lines. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the installation structure of the sound array sound insulation device in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the acoustic sensor array in an embodiment of the present invention.

[0031] Figure 3 This is a side view of the soundproof enclosure in an embodiment of the present invention.

[0032] Figure 4 This is a cross-sectional view of the soundproof enclosure in an embodiment of the present invention.

[0033] Figure 5 The sound pressure level is located 1m directly below the drone (DJI M300) at different altitudes in this embodiment of the invention.

[0034] Figure 6 This is a schematic diagram illustrating the design process of the acoustic array sound insulation device in an embodiment of the present invention.

[0035] Legend: 1. Soundproof enclosure; 11. Horn; 2. Sound sensor array; 21. Fixing plate; 22. Sound sensor; 23. Array accessories; 24. Camera; 3. UAV body; 4. Suspension connecting rod. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment provides a sound array sound insulation device suitable for use on drones, including a sound insulation cover 1. The sound insulation cover 1 is provided with a sound sensor array 2 inside. The sound sensor array 2 includes a fixing plate 21, sound sensors 22, and array accessories 23. The array accessories 23 include part or all of the power board and signal transmission module. The fixing plate 21 is fixed inside the sound insulation cover 1 and divides the sound insulation cover 1 into front and rear cavities. The number of sound sensors 22 is multiple and arranged in an array on the front cavity surface of the fixing plate 21. The array accessories 23 are installed on the rear cavity surface of the fixing plate 21.

[0038] In this embodiment, the soundproof cover 1 is installed in front of the drone at an angle downwards with a vertical pitch angle of 45 degrees. The vertical pitch angle is the angle between the axis of the soundproof cover 1 and the horizontal plane of the drone.

[0039] To suppress the impact of drone aerodynamic noise, such as Figure 1 As shown, in this embodiment, a horn 11 (the "brimmed" at the front opening edge of the soundproof cover 1) is provided at the front opening edge. The outer side of the horn 11 has an arc-shaped cross-section, and the center of this arc is located at the farthest point P of the UAV's rotor deployment, and satisfies the following constraints:

[0040] ,

[0041] in, Let P be the point on the farthest side of the rotor deployment and C be the endpoint of the bell mouth 11. The line segment between point B, the lower front opening edge of the soundproof enclosure 1, and point C, the opening endpoint of the horn mouth 11, is... Let P be the point on the farthest side of the rotor deployment, and B be the edge of the lower front opening of the soundproof enclosure 1. Let λ be the wavelength corresponding to the lowest frequency of acoustic array imaging. Assuming the desired acoustic imaging frequency range in this example is 10kHz to 30kHz, then... The value is 0.034m.

[0042] like Figure 2 As shown, in this embodiment, the array arrangement refers to the multiple acoustic sensors 22 forming multiple concentric rings.

[0043] like Figure 2 As shown, in this embodiment, a camera 24 is arranged on the fixing plate 21 at the center of the annular shape.

[0044] In this embodiment, the soundproof cover 1 is made of rigid sound insulation material. Specifically, the rigid sound insulation material is 1.5mm aluminum alloy, which has the characteristics of being lightweight and having good sound insulation performance.

[0045] In this embodiment, the inner wall of the soundproof enclosure 1 is covered with a layer of sound-insulating material, and the outer wall is covered with a layer of sound-absorbing material. The rear cavity of the soundproof enclosure 1 is filled with sound-absorbing material. In this embodiment, the sound-absorbing material is damping sound-insulating felt or polyester fiber sound-absorbing cotton.

[0046] like Figure 1 As shown, this embodiment also provides a rotary-wing unmanned aerial vehicle (UAV), including a UAV body 3. A suspension connecting rod 4 is provided on the lower side of the UAV body 3, and the aforementioned acoustic array sound insulation device suitable for UAV use is installed and fixed on the suspension connecting rod 4. The mass of the suspension connecting rod 4 is included in the total mass of the acoustic array sound insulation device to meet the rated load limit requirements of the UAV.

[0047] Figure 5The sound pressure level at 1m directly below the drone (DJI M300) at different altitudes in this embodiment is shown. The drone noise has obvious logarithmic attenuation characteristics, and the extension and retraction stroke of the electric telescopic rod will affect the average signal strength collected by each sound sensor 22 in the sound sensor array 2. Similarly, the soundproof cover 1 is installed in front of the drone at an angle downwards and the vertical pitch angle will also affect the average signal strength collected by each sound sensor 22 in the sound sensor array 2. Therefore, as an optional implementation, the suspension connecting rod 4 in this embodiment is an electric telescopic rod (e.g., a linear motor can be used). The suspension connecting rod 4 is equipped with an electric turntable with an encoder. The electric turntable and the electric telescopic rod are respectively connected to a sound acquisition and adjustment controller. The sound acquisition and adjustment controller is used to control the electric turntable and the electric telescopic rod to adjust the height and angle of the sound array sound insulation device carried by the UAV, and is connected to the UAV for communication. The adjustment target is to make the average signal strength collected by each sound sensor 22 in the sound sensor array 2 reach the maximum value. For example: S101, retract the electric telescopic rod to the initial state; S102, determine whether the electric telescopic rod has reached the maximum extension stroke. If the maximum extension stroke has been reached, jump to step S104; otherwise, extend the electric telescopic rod by a preset extension step. If the signal strength is too high, proceed to step S103; S103: Control the electric turntable to rotate from the designated 0-degree position with a preset rotation step size. At each position, obtain the average signal strength from each sound sensor 22 in the sound sensor array 2 via the drone and record it in a tripartite array <extension stroke, rotation angle, average signal strength>. If the electric turntable completes one revolution, proceed to step S102; S104: Among all tripartites <extension stroke, rotation angle, average signal strength>, find the tripartite array with the largest average signal strength, and use its extension stroke and rotation angle as the optimal extension stroke and rotation angle. Control the electric turntable to rotate to the optimal rotation angle and control the electric telescopic rod to extend to the optimal extension stroke and maintain a fixed position via the sound acquisition and adjustment controller. Besides the average signal strength, other sound indicators can be used as needed. For example, a noise separation algorithm can be used to detect and separate various types of noise, such as drone rotor noise and wind noise. Using the minimum noise level as the indicator, the optimal extension stroke and rotation angle can be selected, achieving the same goal. It should be noted that noise separation algorithms are existing and well-known methods. Various machine learning methods using Mel-frequency cepstral coefficients (MFCC) and support vector machines (SVM), blind source separation (BSS) methods, and adaptive noise-blind separation (aNBS) methods can be adopted as needed.

[0048] like Figure 6As shown, this embodiment also provides a design method for the aforementioned acoustic array sound insulation device suitable for use on drones, including the following steps:

[0049] S1. Determine the outer shell size of the soundproof cover 1 based on the outer contour of the acoustic sensor array 2. Assuming the acoustic array is circular with a diameter of 10cm, the outer shell cross-section of the soundproof cover is preferably circular (or can be optimized to a shape with less aerodynamic noise) with an inner diameter of 12cm.

[0050] S2, determine the depth of the rear cavity of the soundproof enclosure 1 according to the size of the array accessory 23 (such as power management board, signal transmission module, etc.);

[0051] S3, determine the depth of the front cavity of the soundproof cover 1 based on the viewing angle of the camera 24; in this embodiment, determine the front length based on the viewing angle of the optical sensor of the acoustic array. Preferably, a reserved space of at least 5 degrees of viewing angle (α) or at least 10 mm is reserved for installing sound-absorbing and insulating materials, such as... Figure 4 As shown;

[0052] S4, determine the vertical pitch angle of the soundproof enclosure 1; the soundproof enclosure is oriented parallel to the front of the drone and diagonally downward, preferably 45 degrees horizontally downward, so as to achieve multi-angle detection by controlling the drone's up and down, horizontal movement and horizontal rotation, which is also beneficial to the design of the soundproof enclosure 1.

[0053] S5. Taking the furthest point P of the UAV's rotor as the center and the outer edge of the front opening of the soundproof cover 1 as the starting point A, draw an arc line with a specified central angle as the outer wall of the horn 11, satisfying the following constraints:

[0054] ,

[0055] in, Let P be the point on the farthest side of the rotor deployment and C be the endpoint of the bell mouth 11. The line segment between point B, the lower front opening edge of the soundproof enclosure 1, and point C, the opening endpoint of the horn mouth 11, is... Let P be the point on the farthest side of the rotor deployment, and B be the edge of the lower front opening of the soundproof enclosure 1. The wavelength corresponding to the lowest frequency of the acoustic array imaging is determined, and the opening of the horn 11 is connected to the inner edge of the front opening of the soundproof cover 1 to form a complete cross-section of the horn 11, thereby determining the structure of the horn 11; specifically, in this embodiment, based on the foremost position (point P) of the front rotor of the UAV, an arc of 20° is drawn forward from point P along the upper edge of the soundproof cover A to form the "brimmed cap" (horn 11) of the soundproof cover 1 to further improve the sound insulation performance;

[0056] S6. Based on the height of the drone body above the ground and the size of the soundproof cover 1 when the drone is parked, determine the installation positions of the soundproof cover 1 and the suspension connecting rod 4, so that the distance d between the lower part of the soundproof cover 1 and the ground when the drone is parked is not less than the preset safety distance; for example, in this embodiment, the preset safety distance is 1cm to prevent collisions.

[0057] S7, determine the rigid sound insulation material of the soundproof cover 1; in this embodiment, the rigid sound insulation material is specifically selected as 1.5mm aluminum alloy, which has the characteristics of light weight and good sound insulation performance.

[0058] S8, determine the material and thickness of the sound insulation material layer wrapped on the inner wall of the soundproof cover 1 and the sound absorption material layer wrapped on the outer wall, and determine the material and thickness of the sound absorption material filled in the rear cavity of the soundproof cover 1; in this embodiment, the soundproof cover is filled with 1cm of sound-absorbing and sound-insulating material inside, the outer side is sound-absorbing material, and the inner side is sound-insulating material. In this embodiment, 1mm sound insulation material and 8mm sound absorption material are preferred, such as environmentally friendly damping sound insulation felt and polyester fiber sound-absorbing cotton;

[0059] S9 determines whether the overall mass of the sound array sound insulation device meets the rated load of the drone. If the overall mass of the sound array sound insulation device does not meet the rated load of the drone, proceed to step S1 to adjust the design of the sound array sound insulation device; otherwise, the design of the sound array sound insulation device is considered complete, and the process ends and exits. Through this step, the mass of each component is considered to ensure that the overall mass of the soundproof enclosure does not exceed the rated load of the drone. If it does, optimization designs such as replacing the drone or reducing structural weight can be considered.

[0060] The sound array sound insulation device design method of this embodiment utilizes the spectral difference between UAV noise and discharge point noise, as well as the spatial position difference relative to the sound array, and adopts a combination of sound insulation and sound absorption to design a reasonable sound insulation structure. The beneficial effects are: (1) The method is fast in designing sound insulation structures, the process is clear, the implementation difficulty is low, and the effect is obvious. (2) The method has strong universality and can be applied to different application scenarios where different rotor UAVs are equipped with sound arrays that require sound insulation treatment.

[0061] The above description is merely a preferred embodiment 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 also be considered within the scope of protection of the present invention.

Claims

1. A design method for a sound insulation device for an acoustic array mounted on an unmanned aerial vehicle (UAV), characterized in that, The sound array sound insulation device includes a sound insulation cover (1), and a sound sensor array (2) is provided inside the sound insulation cover (1). The sound sensor array (2) includes a fixing plate (21), sound sensors (22), and array accessories (23). The array accessories (23) include part or all of the power board and signal transmission module. The fixing plate (21) is fixed inside the sound insulation cover (1) and divides the sound insulation cover (1) into front and rear cavities. The number of sound sensors (22) is multiple and arranged in an array on the front cavity surface of the fixing plate (21). The array accessories (23) are installed on the rear cavity surface of the fixing plate (21). A horn mouth (11) is provided at the front opening edge of the sound insulation cover (1). The outer side of the horn mouth (11) has an arc-shaped cross-section, and the center of the arc is located at the farthest point P of the UAV rotor deployment. The design method includes the following steps: S1, determine the outer shell size of the soundproof cover (1) based on the outer contour of the acoustic sensor array (2); S2, determine the depth of the rear cavity of the soundproof cover (1) according to the size of the array accessory (23); S3, determine the depth of the front cavity of the soundproof cover (1) based on the view of the camera (24); S4, determine the vertical pitch angle of the soundproof enclosure (1); S5, with the farthest point P of the UAV's rotor deployment as the center, and the outer edge of the front opening of the soundproof cover (1) as the starting point A, draw an arc line with a specified central angle as the outer wall of the horn mouth (11) and satisfy the following constraints: ， in, The line segment between the farthest point P of the rotor deployment and the end point C of the horn (11) opening, The line segment between point B, the lower front opening edge of the soundproof enclosure (1), and point C, the opening endpoint of the horn mouth (11), Let P be the point on the farthest side of the rotor deployment and B be the point on the lower edge of the front opening of the soundproof cover (1). The wavelength corresponding to the lowest frequency of the acoustic array imaging is determined, and the opening of the horn (11) is connected to the inner edge of the front opening of the soundproof cover (1) to form a complete cross-section of the horn (11), thereby determining the structure of the horn (11). S6. Based on the height of the drone body from the ground and the size of the soundproof cover (1) when the drone is parked, determine the installation position of the soundproof cover (1) and the suspension connecting rod (4) so ​​that the distance d between the lower part of the soundproof cover (1) and the ground when the drone is parked is not less than the preset safety distance. S7, determine the rigid sound insulation material of the soundproof cover (1); S8, determine the material and thickness of the sound insulation material layer wrapped on the inner wall and the sound absorption material layer wrapped on the outer wall of the soundproof cover (1), and determine the material and thickness of the sound absorption material filling the rear cavity of the soundproof cover (1). S9. Determine whether the overall quality of the sound array sound insulation device meets the rated load index of the drone. If the overall quality of the sound array sound insulation device does not meet the rated load index of the drone, then jump to step S1 to adjust the design of the sound array sound insulation device. Otherwise, determine that the design of the sound array sound insulation device is complete, end and exit.

2. The design method for a sound insulation device for an acoustic array mounted on a UAV according to claim 1, characterized in that, The soundproof cover (1) is installed in front of the drone at an angle downwards with a vertical pitch angle of 45 degrees. The vertical pitch angle is the angle between the axis of the soundproof cover (1) and the horizontal plane of the drone.

3. The design method for a sound insulation device for an acoustic array mounted on a UAV according to claim 1, characterized in that, The array arrangement refers to the arrangement of multiple acoustic sensors (22) forming multiple concentric rings.

4. The design method for a sound insulation device for an acoustic array mounted on a UAV according to claim 3, characterized in that, A camera (24) is arranged at the center of the annular shape on the fixed plate (21).

5. The design method for a sound insulation device for an acoustic array mounted on a UAV according to claim 1, characterized in that, The soundproof cover (1) is made of rigid soundproof material.

6. The design method for a sound insulation device for an acoustic array mounted on a UAV according to claim 5, characterized in that, The inner wall of the soundproof cover (1) is covered with a layer of sound-insulating material, and the outer wall is covered with a layer of sound-absorbing material. The rear cavity of the soundproof cover (1) is filled with sound-absorbing material.

7. The design method for a sound insulation device for an unmanned aerial vehicle (UAV) based on claim 6, characterized in that, The sound-absorbing material is a damping sound insulation felt or polyester fiber sound-absorbing cotton.

8. A rotary-wing unmanned aerial vehicle (UAV), comprising a UAV body (3), characterized in that, The lower side of the UAV body (3) is provided with a suspension connecting rod (4), and a sound array sound insulation device obtained by the design method of the sound array sound insulation device suitable for UAV as described in any one of claims 1 to 7 is installed and fixed on the suspension connecting rod (4).

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