Parachute three-dimensional reconstruction device and method based on multi-view information fusion

Abstract

The invention discloses a parachute three-dimensional reconstruction device and method based on multi-view information fusion, and the device comprises a wind tunnel module which is used for blowing a parachute to achieve parachute opening, the center of the tail end of a wind tunnel inlet of the wind tunnel module is the installation position of a parachute cord, and a space for unfolding a parachute canopy is formed between the wind tunnel inlet and a wind tunnel outlet; the observation module is used for comprehensively observing the parachute from multiple orientations and comprises laser radars and reflecting mirror surfaces which are distributed in different orientations in front of and behind the parachute, and each laser radar can observe the parachute in a self view angle and can also observe the parachute in a reflection view angle of one or more corresponding reflecting mirror surfaces; and the data fusion module can receive the point cloud data of each observation view angle of each laser radar in real time and reconstruct the shape of the parachute in a three-position manner in real time, so that complete and dynamic deformation data in the parachute opening process of the parachute are obtained. According to the method, the dynamic change in the parachute opening process can be captured in real time, the data precision is ensured, and the missing of key data points is avoided.

Description

Technical Field

[0001] This invention relates to parachute deployment, and more specifically to a parachute three-dimensional reconstruction device and method based on multi-view information fusion. Background Technology

[0002] Experiments and applications show that during the deployment of a full-size parachute, problems such as parachute flipping, failure of the canopy to deploy smoothly, incomplete canopy inflation, and asymmetrical deployment may occur. In other words, the parachute may undergo complex dynamic deformation during actual airdrops. To gain a deeper understanding of the fluid-structure interaction deformation mechanism during deployment, sufficient parachute canopy deformation and aerodynamic data must be obtained. Due to the rapid dynamic response and complex folding patterns of the parachute deployment process, to more accurately record the entire dynamic behavior of the parachute during straightening and inflation, it is necessary to analyze in detail the changes in the length of the parachute connecting lines and the changes in the canopy during inflation and expansion. These data help establish a precise correspondence between the instantaneous shape of the canopy and the parachute's drag characteristics.

[0003] However, current research on the parachute deployment process mainly relies on fluid-structure interaction simulation analysis and empirical or semi-empirical formula calculations. These simulations and experiences cannot fully account for the complex morphological changes during deployment, especially when the canopies are partially obscured. It is difficult to effectively monitor various possible states such as canopy damage, parachute line entanglement, and asymmetric deployment, thus failing to obtain realistic data. Although there are physical experiments on parachute deployment, they are limited to overall recording and observation, and cannot obtain detailed deformation data. Summary of the Invention

[0004] The purpose of this invention is to provide a parachute 3D reconstruction device based on multi-view information fusion, and a parachute 3D reconstruction method based on multi-view information fusion. This application can capture the dynamic changes during the parachute opening process in real time, ensure data accuracy, and avoid the loss of key data points caused by the deployment of the parachute canopy.

[0005] The technical solution adopted in this invention is: A 3D parachute reconstruction device based on multi-view information fusion includes a wind tunnel module, an observation module, and a data fusion module. The wind tunnel module is used to blow air onto the parachute to achieve parachute deployment. It includes an aligned and spaced wind tunnel inlet and outlet. The center of the end of the wind tunnel inlet is the installation position of the parachute lines, and the space between the wind tunnel inlet and outlet is for the parachute canopy to deploy. The observation module is used to comprehensively observe the parachute from multiple directions. It includes lidars and reflectors distributed at different positions in front of and behind the parachute. Each lidar can observe the parachute from its own perspective and also from the reflection perspective of one or more corresponding reflectors. The data fusion module can receive point cloud data from each observation perspective of each lidar in real time and reconstruct the shape of the parachute in 3D in real time, thereby obtaining complete and dynamic deformation data during the parachute deployment process.

[0006] Preferably, a horizontal first lidar is provided near the center of the parachute. The first lidar has a corresponding first and second reflective mirror. The first and second reflective mirrors are symmetrically arranged on the left and right sides of the first lidar. The first lidar, the first reflective mirror, and the second reflective mirror are rotated 90° around the center to obtain the position of the second lidar and the corresponding third and fourth reflective mirrors. A third lidar is provided at a lower left 45° position behind the parachute, tilted 45° to the lower left. The third lidar has a corresponding fifth reflective mirror. The fifth reflective mirror is located at a lower right 45° position behind the parachute and tilted 45° to the lower right. The third lidar and the fifth reflective mirror are symmetrical about the vertical centerline to obtain the position of the fourth lidar and the corresponding sixth reflective mirror.

[0007] Preferably, a column is provided at the end of the wind tunnel entrance, with the top of the column located at the center of the wind tunnel entrance and serving as the installation position for the parachute lines.

[0008] Preferably, some of the lidar is mounted on a column, while the remaining lidar is mounted in a wind tunnel and on the ground.

[0009] Preferably, the reflective mirrors are mounted on the wind tunnel, the ground, and the support, respectively.

[0010] Preferably, the parachute is installed downstream of the wind tunnel.

[0011] Preferably, the reflective mirror is a thin-film mirror.

[0012] Preferably, the lidar is a 128-line mechanical lidar with mutually perpendicular primary and secondary fields of view, the primary field of view being 360° and the secondary field of view being +15° to -25°.

[0013] A 3D reconstruction method for parachutes based on multi-view information fusion is proposed. The parachute is placed in a wind tunnel, and the parachute lines are installed at the center of the wind tunnel entrance. The space between the wind tunnel entrance and exit is for the parachute canopy to deploy. LiDARs and reflective mirrors are distributed at different positions in front of and behind the parachute. Each LiDAR can observe the parachute from its own perspective and from the reflection perspective of one or more corresponding reflective mirrors, so that all LiDARs can observe the parachute comprehensively from multiple directions. When the wind tunnel blows on the parachute to open it, the method receives point cloud data from each observation perspective of each LiDAR in real time and reconstructs the shape of the parachute in 3D in real time, thereby obtaining complete and dynamic deformation data of the parachute during the opening process.

[0014] Preferably, the wind tunnel monitors complete and dynamic environmental data, including air pressure and flow velocity, while the parachute is being deployed. The deformation data and environmental data are then combined for analysis.

[0015] The beneficial effects of this invention are: This device utilizes a wind tunnel module to blow air onto the parachute to achieve parachute opening. The airflow generated by the wind tunnel flows through the parachute canopy, which, propelled by the airflow and influenced by internal gas pressure, gradually unfolds. Finally, the airflow flows back to the environment through the wind tunnel outlet. The device uses a lidar as the observation equipment for the parachute opening process. The lidar determines the distance to an object by emitting a laser beam and measuring the time it takes for the laser to reflect back from the object's surface. Its resolution and measurement speed meet accuracy requirements even during the extremely short opening process, thus providing real-time capture of dynamic changes during parachute opening and ensuring data accuracy. The device uses reflective mirrors to increase the lidar's observation angle, allowing for comprehensive observation of both the front and back of the parachute during simulated opening. This avoids the loss of key data points caused by canopy unfolding and also avoids the cost of using numerous lidar units. Therefore, this device can provide experimental verification data for parachute opening numerical simulation, clarifying the impact of canopy shape changes on drag characteristics, opening dynamic loads, and opening robustness, thereby providing guidance for the design of the opening process and the optimization of parachute folding and packaging methods. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the parachute three-dimensional reconstruction device based on multi-view information fusion in this invention.

[0017] Figure 2 This is a schematic diagram of the wind tunnel module in this invention.

[0018] Figure 3 This is a schematic diagram of the parachute in this invention.

[0019] Figure 4 This is a schematic diagram illustrating the working process of the parachute three-dimensional reconstruction device based on multi-view information fusion in this invention.

[0020] In the diagram: 11-First lidar; 12-Second lidar; 13-Upper lidar; 14-Fourth lidar; 21-First reflecting mirror; 22-Second reflecting mirror; 23-Third reflecting mirror; 24-Fourth reflecting mirror; 25-Fifth reflecting mirror; 26-Sixth reflecting mirror; 31-Wind tunnel entrance; 32-Column; 33-Wind tunnel exit; 41-Parachute lines; 42-Parachute canopy. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. These terms are used only for the convenience of describing this application and for 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 application. Furthermore, the terms "first xxx," "second xxx," "third xxx," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0026] Example 1 This embodiment discloses a parachute 3D reconstruction device based on multi-view information fusion, such as... Figures 1 to 4 As shown, it includes a wind tunnel module, an observation module, and a data fusion module; as Figure 1 , Figure 2 and Figure 4 As shown, the wind tunnel module is used to blow air onto the parachute to enable its deployment. It includes aligned and spaced-apart wind tunnel inlets 31 and 33. The center of the end of the wind tunnel inlet 31 is the mounting position for the parachute lines 41. The space between the wind tunnel inlet 31 and the wind tunnel outlet 33 is for the parachute canopy 42 to deploy. Figure 1 and Figure 4 As shown, the observation module is used to observe the parachute from multiple directions. It includes lidars and reflectors distributed in different directions in front of and behind the parachute. Each lidar can observe the parachute from its own perspective and from the reflection perspective of one or more corresponding reflectors. The data fusion module can receive point cloud data from each observation perspective of each lidar in real time and reconstruct the shape of the parachute in real time in 3D, thereby obtaining complete and dynamic deformation data during the parachute opening process.

[0027] The device uses a wind tunnel module to blow air onto the parachute to open it. The airflow generated by the wind tunnel flows through the parachute canopy. The canopy is pushed by the airflow and affected by the internal gas pressure, and gradually begins to unfold. Finally, the airflow flows back to the environment through the wind tunnel outlet 33.

[0028] The device uses lidar as an observation device for the parachute opening process. Lidar determines the distance to an object by emitting a laser beam and measuring the time it takes for the laser to reflect back from the object's surface. Its resolution and measurement speed can meet the accuracy requirements even in the extremely short opening process, thus providing real-time capture of dynamic changes during the opening process and ensuring data accuracy.

[0029] This device utilizes a reflective mirror to increase the observation angle of the lidar, enabling a comprehensive observation of both the front and back of the parachute during the simulated parachute opening process. This avoids the loss of key data points caused by the unfolding of the parachute canopy, and also avoids the cost of using numerous lidar units.

[0030] Therefore, this device can provide experimental verification data for numerical simulation of parachute opening, clarify the influence of changes in the shape of the parachute canopy on drag characteristics, opening dynamic load, and opening robustness, and thus provide guidance for the design of the opening process and the optimization of parachute folding and packaging methods.

[0031] In this embodiment, preferably, as follows: Figure 1 and Figure 4As shown, a horizontal first lidar 11 is located near the center of the parachute. The first lidar 11 has a corresponding first reflective mirror 21 and a second reflective mirror 22. The first reflective mirror 21 and the second reflective mirror 22 are symmetrically arranged on the left and right sides of the first lidar 11. The first lidar 11, the first reflective mirror 21 and the second reflective mirror 22 are rotated 90° around the center to obtain the position of the second lidar 12 and the corresponding third reflective mirror 23 and fourth reflective mirror 24. A third lidar 13 is located at a 45° lower left position behind the parachute and tilted 45° to the lower left. The third lidar 13 has a corresponding fifth reflective mirror 25. The fifth reflective mirror 25 is located at a 45° upper right position behind the parachute and tilted 45° to the lower right. The third lidar 13 and the fifth reflective mirror 25 are symmetrical about the vertical centerline to obtain the position of the fourth lidar 14 and the corresponding sixth reflective mirror 26. Using four lidar units with reflecting mirrors is equivalent to the observation angles of more than a dozen lidar units, saving a significant amount of money. The first lidar unit 11 has three observation angles: one self-view and two reflected view angles, with the two reflected view angles having equal and symmetrical field of view. Similarly, the second lidar unit 12 also has three observation angles; however, their observation surfaces are perpendicular to each other (the first lidar unit 11 focuses on horizontal full coverage observation, while the second lidar unit 12 focuses on vertical full coverage observation). With a total of six observation angles, the first lidar unit 11 and the second lidar unit 12 can completely observe the parachute opening process from the front, although normally the shape of the parachute's front can be observed... The system can also detect the shape of the back of the parachute. However, during the opening process, there may be issues such as the parachute flipping or wrinkling, so the shape of the front and back of the parachute may not be consistent. Therefore, a lidar and a reflector are also installed behind the parachute. The third lidar 13 has two observation angles, namely a self-view and a reflection view. Similarly, the fourth lidar 14 also has two observation angles. However, the observation surfaces of the two are perpendicular to each other. The third lidar 13 and the fourth lidar 14 together have four observation angles, which can completely observe the opening process of the back of the parachute. The third lidar 13 and the fourth lidar 14 are tilted to avoid obstructing the airflow behind the parachute, thereby affecting the natural opening shape of the parachute.

[0032] In this embodiment, preferably, as follows: Figure 1 , Figure 2 and Figure 4 As shown, a column 32 is provided at the end of the wind tunnel entrance 31. The top of the column 32 is located at the center of the wind tunnel entrance 31 and is the installation position of the parachute rope 41. Some lidars are installed on the column 32, and the remaining lidars are installed in the wind tunnel and on the ground respectively.

[0033] In this embodiment, the reflective mirrors are mounted on the wind tunnel, the ground, and the support, respectively.

[0034] In this embodiment, preferably, the parachute is installed downstream of the wind tunnel, which can better simulate the aerodynamic conditions in actual airdrops, ensuring that the parachute experiences a stable airflow, while avoiding the turbulence and uneven airflow that may exist at the wind tunnel entrance, thereby providing more accurate aerodynamic performance data.

[0035] In this embodiment, preferably, the reflecting mirror is a thin-film mirror.

[0036] In this embodiment, preferably, the lidar is a 128-line mechanical lidar, which has a primary field of view and a secondary field of view that are perpendicular to each other. The primary field of view is 360° and the secondary field of view is +15° to -25°.

[0037] Example 2 This embodiment discloses a three-dimensional reconstruction method for parachutes based on multi-view information fusion. The parachute is placed in a wind tunnel, and the parachute lines are installed at the center of the wind tunnel entrance. The space between the wind tunnel entrance and exit is for the parachute canopy to deploy. LiDARs and reflective mirrors are distributed at different positions in front of and behind the parachute. Each LiDAR can observe the parachute from its own perspective and from the reflection perspective of one or more corresponding reflective mirrors, so that all LiDARs can observe the parachute comprehensively from multiple directions. When the wind tunnel blows on the parachute to open it, it receives point cloud data from each observation perspective of each LiDAR in real time and reconstructs the shape of the parachute in three dimensions in real time, thereby obtaining complete and dynamic deformation data during the parachute opening process.

[0038] In this embodiment, preferably, the wind tunnel monitors complete and dynamic environmental data when the parachute opens, including air pressure and flow velocity. The deformation data and environmental data are then combined for analysis.

[0039] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A parachute 3D reconstruction device based on multi-view information fusion, characterized in that: It includes a wind tunnel module, an observation module, and a data fusion module. The wind tunnel module is used to blow air onto the parachute to enable it to open. It includes an aligned and spaced wind tunnel inlet and a wind tunnel outlet. The center of the end of the wind tunnel inlet is the installation position for the parachute lines. The space between the wind tunnel inlet and the wind tunnel outlet is for the parachute canopy to deploy. The observation module is used to observe the parachute from multiple directions. It includes lidar and reflector surfaces distributed in different directions in front of and behind the parachute. Each lidar can observe the parachute from its own perspective as well as from the reflection perspective of one or more corresponding reflector surfaces. The data fusion module can receive point cloud data from each observation angle of each lidar in real time and reconstruct the shape of the parachute in real time in three dimensions, thereby obtaining complete and dynamic deformation data during the parachute opening process.

2. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 1, characterized in that: A horizontal first lidar is positioned near the center of the parachute. The first lidar has a corresponding first and second reflective mirror. The first and second reflective mirrors are symmetrically arranged on the left and right sides of the first lidar. The first lidar, the first reflective mirror, and the second reflective mirror are rotated 90° around the center to obtain the position of the second lidar and the corresponding third and fourth reflective mirrors. A third lidar is positioned 45° to the lower left and 45° to the left of the parachute. The third lidar has a corresponding fifth reflective mirror. The fifth reflective mirror is positioned 45° to the upper right and 45° to the lower right of the parachute. The third lidar and the fifth reflective mirror are symmetrical about the vertical centerline to obtain the position of the fourth lidar and the corresponding sixth reflective mirror.

3. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 1, characterized in that: A pillar is installed at the end of the wind tunnel entrance, with the top of the pillar located at the center of the wind tunnel entrance and the installation position for the parachute lines.

4. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 3, characterized in that: Some of the lidar units are mounted on pillars, while the rest are mounted in the wind tunnel and on the ground.

5. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 1, characterized in that: The reflective mirrors are mounted on the wind tunnel, the ground, and the support frame, respectively.

6. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 1, characterized in that: The parachute is installed downstream of the wind tunnel.

7. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 1, characterized in that: The reflective mirror is made of thin film.

8. The parachute 3D reconstruction device based on multi-view information fusion as described in claim 1, characterized in that: The lidar uses a 128-line mechanical lidar with mutually perpendicular primary and secondary fields of view. The primary field of view is 360°, and the secondary field of view is +15° to -25°.

9. A method for 3D reconstruction of a parachute based on multi-view information fusion, characterized in that: The parachute is placed in a wind tunnel, with the parachute lines installed at the center of the wind tunnel entrance. The space between the wind tunnel entrance and exit is for the parachute canopy to deploy. LiDARs and reflectors are distributed at different positions in front of and behind the parachute. Each LiDAR can observe the parachute from its own perspective as well as from the reflection perspective of one or more corresponding reflectors, allowing all LiDARs to observe the parachute comprehensively from multiple directions. When the wind tunnel blows on the parachute to open it, it receives point cloud data from each observation perspective of each LiDAR in real time and reconstructs the shape of the parachute in 3D in real time, thereby obtaining complete and dynamic deformation data during the parachute opening process.

10. The parachute 3D reconstruction method based on multi-view information fusion as described in claim 9, characterized in that: The wind tunnel monitors complete and dynamic environmental data during parachute deployment, including air pressure and flow velocity. The deformation data and environmental data are then combined for analysis.

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