A method, device and system for measuring relative pose of an umbrella wing aircraft

Abstract

The application provides a winged parachute aircraft relative pose measurement method, device and system, and relates to the technical field of winged parachute aircrafts. The application filters out target point cloud data corresponding to the reflective tape from initial point cloud data collected by a multi-line laser sensor by comprehensively utilizing reflection intensity information and spatial position information, and determines the pose of the winged parachute relative to the nacelle according to the target point cloud data, fully utilizes the characteristics of the multi-line laser sensor, such as a large field of view angle, small data volume and distance measurement not affected by light conditions, overcomes the technical defects of the existing visual measurement scheme, such as a limited field of view angle, large data volume and susceptibility to light interference, and realizes non-contact and all-weather stable measurement of the pose of the winged parachute relative to the nacelle, thereby providing reliable data basis for motion analysis and flight control of the winged parachute aircraft.

Description

Technical Field

[0001] This invention relates to the field of paraglider technology, and in particular to a method, apparatus and system for measuring the relative attitude of a paraglider. Background Technology

[0002] A paraglider is a new type of unmanned aerial vehicle (UAV) consisting of two main parts: a paraglider and a pod, which are connected by parachute lines. The paraglider can take off from the ground or be launched from an aircraft. During flight, it is propelled forward by a motor-driven propeller in the pod, while lift is provided by the ram-air paraglider above. Compared to traditional fixed-wing UAVs of similar size, paragliders offer advantages such as a higher payload ratio, longer cruising time, lower manufacturing cost, and easier packaging, folding, and transportation.

[0003] During the flight of a paraglider, the relative position and attitude of the paraglider and pod change within a certain range due to factors such as trailing edge pull-down control, wind interference, and the method of connection. Therefore, describing the motion of a paraglider requires establishing a multibody dynamics model, typically assuming that the paraglider and pod are each rigid bodies connected by a suspension constraint. However, because the paraglider is a flexible structure, most measuring equipment, such as satellite positioning modules and inertial measurement modules, cannot be directly mounted on the flexible wing surface or paraglider lines and must be installed inside the pod. This means that direct measurement of the paraglider's motion can only obtain the pod's motion data, not the paraglider's motion data in three-dimensional space. Therefore, how to introduce non-contact measurement methods to solve the problem of measuring the position and attitude of the paraglider relative to the pod is a significant technical challenge faced by those skilled in the art when analyzing the motion of paragliders.

[0004] Currently, existing non-contact parachute attitude measurement solutions typically involve mounting an upward-looking (viewing upwards) monocular or binocular camera above the pod and using image recognition algorithms to obtain the real-time attitude of the parachute relative to the pod. However, this method has the following technical drawbacks: First, it requires the camera to have a sufficiently large field of view, and most non-customized ordinary cameras cannot meet the requirement of capturing the parachute across the entire angular range in space; second, the amount of image data to be stored during flight is enormous, placing high demands on airborne data storage and transmission capabilities; third, the image recognition algorithm is greatly affected by lighting conditions, with a significant decrease in recognition accuracy in strong or low light environments. Summary of the Invention

[0005] The purpose of this invention is to provide a method, device and system for measuring the relative attitude of a paraglider, so as to overcome the problems of limited field of view, large amount of data and susceptibility to light interference in the prior art.

[0006] In a first aspect, the present invention provides a method for measuring the relative attitude of a paraglider aircraft, the paraglider aircraft including a paraglider and a pod, the lower surface of the paraglider being provided with reflective tape, and the upper surface of the pod being equipped with a multi-line laser sensor, the multi-line laser sensor being used to collect point cloud data of the paraglider; the method includes: Acquire initial point cloud data collected by a multi-line laser sensor during flight; Based on the reflection intensity and spatial location information in the initial point cloud data, the target point cloud data corresponding to the reflective tape is obtained from the initial point cloud data; Based on the target point cloud data, determine the target pose data of the parachute relative to the pod.

[0007] In an optional implementation, target point cloud data corresponding to the reflective tape is obtained from the initial point cloud data based on the reflection intensity information and spatial location information in the initial point cloud data, including: Spatial range filtering is performed on the initial point cloud data to retain point cloud data whose spatial location information is within a preset spatial range; The spatial range filtered point cloud data is then subjected to reflection intensity filtering, retaining point cloud data whose reflection intensity information is within a preset intensity range; Point cloud data within a preset effective flight time range is selected from the filtered point cloud data based on reflection intensity and used as the target point cloud data corresponding to the reflective tape.

[0008] In an optional implementation, the target pose data of the parachute relative to the pod is determined based on the target point cloud data, including: Based on the target point cloud data, the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center of the parachute are calculated. Based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center, the six-degree-of-freedom pose data of the parachute relative to the pod is calculated and used as the target pose data.

[0009] In an optional embodiment, reflective tape is affixed to the parachute rope connections and control rope connections on the lower surface of the parachute. The parachute rope connections include multiple sets of connections between the parachute ropes and the lower surface of the parachute. Based on the target point cloud data, the three-dimensional coordinates of the parachute's geometric center and aerodynamic center are calculated, including: For each frame of point cloud data in the target point cloud data, calculate the average value of the three-dimensional coordinates of each point cloud in that frame of point cloud data to obtain the three-dimensional coordinates of the geometric center corresponding to that frame of point cloud data. The geometric center three-dimensional coordinates of the sub-point cloud corresponding to the reflective tape at the parachute rope connection point in the first frame of point cloud data are used as the aerodynamic center three-dimensional coordinates corresponding to the first frame of point cloud data.

[0010] In an optional implementation, the six-degree-of-freedom pose data of the parachute relative to the pod is calculated based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center, and is used as the target pose data, including: For each frame of point cloud data in the target point cloud data, calculate the covariance matrix of the point cloud data of that frame relative to the three-dimensional coordinates of its geometric center, and solve the eigenvector of the covariance matrix to obtain the three-axis orientation matrix corresponding to the point cloud data of that frame. Based on the three-dimensional coordinates of the geometric center and the three-axis orientation matrix corresponding to the point cloud data of this frame, calculate the six-degree-of-freedom pose data of the parachute relative to the pod corresponding to the point cloud data of this frame. The target pose data is obtained by summing the six degrees of freedom pose data corresponding to the point cloud data of each frame.

[0011] In an optional implementation, after determining the target pose data of the parachute relative to the pod based on the target point cloud data, the method further includes: Temporal filtering and denoising are performed on the target pose data to obtain the denoised target pose data.

[0012] Secondly, the present invention provides a relative attitude measurement device for a paraglider aircraft. The paraglider aircraft includes a paraglider and a pod. Reflective tape is provided on the lower surface of the paraglider, and a multi-line laser sensor is installed on the upper surface of the pod. The multi-line laser sensor is used to collect point cloud data of the paraglider. The device includes: The data acquisition module is used to acquire the initial point cloud data collected by the multi-line laser sensor during flight; The point cloud filtering module is used to obtain the target point cloud data corresponding to the reflective tape from the initial point cloud data based on the reflection intensity information and spatial location information in the initial point cloud data. The pose calculation module is used to determine the target pose data of the parachute relative to the pod based on the target point cloud data.

[0013] Thirdly, the present invention provides a relative attitude measurement system for a paraglider aircraft, including a multi-line laser sensor, an airborne computer, and a ground station computer; A multi-line laser sensor is installed on the upper surface of the pod of the paraglider to collect point cloud data of the paraglider's parachute; reflective tape is installed on the lower surface of the paraglider. The onboard computer is installed in the pod and connected to the multi-line laser sensor. It is used to store the point cloud data collected by the multi-line laser sensor during flight and to provide the stored point cloud data to the ground station computer after the flight. The ground station computer includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the paraglider relative attitude measurement method of any of the aforementioned embodiments.

[0014] In an optional implementation, the system also includes a transparent protective cover, which is mounted on the upper surface of the pod and covers the multi-line laser sensor. Multi-line laser sensors include mechanically rotating scanning laser sensors.

[0015] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the paraglider relative attitude measurement method of any of the foregoing embodiments.

[0016] This invention provides a method, device, and system for measuring the relative attitude of a paraglider. By comprehensively utilizing reflection intensity information and spatial position information from the initial point cloud data collected by a multi-line laser sensor, the target point cloud data corresponding to the reflective tape is selected, and the attitude of the paraglider relative to the pod is determined accordingly. This fully utilizes the advantages of multi-line laser sensors, such as a large field of view, small data volume, and distance measurement unaffected by lighting conditions. It overcomes the technical shortcomings of existing visual measurement schemes, such as limited field of view, large data volume, and susceptibility to lighting interference. This invention achieves non-contact, all-weather, stable measurement of the paraglider's attitude relative to the pod, providing a reliable data foundation for the motion analysis and flight control of paragliders. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for measuring the relative attitude of a paraglider aircraft, provided in an embodiment of the present invention; Figure 2 A schematic diagram of the application position of reflective tape provided in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the installation of a multi-line laser sensor in a paraglider aircraft, as provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of solving the direction vector of a point cloud in a two-dimensional plane, provided by an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of a relative attitude measurement device for a paraglider aircraft provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a paraglider relative attitude measurement system provided in an embodiment of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0020] The following technical problems exist in the existing technology: (1) Existing vision-based parachute pose measurement schemes are limited by the field of view and are difficult to capture the full-angle motion of the parachute in space; (2) The existing solution has an excessive amount of data storage, which puts a lot of pressure on the airborne storage and transmission system; (3) The existing scheme is sensitive to lighting conditions, and the measurement accuracy is unstable under different lighting conditions.

[0021] To address the aforementioned technical problems, embodiments of the present invention provide a method, apparatus, and system for measuring the relative attitude of a paraglider, offering a more effective method for offline calculation of the position and attitude of the paraglider relative to the pod during the flight of a paraglider.

[0022] To facilitate understanding of this embodiment, a method for measuring the relative attitude of a paraglider aircraft disclosed in this embodiment of the invention will first be described in detail.

[0023] This invention provides a method for measuring the relative attitude of a paraglider aircraft, which can be executed by a computer device with data processing capabilities (such as a ground station computer). See also Figure 1 The diagram shows a flowchart of a method for measuring the relative attitude of a paraglider aircraft. The method mainly includes the following steps S110 to S130: Step S110: Acquire the initial point cloud data collected by the multi-line laser sensor during flight.

[0024] A paraglider consists of a parachute and a pod, which are connected by parachute lines. Because the parachute is a flexible structure, most measuring equipment, such as satellite positioning modules and inertial measurement modules, cannot be directly mounted on the flexible wing surface or parachute lines and must be installed inside the pod. This means that direct measurement of the paraglider's motion can only obtain motion data from the pod, and not from the parachute's motion data in three-dimensional space.

[0025] To address the aforementioned issues, this invention involves attaching reflective tape to specific locations on the underside of the parachute and installing a multi-line laser sensor on the upper surface of the pod. The multi-line laser sensor is used to collect point cloud data from the parachute. The reflective tape enhances the laser reflection intensity at specific locations, facilitating the identification of key positions on the underside of the parachute from the point cloud data.

[0026] like Figure 2 As shown, the thick boxes indicate the locations where reflective tape is applied. Specifically, the paraglider includes four groups of parachute lines (A, B, C, and D, with the intersection point of group A being the A Riser, group B being the B Riser, and groups C and D being the C Riser) and trailing edge control lines (intersection point being the Brake Handle). The control lines are used to control left and right directions. Reflective tape is applied to the connections between each group of parachute lines and the lower wing surface along the center chord direction. Reflective tape is also applied to the connections between group B parachute lines and the lower wing surface along the spanwise direction of the lower wing surface, as well as to the connections between the control lines and the lower wing surface. It should be noted that, to avoid excessive density, Figure 2 The paracords are all displayed in a mirror image on one side, but in reality, each group of paracords is symmetrically distributed along the stretching direction.

[0027] In one possible implementation, the parachute area is approximately 20m². 2 The paracord length is approximately 7m, and the reflective tape applied at this ratio is approximately 30mm x 30mm in size.

[0028] The multi-line laser sensor can be a mechanically rotating scanning laser sensor with a horizontal scanning field of view of 360 degrees and a vertical scanning field of view of 90 degrees, satisfying a full hemispherical field of view. Its ranging capability exceeds the maximum range of motion of the parachute relative to the pod during normal flight. Optionally, the multi-line laser sensor can be a mechanically rotating scanning 96-line laser sensor with a field of view of 360°×90°, a ranging capability of 30m (10% reflectivity), a data frame rate of 10Hz, and a dual-echo mode (strongest echo + last echo). The measurement method is TOF (Time of Flight). Here, 30m (10% reflectivity) means a range ≥30m under a target with 10% reflectivity.

[0029] like Figure 3 As shown, the coordinate system of the multi-line laser sensor is defined as follows: The multi-line laser sensor is installed at the origin. , The axis is parallel to the pod body axis and points rearward. The axis is perpendicular to the axial direction of the pod body. The axes are determined using a right-handed coordinate system. The pod coordinate system is defined as follows: The origin is located at the point where the inertial navigation system is installed at the center of mass of the pod. , The axis points forward along the pod's axis. The axis is perpendicular to the pod body axis and points downwards. The axes are determined using a right-handed coordinate system. The parachute coordinate system is defined as follows: The aerodynamic center of the parachute is located at the origin. , The axis points towards the leading edge along the chord of the parachute. The axis is perpendicular to the parachute chord and points downwards. The axis is determined according to the right-hand rule.

[0030] like Figure 3 As shown, a flat surface is selected above the pod, and a multi-line laser sensor is installed and fixed with three-point bolts, ensuring that the multi-line laser sensor is located within the longitudinal symmetry plane of the paraglider pod. Axis-aligned pod for paraglider aircraft axis( The axis is parallel to (axis), multi-line laser sensor Shaft and pod Axis parallel and opposite, multi-line laser sensor Axis-aligned pod for paraglider aircraft axis( shaft and (Axes parallel and opposite). Measuring the three-dimensional coordinates of the multi-line laser sensor relative to the pod's center of mass in the pod coordinate system. Ideally An onboard computer is fixedly installed inside the pod, and a multi-line laser sensor is connected to the computer's network port. During the flight of the paraglider, the multi-line laser sensor continuously collects point cloud data of the paraglider to obtain initial point cloud data, which can then be transmitted to the onboard computer for storage.

[0031] The specific operation procedure for the paraglider is as follows: Before powering on the multi-line laser sensor and the onboard computer, the operator wears laser-protective goggles and then performs the power-on operation. After powering on, the onboard computer's time is first adjusted to UTC (Coordinated Universal Time) standard time, accurate to 0.1 seconds, and then the laser point cloud data is continuously transmitted to the onboard computer via the network port. During flight, the trailing edge pull-down control and propeller thrust control are recorded according to UTC standard time. After the paraglider lands, the operator, wearing laser-protective goggles, approaches the aircraft, first operates the onboard computer to save the laser point cloud data, and then performs the power-off operation for both the multi-line laser sensor and the onboard computer. After power-off, the goggles are removed.

[0032] Step S120: Based on the reflection intensity information and spatial location information in the initial point cloud data, obtain the target point cloud data corresponding to the reflective tape from the initial point cloud data.

[0033] This step aims to filter out the point cloud data corresponding to the reflective tape from the initial point cloud data collected by the multi-line laser sensor through a dual filtering method, and use it as the input for subsequent pose calculation.

[0034] In some possible embodiments, step S120 may include: performing spatial range filtering on the initial point cloud data to retain point cloud data whose spatial location information is within a preset spatial range; performing reflection intensity filtering on the spatially range-filtered point cloud data to retain point cloud data whose reflection intensity information is within a preset intensity range; selecting point cloud data within a preset effective flight time range from the reflection intensity-filtered point cloud data and using it as the target point cloud data corresponding to the reflective tape.

[0035] Specifically, the initial point cloud data is first filtered by spatial range, using the predicted motion range of the parachute in space as a constraint. By setting a preset spatial range, invalid point clouds located outside the parachute's motion range are removed, retaining only the area where the parachute's underside surface is located. In one specific implementation, the coordinate system of the multi-line laser sensor is defined as follows: The multi-line laser sensor is installed at the origin. Using the predicted range of paraglider motion in space as a constraint, only [the paraglider] is retained in the point cloud image. Axis range [-2m, 5m] Axis range [-5m, 5m] Point clouds on the underwing surface of the parachute within the range of [3m, 8m].

[0036] Next, the spatially filtered point cloud data is filtered for reflection intensity. Since reflective tape has high laser reflection intensity, by setting a preset intensity range, point clouds with high reflection intensity can be retained, thus filtering out the point clouds corresponding to the reflective tape. In one specific implementation, laser reflection intensity is used as a constraint condition to retain only the underwing surface point clouds of the parachute with reflection intensity in the range [180, 255] in the point cloud image.

[0037] Finally, point cloud data within a preset effective flight time range is selected from the filtered point cloud data based on reflection intensity. By setting the effective flight time, invalid point cloud data collected during takeoff and landing or abnormal time periods are eliminated, retaining only the point cloud data from the stable flight phase or the target analysis period, which is then used as the target point cloud data corresponding to the reflective tape. The target point cloud data is saved as a spatial three-dimensional coordinate format file, and the UTC time of the first frame of point cloud data is recorded. .

[0038] It should be noted that the execution order of spatial range filtering, reflection intensity filtering, and time-of-flight filtering can be adjusted according to the actual situation and is not fixed. This embodiment only uses the order of spatial range filtering first, then reflection intensity filtering, and finally time-of-flight filtering as an example for illustration, but the scope of protection of this invention is not limited to this.

[0039] Step S130: Determine the target pose data of the parachute relative to the pod based on the target point cloud data.

[0040] This step is the core of the method, aiming to use the target point cloud data corresponding to the selected reflective tape to calculate the six-degree-of-freedom pose data of the parachute relative to the pod.

[0041] In some possible embodiments, step S130 above may include: calculating the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center of the parachute based on the target point cloud data; and calculating the six-degree-of-freedom pose data of the parachute relative to the pod based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center, as the target pose data.

[0042] Specifically, the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center of the parachute are first calculated based on the target point cloud data. The geometric center reflects the spatial distribution center of the reflective tape point cloud on the lower surface of the parachute, while the aerodynamic center reflects the center of action of the parachute's aerodynamic forces.

[0043] In one possible implementation, reflective tape is affixed to both the parachute rope connections and control rope connections on the lower surface of the parachute. The parachute rope connections include multiple sets of connections between the parachute ropes and the lower surface of the parachute. Based on this, the process of calculating the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center from the target point cloud data can include: for each frame of point cloud data in the target point cloud data, calculating the average of the three-dimensional coordinates of each point cloud in that frame to obtain the three-dimensional coordinates of the geometric center corresponding to that frame; and using the three-dimensional coordinates of the geometric center of the sub-point cloud corresponding to the set set of reflective tape at the parachute rope connections in the first frame of point cloud data as the three-dimensional coordinates of the aerodynamic center corresponding to the first frame of point cloud data.

[0044] For each frame of point cloud data, the average of the three-dimensional coordinates of all point clouds is calculated and used as the three-dimensional coordinates of the geometric center of the parachute in that frame of point cloud data. The formula for calculating the three-dimensional coordinates of the geometric center can be: ; In the formula, N The total number of selected points in this frame of point cloud data. i Number the point cloud. The geometric centers of the parachute in the multi-line laser sensor coordinate system are respectively... axis, axis, The coordinate values ​​of the axis. The first i A point cloud in the coordinate system of a multi-line laser sensor axis, axis, The coordinate values ​​of the axis.

[0045] For the aerodynamic center, the geometric center three-dimensional coordinates of the sub-point cloud corresponding to the reflective tape at the parachute rope connection point in the first frame of point cloud data are selected as the aerodynamic center three-dimensional coordinates corresponding to the first frame of point cloud data. In a specific implementation, such as Figure 2 As shown, the three-dimensional coordinates of the center of group B in the first frame of point cloud data are selected as the aerodynamic center position of the parachute in that frame of point cloud data. Then, the vector pointing from the geometric center to the aerodynamic center in the multi-line laser sensor coordinate system of this frame of point cloud data is calculated. : ; in, This represents the aerodynamic center position vector of the parachute in the multi-line laser sensor coordinate system of the first frame of point cloud data. This represents the geometric center position vector of the parachute in the multi-line laser sensor coordinate system of the first frame of point cloud data. It should be noted that the aerodynamic center coordinates of the remaining frames will be obtained sequentially after the parachute orientation is calculated.

[0046] In one possible implementation, the process of calculating the six-DOF pose data of the parachute relative to the pod based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center can include: for each frame of point cloud data in the target point cloud data, calculating the covariance matrix of the point cloud data frame relative to its three-dimensional coordinates of the geometric center, and solving for the eigenvectors of the covariance matrix to obtain the three-axis orientation matrix corresponding to the point cloud data frame; calculating the six-DOF pose data of the parachute relative to the pod corresponding to the point cloud data frame based on the three-dimensional coordinates of the geometric center and the three-axis orientation matrix corresponding to the point cloud data frame; and summing the six-DOF pose data corresponding to each frame of point cloud data to obtain the target pose data.

[0047] Specifically, based on Figure 3 The coordinate system defined in the image is used to calculate the direction vector of each selected point cloud data point relative to its geometric center position in each frame of point cloud data. ; in, In the multi-line laser sensor coordinate system, the first... i The direction vector of a point cloud relative to its geometric center In the multi-line laser sensor coordinate system, the first... i The position vector of a point cloud, This represents the position vector of the geometric center in the coordinate system of the multi-line laser sensor. N This represents the total number of point clouds in this frame of point cloud data.

[0048] Figure 4 This diagram illustrates the calculated direction vector of a point cloud in a two-dimensional plane, as shown below. Figure 4As shown, the Cartesian coordinate system has O as the origin, the horizontal axis as the X-axis, and the vertical axis as the Y-axis; the geometric center coordinates of the point cloud are (Xp, Yp); the point cloud data is distributed in the form of black dots, forming an ellipse; to calculate the principal directions (major axis / minor axis directions) of the point cloud, a local coordinate system X′Y′ is constructed, with its origin coinciding with the geometric center (Xp, Yp), the X′ axis along the major axis of the point cloud ellipse, and the Y′ axis along the minor axis. Based on this, to calculate the point cloud direction vector, the covariance matrix of the selected point cloud relative to the geometric center position in each frame of point cloud data is first calculated: ; Then solve the matrix. The feature vectors yield the three-axis orientation matrix of the point cloud data for this frame: ; in, This represents three eigenvectors. , , The three-axis direction matrix formed; Represents a matrix Perform eigenvalue decomposition and return the matrix. All feature vectors.

[0049] Arrange the three feature vectors according to the principal direction , , Arranged in order, if , , If the principal component of an eigenvector is negative, then the entire eigenvector is inverted to ensure that the matrix... All principal values ​​are positive, corresponding to the parachute coordinate system direction.

[0050] In a like Figure 3 In the specific embodiment shown, since the coordinate system of the multi-line laser sensor and the coordinate system of the pod have an inverse correspondence, the direction vector from the geometric center of the parachute to the aerodynamic center in the parachute coordinate system is calculated using the following formula: ; in, This represents the direction vector from the geometric center of the parachute to the aerodynamic center in the parachute coordinate system. This represents the direction vector from the geometric center of the parachute to the aerodynamic center in the coordinate system of the multi-line laser sensor.

[0051] Ideally The absolute value should be much smaller than and This proves that the multi-line laser sensor is installed in the correct orientation and has no lateral deviation.

[0052] Next, the three-axis position of the parachute aerodynamic center relative to the pod is calculated for each frame of point cloud data in the pod coordinate system. In one specific embodiment, since the multi-line laser sensor coordinate system and the pod coordinate system have an inverse correspondence, the following formula is used: ; in, This indicates the three-axis position of the parachute aerodynamic center relative to the pod in the pod coordinate system. In That is, the aforementioned In ; In That is, the three-dimensional coordinates of the aforementioned multi-line laser sensor relative to the center of mass of the pod in the pod coordinate system.

[0053] Simultaneously, the three-axis attitude angles of the parachute relative to the pod are calculated for each frame of point cloud data in the pod coordinate system. In one specific embodiment, since the multi-line laser sensor coordinate system and the pod coordinate system have an inverse correspondence, the following formula is used: ; in, This is the roll angle of the parachute relative to the pod (positive when the right side is downward). The pitch angle of the parachute relative to the pod (positive when the parachute is pointing upwards). The yaw angle of the parachute relative to the pod (positive for a right turn), indicated by the subscript. b Indicates the coordinate system of the pod; This represents the third eigenvector in the three-axis direction matrix; These represent the first eigenvector in the three-axis direction matrix in the laser sensor coordinate system. , , Components on the axis.

[0054] After obtaining the six-DOF pose data for each frame, denoising processing is also required. In some possible embodiments, after determining the target pose data of the parachute relative to the pod based on the target point cloud data, the method further includes: performing temporal filtering and denoising on the target pose data to obtain denoised target pose data.

[0055] Specifically, by examining the change in data at each time step relative to the previous time step, only data within a reasonable range is retained to remove noise. In one specific implementation, only reasonable data within the following ranges is retained: Finally, the attitude data of the parachute relative to the pod and its charts are obtained and output throughout the entire flight process.

[0056] In this embodiment of the invention, the target point cloud data corresponding to the reflective tape is selected from the initial point cloud data collected by the multi-line laser sensor by comprehensively utilizing reflection intensity information and spatial position information. Based on this, the attitude of the paraglider relative to the pod is determined. This fully utilizes the characteristics of the multi-line laser sensor, such as a large field of view, small data volume, and distance measurement unaffected by lighting conditions. It overcomes the technical defects of existing visual measurement schemes, such as limited field of view, large data volume, and susceptibility to lighting interference. This achieves non-contact, all-weather stable measurement of the attitude of the paraglider relative to the pod, providing a reliable data foundation for the motion analysis and flight control of paraglider aircraft.

[0057] Corresponding to the above-described method for measuring the relative attitude of a paraglider, this embodiment of the invention also provides a device for measuring the relative attitude of a paraglider. In this embodiment, the paraglider includes a paraglider and a pod. Reflective tape is provided on the lower surface of the paraglider, and a multi-line laser sensor is installed on the upper surface of the pod. The multi-line laser sensor is used to collect point cloud data of the paraglider. See also... Figure 5 The diagram shows a structural schematic of a relative attitude measurement device for a paraglider aircraft. The device includes: The data acquisition module 501 is used to acquire the initial point cloud data collected by the multi-line laser sensor during flight; The point cloud filtering module 502 is used to obtain the target point cloud data corresponding to the reflective tape from the initial point cloud data based on the reflection intensity information and spatial location information in the initial point cloud data. The pose calculation module 503 is used to determine the target pose data of the parachute relative to the pod based on the target point cloud data.

[0058] The paraglider relative attitude measurement device provided in this invention uses reflection intensity information and spatial position information to filter out the target point cloud data corresponding to the reflective tape from the initial point cloud data collected by the multi-line laser sensor, and determines the attitude of the paraglider relative to the pod accordingly. It makes full use of the characteristics of the multi-line laser sensor, such as large field of view, small data volume, and distance measurement not being affected by lighting conditions, and overcomes the technical defects of existing visual measurement schemes, such as limited field of view, large data volume, and susceptibility to lighting interference. It realizes non-contact, all-weather stable measurement of the paraglider's attitude relative to the pod.

[0059] Furthermore, the point cloud filtering module 502 is specifically used to: perform spatial range filtering on the initial point cloud data, retaining point cloud data whose spatial location information is within a preset spatial range; perform reflection intensity filtering on the spatially filtered point cloud data, retaining point cloud data whose reflection intensity information is within a preset intensity range; select point cloud data within a preset effective flight time range from the reflection intensity filtered point cloud data, and use it as the target point cloud data corresponding to the reflective tape.

[0060] Furthermore, the aforementioned pose calculation module 503 is specifically used to: calculate the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center of the parachute based on the target point cloud data; and calculate the six-degree-of-freedom pose data of the parachute relative to the pod based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center, as the target pose data.

[0061] Furthermore, reflective tape is affixed to the parachute rope connections and control rope connections on the lower surface of the parachute. The parachute rope connections include multiple sets of connections between the parachute ropes and the lower surface of the parachute. The pose calculation module 503 is also used to: calculate the average value of the three-dimensional coordinates of each point cloud in each frame of point cloud data in the target point cloud data, and obtain the three-dimensional coordinates of the geometric center corresponding to the frame of point cloud data; and take the three-dimensional coordinates of the geometric center of the sub-point cloud corresponding to the reflective tape at the set set of parachute rope connections in the first frame of point cloud data as the three-dimensional coordinates of the aerodynamic center corresponding to the first frame of point cloud data.

[0062] Furthermore, the pose calculation module 503 is also used to: calculate the covariance matrix of the point cloud data frame relative to the three-dimensional coordinates of its geometric center for each frame of point cloud data in the target point cloud data, and solve for the eigenvectors of the covariance matrix to obtain the three-axis orientation matrix corresponding to the frame of point cloud data; calculate the six-degree-of-freedom pose data of the parachute relative to the pod based on the three-dimensional coordinates of the geometric center and the three-axis orientation matrix corresponding to the frame of point cloud data; and summarize the six-degree-of-freedom pose data corresponding to each frame of point cloud data to obtain the target pose data.

[0063] Furthermore, the pose calculation module 503 is also used to: perform temporal filtering and denoising on the target pose data to obtain denoised target pose data.

[0064] The paraglider relative attitude measurement device provided in this embodiment has the same implementation principle and technical effect as the aforementioned paraglider relative attitude measurement method embodiment. For the sake of brevity, any parts not mentioned in the device embodiment can be referred to the corresponding content in the aforementioned method embodiment.

[0065] This invention also provides a relative attitude measurement system for a paraglider aircraft. See [link to related documentation]. Figure 6 The system includes a multi-line laser sensor 601, an airborne computer 602, and a ground station computer 603.

[0066] A multi-line laser sensor 601 is fixedly mounted on the upper surface of the pod of the paraglider to collect point cloud data of the paraglider. The multi-line laser sensor 601 can be a mechanically rotating scanning laser sensor with a horizontal scanning field of view of 360 degrees and a vertical scanning field of view of 90 degrees. Reflective tape is provided on the lower surface of the paraglider, and the reflective tape is attached to specific positions on the lower surface of the paraglider to enhance the laser reflection intensity at specific positions in order to calculate the aerodynamic center and three-axis direction matrix of the paraglider.

[0067] An onboard computer 602 is fixedly installed inside the pod and connected to a multi-line laser sensor 601. It stores point cloud data collected by the multi-line laser sensor 601 during flight and provides the stored point cloud data to a ground station computer 603 after flight. In one specific embodiment, the onboard computer 602 is connected to the multi-line laser sensor 601 via a network port with a data transmission rate of approximately 10 Mb / s. The onboard computer 602 also provides UTC standard time, accurate to 0.1 s, and records the trailing edge pull-down control and propeller thrust control quantities of the paraglider according to UTC standard time.

[0068] The ground station computer 603 includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the aforementioned paraglider relative attitude measurement method. The ground station computer 603 is used to store and execute the computer program, perform offline calculations on the point cloud data provided by the airborne computer 602, and output the attitude data and charts of the paraglider relative to the pod throughout the entire flight process.

[0069] Optionally, the system further includes a transparent protective cover, which is mounted on the upper surface of the pod and covers the multi-line laser sensor 601. The transparent protective cover protects the multi-line laser sensor 601 from scratches by parachute lines and impacts upon landing. In one specific embodiment, such as... Figure 3 As shown, the transparent protective cover is a highly transparent hemispherical acrylic protective cover, with the center of the cover aligned with the optical center of the multi-line laser sensor 601, and the transparent protective cover is provided with openings to allow the multi-line laser sensor 601 to dissipate heat normally.

[0070] The paraglider relative attitude measurement system provided in this invention collects point cloud data of the paraglider using a multi-line laser sensor. The onboard computer stores the point cloud data during flight, and a ground station computer performs offline calculations, achieving non-contact measurement of the paraglider's attitude relative to the pod. This system offers advantages such as a large measurement field of view, small data storage requirements, measurement unaffected by lighting conditions, simple system configuration, and minimal impact on the paraglider's flight performance during the measurement process.

[0071] Compared with the prior art, the beneficial effects of the embodiments of the present invention include: (1) The measurement field of view is large. The multi-line laser sensor meets the full field of view of the hemispherical surface and can capture the large range of motion of the parachute relative to the pod without being limited by the field of view. (2) The data storage capacity is small. The point cloud data of the multi-line laser sensor is about one-tenth of the data captured by the traditional binocular camera, which significantly reduces the pressure on airborne data storage and transmission. (3) The measurement is not affected by lighting conditions. The multi-line laser sensor is based on the TOF time-of-flight method for ranging, and can maintain stable measurement accuracy in strong light, weak light and nighttime environments. (4) The system has a simple structure, requires fewer measuring devices and only needs to be installed on a rigid pod, is easy to operate, has fast data calculation and good visualization effect; (5) The measurement process has almost no impact on the flight performance of the paraglider itself; (6) The measurement targets are diverse, and corresponding data can be obtained for specific targets (such as parachute rope straps or trailing edge of parachute).

[0072] This invention also provides a computer-readable storage medium storing a computer program. When executed by a processor, this computer program performs the paraglider relative attitude measurement method described in the preceding method embodiments. The computer-readable storage medium includes various media capable of storing program code, such as a USB flash drive, portable hard drive, read-only memory (ROM), RAM, magnetic disk, or optical disk.

[0073] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0074] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "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.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the relative attitude of a paraglider aircraft, characterized in that, The paraglider includes a paraglider and a pod. The lower surface of the paraglider is covered with reflective tape, and the upper surface of the pod is equipped with a multi-line laser sensor for collecting point cloud data from the paraglider. The method includes: Acquire the initial point cloud data collected by the multi-line laser sensor during flight; Based on the reflection intensity information and spatial location information in the initial point cloud data, the target point cloud data corresponding to the reflective tape is obtained from the initial point cloud data; Based on the target point cloud data, the target pose data of the paraglider relative to the pod is determined.

2. The method according to claim 1, characterized in that, The step of obtaining the target point cloud data corresponding to the reflective tape from the initial point cloud data based on the reflection intensity information and spatial location information in the initial point cloud data includes: Spatial range filtering is performed on the initial point cloud data to retain point cloud data whose spatial location information is within a preset spatial range; The spatial range filtered point cloud data is then subjected to reflection intensity filtering, retaining point cloud data whose reflection intensity information is within a preset intensity range; Point cloud data within a preset effective flight time range is selected from the filtered point cloud data based on reflection intensity and used as the target point cloud data corresponding to the reflective tape.

3. The method according to claim 1, characterized in that, Determining the target pose data of the paraglider relative to the pod based on the target point cloud data includes: Based on the target point cloud data, the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center of the parachute are calculated. Based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center, the six-degree-of-freedom pose data of the parachute relative to the pod is calculated and used as the target pose data.

4. The method according to claim 3, characterized in that, The reflective tape is affixed to the parachute rope connections and control rope connections on the lower surface of the parachute. The parachute rope connections include multiple sets of connections between the parachute ropes and the lower surface of the parachute. The calculation of the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center of the parachute based on the target point cloud data includes: For each frame of point cloud data in the target point cloud data, calculate the average value of the three-dimensional coordinates of each point cloud in that frame of point cloud data to obtain the three-dimensional coordinates of the geometric center corresponding to that frame of point cloud data. The geometric center three-dimensional coordinates of the sub-point cloud corresponding to the reflective tape at the parachute rope connection point in the first frame of point cloud data are used as the aerodynamic center three-dimensional coordinates corresponding to the first frame of point cloud data.

5. The method according to claim 4, characterized in that, The step of calculating the six-DOF pose data of the parachute relative to the pod based on the three-dimensional coordinates of the geometric center and the three-dimensional coordinates of the aerodynamic center, as the target pose data, includes: For each frame of point cloud data in the target point cloud data, calculate the covariance matrix of the frame of point cloud data relative to the three-dimensional coordinates of its geometric center, and solve the eigenvector of the covariance matrix to obtain the three-axis orientation matrix corresponding to the frame of point cloud data. Based on the geometric center three-dimensional coordinates and three-axis orientation matrix corresponding to the point cloud data of this frame, the six-degree-of-freedom pose data of the parachute relative to the pod corresponding to the point cloud data of this frame is calculated; The target pose data is obtained by summing the six-degree-of-freedom pose data corresponding to the point cloud data of each frame.

6. The method according to any one of claims 1-5, characterized in that, After determining the target pose data of the paraglider relative to the pod based on the target point cloud data, the method further includes: The target pose data is subjected to temporal filtering and denoising to obtain denoised target pose data.

7. A relative attitude measurement device for a paraglider aircraft, characterized in that, The paraglider includes a paraglider and a pod. The lower surface of the paraglider is covered with reflective tape, and the upper surface of the pod is equipped with a multi-line laser sensor for collecting point cloud data from the paraglider. The device includes: The data acquisition module is used to acquire the initial point cloud data collected by the multi-line laser sensor during flight; The point cloud filtering module is used to obtain the target point cloud data corresponding to the reflective tape from the initial point cloud data based on the reflection intensity information and spatial location information in the initial point cloud data. The pose calculation module is used to determine the target pose data of the paraglider relative to the pod based on the target point cloud data.

8. A relative attitude measurement system for a paraglider aircraft, characterized in that, Includes multi-line laser sensors, airborne computers, and ground station computers; The multi-line laser sensor is installed on the upper surface of the pod of the paraglider and is used to collect point cloud data of the paraglider's parachute; the lower surface of the paraglider is provided with reflective tape. The airborne computer is installed in the pod and connected to the multi-line laser sensor. It is used to store the point cloud data collected by the multi-line laser sensor during flight and to provide the stored point cloud data to the ground station computer after the flight ends. The ground station computer includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the paraglider relative attitude measurement method according to any one of claims 1-6.

9. The system according to claim 8, characterized in that, The system also includes a transparent protective cover, which is installed on the upper surface of the pod and covers the multi-line laser sensor; The multi-line laser sensor includes a mechanically rotating scanning laser sensor.

10. A computer-readable storage medium storing a computer program thereon, characterized in that, The computer program, when executed by the processor, performs the paraglider relative attitude measurement method according to any one of claims 1-6.

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