A method for quickly screening UAV circular trajectory SAR echo data
By measuring the latitude and longitude of the target center and the known angular position using UAVs, calculating the deviation angle, and converting the circular trajectory SAR echo data into polar coordinates centered on the target, the problem of GPS mapping difficulties is solved, and efficient data filtering and analysis are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING QIWEI TECH CO LTD
- Filing Date
- 2024-11-27
- Publication Date
- 2026-05-29
Smart Images
Figure BDA0005157823280000031 
Figure BDA0005157823280000051 
Figure FDA0005157823250000021
Abstract
Description
Technical Field
[0001] This invention relates to data filtering methods, and more particularly, to a method for rapidly filtering SAR echo data of a UAV flying in a circular trajectory around a target. Background Technology
[0002] In today's rapidly developing technological era, the application of drones in various industries has sparked a wave of industrial innovation. Drone-based ground-penetrating synthetic aperture radar (SAR) combines drone and radar technology to perform high-resolution imaging and RCS measurements of the ground. This technology can be applied in military, civilian, and scientific fields, such as 3D terrain imaging, monitoring glacier changes, or searching for missing persons. Its advantages include high efficiency, accuracy, flexibility, and economy, enabling large-area imaging tasks to be completed in a short time. Furthermore, its low line-of-sight advantage avoids the impact of factors such as weather and terrain.
[0003] High-precision positioning is a key technology in UAV SAR testing. Traditionally, total stations or GPS are used for positioning, but their accuracy is affected by various environmental factors. However, with the continuous improvement of GPS technology, high-precision positioning in UAV SAR testing has become possible. For example, by using differential GPS technology and joint positioning with base stations and rover stations, centimeter-level or even millimeter-level measurement accuracy can be provided.
[0004] However, the development of UAV SAR testing technology relies heavily on data analysis and processing. Much data analysis is based on the UAV's GPS for filtering, but because GPS cannot be effectively mapped to the target's coordinates relative to itself, this adds significant difficulties to subsequent data filtering and analysis.
[0005] Therefore, how to quickly filter and analyze SAR echo data, improve the efficiency of data analysis and the reliability of the results, has become a technical problem that urgently needs to be solved in SAR echo data analysis and processing. Summary of the Invention
[0006] The purpose of this invention is to propose a method for rapid filtering of UAV circular trajectory SAR echo data, which enables the extraction and analysis of data from any angle of the target itself, greatly facilitating the data filtering process for users and improving the efficiency of subsequent data analysis and processing.
[0007] To achieve this objective, the present invention adopts the following technical solution:
[0008] A method for rapid filtering of UAV circular trajectory SAR echo data includes:
[0009] Target center latitude and longitude acquisition step S110:
[0010] Control the drone to fly directly above the center of the target to be tested, measure and record the latitude and longitude of the center point c1 of the target to be tested jw1, where the center point c1 of the target to be tested refers to the target center driven by the test requirements, not the geometric center of the target;
[0011] Step S120: Acquisition of target's known angle, position, latitude, and longitude.
[0012] Control the drone to fly to any position s1 in the direction of a known angle a1 of the target to be measured, and measure and record the latitude and longitude jw2 of the arbitrary position s1;
[0013] Difference calculation step S130:
[0014] Based on the latitude and longitude jw1 of the center point c1 of the target to be measured and the latitude and longitude jw2 of the position s1 of the known angle a1, calculate the angle b1 of the position s1 relative to the center point c1 of the target to be measured in the Earth coordinate system. Then, based on the known angle a1 and the calculated angle b1, calculate the deviation angle p1 between the target coordinate system and the Earth coordinate system. The calculation formula is: p1=b1-a1.
[0015] Circular trajectory SAR test procedure S140:
[0016] According to the established SAR test plan, the UAV is controlled to conduct a circular trajectory SAR test on the target, and at the same time, a list of latitude and longitude information jwN synchronized with the data is recorded. jwN is composed of a series of latitude and longitude points recorded by the UAV at regular intervals during the circular trajectory flight test. Based on the known latitude and longitude of the target center jw1, the latitude and longitude list jwN in the circular trajectory is converted into an angle list bN in the Earth coordinate system.
[0017] Circular trajectory conversion step S150:
[0018] The angle list bN of the circular trajectory in the Earth coordinate system is converted into the angle list aN of the target coordinate system by subtracting the deviation value p1. That is, p1 is subtracted from each angle in the angle list bN. The calculation formula is: aN = bN - p1.
[0019] Quick data filtering step S160:
[0020] Select data from appropriate angles based on the needs of data analysis and processing.
[0021] Optionally, in step S120,
[0022] The known angle a1 is an angle with the center of the target itself as the coordinate system. The size of this angle can be arbitrarily selected. The UAV can measure and record latitude and longitude information jw2 at any position in the direction of the known angle a1.
[0023] Optionally, in step S150,
[0024] Perform a modulo operation on the converted angle aN to convert aN into data between 0 and 360 degrees.
[0025] Optionally, step S160 specifically includes:
[0026] All the latitude and longitude information of the circular trajectory SAR echo data is converted into 0-360 data centered on the target. Users can select a segment or multiple segments of the data for processing according to their data analysis and processing needs.
[0027] Optionally, the known angle is any known angle between 0 and 360 degrees.
[0028] Optionally, in the deviation value calculation step S130,
[0029] Angle b1 is calculated using formula (1) through the position s1 of the center point c1 to be measured and the known angle a1:
[0030]
[0031] Where x is the angle to be calculated, w1 is the latitude of jw1, w2 is the latitude of jw2, j1 is the longitude of jw1, and j2 is the longitude of jw2.
[0032] Optionally, in circular trajectory SAR test step S140,
[0033] The conversion method for the angle list bN is as follows: calculate the latitude and longitude of each point in jwN and the latitude and longitude of the target origin using formula (1), and the conversion results of all points are finally composed of the list bN.
[0034] Optionally, the drone may be a fixed-wing drone or a multi-rotor drone, supporting real-time latitude and longitude recording.
[0035] Optionally, the real-time latitude and longitude recording function can be: during the test, the UAV can directly transmit the real-time latitude and longitude to the test radar, and the test radar can synchronously record the latitude and longitude information, or the UAV can generate a latitude and longitude information with a synchronization tag with the echo data in real time.
[0036] Optionally, the SAR echo data is echo data generated by any synthetic aperture radar test, and the target to be tested is any identifiable target on land or sea.
[0037] Optionally, the synchronous recording of latitude and longitude information means that for each echo data generated by the test, the latitude and longitude information at the time the echo data was generated can be found.
[0038] Optionally, when the real-time performance of latitude and longitude information does not meet the frequency of the test data, the latitude and longitude information of the data can be obtained by linear interpolation.
[0039] The present invention has the following advantages:
[0040] This invention utilizes a drone to measure the latitude and longitude (GPS) information of the target's center point and the latitude and longitude (GPS) information of the target's known arbitrary angle position. This process converts the GPS information from circular trajectory SAR into polar coordinate information centered on the target itself. This conversion allows users to extract and analyze data from any angle of the target, greatly simplifying the data filtering process and improving the efficiency of subsequent data analysis and processing. Attached Figure Description
[0041] Figure 1 This is a schematic diagram of a target at a known angle at any position according to a specific embodiment of the present invention;
[0042] Figure 2 This is a schematic diagram of angle calculation in the Earth coordinate system according to a specific embodiment of the present invention;
[0043] Figure 3 This is a schematic diagram illustrating the calculation of the deviation angle according to a specific embodiment of the present invention;
[0044] Figure 4 This is a schematic diagram of a circular trajectory flight SAR test according to a specific embodiment of the present invention;
[0045] Figure 5 This is a flowchart of a method for rapidly filtering SAR echo data of UAV circular trajectories according to a specific embodiment of the present invention.
[0046] The technical features referred to by the reference numerals in the figure are as follows:
[0047] 1. Target to be tested; 2. Unmanned aerial vehicle (UAV). Detailed Implementation
[0048] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.
[0049] The main features of this invention are: using a UAV to measure the latitude and longitude of the target center and the latitude and longitude of any position at a known angle of the target, calculating the deviation angle between the target coordinate system and the Earth coordinate system, performing a circular trajectory SAR flight test, and obtaining latitude and longitude information synchronized with the data; converting the latitude and longitude of any known angle into an angle centered on the target, and performing data filtering and analysis based on the converted angle information.
[0050] Further, see Figure 4 The experimental conditions for a rapid screening method of UAV circular trajectory SAR echo data are shown, namely, a schematic diagram of circular trajectory flight SAR test, including target 1 and UAV 2. UAV 2 needs to be equipped with a radar system for SAR testing.
[0051] SAR stands for Synthetic Aperture Radar. It utilizes the principle of synthetic aperture to achieve high-resolution microwave imaging, possessing multiple characteristics such as all-weather, all-day operation, high resolution, and wide swath.
[0052] Circular trajectory SAR refers to a standard circular SAR test conducted by an UAV with the target center as the center. Test data and GPS data are recorded simultaneously during the test.
[0053] See Figure 5 The screening method includes the following steps:
[0054] Target center latitude and longitude acquisition step S110:
[0055] Control the drone 2 to fly directly above the center of the target to be tested, measure and record the latitude and longitude jw1 of the center point c1 of the target to be tested 1, where the center point c1 of the target to be tested 1 refers to the target center driven by the test requirements, not the geometric center of the target.
[0056] Step S120: Acquisition of target's known angle, position, latitude, and longitude.
[0057] like Figure 1 As shown, the drone 2 is controlled to fly to any position s1 in the direction of the known angle a1 of the target 1 to be measured, and the latitude and longitude jw2 of the arbitrary position s1 are measured and recorded.
[0058] Wherein, the known angle a1 is the angle with the center of the target 1 as the coordinate system. The size of this angle can be arbitrarily selected. The UAV 2 can measure and record the latitude and longitude information jw2 at any position in the direction of the known angle a1. If there are multiple known angle directions for the target, any one of them can be selected.
[0059] Deviation value calculation step S130:
[0060] Based on the latitude and longitude jw1 of the center point c1 of the target to be measured and the latitude and longitude jw2 of the position s1 with known angle a1, the angle b1 of point s1 relative to the center point c1 of the target to be measured in the Earth coordinate system is calculated. The calculation method is to perform trigonometric function operations using the latitude and longitude of the two points, such as... Figure 2 As shown, the trigonometric function algorithm is shown in formula (1). Then, based on the known angle a1 and the calculated angle b1, the deviation angle p1 between the target coordinate system and the Earth coordinate system is calculated using the formula: p1 = b1 - a1. Figure 3 As shown.
[0061]
[0062] Where x is the angle to be calculated, w1 is the latitude of jw1, w2 is the latitude of jw2, j1 is the longitude of jw1, and j2 is the longitude of jw2.
[0063] Circular trajectory SAR test procedure S140:
[0064] like Figure 4 As shown, according to the set SAR test plan, the UAV is controlled to conduct a circular trajectory SAR test on the target, and at the same time, the latitude and longitude information list jwN synchronized with the data is recorded to obtain the circular trajectory SAR echo data. Here, jwN is composed of a series of latitude and longitude points recorded by the UAV at regular intervals during the circular trajectory flight test. Based on the known latitude and longitude of the target center c1 jw1, the latitude and longitude list jwN in the circular trajectory is converted into an angle list bN in the Earth coordinate system.
[0065] The conversion method is to perform trigonometric function operations on the latitude and longitude of each point in jwN and the latitude and longitude of the target origin one by one. The algorithm is shown in formula (1). The conversion results of all points are finally composed into a list bN.
[0066] The UAV can enter the circular trajectory from any position of the target 1 for SAR testing. The UAV's flight radius and flight altitude can be set according to the test requirements.
[0067] Circular trajectory conversion step S150:
[0068] To convert the list of angles bN in the Earth coordinate system of the circular trajectory into the list of angles aN in the target coordinate system by subtracting the deviation value p1, we subtract p1 from each angle in the list of angles bN. The calculation formula is: aN = bN - p1.
[0069] Optionally, the angle list aN can be in polar coordinates.
[0070] Furthermore, the converted angle aN may contain data that is less than 0 degrees or greater than 360 degrees. Therefore, this invention performs a modulo operation on the converted angle aN to convert aN into data between 0 and 360 degrees.
[0071] Quick data filtering step S160:
[0072] Select data from appropriate angles based on the needs of data analysis and processing.
[0073] Specifically, the latitude and longitude information of all circular trajectory SAR echo data is converted into 0-360 data centered on the target. Users can select one or more segments of the data for processing according to their data analysis and processing needs.
[0074] In this invention, the drone can be a fixed-wing drone or a multi-rotor drone, and supports real-time latitude and longitude recording function.
[0075] The SAR echo data is the echo data generated by arbitrary synthetic aperture radar testing, and the target to be tested can be any identifiable target on land or sea.
[0076] The known angle can be any known angle between 0 and 360 degrees.
[0077] The real-time latitude and longitude recording function is as follows: during the test, the UAV can directly transmit real-time latitude and longitude to the test radar, and the test radar synchronously records the latitude and longitude information, or the UAV can generate latitude and longitude information with a synchronization tag with the echo data in real time.
[0078] The synchronous recording of latitude and longitude information means that for each echo data generated by the test, the latitude and longitude information at the time the echo data was generated can be found.
[0079] When the real-time performance of latitude and longitude information does not meet the frequency of the test data, the latitude and longitude information of the data can be obtained through linear interpolation.
[0080] In summary, the present invention has the following advantages:
[0081] This invention utilizes unmanned aerial vehicle (UAV) measurement to determine the latitude and longitude of the target's center and the latitude and longitude of its known angles. This quantifies the target's known angles and their deviations. Based on these deviations, the latitude and longitude of the acquired target circular trajectory SAR echo data can be converted into target azimuth angles (e.g., polar coordinates) with the target center as the origin. This allows for rapid filtering and analysis based on the target's azimuth information during data analysis and processing. Therefore, it improves data filtering efficiency, facilitates subsequent data processing and analysis by users, and enhances the accuracy of the system's target detection signal analysis.
[0082] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.
Claims
1. A method for rapid filtering of UAV circular trajectory SAR echo data, characterized in that, Includes the following steps: Target center latitude and longitude acquisition step S110: Control the drone 2 to fly directly above the center of the target to be tested, measure and record the latitude and longitude jw1 of the center point c1 of the target to be tested 1, where the center point c1 of the target to be tested 1 refers to the target center driven by the test requirements, not the geometric center of the target; Step S120: Acquisition of target's known angle, position, latitude, and longitude. Control the drone 2 to fly to any position s1 in the direction of the known angle a1 of the target 1 to be measured, and measure and record the latitude and longitude jw2 of the arbitrary position s1; Difference calculation step S130: Based on the latitude and longitude jw1 of the center point c1 of the target to be measured and the latitude and longitude jw2 of the position s1 of the known angle a1, calculate the angle b1 of the position s1 relative to the center point c1 of the target to be measured in the Earth coordinate system. Then, based on the known angle a1 and the calculated angle b1, calculate the deviation angle p1 between the target coordinate system and the Earth coordinate system. The calculation formula is: p1=b1-a1. Circular trajectory SAR test procedure S140: According to the established SAR test plan, the UAV is controlled to conduct a circular trajectory SAR test on the target, and at the same time, a list of latitude and longitude information jwN synchronized with the data is recorded. jwN is composed of a series of latitude and longitude points recorded by the UAV at regular intervals during the circular trajectory flight test. Based on the known latitude and longitude of the target center jw1, the latitude and longitude list jwN in the circular trajectory is converted into an angle list bN in the Earth coordinate system. Circular trajectory conversion step S150: The angle list bN of the circular trajectory in the Earth coordinate system is converted into the angle list aN of the target coordinate system by subtracting the deviation value p1. That is, p1 is subtracted from each angle in the angle list bN. The calculation formula is: aN = bN - p1. Quick data filtering step S160: Select data from appropriate angles based on the needs of data analysis and processing.
2. The method according to claim 1, characterized in that: In step S120, The known angle a1 is the angle with the center of the target 1 as the coordinate system. The size of this angle can be arbitrarily selected. The UAV 2 can measure and record latitude and longitude information jw2 at any position in the direction of the known angle a1.
3. The method according to claim 1, characterized in that: In step S150, Perform a modulo operation on the converted angle aN to convert aN into data between 0 and 360 degrees.
4. The method according to claim 1, characterized in that: Step S160 specifically involves: All the latitude and longitude information of the circular trajectory SAR echo data is converted into 0-360 data centered on the target. Users can select a segment or multiple segments of the data for processing according to their data analysis and processing needs.
5. The method according to claim 2, characterized in that: The known angle is any known angle between 0 and 360 degrees.
6. The method according to claim 1, characterized in that: In the deviation value calculation step S130 Angle b1 is calculated using formula (1) through the position s1 of the center point c1 to be measured and the known angle a1: Where x is the angle to be calculated, w1 is the latitude of jw1, w2 is the latitude of jw2, j1 is the longitude of jw1, and j2 is the longitude of jw2.
7. The method according to claim 6, characterized in that: In circular trajectory SAR test step S140 The conversion method for the angle list bN is as follows: calculate the latitude and longitude of each point in jwN and the latitude and longitude of the target origin using formula (1), and the conversion results of all points are finally composed of the list bN.
8. The method according to claim 6, characterized in that: The drone can be a fixed-wing drone or a multi-rotor drone, and supports real-time latitude and longitude recording function; The real-time latitude and longitude recording function is as follows: during the test, the UAV can directly transmit the real-time latitude and longitude to the test radar, and record the latitude and longitude information synchronously through the test radar, or the UAV can generate a latitude and longitude information with a synchronization tag with the echo data in real time. The SAR echo data is the echo data generated by arbitrary synthetic aperture radar testing, and the target to be tested is any identifiable target on land or sea.
9. The method according to claim 8, characterized in that: The synchronous recording of latitude and longitude information means that for each echo data generated by the test, the latitude and longitude information at the time the echo data was generated can be found.
10. The method according to claim 9, characterized in that: When the real-time performance of latitude and longitude information does not meet the frequency of the test data, the latitude and longitude information of the data is obtained by linear interpolation.