Metal ball anti-swing method for metal ball calibration of meteorological radar

Abstract

The invention discloses a metal ball anti-swing method for metal ball calibration of a meteorological radar, and relates to the field of meteorological radars, comprising the following steps: S1, acquiring related information of a metal ball, a flying position and a radar; s2, determining a second rope length between the metal ball and the damping object according to the first rope length and the radar; s3, the mass of a damping object is determined according to the mass of the metal ball, and the shape of the damping object is determined; s4, the two ends of a connecting rope with the second rope length are connected with the metal ball and the damping object correspondingly; s5, the unmanned aerial vehicle is released at the releasing position, and at the beginning of releasing, the overall shaking amplitude of the metal ball and the damping object is reduced; according to the method, the influence of environmental wind and unmanned aerial vehicle movement on the stability of the metal ball is reduced to the greatest extent, the swing amplitude of the metal ball in the air is reduced, the time spent on aligning the antenna to the metal ball is shortened, and the accuracy of a calibration result is improved.

Description

Technical Field

[0001] The present invention relates to the field of weather radar, and in particular to a metal ball sway elimination method for metal ball calibration of weather radar. Background Art

[0002] Weather radar sphere calibration is a high-precision radar calibration method. A metal sphere of known size and electromagnetic properties is suspended as a standard reflector. The radar illuminates the sphere to simulate the radar's backscattered echo from meteorological particles such as clouds and rain, allowing for quantitative calibration of key radar system parameters (such as reflectivity factor and differential reflectivity). Traditional sphere calibration involves suspending the sphere from a drone using a tether to a specific location. Due to ambient wind and the drag of the drone during flight, the sphere experiences significant mid-air oscillation, requiring significant time to align the antenna with the sphere, compressing radar testing time within the limited flight time available for drone flight. This significant oscillation can also cause the sphere to move away from the antenna beam center, increasing calibration errors and impacting accuracy. To minimize the negative impact of sphere oscillation, traditional sphere calibration is typically performed in calm or low-wind conditions. However, this method has limited effectiveness and cannot eliminate the oscillation caused by the drone's drag during flight. Therefore, how to reduce the impact of environmental wind, reduce the swing amplitude of the metal ball, make the metal ball reach a stable state faster, and improve the accuracy of the calibration results are issues that need to be considered at present. Summary of the Invention

[0003] The purpose of the present invention is to design a metal ball sway elimination method for metal ball calibration of weather radar in order to solve the above problems.

[0004] The present invention achieves the above-mentioned purpose through the following technical solutions: The metal ball sway elimination method for weather radar metal ball calibration includes: S1. Obtain relevant information about the metal ball, its release location, and its radar. The relevant information includes the mass of the metal ball and the length L1 of the first rope between the metal ball and the drone. S2, determining a second rope length L2 between the metal ball and the damping object based on the first rope length and the radar; S3. Determine the mass of the damper according to the mass of the metal ball, and determine the shape of the damper; S4. Connect the ends of the second-long connecting rope to the metal ball and the damping object, respectively. The connecting rope and the metal ball are fixed at the intersection of the straight line formed by the connecting rope fixing point between the metal ball and the drone and the center of mass of the metal ball, extending to the surface of the metal ball. S5. Release the drone from the release position and, at the beginning of the release, reduce the overall shaking of the metal ball and damping material.

[0005] The beneficial effects of the present invention are: the method is effective and easy to implement, greatly reducing the impact of environmental wind and drone movement on the stability of the metal ball, reducing the swing amplitude of the metal ball in the air, shortening the time spent on aligning the antenna with the metal ball, and improving the accuracy of the calibration results. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 The figure is a schematic diagram of the metal ball sway elimination method for metal ball calibration of weather radar according to the present invention. DETAILED DESCRIPTION

[0007] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

[0008] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0009] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0010] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0011] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0012] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, terms such as "disposed" and "connected" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also mean internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0013] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0014] The metal ball sway elimination method for weather radar metal ball calibration includes: S1. Obtain information about the metal ball, its release location, and its radar. The information includes the mass of the metal ball and the length L1 of the first rope between the metal ball and the drone.

[0015] S2, determining a second rope length L2 between the metal ball and the damping object based on the first rope length and the radar; specifically comprising: S21. Determine the horizontal distance L3 between the launch position and the radar; S22. Calculate the scanning range B of the radar antenna at the azimuth position, expressed as: , where αradar is the elevation angle of the antenna and θ is the antenna beam width; S23, determining a first rope length L1 according to the scanning range B, specifically: the first rope length L1 is greater than 0.5 times the scanning width B; S24. Determine the second rope length L2 based on the first rope length L1. Specifically, the second rope length L2 is equal to the first rope length L1.

[0016] S3. Determine the mass of the damper according to the mass of the metal ball, and determine the shape of the damper; specifically: the mass of the damper is 0.1 times the mass of the metal ball, and the shape of the damper is spherical or cylindrical.

[0017] S4. Connect the two ends of the second-long connecting rope to the metal ball and the damping object respectively. The fixed position between the connecting rope and the metal ball is selected from the intersection of the straight line formed by the fixing point of the connecting rope between the metal ball and the drone and the center of mass of the metal ball and the surface of the metal ball.

[0018] S5. Release the drone from the release position and, at the beginning of the release, reduce the overall shaking of the metal ball and damping material.

[0019] like Figure 1As shown, regarding the connecting rope: one end of the connecting rope is connected to the damping object, and the other end is fixed to the bottom of the metal ball, forming a new simple pendulum system together with the damping object. The connecting rope is made of nylon wire, which is a high-strength, good-toughness and light-weight wire, so that its mass in the entire simple pendulum system can be ignored. In order to achieve a more effective anti-swing effect, the first rope length L1 between the metal ball and the drone and the second rope length L2 between the damping object and the metal ball must meet the frequency tuning conditions, and the natural frequency of the damping object, the connecting rope and the main pendulum must be consistent. The natural frequency of the simple pendulum , g is the acceleration due to gravity, and L is the pendulum length. To meet the frequency tuning condition, L2=L1, that is, the two ropes are of equal length.

[0020] The length of the rope between the metal ball and the drone, L2, is used to determine the length of the rope between the damper and the metal ball. To meet far-field requirements during calibration, the metal ball is released at a horizontal distance of L3 from the radar. The sweep width B at this distance is calculated (the metal ball position is searched within a range of three times the beam width during calibration). Sweep width B is expressed as: ; Where α is the antenna's elevation angle (°), and θ is the antenna beamwidth (°). The metal ball is suspended in the center of the antenna beam. To prevent the drone's echo from affecting the calibration results, the drone must be outside the sweep width. Therefore, the rope length L1 must be greater than 0.5 times the sweep width B. After determining the rope length L1, the rope length L2 is set to be equal to L1 to meet the resonance condition. Because the radar antenna has an elevation angle α with the horizontal ground, at horizontal distance L3, if the rope length L1 ensures that the drone is outside the sweep range, the rope length L2 also ensures that the damping object is outside the sweep range, preventing interference with the echo and causing error in the results.

[0021] Damping material selection: The vibration energy of the metal ball is absorbed by the movement of the damping material. When the mass ratio μ of the damping material to the metal ball is 0.1, it can have the characteristics of light load and strong anti-sway effect. That is, the mass of the damping material is Take the mass of the metal ball One tenth of the weight of a metal ball Get the mass of the damping material The shape of the damper is selected to be spherical, cylindrical or other shapes with low wind resistance to reduce the impact of ambient wind on the tuned mass damper itself.

[0022] Connect the damping element and the connecting rope: Use the selected connecting rope to connect one end to the damping element and secure the other end to the bottom of the metal ball. The securing position is the intersection of the straight line formed by the connecting rope's attachment point to the metal ball and the center of mass of the metal ball, extending to the intersection of the metal ball's surface.

[0023] Release the drone: Release the metal ball and before the metal ball and the damping object fly out of reach, manually reduce the overall swing of the system to put the entire system in a relatively stable state to speed up the metal ball's swing elimination process.

[0024] Use a counterweight with uniform mass distribution as a damper. The damper absorbs the vibration energy of the main structure through movement, thus achieving a vibration reduction effect. The relationship with mass ratio μ is: 、 ; in, is the mass of the damping block (kg), is the mass of the metal ball (kg). The mass ratio μ is generally set to 0.1, meaning the damping mass is one-tenth the mass of the metal ball. At this point, the vibration reduction effect can reach 49%. Further increasing the mass of the damping block will only slightly improve the vibration reduction effect, and higher mass can induce geometric nonlinear effects. To prevent the damping mass from being significantly disturbed by the ambient wind, the damping mass should be designed with minimal wind resistance.

[0025] This method is effective and easy to implement. It greatly reduces the impact of environmental wind and drone drag on the stability of the metal ball, reduces the swing amplitude of the metal ball in the air, reduces the time spent on antenna alignment, and improves the accuracy of the calibration results.

[0026] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A metal ball sway elimination method for metal ball calibration of weather radar, characterized in that: include: S1. Obtain relevant information about the metal ball, its release location, and its radar. The relevant information includes the mass of the metal ball and the length L1 of the first rope between the metal ball and the drone. S2, determining a second rope length L2 between the metal ball and the damping object based on the first rope length and the radar; S3. Determine the mass of the damper according to the mass of the metal ball, and determine the shape of the damper; S4. Connect the ends of the second-long connecting rope to the metal ball and the damping object, respectively. The connecting rope and the metal ball are fixed at the intersection of the straight line formed by the connecting rope fixing point between the metal ball and the drone and the center of mass of the metal ball, extending to the surface of the metal ball. S5. Release the drone from the release position and, at the beginning of the release, reduce the overall shaking amplitude of the metal ball and the damping object.

2. The metal ball sway elimination method for weather radar metal ball calibration according to claim 1, characterized in that: Included in S2: S21. Determine the horizontal distance L3 between the launch position and the radar; S22. Calculate the scanning range B of the radar antenna at the azimuth position; S23, determining the first rope length L1 according to the scanning range B; S24. Determine the second rope length L2 based on the first rope length L1.

3. The metal ball sway elimination method for weather radar metal ball calibration according to claim 2, characterized in that: In S22, the scanning range B is expressed as: , where α is the elevation angle of the antenna and θ is the antenna beamwidth.

4. The metal ball sway elimination method for weather radar metal ball calibration according to claim 2, characterized in that: In S23 , the first rope length L1 is greater than 0.5 times the scanning width B.

5. The metal ball sway elimination method for weather radar metal ball calibration according to claim 2, characterized in that: In S24, the second rope length L2 is equal to the first rope length L1.

6. The metal ball sway elimination method for metal ball calibration of weather radar according to claim 1, characterized in that: In S3, the mass of the damper is 0.1 times the mass of the metal ball, and the shape of the damper is spherical or cylindrical.

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