Mobile thunder and lightning three-dimensional positioning system and method

Abstract

The invention provides a mobile thunder and lightning three-dimensional positioning system. The mobile thunder and lightning three-dimensional positioning system is composed of a vehicle-mounted ground master station, a plurality of airborne aerial substations and a plurality of maneuvering aerial substations. The vehicle-mounted ground master station and the airborne aerial substation are provided with lightning signal acquisition devices, the vehicle-mounted ground master station adopts an automobile as a ground mobile carrier, and the airborne aerial substation and the maneuvering aerial substation adopt unmanned rotorcrafts as aerial mobile carriers. The airborne aerial substations are arranged in a staggered manner, and the airborne aerial substations and the vehicle-mounted ground master station form a space-ground integrated three-dimensional mobile thunder and lightning detection network with a ground layer, a low-altitude layer and a hollow layer. The layout form of the mobile vehicle-mounted ground master station and the airborne aerial substation can be changed at any time, and the maneuverability is high. The airborne aerial substation is provided with a wireless signal transmitting device, a lightning signal is transmitted after being processed and modulated, the lightning signal is transmitted back to the vehicle-mounted ground master station in a wireless mode, and the vehicle-mounted ground master station solves the three-dimensional position of a lightning radiation source through a lightning positioning algorithm.

Description

Technical Field

[0001] The invention relates to the fields of meteorology, atmospheric electricity and space science and technology, and in particular to a three-dimensional lightning positioning system and method. Background Art

[0002] Lightning is one of the natural phenomena in atmospheric electromagnetic activities. Lightning disasters seriously threaten human life and property safety. Since the time and space of lightning occurrence are highly random, lightning strikes are extremely harmful and cause disasters quickly, which brings many difficulties to its research, prediction and prevention. Lightning location has important scientific significance for detecting the charge structure, charge density distribution and its evolution with the development of thunderstorm process in thunderstorm clouds, and for revealing the physical mechanism of lightning occurrence and development process. There are many lightning location methods in the prior art, such as: the time difference of arrival method (TDOA) is one of the commonly used lightning location technologies. Generally, the arrival time difference of 4 or 5 measuring stations is used. The redundant information data fusion can improve the positioning accuracy, solve a three-dimensional positioning estimate of lightning, and then optimize the fitting.

[0003] The lightning location method of the prior art arranges multiple stations on the ground at a distance of several kilometers or even larger to form a lightning detection network. Although there is a certain height difference between the ground of each station, the height difference is very small compared to the distance between the stations. The station layout of the lightning detection network can be regarded as a plane. The incident angle of the lightning radiation source far away from the station is small, and the height error in the lightning location result is relatively large. When the detection station set on the ground receives lightning signals, the propagation error of the radio wave on the complex terrain and the electromagnetic noise generated by the electrical equipment on the ground will affect the lightning location accuracy. Placing one or several stations on high-rise buildings and mountains can appropriately solve the above problems, but high-rise buildings and mountains may block the lightning radiation source and affect lightning detection. Therefore, in the study of lightning detection and location, the lightning detection network is generally selected in relatively open areas. Temporary iron towers are also built to set the antennas of individual stations on the towers, but the height of the tower is limited. Generally, the tower height is 30~50m. If it is higher, the construction cost and difficulty will increase greatly. This method is not effective. The existing lightning detection network is fixed and can only passively wait for the right lightning, and cannot adapt to the changing thunderstorm weather. Therefore, it is necessary to develop a new mobile three-dimensional lightning positioning network to solve the defects of the existing technology. Summary of the invention

[0004] The purpose of the present invention is to provide a mobile three-dimensional lightning positioning system, which is composed of a vehicle-mounted ground master station, several airborne aerial substations, and several mobile aerial substations. The vehicle-mounted ground master station, the airborne aerial substation, and the mobile aerial substation are equipped with a lightning signal acquisition device. The vehicle-mounted ground master station uses a car as a ground mobile vehicle, and the airborne aerial substation and the mobile aerial substation use a rotor drone as an air mobile vehicle. The airborne aerial substations are arranged at different heights, and form a three-dimensional mobile lightning detection network integrating the ground layer, the low-altitude layer, and the hollow layer with the vehicle-mounted ground master station. The airborne aerial substation is equipped with a wireless signal transmitting device, and the lightning signal is transmitted after being processed and modulated. The vehicle-mounted ground master station is equipped with a wireless signal receiving device, and the lightning signal is transmitted back to the vehicle-mounted ground master station by wireless means. The vehicle-mounted ground master station uses a lightning positioning algorithm to solve the three-dimensional position of the lightning radiation source.

[0005] The technical solution adopted by the present invention is: to provide a mobile lightning three-dimensional positioning system, which is composed of a vehicle-mounted ground main station 100, a plurality of airborne aerial substations 200, and a plurality of mobile aerial substations 300. The vehicle-mounted ground main station 100, the airborne aerial substation 200, and the mobile aerial substation 300 are equipped with a lightning signal collection device 400. The vehicle-mounted ground main station 100 uses a car as a ground mobile vehicle, and the airborne aerial substation 200 and the mobile aerial substation 300 use a rotor drone as an aerial mobile vehicle.

[0006] The vehicle-mounted ground master station 100 is equipped with a GNSS global satellite navigation receiving device 101. The airborne aerial substation 200 and the mobile aerial substation 300 obtain GNSS global satellite navigation signals through the built-in GNSS global satellite navigation system of the unmanned aerial vehicle. The GNSS global satellite navigation signals are used for lightning signal timing synchronization, and the precise three-dimensional coordinates of the vehicle-mounted ground master station 100 and the airborne aerial substation 200 are obtained through real-time dynamic carrier phase difference (RTK), which can mark the timestamp of the collected lightning signals and record the coordinates of the measuring station at the moment of lightning occurrence.

[0007] The lightning signal acquisition device 400 adopts an FPGA lightning signal high-speed data acquisition system, which is mainly composed of an FPGA logic gate circuit and an embedded ARM processor.

[0008] The number of the airborne aerial substations 200 is at least 4 but not limited to 4, and the positioning data and redundant data are obtained to remove the fuzzy solution. The airborne aerial substations 200 are arranged at different heights, and form a three-dimensional mobile lightning detection network integrating the ground layer, the low-altitude layer, and the hollow layer with the vehicle-mounted ground main station 100. According to the location where the lightning occurs, by changing the layout of the mobile vehicle-mounted ground main station 100 and the airborne aerial substations 200, the spatial form between the lightning detection network and the lightning can be adjusted to form the best spatial triangular geometric position relationship with the lightning occurrence location, which is conducive to improving the lightning positioning accuracy.

[0009] The mobile aerial substation 300 has the same configuration as the airborne aerial substation 200, at least one but not limited to one, and is used to replace the working airborne aerial substation 200 to achieve continuous operation of the airborne aerial substation 200. The replaced airborne aerial substation 200 can be used as a new mobile aerial substation 300 after the battery is replaced.

[0010] The airborne aerial substation 200 is equipped with a wireless signal transmitting device 201. The lightning signal collected by the lightning signal collecting device 400 is modulated after processing. Each airborne aerial substation 200 transmits at a different frequency. The vehicle-mounted ground main station 100 is equipped with a wireless signal receiving device 102. The lightning signal collected by the airborne aerial substation 200 is transmitted back to the vehicle-mounted ground main station 100 by wireless means. The signal received by the wireless signal receiving device 102 is demodulated by the FSK demodulation module 103 for signals of different frequencies and stored in the data storage device 104 of the vehicle-mounted ground main station 100.

[0011] The vehicle-mounted ground master station 100 is equipped with a data processing and computing unit 105. Through the lightning signals collected by the vehicle-mounted ground master station 100 and the lightning signals returned by the airborne aerial substation 200, the data processing and computing unit 105 uses a lightning positioning algorithm to solve the three-dimensional position of the lightning radiation source.

[0012] The lightning signal acquisition device 400 adopts an FPGA lightning signal high-speed data acquisition system, which is mainly composed of an FPGA logic gate circuit and an embedded ARM processor. The FPGA logic gate circuit realizes analog-to-digital conversion control, lightning data acquisition, timestamp acquisition, pre-trigger and trigger control, peak acquisition, and output control. The FPGA logic gate circuit filters the collected signal, oversamples, calculates the signal amplitude through Hilbert transform, and triggers the peak value extraction function. The processed data is temporarily stored in the DDR data storage unit using DMA. After the data is processed by ARM, the corresponding data is extracted from the cache of the DDR data storage unit for local storage. The airborne aerial substation 200 will transmit the data back to the vehicle-mounted ground main station 100 through wireless after modulation.

[0013] The vehicle-mounted ground master station 100 is equipped with a drone cluster control system 106, which can automatically control the deployment of the airborne aerial substation 200 according to the set position, and can automatically control the mobile aerial substation 300 to replace the airborne aerial substation 200 according to the set drone remaining power.

[0014] The lightning signal acquisition device 400 comprises a high-speed A / D conversion module 1, a GNSS signal processing unit 2, a data processing unit 3, a DDR data storage unit 4, and an ARM processing unit 5. The high-speed A / D conversion module 1 converts the analog signal output by the lightning detection sensor into a digital signal; the GNSS signal processing unit 2 outputs a high-precision clock frequency as the sampling reference clock of the high-speed A / D conversion module 1 to ensure the accuracy of the signal conversion time, and the output high-precision full-second clock signal 1PPS and NMEA0183 data with time information cooperate with the sampling reference clock to mark the timestamp for the collected lightning signal; the GNSS signal processing unit 2 outputs the RTK coordinates, and the coordinate acquisition module marks the timestamp for the coordinates and outputs the coordinates marked with the timestamp; the FPGA logic gate circuit constitutes the data processing unit 3 through programming to realize analog-to-digital conversion control, lightning detection data acquisition, timestamp acquisition, coordinate calibration, pre-trigger and trigger control, peak acquisition, and output control. The FPGA logic gate circuit filters the signal marked with the timestamp, oversamples, calculates the signal amplitude through Hilbert transform, and extracts the trigger judgment peak value. The lightning signal and the coordinates marked with the timestamp are combined and output, and the processed data are temporarily stored in the DDR data storage unit 4 using DMA, and the ARM processing unit 5 is notified to process the data. The ARM processing unit 5 embedded operating system extracts the peak data and the corresponding time information and coordinates after receiving the notification of data collection. The lightning signal collection device 400 of the vehicle-mounted ground master station 100 extracts the corresponding data and stores it in the data storage 104. The lightning signal collection device 400 of the airborne aerial substation 200 extracts the corresponding data and stores it in the file storage unit 202, and sends it wirelessly to the vehicle-mounted ground master station 100 through the wireless signal transmitting device 201.

[0015] The present invention provides a mobile three-dimensional lightning positioning method, comprising the following steps: S1. A lightning detection network is deployed in the lightning location area, and the drone cluster control system 106 of the vehicle-mounted ground master station 100 controls the drones of the airborne aerial substation 200 to be in position according to the set plane position and elevation; S2, the vehicle-mounted ground master station 100 and the airborne aerial substation 200 collect lightning signals; S3, setting the low-power return power threshold of the airborne aerial substation 200, when the power of any airborne aerial substation 200 is lower than the return power threshold, the mobile aerial substation 300 starts to replace the airborne aerial substation 200; S4. The data processing and computing unit 105 of the vehicle-mounted ground master station 100 obtains several lightning arrival locations through spatial analysis through the time difference (TDOA) of the lightning signal arriving at each measuring station, obtains an initial solution using the weighted least squares method, and then uses the obtained initial solution and the constraint variables to perform a second weighted least squares method estimation to finally obtain an improved position estimate.

[0016] In the step S1, the vehicle-mounted ground master station 100 and the airborne aerial substation 200 are arranged to avoid mountains and high-rise buildings, the distance between the airborne aerial substations 200 is 5-10 km, the low-altitude layer height is 300-1000 m, and the middle-altitude layer height is 1000-2000 m. During a continuous lightning event, the positions of the vehicle-mounted ground master station 100 and the airborne aerial substation 200 are fixed. The vehicle-mounted ground master station 100 can move the vehicle-mounted ground master station 100 and control the airborne aerial substation 200 to change the spatial layout according to the direction of the lightning, thereby forming the best spatial triangular geometric position relationship with the lightning occurrence position, thereby improving the accuracy of lightning positioning solution.

[0017] In the step S3, the return power threshold is set to 40% to 50% of the full power of the power supply. The drone cluster control system 106 controls the mobile aerial substation 300 to fly to the drone airspace below the return power threshold, replaces the airborne aerial substation 200, and the replaced airborne aerial substation 200 replaces the battery as a new mobile aerial substation 300, replaces the airborne aerial substation 200 with the lowest voltage, and gradually replaces all the airborne aerial substations 200. After completing a round of replacement, the mobile aerial substation 300 waits for the next drone power supply to be lower than the return power threshold, and then executes the replacement of the airborne aerial substation 200.

[0018] The step S4, the time difference of arrival (TDOA) positioning, is based on the known spatial position of the master station S0 ( x 0 , y 0 ,z 0) and substation S i The spatial position of x i ,y i ,z i ), with the spatial coordinates of the lightning radiation source P ( x, y, z ) is a variable, and the electromagnetic waves radiated by the lightning radiation source reach each substation S i The time difference to the master station S0 is Δ τ i , establish the system of equations and solve them: , Where: Δ τ i =( τ 0 - τ i ), c is the propagation speed of electromagnetic waves, τ 0 is the time it takes for the electromagnetic wave radiated by the lightning radiation source to reach the main station, τ i is the time it takes for the electromagnetic wave radiated by the lightning radiation source to reach the substation, i =1,2,3…… n , n is the number of substations. The initial solution of the equation group is obtained, and the weighted least squares method is used to estimate the lightning position using the initial solution and constraint variables.

[0019] The beneficial effects of the present invention are: based on weather forecasts and thunderstorm cloud electric field detection, the detection instrument can be transported to the area where lightning is about to occur by using ground vehicles. The drone cluster control system of the vehicle-mounted ground main station controls the drones of the airborne aerial substation to be in place according to the set plane position and elevation, and the system has strong mobility. The layout of the mobile vehicle-mounted ground main station and the airborne aerial substation can be changed, and the spatial form between the lightning detection network and the lightning can be adjusted, which is conducive to the lightning position solution. The system uses RTK real-time dynamic carrier phase difference to determine the station position, and the station position accuracy can reach the centimeter level, greatly improving the accuracy of lightning positioning. The mobile aerial substation is used to rotate and replace the airborne aerial substation to achieve continuous operation of the airborne aerial substation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the lightning location system of the present invention; Figure 2 It is the working principle diagram of the present invention; Figure 3 This is the lightning signal collection principle diagram of the vehicle-mounted ground master station; Figure 4 This is the schematic diagram of lightning signal collection for airborne aerial substation.

[0021] In the figure: 100-vehicle-mounted ground main station, 200-aircraft-mounted aerial substation, 300-dynamic aerial substation, 400-lightning signal acquisition device, 101-GNSS global satellite navigation receiving device, 102-wireless signal receiving device, 103-FSK demodulation module, 104-data storage device, 105-data processing and calculation unit, 106-UAV cluster control system, 201-wireless signal transmitting device, 202-file storage unit, 1-high-speed A / D conversion module, 2-GNSS signal processing unit, 3-data processing unit, 4-DDR data storage unit, 5-ARM processing unit. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to better understand the present invention, Figure 1 to Figure 4 The present invention is further described, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0023] The mobile lightning three-dimensional positioning system of the present invention is composed of a vehicle-mounted ground master station 100, a plurality of airborne aerial substations 200, and a plurality of mobile aerial substations 300. The schematic diagram of the lightning positioning system of the present invention is shown in FIG. Figure 1 , Figure 1 The number of the four airborne substations 200 is for illustration only. The vehicle-mounted ground master station 100, the airborne substation 200, and the mobile airborne substation 300 are equipped with a lightning signal acquisition device 400. The airborne substation 200 is equipped with a wireless signal transmitting device 201. The lightning signal collected by the lightning signal acquisition device 400 is modulated after processing. Each airborne substation 200 transmits at a different frequency. The vehicle-mounted ground master station 100 is equipped with a wireless signal receiving device 102. The lightning signal collected by the airborne substation 200 is wirelessly sent to the vehicle-mounted ground master station 100 through the wireless signal transmitting device 201. The signal received by the wireless signal receiving device 102 is demodulated by the FSK demodulation module 103 to demodulate the signal of different frequencies and stored in the data storage device 104 of the vehicle-mounted ground master station 100. The vehicle-mounted ground master station 100 is equipped with a data processing and computing unit 105. Through the lightning signals collected by the vehicle-mounted ground master station 100 and the lightning signals returned by the airborne aerial substation 200, the data processing and computing unit 105 uses a lightning positioning algorithm to solve the three-dimensional position of the lightning radiation source. The working principle diagram of the present invention is shown in Figure 2 .

[0024] The vehicle-mounted ground master station 100 uses a car as a ground mobile vehicle, and the airborne aerial substation 200 and the mobile aerial substation 300 use a rotor drone as an aerial mobile vehicle. The vehicle-mounted ground master station 100 is equipped with a drone cluster control system 106, which can automatically control the deployment of the airborne aerial substation 200 according to the set position, and can automatically control the mobile aerial substation 300 to replace the airborne aerial substation 200 according to the set remaining power of the drone. The control distance of the rotor drone varies depending on the type and application scenario. Consumer-grade drones usually use handheld remote controls, and the remote control distance is generally around 1 kilometer; industrial-grade drones are equipped with measurement and control equipment, and the effective control distance is generally from a few kilometers to tens of kilometers. The remote control distance of high-end drones can reach 100 kilometers. Generally, consumer-grade rotor drones are quad-rotors, and the flight altitude is limited to no more than 500m. In addition to quad-rotors, industrial-grade rotor drones also have six-rotors and eight-rotors, and the flight altitude can reach nearly 2000m. The mobile lightning three-dimensional positioning system of the present invention uses a vehicle-mounted ground main station 100 to transport the airborne aerial substation 200 and the mobile aerial substation 300 to a predetermined area, and a transport vehicle may also be configured separately. The station spacing of the lightning detection network is generally not more than 20 kilometers, and an industrial-grade drone with a wingspan of 1 to 2 meters can be used. The endurance of a rotary-wing drone mainly depends on the battery. The endurance of a general drone is 0.5 to 1 hour, and the battery can be increased to 2 hours. However, a lightning process often lasts for several hours. In order to ensure the continuous operation of the airborne aerial substation 200, the present invention adopts a method of replacing the airborne aerial substation 200 with the mobile aerial substation 300. The configuration of the mobile aerial substation 300 and the airborne aerial substation 200 are the same. When the power of the drone of a certain airborne substation 200 is lower than the return power threshold, the mobile airborne substation 300 flies to the airspace of the airborne airborne substation 200 to be replaced, switches the lightning detection device in the interval of lightning, and realizes the continuous operation of the airborne airborne substation 200. The return position of the replaced airborne airborne substation 200 is determined by the control system of the vehicle-mounted ground main station 100, and lands next to the vehicle-mounted ground main station 100 or the transport vehicle. After the battery is replaced, it serves as a new mobile airborne substation 300. The mobile airborne substation 300 of the present invention is at least one but not limited to one, which is determined according to the number of airborne airborne substations 200. Generally, one mobile airborne substation 300 is configured for less than 5 airborne airborne substations 200, and two or more mobile airborne substations 300 can be configured for more than 5 airborne airborne substations 200.

[0025] Lightning location uses a system of one main station plus several substations. In order to obtain redundant data and remove fuzzy solutions, the number of substations must be at least four to solve the fuzzy solution. As the number of substations increases, the redundant positioning data increases, and the accuracy of the result obtained by the least squares method will also increase. The airborne substations 200 of the present invention are at least 4 but not limited to 4, which obtain positioning data and redundant data to remove fuzzy solutions. As the number of substations increases, the investment in establishing the system increases, so the number of substations is preferably 4 to 10. The airborne aerial substation 200 is arranged at a staggered height, and the vehicle-mounted ground main station 100 is preferably arranged in the middle of the lightning detection network. The airborne aerial substation 200 is slightly lower near the lightning radiation source P, and slightly higher away from the lightning radiation source P. The airborne aerial substation 200 and the vehicle-mounted ground main station 100 form a three-dimensional mobile lightning detection network integrating the ground layer, the low-altitude layer, and the hollow layer. According to the location where the lightning occurs, the layout form is changed by moving the vehicle-mounted ground main station 100 and the airborne aerial substation 200, and the spatial form between the lightning detection network and the lightning is adjusted to form the best spatial triangular geometric position relationship with the lightning occurrence location, which is conducive to improving the lightning positioning accuracy. When the present invention is actually implemented, in addition to the airborne aerial substation 200, 1 to 2 vehicle-mounted mobile substations can also be set, which can move farther and form a larger lightning detection network without being limited by the control distance and endurance of the drone. The vehicle-mounted mobile substation and the vehicle-mounted ground main station 100 are connected by a wide area network.

[0026] This system uses the global satellite positioning system GNSS timing to obtain a unified coordinate position and the absolute time of the lightning signal. The GNSS global satellite navigation system can use China's Beidou satellite navigation system BDS, or the US satellite navigation system GPS, the Russian satellite navigation system GLONASS, and the EU satellite navigation system GALILEO, preferably BDS or GPS. The vehicle-mounted ground master station 100 is equipped with a GNSS global satellite navigation receiving device 101, including a GNSS antenna and a GNSS signal receiver, see Figure 3 Schematic diagram of lightning signal collection of vehicle-mounted ground master station. Airborne substation 200 and mobile substation 300 obtain GNSS global satellite navigation signals through the built-in GNSS global satellite navigation system of the UAV, see Figure 4Schematic diagram of lightning signal collection at an airborne substation. The vehicle-mounted ground master station 100, the airborne substation 200 and the mobile airborne substation 300 should use the same global satellite positioning system. The GNSS global satellite navigation signal is used for lightning signal timing synchronization, and to obtain the precise three-dimensional coordinates of the vehicle-mounted ground master station 100 and the airborne substation 200 through real-time kinematic carrier phase differential (RTK), which can mark the timestamp of the collected lightning signal and record the coordinates of the measuring station at the moment of lightning. RTK (Real-time kinematic) real-time dynamic carrier phase differential technology is a differential method for real-time processing of carrier phase observations of two measuring stations. The carrier phase collected by the reference station is sent to the user receiver to calculate the difference coordinates. In this application, the vehicle-mounted ground master station 100 is used as the reference station, and the airborne substation 200 is used as the user receiver. The coordinates of each airborne substation 200 are respectively solved through the coordinates of the vehicle-mounted ground master station 100. The coordinates of the vehicle-mounted ground main station 100 are obtained through the GNSS global satellite navigation system. Although the accuracy is only at the meter level, which has met the lightning positioning accuracy requirements, the coordinate accuracy of the airborne aerial substation 200 relative to the vehicle-mounted ground main station 100 can reach the centimeter level through RTK solution, which can greatly improve the accuracy of lightning positioning solution.

[0027] The lightning signal acquisition device 400 of the present application adopts an FPGA lightning signal high-speed data acquisition system, which is mainly composed of an FPGA logic gate circuit and an embedded ARM processor. It is implemented by a combination of software and hardware, using FPGA as hardware and embedded processor as software, so that hardware and software are designed as an organic whole to achieve the best combination of hardware and software. FPGA is a chip whose internal structure can be changed by programming. Its full name is Field Programmable Gate Array, which is a field programmable gate array. It is a digital integrated circuit whose internal hardware resources include configurable basic logic units and configurable hardware connections. The internal structure of FPGA can be changed and configured by software means to achieve specific design functions. The design and development process of FPGA involves programming using hardware description language, and then compiling, synthesizing, and layout and routing through EDA tools, and finally converting it into a burnable file and loading it into the FPGA device, thereby changing its internal connections and completing the realization of the required functions. The FPGA logic gate circuit realizes analog-to-digital conversion control, lightning data acquisition, timestamp acquisition, pre-trigger and trigger control, peak acquisition, and output control. The FPGA logic gate circuit filters the collected signal, oversamples, calculates the signal amplitude through Hilbert transform, and extracts the trigger judgment peak value. The processed data is temporarily stored in the DDR data storage unit using DMA. After data processing, the lightning signal is output from the FPGA at a speed of 80MHZ 16-bit data with a data volume of 160MB / s. The maximum rate of writing data to the file storage unit through the FATFS file system is 1MB / s, and the file creation time must also be considered. Therefore, the lightning signal acquisition speed is much faster than the file writing speed. Using DDR as a cache can effectively solve this problem. The DDR data storage unit is an FPGA peripheral device, which is used to cache lightning data from the FPGA logic gate circuit to the ARM processing unit. The lightning waveform data, peak data, and time data output by the data processing unit are transmitted to the DDR data storage unit for temporary storage. Then all data are read from the DDR data storage unit and written to the file storage unit through the ARM processing unit to make up for the speed difference between lightning signal acquisition and file writing.

[0028] The lightning signal acquisition device 400 includes a high-speed A / D conversion module 1, a GNSS signal processing unit 2, a data processing unit 3, a DDR data storage unit 4, and an ARM processing unit 5. The high-speed A / D conversion module 1 converts the analog signal output by the lightning detection sensor into a digital signal. The GNSS signal processing unit 2 outputs a high-precision clock frequency as a sampling reference clock of the high-speed A / D conversion module 1 to ensure the accuracy of the signal conversion time. The output high-precision full-second clock signal 1PS and NMEA0183 data with time information are used in conjunction with the sampling reference clock to mark the timestamp for the collected lightning signal. The RTK coordinates output by the GNSS signal processing unit 2 are marked with a timestamp by the coordinate acquisition module, and the coordinates marked with the timestamp are output. The FPGA logic gate circuit is programmed to form a data processing unit 3, which realizes analog-to-digital conversion control, lightning detection data acquisition, timestamp acquisition, coordinate calibration, pre-trigger and trigger control, wave peak acquisition, and output control. The FPGA logic gate circuit filters the signal marked with the timestamp, oversamples, calculates the signal amplitude by Hilbert transform, extracts the trigger judgment peak value, and outputs the lightning signal and the coordinates of the marked timestamp. The processed data is temporarily stored in the DDR data storage unit 4 using DMA, and the ARM processing unit 5 is notified to process the data. The ARM processing unit 5 embedded operating system extracts the corresponding data storage from the cache of the DDR data storage unit 4 after receiving the notification of data collection. The extracted data includes peak data and corresponding time information and coordinates.

[0029] The lightning signal acquisition device 400 of the vehicle-mounted ground master station 100 of the present invention is basically the same as the lightning signal acquisition device 400 of the airborne aerial substation 200. The difference is that the lightning signal acquisition device 400 of the vehicle-mounted ground master station 100 extracts the corresponding data from the DDR data storage unit cache through the file storage module after the data is processed by ARM, and directly outputs and stores it in the data storage device 104 of the vehicle-mounted ground master station 100. Figure 3 The lightning signal acquisition device 400 of the airborne aerial substation 200 processes the data through ARM, extracts the corresponding data from the DDR data storage unit cache, and then transmits the data to the vehicle-mounted ground master station 100 through the wireless signal transmitting device 201 after the data is modulated by the data modulation module through the file storage module. At the same time, the extracted data is stored in the file storage unit 202 through the file storage module. Figure 4 The file storage unit 202 is the local storage of the airborne substation 200, and can use an SD card or a solid state hard disk as a storage medium. The data stored in the file storage unit 202 is used as a backup of the wireless transmission data. After the airborne substation 200 returns, the substation number is determined according to the marked timestamp and coordinates, and the data is copied to the data storage 104 of the vehicle-mounted ground master station 100.

[0030] The mobile three-dimensional lightning positioning method of the present invention comprises the following steps: Step 1: Establish a lightning detection network. According to weather forecasts and thunderstorm cloud electric field detection, the area where lightning will occur is estimated, and the vehicle-mounted ground master station 100 is used to transport the airborne aerial substation 200 and the mobile aerial substation 300 to the predetermined area. Alternatively, a transport vehicle can be configured for transportation. The vehicle-mounted ground master station 100 or the transport vehicle is equipped with a small generator and a backup battery and charging device for the drone. A lightning detection network is laid out in the lightning positioning area, and the drone cluster control system 106 of the vehicle-mounted ground master station 100 controls the drones of the airborne aerial substation 200 to be in place according to the set plane position and elevation. The vehicle-mounted ground master station 100 and the airborne aerial substation 200 should be arranged away from mountains and high-rise buildings. The distance between the airborne aerial substations 200 is 5~10km, the low-altitude layer height is 300~1000m, and the middle-altitude layer height is 1000~2000m. During a continuous lightning event, the positions of the vehicle-mounted ground master station 100 and the airborne aerial substation 200 are fixed. The vehicle-mounted ground master station 100 can move the vehicle-mounted ground master station 100 and control the airborne aerial substation 200 to change the spatial layout according to the direction of the lightning, thereby forming the best spatial triangular geometric position relationship with the lightning location and improving the accuracy of lightning location solution.

[0031] Step 2: Lightning signal collection: The vehicle-mounted ground master station 100 and the airborne aerial substation 200 collect lightning signals, and the lightning signals collected by the vehicle-mounted ground master station 100 are stored in the local data storage 104 , and the lightning signals collected by the airborne aerial substation 200 are transmitted to the vehicle-mounted ground master station 100 by wireless transmission and stored in the data storage 104 of the vehicle-mounted ground master station 100 .

[0032] Step 3: Replacement of the airborne aerial substation 200. The drone cluster control system 106 of the vehicle-mounted ground master station 100 sets the drone low-power return-to-home power threshold of the airborne aerial substation 200. The return-to-home power threshold is set to 40% to 50% of the full power of the power supply. When the drone power of any airborne aerial substation 200 is lower than the return-to-home power threshold, the mobile aerial substation 300 starts to replace the airborne aerial substation 200. The drone cluster control system 106 controls the mobile aerial substation 300 to fly to the drone airspace below the return-to-home threshold and replace the airborne aerial substation 200. The replaced airborne aerial substation 200 replaces the battery as a new mobile aerial substation 300, and replaces the airborne aerial substation 200 with the lowest voltage. All airborne aerial substations 200 are gradually replaced. After completing a round of replacement, the mobile aerial substation 300 waits for the next drone power to be lower than the return-to-home power threshold, and then performs the replacement of the airborne aerial substation 200.

[0033] Step 4: Lightning location calculation. The data processing and calculation unit 105 of the vehicle-mounted ground master station 100 uses the time difference (TDOA) of the lightning signal arriving at each measuring station, and according to the known spatial position of the master station S0 ( x 0 ,y 0 ,z 0) and substation S i The spatial position of x i ,y i ,z i ), with the spatial coordinates of the lightning radiation source P ( x, y, z ) is a variable, the electromagnetic waves radiated by the lightning radiation source P reach each substation S i The time difference to the master station S0 is Δ τ i , establish the system of equations and solve them: , Where: Δ τ i =( τ 0 - τ i ), c is the propagation speed of electromagnetic waves, τ 0 is the time it takes for the electromagnetic wave radiated by the lightning radiation source to reach the main station, τ i is the time it takes for the electromagnetic wave radiated by the lightning radiation source to reach the substation, i =1,2,3…… n , n The weighted least square method is used to solve the equations to obtain the initial solution, and several lightning arrival locations are obtained by spatial analysis. The initial solution and constraint variables are used to perform the second weighted least square method estimation, and finally the improved location estimate is obtained.

[0034] The implementation of the present invention can cooperate with drone manufacturers to obtain the time and coordinate information of the drone's built-in GNSS global satellite navigation system, and even use the drone's image return system to transmit lightning signals. When implementing lightning positioning, it should be reported to the relevant departments and strictly abide by relevant laws and regulations to ensure flight safety.

[0035] The description and drawings of this application are only a specific implementation method and are not restrictive. Under the guidance of this application, technicians in this field can make many forms without departing from the scope of protection of the purpose of this application and the claims, all of which are within the scope of protection of this application.

Claims

1. A mobile lightning three-dimensional positioning system, characterized by: The positioning system is composed of a vehicle-mounted ground master station (100), a plurality of airborne aerial substations (200), and a plurality of mobile aerial substations (300); the vehicle-mounted ground master station (100), the airborne aerial substation (200), and the mobile aerial substation (300) are equipped with a lightning signal collection device (400); the vehicle-mounted ground master station (100) uses a car as a ground mobile vehicle, and the airborne aerial substation (200) and the mobile aerial substation (300) use a rotary-wing unmanned aerial vehicle as an aerial mobile vehicle; The vehicle-mounted ground master station (100) is equipped with a GNSS global satellite navigation receiving device (101); the airborne aerial substation (200) and the mobile aerial substation (300) obtain GNSS global satellite navigation signals through the GNSS global satellite navigation system built into the unmanned aerial vehicle; the GNSS global satellite navigation signals are used for lightning signal timing synchronization, and the precise three-dimensional coordinates of the vehicle-mounted ground master station (100) and the airborne aerial substation (200) are obtained through real-time dynamic carrier phase differential (RTK), so that the collected lightning signals can be marked with a timestamp and the coordinates of the measuring station can be recorded at the moment of lightning occurrence; The lightning signal acquisition device (400) adopts an FPGA lightning signal high-speed data acquisition system, which is mainly composed of an FPGA logic gate circuit and an embedded ARM processor; The number of the airborne aerial substations (200) is at least four but not limited to four. Positioning data and redundant data are obtained to remove fuzzy solutions. The airborne aerial substations (200) are arranged at different heights to form a three-dimensional mobile lightning detection network with a ground layer, a low-altitude layer, and a mid-altitude layer together with the vehicle-mounted ground main station (100). The spatial form between the lightning detection network and the lightning can be adjusted according to the location where the lightning occurs by changing the arrangement of the mobile vehicle-mounted ground main station (100) and the airborne aerial substations (200), so that a larger incident angle is formed between the lightning radiation source and the lightning detection network; The mobile aerial substation (300) has the same configuration as the airborne aerial substation (200), and at least one but not limited to one is used to replace the working airborne aerial substation (200) to achieve continuous operation of the airborne aerial substation (200). The replaced airborne aerial substation (200) serves as a new mobile aerial substation (300) after replacing the battery. The airborne aerial substation (200) is equipped with a wireless signal transmitting device (201), the lightning signal collected by the lightning signal collecting device (400) is processed and modulated, each airborne aerial substation (200) transmits at a different frequency, the vehicle-mounted ground master station (100) is equipped with a wireless signal receiving device (102), the lightning signal collected by the airborne aerial substation (200) is transmitted back to the vehicle-mounted ground master station (100) by wireless means, the signal received by the wireless signal receiving device (102) is demodulated by an FSK demodulation module (103) into signals of different frequencies, and stored in a data storage device (104) of the vehicle-mounted ground master station (100); The vehicle-mounted ground master station (100) is equipped with a data processing and computing unit (105). Through the lightning signals collected by the vehicle-mounted ground master station (100) and the lightning signals transmitted back by the airborne aerial substation (200), the data processing and computing unit (105) uses a lightning positioning algorithm to calculate the three-dimensional position of the lightning radiation source.

2. The mobile lightning three-dimensional positioning system according to claim 1, characterized in that: The lightning signal acquisition device (400) adopts an FPGA lightning signal high-speed data acquisition system, which is mainly composed of an FPGA logic gate circuit and an embedded ARM processor. The FPGA logic gate circuit realizes analog-to-digital conversion control, lightning data acquisition, time stamp acquisition, pre-trigger and trigger control, wave peak acquisition, and output control. The FPGA logic gate circuit performs the functions of filtering, oversampling, Hilbert transform calculation of signal amplitude, and trigger judgment peak extraction for the acquired signal, and temporarily stores the processed data in a DDR data storage unit using DMA. After the data is processed by ARM, the corresponding data is extracted from the cache of the DDR data storage unit and stored locally. The airborne aerial substation (200) transmits the data back to the vehicle-mounted ground main station (100) through wireless means after modulation.

3. The mobile lightning three-dimensional positioning system according to claim 1, characterized in that: The vehicle-mounted ground master station (100) is equipped with a drone cluster control system (106), which can automatically control the deployment of the airborne aerial substation (200) according to a set position, and can automatically control the mobile aerial substation (300) to replace the airborne aerial substation (200) according to the set remaining power of the drone.

4. The mobile lightning three-dimensional positioning system according to claim 1, characterized in that: The lightning signal acquisition device (400) comprises a high-speed A / D conversion module (1), a GNSS signal processing unit (2), a data processing unit (3), a DDR data storage unit (4), and an ARM processing unit (5); the high-speed A / D conversion module (1) converts the analog signal output by the lightning detection sensor into a digital signal; the GNSS signal processing unit (2) outputs a high-precision clock frequency as a sampling reference clock of the high-speed A / D conversion module (1) to ensure the accuracy of the signal conversion time, and outputs a high-precision full-second clock signal 1PPS and NMEA0183 data with time information in combination with the sampling reference clock to mark a timestamp for the collected lightning signal; the GNSS signal processing unit (2) outputs RTK coordinates, and the coordinate acquisition module marks a timestamp for the coordinates and outputs the coordinates marked with the timestamp; the FPGA logic gate circuit is programmed to form a data processing unit (3) to realize analog-to-digital conversion control and lightning detection data acquisition. , timestamp acquisition, coordinate calibration, pre-trigger and trigger control, wave peak acquisition, output control, FPGA logic gate circuit filtering, oversampling, Hilbert transform calculation of signal amplitude, trigger judgment peak extraction of the signal marked with the timestamp, lightning signal and the coordinates of the marked timestamp are combined and output, the processed data is temporarily stored in the DDR data storage unit (4) using DMA, and the ARM processing unit (5) is notified to process the data; the ARM processing unit (5) embedded operating system extracts the peak data and the corresponding time information and coordinates after receiving the notification of data collection, the lightning signal collection device (400) of the vehicle-mounted ground main station (100) extracts the corresponding data and stores it in the data storage (104), and the lightning signal collection device (400) of the airborne aerial substation (200) extracts the corresponding data and stores it in the file storage unit (202), and sends it to the vehicle-mounted ground main station (100) in a wireless manner through the wireless signal transmitting device (201).

5. A mobile lightning three-dimensional positioning method according to claim 1-4, characterized in that: The steps include: S1, deploying a lightning detection network in the lightning location area, and controlling the drones of the airborne aerial substation (200) to be in position according to the set plane position and elevation through the drone cluster control system (106) of the vehicle-mounted ground master station (100); S2, the vehicle-mounted ground main station (100) and the airborne aerial substation (200) collect lightning signals; S3, setting a low-power return power threshold of the airborne aerial substation (200), when the power of the drone of any airborne aerial substation (200) is lower than the return power threshold, starting the mobile aerial substation (300) to replace the airborne aerial substation (200); S4. The data processing and computing unit (105) of the vehicle-mounted ground master station (100) obtains a number of lightning arrival locations through spatial analysis using the time difference (TDOA) of the lightning signal arriving at each measuring station, obtains an initial solution using the weighted least squares method, and then uses the obtained initial solution and constraint variables to perform a second weighted least squares method estimation to finally obtain an improved location estimate.

6. The mobile three-dimensional lightning positioning method according to claim 5, characterized in that: In the step S1, the vehicle-mounted ground master station (100) and the airborne aerial substation (200) are arranged to avoid mountains and high-rise buildings, the distance between the airborne aerial substations (200) is 5-10 km, the low-altitude layer height is 300-1000 m, and the middle-altitude layer height is 1000-2000 m. During a continuous lightning event, the positions of the vehicle-mounted ground master station (100) and the airborne aerial substation (200) are fixed; during the entire lightning event, the vehicle-mounted ground master station (100) can be moved according to the direction of the lightning occurrence, and the airborne aerial substation (200) can be controlled to change the spatial layout, so as to form an optimal spatial triangular geometric position relationship with the lightning occurrence position, thereby improving the lightning location solution accuracy.

7. The mobile three-dimensional lightning positioning method according to claim 5, characterized in that: In the step S3, the return power threshold is set to 40% to 50% of the full power of the power supply, the drone cluster control system (106) controls the mobile aerial substation (300) to fly to the drone airspace below the return power threshold, replaces the airborne aerial substation (200), replaces the battery of the replaced airborne aerial substation (200) as a new mobile aerial substation (300), replaces the airborne aerial substation (200) with the lowest voltage, and gradually replaces all the airborne aerial substations (200). After completing a round of replacement, the mobile aerial substation (300) waits for the next drone power supply to be lower than the return power threshold, and then executes the replacement of the airborne aerial substation (200).

8. The mobile three-dimensional lightning positioning method according to claim 5, characterized in that: The step S4, the time difference of arrival (TDOA) positioning, is based on the known spatial position of the master station S0 ( x 0 ,y 0 ,z 0) and substation S i The spatial position of x i ,y i ,z i ), with the spatial coordinates of the lightning radiation source P ( x, y, z ) is a variable, and the electromagnetic waves radiated by the lightning radiation source reach each substation S i The time difference to the master station S0 is Δ τ i , establish the system of equations and solve them: ， Where: Δ τ i =( τ 0 - τ i ), c is the propagation speed of electromagnetic waves, τ 0 is the time it takes for the electromagnetic wave radiated by the lightning radiation source to reach the main station, τ i is the time it takes for the electromagnetic wave radiated by the lightning radiation source to reach the substation, i =1,2,3…… n , n is the number of substations; The initial solution of the equation group is obtained, and the weighted least squares method is used to estimate the lightning position using the initial solution and constraint variables.

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