Unmanned aerial vehicle-mounted complete polarization ground penetrating radar

Abstract

The invention is suitable for the technical field of underground detection, and provides an unmanned aerial vehicle-mounted full-polarization ground penetrating radar, which comprises an unmanned aerial vehicle system used for determining a ground penetrating radar measuring network and carrying out GPS positioning; the carrying system is used for stabilizing the complete polarization ground penetrating radar system; and the fully-polarized ground penetrating radar system is suspended below the unmanned aerial vehicle system, is used for acquiring fully-polarized data of an underground target body, and comprises a PC port, a network analyzer, a switch controller, a power amplifier, a radio frequency switch and a dual-polarized antenna. According to the invention, complete polarization ground penetrating radar data can be obtained through single measurement, and the data acquisition efficiency is significantly improved; miniaturization and light weight of the unmanned aerial vehicle-mounted full-polarization ground penetrating radar are achieved, the total weight of the system does not exceed 5 kg, rapid large-range underground scanning is facilitated, and the requirement for efficient and accurate detection in complex terrains can be met; remote operation of the ground penetrating radar is achieved through the PC port, and the problem that the ground penetrating radar is difficult to control in the carrying state of the unmanned aerial vehicle is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of underground detection, and in particular relates to an unmanned aerial vehicle-borne full-polarization ground-penetrating radar. Background Art

[0002] With the development of the times, the demand for the development and utilization of underground space in fields such as geological exploration, archaeological construction, and urban construction is growing, and there is an urgent need for a method that can quickly and widely detect to improve work efficiency. In recent years, drone technology has developed rapidly, and the use of drones to carry equipment has been widely used in military and civilian fields. For underground detection, the introduction of drones to carry equipment can effectively improve detection efficiency and achieve rapid and large-scale detection.

[0003] Ground penetrating radar is a non-destructive and fast underground detection technology, which is widely used in engineering, environment, archaeology and other technical fields. It mainly uses the discontinuity and electrical differences of underground media to identify underground targets, and has many advantages such as fast, efficient, continuous and non-destructive. However, traditional ground penetrating radar still has some limitations in practical applications. On the one hand, traditional ground penetrating radar relies on manual operation, which is difficult to measure in complex terrain environments, and the scanning range is easily limited. On the other hand, traditional ground penetrating radar mainly collects single polarization data, and the information obtained is relatively limited. Although full polarization data can provide richer underground space information during the detection process, traditional single polarization ground penetrating radar can only align sampling points in point measurement when obtaining full polarization data, and the data needs to be transformed at an angle, resulting in certain errors. For conventional ground penetrating radar large-scale measurements, they are generally measured by time or distance. In the case of multiple measurements, ground penetrating radar data can only align sampling points to a limited extent, resulting in certain errors in the obtained scattering matrix, which in turn affects the accurate interpretation of underground media. Therefore, there is an urgent need for a ground penetrating radar detection device that can be large-scale, fast and rich in information. This device needs to align the sampling points as much as possible during the sampling phase to reduce the problems faced during the data processing phase. To this end, the present invention proposes an unmanned aerial vehicle-mounted fully polarized ground penetrating radar. Summary of the invention

[0004] The purpose of the present invention is to provide an unmanned aerial vehicle-mounted fully polarized ground penetrating radar, aiming to solve the problems raised in the above-mentioned background technology.

[0005] The purpose of the present invention is achieved through the following technical solutions: A fully polarized ground penetrating radar carried by an unmanned aerial vehicle, comprising: UAV system, used to carry the full polarization GPR system, determine the GPR network and perform GPS positioning; Carrying system for stabilizing the fully polarized ground penetrating radar system; A fully polarized ground penetrating radar system is suspended under the UAV system through a carrying system to obtain full polarization data of underground targets; the fully polarized ground penetrating radar system is composed of a PC port, a network analyzer, a switch controller, a power amplifier, a radio frequency switch and a dual-polarized antenna; The PC port is used to transmit control signals, operate and deploy radio frequency modules, receive and store data, and realize remote control of unmanned aerial vehicle-mounted fully polarized ground penetrating radar; the network analyzer is used to transmit and receive step-frequency electromagnetic wave signals, perform preliminary processing, and input them into the PC port for storage; the switch controller is used to receive the control signal transmitted by the PC port and switch the input level according to the control signal to control the radio frequency switch to different paths; the switch controller includes two control ports and two power ports, the two power ports supply power to the two radio frequency switches at the same time, and the two control ports are respectively connected to the two radio frequency switches and control their input levels; the power amplifier is used to receive and amplify the electrical signal of the network analyzer; the radio frequency switch is used to control the output channel of the electromagnetic wave and determine the output electromagnetic wave type, which is vertical polarization or horizontal polarization; the dual-polarization antenna is composed of two single-polarization antennas placed vertically and crossed, and is used to transmit or receive electromagnetic wave signals of different polarization directions; A measurement process of the fully polarized ground penetrating radar system is as follows: the PC port generates an electrical signal which is input into a network analyzer and a switch controller respectively; the network analyzer converts the electrical signal into a radio frequency signal; when passing through the radio frequency switch, the level of the input of the switch controller determines the output channel of the radio frequency signal; the radio frequency signal enters the dual-polarized antenna and is converted into an electromagnetic wave and emitted; electromagnetic waves of different polarizations will produce different scattering patterns on the surface of the target body; after receiving the scattered electromagnetic wave signal, another group of dual-polarized antennas transmit it back to the network analyzer through the opposite path, convert it into an electrical signal and transmit it back to the PC port for storage in the form of data; the input channel of another radio frequency switch controls the type of electromagnetic wave received and regards it as a piece of data; the high and low levels of the radio frequency switch are controlled in turn by the switch controller, and the electromagnetic wave signals of four polarization modes, namely hh, hv, vh, and vv, are measured in turn, forming a measurement, and a group of fully polarized ground penetrating radar data is obtained; a group of data is measured every 0.4s.

[0006] Furthermore, the PC port includes a power supply, an antenna, a PC host and a display; the power supply is connected to each RF module through the PC host for power supply, and is charged through the power charging port; the antenna is used to receive external control signals, and the PC port is connected to wifi through the antenna to control the remote desktop, thereby realizing remote control of the unmanned aerial vehicle-borne fully polarized ground penetrating radar; the PC host is used to transmit control signals, operate and deploy RF modules, receive and store data, and realize remote control of the unmanned aerial vehicle-borne fully polarized ground penetrating radar; the display is connected to the PC host and has a touch screen function.

[0007] Furthermore, if any one of the electromagnetic wave signals of the four polarization modes, i.e., hh, hv, vh, and vv, is measured separately, the program is adjusted on the PC side to achieve separate measurement.

[0008] Furthermore, the drone system uses a multi-rotor drone with a carrying weight of more than 7kg.

[0009] Furthermore, the mounting system is made of carbon fiber.

[0010] Furthermore, the fully polarized ground penetrating radar system does not exceed 5 kg.

[0011] Furthermore, the switch controller is directly controlled by a PC host and performs port level switching according to program input instructions.

[0012] Furthermore, the radio frequency switch is a single-knife double-throw switch, and the switching speed of the switch is 1 ms.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention can obtain full polarization ground penetrating radar data through a single measurement, which significantly improves data acquisition efficiency.

[0014] 2. The present invention realizes the miniaturization and lightweight of the UAV-mounted fully polarized ground-penetrating radar. The total weight of the system does not exceed 5 kg, which is convenient for rapid and large-scale underground scanning and can meet the needs of efficient and accurate detection in complex terrain.

[0015] 3. The present invention realizes remote operation of the ground penetrating radar through the PC port, solving the problem that the ground penetrating radar is difficult to control when mounted on a drone. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the fully polarized ground penetrating radar system.

[0017] Figure 2 It is a schematic diagram of switch signal control and receiving signal type.

[0018] Figure 3 This is a schematic diagram of the PC port.

[0019] Figure 4 Schematic diagram of a dual-polarized antenna.

[0020] In the figure: PC port 1, network analyzer 2, switch controller 3, power amplifier 4, RF switch 5, dual-polarized antenna 6, power charging port 11, power switch 12, USB slot 13, display 14, control module 15, power supply 16, PC host 17, antenna 18. DETAILED DESCRIPTION

[0021] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0022] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0023] like Figure 1-Figure 4 As shown, an embodiment of the present invention provides an unmanned aerial vehicle-mounted fully polarized ground penetrating radar system, which includes the following main parts: The UAV system is used to carry the full polarization ground penetrating radar system, determine the ground penetrating radar network and perform GPS positioning, so that the information in the radar profile is more accurate. The UAV system uses a multi-rotor UAV with a carrying weight of more than 7kg.

[0024] The carrying system is used to stabilize the fully polarized ground penetrating radar system to ensure that its shape is fixed during the detection process, so as to facilitate subsequent data processing. The carrying system is made of carbon fiber and is light in weight.

[0025] The fully polarized ground penetrating radar system is suspended under the UAV system through the carrying system to obtain the fully polarized data of the underground target. The system does not exceed 5kg and consists of a PC port 1, a network analyzer 2, a switch controller 3, a power amplifier 4, a radio frequency switch 5 and a dual-polarized antenna 6.

[0026] PC port 1 is used to transmit control signals, operate and deploy radio frequency modules (power amplifier 4, radio frequency switch 5 and network analyzer 2, etc.), receive and store data, and realize remote control of unmanned aerial vehicle fully polarized ground penetrating radar. PC port 1 includes power supply 16, antenna 18, PC host 17 and display 14. The power supply 16 is connected to each radio frequency module through PC host 17 for power supply, and is charged through power charging port 11; power supply 16 is a rechargeable power supply 16, and its battery capacity supports the fully polarized ground penetrating radar system to work continuously for more than one hour. The antenna 18 is used to receive external control signals. PC port 1 can be connected to wifi through antenna 18 to control the remote desktop and realize remote control of unmanned aerial vehicle fully polarized ground penetrating radar. The PC host 17 is used to transmit control signals, operate and deploy radio frequency modules such as switch controller 3 and network analyzer 2, receive and store data, and realize remote control of unmanned aerial vehicle fully polarized ground penetrating radar. The display 14 is connected to the PC host 17 using an HDMI cable and is powered through a USB port. It has a touch screen function and is convenient for controlling the PC host 17.

[0027] The network analyzer 2 is used for transmitting and receiving electromagnetic wave signals with a step frequency of 0.6 GHz to 6 GHz, and performing preliminary processing and inputting the signals into the PC port 1 for storage.

[0028] The switch controller 3 is used to receive the control signal transmitted by the PC port 1 and switch the input level according to the control signal, and control the RF switch 5 to switch to different paths. The switch controller 3 includes two control ports and two power ports. The two power ports simultaneously supply power to the two RF switches 5 (RF switch 1 and RF switch 2). The two control ports are respectively connected to the two RF switches 5 and control their input levels. The switch controller 3 is directly controlled by the PC host 17, and the port level is switched according to the program input instruction. The control of the switch controller 3 is as follows: Figure 2 As shown, h represents parallel polarization, v represents vertical polarization, hh and vv are electromagnetic wave signal data of horizontal polarization and vertical polarization respectively, and hv and vh are electromagnetic wave signal data of two different cross-polarizations. Figure 2 The control signal shown is a cycle (hh, hv, vh, vv), which is a set of fully polarized radar data. It is repeated many times during the measurement process to measure signals at different locations. Folders are created separately in the data storage to separate different types of polarization data; multiple data are separated for subsequent processing. Full polarization measurement (hh, hv, vh, vv) and single polarization measurement are supported, and a set of data is measured every 0.4s; single polarization measurement is specifically: if any polarization radar signal such as hh, hv, vh, vv four polarization modes need to be measured separately, separate measurement can be achieved by adjusting the program on PC port 1.

[0029] The power amplifier 4 is used to receive and amplify the electrical signal of the network analyzer 2, thereby increasing the signal propagation distance and being able to increase the power by 20 dB.

[0030] The radio frequency switch 5 is a single-knife double-throw switch, which is used to control the output channel of the electromagnetic wave and determine the type of output electromagnetic wave (horizontal polarization or vertical polarization). The switching speed is 1ms.

[0031] The dual-polarized antenna 6 is composed of two single-polarized antennas placed vertically and crossed, and is used to transmit or receive electromagnetic wave signals in different polarization directions.

[0032] In the embodiment of the present invention, the integrated design is as follows: the PC port 1, the network analyzer 2, the switch controller 3, the power amplifier 4 and the radio frequency switch 5 are integrated into one body through the connector and fixed in the square housing. The bottom of the housing has a hole, and the wire is led out from the radio frequency switch 5 through the hole to connect the dual-polarized antenna 6 under the housing. At the same time, the housing is extended downward around to form protection for the dual-polarized antenna 6. There is an openable cover on the top of the square housing, such as Figure 3As shown in the figure, a display 14, a power switch 12, a power charging port 11, a USB slot 13, etc. are arranged on it; wherein, the power switch 12 controls the connection between the power supply 16 and the PC host 17 through a simple control module 15; the power charging port 11 is directly connected to the power supply 16, so that it can be conveniently charged; the USB slot 13 is connected to the PC host 17 through a wire, and the required components can be connected externally, and the stored data can be exported through a mobile hard disk or the like.

[0033] Improvement measures: Different needs can be met by replacing or adding more RF modules, such as increasing the power of the power amplifier 4, adding an attenuator at the receiving antenna to protect the network analyzer 2, so that it can obtain deeper information while protecting the instrument safety. Different needs can be met by adding digital devices to the PC port 1, such as adding GPS to more accurately locate the area detected by the fully polarized ground penetrating radar, and adding RTK to obtain a more accurate UAV flight altitude, so as to correct the signal error caused by the terrain later. Remote control software can be installed in the PC host 17. When the UAV is equipped with a fully polarized ground penetrating radar and placed at the starting position, the ground penetrating radar system can be controlled through the remote desktop to start working, and the fully polarized ground penetrating radar system can be remotely controlled to stop working and save data at the end position. After that, the UAV can be remotely controlled to return.

[0034] In fast measurement, in order to improve the accuracy, since the hv data can be approximately equal to the vh data, the program can be modified on PC port 1 to change the high and low level output methods of switch controller 3, so that the fully polarized ground penetrating radar system can measure in the order of hh, hv, and vv as a cycle, thereby improving work efficiency.

[0035] Working principle: Manually start the drone and the fully polarized ground penetrating radar system, and connect to the external workstation through the remote desktop. After the drone flies to the starting point of the survey line and stops steadily, the fully polarized ground penetrating radar system starts measuring through remote control. The measurement process of the fully polarized ground penetrating radar system is as follows: PC port 1 transmits instructions through the python program running in the IDE, and generates electrical signals that are input into the network analyzer 2 and the switch controller 3 respectively. The network analyzer 2 converts the electrical signal into a radio frequency signal. When passing through the radio frequency switch 5, the level of the input of the switch controller 3 determines the output channel of the radio frequency signal (vertical polarization or horizontal polarization). The radio frequency signal enters the dual-polarized antenna 6 and is converted into an electromagnetic wave and emitted. Electromagnetic waves of different polarizations will produce different scattering patterns on the surface of the target body. After that, another set of dual-polarized antennas 6 receives the scattered electromagnetic wave signal, transmits it back to the network analyzer 2 through the opposite path, converts it into an electrical signal and transmits it back to the PC host 17 to store it in the form of data. The input channel of another RF switch 5 controls the type of electromagnetic wave received and regards it as a piece of data. The high and low levels of the RF switch 5 are controlled in turn through the switch controller 3, and the electromagnetic wave signals of four polarization modes (hh, hv, vh, vv) are measured in turn, forming a measurement to obtain a set of fully polarized ground penetrating radar data.

[0036] For the measured full polarization data, in the case of low-frequency electromagnetic waves and slow flight speed, it can be approximated as data at the same position and a scattering matrix can be constructed for subsequent processing. If the speed is fast, the data is aligned by interpolation. Since the flight speed of the drone does not change much within a cycle, it can be approximated as uniform flight. Therefore, the full polarization data obtained by interpolation can be considered to be at the same position, so it can reasonably construct a scattering matrix, and the authenticity of its subsequent processing can be greatly improved. The interpolation method is to establish a position matrix, that is, to arrange the navigation distance horizontally according to the data density required, and establish the position matrix corresponding to the four polarization modes for the positions corresponding to the four polarization modes, and its size is one-fourth of the large position matrix. After that, these four position matrices are used to interpolate the full polarization matrix to the size of the large position matrix. At this time, the position of the full polarization data is aligned and can be transformed into a scattering matrix.

[0037] The fully polarized ground penetrating radar system of the present invention can receive electromagnetic waves from different polarization directions, and utilize the differences in vector characteristics in the electromagnetic wave signals reflected from different targets and the relationship between each vector component to more accurately obtain information such as the position and direction of the target. It studies the polarization characteristics of the target and uses polarization decomposition methods such as Freeman decomposition and H-α decomposition to obtain target characteristics. Compared with single-polarization ground penetrating radar signals, the information obtained by this system is more comprehensive and accurate, and can better achieve accurate description of underground targets.

[0038] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. An unmanned aerial vehicle-borne fully polarized ground penetrating radar, characterized in that: include: UAV system, used to carry the full polarization GPR system, determine the GPR network and perform GPS positioning; Carrying system for stabilizing the fully polarized ground penetrating radar system; A fully polarized ground penetrating radar system is suspended under the UAV system through a carrying system to obtain full polarization data of underground targets; the fully polarized ground penetrating radar system is composed of a PC port, a network analyzer, a switch controller, a power amplifier, a radio frequency switch and a dual-polarized antenna; The PC port is used to transmit control signals, operate and deploy radio frequency modules, receive and store data, and realize remote control of the fully polarized ground penetrating radar on the unmanned aerial vehicle; the network analyzer is used to transmit and receive step-frequency electromagnetic wave signals, perform preliminary processing, and input them into the PC port for storage; the switch controller is used to receive the control signal transmitted by the PC port and switch the input level according to the control signal, and control the radio frequency switch to switch to different paths; The switch controller comprises two control ports and two power ports, the two power ports supply power to the two RF switches at the same time, and the two control ports are respectively connected to the two RF switches and control their input levels; the power amplifier is used to receive and amplify the electrical signal of the network analyzer; the RF switch is used to control the output channel of the electromagnetic wave and determine the output electromagnetic wave type, which is vertical polarization or horizontal polarization; the dual-polarization antenna is composed of two single-polarization antennas placed vertically and crossed, and is used to transmit or receive electromagnetic wave signals of different polarization directions; A measurement process of the fully polarized ground penetrating radar system is as follows: the PC port generates an electrical signal which is input into a network analyzer and a switch controller respectively; the network analyzer converts the electrical signal into a radio frequency signal; when passing through the radio frequency switch, the level of the input of the switch controller determines the output channel of the radio frequency signal; the radio frequency signal enters the dual-polarized antenna and is converted into an electromagnetic wave and emitted; electromagnetic waves of different polarizations will produce different scattering patterns on the surface of the target body; after receiving the scattered electromagnetic wave signal, another group of dual-polarized antennas transmit it back to the network analyzer through the opposite path, convert it into an electrical signal and transmit it back to the PC port for storage in the form of data; the input channel of another radio frequency switch controls the type of electromagnetic wave received and regards it as a piece of data; the high and low levels of the radio frequency switch are controlled in turn by the switch controller, and the electromagnetic wave signals of four polarization modes, namely hh, hv, vh, and vv, are measured in turn, forming a measurement, and a group of fully polarized ground penetrating radar data is obtained; a group of data is measured every 0.4s.

2. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: The PC port includes a power supply, an antenna, a PC host and a display; the power supply is connected to each RF module through the PC host for power supply, and is charged through the power charging port; the antenna is used to receive external control signals, and the PC port is connected to wifi through the antenna to control the remote desktop, thereby realizing remote control of the unmanned aerial vehicle-borne fully polarized ground penetrating radar; the PC host is used to transmit control signals, operate and deploy RF modules, receive and store data, and realize remote control of the unmanned aerial vehicle-borne fully polarized ground penetrating radar; The display is connected to the PC host and has a touch screen function.

3. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: If any one of the electromagnetic wave signals of the four polarization modes, i.e., hh, hv, vh, and vv, is measured separately, the program is adjusted on the PC side to achieve separate measurement.

4. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: The UAV system adopts a multi-rotor UAV with a carrying weight of more than 7kg.

5. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: The mounting system is made of carbon fiber.

6. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: The fully polarized ground penetrating radar system does not exceed 5 kg.

7. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: The switch controller is directly controlled by the PC host and performs port level switching according to program input instructions.

8. The UAV-borne fully polarized ground penetrating radar according to claim 1, characterized in that: The radio frequency switch is a single-knife double-throw switch, and the switching speed is 1ms.

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