Non-fuzzy cooperation node orientation detection method and system based on double antennas

Abstract

The invention provides a double-antenna-based non-fuzzy cooperative node orientation detection method and system, and relates to the field of anchor-point-free cooperative localization, and the method comprises the steps: receiving a cooperative node transmitting signal through a static antenna and a mobile antenna, and obtaining static antenna data and rotating antenna data; calculating a channel ratio based on the wireless channel value of the stationary antenna data and the wireless channel value of the rotating antenna data; performing spatial filtering on the channel ratio based on a circular SAR model to obtain a spatial spectrogram; and extracting peak points in the spatial spectrogram to obtain azimuth angle estimated values of the cooperative nodes, thereby realizing non-fuzzy multi-cooperative-node azimuth detection. According to the invention, high-precision, fuzzy-free, low-complexity and clock-synchronization-free multi-cooperative-node orientation detection can be realized by adopting double-antenna configuration, anchor-point-free cooperative positioning is implemented, and deployment of multifunctional comprehensive radio frequency sensing network nodes is helped to adapt to multi-scene sensing and information fusion requirements in military and civil fields.

Description

Technical Field

[0001] The present application relates to the field of anchor-free collaborative positioning, and in particular to a dual-antenna-based unambiguous collaborative node position detection method and system. Background Art

[0002] In recent years, the anchor-free collaborative positioning technology, which only estimates the relative position of nodes through wireless measurement and information sharing between nodes and neighboring nodes, has gradually attracted attention due to its wide application potential in complex environments. It has become a research hotspot in the fields of intelligent transportation, industrial automation, emergency rescue, smart cities, environmental monitoring, and national defense security. In a two-dimensional plane, the two elements of distance and azimuth can uniquely establish a relative position. Therefore, accurately estimating the direction of the incident wave from the neighboring collaborative nodes is the key content of anchor-free collaborative positioning research. At present, passive direction finding technology is developing rapidly at home and abroad, but the traditional passive direction finding system requires at least three antennas to form an array to receive signals to achieve a higher angular resolution, and phase ambiguity needs to be considered, which makes the system structure complex and costly. Summary of the invention

[0003] The purpose of the present invention is to provide a dual-antenna-based unambiguous collaborative node direction detection method and system in order to solve the problems of complex system construction and high construction cost caused by the need to configure antenna arrays and strict clock synchronization in existing passive direction finding schemes in collaborative positioning, which makes the system structure complex and the cost high.

[0004] The above-mentioned purpose of the present application is achieved through the following technical solutions: S1: Receive the signal transmitted by the cooperative node through the static antenna and the mobile antenna to obtain the static antenna data and the rotating antenna data; S2: Wireless channel value based on rotating antenna data and the wireless channel value with the stationary antenna data , calculate the channel ratio; S3: Based on the circular SAR model, the channel ratio is spatially filtered to obtain a spatial spectrum. The peak points in the spatial spectrum are extracted to obtain the azimuth estimation value of the cooperative node, thereby realizing unambiguous azimuth detection of multiple cooperative nodes.

[0005] Optionally, step S2 includes: The static antenna and the mobile antenna receive signals simultaneously, and the time steps of the static antenna data and the rotating antenna data are the same;

[0006] in, represents the cumulative phase; Calculate the wireless channel ratio, the formula is as follows:

[0007] in, Relatively constant over a short period of time.

[0008] Optionally, step S3 includes: Substitute the channel ratio into the circular SAR formula, adjust the weight to enhance the signal strength in the direction of the cooperative node, and perform spatial filtering.

[0009] A dual-antenna-based unambiguous cooperative node position detection system, the system comprising: an antenna unit, a radio frequency front-end module and an FPGA signal processing unit; The antenna unit includes: a stationary antenna and a rotating antenna; The radio frequency front-end module is used to send and receive radio frequency signals; The antenna unit is used to receive signals transmitted by the cooperative node and obtain stationary antenna data and rotating antenna data; The FPGA signal processing unit is used to calculate the wireless channel value based on the rotating antenna data. and the wireless channel value with the stationary antenna data , calculate the channel ratio; The FPGA signal processing unit is also used to perform spatial filtering on the channel ratio based on the circular SAR model to obtain a spatial spectrum; extract peak points in the spatial spectrum to obtain azimuth estimation values ​​of the collaborative nodes, thereby realizing unambiguous azimuth detection of multiple collaborative nodes.

[0010] Optionally, the antenna unit is connected to an FPGA signal processing unit; The radio frequency front-end module is connected to the FPGA signal processing unit.

[0011] Optionally, the antenna unit adopts a 2-transmit 2-receive omnidirectional broadband antenna with a frequency range of 600MHz to 6000MHz.

[0012] Optionally, the FPGA signal processing unit adopts a heterogeneous architecture ZYNQMP FPGA.

[0013] A computer-readable storage medium stores instructions. When the instructions are executed, an unambiguous cooperative node position detection method based on dual antennas is executed.

[0014] The beneficial effects of the technical solution provided by this application are: The present invention is based on a circular synthetic aperture radar (SAR) model, uses a rotating antenna to receive data, and combines a stationary antenna to form a wireless channel ratio and perform spatial filtering, thereby constructing a multi-cooperative node azimuth detection method that is high-precision, unambiguous, low-complexity, and does not require clock synchronization without anchor point assistance, so as to further reduce system complexity and construction costs. The method of using a static and a dynamic dual antenna to receive data realizes unambiguous multi-cooperative node azimuth detection, does not require antenna arrays and clock synchronization, reduces system complexity and construction costs, and is used in the fields of intelligent transportation, unmanned aerial vehicle systems, industrial automation, emergency rescue, smart cities, and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present application will be further described below with reference to the accompanying drawings and embodiments, in which: Figure 1 It is a non-ambiguous cooperative node position detection model diagram in an embodiment of the present application; Figure 2 It is an overall block diagram of the anchor-free collaborative positioning system in an embodiment of the present application; Figure 3 is a flow chart in an embodiment of the present application; Figure 4 is a single target experimental scene diagram in an embodiment of the present application; Figure 5 This is a diagram of the experimental results of a single target direction finding scenario in an embodiment of the present application; Figure 6 is a multi-target experimental scene diagram in an embodiment of the present application; Figure 7 It is a diagram of the experimental results of the multi-target direction finding scenario in the embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described in detail with reference to the accompanying drawings.

[0017] An embodiment of the present application provides an unambiguous cooperative node position detection method based on dual antennas.

[0018] Please refer to Figure 1 , Figure 1 It is an unambiguous cooperative node position detection model diagram of an unambiguous cooperative node position detection method based on dual antennas in an embodiment of the present application, including: S1: Receive the signal transmitted by the cooperative node through the static antenna and the mobile antenna to obtain the static antenna data and the rotating antenna data; S2: Wireless channel value based on rotating antenna data and the wireless channel value with the stationary antenna data , calculate the channel ratio; S3: Based on the circular SAR model, the channel ratio is spatially filtered to obtain a spatial spectrum. The peak points in the spatial spectrum are extracted to obtain the azimuth estimation value of the cooperative node, thereby realizing unambiguous azimuth detection of multiple cooperative nodes.

[0019] Specifically, the embedded radio transceiver platform is used as the hardware basis, and a static and a dynamic dual antenna are used to receive data. The ratio of the two wireless channels is taken to eliminate the phase difference between the independent transceiver devices, and the weight is adjusted at the same time. The circular SAR model is deployed on the platform, and with the corresponding accessories, unambiguous cooperative node position detection can be implemented.

[0020] Specifically, based on a circular synthetic aperture radar (SAR) model, a rotating antenna is used to receive data, and a stationary antenna is combined to form a wireless channel ratio and perform spatial filtering.

[0021] Step S2 includes: The static antenna and the mobile antenna receive signals simultaneously, and the time steps of the static antenna data and the rotating antenna data are the same;

[0022] in, represents the cumulative phase; Calculate the wireless channel ratio, the formula is as follows:

[0023] in, Relatively constant over a short period of time.

[0024] In one embodiment, the unambiguous cooperative node position detection model diagram based on dual antennas is as follows: Figure 1 As shown in the figure, the transmission and reception are completed on independent devices. The receiving device consists of a stationary antenna and a mobile antenna. The mobile antenna moves along a circle with a radius of r, similar to a circular synthetic aperture radar. Since the transmission and reception work on SAR used the same reference clock, the wireless channel value of the mobile antenna measured It has nothing to do with frequency, that is, But in reality, SAR is performed between independent transmitters and receivers, and the wireless channel measured is Due to position changes, carrier and sampling frequency offsets between the transmitter and receiver, and phase noise, there will be To eliminate this accumulated phase ,like Figure 1 As shown, one stationary antenna and one mobile antenna are used for reception.

[0025] It is relatively constant in a short time, so the wireless channel ratio is It is a constant multiple of the mobile channel, and there is no phase accumulation caused by frequency deviation and noise, so it is used Substitute it into the SAR formula, and adjust the weight to enhance the signal strength in the incoming wave direction to achieve spatial filtering, thereby equivalently obtaining the result of the wireless receiver performing SAR analysis on the incoming wave signal without frequency offset and signal noise accumulation, realizing unambiguous cooperative node azimuth detection based on dual antennas, reducing system complexity and construction costs, and without clock synchronization requirements. The technical solution of the present application can identify multiple incoming wave directions, which is specifically manifested in that a corresponding peak will appear at each incoming wave direction in the spatial spectrum after data processing.

[0026] Step S3 includes: Substitute the channel ratio into the circular SAR formula, adjust the weight to enhance the signal strength in the direction of the cooperative node, and perform spatial filtering.

[0027] A dual-antenna-based unambiguous cooperative node position detection system, the system comprising: an antenna unit, a radio frequency front-end module and an FPGA signal processing unit; The antenna unit includes: a stationary antenna and a rotating antenna; The radio frequency front-end module is used to send and receive radio frequency signals; The antenna unit is used to receive signals transmitted by the cooperative node and obtain stationary antenna data and rotating antenna data; The FPGA signal processing unit is used to calculate the wireless channel value based on the rotating antenna data. and the wireless channel value with the stationary antenna data , calculate the channel ratio; The FPGA signal processing unit is also used to perform spatial filtering on the channel ratio based on the circular SAR model to obtain a spatial spectrum; extract peak points in the spatial spectrum to obtain azimuth estimation values ​​of the collaborative nodes, thereby realizing unambiguous azimuth detection of multiple collaborative nodes.

[0028] The antenna unit is connected to the FPGA signal processing unit; The radio frequency front-end module is connected to the FPGA signal processing unit.

[0029] The antenna unit adopts an omnidirectional broadband antenna with 2 transmit and 2 receive functions, and the frequency range is 600MHz to 6000MHz.

[0030] In one embodiment, the overall block diagram of the anchor-free collaborative positioning system used in the present invention is as follows. Figure 2As shown. The overall system is divided into three parts: antenna unit, RF front-end module and FPGA signal processing unit. The antenna unit uses a 2-transmit 2-receive omnidirectional broadband antenna with a frequency range from 600MHz to 6000MHz; the RF front-end module mainly completes the corresponding signal up and down conversion, digital-to-analog conversion and RF signal transmission and reception; the FPGA signal processing unit mainly completes the corresponding signal generation, reception, processing and other algorithms.

[0031] The FPGA signal processing unit adopts a heterogeneous architecture ZYNQMP FPGA.

[0032] In one embodiment, since the collaborative positioning RF sensor is usually carried on an outdoor mobile platform such as an unmanned vehicle or a drone, certain requirements are placed on the size and power consumption of the sensor. Therefore, the present invention designs a RF front-end solution based on the RF transceiver integrated chip ADRV9009. The chip contains four independent communication links of 2 receiving and 2 transmitting, which can realize the transceiver of ultra-wideband RF signals from 75MHz to 6000MHz. The core control unit adopts Xilinx's heterogeneous architecture ZYNQMP FPGA, which is composed of resource-rich FPGA logic (Programmable Logic, PL) and 4 ARM architecture 53 hard-core processing systems (Processing System, PS). Most digital signal processing (DSP) tasks, such as filtering, sequence capture and tracking, azimuth arrival angle solution and distance estimation, are completed in the core control unit.

[0033] In one embodiment, Figure 3 The implementation scheme of unambiguous cooperative node azimuth detection based on dual antennas is given. The embedded radio transceiver platform converts the acquired cooperative node transmission signal from analog signal to digital signal after being collected by the ADC of the RF front end and inputs it into the FPGA for subsequent signal processing. At the FPGA digital end, after being processed by the low-pass filter, the ratio of the two wireless channels is taken to eliminate the phase difference between the independent transceiver devices. The weight is adjusted, and the channel ratio is spatially filtered based on the circular SAR formula. Finally, the peak point in the obtained spatial spectrum is extracted to realize the azimuth detection of the cooperative node in the line-of-sight scenario.

[0034] Embodiment 1: Select and Figure 1 The experimental scenario consistent with the model shown in the figure is used to verify the single target direction finding. Figure 4As shown in the figure, the positioning system is deployed in a dark room with weak external multipath interference. The transmitting and receiving antennas use directional antennas and omnidirectional antennas as shown in the figure, with a transmission power of 26 dBm. The rotating antenna and RF sensor at the receiving end are fixed on a device that can be electrically controlled to rotate 360 ​​degrees horizontally, seamlessly and continuously with high precision. The antenna rotation radius is 0.28m, and the stationary antenna is placed close to the rotating platform.

[0035] by Figure 4 The coordinate system shown is used as a reference. The target Tx azimuth angles are set to 90°, 80.54°, and 62.8° by moving the transmitting antenna position. The turntable at the receiving end drives the rotating antenna to move. The current angular position of the rotating antenna is recorded every 10° movement, and the data received by the rotating antenna and the stationary antenna are saved. A total of 36 groups are saved, and the azimuth angle of the collaborative node is estimated by analyzing the received data.

[0036] Use MATLAB to analyze the data received by the antenna and draw a multipath profile diagram. Figure 5 As shown in the figure, the horizontal axis is the spatial angle, and the vertical axis represents the power spectrum amplitude. (a), (b), and (c) respectively show the results of azimuth detection of Amplitude Modulated (AM) and Frequency Modulated (FM) signals when the actual incoming wave directions are 90°, 80.54°, and 62.8°. The angle corresponding to the peak in each sub-figure is the measured incoming wave direction, from which the error table can be obtained, as shown in Table 1: Table 1

[0037] In the experimental result diagram, there is only one obvious beam in each sub-diagram, and its amplitude is greatly different from the amplitudes of other side lobes. The angle corresponding to the beam and the actual incoming wave direction have an error within 1.8°, and the experimental results are relatively ideal.

[0038] Embodiment 2: Next, we conduct experimental verification in a multi-objective scenario. Figure 6 As shown, in Figure 4 On the basis, a metal plate is placed to create a reflection path, and the waveform is verified to be an FM signal and a sine signal, both of which have a carrier frequency of 2.56GHz. The signal reaches the receiving end along the direct path and the reflection path with azimuth angles of 116.00° and 132.78° respectively. The other parameters and experimental conditions are the same as those in Example 1. The experimental results are shown in Figure 7 As shown: Figure 7 There are two obvious peaks in each sub-graph, corresponding to the azimuth angles of the signal reaching the receiving end via two paths. By observing the angles corresponding to the peaks, we can get the error table as shown in Table 2: Table 2

[0039] The error between the estimated value of the incoming wave direction and the actual azimuth angle is within 1.5°, which once again proves that the invention can detect multiple incoming wave directions. The results of Examples 1 and 2 are all single measurement results. As the number of measurements increases, the angle estimation error will be lower, basically within 1°.

[0040] The present application also discloses a computer-readable storage medium storing a plurality of instructions, wherein the instructions are suitable for a processor to load to execute the above-mentioned method for unambiguous cooperative node position detection based on dual antennas.

[0041] The above are only exemplary embodiments of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure.

[0042] This application is intended to cover any variation, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art not described in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A dual-antenna-based unambiguous cooperative node position detection method, characterized in that: The method comprises the following steps: S1: Receive the signal transmitted by the cooperative node through the static antenna and the mobile antenna to obtain the static antenna data and the rotating antenna data; S2: Wireless channel value based on rotating antenna data and the wireless channel value with the stationary antenna data , calculate the channel ratio; S3: Based on the circular SAR model, the channel ratio is spatially filtered to obtain a spatial spectrum. The peak points in the spatial spectrum are extracted to obtain the azimuth estimation value of the cooperative node, thereby realizing unambiguous azimuth detection of multiple cooperative nodes.

2. The method for unambiguous cooperative node position detection based on dual antennas according to claim 1, characterized in that: Step S2 includes: The static antenna and the mobile antenna receive signals simultaneously, and the time steps of the static antenna data and the rotating antenna data are the same; in, represents the cumulative phase; Calculate the wireless channel ratio, the formula is as follows: in, Relatively constant over a short period of time.

3. The method for unambiguous cooperative node position detection based on dual antennas according to claim 1, characterized in that: Step S3 includes: Substitute the channel ratio into the circular SAR formula, adjust the weight to enhance the signal strength in the direction of the cooperative node, and perform spatial filtering.

4. A dual-antenna-based unambiguous cooperative node position detection system, used to implement a dual-antenna-based unambiguous cooperative node position detection method as described in any one of claims 1 to 3, characterized in that: The system comprises: an antenna unit, a radio frequency front-end module and an FPGA signal processing unit; The antenna unit includes: a stationary antenna and a rotating antenna; The radio frequency front-end module is used to send and receive radio frequency signals; The antenna unit is used to receive signals transmitted by the cooperative node and obtain stationary antenna data and rotating antenna data; The FPGA signal processing unit is used to calculate the wireless channel value based on the rotating antenna data. and the wireless channel value with the stationary antenna data , calculate the channel ratio; The FPGA signal processing unit is also used to perform spatial filtering on the channel ratio based on the circular SAR model to obtain a spatial spectrum; extract peak points in the spatial spectrum to obtain azimuth estimation values ​​of the collaborative nodes, thereby realizing unambiguous azimuth detection of multiple collaborative nodes.

5. The dual-antenna-based unambiguous cooperative node position detection system according to claim 4, characterized in that: The antenna unit is connected to the FPGA signal processing unit; The radio frequency front-end module is connected to the FPGA signal processing unit.

6. The dual-antenna-based unambiguous cooperative node position detection system according to claim 4, characterized in that: The antenna unit adopts an omnidirectional broadband antenna with 2 transmit and 2 receive functions, and the frequency range is 600MHz to 6000MHz.

7. The dual-antenna-based unambiguous cooperative node position detection system according to claim 4, characterized in that: The FPGA signal processing unit adopts a heterogeneous architecture ZYNQMP FPGA.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed by a computer, the method according to any one of claims 1 to 3 is executed.

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