Positioning method for indoor dual-antenna reception based on carrier phase difference optimization

Abstract

The present invention discloses an indoor dual-antenna positioning method based on carrier phase difference optimization. The method first installs two pseudolites indoors to transmit signals and messages in a GPS standard format. A dual-antenna receiving terminal is installed on a device that requires positioning information. A carrier phase reference error from the receiving terminal to the pseudolites is then obtained. During the positioning process, the receiving terminal receives pseudolites' message signals. The carrier phase differences between pseudolites 1 and 2 and receiving antennas A and B are calculated based on the carrier phase conditions. The distance differences between the pseudolites and receiving antennas A and B are calculated using the carrier phase differences. An optimization model is established to minimize the residual error between the measured carrier phase difference and the theoretically calculated carrier phase difference. The optimization algorithm is then used to solve the position data of the dual-antenna receiving terminal, thereby achieving indoor positioning.

Description

Technical Field

[0001] The present invention belongs to the field of navigation and positioning technology, and in particular relates to an indoor dual-antenna reception positioning method based on carrier phase difference optimization solution. Background Art

[0002] With the acceleration of urbanization and the development of technologies such as the Internet of Things and mobile computing, people's demand for location services is no longer limited to outdoor locations. Indoor positioning services have become a hot research topic. The carrier phase measurement method in satellite navigation is widely used in satellite navigation positioning. Positioning can be achieved by obtaining the carrier phase value and calculating the inverse pseudorange. High-precision positioning can also be achieved by comparing the phase difference of the carrier and inverting it. The Global Navigation Satellite System (GNSS) performs well in outdoor high-precision positioning. However, in indoor environments with complex environments and significant signal attenuation, scattering, and multipath effects, GNSS signals are severely interfered with. To achieve high-precision indoor positioning, researchers have proposed a variety of methods, including pseudo-satellite technology, Wi-Fi positioning, Bluetooth positioning, and ultra-wideband (UWB) technology.

[0003] However, while UWB positioning offers high accuracy and good obstacle penetration, it struggles to achieve wide coverage and is costly. Zigbee uses RSSI for positioning, offering high security and low power consumption, but it has high algorithm requirements and struggles to achieve synchronized positioning in complex environments. Bluetooth positioning is widely used due to its small size, low power consumption, and ease of integration into mobile terminals. However, it is susceptible to electromagnetic interference and requires a local area network, leading to high costs. Geomagnetic positioning can encounter feature similarity issues indoors, placing high demands on the algorithm's feature extraction capabilities and robustness.

[0004] In summary, there are still many problems that need to be solved in order to fully and accurately realize positioning and navigation in complex indoor environments. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes an indoor dual-antenna reception positioning method based on carrier phase difference optimization solution. Pseudo-satellites are arranged at reasonable locations indoors to provide reliable GNSS-like signals for indoor positioning, optimize the configuration of the receiving terminal, and use carrier phase difference measurement solution to achieve high-precision indoor positioning.

[0006] The positioning method for indoor dual-antenna reception based on carrier phase difference optimization solution specifically includes the following steps:

[0007] Step 1: Install two pseudolites indoors. The two-dimensional position coordinates of pseudolites 1 and 2 are recorded as S1 (X1, Y1) and S2 (X2, Y2), respectively. The message sent by the pseudolites is in the standard GPS format and includes the two-dimensional position of the pseudolites, pseudolites number, spreading code number, pseudolites signal status, and signal transmission time.

[0008] A dual-antenna receiving terminal is installed on the device that needs to obtain positioning information. The dual-antenna receiving terminal includes receiving antennas A and B. The straight-line distance between the receiving antennas A and B is is 0.5~1 carrier wavelength λ, and the position coordinates are recorded as (X a ,Y a )、(X b ,Y b ) is the positioning point to be found.

[0009] Preferably, signal coverage simulation software is used to simulate the signal coverage results of pseudolites installed in different positions, and the pseudolites position installation plan is determined according to the simulation results to reduce the impact of indoor occlusion.

[0010] Step 2: Before measuring the carrier phase, the baseline vector direction of the receiving antenna pair needs to be perpendicular to the direction of a pseudolite. At this time, the distance between the pseudolite and the receiving antennas A and B is equal. Theoretically, the carrier phase difference between the pseudolite and the receiving antennas A and B should be 0. However, there will be errors in practice. Extract the carrier phase value θ from the pseudolite to the receiving antennas A and B. a0 ,θ b0 , calculate the reference error θε=θ a0 -θ b0 .

[0011] Step 3: The dual-antenna receiving terminal receives the positioning signal sent by the pseudolite and demodulates the message to perform carrier phase measurement. The carrier phase difference between the pseudolite received by receiving antennas A and B at the same time is calculated and corrected using the reference error. After correction, the carrier phase differences from pseudolite 1 and pseudolite 2 to receiving antennas A and B are:

[0012] △θ1 =(θ 1a -θ 1b -θε)

[0013] △θ2=(θ 2a -θ 2b -θε)

[0014] Among them, θ 1a ,θ 1b are the carrier phase data of receiving antennas A, B and pseudo-satellite 1, θ 2a ,θ 2b They are the carrier phase data of receiving antennas A, B and pseudolite 2 respectively.

[0015] Using the carrier phase difference, calculate the distance difference between pseudolite 1 and pseudolite 2 and receiving antennas A and B respectively 、 :

[0016] =

[0017]

[0018] Step 4: The distance difference between the pseudo-satellite and different receiving antennas calculated in step 3 、 Import the objective function and add constraints to establish an optimization model that minimizes the residual between the measured carrier phase difference and the theoretically calculated carrier phase difference:

[0019]

[0020]

[0021]

[0022]

[0023] Where f(x,y) is the objective function, which represents the measure of the position error; Δd1 and Δd2 represent the theoretical distance differences from pseudolites 1 and 2 to the phase centers of receiving antennas A and B, respectively:

[0024]

[0025]

[0026] X min and X max They represent the minimum and maximum values ​​of the X axis of the indoor area after the coordinate axis is fixed; min and Y max They represent the minimum and maximum Y-axis values ​​of the indoor area after the coordinate axis is fixed.

[0027] Step 5: Solve the optimization model to obtain the location of the receiving terminal

[0028] Select the optimization algorithm, give the initial coordinate values ​​of the receiving antennas A and B, and iterate the objective function established in step 4 multiple times to solve When the objective function value is minimized and is less than the set threshold, the iterative result is output as the position data of the dual-antenna receiving terminal to achieve indoor positioning.

[0029] Preferably, the selected optimization algorithm may be Sequental Quadratic Programming Method (SQP) or Interior Point Method.

[0030] Preferably, when the dual-antenna receiving terminal first receives a pseudolite signal, the state of the point to be located is considered to be moving from outdoor to indoor, and the gate position or the last outdoor location of the point to be located is selected as the initial coordinate value. If the point to be located moves indoors, the previous location result is selected as the initial coordinate value.

[0031] The present invention has the following beneficial effects:

[0032] 1. High-precision positioning: By utilizing carrier phase difference measurement and optimization, high-precision positioning can be achieved in indoor environments. Compared with traditional indoor positioning methods, it can achieve higher positioning accuracy at a lower cost and is easier to maintain.

[0033] 2. Low cost and high efficiency: Compared with other high-precision positioning methods such as UWB, this method has a lower cost and can achieve efficient positioning without significantly increasing the complexity of hardware.

[0034] 3. Application in multiple positioning scenarios: This method can be extended to multiple different scenarios such as industrial environments and warehouse management. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a positioning method for indoor dual-antenna reception based on carrier phase difference optimization solution;

[0036] Figure 2 1 is a schematic diagram of a field test in the embodiment;

[0037] Figure 3 is the initial carrier phase reference error correction parameter;

[0038] Figure 4 is the carrier phase difference value of pseudolite 1 in the embodiment;

[0039] Figure 5 is the carrier phase difference value of pseudolite 2 in the embodiment;

[0040] Figure 6 is a schematic diagram of multiple groups of positioning results obtained in the embodiment;

[0041] Figure 7 is an error statistical diagram of multiple groups of positioning results in the embodiment. DETAILED DESCRIPTION

[0042] The present invention will be further explained below with reference to the accompanying drawings:

[0043] like Figure 1 As shown in the figure, the indoor dual-antenna positioning method based on carrier phase difference optimization solves indoor positioning by utilizing indoor pseudolites and a high-precision dual-antenna receiving terminal. By collecting measurement data such as carrier phase, calculation and optimization are performed to achieve indoor positioning. The following describes the actual process of indoor positioning testing using this method.

[0044] Step 1: Select a confined space on the fifth floor of an office building as the experimental test site to effectively reduce outdoor satellite interference. Figure 2 As shown, the site size is approximately 800*1000 (cm). Two pseudolites are installed on the edge of one side of the site. The coordinate system is established with the center of the baseline of the entrance and exit gate of this laboratory as the origin, and 1 cm is a unit length. The two-dimensional position coordinates of pseudolites 1 and 2 are (-100, 700) and (200, 700) respectively. The straight-line distance between receiving antennas A and B needs to be solved. The distance between the two satellites is 20cm, and the position coordinates are (-10, 0) and (10, 0). The message sent by the pseudo-satellite is in the GPS standard format, with a carrier base frequency of 10.23Mhz, which is converted to L1 band 1575.42Mhz after up-conversion.

[0045] Step 2: If Figure 3 As shown, the baseline vector direction of the receiving antenna pair is perpendicular to the direction of a pseudo-satellite, and the carrier phase value θ from the pseudo-satellite to the receiving antennas A and B is extracted. a0 ,θ b0 , calculate the reference error θε=θ a0 -θ b0 In this embodiment, the average value after multiple measurements is taken, θε=-0.597.

[0046] Step 3: The dual-antenna receiving terminal receives the message sent by the pseudolite and demodulates it to obtain the carrier phase information. The output data is in NMEA and CASIC formats and includes time information, carrier phase information, and pseudolite position coordinates. Carrier phase information and other information are stored in the CASIC protocol format. The RXM-MEASX field (0x03 0x10), which stores measurement information, is found and the receiving terminal's carrier phase information is extracted from the payload.

[0047] The relationship between pseudorange ρ and carrier phase difference is:

[0048]

[0049]

[0050] They represent the fractional part of the carrier phase of the positioning signal transmitted by the receiving antennas A and B to the pseudo-satellite at time t, λ is the carrier wavelength of the navigation satellite signal L1, N A With N B are the carrier phase integer ambiguities of the propagation distances from the pseudo-satellite to the receiving antennas A and B. By taking the difference between the two equations, the carrier phase difference data can be obtained as

[0051]

[0052] Among them, d A with d B Respectively represent the distances between the pseudo-satellite and the observation receiving terminal antenna A and antenna B, (N a -N b ) is the difference in integer ambiguity. The value of Na-Nb is related to the initial position, initial attitude, and initial error. The value can be determined based on the initial state as a priori conditions. Therefore, the carrier phase difference received by the receiving terminal can reflect the pseudorange difference information. When the position of the pseudo-satellite coordinate point is known, the carrier phase information has a certain functional relationship with the position information of the receiving antenna:

[0053]

[0054] This method calculates the carrier phase difference of pseudolites received by antennas A and B at the same time and uses the reference error θε to make corrections. Taking one of the test results in the actual test as an example, the carrier phase information of pseudolites 1 and 2 before correction is as follows: Figure 4 、 5 As shown in the figure, the carrier phase difference data of the two dual-antenna receiving terminals to pseudo-satellite 1 before correction is -0.2067. After eliminating the reference error The carrier phase difference data of the two dual-antenna receiving terminals to pseudo-satellite 2 is -0.147, and the data is 0.2374 after the error is eliminated. After obtaining the carrier phase difference information, the carrier phase difference information is converted into pseudorange difference information. According to the carrier phase difference information, the pseudorange difference is calculated:

[0055]

[0056]

[0057] Step 4: The distance difference between the pseudo-satellite and different receiving antennas calculated in step 3 、 Import the objective function and add constraints to establish an optimization model that minimizes the residual between the measured carrier phase difference and the theoretically calculated carrier phase difference:

[0058]

[0059]

[0060]

[0061]

[0062] Among them, X min and X max They represent the minimum and maximum values ​​of the X axis of the indoor area after the coordinate axis is fixed; min and Y max They represent the minimum and maximum values ​​of the Y axis of the indoor area after the coordinate axes are fixed; f(x,y) is the objective function, which represents the measurement of the position error; △d1 and △d2 represent the theoretical distance differences from pseudolite 1 and 2 to the phase centers of receiving antennas A and B, respectively:

[0063]

[0064]

[0065] In this embodiment, according to the size of the indoor space, the iterative point boundary is limited to: min =-500,X max =500; Y min =-100,Y max = 700. This can reduce the number of iterations and prevent the occurrence of invalid points.

[0066] Step 5: Solve the optimization model to obtain the location of the receiving terminal

[0067] This embodiment uses the sequential quadratic programming (SQP) algorithm. Given the initial coordinate values ​​of the receiving antennas A and B, the objective function established in step 4 is iterated multiple times. When the objective function value is minimized and less than a set threshold, the iterative result is output as the position data of the dual-antenna receiving terminal.

[0068] Figure 6 Figure 5. The positions of receiving antennas A and B obtained after 14 consecutive experiments. Pseudolites 1 and 2 are represented by black rectangles, the original positions of receiving antennas A and B are represented by black circles, and the solved positions of receiving antennas A and B are represented by green and red circles, respectively. The blue line connecting the red and green circles represents the corresponding antenna pair. Figure 7 The error statistics show that the error is generally between sub-meter and meter level. By changing the threshold of the optimization algorithm, the error can be further reduced. It can also be combined with inertial navigation. When the inertial navigation error exceeds a certain threshold, the carrier phase positioning method is used to reduce the cumulative error of inertial navigation and correct the positioning data to achieve the purpose of precise indoor positioning and navigation.

Claims

1. A positioning method for indoor dual-antenna reception based on carrier phase difference optimization, characterized by: The specific steps include: Step 1: Install two pseudo-satellites indoors. The two-dimensional position coordinates of pseudo-satellites 1 and 2 are S1 (X1, Y1) and S2 (X2, Y2) respectively. Install a dual-antenna receiving terminal on the device that needs to obtain positioning information. The dual-antenna receiving terminal includes receiving antennas A and B. The straight-line distance between receiving antennas A and B is is 0.5~1 carrier wavelength λ, and the position coordinates are recorded as (X a ,Y a )、(X b ,Y b ); Step 2: Before measuring the carrier phase, the carrier phase value θ from any pseudo-satellite to the receiving antennas A and B is a0 ,θ b0 , calculate the reference error θε=θ a0 -θ b0 ; Step 3: Calculate the carrier phase difference of the pseudolite received by antennas A and B at the same time, and correct it using the reference error. After correction, the carrier phase differences from pseudolite 1 and pseudolite 2 to antennas A and B are: △θ1 =(θ 1a -θ 1b -the) △θ2=(θ 2a -θ 2b -the) Among them, θ 1a ,θ 1b are the carrier phase data of receiving antennas A, B and pseudo-satellite 1, θ 2a ,θ 2b are the carrier phase data of receiving antennas A, B and pseudolite 2 respectively; Using the carrier phase difference, calculate the distance difference between pseudolite 1 and pseudolite 2 and receiving antennas A and B respectively 、 ; Step 4: The distance difference between the pseudo-satellite and different receiving antennas calculated in step 3 、 Import the objective function f(x,y) and add constraints to establish an optimization model that minimizes the residual between the measured carrier phase difference and the theoretically calculated carrier phase difference: Where Δd1 and Δd2 represent the theoretical distance differences from pseudolites 1 and 2 to the phase centers of receiving antennas A and B, respectively; Step 5: Solve the optimization model to obtain the location of the receiving terminal Select an optimization algorithm, give the initial coordinate values ​​of the receiving antennas A and B, and iterate the objective function established in step 4 multiple times. When the objective function value is minimized and less than the set threshold, output the iterative result as the position data of the dual-antenna receiving terminal to achieve indoor positioning.

2. The indoor dual-antenna positioning method based on carrier phase difference optimization solution as claimed in claim 1 is characterized in that: Signal coverage simulation software is used to simulate the signal coverage results of pseudolites installed in different positions, and the pseudolites position installation plan is determined based on the simulation results.

3. The indoor dual-antenna positioning method based on carrier phase difference optimization solution as claimed in claim 1 is characterized in that: The message sent by the pseudolite is in the GPS standard format, and includes the two-dimensional position of the pseudolite, the pseudolite number, the spread spectrum code number, the pseudolite signal status and the signal transmission time.

4. The indoor dual-antenna positioning method based on carrier phase difference optimization solution as claimed in claim 1, characterized in that: The straight-line distance between receiving antennas A and B It is 1 or less than 1 carrier wavelength λ.

5. The indoor dual-antenna positioning method based on carrier phase difference optimization solution as claimed in claim 1 is characterized in that: Set the constraints as: Among them, X min and X max They represent the minimum and maximum values ​​of the X axis of the indoor area after the coordinate axis is fixed; min and Y max They represent the minimum and maximum Y-axis values ​​of the indoor area after the coordinate axis is fixed.

6. The indoor dual-antenna positioning method based on carrier phase difference optimization solution as claimed in claim 1, characterized in that: The optimization algorithm selected is the sequential quadratic programming algorithm or the interior point method.

7. The indoor dual-antenna positioning method based on carrier phase difference optimization solution as claimed in claim 6, characterized in that: When the dual-antenna receiving terminal receives the pseudo-satellite signal for the first time, it is considered that the state of the point to be located is moving from outdoor to indoor, and the gate position or the last positioning position of the point to be located outdoors is selected as the initial coordinate value; when the point to be located moves indoors, the positioning result at the previous moment is selected as the initial coordinate value.

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