Indoor double-antenna receiving positioning method based on carrier phase difference optimization solution

Abstract

The invention discloses an indoor double-antenna receiving positioning method based on carrier phase difference optimization solution. The method comprises the following steps: firstly, installing two pseudo satellites indoors for sending signals and messages in a GPS standard format; a double-antenna receiving terminal is installed on a device needing to obtain positioning information. And then obtaining a carrier phase reference error from the receiving terminal to the pseudo-satellite. In the positioning process, a receiving terminal is used for receiving a pseudolite message signal, carrier phase differences between a pseudolite 1 and a pseudolite 2 and receiving antennas A and B are calculated according to carrier phase conditions, and distance differences between the pseudolite and the receiving antennas A and B are respectively calculated by using the carrier phase differences; and establishing an optimization model for minimizing the residual error between the measured carrier phase difference and the theoretically calculated carrier phase difference, and solving the position data of the double-antenna receiving terminal by using an optimization algorithm to realize indoor positioning.

Description

Technical Field

[0001] The invention belongs to the technical field of navigation and positioning, and in particular relates to a positioning method for indoor dual-antenna reception 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, and indoor positioning services have become a hot research direction. 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 to calculate the inverse pseudo-range, or by comparing the phase difference of the carrier and inverting to achieve high-precision positioning. The Global Navigation Satellite System (GNSS) performs well in outdoor high-precision positioning, but in indoor environments with complex environments, obvious signal attenuation, scattering and multipath effects, GNSS signals will be severely interfered. In order to achieve high-precision indoor positioning, researchers have proposed a variety of methods, including pseudo-satellite technology, WI-FI positioning, Bluetooth positioning, ultra-wideband (UWB) technology and other positioning methods.

[0003] However, although UWB positioning has high accuracy and good penetration of obstacles, it is difficult to achieve large-scale coverage and the positioning cost is high. Zigbee uses RSSI values ​​for positioning, which is highly secure and low power, but has high requirements for the algorithm and is difficult to achieve synchronous positioning in complex environments. Bluetooth positioning is widely used because of its small size, low power consumption, and easy integration into mobile terminals, but it is susceptible to electromagnetic interference and requires the deployment of a local area network, resulting in high costs. Geomagnetic positioning may encounter feature similarity problems indoors, which places high demands on the feature extraction ability and robustness of the algorithm.

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

[0005] In view of the shortcomings of the prior art, the present invention proposes a positioning method for indoor dual-antenna reception based on carrier phase difference optimization solution, arranges pseudo-satellites at reasonable positions indoors, provides reliable GNSS-like signals for indoor positioning, optimizes the configuration of the receiving terminal, and uses 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: Step 1: Install two pseudo-satellites indoors. The two-dimensional position coordinates of pseudo-satellites 1 and 2 are recorded as S1 (X1, Y1) and S2 (X2, Y2) respectively. The message sent by the pseudo-satellite is in the standard GPS format, including the two-dimensional position of the pseudo-satellite, pseudo-satellite number, spread spectrum code number, pseudo-satellite signal status and signal transmission time.

[0007] 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.

[0008] Preferably, signal coverage simulation software is used to simulate the signal coverage results of pseudo-satellites installed in different positions, and the pseudo-satellite position installation plan is determined according to the simulation results to reduce the impact of indoor shielding.

[0009] 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 pseudo-satellite. At this time, the distances from the pseudo-satellite to the receiving antennas A and B are equal. Theoretically, the carrier phase difference to the receiving antennas A and B should be 0. However, there will be errors in practice. 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 .

[0010] Step 3: The dual-antenna receiving terminal receives the positioning signal sent by the pseudo-satellite and demodulates the message, performs carrier phase measurement, calculates the carrier phase difference of the pseudo-satellite received by the receiving antennas A and B at the same time, and uses the reference error to correct it. After correction, the carrier phase differences from pseudo-satellite 1 and pseudo-satellite 2 to the receiving antennas A and B are: △θ1 =(θ 1a -θ 1b -θε) △θ2=(θ 2a -θ 2b -θε) Among them, θ 1a ,θ 1b are the carrier phase data of receiving antenna A, B and pseudo-satellite 1, θ 2a ,θ 2b They are the carrier phase data of receiving antennas A, B and pseudo-satellite 2 respectively.

[0011] Using the carrier phase difference, calculate the distance difference between pseudo-satellite 1 and pseudo-satellite 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 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 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: 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.

[0012] 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 to solve When the objective function value is minimized and is less than the set threshold, the iteration result is output as the position data of the dual-antenna receiving terminal to achieve indoor positioning.

[0013] Preferably, the selected optimization algorithm may be a Sequental Quadratic Programming Method (SQP) or an Interior Point Method.

[0014] Preferably, 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 entering indoors from outdoor, and the gate position or the last outdoor positioning position of the point to be located is selected as the initial value of the coordinates. When the point to be located moves indoors, the positioning result at the previous moment is selected as the initial value of the coordinates.

[0015] The present invention has the following beneficial effects: 1. High-precision positioning: By using carrier phase difference measurement and optimization solution, 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 easy to maintain.

[0016] 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.

[0017] 3. Application in various positioning scenarios: This method can be extended to multiple different scenarios such as industrial environments and warehouse management. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the positioning method of indoor dual-antenna reception based on carrier phase difference optimization solution; Figure 2 It is a schematic diagram of a field test in the embodiment; Figure 3 is the initial carrier phase reference error correction parameter; Figure 4 is the carrier phase difference value of pseudolite 1 in the embodiment; Figure 5 is the carrier phase difference value of pseudolite 2 in the embodiment; Figure 6 is a schematic diagram of multiple groups of positioning results obtained in the embodiment; Figure 7 It is a statistical diagram of errors of multiple groups of positioning results in the embodiment. DETAILED DESCRIPTION

[0019] The present invention is further explained below with reference to the accompanying drawings: like Figure 1 As shown in the figure, the positioning method of indoor dual-antenna reception based on carrier phase difference optimization solution uses indoor pseudo satellites and high-precision dual-antenna receiving terminals to collect measurement data such as carrier phase for calculation and optimization to achieve indoor positioning. The following describes the actual process of indoor positioning testing using this method.

[0020] 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 2As shown in the figure, the site size is about 800*1000 (cm). Two pseudo-satellites 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 pseudo-satellites 1 and 2 are (-100, 700) and (200, 700) respectively. The straight-line distance between receiving antennas A and B that needs to be solved is The distance between the pseudo satellite and the ground is 20 cm, and the position coordinates are (-10, 0) and (10, 0) respectively. The message sent by the pseudo satellite is in the standard format of GPS, and the carrier base frequency is 10.23Mhz, which is converted to L1 band 1575.42Mhz after up-conversion.

[0021] 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.

[0022] Step 3: The dual-antenna receiving terminal receives the message sent by the pseudo-satellite, demodulates it, and obtains the carrier phase. The output data format is NMEA format and CASIC format, and the data content includes: time information, carrier phase and pseudo-satellite position coordinates. The carrier phase and other information are stored in the CASIC protocol format information; find 0x03 0x10, that is, the RXM-MEASX field, which stores the measurement value information, and extract the carrier phase information of the receiving terminal from the payload.

[0023] The relationship between pseudorange ρ and carrier phase difference is: 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 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 integer ambiguity difference. 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 condition. Therefore, the carrier phase difference received by the receiving terminal can reflect the pseudorange difference information. When the position of the pseudosatellite coordinate point is known, the carrier phase information has a certain functional relationship with the position information of the receiving antenna:

[0024] This method calculates the carrier phase difference of pseudolites received by receiving 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 =-0.147. The carrier phase difference data of the two dual-antenna receiving terminals to pseudo-satellite 2 before correction is 0.2374. After eliminating the error is 0.2971. 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:

[0025] 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: 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 axis is fixed; f(x,y) is the objective function, which represents the measurement of the position error; △d1 and △d2 represent the theoretical distance difference from pseudo-satellite 1 and 2 to the phase center of receiving antenna A and B respectively: In this embodiment, according to the size of the indoor space, the iteration 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.

[0026] Step 5: Solve the optimization model to obtain the location of the receiving terminal This embodiment selects the sequential quadratic programming algorithm (SQP), given the initial coordinate values ​​of the receiving antennas A and B, and iterates the objective function established in step 4 multiple times. When the objective function value is minimized and less than the set threshold, the iterative result is output as the position data of the dual-antenna receiving terminal.

[0027] Figure 6 Figure 2 shows the positions of receiving antennas A and B 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, the calculated positions of receiving antennas A and B are represented by green circles and red circles, respectively, and the blue line connecting the red and green circles represents the corresponding antenna pairs. Figure 7 The error statistics show that the error is generally between sub-meter and meter level. The error can be further reduced by changing the threshold of the optimization algorithm. 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 solution, characterized in that: The specific steps include: Step 1: Install two pseudo-satellites indoors, and record the two-dimensional position coordinates of pseudo-satellites 1 and 2 as 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, and 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, according to the carrier phase value θ from any pseudo-satellite to the receiving antenna A or B a0 ,θ b0 , calculate the reference error θε=θ a0 -θ b0 ; Step 3: Calculate the carrier phase difference of the pseudolites received by receiving antennas A and B at the same time, and correct it using the reference error. After correction, the carrier phase differences from pseudolites 1 and 2 to receiving 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 antenna A, B and pseudo-satellite 1, θ 2a ,θ 2b are the carrier phase data of receiving antennas A, B and pseudo-satellite 2 respectively; Using the carrier phase difference, calculate the distance difference between pseudo-satellite 1 and pseudo-satellite 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: Wherein, 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 pseudo-satellites installed in different positions, and the pseudo-satellite 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 pseudo-satellite is in the standard GPS format, and its content includes the two-dimensional position of the pseudo-satellite, the pseudo-satellite number, the spread spectrum code number, the pseudo-satellite signal status and the signal transmission time.

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

5. The indoor dual-antenna reception 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 is characterized in that: The optimization algorithm selected is the sequential quadratic programming algorithm or the interior point method.

7. The indoor dual-antenna receiving positioning method based on carrier phase difference optimization solution as claimed in claim 6 is 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 entering indoors from outdoors, 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 of the previous moment is selected as the initial coordinate value.

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