Distributed mimo pseudolite system and method for pipe rack deformation monitoring

Abstract

The application provides a distributed MIMO pseudolite system and method for deformation monitoring of a pipe gallery, the system comprising a plurality of MIMO pseudolite base stations, each of which transmits a pseudolite signal in a TDM mode, and the deformation monitoring is realized by mutual positioning between each of the MIMO pseudolite base stations, and a topology structure is formed between the plurality of MIMO pseudolite base stations, and when deformation monitoring points of the pipe gallery change, the topology structure changes, thereby realizing deformation monitoring of the pipe gallery. The distributed MIMO pseudolite system is constructed, and networking positioning is realized by deploying the pseudolite base stations in the pipe gallery. The device makes the construction of the pseudolite positioning system more convenient and flexible, and can realize deformation monitoring of the pipe gallery.

Description

Technical Field

[0001] This invention relates to a distributed MIMO pseudo-satellite system and method for monitoring the deformation of utility tunnels, belonging to the fields of radio navigation and positioning technology and building deformation monitoring. Background Technology

[0002] Underground urban pipeline corridors are tunnel spaces constructed beneath cities to integrate various engineering pipelines such as electricity, communications, gas, heating, and water supply and drainage. They are equipped with dedicated maintenance ports, hoisting ports, and monitoring systems, and are subject to unified planning, design, construction, and management. They are vital infrastructure and "lifelines" ensuring urban operation. As people's quality of life continues to improve, protecting the stability of underground pipeline corridors and meeting people's daily needs becomes increasingly important. With the continuous improvement of positioning technology, various positioning technologies are constantly developing. Currently, in vast outdoor areas, technologies represented by Global Navigation Satellite Systems (GNSS) such as BeiDou and GPS are becoming increasingly sophisticated and can basically meet the corresponding positioning needs. However, in underground (tunnel) spaces, GNSS signals cannot reach the corresponding areas due to obstruction by walls and other objects. Therefore, pseudo-satellite technology has become one of the important methods to solve the positioning problem in underground (tunnel) spaces. Due to the similarity of signal systems, pseudo-satellite signals and GPS signals have good compatibility. However, due to the complexity of the underground space environment and the characteristics of numerous turns and relatively enclosed scenarios, simple pseudo-satellite systems can no longer meet the needs of high-precision and stable positioning services and therefore cannot provide deformation monitoring services.

[0003] MIMO pseudo-satellite signal systems are suitable for non-exposed spaces requiring positioning services, such as buildings, underground spaces, tunnels, and large indoor environments. They are particularly useful in areas with wide coverage and complex environments where satellite signals cannot be received. Integrated utility tunnels, distributed throughout cities, facilitate the daily inspection, repair, and maintenance of numerous facilities. To ensure the stability and safety of underground integrated utility tunnels, deformation monitoring is necessary to minimize safety hazards. Distributed MIMO pseudo-satellite systems enable multiple base stations to transmit and receive, resolving clock synchronization issues between base stations. Because a single base station can transmit and receive, the number of detection points in underground integrated utility tunnels can be increased, allowing for better deformation monitoring. While pseudo-satellite base station devices are one effective way to achieve global positioning, their hardware implementation is costly and complex. This paper describes a solution using the GNU Radio software radio platform and FPGA+AD9361 to generate, transmit, and receive pseudo-satellite signals, and to monitor and process the observed data to achieve deformation monitoring. Summary of the Invention

[0004] Technical issues: Most pseudo-satellite systems are single-transmitter and single-receiver systems that can only output radio frequency signals, which cannot meet the requirements of users who only need to use baseband signals or digital intermediate frequency signals. It is also inconvenient to process, analyze and test pseudo-satellite signals. In the environment of integrated utility tunnels, the obstruction of objects such as walls and pipes prevents GNSS signals from reaching the corresponding areas. There are many bends and the environment is relatively complex. Simple pseudo-satellite systems can no longer meet the needs of high-precision and stable positioning services and therefore cannot provide deformation monitoring services.

[0005] The distributed MIMO pseudosatellite system for deformation monitoring of integrated utility tunnels, as described in this invention, can generate multiple pseudosatellite signals. Through a shared antenna and a front-end RF chip, multi-channel time-division transmission can be performed, meeting the requirements of some users needing digital intermediate frequency signals. It can also receive multiple pseudosatellite signals. By acquiring pseudorange and carrier phase observations within the base station and using deformation monitoring algorithms to observe the coordinates of the measured points over a long period, deformation monitoring of multiple points in the utility tunnel can be achieved. This invention improves deformation monitoring efficiency by analyzing the geological vulnerability of specific underground integrated utility tunnels and deploying corresponding base stations.

[0006] Technical solution: The method of the present invention to solve the above-mentioned technical problems is achieved through the following technical solution:

[0007] This invention first provides a distributed MIMO pseudo-satellite system for monitoring the deformation of utility tunnels. The system includes multiple MIMO pseudo-satellite base stations. Each MIMO pseudo-satellite base station transmits pseudo-satellite signals via TDM. Multi-point deformation monitoring is achieved by mutual positioning between each MIMO pseudo-satellite base station. Multiple MIMO pseudo-satellite base stations form a topology. When deformation occurs at a monitoring point in the utility tunnel, the topology changes, thereby realizing the deformation monitoring of the utility tunnel.

[0008] Furthermore, each MIMO pseudo-satellite base station includes an n-channel pseudo-satellite transmitting module, a baseband signal generating module, an n-channel pseudo-satellite receiving module, a baseband signal processing module, and n sets of shared antennas;

[0009] The n-channel pseudo-satellite receiver module receives signals from MIMO pseudo-satellite base stations or other MIMO pseudo-satellite base stations through n sets of shared antennas, demodulates them to generate n digital intermediate frequency pseudo-satellite signals, and outputs them to the baseband signal processing module.

[0010] The baseband signal generation module generates n modulated digital intermediate frequency pseudo-satellite signals, which are then output to the n-channel pseudo-satellite transmission module and broadcast in a time-division multiplexing manner through n shared antennas.

[0011] Furthermore, the n-channel pseudo-satellite launch module includes n transmission channels in the radio frequency front-end chip;

[0012] The baseband signal generation module includes a pseudo-satellite navigation message generation module, a C / A code generation module, an intermediate frequency carrier generation module, a spreading code generation module, and a BPSK modulation module;

[0013] The RF front-end chip has n transmit channels that perform up-conversion and digital-to-analog conversion on n pseudo-satellite digital intermediate frequency signals to generate n high-frequency analog pseudo-satellite signals. The n high-frequency analog pseudo-satellite signals are then output to n shared antennas. By controlling the antenna switches, the n shared antennas receive the high-frequency analog pseudo-satellite signals and then broadcast them, thus realizing the transmission of the base station signal.

[0014] Furthermore, the n-channel pseudo-satellite receiving module includes n receiving channels in the radio frequency front-end chip, and n shared antennas are deployed in different locations. By controlling the antenna switches, when receiving signals from other channels of the base station within the pseudo-satellite system or signals from other pseudo-satellite base stations, the received pseudo-satellite signals are output to the radio frequency front-end chip. After receiving the high-frequency pseudo-satellite analog signals, the radio frequency front-end chip performs down-conversion and analog-to-digital conversion to generate n digital intermediate frequency pseudo-satellite signals, which are then output to the baseband signal processing module.

[0015] The present invention also provides a method for monitoring the deformation of utility tunnels using the aforementioned distributed MIMO pseudo-satellite system, the method comprising the following steps:

[0016] S1: Within the measurement space of the tunnel to be monitored, a MIMO pseudo-satellite base station is deployed at intervals D. Multiple shared antennas within each MIMO pseudo-satellite base station are deployed along the longitudinal section of the tunnel. Each MIMO pseudo-satellite base station selects one shared antenna point as a standard point, and the standard points of three adjacent MIMO pseudo-satellite base stations are ensured to be non-collinear. Assume the coordinates of the measurement point are (X... i ,Y i Z i The coordinates of multiple standard points are (x... j ,y j ,z j The approximate three-dimensional coordinates of the measurement point and the standard point, and their respective corrections are as follows: (δX i ,δY i ,δZ i ), (δx j ,δy j ,δz j );

[0017] S2: The distance measured from the i-th measuring point to the j-th standard point is S. ij The ranging value can be determined by the pseudorange and carrier phase values ​​in the baseband signal processing module:

[0018]

[0019] Linearizing equation (9) yields the error equation:

[0020] v ij =a ij δX i +b ij δY i +c ij δZ i -a ij δx j -b ij δy j -c ij δz j -l ij (2)

[0021] Where the coefficient a ij b ij c ij With constant l ij It is obtained by calculation using the following formula:

[0022]

[0023]

[0024]

[0025]

[0026] l ij This represents the difference between the measured distance and the approximate value between the i-th measurement point and the j-th standard point;

[0027] Applying equation (3) to m measurement points and q standard points within the measurement space, and establishing the error equation in matrix form, we have:

[0028] V=AδX-l (3)

[0029] Where V is the residual vector, δX is the unknown parameter, A is the coefficient matrix of the unknown parameter, l is the distance difference constant, and A T It is the transpose of the coefficient matrix;

[0030] The normal equation is as follows:

[0031] A T PAδX=A T Pl (4)

[0032] Using the rank-deficient network adjustment formula, the coordinates of each point are calculated according to the normal equation, and the error is analyzed as follows:

[0033]

[0034] Where P is the weight matrix, N is the normal equation coefficient matrix, G is the centroid datum constraint matrix, δX is the unknown parameter, and Q is the unknown parameter. δx It is a cofactor matrix;

[0035] The coordinates of each measurement point and standard point are stored every 30 minutes and continuously observed for 24 hours. When the coordinate values ​​of each point change significantly, the integrated utility tunnel will deform.

[0036] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0037] The MIMO pseudosatellite signal system proposed in this invention solves the problems of high hardware cost of pseudosatellites and the fact that they can only output radio frequency signals, which cannot meet the requirements of users who only need to use baseband signals or digital intermediate frequency signals. The distributed MIMO pseudosatellite system can transmit and receive multiple signals, realize the networking requirements of a single constellation in a small area, realize communication between multiple constellations, and meet the needs of providing high-precision positioning services over a large area during long-term detection, thus enabling deformation monitoring. Attached Figure Description

[0038] Figure 1 : Deployment diagram of the distributed MIMO pseudo-satellite system for monitoring pipe gallery deformation according to the present invention;

[0039] Figure 2 : A schematic diagram of the structure of each MIMO pseudo-satellite base station of the present invention;

[0040] Figure 3 Flowchart of the method for monitoring pipe gallery deformation according to the present invention;

[0041] Figure 4 : Long-term deformation monitoring results of the present invention. Detailed Implementation

[0042] The implementation process of the present invention will be described in detail below with reference to the embodiments and the accompanying drawings.

[0043] Example 1: MIMO Pseudo-satellite System

[0044] The MIMO pseudo-satellite base station includes an n-channel pseudo-satellite transmitting module, a baseband signal generating module, an n-channel pseudo-satellite receiving module, a baseband signal processing module, and n sets of shared antennas;

[0045] The n-channel pseudo-satellite receiver module receives signals from within or from other MIMO pseudo-satellite base stations by controlling the antenna switches of n shared antennas, demodulates them to generate n digital intermediate frequency pseudo-satellite signals, and outputs them to the baseband signal processing module.

[0046] The baseband signal generation module generates n modulated digital intermediate frequency pseudo-satellite signals, which are then output to the n-channel pseudo-satellite transmission module and broadcast in a time-division manner by controlling the antenna switches of n shared antennas.

[0047] The generation of pseudo-satellite signals includes

[0048] (1) Obtaining the baseband signal of the pseudo-satellite analog signal according to the navigation message parameters, including: C / A code generation, generating navigation message according to the navigation message parameters;

[0049] (2) Obtain the spreading code data stream of the pseudo-satellite analog signal based on the navigation message and the spreading code;

[0050] (3) The baseband signal is modulated by BPSK and then by intermediate frequency carrier modulation to obtain the digital intermediate frequency signal of the satellite analog signal.

[0051] (4) Pseudo-satellite signal simulation generation process

[0052] The pseudo-satellite signal is composed of "ranging code + navigation message" modulated on a carrier wave. The standard signal representation of pseudo-satellite p is s. (p) (t), whose signal expression is as follows:

[0053] s (p) (t)=A p D p (t)C p (t)cos(2πf c t) (6)

[0054] In the formula, p represents the pseudo-satellite PRN number, A represents the pseudo-satellite signal amplitude, D(t) is the navigation message data, C(t) is the ranging code data, and f c f is the frequency of the pseudo-satellite signal. IF Given the intermediate frequency signal frequency, its up-conversion frequency relationship is as follows:

[0055] In the actual simulation process, the simulated data of the pseudo-satellite standard signal generated by the pseudo-satellite signal generation unit is its discrete sampled signal x. (p) [k], the relationship is:

[0056]

[0057] Where p represents the pseudo-satellite PRN number, the simulated discrete sampling signal x[k], and the intermediate frequency signal s IF (t), T s This represents the sampling time, and k represents the sampling point.

[0058] Among them, pseudo-satellite ranging observations were obtained, including

[0059] (1) The pseudo-satellite is captured and tracked. The corresponding Doppler frequency shift and pseudo-code phase are demodulated to obtain the accurate values. Then the carrier and pseudo-random code are separated from the intermediate frequency signal to obtain the baseband signal.

[0060] (2) By storing various observations or performing PVT calculations, it is possible to obtain distance measurement values ​​and positioning functions.

[0061]

[0062]

[0063] In the above formula, r and s represent the receiver and the pseudo-satellite, respectively; and These represent the pseudorange and carrier phase observations of receiver r on pseudosatellite s, respectively. Δt represents the geometric distance between the receiver r and the pseudo-satellite s; c represents the propagation speed of the radio signal; Δt r and Δt s d represents the clock bias of the receiver and the pseudo-satellite, respectively; r and d s λ represents the error caused by receiver and pseudosatellite hardware delays, respectively; s This represents the carrier wavelength of the signal transmitted by pseudosatellite s; This represents the integer ambiguity between the receiver r and the pseudo-satellite s; and These represent the sum of various errors in the process of solving for pseudorange and carrier phase observations, respectively.

[0064] Example 2: Deployment of Distributed MIMO Base Stations

[0065] Base stations are deployed on a longitudinal section of an underground utility tunnel. Through geological vulnerability analysis, it can be selected whether to uniformly deploy shared antennas on the longitudinal section. Base stations are then deployed again on the longitudinal section of the utility tunnel at a distance D apart. Multiple base stations can detect each other. Through positioning monitoring algorithms, long-term 24-hour monitoring is performed to form a relatively stable detection topology. If the position of a point changes significantly, deformation occurs. Deformation monitoring is performed by analyzing carrier phase observations and measurement point coordinates.

[0066] Example 3: Localization Detection Algorithm

[0067] S1: Within the measurement space of the tunnel to be monitored, a MIMO pseudo-satellite base station is deployed at intervals D. Multiple shared antennas within each MIMO pseudo-satellite base station are deployed along the longitudinal section of the tunnel. Each MIMO pseudo-satellite base station selects one shared antenna point as a standard point, and the standard points of three adjacent MIMO pseudo-satellite base stations are ensured to be non-collinear. Assume the coordinates of the measurement point are (X...i ,Y i Z i The coordinates of multiple standard points are (x... j ,y j ,z j The approximate three-dimensional coordinates of the measurement point and the standard point, and their respective corrections are as follows: (δX i ,δY i ,δZ i ), (δx j ,δy j ,δz j );

[0068] S2: The distance measured from the i-th measuring point to the j-th standard point is S. ij The ranging value can be determined by the pseudorange and carrier phase values ​​in the baseband signal processing module:

[0069]

[0070] Linearizing equation (9) yields the error equation:

[0071] v ij =a ij δX i +b ij δY i +c ij δZ i -a ij δx j -b ij δy j -c ij δz j -l ij (2)

[0072] Where the coefficient a ij b ij c ij With constant l ij

[0073]

[0074]

[0075]

[0076]

[0077] l ij This represents the difference between the measured distance and the approximate value between the i-th measurement point and the j-th standard point;

[0078] Applying equation (3) to m measurement points and q standard points within the measurement space, and establishing the error equation in matrix form, we have:

[0079] V=AδX-l (3)

[0080] Where V is the residual vector, δX is the unknown parameter, A is the coefficient matrix of the unknown parameter, l is the distance difference constant, and A T It is the transpose of the coefficient matrix;

[0081] The normal equation is as follows:

[0082] A T PAδX=A T Pl (4)

[0083] Using the rank-deficient network adjustment formula, the coordinates of each point are calculated according to the normal equation, and the error is analyzed as follows:

[0084]

[0085] Where P is the weight matrix, N is the normal equation coefficient matrix, G is the centroid datum constraint matrix, δX is the unknown parameter, and Q is the unknown parameter. δx It is a cofactor matrix;

[0086] The coordinates of each measurement point and standard point are stored every 30 minutes and continuously observed for 24 hours. When the coordinate values ​​of each point change significantly, the integrated utility tunnel will deform.

[0087] Figure 4 This is a result image of long-term deformation monitoring, from Figure 4 It can be seen that the long-term cumulative horizontal displacement of the monitoring points can be observed in the long-term simulation data, which can meet the requirements of deformation monitoring.

[0088] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A distributed MIMO pseudosatellite system for monitoring pipe gallery deformation, characterized in that, The system includes multiple MIMO pseudo-satellite base stations. Each MIMO pseudo-satellite base station transmits pseudo-satellite signals via TDM. Multi-point deformation monitoring is achieved by mutual positioning between each MIMO pseudo-satellite base station. Multiple MIMO pseudo-satellite base stations form a topology. When deformation occurs at a monitoring point in the integrated utility tunnel, the topology changes, thus enabling deformation monitoring of the utility tunnel. The method for monitoring pipe gallery deformation using a distributed MIMO pseudosatellite system includes the following steps: S1: Within the measurement space of the tunnel to be monitored, a MIMO pseudo-satellite base station is deployed at intervals D. Multiple shared antennas within each MIMO pseudo-satellite base station are deployed along the longitudinal section of the tunnel. Each MIMO pseudo-satellite base station selects one shared antenna point as a standard point, and the standard points of three adjacent MIMO pseudo-satellite base stations are ensured to be non-collinear. Assume the coordinates of the measurement point are... The coordinates of multiple standard points are The approximate three-dimensional coordinates of the measurement point and the standard point, and their respective corrections are as follows: ; S2: The distance measured from the i-th measuring point to the j-th standard point is... The ranging value can be determined by the pseudorange and carrier phase values ​​in the baseband signal processing module: （1） Linearizing equation (9) yields the error equation: （2） Where the coefficient With constant It is obtained by calculation using the following formula: This represents the difference between the measured distance and the approximate value between the i-th measurement point and the j-th standard point; Applying equation (3) to m measurement points and q standard points within the measurement space, and establishing the error equation in matrix form, we have: （3） in For the residual vector, For unknown parameters, The coefficient matrix contains unknown parameters. The distance difference is a constant. It is the transpose of the coefficient matrix; The normal equation is as follows: （4） Using the rank-deficient network adjustment formula, the coordinates of each point are calculated according to the normal equation, and the error is analyzed as follows: （5） in Let N be the weight matrix and N be the coefficient matrix of the normal equation. The barycentric reference constraint matrix, For unknown parameters, It is a cofactor matrix; The coordinates of each measurement point and standard point are stored every 30 minutes and continuously observed for 24 hours. When the coordinate values ​​of each point change significantly, the integrated utility tunnel will deform.

2. The distributed MIMO pseudo-satellite system for monitoring pipe gallery deformation according to claim 1, characterized in that, Each MIMO pseudo-satellite base station includes an n-channel pseudo-satellite transmitting module, a baseband signal generating module, an n-channel pseudo-satellite receiving module, a baseband signal processing module, and n sets of shared antennas; The n-channel pseudo-satellite receiver module receives signals from MIMO pseudo-satellite base stations or other MIMO pseudo-satellite base stations through n sets of shared antennas, demodulates them to generate n digital intermediate frequency pseudo-satellite signals, and outputs them to the baseband signal processing module. The baseband signal generation module generates n modulated digital intermediate frequency pseudo-satellite signals, which are then output to the n-channel pseudo-satellite transmission module and broadcast in a time-division multiplexing manner through n shared antennas.

3. The distributed MIMO pseudo-satellite system for monitoring pipe gallery deformation according to claim 2, characterized in that, The n-channel pseudo-satellite launch module includes n launch channels in the radio frequency front-end chip; The baseband signal generation module includes a pseudo-satellite navigation message generation module, a C / A code generation module, an intermediate frequency carrier generation module, a spreading code generation module, and a BPSK modulation module; The RF front-end chip has n transmit channels that perform up-conversion and digital-to-analog conversion on n pseudo-satellite digital intermediate frequency signals to generate n high-frequency analog pseudo-satellite signals. The n high-frequency analog pseudo-satellite signals are then output to n shared antennas. By controlling the antenna switches, the n shared antennas receive the high-frequency analog pseudo-satellite signals and then broadcast them, thus realizing the transmission of the base station signal.

4. The distributed MIMO pseudo-satellite system for monitoring pipe gallery deformation according to claim 2, characterized in that, The n-channel pseudo-satellite receiving module includes n receiving channels in the radio frequency front-end chip and n shared antennas deployed at different locations. By controlling the antenna switches, when receiving signals from other channels of the base station within the pseudo-satellite system or signals from other pseudo-satellite base stations, the received pseudo-satellite signals are output to the radio frequency front-end chip. After receiving the high-frequency pseudo-satellite analog signals, the radio frequency front-end chip performs down-conversion and analog-to-digital conversion to generate n digital intermediate frequency pseudo-satellite signals, which are then output to the baseband signal processing module.

Images