A Method and System for Deformation Monitoring of a Sluice in a Semi-occluded Environment

Abstract

The present invention discloses a method and system for sluice deformation monitoring in a semi-occluded environment. By using GNSS differential data and combining four frequency points of the Beidou-3 satellite to construct two groups of ultra-wide-lane combinations, the fixed solutions of the ultra-wide-lane and wide-lane ambiguities are solved. An ionosphere-free combination is formed by the fundamental frequencies B1I and B3I to obtain the floating solution of the ionosphere-free combination ambiguity. The floating solution of the ionosphere-free combination ambiguity is smoothed through Kalman filtering, and then combined and transformed with the fixed solution of the wide-lane ambiguity to obtain the floating solution of the ambiguity at the B1I frequency point. The ambiguity search is carried out through the LAMBDA algorithm to obtain the fixed solution of the ambiguity at the B1I frequency point. The fixed solutions of the ultra-wide-lane, wide-lane, and B1I ambiguities are combined to obtain the fixed solutions of the ambiguities at the other three frequency points. Finally, the double-difference ambiguity fixed solutions at each frequency point are substituted back to obtain the coordinate change amount of the monitoring point. When the deformation amount exceeds the preset threshold, it is determined that serious deformation has occurred at the monitoring point. The present invention can be applied to the sluice environment and has good positioning effects and broad application scenarios.

Description

Technical Field

[0001] The present invention belongs to the technical field of building monitoring based on satellite positioning and navigation technology, and particularly relates to a method and system for monitoring the deformation of a sluice under a semi-occluded environment. Background Art

[0002] With the utilization and protection of natural resources in China, the construction of water conservancy facilities to mitigate floods and droughts has attracted attention. Water conservancy facilities regulate, develop, utilize, and protect natural water resources to meet the needs of humans and the natural environment. At present, more than 100,000 sluices with a flow rate of more than 5 cubic meters per second and more than 300,000 kilometers of river dikes have been built in China. In the deformation monitoring of sluices, currently, manual observation methods such as vertical displacement observation and piezometric tube water level observation are used, which are greatly affected by observation environments such as darkness and visibility. In addition, the degree of automation is poor, and it is difficult to monitor in real time. When a dangerous situation occurs, it is difficult to detect in time, posing a great potential safety hazard.

[0003] With the full completion of China's Beidou navigation system, the number of Beidou satellites in orbit in China has reached 55 at present, which indicates that using Beidou for high-precision positioning in a sheltered environment has significant advantages compared with other navigation systems. However, in practical applications, relatively high buildings are usually built on sluices to lift the sluice gates, which will cause the monitoring points of the sluice to be severely blocked by the environment, resulting in a significant reduction in the number of available satellites. As a result, the number of Beidou satellite data observed by the monitoring station is small, the geometric structure of the satellite distribution is poor, and the quality of Beidou satellite data is reduced due to the influence of occlusion. At the same time, the monitoring points of the sluice are usually relatively close to the river surface, and the Beidou satellite data is also severely affected by multipath due to the influence of water surface reflection. Moreover, different from buildings such as bridges, the deformation process of sluices is relatively slow, so higher requirements are imposed on the accuracy and precision of satellite positioning. Summary of the Invention

[0004] To solve the problems of the existing technology that the number of observed satellites is small, the observed data is severely affected by multipath, and the data quality is reduced for the sluice monitoring points in a semi-occluded environment (within the range of horizontal 0 - 180 degrees and altitude angle 0 - 80 degrees), the present invention provides a method for monitoring the deformation of a sluice under a semi-occluded environment, which can realize real-time and accurate deformation monitoring of the sluice facilities. Further, the present invention also provides a monitoring system corresponding to this method.

[0005] The first aspect of the present invention discloses a method for monitoring the deformation of a sluice under a semi-occluded environment, mainly including the following steps:

[0006] S001: Select the four frequencies of B1I, B2a, B3I, and B1C in the Beidou-3 satellites from the received GNSS observation data X1 of the reference station and the GNSS observation data X2 obtained by the monitoring station itself as the basic frequencies, and use the carrier phase observations and pseudorange observations of the basic frequencies to construct basic frequency double-difference observation equations, obtaining the double-difference carrier phase observations and double-difference pseudorange observations of the basic frequencies;

[0007] S002: Use the double-difference carrier phase observations and double-difference pseudorange observations of the basic frequencies, combine them according to different coefficients, construct two groups of geometry-free and ionosphere-free ultra-wide-lane combinations, and obtain the float solutions of the ultra-wide-lane combination ambiguities;

[0008] S003: Filter the ultra-wide-lane combination ambiguities to obtain the smoothed float solutions of the ultra-wide-lane combination ambiguities;

[0009] S004: Round and fix the smoothed float solutions of the ultra-wide-lane combination ambiguities to obtain the fixed solutions of the ultra-wide-lane combination ambiguities;

[0010] S005: Use the double-difference carrier phase observations of the basic frequencies B1I and B3I to construct an ionosphere-free wide-lane combination, and then combine the fixed solutions of the ultra-wide-lane combination ambiguities with the double-difference carrier phase observations and the double-difference carrier phase observations of the wide-lane combination to obtain the float solutions of the wide-lane combination ambiguities;

[0011] S006: Filter the wide-lane combination ambiguities, and then round and fix the float solutions of the wide-lane combination ambiguities after filtering and smoothing to obtain the fixed solutions of the wide-lane combination ambiguities;

[0012] S007: Use the double-difference carrier phase observations and double-difference pseudorange observations of the basic frequencies B1I and B3I to construct an ionosphere-free combination, and obtain the double-difference carrier phase observations, double-difference pseudorange observations, and double-difference float solutions of the ambiguities of the ionosphere-free combination;

[0013] S008: Use the Kalman filter equation to filter the ambiguities of the ionosphere-free combination to obtain the double-difference float solutions of the ambiguities of the ionosphere-free combination that weaken the influence of the zenith tropospheric wet delay and the influence of the observation noise;

[0014] S009: Calculate the double-difference float solutions of the ambiguities of the basic frequency B1I based on the filtered and smoothed double-difference float solutions of the ambiguities of the ionosphere-free combination and the fixed solutions of the wide-lane combination ambiguities;

[0015] S010: Construct the ambiguity matrix Q and the ambiguity matrix X related to the double-difference ambiguities of the basic frequency B1I, and search the double-difference float solutions of the ambiguities of the basic frequency B1I through the LAMBDA algorithm to obtain the fixed solutions of the double-difference ambiguities of the basic frequency B1I;

[0016] S011: For the GNSS observation data collected continuously for several days, based on the zero-mean hypothesis, obtain the single-difference residual sequence of the carrier observation value of the fundamental frequency B1I, and then extract the low-frequency component in the single-difference residual sequence based on wavelet analysis;

[0017] S012: For the fundamental frequency B1I, construct a hemispherical multipath error model of the fundamental frequency B1I based on the minimum elevation angle latitude and the minimum azimuth angle longitude;

[0018] S013: In subsequent monitoring, first execute step S001 to construct the double-difference observation equation, then use the hemispherical multipath error model to weaken the multipath error of the double-difference carrier observation value of the fundamental frequency B1I, and then execute steps S002 - S0010 to solve the fixed solution of the double-difference ambiguity of the fundamental frequency B1I;

[0019] S014: Combine the fixed solution of the ultra-wide lane combination ambiguity, the fixed solution of the wide lane combination ambiguity and the fixed solution of the double-difference ambiguity of the fundamental frequency B1I, and respectively obtain the fixed solutions of the double-difference ambiguities of the fundamental frequencies B2a, B3I and B1C;

[0020] S015: Substitute back the fixed solutions of the double-difference ambiguities of the fundamental frequencies B1I, B2a, B3I, B1C to obtain the coordinate change amount of the monitoring point. When the deformation amount of the monitoring point exceeds the preset threshold, it is determined that the monitoring point has serious deformation.

[0021] The second aspect of the present invention discloses a lock deformation monitoring system in a semi-occluded environment, which mainly includes Beidou-3 satellites, a reference station and a monitoring station; wherein, the reference station is used to receive GNSS observation data and navigation ephemeris data and send them to the monitoring station; the monitoring station is used to receive the GNSS observation data and navigation ephemeris data sent by the reference station, and execute the lock deformation monitoring method in the semi-occluded environment described in the first aspect of the present invention.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention utilizes the multi-frequency characteristics of Beidou-3 satellites to construct an ionosphere-free and geometry-free ultra-wide lane combination and an ionosphere-free wide lane combination, and can obtain the fixed solution of the ultra-wide lane double-difference ambiguity in a single epoch, and then fix the wide lane double-difference ambiguity in a single epoch through the fixed solution of the ultra-wide lane ambiguity. The present invention uses the ultra-wide lane and wide lane technology to accurately fix the ambiguity in a single epoch, avoiding the problem that it is difficult to quickly fix the ambiguity due to serious influence of the environment and errors in the conventional method.

[0024] (2) The present invention uses the half - sphere multipath error model constructed in the early stage to weaken the multipath error of the fundamental frequency ambiguity Δ▽N1. After being fixed through LAMBDA search, the fixed solution of the fundamental frequency ambiguity Δ▽N1 is obtained. By combining the fixed solution of the fundamental frequency ambiguity Δ▽N1 with the fixed solutions of the ambiguities of the ultra - wide - lane and wide - lane combinations, the fixed solutions of the ambiguities of each fundamental frequency B1I, B2a, B3I, B1C are obtained. Thus, the relatively serious multipath error in the sluice environment can be greatly weakened. Its advantages are that on the one hand, it can improve the fixing efficiency of the ambiguity, and on the other hand, it can avoid incorrect ambiguity fixing, improving the positioning accuracy and precision.

[0025] (3) The present invention can be applied to the sluice environment, having good positioning effects and broad application scenarios. Description of the Drawings

[0026] Figure 1 Schematic diagram of the number of satellites observed by a certain sluice reference station;

[0027] Figure 2 Schematic diagram of the number of satellites observed by a certain sluice monitoring point;

[0028] Figure 3 Schematic diagram of the half - sphere multipath error model. Detailed Embodiment

[0029] Term Explanation:

[0030] Ionosphere - free and geometry - free ultra - wide - lane combination, abbreviation: ultra - wide - lane combination

[0031] Ionosphere - free wide - lane combination, abbreviation: wide - lane combination

[0032] Ultra - wide - lane double - difference ambiguity, abbreviation: ultra - wide - lane ambiguity

[0033] Wide - lane double - difference ambiguity, abbreviation: wide - lane ambiguity

[0034] Ionosphere - free combination double - difference ambiguity, abbreviation: ionosphere - free combination ambiguity

[0035] Half - sphere multipath error model, abbreviation: half - sphere model

[0036] The present invention applies the method of eliminating multipath error of the half - sphere model to the monitoring environment composed of Beidou satellites, reference stations, and monitoring stations. In the sluice environment, the reference station is usually built on the ground within 5 km near the sluice, with an open environment and stable foundation settlement. The satellites observed by the reference station are as Figure 1 shown. The reference station is used to receive GNSS observation data and navigation ephemeris and send them to the monitoring station. The monitoring station is usually built on the pier of the sluice. Due to the obstruction of the relatively high buildings on the sluice, it is difficult for the monitoring station to observe the satellites within the horizontal range of 0 - 180 degrees and the elevation angle range of 0 - 80 degrees. The satellites it observes are asFigure 2 As shown, the monitoring station is used to receive the GNSS observation data and navigation ephemeris data sent by the base station, and perform data differential processing with the GNSS observation data obtained by the monitoring station itself to obtain differential data.

[0037] The present invention uses GNSS differential data in combination with four frequency points of BeiDou-3 satellite B1I, B2a, B3I and B1C to construct two groups of ultra-wide lane combinations, solves the ultra-wide lane combination ambiguity fixed solution, and then uses the ultra-wide lane ambiguity fixed solution to fix the wide lane ambiguity; an ionosphere-free combination is formed by base frequencies B1I and B3I, and combined with the fixed wide lane ambiguity, an ionosphere-free combination ambiguity floating point solution is obtained; the ionosphere-free combination ambiguity floating point solution is smoothed by Kalman filtering to obtain a smoothed ionosphere-free combination floating point solution; the ionosphere-free combination ambiguity floating point solution and the wide lane ambiguity fixed solution are combined and transformed to obtain a single-frequency ambiguity floating point solution of the B1I frequency point; and then an ambiguity search is performed by a LAMBDA algorithm to obtain an ambiguity fixed solution of the B1I frequency point; at this time, the fixed solutions of the ultra-wide lane, wide lane and B1I ambiguities can be combined to obtain the ambiguity fixed solutions of the other three frequency points of the BeiDou-3 satellite. Then, the double-difference ambiguity fixed solution of each frequency point is back-substituted to obtain the change in the coordinates of the monitoring point. When the deformation of the monitoring point exceeds the preset threshold, it is determined that the monitoring point has been severely deformed.

[0038] The present invention uses a semi-spherical model to model multipath errors, and its main process is: using the ambiguity fixing solution of the B1I frequency point of the BeiDou-3 satellite, based on the "zero mean assumption", a single difference residual sequence of each frequency point of each satellite is obtained; then based on the wavelet analysis technology, the high-frequency component in the single difference residual is eliminated to obtain the single difference residual low-frequency component; then based on the satellite's repetition period, the semi-spherical model is used to model the multipath errors; subsequently, the constructed semi-spherical model is used to eliminate the multipath errors of the above four frequency points, thereby improving the fixing effect of the ambiguity, avoiding the problem of ambiguity fixing errors or failure to fix due to multipath error factors, and then achieving high-precision positioning in a short time.

[0039] Next, the present invention will be further explained in conjunction with the accompanying drawings and specific embodiments.

[0040] Example 1 discloses a method for monitoring deformation of a sluice gate in a semi-shaded environment, which mainly includes the following steps:

[0041] S001: The monitoring station selects the four frequency points B1I, B2a, B3I, and B1C of the BeiDou-3 satellite as the base frequency from the GNSS observation data X1 received from the reference station and the GNSS observation data X2 obtained by the monitoring station itself, constitutes the GNSS differential data, constructs the base frequency double-difference observation equation, and thereby obtains the double-difference carrier observation value and the double-difference pseudorange observation value of the base frequency.

[0042] Among them, the reference station is built within 5 km of the sluice, with good observation conditions and stable foundation settlement; the monitoring station is installed on the monitored object. Select the BeiDou-3 satellites (excluding geostationary orbit satellites) in the observed data X1 and X2, and use the carrier observations and pseudorange observations of the four frequency points B1I, B2a, B3I, and B1C of the BeiDou-3 satellites to construct double-difference carrier observation equations and double-difference pseudorange observation equations, as follows:

[0043]

[0044] In the formula, i and j are satellite identifiers, b is the reference station identifier, and r is the monitoring station identifier. is the double-difference carrier observation value. is the double-difference pseudorange observation value. is the double-difference geometric station-satellite distance. is the double-difference ionospheric delay. is the double-difference tropospheric delay. is the double-difference ambiguity. is the double-difference multipath error. are the double-difference carrier observation noise and double-difference pseudorange observation noise respectively.

[0045] It should be noted that the "double-difference" here refers to taking the difference between the reference station and the monitoring station, and taking the difference between the reference satellite and the non-reference satellite. The reference satellite is a satellite with relatively good conditions selected, and all other BeiDou-3 satellites are differenced with this satellite. The reference satellite is equivalent to a reference satellite.

[0046] S002: Use the double-difference carrier observation values and double-difference pseudorange observation values of the basic frequencies B1I, B2a, B3I, and B1C obtained in S001, combine them according to different coefficients, construct two groups of ultra-wide-lane combinations, and obtain the floating-point solution of the ultra-wide-lane combination ambiguity.

[0047] It should be noted that the main advantages of using the ultra-wide-lane combination are as follows: using the combination to eliminate error terms such as geometric station-satellite distance, tropospheric delay, and ionospheric delay, and at the same time, the characteristic of the relatively long wavelength of the ultra-wide-lane combination can resist the influence of a part of the multipath error.

[0048] The two groups of ultra-wide-lane combinations are E1(-1, 0, 0, 1) and E2(0, -1, 1, 0) respectively, and the combined observation equations are as follows:

[0049]

[0050] In the formula, i and j are satellite identifiers, b is the reference station identifier, and r is the monitoring station identifier. is the combined double-difference carrier observation value, η (m,n,p,q) and η (a',b',c',d') are the combined ionospheric amplification factors, λ (m,n,p,q)is the combined carrier wavelength, and are the combined carrier observation noise and the combined pseudorange observation noise respectively, is the combined double-difference pseudorange observation value, and f1, f2, f3, f4 correspond to the carriers

[0051] B1I, B2a, B3I, B1C frequencies, correspond to the double-difference carrier observation values of carriers B1I, B2a, B3I, B1C respectively, correspond to the double-difference pseudorange observation values of carriers B1I, B2a, B3I, B1C respectively.

[0052] Among them, the combination coefficients in combination E1 are: m = -1, n = 0, p = 0, q = 1; the combination coefficients in combination E2 are: m = 0, n = -1, p = 1, q = 0; a', b', c', d' are the combination coefficients of the double-difference pseudorange observation equation to be solved related to m, n, p, q. Through the above combined observation equations, a'+b'+c'+d' = 1, η (m,n,p,q) +η (a',b',c',d') = 0, which can eliminate geometric term errors such as tropospheric delay and errors such as ionospheric delay.

[0053] To minimize the noise, it is also necessary to satisfy The values of a', b', c', d' can be obtained by the minimum norm method.

[0054] Then the float solution of the ultra-wide lane combination ambiguity can be obtained through formula (7), and the expression of the float solution of the ultra-wide lane combination ambiguity is as follows:

[0055]

[0056] It can be seen that the ultra-wide lane ambiguity is only affected by the carrier observation noise and the pseudorange observation noise. The wavelength of combination E1 is about 21 meters, and the wavelength of combination E2 is about 3.2 meters. According to experience, more than 99.9% of the influence of the carrier observation noise and the pseudorange observation noise on the combined wavelength is within 0.2 cycles. Therefore, the ambiguity can be fixed by taking the integer in a single epoch.

[0057] S003: To improve the fixing effect, Hatch filtering can be used to smooth the ultra-wide lane combination ambiguity and weaken the influence of the carrier observation noise and the pseudorange observation noise.

[0058] Among them, the Hatch filtering equation is as follows:

[0059]

[0060] In the formula, is the filtered double-difference ambiguity, is the double-difference ambiguity for the current epoch, is the filtered double-difference ambiguity for the previous epoch, and locktime is the continuous lock count of the current non-reference satellite i.

[0061] S004: Then, round the floating-point solution of the smoothed ultra-wide-lane combined ambiguity to obtain the fixed solution of the ultra-wide-lane combined ambiguity. Further, to prevent interference from large noise and ensure the correctness of rounding and fixing, satellites with ambiguity residuals exceeding 0.2 cycles can also be excluded.

[0062] The rounding formula is:

[0063]

[0064] where round is the rounding operation, is the fixed solution of the ultra-wide-lane combined ambiguity.

[0065] S005: Use the double-difference carrier observations of the fundamental frequencies B1I and B3I to construct the ionosphere-free wide-lane combination. Then, use the already fixed ultra-wide-lane combinations E1(-1,0,0,1), E2(0,-1,1,0) ambiguities and the double-difference carrier observations to combine with the wide-lane combined double-difference carrier observations, so as to obtain the floating-point solution of the wide-lane combination (1,0,-1,0) ambiguity The specific expression is as follows:

[0066]

[0067] In the formula, i and j are satellite identifiers, b is the reference station identifier, r is the monitoring station identifier, K1 and K2 are constants, is the floating-point solution of the wide-lane combination ambiguity composed of B1I and B3I, λ (1,0,-1,0) is the wide-lane combination wavelength, and are the ultra-wide-lane combined carrier observations, is the double-difference geometric station-satellite distance, is the double-difference tropospheric delay, and are both the fixed solutions of the ultra-wide-lane combined ambiguity, λ (-1,0,0,1) and λ (0,-1,1,0) are both the ultra-wide-lane combined wavelengths.

[0068] S006: Again, use the Hatch filtering equation in S003 to filter the floating-point solution of the wide-lane combination ambiguity, and use the rounding and fixing method in S004 to round and fix the filtered and smoothed floating-point solution of the wide-lane combination ambiguity to obtain the fixed solution of the wide-lane combination ambiguity. Further, satellites with residuals exceeding 0.3 cycles can also be excluded.

[0069] The rounding formula is:

[0070]

[0071] Among them, round is the rounding operation, is the fixed solution of the wide-lane combined ambiguity.

[0072] S007: Use the double-difference carrier observations and double-difference pseudorange observations of the fundamental frequencies B1I and B3I to construct an ionosphere-free combination, and obtain the ionosphere-free combination double-difference carrier observations, double-difference pseudorange observations, and double-difference ambiguity float solution.

[0073] Specifically, the double-difference carrier observations and double-difference pseudorange observations of the fundamental frequencies B1I and B3I of the BeiDou-3 satellites can be used to form an ionosphere-free combination, and the following ionosphere-free combination double-difference observation equations are constructed:

[0074]

[0075] In the above equations, i and j are satellite identifiers, b is the reference station identifier, and r is the monitoring station identifier. is the ionosphere-free combination double-difference pseudorange observation. is the ionosphere-free combination double-difference carrier observation. is the ionosphere-free combination double-difference ambiguity float solution, f1 and f3 are the frequencies of B1I and B3I respectively. and are the double-difference carrier observation and double-difference pseudorange observation of the fundamental frequency B1I. and are the double-difference carrier observation and double-difference pseudorange observation of the fundamental frequency B3I.

[0076] Using formula (14) in the above observation equations, the ionosphere-free combination double-difference ambiguity float solution can be obtained.

[0077] S008: Construct the Kalman filter equation related to the ionosphere-free combination ambiguity, and use the Kalman filter equation to estimate the zenith tropospheric wet delay, obtain the ionosphere-free combination double-difference ambiguity float solution that weakens the influence of the zenith tropospheric wet delay and the influence of observation noise, and finally improve the fixed effect of the fundamental frequency B1I ambiguity float solution of.

[0078] S009: Substitute the filtered and smoothed ionosphere-free combination ambiguity float solution and the fixed solution of the wide-lane combined ambiguity into formula (15) to obtain the fundamental frequency B1I ambiguity float solution

[0079]

[0080] S010: Construct the ambiguity matrix X and the ambiguity matrix Q related to the fundamental frequency B1I ambiguity, and then perform the LAMBDA search on the floating-point solution of the double-differenced ambiguity of the fundamental frequency B1I to obtain the fixed solution of the double-differenced ambiguity of the fundamental frequency B1I

[0081] The matrix X is composed of the floating-point solution of the fundamental frequency B1I ambiguity solved in step S009 and its expression is as follows:

[0082]

[0083] where j is the reference satellite identifier, i, k, t are non-reference satellite identifiers, r is the monitoring station identifier, and b is the reference station identifier.

[0084] Due to the transitivity of errors, and have the same covariance, so the ambiguity matrix Q is the ambiguity part of the covariance matrix in the ionosphere-free combined Kalman filter equation.

[0085] S011: Obtain the single-differenced residual sequence of the carrier observations of the fundamental frequency B1I based on the zero-mean hypothesis, and then extract the low-frequency component of the single-differenced residual (i.e., the multipath error sequence in the observations) based on wavelet analysis.

[0086] Specifically, a period of continuous 7-day GNSS observation data can be collected, and using the above-mentioned fixed ambiguity, based on the zero-mean hypothesis (i.e., the mean of the random error term is 0), obtain the single-differenced residual sequence of the carrier observations at the B1I frequency point, and then use wavelet transform to remove the high-frequency components in the single-differenced residual sequence to obtain the low-frequency component in the single-differenced residual sequence.

[0087] Since the application scenario is a sluice, the sluice is close to the water surface, and is usually completely blocked within the range of horizontal 0 - 180 degrees and elevation angle 0 - 80 degrees, with relatively serious multipath errors, which have a great impact on the ambiguity fixation rate and positioning accuracy of conventional positioning methods, and it is difficult to achieve fast and precise positioning in an environment with large multipath errors and severe satellite occlusion; and because the environment such as buildings around the sluice does not change much over time, it can be regarded as a structured environment. In a structured environment, the multipath errors suffered by each satellite at each frequency point have spatial domain repeatability, so a half-sky model can be used to weaken the multipath errors.

[0088] S012: Construct a half-sky model based on the minimum elevation angle latitude and the minimum azimuth angle longitude.

[0089] Based on the single-difference residual sequence of the carrier observations of the fundamental frequency B1I collected in the previous period for seven consecutive days, for the B1I frequency band of the BeiDou-3 satellites, a half-sky model is constructed with the elevation angle as the latitude and the azimuth angle as the longitude.

[0090] Specifically, with the monitoring station as the origin, a half-sky model is constructed with the elevation angle Ele (0 - 90°) as the latitude and the azimuth angle Azi (0 - 360°) as the longitude. The lowest elevation angle is EL min , and the highest elevation angle is EL max , and the grid points are divided with the minimum grid latitude d ele and the minimum grid longitude d azi .

[0091] Substitute the low-frequency component in the single-difference residual sequence obtained in step S011 into formula (17) to obtain the half-sky model of each B1I frequency band of the BeiDou-3 satellites (except for the geostationary orbit satellites in the BeiDou-3 satellites, as the geostationary orbit satellites do not broadcast the B1C and B2a frequency bands and cannot construct the above-mentioned ultra-wide-lane combination).

[0092] Assume that there is a BeiDou-3 satellite i in a grid point m. The multipath error parameter for the B1I frequency band of the BeiDou-3 satellite i is constructed as follows:

[0093]

[0094] In the formula: Mul m,i,B1I is the multipath error of the B1I frequency band of the BeiDou-3 satellite i in the grid point m, and sd i,B1I,k is the k-th single-difference residual among the n single-difference residuals of the B1I frequency band of the BeiDou-3 satellite i in the grid point m.

[0095] S013: When monitoring the monitoring point subsequently, first execute step S001 to construct the double-difference observation equation, then use the half-sky model to weaken the multipath error of the fundamental frequency B1I double-difference carrier observations, and then execute steps S002 - S010 to solve the fixed solution of the fundamental frequency B1I double-difference ambiguity.

[0096] After completing the half-sky model modeling, subtract the multipath error values corresponding to the current elevation angle and azimuth angle grid in the half-sky multipath error model of the reference satellite i and the non-reference satellite j to obtain the double-difference multipath error of the half-sky model of the monitoring point. Then directly subtract the double-difference multipath error of the half-sky model from the B1I frequency band double-difference carrier observations. Its expression is as follows:

[0097]

[0098] In the formula, the equation is the double-difference carrier observation of the B1I frequency band after weakening the multipath error, is the double-difference carrier observation value without weakening the multipath error, Mul m,i,B1I is the single-difference multipath error of the reference satellite i of the monitoring station within the grid m. Mul n,j,B1I is the single-difference multipath error of the non-reference satellite j within the grid n. Then, using the steps S002 to S010, the fixed solution of the ambiguity of satellite j is obtained, thereby improving the fixing rate of the ambiguity and the positioning accuracy.

[0099] S014: Using the ultra-wide-lane combination E1(-1,0,0,1), E2(0,-1,1,0) ambiguity fixed solution and the wide-lane combination (1,0,-1,0) ambiguity fixed solution and the fundamental frequency B1I double-difference ambiguity fixed solution are combined to separately obtain the B2a ambiguity fixed solution the B3I ambiguity fixed solution and the B1C ambiguity fixed solution

[0100] The specific combination method is as follows:

[0101]

[0102] S015: Substitute the fundamental frequency ambiguity back to obtain the coordinate change amount of the monitoring point, and based on this, determine whether the monitoring point is deformed.

[0103] Substitute the fundamental frequency ambiguity fixed solution back to obtain the coordinate change amount of the monitoring point. The specific steps are as follows:

[0104] Take the ambiguity-related covariance matrix Q and the ambiguity matrix X in step S010, and use the above fundamental frequency B1I double-difference ambiguity fixed solution to construct the B1I double-difference ambiguity fixed solution matrix X fix , the matrix Q ab is the covariance part of the ambiguity and the coordinate correction term of the matrix Q, and the matrix X a is the coordinate correction amount part in the matrix X. The coordinate correction amount matrix X can be solved using the following equation xyz :

[0105] X xyz = X a - Q ab · Q -1 · (X a - X fix )(21)

[0106] The plane coordinate correction amount matrix X xyz ​It is a three-row and one-column matrix, corresponding to the correction amounts in the X, Y, and Z directions respectively. It reflects the change amount of the monitoring point coordinate at the current epoch relative to the initial coordinate (the initial coordinate is calculated by using one-day continuous data through the GAMIT software after the monitoring station is established), that is, the deformation amount of the monitoring point. When the deformation amount of the monitoring point exceeds the preset threshold, it is considered that the monitoring point has a relatively serious deformation and an alarm is issued. Thus, the real-time deformation monitoring function can be realized in a semi-occluded environment with poor satellite geometric distribution, few observable satellites, reduced quality of observation data, and serious influence of multipath error.

[0107] It should be noted that during the subsequent monitoring process, whether to re-model can be considered according to whether the environment of the monitoring point has changed. The modeling process can refer to the modeling process of the S011-S012 half-sphere model, which will not be elaborated here.

[0108] Embodiment 2 discloses a sluice deformation monitoring system in a semi-occluded environment, which mainly includes Beidou-3 satellites, a reference station, and a monitoring station; among them, the reference station is used to receive GNSS observation data and navigation ephemeris data and send them to the monitoring station; the monitoring station is used to receive the GNSS observation data and navigation ephemeris data sent by the reference station, and execute the sluice deformation monitoring method in the semi-occluded environment described in Embodiment 1. The specific method will not be elaborated here.

[0109] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for monitoring the deformation of a sluice under a semi-occluded environment, characterized in that, It includes the following steps: S001: Select four frequencies, namely B1I, B2a, B3I, and B1C of the BeiDou-3 satellites as the basic frequencies from the received GNSS observation data X1 of the reference station and the GNSS observation data X2 obtained by the monitoring station itself. Use the carrier phase observations and pseudorange observations of the basic frequencies to construct basic frequency double-difference observation equations, and obtain the double-difference carrier phase observations and double-difference pseudorange observations of the basic frequencies; S002: Use the double-difference carrier phase observations and double-difference pseudorange observations of the basic frequencies, combine them according to different coefficients, construct two groups of geometry-free and ionosphere-free ultra-wide-lane combinations, and obtain the floating-point solutions of the ultra-wide-lane combination ambiguities; S003: Filter the ultra-wide-lane combination ambiguities to obtain the smoothed floating-point solutions of the ultra-wide-lane combination ambiguities; S004: Round and fix the smoothed floating-point solutions of the ultra-wide-lane combination ambiguities to obtain the fixed solutions of the ultra-wide-lane combination ambiguities; S005: Use the double-difference carrier phase observations of the basic frequencies B1I and B3I to construct an ionosphere-free wide-lane combination, and then use the fixed solutions of the ultra-wide-lane combination ambiguities and the double-difference carrier phase observations and the double-difference carrier phase observations of the wide-lane combination to perform a combination to obtain the floating-point solutions of the wide-lane combination ambiguities; S006: Filter the wide-lane combination ambiguities, and then round and fix the floating-point solutions of the wide-lane combination ambiguities after filtering and smoothing to obtain the fixed solutions of the wide-lane combination ambiguities; S007: Use the double-difference carrier phase observations and double-difference pseudorange observations of the basic frequencies B1I and B3I to construct an ionosphere-free combination, and obtain the double-difference carrier phase observations, double-difference pseudorange observations, and double-difference floating-point solutions of the ambiguities of the ionosphere-free combination; S008: Use the Kalman filter equation to filter the ambiguities of the ionosphere-free combination to obtain the double-difference floating-point solutions of the ambiguities of the ionosphere-free combination that weaken the influence of the zenith tropospheric wet delay and the influence of the observation noise; S009: Calculate the double-difference floating-point solutions of the ambiguities of the basic frequency B1I based on the filtered and smoothed double-difference floating-point solutions of the ambiguities of the ionosphere-free combination and the fixed solutions of the wide-lane combination ambiguities; S010: Construct the ambiguity matrix Q and the ambiguity matrix X related to the double-difference ambiguities of the basic frequency B1I, and search the double-difference floating-point solutions of the ambiguities of the basic frequency B1I through the LAMBDA algorithm to obtain the fixed solutions of the double-difference ambiguities of the basic frequency B1I; S011: For the GNSS observation data continuously collected for several days, obtain the single-difference residual sequence of the carrier phase observations of the basic frequency B1I based on the zero-mean hypothesis, and then extract the low-frequency components in the single-difference residual sequence based on wavelet analysis; S012: For the basic frequency B1I, construct a half-sky multi-path error model of the basic frequency B1I based on the minimum elevation angle latitude and the minimum azimuth angle longitude; S013: In subsequent monitoring, first execute step S001 to construct the double-difference observation equations, then use the half-sky multi-path error model to weaken the multi-path errors of the double-difference carrier phase observations of the basic frequency B1I, and then execute steps S002 to S0010 to solve the fixed solutions of the double-difference ambiguities of the basic frequency B1I; S014: Combine the fixed solutions of the ultra-wide-lane combination ambiguities, the fixed solutions of the wide-lane combination ambiguities, and the fixed solutions of the double-difference ambiguities of the basic frequency B1I to separately obtain the fixed solutions of the double-difference ambiguities of the basic frequencies B2a, B3I, and B1C; S015: Substitute the fixed solutions of the double-difference ambiguities of the fundamental frequencies B1I, B2a, B3I, and B1C to obtain the coordinate change amounts of the lock monitoring points. When the deformation amount of the monitoring point exceeds the preset threshold, it is determined that the monitoring point has undergone severe deformation; In the step S014, the ambiguity fixed solutions of the ultra-wide lane combinations E1(-1, 0, 0, 1) and E2(0, -1, 1, 0) are used and the ambiguity fixed solution of the wide lane combination (1, 0, -1, 0) and the ambiguity fixed solution of the dual-difference of the fundamental frequency B1I are combined to separately obtain the ambiguity fixed solution of the dual-difference of the fundamental frequency B2a the ambiguity fixed solution of the dual-difference of the fundamental frequency B3I and the ambiguity fixed solution of the dual-difference of the fundamental frequency B1C The combination method is as follows:

2. The method for monitoring the deformation of the sluice according to claim 1, characterized in that, In the step S001, the double-difference observation equations include double-difference carrier observation equations and double-difference pseudorange observation equations, which are specifically as follows: Where \(i\) and \(j\) are satellite identifiers, \(b\) is the reference station identifier, and \(r\) is the monitoring station identifier. is the double-differenced carrier observation. is the double-differenced pseudorange observation. is the double-differenced geometric station-satellite distance. is the double-differenced ionospheric delay. is the double-differenced tropospheric delay. is the double-differenced ambiguity. is the double-differenced multipath error. are the double-differenced carrier observation noise and the double-differenced pseudorange observation noise, respectively.

3. The method for monitoring the deformation of the sluice according to claim 2, wherein, In the step S002, the two ultra-wide-lane combinations are E1(-1, 0, 0, 1) and E2(0, -1, 1, 0), and the combined observation equations are as follows: Where \(i\) and \(j\) are satellite identifiers, \(b\) is the reference station identifier, and \(r\) is the monitoring station identifier. is the combined double-difference carrier observation value, and \(\eta\) (m,n,p,q) and \(\eta\) (a',b',c',d') are the combined ionospheric amplification factors, \(\lambda\) (m,n,p,q) is the combined carrier wavelength. and are the combined carrier observation noise and the combined pseudorange observation noise respectively. is the combined double-difference pseudorange observation value. \(f1\), \(f2\), \(f3\), and \(f4\) correspond to the frequencies of carriers B1I, B2a, B3I, and B1C respectively. The double-difference carrier observations corresponding to carrier waves B1I, B2a, B3I, and B1C respectively, The double-difference pseudorange observations corresponding to carrier waves B1I, B2a, B3I, and B1C respectively; Among them, the combination coefficients in the combination E1 are: m = -1, n = 0, p = 0, q = 1; the combination coefficients in the combination E2 are: m = 0, n = -1, p = 1, q = 0; a', b', c', d' are the combination coefficients of the double-difference pseudorange observation equations to be determined related to m, n, p, q; By means of the combined observation equation, make a'+b'+c'+d' = 1, η (m,n,p,q) +η (a',b',c',d') = 0 to eliminate the tropospheric delay, orbit error and ionospheric delay error; Meet simultaneously Even if the observation noise of the combined observations is minimized, the values of a', b', c', and d' can be obtained by the minimum norm method, and then the floating-point solution of the ultra-wide-lane ambiguity can be obtained through formula (7): In the step S005, the floating-point solution expression of the wide-lane combination ambiguity is as follows: where \(i\) and \(j\) are satellite identifiers, \(b\) is the reference station identifier, \(r\) is the monitoring station identifier, and \(K1\), \(K2\) are constants. is the fixed solution of the wide-lane combination ambiguity composed of B1I and B3I, \(\lambda\) (1,0,-1,0) is the wide-lane combination wavelength, is the wide-lane combination carrier observation, and are the ultra-wide-lane combination carrier observations, is the double-differenced geometric station-satellite distance, is the double-differenced tropospheric delay, and are both the fixed solutions of the ultra-wide-lane combination ambiguity, \(\lambda\) (-1,0,0,1) and \(\lambda\) (0,-1,1,0) are both the ultra-wide-lane combination wavelengths; In the step S007, an ionosphere-free combination is constructed using the double-difference carrier observations and double-difference pseudorange observations of the fundamental frequencies B1I and B3I, and the ionosphere-free combination double-difference observation equation is obtained as follows: where \(i\) and \(j\) are satellite identifiers, \(b\) is the reference station identifier, and \(r\) is the monitoring station identifier. is the ionosphere-free combined double-difference pseudorange observation value. is the ionosphere-free combined double-difference carrier observation value. is the ionosphere-free combined double-difference ambiguity float solution, \(f_1\) and \(f_3\) are the frequencies of B1I and B3I respectively. and are the double-difference carrier observation value and double-difference pseudorange observation value of the fundamental frequency B1I. and are the double-difference carrier observation value and double-difference pseudorange observation value of the fundamental frequency B3I. In the step S009, the floating-point solution of the B1I double-difference ambiguity of the fundamental frequency is calculated as follows: In the step S010, the ambiguity matrix X is composed of the floating-point solutions of the double-difference ambiguities of the fundamental frequency B1I solved in the step S009, and the ambiguity matrix Q is the ionosphere-free combination ambiguity part of the covariance matrix in the ionosphere-free combination Kalman filter equation.

4. The method for monitoring the deformation of a sluice according to claim 1, characterized in that In the steps S003 and S006, Hatch is used for filtering; the filtering equation of Hatch is as follows: In the formula, is the filtered double-difference ambiguity, is the double-difference ambiguity at the current epoch, is the filtered double-difference ambiguity at the previous epoch, and locktime is the continuous lock count of the current non-reference satellite i.

5. The method for monitoring the deformation of a sluice according to claim 1, characterized in that, In the step S004, the rounding formula is: where round is the rounding operation, is the fixed solution of the ultra-wide lane combined ambiguity; In the step S006, the rounding formula is: where round is the rounding operation, is the fixed solution of the wide-lane combined ambiguity.

6. The deformation monitoring method of the sluice according to claim 1, characterized in that, The step S004 further includes: excluding the satellites with ambiguity residuals exceeding the first preset value; the step S006 further includes: excluding the satellites with ambiguity residuals exceeding the second preset value.

7. The method for monitoring the deformation of a sluice according to claim 1, characterized in that, In the step S012, the method for constructing the half-sky multipath error model is as follows: Taking the monitoring station as the origin, using the elevation angle Ele as the latitude, where Ele ranges from 0 to 90°, and the azimuth angle Azi as the longitude, where Azi ranges from 0 to 360°, a half - sphere multipath error model is constructed, with the lowest elevation angle being EL min and the highest elevation angle being EL max , and dividing the grid points with the minimum grid latitude d ele and the minimum grid longitude d azi ; Substitute the low-frequency components in the single-difference residual sequence obtained in the step S011 into the formula (17) to obtain the half-sky multipath error model of the fundamental frequency B1I. Among them, the multipath error parameters for the fundamental frequency B1I of the BDS-3 satellite i within the network point m are: Where: Mul m,i,B1I is the B1I multipath error of the BeiDou-3 satellite i within the grid point m, and sd i,B1I,k is the k-th single-difference residual among the n single-difference residuals of the B1I baseband observations.

8. The method for monitoring the deformation of a sluice according to claim 1, wherein, The step S015 specifically includes: Take the ambiguity matrix Q and the ambiguity matrix X related to the fundamental frequency B1I ambiguity in step S010, and use the fixed solution of the B1I double-difference ambiguity Construct the B1I double-difference ambiguity fixed solution matrix X fix , matrix Q ab is the covariance part of the ambiguity and the coordinate correction term of the ambiguity matrix Q, and matrix X a is the coordinate correction amount part in the ambiguity matrix X. Use formula (21) to solve the monitoring point coordinate correction amount matrix X xyz : X xyz = X a - Q ab · Q -1 · (X a - X fix )(21); In the formula, the coordinate correction matrix X xyz is a matrix with three rows and one column, corresponding to the corrections in the X, Y, and Z directions respectively. It reflects the change in the coordinates of the monitoring point at the current epoch relative to the initial coordinates, that is, the deformation amount of the monitoring point.

9. A water gate deformation monitoring system in a semi-occluded environment, characterized in that, It includes BDS-3 satellites, a reference station, and a monitoring station; the reference station is used to receive GNSS observation data and navigation ephemeris data and send them to the monitoring station; the monitoring station is used to receive the GNSS observation data and navigation ephemeris data sent by the reference station, and execute the lock deformation monitoring method under the semi-occluded environment according to any one of claims 1 to 8.

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