A method and system for river-crossing leveling

Abstract

The present application belongs to the field of engineering surveying technology, and specifically discloses a river-crossing leveling method and system, which comprises the following steps: setting four control points on the two banks of the water area to be measured, installing a centering rod tool on each control point, and integrating an upper prism and a lower prism with a preset fixed vertical interval on each centering rod tool; erecting a first total station and a second total station on the two banks of the water area, synchronously and oppositely observing the upper prism and the lower prism on the centering rod tool arranged on the opposite bank, and obtaining the vertical angle and the slant distance data of each observation target; based on the vertical angle and the slant distance data, and using the preset fixed vertical interval as a checking condition, the height difference between the target positions on the two banks is calculated. The present application introduces a double-layer prism tool into a physically forced closed checking condition, combines with the traditional quadrilateral geometric closed checking, greatly enhances the data redundancy and the reliability of the results, and can effectively identify and separate systematic errors.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engineering surveying, and particularly relates to a river-crossing leveling method and system. BACKGROUND

[0002] In the construction and operation monitoring of large linear projects across a river, accurately transferring the height datum from one bank to the opposite bank, i.e. river-crossing leveling, is a crucial fundamental work. Its measurement accuracy directly affects the construction docking and structural safety of key structures such as bridges and tunnels.

[0003] Traditional river-crossing leveling methods, such as direct leveling, are limited by the instrument line of sight length and cannot be used in wide water areas. Therefore, the trigonometric leveling method has become the mainstream technology, which usually uses total stations to observe from both banks, and calculates the height difference by measuring the vertical angle and slant distance. However, the existing technology has the following significant problems in practical application:

[0004] Non-synchronous observation error: The traditional trigonometric leveling method usually adopts a time-sharing and grouping mode for observation, i.e. one instrument observes all target points on the opposite bank first, and then the other instrument observes. Since the atmospheric environment (such as temperature, air pressure, humidity) is dynamically changing during observation, this non-synchronous observation mode causes the instruments on both banks to collect data at different times, which cannot effectively eliminate the influence of dynamic environmental errors such as atmospheric refraction and temperature gradient on height measurement, resulting in unstable measurement results and difficulty in ensuring accuracy.

[0005] Insufficient closure checking conditions: The traditional method mostly uses single-layer prisms as observation targets. Although geometric checking can be performed by constructing a quadrilateral loop, the checking dimension is single. When there are systematic errors in the observation data, it is often difficult to find and separate the problems relying only on geometric closure difference, and the data redundancy is low and the reliability is insufficient.

[0006] Low work efficiency and automation level: The traditional work process relies on manual recording, and in order to meet the accuracy requirements, multiple round-trip observations are needed, the process is cumbersome, the field work is heavy, and the time cost is high. Especially in the "double-line crossing river" (i.e. laying two parallel observation lines) scheme, the number of measurement points and the workload are doubled.

[0007] Therefore, there is an urgent need for a new river-crossing leveling method and system that can overcome the above-mentioned defects and achieve high accuracy, high efficiency and high reliability. SUMMARY

[0008] The present application aims to overcome the deficiencies of the prior art and provide a river-crossing leveling method and system to solve the problems of large non-synchronous observation error, insufficient closure checking conditions, and low work efficiency in the background art.

[0009] Technical solution: The cross-river leveling method provided by the application comprises the following steps.

[0010] S1: Four control points are arranged on both banks of the water area to be measured to form a cross-river quadrilateral control network, each control point is provided with a centering rod tool having upper and lower prisms, and each centering rod tool is integrated with the upper and lower prisms having a preset fixed vertical interval;

[0011] S2: A first total station and a second total station are respectively erected on both banks of the water area.

[0012] S3: The first total station and the second total station are used to synchronously and oppositely observe the upper and lower prisms on the centering rod tools arranged on the opposite bank within a preset time synchronization error range, and vertical angle and slant distance data of each observation target are obtained.

[0013] S4: Based on the vertical angle and slant distance data, and using the preset fixed vertical interval as a checking condition, the height difference between the target positions on both banks is calculated.

[0014] Further improve the above technical solution, the length of the two short sides of the cross-river quadrilateral control network is approximately equal, the length difference is not greater than 5%, and the first total station and the second total station are respectively erected near the midpoint of the short side.

[0015] Further, before starting the measurement, the following preparation steps are further included: correcting the compensator, the shaft system error of the horizontal shaft and the vertical shaft, and the automatic aiming error of the first total station and the second total station; and calibrating the preset fixed vertical interval of the upper and lower prisms of each set of centering rod tools, so that the calibration error is not greater than 0.5mm.

[0016] Further, the synchronous and opposite observation includes: a first observation period: the first total station and the second total station synchronously and oppositely observe all the upper prisms of the centering rod tools on the opposite bank; a second observation period: the first total station and the second total station synchronously and oppositely observe all the lower prisms of the centering rod tools on the opposite bank; the first observation period and the second observation period constitute a single measurement return observation.

[0017] Further, it further includes exchanging the positions of the first total station, the second total station and the centering rod tools on both banks, and repeating the synchronous and opposite observation step to form a double measurement return observation.

[0018] Further, based on the synchronous and opposite observation of the first total station and the second total station on the upper prisms and the lower prisms of the four control points A, B, C and D, the vertical angle and the slant distance S of each prism are obtained; the height difference initial value of each segment of the cross-river quadrilateral control network is calculated using the formula, including the height difference from the point A to the point B The elevation difference between point B and point C is The elevation difference between point C and point D is And the elevation difference between point D and point A is ;

[0019] The formula is: Where D is the horizontal distance. vertical angle , For the instrument to be high, R is the height of the prism, R is the Earth's radius, and k is the atmospheric refractive index.

[0020] The elevation differences of each segment are algebraically summed along the closed loop to obtain the elevation closure difference. :

[0021] ;

[0022] Obtain the total length L of the closed loop, and calculate the allowable limit of the elevation closure error using the following formula. :

[0023] ;

[0024] The accuracy is checked using the loop closure error formed by the initial values ​​of the elevation differences in each segment. The absolute value of the calculated elevation closure error is then used. With the aforementioned allowable limit If a comparison is made, If the accuracy of the observed data is satisfactory, then the data accuracy of this observation is deemed acceptable.

[0025] The positions of the first total station, the second total station, and the centering rods on both banks are swapped, and the synchronous and opposing observation steps are repeated to form a double-round observation. The leveling network is adjusted using adjustment software, and the most probable elevation values ​​of the four control points A, B, C, and D are output.

[0026] Furthermore, for each synchronous, opposing observation of the same pair of central rod fixtures' upper and lower prism data, the height difference observation value is calculated in real time and compared with the preset fixed vertical spacing. If the difference exceeds the preset limit, the observation data is marked as invalid or a retest is triggered.

[0027] Furthermore, the first total station and the second total station are measuring robots with automatic target recognition capabilities, and the synchronous and opposing observation steps are achieved by the measuring robots automatically searching, aiming, and recording data.

[0028] The cross-river leveling monitoring system used to implement the above method includes:

[0029] At least four centering rod fixtures are deployed on both banks of the water area to be measured to form a quadrilateral control network across the river. Each centering rod fixture integrates a pair of upper prisms and a lower prism, and there is a fixed vertical distance between the upper prisms and the lower prisms that has been pre-calibrated.

[0030] The first total station and the second total station were respectively deployed at the midpoint of the control points on both sides of the water area to be measured;

[0031] The data processing unit is configured to perform the following operations: control the first total station and the second total station to synchronously and oppositely observe the upper and lower prisms of the centering rod fixture set up on the opposite bank, and receive the observation data; use the fixed vertical spacing as a mandatory physical constraint to perform real-time verification of the received observation data, and calculate the elevation transfer result between the two banks through leveling network adjustment based on the data that has passed the verification.

[0032] Furthermore, the data processing unit is further configured to: before calculating the elevation difference, use synchronously collected meteorological data to perform real-time meteorological correction on the observation data in order to eliminate the influence of atmospheric refraction on the distance measurement.

[0033] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0034] This invention eliminates asynchronous errors caused by dynamic changes in the atmospheric environment in real time through synchronous, opposite observations using total stations on both sides of the river. Simultaneously, the innovative double-layer prism fixture introduces a physically forced closure check condition (fixed elevation difference). This, combined with the traditional quadrilateral geometric closure check, constitutes a "double closure" verification system, which greatly enhances data redundancy and the reliability of results, and can effectively identify and separate systematic errors.

[0035] This invention employs a surveying robot equipped with Automatic Target Recognition (ATR) functionality, automating the entire observation process and reducing manual intervention. The dual-closed-loop check system enables "single-line river crossing" to achieve or even surpass the accuracy of traditional "double-line river crossing," reducing fieldwork workload by approximately 50% and significantly shortening single observation time. This increased efficiency directly reduces labor and time costs; simultaneously, by optimizing the observation network and process, unnecessary repetitive observations are reduced, further lowering the overall cost of the surveying project. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the layout of the cross-river quadrilateral control network in an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the double-layer prism centering rod tooling used in an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the detachable prism connector in an embodiment of the present invention.

[0039] Figure 4 This is a schematic diagram of the prism structure in an embodiment of the present invention. Figure 4 Image (a) is the front view of the prism. Figure 4 (b) is a side view of the prism.

[0040] Figure 5 This is a schematic diagram of the prism rod in this invention. Figure 5 (a) is the front view of the prism rod. Figure 5 (b) is a side view of the prism rod.

[0041] The attached figures are labeled as follows: 1. First total station; 2. Second total station; 101. Upper prism; 102. Lower prism; 103. Level bubble; 104. Prism rod support frame; 105. Lower prism centering rod; 1061. Upper detachable connector; 1062. Lower detachable connector. Detailed Implementation

[0042] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments described.

[0043] Example 1: The cross-river leveling system provided by this invention has the following hardware architecture:

[0044] Measurement equipment: Two Leica TM60 total stations (measuring robots), with nominal angle measurement accuracy ≤0.5″, distance measurement accuracy 1mm+1×10-6D, equipped with an automatic target recognition (ATR) module;

[0045] Centering rod fixture: adopts a double-layer prism structure, with a fixed spacing between the upper and lower prisms and a height difference ≤0.5mm, forming closed observation conditions;

[0046] Quadrilateral control network setup: Four fixed stakes are set up on both banks to form four control points A, B, C, and D. The difference in the length of the short side is ≤5%, which constitutes a forced closed observation condition.

[0047] 1. Preparations and System Calibration Before Observation

[0048] Before conducting field observations, the following preparations and calibrations must be completed to ensure the accuracy and reliability of the measurement system:

[0049] 1.1 Total Station Calibration

[0050] A comprehensive five-axis error correction was performed on the two Leica TM60 total stations (surveying robots) used in this invention, including: compensator zero point correction; horizontal axis tilt error compensation; vertical axis tilt error compensation; and automatic aiming error (ATR) calibration.

[0051] 1.2 Calibration of the center rod tooling

[0052] Precisely measure the fixed vertical distance between the upper and lower prisms of each double-layer prism centering rod fixture. A two-dimensional linear measuring tape is used for precision calibration to ensure that the calibration accuracy of the height difference is better than or equal to 0.5 mm.

[0053] 1.3 Environmental Parameters and Equipment Preparation

[0054] Prepare high-precision environmental parameter acquisition equipment, including:

[0055] Temperature sensor: Employs a PT100 platinum resistance sensor to ensure temperature measurement accuracy of ±0.5℃;

[0056] Barometer: A digital barometer is used to ensure that the barometer measurement accuracy reaches ±1.0 hPa.

[0057] 1.4 Determination of the three correction parameters for slope distance

[0058] To ensure accurate correction of subsequent slant range observations, three correction parameters need to be determined in advance: meteorological correction model: meteorological correction is performed using the Ciddor equation; instrument additive constant: the instrument's factory calibration value is used; instrument multiplication constant: the actual multiplication constant correction value is obtained through calibration using a standard baseline field.

[0059] 2. Construction of the cross-river control network

[0060] In stable areas along both banks of the river, a closed quadrilateral control network consisting of four control points A, B, C, and D is established, such as... Figure 1 As shown. Control points are set up using stainless steel marker posts. To ensure the strength of the observation pattern, the control network must meet the condition that the short sides are approximately equal in length.

[0061] 3. Synchronous observation and data acquisition using total station

[0062] This embodiment uses two total stations (total station 1 and total station 2) for synchronous counter-observation. A complete single-round observation process is as follows:

[0063] 3.1 Observations at the first station (total station 1):

[0064] Set up the first total station 1 on the opposite bank (such as the side of points C and D), which is located near the geometric midpoint of the line connecting CD.

[0065] The first total station 1 first learns in sequence the upper prisms of the centering rod fixtures at the four control points A, B, C, and D on the opposite bank to establish an automatic aiming database.

[0066] Using the full-circle observation method, the first total station 1 automatically, sequentially, and repeatedly (multiple measurements) observed the four upper prisms A, B, C, and D, automatically recording and storing the vertical angle in each direction. And the slant distance S to the memory card.

[0067] After completing the observation of the upper prism, the first total station 1 relearned and measured all the lower prisms, completing the acquisition of two-level data.

[0068] 3.2 Observations at the second station (second total station 2):

[0069] Simultaneously, the second total station 2 is set up on the station on this bank (such as the side of points A and B), which is located near the geometric midpoint of the line connecting AB.

[0070] The second total station 2 first synchronously learns and measures the lower prism of the centering rod fixture at the four control points A, B, C, and D.

[0071] Perform the full-circle direction observation method equivalent to that of the first total station 1, and record the observation data synchronously.

[0072] After completing the observation of the lower prism, the second total station 2 repeats the learning and measurement of all the upper prisms.

[0073] Through the above operations, the two total stations conducted complete observations of the upper and lower layers of prisms at all measuring points within the same time period, theoretically obtaining the height difference between the upper and lower layers of the four centering rod prisms, forming redundant data that can be used for closure verification.

[0074] 4. Dual-repetition observation scheme

[0075] To meet the requirements of GB / T 12897-2006 "National First and Second Order Leveling Measurement Specifications" and eliminate instrument system errors, a double-repetition observation scheme is adopted:

[0076] Determine the number of observations N: Determine the total number of observations N based on the grade requirements of cross-river leveling surveys.

[0077] First single-round measurement: Complete the aforementioned full observation process.

[0078] Instrument and prism swapping: After completing the first single measurement cycle, the first total station 1 and the second total station 2 on both banks are swapped, and the centering rod prism groups on both banks are also swapped.

[0079] Second single-round observation: Within the same time period, repeat the observation process to complete the second single-round observation.

[0080] These two single-round observations together constitute a complete double-round observation.

[0081] In single-round observations, the differences between observations in each direction must meet the tolerance requirements. For example, the difference between four aiming readings of the same marker line should be ≤3″; the difference between index differences should be ≤8″; and the difference between vertical angles of the same marker should be ≤4″.

[0082] 5. Data Adjustment and Accuracy Verification

[0083] Software Adjustment: Data processing was performed using the elevation adjustment software included with the Leica TM60. This software incorporates a correction model that considers the effects of external factors such as Earth's curvature, temperature, and atmospheric refraction during the adjustment calculations. The software solves the problem to obtain the relative elevation differences between each measuring point.

[0084] Network adjustment solution: The entire leveling network is rigorously adjusted using the indirect adjustment method. The weight matrix is ​​dynamically allocated based on the number of observations and the dynamic changes in on-site meteorological conditions.

[0085] Accuracy assessment: Calculate the closed loop error of quadrilateral ABCD and the difference between each measurement cycle to conduct the final accuracy assessment.

[0086] Example 2: This example uses a high-precision elevation transfer of a road-rail dual-purpose Yangtze River bridge with a cross-river distance of L=2.5km as an example.

[0087] To improve the accuracy and efficiency of cross-river leveling measurements, this invention presents a cross-river leveling point system measurement method. Two Leica TM60 measuring robots synchronously and in opposite directions observe the upper and lower layers of prisms on both banks, automatically recording distances and vertical angles, and calculating the elevation difference. During measurement, when the cross-river leveling distance is no greater than 300m, the instrument's line of sight should be 2m above the water surface; when the distance is greater than 500m, the calculated line of sight should be used. The vertical angle of the line of sight should not exceed 3°, and the weather conditions should be cloudy, without rain, fog, or wind. This method can simultaneously determine the elevation difference between the upper and lower layers of a single prism, and is equivalent to using a full-circle observation method for prism observation. Increasing the closure condition improves measurement accuracy, and synchronous observation according to specifications eliminates the influence of atmospheric refraction and Earth's curvature, further improving observation accuracy. The instrument simultaneously observes all centering rod prisms, improving measurement efficiency and offering significant advantages over previous methods of observing a single centering rod prism. Previous regulations for crossing rivers often required a double-track crossing. This method employs a double-prism measurement, increasing the closure condition and changing the double-track crossing to a single-track crossing, thus improving both accuracy and measurement efficiency. This method utilizes the finite difference method to effectively eliminate the effects of Earth's curvature and atmospheric refraction. Multiple measurements of the elevation difference taken by two instruments are averaged to obtain the elevation difference between the two banks. The measurement results form a closed loop, which is then used for leveling network adjustment calculations. This observation method is simple, efficient, highly accurate, allows for multiple verification submissions, and has a high degree of automation; data acquisition is automatically completed by the instrument.

[0088] 1. System preparation and innovative tooling calibration

[0089] Before observation, in addition to performing comprehensive five-axis error correction on two Leica TM60 total stations, preparing high-precision thermo-pressure equipment, and determining the slope distance correction parameters, the core preparatory work of this method lies in the precise calibration of the innovatively designed centering rod fixture.

[0090] Double-layer prism centering rod fixture: This method uses a specially designed double-layer prism fixture. (Refer to...) Figure 2 to Figure 5 The fixture has an upper prism 101 and a lower prism 102 fixed on the same vertical prism rod. The bottom of the upper prism 101 is fixed above the lower prism centering rod 105 by an upper detachable connector 1061. The bottom of the lower prism 102 is fixed above the vertical rod by a lower detachable connector 1062. The vertical rod is supported by a prism rod support frame 104. A level bubble 103 is provided at the top of the vertical rod.

[0091] The vertical distance between the centers of the upper prism 101 and the lower prism 102 It is a fixed value that has been precisely calibrated beforehand. In this embodiment, calibration is performed using a two-dimensional linear measuring tape, ensuring... The calibration error is no greater than 0.5mm. This is a known, high-precision... The value is the cornerstone of the physical closure constraint for achieving "hierarchical mutual inspection" in this method, and is one of the key innovations that distinguishes it from the traditional single-layer prism method.

[0092] 2. Innovate observation network type and synchronous observation mechanism

[0093] Network Innovation – “Single-Line River Crossing” Replaces “Double-Line River Crossing”: This method adopts an optimized “single-line river crossing” quadrilateral control network (such as…). Figure 1 The points A, B, C, and D shown replace the traditional redundant "double-line river-crossing" network designed to ensure accuracy. This structural simplification directly reduces the fieldwork workload by 50%, while its accuracy is guaranteed by the following synchronous observation mechanism and dual closed-loop verification system.

[0094] Synchronous counter-observation mechanism: To address the atmospheric time-varying errors introduced by traditional asynchronous observations, this method establishes a rigorous synchronous observation mechanism. The first total station 1 (set up near the midpoint of CD) and the second total station 2 (set up near the midpoint of AB) are synchronized in time (synchronization error ≤ 1ms) to collect data from opposite directions at the same time (1Hz sampling rate).

[0095] Parallel control and data acquisition: Two instruments (0.5" angular measurement accuracy) synchronously perform target search (ATR accuracy ±0.3mm) and data acquisition. For example, when the first total station 1 observes the upper prism at point C, the second total station 2 simultaneously observes the upper prism at point A. This high degree of synchronization in the time domain ensures the consistency of atmospheric conditions (especially the atmospheric refractive index k) along the observation paths of the instruments on both sides, laying the foundation for subsequent elimination of atmospheric influences and Earth curvature errors through differential techniques.

[0096] 3. Data Processing: A dual closed-loop system integrating physical constraints and geometric checks.

[0097] Data processing is the core element that demonstrates the innovation of this method, integrating technologies based on... Physical closure check and geometric closure check based on quadrilateral ring.

[0098] Let the slant distance between the two points be S, and the vertical angle be θ. If the height of the instrument is i and the height of the prism is v, then the formula for the height difference between the two points is:

[0099] Horizontal distance The calculation formula is: ,but:

[0100] (1)

[0101] Since the Earth's surface is curved, the elevation transfer between two points requires correction for the Earth's curvature. Let the Earth's radius be R and the horizontal distance be D, then the Earth curvature correction term C is:

[0102] (2)

[0103] When light travels through the air, it is affected by refraction. The atmospheric refraction correction term r is approximately k times the curvature effect (k is the atmospheric refraction coefficient, typically taken as 0.08-0.15), and the calculation formula is as follows:

[0104] (3)

[0105] Including curvature and refraction corrections, the corrected elevation difference formula is updated as follows:

[0106] (4)

[0107] The principle of opposing observations, in which, in forward observation (A→B): the instrument is at point A, the prism is at point B, and the vertical angle is... slant distance The horizontal distance is: Reverse observation (B→A): The instrument is at point B, the prism is at point A, and the vertical angle is... slant distance The horizontal distance is: .

[0108] Positive elevation difference:

[0109] Reverse elevation difference:

[0110] Ideally, ,Right now;

[0111]

[0112] (5)

[0113] Earth's curvature and refractive correction term: If ,but The curvature and refractive errors are canceled out. Instrument height and prism height error: if accurately measured... , , , If the remaining error is negligible, then the error can be ignored.

[0114] Four points are set up on both sides of the river to form a quadrilateral with approximately equal short sides. The instrument is set up at the midpoint of the short side to simultaneously observe the upper and lower layers of prisms on the opposite bank.

[0115] Let the observed elevation difference of each side of the quadrilateral be . The closure error is:

[0116]

[0117] Closure Limit for: (6)

[0118] For any total station (e.g., total station 1) observing any control point (e.g., point A), the elevation difference formula is updated by combining curvature and refraction corrections:

[0119]

[0120] Where D is the horizontal distance. The vertical angle is R, the Earth's radius is k, the atmospheric refraction coefficient is i, the instrument height is v, and the prism height is v.

[0121] Height difference of the upper prism: ;

[0122] Height difference of lower prism: ;

[0123] The height difference between the two should satisfy:

[0124]

[0125] If the prism layer spacing is fixed ,but: , This represents the observation error term.

[0126] By forcibly closing the condition ( (As is known), the effects of atmospheric refraction and Earth's curvature can be separated.

[0127] This method performs real-time calculations of observations during data processing and combines them with high-precision... The difference, when compared, directly reflects the combined effects of atmospheric refraction and Earth's curvature, as well as random observation errors. By setting a dynamic limit, for example... (S is the slope distance), if If the test is automatically retried, the data quality can be monitored in real time and dynamically based on the forced closure condition of known physical quantities, and the possibility of separating systematic errors can be provided.

[0128] 3.2 Quadrilateral Loop Closure Error

[0129] After passing the hierarchical mutual inspection, a geometric check is performed.

[0130] Elevation difference calculation: The elevation difference between each side of the river crossing is calculated using the two-way observation difference method, as shown in equation (5). This method can effectively eliminate most of the systematic errors. Finally, a simplified formula for calculating the elevation difference across the river, which eliminates most of the error terms, is obtained:

[0131] (7)

[0132] The shorter sides of the quadrilaterals are approximately equal. The curvature refractive terms cancel each other out; the instrument height and prism height are accurately measured, and the error terms are eliminated.

[0133] Closure error calculation: Calculate the elevation closure error of the quadrilateral loop A→B→C→D→A:

[0134]

[0135] closure error The absolute value is compared with the standard tolerance of second-order leveling. For this embodiment, the total length L of the closed loop is: ,but Only when Only when the network accuracy is considered acceptable is the network accuracy deemed to be satisfactory.

[0136] 3.3 Rigorous Adjustment

[0137] Finally, all valid observation data (including double-review observation data) that passed the above double verification were input into the weighted least squares adjustment model to calculate the most probable elevation values ​​of the four control points A, B, C, and D. In multiple applications of this embodiment, the mean square error of the 2.5km elevation difference across the river could be controlled within ≤±1mm, fully meeting the requirements of second-order leveling.

[0138] Table 1 Comparison of the present invention with previous technologies

[0139] Contrast dimension Prior art The present application Prism structure Single-layer prism (4 independent prisms) Double-layer prism tool (fixed distance between upper and lower layers ≤0.5mm, double prisms at the same measuring point form a forced closed condition) Observation mechanism Synchronous observation of the single-layer prisms on the opposite shore by the instruments on both sides Four target points x double-layer level synchronous observation: synchronous collection of upper and lower prism data of four measuring points on both sides by the instruments on both sides Error elimination logic Eliminate the spherical and atmospheric errors by relying on quadrilateral geometry difference (formula 5) New level mutual inspection: dynamic verification of data of mutual difference of height difference between upper and lower layers, automatic re-measurement if the limit is exceeded Closed condition Single quadrilateral closed loop Double closed system: quadrilateral loop closed difference; height difference closed difference between upper and lower layers Net type design Double-line crossing river (8 measuring points are required) Single-line crossing river: only 4 measuring points + double-layer prisms, reducing the field work by 50%

[0140] This invention provides a complete, efficient, and high-precision solution for cross-river leveling measurements through innovative double-layer prism fixtures, optimized single-line grid patterns, a rigorous synchronous observation mechanism, and a dual closed-loop verification system that integrates physical and geometric constraints.

[0141] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method of river-crossing leveling, characterized by, The method comprises the following steps: S1: four control points are arranged on both banks of the water area to be measured to form a trans-river quadrilateral control network, each control point is provided with a centering rod tool with upper and lower prisms, and each centering rod tool is integrated with upper and lower prisms with a preset fixed vertical interval; S2: a first total station and a second total station are respectively erected on both banks of the water area; S3: the first total station and the second total station are used to synchronously and oppositely observe the upper and lower prisms on the centering rod tools arranged on the opposite bank within a preset time synchronization error range, to obtain vertical angle and slant distance data of each observation target; The synchronous and opposite observation comprises: A first observation period: the first total station and the second total station synchronously and oppositely observe the upper prisms of all centering rod tools on the opposite bank; A second observation period: the first total station and the second total station synchronously and oppositely observe the lower prisms of all centering rod tools on the opposite bank; The first observation period and the second observation period form a single measurement return observation; The positions of the first total station, the second total station and the centering rod tools on both banks are exchanged, and the synchronous and opposite observation step is repeated to form a double measurement return observation; S4: based on the vertical angle and slant distance data, and using the preset fixed vertical interval as a checking condition, the height difference between the target positions on both banks is calculated, comprising: The vertical angles of the upper and lower prisms of the four control points A, B, C and D are obtained by the first and second total stations observing the prisms synchronously and oppositely and the slant distance S; the initial values of the height differences of the sections of the cross-river quadrilateral control network are calculated by using a formula, including the height difference from A to B , the height difference from B to C , the height difference from C to D , and the height difference from D to A ; The formula is: ; wherein, , is the slant range, is the vertical angle, is the instrument height, is the prism height, R is the earth radius, and k is the atmospheric refraction coefficient. The high difference values of each section are algebraically summed along the closed loop to obtain the height closure error : ； The total length L of the closed loop is obtained, and the allowable limit of the elevation closure is calculated by using the following formula : ； The accuracy is checked using the loop closure error formed by the initial values ​​of the elevation differences in each segment. The absolute value of the calculated elevation closure error is then used. With the aforementioned allowable limit If a comparison is made, If the accuracy of the observed data is satisfactory, then the data accuracy of this observation is deemed acceptable. The positions of the first total station, the second total station and the centering rod tools on both banks are exchanged, and the synchronous and opposite observation step is repeated to form a double measurement return observation, the leveling network is adjusted by adjustment software, and the most probable elevation values of the four control points A, B, C and D are output.

2. The cross-river leveling method according to claim 1, wherein, The lengths of the two short sides of the trans-river quadrilateral control network are approximately equal, the length difference is not greater than 5%, and the first total station and the second total station are respectively erected near the midpoints of the short sides.

3. The cross-river leveling method according to claim 1, wherein, Before starting the measurement, the following preparation steps are further included: the first total station and the second total station are corrected for compensator, horizontal shaft and vertical shaft system error and automatic aiming error; and the preset fixed vertical interval of the upper and lower prisms of each set of centering rod tools is calibrated to ensure that the calibration error is not greater than 0.5mm.

4. The cross-river leveling method according to claim 1, wherein, For the data of the upper and lower prisms of each centering rod tool obtained by each synchronous and opposite observation, the height difference observation value is calculated in real time, and compared with the preset fixed vertical interval, if the difference exceeds the preset limit value, the observation data is marked as invalid or triggers a re-measurement.

5. The cross-river leveling method according to claim 1, wherein, The first total station and the second total station are measurement robots with automatic target recognition function, and the synchronous and opposite observation step is realized by the measurement robots automatically searching, aiming and recording data.

6. System for implementing the method for crossing a river level measurement according to claim 1, characterized in that, Comprise: At least four centering rod tools are respectively arranged on both banks of the water area to be measured to form a trans-river quadrilateral control network, the centering rod tool is integrated with a pair of upper and lower prisms, and the upper and lower prisms have a pre-calibrated fixed vertical interval; A first total station and a second total station are respectively arranged at the midpoint positions of the control points on both banks of the water area to be measured; A data processing unit is configured to perform the following operations: controlling the first and second total stations to synchronously and oppositely observe upper and lower layer prisms of the centering rod tool arranged on the opposite bank, and receiving observation data; taking the fixed vertical interval as a mandatory physical constraint condition, performing real-time checking on the received observation data, and based on the data passing the checking, solving the height transfer result between the two banks by leveling network adjustment.

7. The system of claim 6, wherein, The data processing unit is further configured to perform real-time meteorological correction on the observation data by using synchronously collected meteorological data before solving the height difference, so as to eliminate the influence of atmospheric refraction on distance measurement.

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