A height precision measurement method based on wMPS and RTK

Abstract

This invention discloses a method for precise elevation measurement based on the fusion of wMPS and RTK real-time dynamic positioning systems, comprising: acquiring the two-dimensional planar coordinates of the point to be measured in an external coordinate system, and transforming them to the wMPS transmitter station coordinate system using a pre-calibrated coordinate transformation relationship; receiving the scanning light plane signal using a photoelectric receiver and calculating the relative phase difference when the scanning light plane sweeps across the point to be measured; establishing an instantaneous light plane constraint equation between the spatial coordinates of the point to be measured and the rotating scanning phase; substituting the coordinates of the point to be measured into the instantaneous light plane constraint equation to obtain a system of linear equations with elevation variables and the absolute phase of the rotating scan as variables, and then obtaining a linear expression for the intermediate variable of the rotating scan phase; substituting the obtained intermediate variable of the rotating scan phase into the trigonometric identity constraint to obtain the elevation variable of the point to be measured in the wMPS transmitter station coordinate system, and then outputting the three-dimensional coordinates in the external coordinate system according to the pre-calibrated rigid body coordinate transformation relationship.

Description

Technical Field

[0001] This invention relates to the field of spatial three-dimensional coordinate measurement and positioning technology, specifically to a method for precise elevation measurement based on the fusion of a wMPS rotating laser scanning system and an RTK real-time dynamic positioning system. Background Technology

[0002] In the field of spatial positioning and three-dimensional coordinate measurement, rotating laser scanning measurement technology is widely used in engineering construction surveying, industrial positioning and spatial attitude measurement due to its large coverage, relatively simple structure and ability to perform continuous scanning operations.

[0003] Rotating laser scanning measurement technology, as an important spatial positioning method, has gained widespread attention due to its advantages such as large measurement coverage, relatively simple system structure, and ability to perform continuous automated scanning operations. Represented by the wMPS (workspace Measuring and Positioning System), it typically uses a rotating transmitting device to form a spatial scanning light plane, with the receiving end detecting the scanning signal and establishing spatial geometric constraints based on the scanning phase, thereby realizing the coordinate calculation of spatial points.

[0004] In existing technologies, there are two main types of implementations for wMPS systems. The first is a multi-transmitter angle intersection mode, which involves deploying at least two transmitters at known locations and calculating spatial three-dimensional coordinates through angle intersection at the same receiving point. This method has high system complexity and deployment costs. The second is a single-transmitter mode combined with a synchronization signal or synchronization light. In this mode, synchronization light or a periodic reference signal is used as the initialization reference for rotational scanning to determine the absolute phase of the scan. The receiver establishes a time reference by detecting the synchronization light signal and then combines it with the scanning light plane signal to complete the spatial coordinate calculation. However, in practical applications, the effective propagation distance of the synchronization light signal is limited and it is easily affected by factors such as obstruction, ambient light interference, and changes in equipment attitude. When the synchronization light signal cannot be received stably, the absolute phase of the rotational scan is difficult to determine, thus affecting the reliability and stability of the spatial coordinate calculation.

[0005] Patent CN105157687 discloses a method for measuring the position and attitude of dynamic objects based on wMPS. This method establishes a timing reference by synchronizing the rotation period of a laser transmitter with the internal crystal oscillator of the processor, and then uses data synchronization from multiple receivers to achieve pose measurement. This scheme employs a multi-receiver measurement and synchronization strategy, resulting in high system deployment complexity and cost. Furthermore, it uses an absolute phase measurement method, relying on a synchronization optical signal as a reference, leading to a limited effective measurement range and making it unsuitable for outdoor engineering environments, such as elevation measurement in automated paving.

[0006] On the other hand, Real-Time Kinematic (RTK) positioning technology from Global Navigation Satellite Systems can provide centimeter-level planar positioning accuracy and has been widely used in engineering construction and mobile surveying scenarios. However, due to the characteristics of satellite geometric distribution and the influence of atmospheric errors, the elevation direction measurement accuracy provided by RTK is usually significantly lower than its planar accuracy. Therefore, in application scenarios requiring high-precision elevation measurement, relying solely on the RTK system is often insufficient to meet the requirements.

[0007] Patent CN1928586A discloses an altitude measurement device and method based on RTK-GPS technology. The method essentially involves RTK measurement between a base station and a rover, followed by altitude conversion. The specification also provides accuracy indicators: RTK horizontal accuracy of 2cm + 1ppm and vertical accuracy of 3cm + 1ppm. However, because GNSS vertical accuracy is more sensitive to satellite geometry and atmospheric residuals, vertical accuracy is often lower than horizontal accuracy. Therefore, in scenarios requiring millimeter-level accuracy in elevation smoothness, such as high-grade road paving, relying solely on an RTK system is insufficient to meet measurement needs.

[0008] Therefore, the use of a single wMPS rotating laser emitting device to achieve real-time and precise calculation of spatial point elevation without relying on synchronization optical signals, combined with coordinate information provided by RTK, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] This invention addresses the shortcomings of existing technologies by providing a precision elevation measurement method based on the fusion of wMPS and RTK real-time dynamic positioning systems. This method, using only a single wMPS rotating laser emitting device, acquires the phase difference parameter between two scanning light planes and combines it with the two-dimensional coordinate information provided by RTK. This allows for the construction of spatial constraint relationships without relying on a synchronous light reference signal, eliminating absolute phase variables during rotating scanning, and thus enabling the calculation of the elevation and three-dimensional spatial coordinates of the point to be measured.

[0010] The first aspect of this invention is to provide a method for precise elevation measurement based on the fusion of wMPS and RTK real-time dynamic positioning systems, comprising: Step 1: Obtain the two-dimensional coordinates of the point to be measured in an external coordinate system. Using the pre-calibrated coordinate transformation relationship, transform the two-dimensional coordinates of the point to be measured to the wMPS transmitter coordinate system to obtain the two-dimensional coordinates (x,y) of the point to be measured in the wMPS transmitter coordinate system. Step 2: Arrange a single rotating laser emitter and a photodetector at the point to be measured in the measurement space; the rotating laser emitter rotates at a constant angular velocity and generates at least two scanning light planes with a fixed spatial angle; the photodetector receives the signals of the scanning light planes, and calculates the relative phase difference when the at least two scanning light planes pass over the point to be measured based on the scanning period of the rotating laser emitter. ; Step 3: Based on the relative phase difference obtained in Step 2 and the scanning parameters of the rotating laser emitting device, establish the spatial constraint relationship between the spatial coordinates of the point to be measured and the rotating scanning phase, and construct the instantaneous light plane constraint equation; Step 4: Using the two-dimensional planar coordinates (x, y) in the wMPS transmitter coordinate system obtained in Step 1 as known quantities, set the elevation variable of the point to be measured in the wMPS transmitter coordinate system as an unknown single-degree-of-freedom elevation variable z, and set the coordinates of the point to be measured... Substituting the instantaneous light plane constraint equation established in step three, we obtain a system of linear equations with the single-degree-of-freedom elevation variable z and the absolute phase t of the rotational scan as variables; Step 5: Transform the system of equations obtained in Step 4 to obtain a linear expression for the intermediate variable of the rotating scan phase, where the intermediate variable of the rotating scan phase is the absolute phase of the rotating scan. t Trigonometric functions; Step Six: Substitute the intermediate variable of the rotating scanning phase obtained in Step Five into the trigonometric identity constraint, construct and solve the nonlinear equation about the single-degree-of-freedom elevation variable z, and obtain the elevation variable of the point to be measured in the wMPS transmitter station coordinate system. Step 7: Combine the elevation variable obtained in Step 6 with the two-dimensional planar coordinates (x, y) in the wMPS transmitter coordinate system obtained in Step 1 to obtain the three-dimensional coordinates of the point to be measured in the wMPS transmitter coordinate system; then, according to the pre-calibrated rigid body coordinate transformation relationship between the wMPS coordinate system and the external coordinate system, output the three-dimensional coordinates in the external coordinate system.

[0011] Furthermore, in step one, the planar two-dimensional coordinates of the point to be measured in the external coordinate system are obtained by at least one of an RTK real-time dynamic positioning system, an ultra-wideband UWB positioning system, or a lidar SLAM system.

[0012] Preferably, the RTK real-time dynamic positioning system is a GNSS carrier phase differential positioning system, used to provide centimeter-level planar positioning data.

[0013] Furthermore, in step two, the relative phase difference when at least two scanning light planes sweep across the point to be measured is calculated. include: The first moment when the two scanning light planes sequentially sweep across the test point is obtained by the photodetector. With the second time Calculate the time difference of arrival of the two scanning light planes. ; Construct a periodic ratio form to represent the time difference. The period ratio parameter is obtained by comparing it with the scanning period of the rotating laser emitting device. : ; Where T is the scanning period of the rotating laser emitting device; The period ratio parameter δ is converted into the relative angle difference Δ when the scanning light plane sweeps across the point to be measured, which is the relative phase difference.

[0014] Furthermore, the spatial constraint relationship in step three is a point-to-surface algebraic constraint relationship between the point to be measured and the rotating light plane.

[0015] Furthermore, the instantaneous light plane constraint equation in step three is expressed as:

[0016]

[0017] in, and The first laser plane at time t and the second laser plane at time t are respectively. The unit normal vector at time t.

[0018] Furthermore, in step five, let: The linear equations obtained in step four are rearranged into a linear equation system concerning the intermediate variables u and v of the rotating scan phase, and the expressions for u(z) and v(z) are obtained by solving the system.

[0019] Furthermore, in step six, according to the trigonometric identities: Substitute the u(z) and v(z) obtained in step five into the equation to construct a single-degree-of-freedom elevation variable. z Nonlinear equations:

[0020] The nonlinear equation is solved by numerical iteration, where the initial values ​​for iteration are set by the elevation data obtained from the initial measurement in step one.

[0021] A second aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described precision elevation measurement method.

[0022] The beneficial effects of this invention are as follows: The aforementioned high-precision elevation measurement method can achieve spatial elevation coordinate calculation under the condition of a single rotating laser emitting device, reducing the complexity and cost of system deployment; Elevation calculation can be completed without relying on the synchronous optical reference signal of the wMPS system, which improves the stability and adaptability of the system in complex environments and increases the measurement range of the system. In the preferred embodiment, the wMPS rotating laser scanning system and the RTK real-time dynamic positioning system are integrated, which greatly improves the accuracy of elevation measurement. Moreover, the method is applicable to dynamic measurement scenarios and has good scalability and fusion capabilities. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the elevation precision measurement method based on the fusion of wMPS and RTK real-time dynamic positioning systems described in Example 1; Figure 2 This is a schematic diagram of two scanning light planes passing through a photoelectric receiver in the elevation precision measurement method based on the fusion of wMPS and RTK real-time dynamic positioning systems described in Example 1.

[0024] Wherein, 1: rotating laser emitting device; 2: photoelectric receiver; 3: first laser plane; 4: second laser plane. Detailed Implementation

[0025] To make the objectives, technical solutions, beneficial effects, and significant advancements of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings provided in the examples of the present invention. Obviously, all the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this application, unless otherwise expressly specified and limited, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more; unless otherwise specified or explained, the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] Example 1 like Figure 1As shown, a method for precise elevation measurement based on the fusion of wMPS and RTK real-time dynamic positioning systems includes: Step 1: Obtain the two-dimensional planar coordinates of the point to be measured in the RTK coordinate system and convert them to two-dimensional planar coordinates in the wMPS transmitter station coordinate system.

[0028] First, the two-dimensional coordinates of the point to be measured in the RTK coordinate system are obtained using the RTK system, denoted as . .

[0029] The RTK system is a real-time dynamic positioning system based on the GNSS carrier phase differential principle, used to output high-precision planar positioning data of the point to be measured in the engineering coordinate system or the geodetic projection coordinate system.

[0030] In this embodiment, the wMPS rotating laser emitting device 1 establishes an independent local coordinate system for the emitting station. Its origin is located at the center of the rotation axis of the rotating laser emitting device 1, the Z-axis is along the direction of the rotation axis, the X-axis is consistent with the direction of the intersection line of the initial scanning light plane, and the Y-axis is determined according to the right-hand rule.

[0031] Since the RTK coordinate system and the wMPS transmitter station coordinate system are two different coordinate systems, there is a pre-calibrated rigid body coordinate transformation relationship between them. Through this transformation relationship, the two-dimensional planar coordinates of the point to be measured in the RTK coordinate system can be determined. Transform to a two-dimensional planar coordinate system in the wMPS transmitter station coordinate system, denoted as (x, y).

[0032] In this embodiment, (x, y) represents the planar coordinate components of the point to be measured in the wMPS transmitter coordinate system, and the elevation variable z is an unknown. Subsequent spatial constraints and the optical plane equations are all established and solved in the wMPS transmitter coordinate system.

[0033] Step 2: Obtain the phase difference parameters like Figure 2 As shown, a single rotating laser emitter 1 and a photoelectric receiver 2 are arranged in the measurement space. The photoelectric receiver 2 is placed at the point to be measured and is used to detect the signal times when the two scanning light planes sweep across the point to be measured, denoted as _____. and .

[0034] The rotating laser emitting device 1 generates at least one synchronization light pulse and two scanning laser plane pulses in each emission cycle, forming two scanning light planes with a fixed spatial angle relationship, namely the first laser plane 3 and the second laser plane 4. The rotating laser emitting device 1 operates at a constant angular velocity. Perform a rotational scan, with a scan cycle of: (1) When the two scanning light planes generated by the rotating laser emitting device 1 sequentially sweep across the photodetector 2, the photodetector 2 records the arrival times of the two laser planes. and ; Construct phase difference parameters and calculate the time difference between the arrival of the first laser plane 3 and the second laser plane 4. : (2) Construct a periodic ratio form to represent the time difference. The period ratio parameter is obtained by comparing it with the scan period. : (3) The obtained period ratio parameter Converted into the relative angle difference when the first laser plane 3 and the second laser plane 4 sweep across the point to be measured. for: (4) The relative angle difference The relative phase difference between the two scanning light planes sweeping across the point to be measured.

[0035] Step 3: Based on the relative phase difference obtained in Step 2 and the scanning parameters of the rotating laser emitting device, establish the instantaneous equation of the rotating optical plane.

[0036] S31: Establish the spatial equations for the two scanning light planes at the initial moment. In the local coordinate system of the transmitting station of the rotating laser emitter, let the spatial equations of the two scanning light planes at the initial moment be:

[0037] (5) in:

[0038] (6) Where p is a coordinate vector , and These are the unit normal vectors of the first laser plane 3 and the second laser plane 4 at the initial moment, respectively. and is the constant term in the plane equation.

[0039] S32: Let the absolute phase of the rotation scan be t, then the rotation matrix... for: (7) Since photodetector 2 is swept by the first laser plane and the second laser plane successively at the point to be measured, based on the relative angle difference obtained in step two... Then, at the current moment, the normal vectors of the first laser plane 3 and the second laser plane 4 are respectively:

[0040] (8) Substituting the obtained normal vector into equation (5), the corresponding instantaneous light plane constraint equation is obtained as follows:

[0041] (9) Step 4: Introduce single-degree-of-freedom variables Based on the two-dimensional planar coordinates (x, y) in the wMPS transmitter coordinate system obtained in step one, the three-dimensional coordinates of the point to be measured are expressed as follows:

[0042] Where z is the single-degree-of-freedom elevation variable to be solved, thus representing the spatial coordinates of the point to be measured as a single-degree-of-freedom variable along the vertical direction.

[0043] Will Substituting these equations into the instantaneous light plane constraint equation of equation (9), we can obtain the absolute phase of the rotating scan as shown in equation (10). t With single-degree-of-freedom elevation variables z Two equations:

[0044] (10) Thus, an absolute phase of the rotational scan is constructed. t A system of linear equations.

[0045] Step 5: Solve the system of linear equations obtained in Step 4 to obtain the expression for the intermediate variable of the rotating scan phase.

[0046] set up: ; Based on the rotation matrix expansion, the two-plane constraint equations can be rearranged to relate to the absolute phase of the rotation scan. t and single-degree-of-freedom elevation variables z The equation:

[0047] (11) The following system of linear equations is constructed regarding the intermediate variables u and v of the rotating scan phase: (12) Given that the determinant is nonzero, we use algebraic methods to solve for u(z) and v(z).

[0048] Step Six: Based on the trigonometric identities: (13) Substituting u(z) and v(z) obtained in step five into the above constraint (13), we construct a single-degree-of-freedom elevation variable. z Nonlinear equations: (14) Equation (14) represents the elevation variable with respect to only one degree of freedom. z The polynomial equation yields a result regarding the single-degree-of-freedom elevation variable. z The nonlinear equation.

[0049] The obtained single-degree-of-freedom elevation variables z The nonlinear equations are solved using a numerical iterative method, with the initial values ​​set based on low-precision elevation data obtained from RTK measurements. Through numerical iteration, the single-degree-of-freedom elevation variable that meets the preset requirements is obtained. z The numerical solution is the elevation variable z of the point to be measured in the wMPS transmitter station coordinate system.

[0050] Step 7: Combine the elevation variable z of the point to be measured in the wMPS transmitter coordinate system obtained in Step 6 with the two-dimensional planar coordinates (x, y) of the wMPS transmitter coordinate system obtained in Step 1 to form the three-dimensional coordinates (x, y, z) of the point to be measured in the wMPS transmitter coordinate system.

[0051] By utilizing the pre-calibrated rigid body coordinate transformation relationship between the wMPS coordinate system and the RTK coordinate system, the three-dimensional coordinates of the point to be measured are transformed to the RTK coordinate system, and the final three-dimensional spatial coordinates are output.

[0052] Once the external parameters between the two coordinate systems have been calibrated, the above transformation process is a fixed linear rigid body transformation process, and this step does not involve solving for new unknowns.

[0053] Step 8: Set a threshold to verify the validity of the solution. When the determinant of the above linear equation system (12) approaches zero, it indicates constraint degradation. A threshold is set to determine whether the solution is valid. This invention does not specifically limit the degradation determination method.

[0054] The above nonlinear equations may result in positive and negative roots for the elevation solution due to the periodicity or quadratic structure of the trigonometric functions. Initial value constraints are applied based on the approximate range of the elevation to select the correct and unique solution.

[0055] Thus, the elevation coordinates of the point to be measured can be calculated using only a single rotating laser emitting device and phase difference parameters.

[0056] Example 2 A method for precise elevation measurement based on the fusion of wMPS and RTK real-time dynamic positioning systems is disclosed. The measurement method is essentially the same as in Example 1, except that the two-dimensional planar coordinates are obtained using UWB (Ultra-Wideband) in step one. Specifically, it includes: Three UWB base stations with known coordinates are set up in the measurement area to form a positioning network covering the area to be measured. A UWB tag is configured for each point to be measured. All base stations and tags are synchronized in time and unified to the preset UWB system coordinate system. The tag transmits a UWB pulse signal, and each base station receives the signal. By measuring the signal's flight time, the distance from the tag to each base station is calculated. Using the known base station coordinates and the measured distance, the planar two-dimensional coordinate values ​​in the UWB system coordinate system are obtained; then, these values ​​are converted into planar two-dimensional coordinates in the wMPS transmitter station coordinate system.

[0057] Of course, depending on the specific circumstances, existing lidar systems can also be used to obtain the two-dimensional planar coordinates of the point to be measured in the external coordinate system.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for precise elevation measurement based on the fusion of wMPS and RTK real-time dynamic positioning systems, characterized in that, include: Step 1: Obtain the two-dimensional coordinates of the point to be measured in an external coordinate system. Using the pre-calibrated coordinate transformation relationship, transform the two-dimensional coordinates of the point to be measured to the wMPS transmitter coordinate system to obtain the two-dimensional coordinates (x,y) of the point to be measured in the wMPS transmitter coordinate system. Step 2: Arrange a single rotating laser emitter (1) and a photodetector (2) at the point to be measured in the measurement space; the rotating laser emitter (1) rotates at a constant angular velocity and generates at least two scanning light planes with a fixed spatial angle; the photodetector (2) receives the scanning light plane signals and calculates the relative phase difference when the at least two scanning light planes sweep across the point to be measured according to the scanning cycle of the rotating laser emitter (1). ; Step 3: Based on the relative phase difference obtained in Step 2 and the scanning parameters of the rotating laser emitting device (1), establish the spatial constraint relationship between the spatial coordinates of the point to be measured and the rotating scanning phase, and construct the instantaneous light plane constraint equation; Step 4: Using the two-dimensional planar coordinates (x, y) in the wMPS transmitter coordinate system obtained in Step 1 as known quantities, set the elevation variable of the point to be measured in the wMPS transmitter coordinate system as an unknown single-degree-of-freedom elevation variable z, and set the coordinates of the point to be measured... Substituting the instantaneous light plane constraint equation established in step three, we obtain a system of linear equations with the single-degree-of-freedom elevation variable z and the absolute phase t of the rotational scan as variables; Step 5: Transform the system of equations obtained in Step 4 to obtain a linear expression for the intermediate variable of the rotating scan phase, where the intermediate variable of the rotating scan phase is the absolute phase of the rotating scan. t Trigonometric functions; Step Six: Substitute the intermediate variable of the rotating scanning phase obtained in Step Five into the trigonometric identity constraint, construct and solve the nonlinear equation about the single-degree-of-freedom elevation variable z, and obtain the elevation variable of the point to be measured in the wMPS transmitter station coordinate system. Step 7: Combine the elevation variable obtained in Step 6 with the two-dimensional planar coordinates (x, y) in the wMPS transmitter coordinate system obtained in Step 1 to obtain the three-dimensional coordinates of the point to be measured in the wMPS transmitter coordinate system; then, according to the pre-calibrated rigid body coordinate transformation relationship between the wMPS coordinate system and the external coordinate system, output the three-dimensional coordinates in the external coordinate system.

2. The method for precise elevation measurement according to claim 1, characterized in that, In step one, the two-dimensional planar coordinates of the point to be measured in the external coordinate system are obtained by at least one of the following: RTK real-time dynamic positioning system, ultra-wideband UWB positioning system, or lidar SLAM system.

3. The method for precise elevation measurement according to claim 2, characterized in that, In step one, the RTK real-time dynamic positioning system is a GNSS carrier phase differential positioning system, used to provide centimeter-level planar positioning data.

4. The method for precise elevation measurement according to claim 1, characterized in that, In step two, the relative phase difference when at least two scanning light planes sweep across the test point is calculated. include: The first moment when the two scanning light planes sequentially sweep across the test point is obtained by the photodetector. With the second time Calculate the time difference of arrival of the two scanning light planes. ; Construct a periodic ratio form to represent the time difference. The period ratio parameter is obtained by comparing it with the scanning period of the rotating laser emitting device (1). : ； Where T is the scanning period of the rotating laser emitting device 1; The period ratio parameter δ is converted into the relative angle difference Δ when the scanning light plane sweeps across the point to be measured, which is the relative phase difference.

5. The method for precise elevation measurement according to claim 1, characterized in that, In step three, the spatial constraint relationship is the point-to-surface algebraic constraint relationship between the point to be measured and the rotating light plane.

6. The method for precise elevation measurement according to claim 1, characterized in that, The instantaneous light plane constraint equation in step three is expressed as follows: in, and The first laser plane (3) at time t and the second laser plane (4) at time t are respectively. The unit normal vector at time t.

7. The method for precise elevation measurement according to claim 1, characterized in that, In step five, let: ; The linear equations obtained in step four are rearranged into a linear equation system concerning the intermediate variables u and v of the rotating scan phase, and the expressions for u(z) and v(z) are obtained by solving the system.

8. The method for precise elevation measurement according to claim 1, characterized in that, In step six, according to the trigonometric identities: Substitute the u(z) and v(z) obtained in step five into the equation to construct a single-degree-of-freedom elevation variable. z Nonlinear equations: The nonlinear equation is solved by numerical iteration, where the initial values ​​for iteration are set by the elevation data obtained during the initial measurement in step one.

9. A computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of the elevation precision measurement method as described in any one of claims 1-8.

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