High-precision reference pile space relative position stability detection method

Abstract

The invention discloses a high-precision reference pile space relative position stability detection method, which comprises the following steps of: limiting the maximum length of the measurement distance of a laser tracker by adopting a free station setting measurement method according to the layout and distribution condition of the existing reference pile, determining the coordinate measurement error of the laser tracker, and determining the stability of the reference pile space relative position. Performing three-time space coordinate measurement on each pair of adjacent reference piles, performing error analysis on results, and determining whether three-time coordinate measurement results meet requirements or not according to error analysis results; if the requirement is not met, re-measuring; if the requirement is met, taking the average value of the three spatial distance values of the reference pile as a final value; determining a reference pile space distance measurement error according to the selected measurement method, the measurement instrument and the measurement environment; and based on the theoretical design value of the space distance of the adjacent reference piles, the final value of the space distance obtained through three times of measurement and calculation and the measurement error of the space distance of the reference piles, the stability of the space relative position of the reference piles is judged.

Description

Technical Field

[0001] The present invention belongs to the field of measurement technology, mainly relates to laser tracker measurement technology, and specifically relates to a method for detecting the spatial relative position stability of a rocket sled slide rail reference pile based on a laser tracker, which can be used for high-precision spatial relative position stability detection of three-dimensional control points within a smaller range. Background Art

[0002] High-precision slide rails are important infrastructure to ensure the success of rocket sled tests. The benchmark for measuring and adjusting the smoothness of the slide rails is the benchmark piles located next to the main track. Since the benchmark piles are too close to the track, they are inevitably affected by the rocket sled test. In addition, engineering construction and foundation settlement may cause changes in the spatial position of each benchmark pile, which will ultimately have an adverse effect on the track smoothness measurement and adjustment work.

[0003] In the prior art, the control network for the benchmark pile measurement of the rocket sled track project uses GNSS networking measurement. By jointly measuring high-level control points, the three-dimensional spatial coordinates of each benchmark pile in a unified spatial coordinate system are obtained through long-term, multi-period GNSS relative positioning observation and solution; this process requires a large number of high-precision GNSS receivers to work together and takes a long time to complete. At present, the field test of the rocket sled track is tightly arranged, and the efficiency of monitoring the stability of the control points of the benchmark piles by relying on the GNSS networking measurement method is low. Summary of the invention

[0004] The purpose of the present invention is to provide a high-precision reference pile spatial relative position stability detection method to solve the adverse effect of the spatial position change of the existing rocket sled reference pile on the measurement accuracy of track straightness.

[0005] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0006] A high-precision reference pile spatial relative position stability detection method, comprising:

[0007] According to the layout and distribution of existing benchmark piles, the free station measurement method is adopted to limit the maximum length of the measurement distance of the laser tracker, determine the coordinate measurement error of the laser tracker, and make the angle between the laser tracker and the adjacent benchmark piles to be measured within the preset angle range, and perform three spatial coordinate measurements on each pair of adjacent benchmark piles;

[0008] Based on the error analysis of the three-dimensional coordinate measurement results of adjacent reference piles by the laser tracker, determine whether the three-dimensional coordinate measurement results meet the requirements according to the error analysis results; if not, re-measure; if it meets the requirements, take the average of the three-dimensional distance values ​​of the reference piles as the final value;

[0009] Determine the measurement error of the reference pile space distance according to the selected measurement method, measurement instrument and measurement environment;

[0010] The stability of the relative spatial positions of the reference piles is determined based on the theoretical design value of the spatial distance between adjacent reference piles, the final value of the spatial distance calculated by three measurements, and the measurement error of the spatial distance between the reference piles.

[0011] Furthermore, the coordinate measurement error of the laser tracker is expressed as m0=±(15+6L) μm; L is the interval of the reference piles.

[0012] Furthermore, the preset angle range of the included angle between the laser tracker and the adjacent reference piles is 30° to 150°, and the maximum length of the measurement distance of the laser tracker is limited within L / 2.

[0013] Furthermore, the error analysis of the three-dimensional coordinate measurement results of adjacent reference piles based on the laser tracker is performed, and whether the three-dimensional coordinate measurement results meet the requirements is determined according to the error analysis results, including:

[0014] According to the spatial coordinate values ​​obtained by measurement, the spatial distance between adjacent benchmark piles is calculated using the following formula:

[0015]

[0016] In the above formula, (x a ,y a ,z a ),(x b ,y b ,z b ) are the spatial coordinate measurement values ​​of the adjacent benchmark piles A and B measured for the first time, S1 is the spatial distance value of the benchmark piles A and B measured for the first time, Δx, Δy, Δz are the differences between the benchmark piles A and B in the x, y, and z coordinate axis directions, respectively, m S0 is the mean error of a spatial distance measurement, m Δx 、m Δy 、m Δz are the mean error of the coordinate difference of the laser tracker in the x, y, and z directions respectively;

[0017] Use the same method to calculate the second and third measured spatial distance values ​​S2 and S3 of the benchmark piles A and B, and analyze whether the three measured spatial distance values ​​of the benchmark piles meet the measurement accuracy:

[0018] S1, S2, S3 and their maximum and minimum values ​​S max , S min For equal precision measurements, the following error relationship exists:

[0019]

[0020] In the above formula, m0 represents the coordinate measurement error of the laser tracker, m x ,m y ,m z is the mean error of the coordinate measurement values ​​of the laser tracker in the x, y, and z directions, is the mean error of the spatial distance value calculated from a measurement, is the mean error between the maximum and minimum values ​​of the spatial distance measurement;

[0021] According to the error propagation law:

[0022]

[0023] m Δx 、m Δy 、m Δz are the mean errors of the coordinate differences of the instrument in the x, y, and z directions, from which m can be obtained s较差 ;

[0024] If the judgment satisfies |S 较差 |≤|2m S较差 |, at this time, the measurement results of the three-dimensional distance values ​​of the adjacent reference piles meet the measurement accuracy requirements, and the average value of the three-dimensional distance values ​​S1, S2, and S3 is taken as the final value S′ of the distance measurement between the two reference piles;

[0025] If the difference between them does not meet the requirements, repeat the measurement three times.

[0026] Furthermore, the determining of the reference pile spatial distance measurement error according to the selected measurement method, measurement instrument and measurement environment includes:

[0027] The instrument measurement error introduced by using a laser tracker for distance measurement is m0 represents the coordinate measurement error of the laser tracker; the target ball installation error is m2 = ±0.10mm; the measurement error caused by fluctuations in ambient temperature, airflow, etc. is m3 = ±0.017L;

[0028] The measurement error of the reference pile spatial distance is

[0029]

[0030] Further, the stability of the relative spatial position of the reference piles is judged based on the theoretical design value of the spatial distance between adjacent reference piles, the final value of the spatial distance calculated by three measurements, and the measurement error of the spatial distance between the reference piles, including:

[0031] For two adjacent reference piles, the theoretical design value of the spatial distance between the two reference piles is known to be S0 before detection, and the final value obtained by detection measurement is S′, and ΔS is the difference between the two:

[0032] ΔS=S′-S0

[0033] Take 2 times the mean error as the limit error as the comparative analysis condition, that is, -2m 检测 ≤ΔS≤+2m 检测 , determine the stability of the benchmark pile:

[0034] If ΔS does not exceed the tolerance, the spatial position of the reference pile is considered to be stable; if ΔS exceeds the tolerance, it is preliminarily considered that the spatial relative position of the adjacent reference piles has changed, and it can be determined that the relative position of this pair of reference piles is unstable.

[0035] Furthermore, in the case where the relative positions of the reference piles are unstable, other reference piles adjacent to the two reference piles should be tested under the same or similar meteorological environment to determine the unstable reference pile; the unstable reference pile should be avoided in the future.

[0036] Compared with the prior art, the present invention has the following technical features:

[0037] The method of the present invention has high accuracy in measuring the spatial coordinates of the reference pile, a simple data processing method, no need for separate leveling or GNSS networking measurement, and a free station setting method, which can be applicable to on-site measurement of precision engineering or special equipment with complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the distribution of benchmark piles;

[0039] Figure 2 Schematic diagram of laser tracker station measurement;

[0040] Figure 3 Schematic diagram of laser tracker target ball installation method. DETAILED DESCRIPTION

[0041] In order to solve the problems existing in the prior art, a laser tracker was used to perform high-precision measurement of the spatial straight-line distance between adjacent reference piles during the straightness detection of the slide rail. The measured spatial distance was compared with the design value, and the internal conformity accuracy of the spatial coordinates of the reference piles and the stability of their relative spatial position were analyzed based on this.

[0042] Step 1: According to the existing distribution of reference piles with one every L meters, a free station measurement method is used to limit the maximum length of the laser tracker's measurement distance to within L / 2, determine the coordinate measurement error m0 of the laser tracker, and make the angle between the instrument and the adjacent reference piles to be measured within the preset angle range, and perform three spatial coordinate measurements on each pair of adjacent reference piles.

[0043] Taking the Leica AT403 laser tracker as an example, its maximum measurement distance can reach 160m, with high measurement accuracy. Its nominal accuracy is shown in Table 1:

[0044] Table 1 AT403 laser tracker nominal accuracy

[0045]

[0046]

[0047] When the distance is L (unit: m), the coordinate measurement error of the instrument is:

[0048] m0=±(15+6L)μm (1)

[0049] m0 is the coordinate measurement error of the measuring instrument, which is related to the instrument accuracy and the measurement distance. In order to improve the detection accuracy of the benchmark pile in this scheme, the measurement distance is controlled at about 30 meters. At this time, the coordinate measurement accuracy calculated according to Formula 1 is m0 = ±0.195mm.

[0050] After leveling the instrument and placing the target reflective prism, the laser tracker is used to measure the three-dimensional spatial coordinate values ​​of adjacent reference piles in the target area to obtain the spatial coordinates A1 (x a1 ,y a1 ,z a1 )、B1(x b1 ,y b1 ,z b1 ), then change the position of the instrument and repeat the above measurements. Each benchmark pile should be measured at least 3 times to reduce accidental errors.

[0051] For this scheme, the location selection of the instrument is:

[0052] The installation location of the laser tracker is selected according to the distribution of the benchmark piles. Generally, a hard ground with a stable foundation is selected as the installation location of the laser tracker, and areas with large changes in climate and environment such as humidity, temperature, wind speed, and ground vibration and instability are avoided as much as possible. In order to offset the influence of atmospheric refraction on measurement accuracy, the instrument is generally installed in the middle of adjacent benchmark piles, and the angle (inner angle) formed by benchmark pile A-instrument-benchmark pile B should be kept between 30° and 150° as much as possible. This implementation plan is to detect several benchmark piles uniformly distributed in a line one by one. If the benchmark piles are distributed in a network, this method can measure multiple pairs of benchmark piles A1, B1, C1, D1... at one measuring station, and the detection efficiency can be higher.

[0053] Step 2: Perform error analysis on the three-dimensional coordinate measurement results of adjacent reference piles based on the laser tracker, and determine whether the three-dimensional coordinate measurement results meet the requirements according to the error analysis results; if not, return to step 1 and re-measure; if it meets the requirements, take the average of the three-dimensional distance values ​​of the reference piles as the final value, as described below:

[0054] After the laser tracker is set up as required in step 1, the spatial distance between adjacent reference piles is calculated using formula 2 based on the spatial coordinate values ​​obtained by measurement.

[0055]

[0056] In the above formula 2, (x a ,y a ,z a ),(x b ,y b ,z b ) are the spatial coordinate measurement values ​​of the adjacent benchmark piles A and B measured for the first time, S1 is the spatial distance value of the benchmark piles A and B measured for the first time, Δx, Δy, Δz are the differences between the benchmark piles A and B in the x, y, and z coordinate axis directions, respectively, m S0 is the mean error of a spatial distance measurement, m Δx 、m Δy 、m Δz are the mean errors of the coordinate differences of the laser tracker in the x, y, and z directions, respectively, and are determined by formula (6).

[0057] Use the same method to calculate the second and third measured spatial distance values ​​S2 and S3 of the benchmark piles A and B, and analyze whether the three measured spatial distance values ​​of the benchmark piles meet the measurement accuracy:

[0058] S1, S2, S3 and their maximum and minimum values ​​S max , S minFor equal-precision measurement values, assuming that the laser tracker has the same coordinate measurement accuracy for the x, y, and z directions (the observation accuracy in the z coordinate direction is generally slightly lower in actual measurements), and ignoring other error sources, the following error relationship exists:

[0059]

[0060] In the above formula 5, m x ,m y ,m z is the mean error of the coordinate measurement values ​​of the laser tracker in the x, y, and z directions, is the mean error of the spatial distance value calculated from a measurement, is the mean error between the maximum and minimum values ​​of the spatial distance measurement.

[0061] Combining the above equation 2, we can get the error propagation law:

[0062]

[0063] m Δx 、m Δy 、m Δz are the mean errors of the coordinate differences of the instrument in the x, y, and z directions, and thus we can get

[0064] In a measurement environment without significant changes in light, temperature, humidity, and vibration, the multiple measurements in step 1 can be considered to be completed in a relatively short period of time, without considering the adverse effects of environmental changes on the measurement accuracy of the laser tracker. The worst maximum values ​​S of the three spatial distance values ​​S1, S2, and S3 are 较差 Should be less than 2 times of the error (in this case S 较差 Only contains accidental errors, the confidence interval is 95.5%), there is the relationship shown in the following formula 3 and formula 4:

[0065]

[0066] |S 较差 |=|S max -S min | (6)

[0067] In the above formula 3 and formula 4, S max , S min The maximum and minimum values ​​of the spatial distance values ​​S1, S2, and S3 calculated from three measurements, For S 较差 The mean error of .

[0068] Therefore, in seeking After that, if the At this time, if the measurement results of the three-dimensional distance values ​​of the adjacent reference piles meet the measurement accuracy requirements, the average value of the three-dimensional distance values ​​S1, S2, and S3 is taken as the final value S′ of the distance measurement between the two reference piles;

[0069] If the difference between them does not meet the requirements, a stable measurement environment with small changes in light, temperature, humidity and wind speed should be selected, and the measurement should be repeated three times according to step 1.

[0070] Step 3: Determine the measurement error of the reference pile space distance based on the selected measurement method, measurement instrument and measurement environment.

[0071] 1) Measurement error of laser tracker

[0072] According to the layout of the reference piles of the rocket sled rail, it can be seen that the control points of the reference piles are distributed in an approximately linear extension shape, and Δx, Δz ≤ 10mm, Δy ≈ 60000mm, so the coordinate deviations of adjacent control piles have the relationship shown in the following formula 7:

[0073] Δx, Δz<<Δy (7)

[0074] Combining equations (2), (6) and (7) above, we can obtain:

[0075]

[0076] If ignored The small influence of , we get:

[0077]

[0078] From the above formula 8, it can be seen that, without considering the influence of other factors such as system error and gross error, the accuracy of S0 is proportional to the coordinate measurement accuracy of the laser tracker. When the reference piles to be detected are distributed in a grid, the ratio of Δx, Δy, and Δz does not have the relationship shown in formula 7. The impact cannot be ignored.

[0079] The instrument measurement error introduced when using a laser tracker for distance measurement is:

[0080]

[0081] According to the nominal accuracy m0 of the instrument in this scheme, m1=0.275mm is calculated. At this time, m1 is the detection error introduced by the limitation of the instrument measurement accuracy during the entire detection process of this scheme.

[0082] 2) Installation error of target prism on the reference pile

[0083] When installing the reflective target ball on the reference pile, due to the processing errors of the forced centering plate and the target ball tooling, the target ball installation error is introduced during the measurement process, such as Figure 3 According to the machining accuracy of the machine and the measurement experience, the influence of the target ball installation error on the distance measurement observation value is generally controlled within m2 = ± 0.10 mm.

[0084] 3) Sources of error caused by changes in environmental factors

[0085] The measurement error caused by fluctuations in ambient temperature, airflow, etc. is calculated according to the Edlund formula as follows:

[0086] m3=±0.017L (1)

[0087] In the above formula, L is the measurement distance length (unit: meter). When the maximum spatial distance is 30 meters, the error introduced by the measurement is: m3 = ±0.51mm.

[0088] Comprehensive analysis of the above error sources shows that environmental factors have the most obvious impact on the measurement accuracy of the laser tracker. Considering the influence of complex factors such as the environment, the spatial distance measurement errors of the benchmark piles are:

[0089]

[0090] Step 4: judging the stability of the relative spatial position of the reference piles based on the theoretical design value of the spatial distance between adjacent reference piles, the final value of the spatial distance calculated by three measurements, and the measurement error of the spatial distance between the reference piles.

[0091] For two adjacent reference piles, the theoretical design value of the spatial distance between the two reference piles is known to be S0 before detection, and the final value obtained by detection measurement is S′, and ΔS is the difference between the two:

[0092] ΔS=S′-S0

[0093] Take 2 times the mean error as the limit error as the comparative analysis condition, that is, -2m 检测 ≤ΔS≤+2m 检测 , determine the stability of the benchmark pile:

[0094] If ΔS does not exceed the tolerance, excluding the simultaneous position changes of the two reference piles, the spatial position of the above reference piles can be considered stable;

[0095] If ΔS exceeds the limit, it is preliminarily considered that the relative spatial position of the adjacent benchmark piles has changed, and it can be determined that the relative position of this pair of benchmark piles is unstable, that is, one or both of the benchmark piles are unstable; under similar meteorological conditions, the other benchmark piles adjacent to these two benchmark piles should be tested according to the above method to determine the unstable benchmark pile; for unstable benchmark piles, they should be avoided from use in the future, and the coordinates should be remeasured and updated in time.

[0096] Example:

[0097] Before testing a certain type of rocket sled, technicians conducted high-precision measurements of the spatial coordinates of the reference piles of the rocket sled track. The statistical calculation of the spatial straight lines of adjacent reference piles is shown in Table 1 below.

[0098] Table 1 The spatial distance calculated by each measuring station of adjacent benchmark piles is poor

[0099]

[0100] Considering the changes in the measurement environment, the mean error of the spatial distance difference between the first, second and third stations in each measurement area is calculated as: The worst maximum value in the above table is: 1.12mm<2m 较差 , indicating that the spatial distance results calculated from the three observation values ​​of each side segment meet the requirements, and no other gross errors occur during the measurement process, so the next step of calculation and analysis can be carried out.

[0101] Table 2 Measured values ​​of spatial distances between adjacent benchmark piles Worse than the design value

[0102]

[0103] The maximum difference in the above table is: |-0.57mm|<2·m s , excluding the case where the two reference piles change their positions at the same time, it is considered that the spatial positions of the above Z31~Z16 multiple reference piles are stable and can be used as the benchmark for track measurement and adjustment.

[0104] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for detecting the spatial relative position stability of a high-precision reference pile, characterized in that: include: According to the layout and distribution of existing benchmark piles, the free station measurement method is adopted to limit the maximum length of the measurement distance of the laser tracker, determine the coordinate measurement error of the laser tracker, and make the angle between the laser tracker and the adjacent benchmark piles to be measured within the preset angle range, and perform three spatial coordinate measurements on each pair of adjacent benchmark piles; Based on the error analysis of the three-dimensional coordinate measurement results of adjacent reference piles by the laser tracker, it is determined whether the three-dimensional coordinate measurement results meet the requirements according to the error analysis results; If the requirements are not met, re-measure; if the requirements are met, the average of the three spatial distance values ​​of the benchmark pile is taken as the final value; Determine the measurement error of the reference pile space distance according to the selected measurement method, measurement instrument and measurement environment; The stability of the relative spatial positions of the reference piles is determined based on the theoretical design value of the spatial distance between adjacent reference piles, the final value of the spatial distance calculated by three measurements, and the measurement error of the spatial distance between the reference piles.

2. The method for detecting the spatial relative position stability of a high-precision reference pile according to claim 1, characterized in that: The coordinate measurement error of the laser tracker is expressed as m0=±(15+6L)μm; L is the interval of the reference piles.

3. The method for detecting the spatial relative position stability of a high-precision reference pile according to claim 1, characterized in that: The preset angle range of the included angle between the laser tracker and the adjacent reference piles is 30° to 150°, and the maximum length of the measurement distance of the laser tracker is limited to within L / 2.

4. The method for detecting the spatial relative position stability of a high-precision reference pile according to claim 1, characterized in that: The method of performing error analysis on the three-dimensional coordinate measurement results of adjacent reference piles based on the laser tracker and determining whether the three-dimensional coordinate measurement results meet the requirements according to the error analysis results includes: According to the spatial coordinate values ​​obtained by measurement, the spatial distance between adjacent benchmark piles is calculated using the following formula: In the above formula, (x a ,y a ,z a ),(x b ,y b ,z b ) are the spatial coordinate measurement values ​​of the adjacent benchmark piles A and B measured for the first time, S1 is the spatial distance value of the benchmark piles A and B measured for the first time, Δx, Δy, Δz are the differences between the benchmark piles A and B in the x, y, and z coordinate axis directions, respectively, m S0 is the mean error of a spatial distance measurement, m Δx 、m Δy 、m Δz are the mean error of the coordinate difference of the laser tracker in the x, y, and z directions respectively; Use the same method to calculate the second and third measured spatial distance values ​​S2 and S3 of the benchmark piles A and B, and analyze whether the three measured spatial distance values ​​of the benchmark piles meet the measurement accuracy: S1, S2, S3 and their maximum and minimum values ​​S max , S min For equal precision measurements, the following error relationship exists: In the above formula, m0 represents the coordinate measurement error of the laser tracker, m x ,m y ,m z is the mean error of the coordinate measurement values ​​of the laser tracker in the x, y, and z directions, is the mean error of the spatial distance value calculated from a measurement, is the mean error between the maximum and minimum values ​​of the spatial distance measurement; According to the error propagation law: m Δx 、m Δy 、m Δz are the mean errors of the coordinate differences of the instrument in the x, y, and z directions, and thus we can get If the judgment is satisfied At this time, if the measurement results of the three-dimensional distance values ​​of the adjacent reference piles meet the measurement accuracy requirements, the average value of the three-dimensional distance values ​​S1, S2, and S3 is taken as the final value S′ of the distance measurement between the two reference piles; If the difference between them does not meet the requirements, repeat the measurement three times.

5. The method for detecting the spatial relative position stability of a high-precision reference pile according to claim 1, characterized in that: Determining the reference pile spatial distance measurement error according to the selected measurement method, measurement instrument and measurement environment includes: The instrument measurement error introduced by using a laser tracker for distance measurement is m0 represents the coordinate measurement error of the laser tracker; the target ball installation error is m2 = ±0.10mm; the measurement error caused by fluctuations in ambient temperature, airflow, etc. is m3 = ±0.017L; The measurement error of the reference pile spatial distance is 6. The method for detecting the spatial relative position stability of a high-precision reference pile according to claim 1, characterized in that: The method of judging the stability of the relative spatial position of the reference piles based on the theoretical design value of the spatial distance between adjacent reference piles, the final value of the spatial distance calculated by three measurements, and the measurement error of the spatial distance between the reference piles includes: For two adjacent reference piles, the theoretical design value of the spatial distance between the two reference piles is known to be S0 before detection, and the final value obtained by detection measurement is S′, and ΔS is the difference between the two: ΔS=S′-S0 Take 2 times the mean error as the limit error as the comparative analysis condition, that is, -2m 检测 ≤ΔS≤+2m 检测 , determine the stability of the benchmark pile: If ΔS does not exceed the tolerance, the spatial position of the reference pile is considered to be stable; if ΔS exceeds the tolerance, it is preliminarily considered that the spatial relative position of the adjacent reference piles has changed, and it can be determined that the relative position of this pair of reference piles is unstable.

7. The method for detecting the spatial relative position stability of a high-precision reference pile according to claim 6, characterized in that: In the case where the relative position of the reference piles is unstable, the other reference piles adjacent to the two reference piles should be tested under the same or similar meteorological environment to determine the unstable reference pile; the unstable reference piles should be avoided in the future.

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