Vertical refraction determination using a Trimble S9 total station

2020 ◽  
Vol 954 (12) ◽  
pp. 2-9
Author(s):  
D.V. Dementiev ◽  
I.M. Zhukov ◽  
M.Y. Karavanov ◽  
I.I. Ranov ◽  
N.Yu. Litvinov
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulent Atmosphere ◽  
Measurement Accuracy ◽  
Dynamic Method ◽  
Experimental Studies ◽  
High Accuracy ◽  
Measuring Instruments ◽  
Total Station ◽  
The Real

Classical methods for determining refraction are based on Newton’s formulae for a statically stable atmosphere. However, they do not provide the required measurement accuracy due to random changes in refraction, caused by the influence of atmospheric turbulence. The aim of this work is to study the dynamic method for determining refraction in a turbulent atmosphere. The measurements were performed with a Trimble S9 total station. It was found out, that within a few seconds the angle of vertical refraction can change by dozens of arc seconds. To improve the accuracy of the results, it is necessary to determine the refraction instantly for a specific moment of observation and for a particular path, otherwise the obtained corrections will not correspond to the real angle of refraction. The introduction of a dynamic method for determining refraction requires more extensive experimental studies under various observation conditions. In the case of confirmation of the high accuracy of the dynamic method for determining the fraction, significant prospects open up for taking refraction into account and developing new more effective measuring instruments in a turbulent atmosphere.

scholarly journals Laser Interferometry of Turbulent Atmosphere

2012 ◽  
Vol 29 (3) ◽  
pp. 323-327
Author(s):  
Gennady Kaloshin ◽  
Igor Lukin
Keyword(s):  
Laser Beam ◽  
Atmospheric Turbulence ◽  
Turbulent Atmosphere ◽  
Random Media ◽  
Laser Interferometer ◽  
Theoretical Calculations ◽  
Laser Interferometry ◽  
High Accuracy ◽  
Angle Measurements ◽  
Beam Parameters

Abstract The paper introduces a new laser interferometry–based method for diagnosis of random media by means of high-accuracy angle measurements and describes the results of its development and testing. Theoretical calculations of the dependence of the range of the laser interferometer on laser beam parameters, device geometry, and atmospheric turbulence characteristics are reported. It is demonstrated that at moderate turbulence intensities corresponding to those observed most frequently in turbulent atmosphere at moderate latitudes and with low interference contrast values, the performance range of the laser interferometer–based device exceeds 5 km.

Research on Measurement of Ball Screw Helical Line Error Based on Electronic Generative Metrology

2014 ◽  
Vol 602-605 ◽  
pp. 2257-2262
Author(s):  
Hai Tao Li ◽  
Jun Jie Guo ◽  
Hong Feng Du ◽  
Xing Wang
Keyword(s):  
Measurement Accuracy ◽  
Experimental Studies ◽  
New Method ◽  
Ball Screw ◽  
Measuring Instruments ◽  
Helical Line ◽  
Measuring Head ◽  
High Precision Measurement ◽  
Measuring Device ◽  
Close Loop Control

Aiming at the disadvantages of current error measuring instruments of ball screw helix, a new screw helical line error measuring device is developed, moreover, a new method called electronic generative metrology (EGM) is introduced. The problem of measuring head deformation has been settled down because of installation of two driving motors on the instrument, so it is easy to achieve dynamic high precision measurement. Taking the long grating and circular grating as length and angle measurement datum respectively, the torque motor and linear motor are able to form position close-loop control. The measuring head frame is installed on air flotation slider which has characters of high kinematic accuracy and stability, so it guarantees high measurement accuracy. Then, the measurement accuracy analysis of the device is given. And the last, the EGM is developed by using this new research tool. Related experimental studies are conducted to verify the feasibility of the new method.

scholarly journals Application of new turbulent method for determining vertical refraction

2021 ◽  
Vol 11 (1) ◽  
pp. 102-110
Author(s):  
S. A. Younes
Keyword(s):  
Turbulent Atmosphere ◽  
Measurement Accuracy ◽  
New Method ◽  
Temperature Stratification ◽  
Total Station ◽  
Automatic Guidance ◽  
The Creation ◽  
Conventional Methods

Abstract This paper is concerned with the study of new turbulent method technique for the determining of vertical refraction when total stations are used. Required measurement accuracy of vertical refraction by conventional methods is extremely difficult due to rapid random changes in the angle of refraction. Geodetic observations are recommended to performing only during periods of indifferent temperature stratification, while the refraction is close to zero and practically unvaried. However, this period is extremely short and its boundaries are not defined, so the inefficiency of all known methods for determining refraction must be attention. The complete liberation of geodetic observations from the influence of turbulent and fluctuation processes in the atmosphere is possible only by directly measuring the angle of refraction at the time of observation. The creation of electronic total stations with automatic guidance to the target allows to successfully solving the problem of determining refraction by a turbulent method. The aim of this work is to study the new method for determining refraction in a turbulent atmosphere. The measurements are performed with a Trimble total station. The obtained results confirm that the accuracy for determining refraction is ~2″, which almost corresponds to the instrumental accuracy of the device used.

Experimental Studies of Sedimentation Basin Dynamics

1977 ◽  
Vol 12 (1) ◽  
pp. 77-90
Author(s):  
J.F. Cordoba-Molina ◽  
P.L. Silveston ◽  
R. R. Hudgins
Keyword(s):  
Dynamic Response ◽  
Froude Number ◽  
Flow Model ◽  
Experimental Studies ◽  
Densimetric Froude Number ◽  
Number Range ◽  
The Real ◽  
Highly Correlated ◽  
Sedimentation Basins ◽  
Simple Flow

Abstract A simple Flow Model is proposed to describe the dynamic response of sedimentation basins. The response predicted by this model is linear as opposed to the real response of the basin which is nonlinear. However, the real response of the basin is highly correlated with its densimetric Froude number, and as a consequence our linear model effectively predicts the response of the basin in a restricted densimetric Froude Number range. Our experiments show that the response of the basin becomes more sluggish and erratic as the densimetric Froude number decreases.

scholarly journals Performance Analysis of Surface Reconstruction Algorithms in Vertical Scanning Interferometry Based on Coherence Envelope Detection

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 164
Author(s):  
Dongxu Wu ◽  
Fusheng Liang ◽  
Chengwei Kang ◽  
Fengzhou Fang
Keyword(s):  
Surface Reconstruction ◽  
Measurement Accuracy ◽  
Experimental Studies ◽  
Reconstruction Algorithm ◽  
Low Noise ◽  
Surface Measurement ◽  
Reconstruction Algorithms ◽  
Centroid Method ◽  
Envelope Detection ◽  
Vertical Scanning Interferometry

Optical interferometry plays an important role in the topographical surface measurement and characterization in precision/ultra-precision manufacturing. An appropriate surface reconstruction algorithm is essential in obtaining accurate topography information from the digitized interferograms. However, the performance of a surface reconstruction algorithm in interferometric measurements is influenced by environmental disturbances and system noise. This paper presents a comparative analysis of three algorithms commonly used for coherence envelope detection in vertical scanning interferometry, including the centroid method, fast Fourier transform (FFT), and Hilbert transform (HT). Numerical analysis and experimental studies were carried out to evaluate the performance of different envelope detection algorithms in terms of measurement accuracy, speed, and noise resistance. Step height standards were measured using a developed interferometer and the step profiles were reconstructed by different algorithms. The results show that the centroid method has a higher measurement speed than the FFT and HT methods, but it can only provide acceptable measurement accuracy at a low noise level. The FFT and HT methods outperform the centroid method in terms of noise immunity and measurement accuracy. Even if the FFT and HT methods provide similar measurement accuracy, the HT method has a superior measurement speed compared to the FFT method.

scholarly journals Optical Inspection Systems for Axisymmetric Parts with Spatial 2D Resolution

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1218
Author(s):  
Aleksandr Kulchitskiy
Keyword(s):  
Control System ◽  
Optical System ◽  
Measurement Accuracy ◽  
Experimental Studies ◽  
Digital Camera ◽  
Digital Cameras ◽  
Bodies Of Revolution ◽  
Optical Inspection ◽  
Inspection Systems ◽  
Projection Error

The article proposes a solution to the problem of increasing the accuracy of determining the main shaping dimensions of axisymmetric parts through a control system that implements the optical method of spatial resolution. The influence of the projection error of a passive optical system for controlling the geometric parameters of bodies of revolution from the image of its sections, obtained by a digital camera with non-telecentric optics, on the measurement accuracy is shown. Analytical dependencies are derived that describe the features of the transmission of measuring information of a system with non-telecentric optics in order to estimate the projection error. On the basis of the obtained dependences, a method for compensating the projection error of the systems for controlling the geometry of the main shaping surfaces of bodies of revolution has been developed, which makes it possible to increase the accuracy of determining dimensions when using digital cameras with a resolution of 5 megapixels or more, equipped with short-focus lenses. The possibility of implementing the proposed technique is confirmed by the results of experimental studies.

scholarly journals High-Accuracy Calibration Based on Linearity Adjustment for Eddy Current Displacement Sensor

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2842 ◽  
Author(s):  
Wei Liu ◽  
Bing Liang ◽  
Zhenyuan Jia ◽  
Di Feng ◽  
Xintong Jiang ◽  
...  
Keyword(s):  
Eddy Current ◽  
Measurement Accuracy ◽  
Characteristic Curve ◽  
Calibration Method ◽  
High Accuracy ◽  
Output Characteristic ◽  
Displacement Sensor ◽  
Support Vector ◽  
Displacement Sensors ◽  
Calibration Accuracy

High precision position control is essential in the process of parts manufacturing and assembling, where eddy current displacement sensors (ECDSs) are widely used owing to the advantages of non-contact sensing, compact volume, and resistance to harsh conditions. To solve the nonlinear characteristics of the sensors, a high-accuracy calibration method based on linearity adjustment is proposed for ECDSs in this paper, which markedly improves the calibration accuracy and then the measurement accuracy. After matching the displacement value and the output voltage of the sensors, firstly, the sensitivity is adjusted according to the specified output range. Then, the weighted support vector adjustment models with the optimal weight of the zero-scale, mid-scale and full-scale are established respectively to cyclically adjust the linearity of the output characteristic curve. Finally, the final linearity adjustment model is obtained, and both the calibration accuracy and precision are verified by the established calibration system. Experimental results show that the linearity of the output characteristic curve of ECDS adjusted by the calibration method reaches over 99.9%, increasing by 1.9–5.0% more than the one of the original. In addition, the measurement accuracy improves from 11–25 μ m to 1–10 μ m in the range of 6mm, which provides a reliable guarantee for high accuracy displacement measurement.

The Revised Universal Slope Method to Predict the Low-Cycle Fatigue Lives of Elbow and Tee Pipes

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hiun Nagamori ◽  
Koji Takahashi
Keyword(s):  
Experimental Data ◽  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Experimental Studies ◽  
High Accuracy ◽  
Universal Method ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Slope Method ◽  
Stress States

The stress states of elbow and tee pipes are complex and different from those of straight pipes. The low-cycle fatigue lives of elbows and tees cannot be predicted by Manson's universal slope method; however, a revised universal method proposed by Takahashi et al. was able to predict with high accuracy the low-cycle fatigue lives of elbows under combined cyclic bending and internal pressure. The objective of this study was to confirm the validity of the revised universal slope method for the prediction of low-cycle fatigue behaviors of elbows and tees of various shapes and dimensions under conditions of in-plane bending and internal pressure. Finite element analysis (FEA) was carried out to simulate the low-cycle fatigue behaviors observed in previous experimental studies of elbows and tees. The low-cycle fatigue behaviors, such as the area of crack initiation, the direction of crack growth, and the fatigue lives, obtained by the analysis were compared with previously obtained experimental data. Based on this comparison, the revised universal slope method was found to accurately predict the low-cycle fatigue behaviors of elbows and tees under internal pressure conditions regardless of differences in shape and dimensions.

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