scholarly journals Field spectrometer measurement errors in presence of partially polarized light; evaluation of ground truth measurement accuracy

2016 ◽  
Vol 24 (24) ◽  
pp. 27199
Author(s):  
Martin P. Lévesque ◽  
Maria Dissanska
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Polarized Light ◽  
Ground Truth

A Research on Improving the Precision of Rotating-Wave Plate Polarization Measurement

2015 ◽  
Vol 742 ◽  
pp. 105-110
Author(s):  
Meng Han Hou ◽  
Wu Mei Lin ◽  
Zhen Jie Fan
Keyword(s):  
Fourier Analysis ◽  
Measurement System ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Polarized Light ◽  
Polarization Measurement ◽  
Angle Error ◽  
Wave Plate ◽  
Stokes Vectors ◽  
Rotating Wave

The device errors of a rotating-wave-plate-based polarization measurement system can be mainly categorized as the angle error of the polarization prism, the fast axis angle error of wave-plate and the retardation error. By applying Fourier analysis to solve Stokes vectors, we obtain the formulas to calculate the three errors mentioned above, using linear 0° and 45° polarized light to illuminate the system for the error solving. We analyze the measurement errors of the degree of polarization, the polarization purity and the intensity of polarization state, under certain simulation conditions. The results show that after the calibration, the measurement accuracy is improved. Finally, we analyze the effects of the angle error of the linear polarized light used for calibration to the measurement of the three parameters.

A weighted fusion method with multi-system for improving measurement accuracy of structured light 3D profilometry

2021 ◽  
Author(s):  
Chao Xing ◽  
Junhui Huang ◽  
Zhao Wang ◽  
Jianmin Gao
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Structured Light ◽  
Profile Measurement ◽  
Complex Surfaces ◽  
3D Profilometry ◽  
Weighted Fusion ◽  
Multiple Measurements ◽  
Geometric Relationship ◽  
3D Profile

Abstract It is a challenge to improve the accuracy of 3D profile measurement based on binary coded structured light for complex surfaces. A new method of weighted fusion with multi-system is presented to reduce the measurement errors due to the stripe grayscale asymmetry, which is based on the analysis of stripe center deviation related to surface normal and the directions of incident and reflected rays. First, the stripe center deviation model is established according to the geometric relationship between the stripe center deviation, the incident and reflected angles at any measured point. The influence of each variable on stripe center deviation is analyzed, and three subsystems are formed by a binocular structured light framework to achieve multiple measurements based on the influence regularity. Then in order to improve the measurement accuracy, different weights are assigned to the measured point in different subsystems according to the stripe center deviation model and its relationship with measurement error, and the weighted data from different subsystems are fused. Experiments are carried out to validate the presented method, and the experimental results demonstrate that it effectively improves the measurement accuracy of complex surfaces and measurement accuracy is improved by about 27% compared with the conventional method.

scholarly journals Vehicular Localization Enhancement via Consensus

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6506
Author(s):  
Hong Ki Kim ◽  
Minji Kim ◽  
Sang Hyun Lee
Keyword(s):  
Measurement Errors ◽  
Environmental Changes ◽  
Ground Truth ◽  
Localization Error ◽  
Local Data ◽  
Implementation Techniques ◽  
Estimate Error ◽  
Localization Performance ◽  
Update Rules ◽  
Location Estimate

This paper presents a strategy to cooperatively enhance the vehicular localization in vehicle-to-everything (V2X) networks by exchanges and updates of local data in a consensus-based manner. Where each vehicle in the network can obtain its location estimate despite its possible inaccuracy, the proposed strategy takes advantage of the abundance of the local estimates to improve the overall accuracy. During the execution of the strategy, vehicles exchange each other’s inter-vehicular relationship pertaining to measured distances and angles in order to update their own estimates. The iteration of the update rules leads to averaging out the measurement errors within the network, resulting in all vehicles’ localization error to retain similar magnitudes and orientations with respect to the ground truth locations. Furthermore, the estimate error of the anchor—the vehicle with the most reliable localization performance—is temporarily aggravated through the iteration. Such circumstances are exploited to simultaneously counteract the estimate errors and effectively improve the localization performance. Simulated experiments are conducted in order to observe the nature and its effects of the operations. The outcomes of the experiments and analysis of the protocol suggest that the presented technique successfully enhances the localization performances, while making additional insights regarding performance according to environmental changes and different implementation techniques.

On the use of optical fibres in a pulsed time-of-flight laser rangefinder

Robotica ◽  
1995 ◽  
Vol 13 (1) ◽  
pp. 45-53
Author(s):  
Seppo Nissilä ◽  
Juha Kostamovaara
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Time Of Flight ◽  
Optical Fibres ◽  
Optical Pulses ◽  
Bending Vibration ◽  
Error Sources ◽  
Measuring Devices ◽  
Hot Surface ◽  
Industrial Measurement

SummaryThe pulsed time-of-flight laser rangefinding technique has been used in many industrial measurement applications, including 3D-coordinate measuring devices, hot surface profilers and mobile robot sensors. Optical fibres, typically 1–10 m in length and 100–400 μm in diameter can be used to guide optical pulses to the separate sensing head of the measurement device. The use of a large multimode fibre may cause problems, however, when aiming at millimetre accuracy, as the construction and adjustment of the optics of the sensor head may affect the transit time linearity and measurement accuracy via multimode dispersion. Environmental effects, such as bending, vibration due to the moving sensing head and temperature, also cause measurement errors. The error sources are studied and characterized in this paper.

scholarly journals Calibration and Accuracy Determination of a Microwave Type Sensor for Measuring Grain Flow

2014 ◽  
Vol 931-932 ◽  
pp. 1592-1596
Author(s):  
Renny Eka Putri ◽  
Azmi Yahya ◽  
Nor Maria Adam ◽  
Samsuzana Abd Aziz ◽  
Tajudeen Abiodun Ishola
Keyword(s):  
Real Time ◽  
Pitch Angle ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Evaluation Study ◽  
Flow Sensor ◽  
Roll Angle ◽  
Flow Measurements ◽  
Solid Flow ◽  
Grain Flow

Impact type grain flow sensor for crop yield monitoring is known to have problem of some thrown grain by the elevator conveyor in a combine not hitting the sensing impact plate. New technology of microwave solid flow sensor was used to solve the problem of impact-type sensor. A calibration stand with its instrumentation systems to stimulate the actual operation of the clean grain auger in a rice combine had been designed and constructed in this study for the purpose of conducting the calibration and evaluation study of the sensor. Two different solid flow sensor orientations and three different solid flow sensor extrusions were investigated in order to find the best positioning of the sensor on the chute for the measurement. Results from the conducted tests indicates that the best sensor positioning is on totally flat ground at 180o orientation and 8 cm extrusion of the chute cross section (R2=0.9400). Then, the solid flow sensor was tested at seven chute pitch angle positions (i.e-4.5o, -3.0o, -1.5o, 0o, +1.5o, + 3.0o, and +4.5 o), seven chute roll angle positions (i.e-4.5o,-3.0o, -1.5 o, 0o, +1.5o, +3.0 o, and +4.5o). Finally, accuracy tests undertaken to compare the real time measurements against the average flow measurements. ANOVA test shows that both pitch angle and roll angle positions have significant effects on the measurement accuracy of the sensor. The measurement errors increased with increasing roll angles and increasing pitch angle. Conclusively, this conducted laboratory study was able to quantify the measurement accuracy of the SWR Solid Flow sensor for real-time measurement of grain flow under a simulated laboratory rice combine test set-up.

Safety Factor for Flaw Evaluation of a Pipe Having a Circumferential Surface Flaw

2015 ◽  
Author(s):  
Hideo Machida ◽  
Manabu Arakawa
Keyword(s):  
Failure Probability ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Material Strength ◽  
Safety Factors ◽  
First Order ◽  
The Monte Carlo Method ◽  
Surface Flaws ◽  
First Order Second Moment ◽  
Second Moment Method

This paper describes the safety factors used for fracture assessments of pipes having circumferential surface flaws. The “Fitness-For-Services Codes (the FFS Codes)” of the Japan Society of Mechanical Engineers (JSME) restrict the depths of flaws according to their angles to prevent pipes with flaws from being fracture. Past restrictions were determined based on deterministic evaluations. In fracture assessments of pipes having flaws, however, the effects of measurement errors in flaw dimensions and of variations on material strength must be taken into account. Thus, we evaluated the effects of such variations on fracture assessments of pipes having flaws, and examined safety factors for giving failure probability (or reliability) equal, irrespective of the cracking angles. We found out that failure probability is heavily dependent on the measurement accuracy of flaw depths and material strength (flow stress). In view of this finding, we examined and proposed a simple approach which meets the target reliability without conducting complex evaluations by the Monte Carlo method and reliability evaluation methods (e.g., first-order second-moment method (FOSM)).

Research on Linear Array TDI-CCD System with Noise Suppression

2013 ◽  
Vol 274 ◽  
pp. 266-269
Author(s):  
Ke Ming Li ◽  
Chao Zhang
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Noise Suppression ◽  
Linear Array ◽  
Signal To Noise Ratio ◽  
Software Implementation ◽  
Image Measurement ◽  
Correlated Double Sampling ◽  
The Mathematical Model ◽  
Processing Circuit

Noises in the imaging process will result in image measurement errors, so whether these noises can be effectively suppressed is the key to improve the measurement accuracy. This paper analyzes the noise components of TDI-CCD system from three perspectives, builds the mathematical model of typical noises, designs correlated double sampling noise processing circuit for TDI-CCD system, realizes the software implementation of hardware design and achieves the purpose to improve the signal-to-noise ratio and image quality

Research on the Method of the Calibration of 3D Linear Scanning Probe System

2011 ◽  
Vol 121-126 ◽  
pp. 1073-1079
Author(s):  
Peng Wan ◽  
Jun Jie Guo ◽  
Pei Lin Wu ◽  
Zhi Gen Fei
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Coefficient Matrix ◽  
3D Scanning ◽  
Least Square ◽  
Scanning Probe ◽  
Measuring Instrument ◽  
Probe System ◽  
Calibration Matrix ◽  
Linear Scanning

3D scanning probe is a kind of measuring instrument that is an indispensable part of Gear Measuring Center. It’s used for obtaining micro-displacement in three directions through the deformation of the three mutually vertical parallel springs. The accuracy of the probe system has critical influence on Gear Measuring Center. Because of the limitation of the structure of parallel spring, the installation errors of the probe and the influence of environmental factors, the parallel springs in three directions are not always strictly vertical, the interference and coupling among X,Y,Z directions exist. This problem is very difficult to be solved by adjusting the mechanical structure of 3D scanning probe system. However, the accuracy of probe system can be improved by adopting software-compensation through calibration. In the paper, the calibration matrix of the probe system is generated by fitting the points sampled on the standard ball with the method of the least square. The points are sampled through controlling the probe to touch standard ball in several given directions. The experimental results show that the measurement errors caused by the coupling among the three perpendicular directions can be effectively decreased by the coefficient matrix mentioned above. The method of calibration is practical and effective for improving the measurement accuracy of 3D scanning probe.

scholarly journals Experimental study on improving the accuracy of marine gravimetry by combining moving-base gravimeters with GNSS antenna array

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Zhimin Shi ◽  
Junjian Lang ◽  
Xinghui Liang ◽  
Zhibo Zhou ◽  
Aizhi Guo ◽  
...  
Keyword(s):  
Antenna Array ◽  
Real Time ◽  
Frequency Band ◽  
Antenna Arrays ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Tectonic Activity ◽  
Gravity Measurement ◽  
Vertical Position ◽  
Point Positioning

AbstractThe gravity field is one of the Earth’s basic physical fields. The geoid can be calculated and the tectonic activity underground can be inversed by gravity anomaly. With the development of various ship-borne gravimeters and navigation technology, including the Global Navigation Satellite System (GNSS) and Strapdown Inertial Navigation System (SINS), the precision of marine gravimetry has been significantly improved (achieve or better than 1mGal). Errors arising from calculations of the correction term have become the main source of gravity measurement errors. At present, the traditional approach is to deploy a GNSS antenna, connect the GNSS antenna to the gravimeter, record the real-time position through data acquisition software, and then use this position to calculate the gravity correction item afterward. Two errors are inevitable. (1) The GNSS antenna position error is large. The pseudorange point positioning method is generally used to obtain real-time GNSS antenna positions, and the positioning accuracy is poor compared with that of precise point positioning. (2) The position coordinates of the gravimeter contain systematic errors related to the ship’s attitude. In this paper, a joint experiment including GNSS antenna arrays and ship-borne gravimeters was designed to evaluate the measurement accuracy via repeat lines on the same ship. The experimental results show the following: (1) attitude accuracies of 0.0299° for the yaw angle, 0.0361° for the pitch angle, and 0.1671° for the roll angle can be obtained at baseline lengths of 25 and 4 m. (2) The GNSS antenna array has an obvious role in determining the point acceleration in the low-frequency band (0–0.01 Hz) and the point position and velocity in the high-frequency band (0.01–1 Hz). (3) The vertical position eccentricity causes an absolute error of 1 mGal and a relative error of $${10}^{-1}$$ 10 - 1 mGal in gravity measurements and can be corrected by the GNSS antenna array method. (4) Using a GNSS antenna array can obviously improve the measurement accuracy of an instrument with a precision equaling or exceeding 1 mGal, but cannot obviously improve that to an instrument with poor precision (2 mGal or below).

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