scholarly journals A Study on the Uncertainty of a Laser Triangulator Considering System Covariances

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1630
Author(s):  
Pablo Puerto ◽  
Beñat Estala ◽  
Alberto Mendikute
Keyword(s):  
Error Propagation ◽  
Measurement Accuracy ◽  
Maximum Error ◽  
Experimental Methodology ◽  
Joint Measurement ◽  
Error Sources ◽  
Processing Times ◽  
Main Error ◽  
Laser Plane ◽  
System Variables

A laser triangulation system, which is composed of a camera and a laser, calculates distances between objects intersected by the laser plane. Even though there are commercial triangulation systems, developing a new system allows the design to be adapted to the needs, in addition to allowing dimensions or processing times to be optimized; however the disadvantage is that the real accuracy is not known. The aim of the research is to identify and discuss the relevance of the most significant error sources in laser triangulator systems, predicting their error contribution to the final joint measurement accuracy. Two main phases are considered in this study, namely the calibration and measurement processes. The main error sources are identified and characterized throughout both phases, and a synthetic error propagation methodology is proposed to study the measurement accuracy. As a novelty in uncertainty analysis, the present approach encompasses the covariances of correlated system variables, characterizing both phases for a laser triangulator. An experimental methodology is adopted to evaluate the measurement accuracy in a laser triangulator, comparing it with the values obtained with the synthetic error propagation methodology. The relevance of each error source is discussed, as well as the accuracy of the error propagation. A linearity value of 40 µm and maximum error of 0.6 mm are observed for a 100 mm measuring range, with the camera calibration phase being the main error contributor.

Improvement and Error Analysis of Spring Tube Stiffness Measurement

2014 ◽  
Vol 621 ◽  
pp. 443-449
Author(s):  
Wen Xuan Liu ◽  
Hui Feng Wang ◽  
Guang Lin Wang ◽  
Dong Xiang Shao
Keyword(s):  
Measurement Accuracy ◽  
Error Source ◽  
Element Analysis ◽  
Error Sources ◽  
Stiffness Measurement ◽  
Main Error ◽  
Measure Methods ◽  
Measured Deformation ◽  
Main Components ◽  
The Relationship

This article analyzes the deviation of existing stiffness measurement method and comes to the main components of the measurement error. Focus on the influence of the bending deformation all of aspects and contact deformation between the various links to the measurement accuracy. Establish the relationship between the actual deformation and the measured deformation to the spring tube through homogeneous coordinate transformation and finite element analysis, in order to identify the error sources impact on the measurement greatest, and improve the measure methods to against the main error source, eliminate the influence of the main error source to the stiffness measurement, then achieve the purpose of improving the measure accuracy.

Study on Dynamic Accuracy of CNC in Aviation Part

2011 ◽  
Vol 314-316 ◽  
pp. 1717-1720
Author(s):  
Li Du ◽  
Wei Wang ◽  
Zhi Yong Song ◽  
Jie Xiong Ding
Keyword(s):  
High Speed ◽  
Influence Factors ◽  
Maximum Error ◽  
Error Sources ◽  
Dynamic Accuracy ◽  
Cutting Test ◽  
Manufacture Process ◽  
Shape Precision ◽  
Dynamic Errors ◽  
And Control

Thin-walled parts are widely used in aerospace engineering. For their complexity under loading and the higher shape precision, it’s difficult for their manufacturing on high speed machine. In order to understand manufacture process, characteristic of aviation part in high speed machining is investigated. Error sources on parts are classified and the maximum error, dynamic errors are studied on its main influence factors, such as cutting force and vibration. Finally, useful method on cutting test part is proposed, which can observe and control dynamic accuracy of aviation part and ensure effective manufacture.

Error sources and models of the laser tracker without a beam steering mirror

2021 ◽  
Author(s):  
Radoslav Choleva ◽  
Alojz Kopáčik
Keyword(s):  
Measurement Accuracy ◽  
Beam Steering ◽  
Systematic Errors ◽  
Error Modeling ◽  
Laser Tracker ◽  
High Demand ◽  
Error Sources ◽  
Error Models ◽  
Measurement Results

AbstractThe laser tracker is a widely used instrument in many industrial and metrological applications with high demand measurement accuracy. Imperfections in construction and misalignment of individual parts deliver systematic errors in the measurement results. All error sources need to be identified and reduced to the minimum to achieve the best possible accuracy. The paper summarizes error sources of the laser tracker without beam steering mirror with emphasis on error modeling. Descriptions of error models are provided for the static and kinematic type of measurement.

Investigation of the influence of the main error sources on the capacitive displacement measurements with cylindrical artefacts

2013 ◽  
Vol 37 (3) ◽  
pp. 721-737 ◽  
Author(s):  
Hichem Nouira ◽  
Alain Vissiere ◽  
Mohamed Damak ◽  
Jean-Marie David
Keyword(s):  
Error Sources ◽  
Main Error ◽  
Displacement Measurements

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.

A Novel Approach to Kinematic Reliability Analysis for Planar Parallel Manipulators

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Qiangqiang Zhao ◽  
Junkang Guo ◽  
Dingtang Zhao ◽  
Dewen Yu ◽  
Jun Hong
Keyword(s):  
Reliability Analysis ◽  
Error Propagation ◽  
Simulation Method ◽  
Parallel Manipulators ◽  
Plane Motion ◽  
Error Sources ◽  
Novel Approach ◽  
Safe Region ◽  
Motion Groups ◽  
Planar Parallel Manipulators

Abstract Kinematic reliability is an essential index that assesses the performance of the mechanism associating with uncertainties. This study proposes a novel approach to kinematic reliability analysis for planar parallel manipulators based on error propagation on plane motion groups and clipped Gaussian in terms of joint clearance, input uncertainty, and manufacturing imperfection. First, the linear relationship between the local pose distortion coming from the passive joint and that caused by other error sources, which are all represented by the exponential coordinate, are established by means of the Baker–Campbell–Hausdorff formula. Then, the second-order nonparametric formulas of error propagation on independent and dependent plane motion groups are derived in closed form for analytically determining the mean and covariance of the pose error distribution of the end-effector. On this basis, the kinematic reliability, i.e., the probability of the pose error within the specified safe region, is evaluated by a fast algorithm. Compared to the previous methods, the proposed approach has a significantly high precision for both cases with small and large errors under small and large safe bounds, which is also very efficient. Additionally, it is available for arbitrarily distributed errors and can analyze the kinematic reliability only regarding either position or orientation as well. Finally, the effectiveness and advantages of the proposed approach are verified by comparing with the Monte Carlo simulation method.

A study on the mechanism reduction and evaluation of biodiesel with the change of mechanism reduction factors

2020 ◽  
Vol 234 (14) ◽  
pp. 3398-3413
Author(s):  
Jun Woo Jung ◽  
Young Chan Lim ◽  
Hyun Kyu Suh
Keyword(s):  
Error Propagation ◽  
Three Dimensional ◽  
Reduction Process ◽  
Threshold Value ◽  
Maximum Error ◽  
Target Species ◽  
Ambient Conditions ◽  
Mechanism Reduction ◽  
Relative Tolerance ◽  
Relation Graph

This study aims to confirm the effect of changing the various factors with the directed relation graph error propagation–based methods and to adopt a new approach of the mechanism evaluation in the reduction of biodiesel mechanism. The factors considered in this study were a threshold value, target species, ambient conditions, and the evaluation formula consists of the reduction rates and the maximum error rate of ignition delay to objectively compare the skeletal mechanisms generated under different conditions. For a threshold value, the automatic mechanism reduction process was used to select the appropriate threshold value by applying the relative tolerance and absolute tolerance; so relative tolerance and absolute tolerance represent the factor of the threshold value. Also, the seven steps of mechanism reduction process consist of directed relation graph error propagation, directed relation graph error propagation with sensitivity analysis, peak concentration analysis, full species sensitivity analysis, and A-factor modification. As a result of the mechanism reduction, different relative tolerance and absolute tolerance values should be applied to each step to select the appropriate threshold value. For target species, considering polycyclic aromatic hydrocarbon species as target species shows higher efficiency of mechanism reduction. Also, considering the negative temperature coefficient region as ambient conditions helps the mechanism be reduced efficiently than a wide range of ambient conditions. Finally, the reduced mechanism which had 247 species and 1129 reactions was generated, and the maximum error rate of ignition delay was about 30%. For the applicability of three-dimensional computational fluid dynamics and verification of the reduced mechanism, the compression ignition engine simulation was performed. As a result of three-dimensional computational fluid dynamics, the predicted cylinder pressure, rate of heat release, indicated mean effective pressure, and power were similar to the experimental results. However, the results of carbon monoxide and nitrogen oxide emissions did not match the experimental results.

scholarly journals Error Analysis and Compensation of a Laser Measurement System for Simultaneously Measuring Five-Degree-of-Freedom Error Motions of Linear Stages

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3833 ◽  
Author(s):  
Yindi Cai ◽  
Qi Sang ◽  
Zhi-Feng Lou ◽  
Kuang-Chao Fan
Keyword(s):  
Measurement System ◽  
Measurement Accuracy ◽  
Measurement Model ◽  
Degree Of Freedom ◽  
Linear Stage ◽  
Laser Measurement ◽  
Beam Spot ◽  
Error Sources ◽  
Laser Measurement System ◽  
Dual Beam

A robust laser measurement system (LMS), consisting of a sensor head and a detecting part, for simultaneously measuring five-degree-of-freedom (five-DOF) error motions of linear stages, is proposed and characterized. For the purpose of long-travel measurement, all possible error sources that would affect the measurement accuracy are considered. This LMS not only integrates the merits of error compensations for the laser beam drift, beam spot variation, detector sensitivity variation, and non-parallelism of dual-beam that have been resolved by the author’s group before, but also eliminates the crosstalk errors among five-DOF error motions in this study. The feasibility and effectiveness of the designed LMS and modified measurement model are experimentally verified using a laboratory-built prototype. The experimental results show that the designed LSM has the capability of simultaneously measuring the five-DOF error motions of a linear stage up to one-meter travel with a linear error accuracy in sub-micrometer and an angular error accuracy in sub-arcsecond after compensation.

scholarly journals Geometric, Environmental and Hardware Error Sources of a Ground-Based Interferometric Real-Aperture FMCW Radar System

2018 ◽  
Vol 10 (12) ◽  
pp. 2070 ◽  
Author(s):  
Rune Gundersen ◽  
Richard Norland ◽  
Cecilie Rolstad Denby
Keyword(s):  
Electromagnetic Waves ◽  
Measurement Accuracy ◽  
Careful Analysis ◽  
Radar System ◽  
Corner Reflector ◽  
Error Sources ◽  
Fmcw Radar ◽  
Radar Systems ◽  
Range Cell ◽  
Induced Changes

Ground-based interferometric radar systems have numerous environmental monitoring applications in geoscience. Development of a relatively simple ground-based interferometric real-aperture FMCW radar (GB-InRAR) system that can be readily deployed in field without an established set of corner reflectors will meet the present and future need for real-time monitoring of the expected increased number of geohazard events due to climate changes. Several effects affect electromagnetic waves and limit the measurement accuracy, and a careful analysis of the setup of the deployed radar system in field is essential to achieve adequate results. In this paper, we present radar measurement of a moving square trihedral corner reflector from experiments conducted in both the field and laboratory, and assess the error sources with focus on the geometry, hardware and environmental effects on interferometric and differential interferometric measurements. A theoretical model is implemented to assess deviations between theory and measurements. The main observed effects are variations in radio refractivity, multipath interference and inter-reflector interference. Measurement error due to radar hardware and the environment are analyzed, as well as how the geometry of the measurement setup affects the nominal range-cell extent. It is found that for this experiment the deviation between interferometry and differential interferometry is mainly due to variations in the radio refractivity, and temperature-induced changes in the electrical length of the microwave cables. The results show that with careful design and analysis of radar parameters and radar system geometry the measurement accuracy of a GB-InRAR system without the use of deployed corner reflectors is comparable to the accuracy of differential interferometric measurements. A GB-InRAR system can therefore be used during sudden geo-hazard events without established corner reflector infrastructure, and the results are also valid for other high-precision interferometric radar systems.

Error sources and error propagation in the Levinson-Durbin algorithm

1993 ◽  
Vol 41 (4) ◽  
pp. 1635-1651 ◽  
Author(s):  
C.N. Papaodysseus ◽  
E.B. Koukoutsis ◽  
C.N. Triantafyllou
Keyword(s):  
Error Propagation ◽  
Error Sources
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