scholarly journals Study on LT Accuracy Improvement by Calibration Based on Network Measurements

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7479
Author(s):  
Jesús Velázquez ◽  
Javier Conte ◽  
Ana Cristina Majarena ◽  
Jorge Santolaria
Keyword(s):  
Incidence Angle ◽  
Coordinate Measuring Machine ◽  
Calibration Procedure ◽  
Working Environment ◽  
Kinematic Parameters ◽  
Nominal Data ◽  
Network Measurements ◽  
Specialized Equipment ◽  
Measuring Machine ◽  
Error Parameter

Laser trackers (LT) are widely used to calibrate other machines. Nevertheless, very little is known about calibrating an LT. There are some standards that allow us to evaluate the LT performance. However, they require specialized equipment. A calibration procedure to improve the LT accuracy in an easy and fast way is presented in this paper. This method is based on network measurements where a set of reflectors were measured from different LT positions in a working environment. The methodology proposed deal with the lack of nominal data of the reflector mesh. A measurement scenario was defined, based on error parameter dependence on distances and angles, thus, obtaining those positions more sensitive to errors. The influence of the incidence angle of the laser beam on the reflector was characterized, revealing that its contribution to the LT measurement error can be up to 13 µm. Error kinematic parameters were identified to provide the optimum value of an objective function, where the reflector mesh nominal data were unknown. The calibration procedure was validated with nominal data, by measuring a set of reflectors located on a coordinate measuring machine. The findings of this study suggested that the LT accuracy can be improved up to 25%. Moreover, the method can be carried out by the LT user without requiring specialized equipment.

scholarly journals Articulated Arm Coordinate Measuring Machine Calibration by Laser Tracker Multilateration

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jorge Santolaria ◽  
Ana C. Majarena ◽  
David Samper ◽  
Agustín Brau ◽  
Jesús Velázquez
Keyword(s):  
Coordinate Measuring Machine ◽  
Spatial Localization ◽  
Model Parameters ◽  
Nominal Data ◽  
Identification Procedure ◽  
Calibration Algorithm ◽  
Measuring Machine ◽  
Euclidean Distances ◽  
Machine Calibration ◽  
Nonlinear Optimization Algorithm

A new procedure for the calibration of an articulated arm coordinate measuring machine (AACMM) is presented in this paper. First, a self-calibration algorithm of four laser trackers (LTs) is developed. The spatial localization of a retroreflector target, placed in different positions within the workspace, is determined by means of a geometric multilateration system constructed from the four LTs. Next, a nonlinear optimization algorithm for the identification procedure of the AACMM is explained. An objective function based on Euclidean distances and standard deviations is developed. This function is obtained from the captured nominal data (given by the LTs used as a gauge instrument) and the data obtained by the AACMM and compares the measured and calculated coordinates of the target to obtain the identified model parameters that minimize this difference. Finally, results show that the procedure presented, using the measurements of the LTs as a gauge instrument, is very effective by improving the AACMM precision.

Calibrator for 2D Grid Plate Using Imaging Coordinate Measuring Machine with Laser Interferometers

2015 ◽  
Vol 9 (5) ◽  
pp. 541-545 ◽  
Author(s):  
Mariko Kajima ◽  
◽  
Tsukasa Watanabe ◽  
Makoto Abe ◽  
Toshiyuki Takatsuji
Keyword(s):  
Measurement Method ◽  
Laser Interferometer ◽  
Coordinate Measuring Machine ◽  
Calibration Procedure ◽  
Expanded Uncertainty ◽  
Geometrical Error ◽  
Grid Plate ◽  
Measuring Machine ◽  
Laser Interferometers

A calibrator for 2D grid plates have been developed. The calibrator was based on a commercial imaging coordinate measuring machine (imaging CMM). A laser interferometer for the calibration of the x-coordinate and two laser interferometers for the calibration of the y-coordinate were attached to the imaging CMM. By applying multistep measurement method for the calibration procedure, the geometrical error in the calibrator was reduced. The calibration of a precision 2D grid plate was demonstrated, and the expanded uncertainty was estimated to be 0.2 μm (k =2).

scholarly journals Calibration Method of Parallel Mechanism Type Machine Tools

2020 ◽  
Vol 14 (3) ◽  
pp. 429-437
Author(s):  
Keisuke Nagao ◽  
◽  
Nobuaki Fujiki ◽  
Yoshitaka Morimoto ◽  
Akio Hayashi
Keyword(s):  
Machine Tools ◽  
Parallel Mechanism ◽  
Least Squares Method ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Kinematic Parameter ◽  
Forward Kinematics ◽  
Kinematic Parameters ◽  
Type Machine ◽  
Measuring Machine

This paper proposes a calibration method for a parallel mechanism type machine tool (XMINI, Exechon Enterprises L.L.C.). In this method, the kinematic parameters are calculated using forward kinematics and the least squares method from the results obtained by a coordinate measuring machine. By using an articulated arm coordinate measuring machine (AACMM), we can measure a wide space, and the measuring machine position do not have to be determined strictly. This paper provides a solution for the forward kinematics problem to identify the kinematic parameters. The results from the kinematic parameter calculation are evaluated using the experimental results from an actual machine.

A Kinematic Model for Parallel-Joint Coordinate Measuring Machine

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Jie Li ◽  
Lian-Dong Yu ◽  
Jing-Qi Sun ◽  
Hao-Jie Xia
Keyword(s):  
Mathematical Modeling ◽  
Data Processing ◽  
Newton Method ◽  
Measurement Accuracy ◽  
Kinematic Model ◽  
Coordinate Measuring Machine ◽  
Experimental Results ◽  
Kinematic Modeling ◽  
Kinematic Parameters ◽  
Measuring Machine

The typical nonorthogonal coordinate measuring machine is the portable coordinate measuring machine (PCMM), which is widely applied in manufacturing. In order to improve the measurement accuracy of PCMM, structural designing, data processing, mathematical modeling, and identification of parameters of PCMM, which are essential for the measurement accuracy, should be taken into account during the machine development. In this paper, a kind of PCMM used for detecting the crucial dimension of automobile chassis has been studied and calibrated. The Denavit–Hartenberg (D–H) kinematic modeling method has often been used for modeling traditional robot, but the D–H error representation is ill-conditioned when it is applied to represent parallel joints. A modified four-parameter model combined with D–H model is put forward for this PCMM. Based on the kinematic model, Gauss–Newton method is applied for calibrating the kinematic parameters. The experimental results indicate the improvement of measuring accuracy and the effectiveness of the PCMM based on the proposed method.

Calibration of Articulated Arm Coordinate Measuring Machine Considering Measuring Posture

2011 ◽  
Vol 5 (2) ◽  
pp. 109-114 ◽  
Author(s):  
Hiroyuki Hamana ◽  
◽  
Mitsushi Tominaga ◽  
Miyu Ozaki ◽  
Ryoshu Furutani
Keyword(s):  
Measurement Error ◽  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Coordinate Measuring Machines ◽  
Kinematic Parameters ◽  
Measuring Volume ◽  
Measuring Machine ◽  
Three Dimensional Coordinate

Three-dimensional Coordinate Measuring Machines (CMMs) are widely used to measure wide-ranging accuracy. Parameters describing CMM use mechanisms must be calibrated by measuring artifacts for the target CMM. Most CMM calibration studies have covered orthogonal rather than non-orthogonal CMMs. We focused on calibration for a nonorthogonal articulated-Arm CMM (ACMM), which has more measurement freedom than an orthogonal CMM, although ACMM measurement error exceeds that of orthogonal CMMs. The kinematic parameters of ACMM are calibrated using spherical center coordinates as the artifact. Part of the measuring volume is calibrated, but the ACMM is not sufficiently calibrated. To calibrate arm deformation in different measurement posture as well as kinematic parameters, we produced a new artifact for which we propose calibration confirmed in experiments.

scholarly journals Evaluation of dimensional accuracy of dental bridges manufactured with conventional casting technique and CAD/CAM system with Ceramill Sintron blocks using CMM

2018 ◽  
Vol 12 (4) ◽  
pp. 264-271 ◽  
Author(s):  
Alireza Izadi ◽  
Fariborz Vafaee ◽  
Arash Shishehian ◽  
Ghodratollah Roshanaei ◽  
Behzad Fathi Afkari
Keyword(s):  
Reference Model ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Three Dimensions ◽  
Casting Technique ◽  
Dimensional Changes ◽  
Conventional Casting ◽  
Cad Cam ◽  
Milling Method ◽  
Measuring Machine

Background. Recently, non-presintered chromium-cobalt (Cr-Co) blocks with the commercial name of Ceramill Sintron were introduced to the market. However, comprehensive studies on the dimensional accuracy and fit of multi-unit frameworks made of these blocks using the coordinate measuring machine (CMM) are lacking. This study aimed to assess and compare the dimensional changes and fit of conventional casting and milled frameworks using Ceramill Sintron. Methods. A metal model was designed and scanned and 5-unit frameworks were fabricated using two techniques: (I) the conventional casting method (n=20): the wax model was designed, milled in the CAD/CAM machine, flasked and invested; (II) the milling method using Ceramill Sintron blocks (n=20): the wax patterns of group 1 were used; Ceramill Sintron blocks were milled and sintered. Measurements were made on the original reference model and the fabricated frameworks using the CMM in all the three spatial dimensions, and dimensional changes were recorded in a checklist. Data were analyzed with descriptive statistics, and the two groups were compared using one-way ANOVA and Tukey test (α=0.05). Results. The fabricated frameworks in both groups showed significant dimensional changes in all the three dimensions. Comparison of dimensional changes between the two groups revealed no significant differences (P>0.05) except for transverse changes (arch) that were significantly greater in Ceramill Sintron frameworks (P<0.05). Conclusion. The two manufacturing processes were the same regarding dimensional changes and the magnitude of marginal gaps and both processes resulted in significant dimensional changes in frameworks. Ceramill Sintron frameworks showed significantly greater transverse changes than the conventional frameworks.

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