Technical Papers & Journals

Laser/Optical Scanning: Technology Overview From a User’s Perspective

Volume 14, Issue 2

Kyle Ferguson, John Bernardin, Dusan Spernjak

Laser and optical scanning technology has shown great progress over the past decade, with uses in applications such as manufacturing quality control, reverse engineering, recording historic sites, and more. Scanning equipment is readily available for capturing three dimensional (3D) geometry on a large scale (e.g., buildings, vehicles, and outdoor settings) as well as a small scale (e.g., machined or 3D-printed components with a length scale on the order of inches or feet). In this article, we compile the information on commercially available small-scale scanning systems. This snapshot of the current stateof-the-art can serve as a valuable reference for potential new users, as well as a valuation of the technology for possible new applications. We present case studies and applications of laser scanning which are unique to Los Alamos National Laboratory (LANL) (Los Alamos, NM) and conduct technology assessments of specific metrology applications.

Software Configuration Management and Automated Secure Data Storage for Metrology Processes

Volume 14, Issue 1

Robert Flynn, Schuyler Horky

The mission of this project was to compensate and locate with six degrees of freedom (6DOF) several hundred two- or three-axis machines, all with an evolving software process and changing inputs. In this work, several significant data-handling problems arose: How were all input data, scripts, and other software versions to be kept under revision control with weekly or daily changes as well as several metrology teams running multiple shifts? How could engineers process the avalanche of incoming data without being overwhelmed by it? What could be done to prevent data loss due to operator error? How might all data be reliably archived and reports protected from accidental change? This article describes an effort to grapple with these questions and a gradual evolution from primitive to more sophisticated solutions that raised the bar a little on our own best practices for repeated metrology operations.

Automated Navy Radar Array Survey With Laser Trackers

Volume 14, Issue 1

Wilvin Crawford, Roianthony Navarro, Steven Seiler, Scott Sandwith

The Combat System Alignment (CSA) survey for the AN/ SPY-1 phased array radar system is a critical and complex task that takes place over multiple nights either onboard one of the more than 100 ships or on site at the Ballistic Missile Defense (BMD) facilities and AEGIS shore sites worldwide. These ships and land-based sites are equipped with the AEGIS Combat System (ACS). The combat effectiveness of the ACS is dependent on the comprehensive and accurate completion of the surveying process. During the survey, several measurements must be completed, each with different tolerances and set-up challenges. The survey is an extensive process requiring great technical knowledge of surveying, the standard operating procedure (SOP) for surveying the AN/SPY-1 system, laser trackers, a computer, and, to operate the laser trackers, SpatialAnalyzer (SA) software from New River Kinematics (Williamsburg, VA). A measurement plan (MP) was written within SA to complete these periodic surveys standardizing the process and improving the measurement’s reliability.

Automated Laser Rail for ADM Calibration

David L. Linville, Yongwoo Park, Nay Lin, Yuanqun Lin

https://www.qualitydigest.com/inside/cmsc-article/automated-laser-rail-adm-calibration-052319.html...

Experimental Uncertainty Analysis for NDT on the CSX Wilbur Bridge

David H. Parker

https://www.qualitydigest.com/inside/cmsc-article/experimental-uncertainty-analysis-ndt-csx-wilbur-bridge-042319.html...

Calibration of a Six-Axis Serial Robotic Arm Mounted to a Moveable Base

Volume 13, Issue 2

Michael Allman, David Novotny, Josh Gordon

In this work, we present the calibration of a serial robotic positioner mounted to a rail system. This robot is one of two positioners that make up the Large Antenna Positioning System (LAPS) in the Communications Technology Laboratory (CTL) at the National Institute of Standards and Technology (NIST). The out-of-box positioning accuracy is approximately 1 mm. Using a custom Python package developed at NIST for automation, analysis, and control, we calibrated the robot’s kinematic model, improving the positioning accuracy to approximately 0.2 mm over a total working volume of approximately 10 m3. We discuss effects detrimental to accuracy such as mechanical backlash (hysteresis) and spatial drift and methods to mitigate them.

Effects of Filtering Factors of Scan Data on GD&T Analysis With Metrology Software

Volume 13, Issue 2

Onat Ekinci, John Chan, Mathieu Dube-Dallaire

The aim of this article is to analyze the measurement procedures for part inspection with metrology software using scanners in a non-controlled environment, and to demonstrate the effect of different ?ltering factors on geometric dimensioning and tolerancing (GD&T) analysis. The effects of GD&T ?t methods (i.e., least- squares vs. mating-envelope) are also investigated, because their behaviors vary greatly with noise levels. An experimental plan based on the design of experiments (DOE) methodology is applied to determine factors affecting the variability in GD&T analysis. Experimental test cases combining these factors are discussed, and best practices are accordingly proposed.

A New Model for Spherical Instrument Measurement Uncertainty

Volume 13, Issue 2

John W. Dorsey-Palmateer

Modeling uncertainty as point clouds is a good method for visualizing measurement uncertainties. Monte Carlo methods are often used to generate these point clouds by adding errors to a measurement and then iterating through tens or hundreds of measurement cycles. The result, when plotted, appears as a cloud of points surrounding the point of interest. In some cases, the uncertainties can be rather complicated when combining measurement uncertainties from multiple instruments. Monte Carlo uncertainty for spherical instruments (e.g., tracking interferometers or theodolites) using a spherical-to-cartesian coordinate transformation typically have point clouds that change from spheres at the equator to disks as the point clouds approach zenith and nadir. This does not comport with reality, because the lateral measurement uncertainty though an instrument is of the same order at all zenith angles. This article investigates this phenomenon and proposes an uncertainty model resulting in spherical uncertainty clouds at all angles.

Multiple Laser Tracker Synchronization for Vibration Analysis

Volume 13, Issue 2

Jana Barker, Charles Wilson, Horst Friedsam

Measuring the mechanical coupling and rigidity of a large apparatus presents unique challenges for 3D metrology. In this case, the motion of well-separated points attached to a rotor blade must be rapidly and repeatedly measured, and the resulting data synchronized. This article describes the methodology and results for the mechanical coupling test of the magnetic field mapping system (FMS) for the Muon-to-Electron Conversion Experiment (Mu2e) at Fermi National Accelerator Laboratory (Fermilab). Three laser trackers (two Radians and one T3, all from Automated Precision Inc. of Rockville, MD) simultaneously measured the position of three cylindrical corner-cube reflectors mounted on the FMS, both as the system was in motion and after coming to rest. The laser trackers took measurements at 83 Hz for the T3 and 100 Hz for the Radians, with fine spatial resolution, resulting in more than 20,000 points measured per instrument in the observation cycle. The laser tracker hardware and available software were unable to synchronize the three independent data streams directly during the measurement process. Therefore, a custom software program was developed to perform this synchronization of the data sequences during post-processing using features of the targets’ motion common to all three fiducial locations.

Experimental Evaluation of Leica T-Mac Angular Accuracy

Volume 13, Issue 2

Zheng Wang, Patrick Keogh

The Tracker Machine (T-Mac) control sensor from Leica (Hexagon Manufacturing Intelligence, North Kingstown, RI) is a unique, dynamic, large-volume six degree of freedom (6DOF) metrology system widely used for scanning, probing, and calibration, as well as real-time control of machine tools and robots. It is a hybrid metrology system utilizing both laser tracking and active photogrammetry, where the laser tracker system provides the 3DOF position and the photogrammetry system provides 3DOF orientation. Although there exist international standards for evaluating the accuracy of laser trackers, there appears to be a lack of literature on the assessment of angular accuracy of this type of instrument. This article presents an experimental method of evaluating the T-Mac angular accuracy throughout its measurement range using a precision rotary table. The article describes the setup of the experiment and measurement comparisons at different ranges and orientations of the T-Mac.