Technical Papers & Journals

Laser Tracking Measurement System Based on Dual-Femtosecond Optical Frequency Comb

Volume 14, Issue 1

Dengfeng Dong, Zili Zhang, Dabao Lao, Rongyi Ji, Weihu Zhou

Laser trackers are one of the most commonly used large-scale measurement systems in the ?elds of aircraft inspection, shipbuilding, automobile assembly, and other manufacturing sectors. Using a laser tracker can enable an operator to obtain an object’s spatial position through a combination of distance measurement and angle measurement. To realize distance measurement, traditional laser trackers use interferometry or phase ranging, each of which has its own strengths and weaknesses. Interferometry can achieve high-accuracy and high-frequency distance measurement, but it can only determine relative distances. Phase ranging can implement absolute distance measurement, however, its measuring frequency is limited due to its measuring principle. In this article a novel laser tracking measurement system is presented which realized high-frequency absolute distance measurement using a dual-femtosecond optical frequency comb with the accuracy of 0.5 ppm.

Celebrating 35 Years of the CMSC

Volume 14, Issue 1

Mike Richman

It’s true what they say: The more things change, the more they stay the same. When it comes to the world of metrology, those working in the field almost 40 years ago would surely recognize the landscape of the industry in 2019. Then, the question was about how to share best practices for the relatively small community of people working with portable equipment like theodolites and photogrammetry systems; today, the challenge is to reach beyond the walls of portable hardware, software, and peripherals and identify the commonalities that all metrologists share in a world where the twin pillars of data and automation rule. In both cases, the answer was, and is, the Coordinate Metrology Society, which began 35 years ago.

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.