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Search Publications by: Bala Muralikrishnan (Fed)

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Displaying 51 - 75 of 88

A Method of Determining Sphere Center to Center Distance Using Laser Trackers For Evaluating Laser Scanners.

November 11, 2014
Author(s)
Prem K. Rachakonda, Balasubramanian Muralikrishnan, Vincent D. Lee, Daniel S. Sawyer, Steven D. Phillips, John Palmateer
The Dimensional Metrology Group (DMG) at the National Institute of Standards and Technology (NIST) is involved in the development of documentary standards for volumetric performance evaluation of laser scanners. Typical evaluation of these scanners

Laser scanner two-face errors on spherical targets

November 11, 2014
Author(s)
Balasubramanian Muralikrishnan, Katharine M. Shilling, Daniel S. Sawyer, Prem K. Rachakonda, Vincent D. Lee, Steven D. Phillips, Geraldine S. Cheok, Kamel S. Saidi
Geometric misalignments within the construction of a laser scanner such as offsets, tilts, and eccentricities, result in systematic errors in the measured point coordinates (range and angles). Many of these sources of error are sensitive to two-face

POINT REMOVAL FOR FITTING SPHERES TO 3-D LASER SCANNER DATA

November 11, 2014
Author(s)
Katharine M. Shilling, Balasubramanian Muralikrishnan, Daniel S. Sawyer
The proliferation of laser scanners in a number of industries such as the metrology of large artifacts, digitization and reverse engineering, historical preservation and archiving has led to the need for documentary Standards to establish and compare the

A Proposed Interim Check for Field Testing a Laser Trackers 3-D Length Measurement Capability Using a Calibrated Scale Bar as a Reference Artifact

October 1, 2014
Author(s)
Vincent D. Lee, Christopher J. Blackburn, Balasubramanian Muralikrishnan, Daniel S. Sawyer, Mark Meuret, Aaron Hudlemeyer
This paper describes a proposed interim check for field testing a laser tracker’s 3-D length measurement capability using a calibrated scale bar as a reference artifact. The tests described here are constructed to be sensitive to uncompensated errors in

EVALUATION OF A LASER SCANNER FOR LARGE VOLUME COORDINATE METROLOGY - A COMPARISON OF RESULTS BEFORE AND AFTER FACTORY CALIBRATION

October 1, 2014
Author(s)
Massimiliano Ferrucci, Bala Muralikrishnan, Daniel S. Sawyer, Steven D. Phillips, Peter Petrov, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
Large volume laser scanners are increasingly being used for a variety of dimensional metrology applications. Methods to evaluate the performance of these scanners are still under development and there are currently no documentary standards available. This

Ranging Performance Evaluation of a Laser Scanner

October 20, 2013
Author(s)
Massimiliano M. Ferrucci, Balasubramanian Muralikrishnan, Christopher J. Blackburn, Daniel S. Sawyer, Steven D. Phillips, Vincent D. Lee, Peter Petrov, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
Large volume laser scanners are used for a variety of purposes, including dimensional metrology of large artifacts, digitization and reverse engineering, as well as historical preservation and archiving. In evaluating the performance of laser scanners, we

VOLUMETRIC PERFORMANCE EVALUATION OF A LASER SCANNER

October 20, 2013
Author(s)
Balasubramanian Muralikrishnan, Massimiliano M. Ferrucci, Daniel S. Sawyer, Grant Gerner, Vincent D. Lee, Christopher J. Blackburn, Steven D. Phillips, Peter Petrov, Yuri Yakovlev, Andrey Astrelin, Spike Milligan, John Palmateer
There are several sources of error in a laser scanner measurement. The optical and material properties of the target, the shape, form, surface texture, color, reflectivity, and orientation of the target in space, environmental effects, etc., all contribute

Two Applications of Small Feature Dimensional Measurements on a CMM with a Fiber Probe

September 4, 2013
Author(s)
Eric S. Stanfield, Bala Muralikrishnan, Theodore D. Doiron, Xiaoyu Alan Zheng, Shahram Orandi, david Duquette
We describe two interesting applications of dimensional measurements performed using a contact fiber probe on a commercial Coordinate Measuring Machine (CMM). Both examples involve artifacts that serve as material standards and contain features in the 100

The Effect of Tip Size in Calibration of Surface Roughness Specimens with Rectangular Profiles

September 2, 2013
Author(s)
Jun-Feng Song, Thomas B. Renegar, Johannes A. Soons, Balasubramanian Muralikrishnan, John S. Villarrubia, Xiaoyu A. Zheng, Theodore V. Vorburger
For the calibration of rectangular and trapezoidal profile roughness specimens, stylus tip will increase profile peak width and decrease valley width, which may cause the Ra changes (either increase or decrease, depends on the profile shape). Sometimes the

Applications of Profile Filtering in the Dimensional Metrology of Fuel Cell Plates

May 14, 2013
Author(s)
Balasubramanian Muralikrishnan, Wei Ren, Eric S. Stanfield, Dennis S. Everett, Xiaoyu A. Zheng, Theodore D. Doiron
We describe the application of several surface profile filters as an enabling tool in the dimensional measurements of an engineering artifact, namely, a fuel cell plate. We recently reported work on the development of a non-contact system for dimensional

High Accuracy Measurements Using a Scanning System with a Single Point Triangulation Sensor

May 13, 2013
Author(s)
Theodore D. Doiron, Wei Ren, Eric S. Stanfield, Balasubramanian Muralikrishnan, Christopher J. Blackburn
The capabilities of non-contact laser spot triangulation sensors for high accuracy measurements have slowly increased over the past decade, and now have usable resolution below 0.1 µm. The Dimensional Metrology Group has developed a simple scanning system

Assessing Ranging Errors as a Function of Azimuth in Laser Trackers and Tracers

April 18, 2013
Author(s)
Balasubramanian Muralikrishnan, Vincent D. Lee, Christopher J. Blackburn, Daniel S. Sawyer, Steven D. Phillips, Wei Ren, Ben Hughes
Tilt and radial error motion of a laser tracker head as it spins about the two axes results in small but measurable ranging and angle errors. The laser tracer, on the other hand, measures range with respect to the center of a high quality stationary sphere

A Model for Geometry-Dependent Errors in Length Artifacts

September 27, 2012
Author(s)
Daniel S. Sawyer, Brian Parry, Christopher J. Blackburn, Balasubramanian Muralikrishnan, Steven D. Phillips
We present a detailed model of dimensional changes in long length artifacts, such as step gauges and ball bars, due to bending under gravity. The comprehensive model is based on evaluation of the gauge points relative to the neutral bending surface. It

Stylus Tip-Size Effect on the Calibration of Periodic Roughness Specimens with Rectangular Profiles

March 21, 2012
Author(s)
Thomas B. Renegar, Johannes A. Soons, Balasubramanian Muralikrishnan, John S. Villarrubia, Xiaoyu A. Zheng, Theodore V. Vorburger, Jun-Feng Song
Stylus instruments are widely used for surface characterization. It is well known that the size and shape of the stylus tip affects the measured surface geometry and parameters. In most cases, increasing the tip size decreases the measured Ra value because

Performance Evaluation Experiments on a Laser Spot Triangulation Probe

November 25, 2011
Author(s)
Balasubramanian Muralikrishnan, Wei Ren, Dennis S. Everett, Eric S. Stanfield, Theodore D. Doiron
Laser triangulation probes are increasingly used for dimensional measurements in a variety of applications. At the National Institute of Standards and Technology, we have recently explored the use of laser spot triangulation probes to determine dimensional

NON-CONTACT DIMENSIONAL MEASUREMENTS OF BIPOLAR FUEL CELL PLATES

November 15, 2011
Author(s)
Balasubramanian Muralikrishnan, Wei Ren, Dennis S. Everett, Eric S. Stanfield, Theodore D. Doiron
Non-contact dimensional measurement of fuel cell plates is critical to the eventual rapid manufacture by supporting in-process measurement and control. This need has been identified by the Department of Energy’s Hydrogen Program, and by numerous

Dimensional Metrology of Bipolar Fuel Cell Plates Using Laser Spot Triangulation Probes

March 22, 2011
Author(s)
Balasubramanian Muralikrishnan, Wei Ren, Dennis S. Everett, Eric S. Stanfield, Theodore D. Doiron
As in any engineering component, manufacturing a bipolar fuel cell plate for a polymer electrolyte membrane (PEM) hydrogen fuel cell power stack to within its stated design tolerances is critical in achieving the intended function. In a bipolar fuel cell

Geometric effects when measuring small holes with micro contact probes.

March 1, 2011
Author(s)
Jack A. Stone Jr., Balasubramanian Muralikrishnan, Chittaranjan Sahay
A coordinate measuring machine with a suitably small probe can be used to measure micro-features such as the diameter and form of small holes (often about 100 micrometers in diameter). When measuring small holes, the clearance between the probe tip and the

Measuring Scale Errors in a Laser Tracker s Horizontal Angle Encoder through Simple Length Measurement and Two-face System Tests

November 1, 2010
Author(s)
Balasubramanian Muralikrishnan, Christopher J. Blackburn, Daniel S. Sawyer, Steven D. Phillips, Robert Bridges, Quan Ma
We describe a method to estimate the scale errors in the horizontal angle encoder of a laser tracker in this paper. The method does not require expensive instrumentation such as a rotary stage or even a calibrated artifact. An uncalibrated but stable

Micro-feature dimensional and form measurements with the NIST fiber probe on a CMM

July 30, 2010
Author(s)
Balasubramanian Muralikrishnan, Jack A. Stone Jr., John R. Stoup, Chittaranjan Sahay
The NIST fiber probe is a Coordinate Measuring Machine (CMM) probing system intended for diameter and form measurement of micro features and small holes. This Moore M48 CMM at NIST can measure holes down to 500 um diameter with the Movamatic probe; the

Choosing test positions for laser tracker evaluation and future Standards development

July 15, 2010
Author(s)
Balasubramanian Muralikrishnan, Daniel S. Sawyer, Christopher J. Blackburn, Steven D. Phillips, Craig M. Shakarji, Ed Morse, Robert Bridges
A working group within the ISO TC 213 committee is developing a draft document [11] for evaluating the performance of laser trackers. The ASME B89.4.19 Standard [1] and the draft VDI/VDE 2617 part 10 [2] describe some useful tests that are incorporated

RECIST vs. Volume Measurement in Medical CT Using Ellipsoids of Known Size

April 12, 2010
Author(s)
Zachary H. Levine, Bruce R. Borchardt, Nolan J. Brandenburg, Charles W. Clark, Balasubramanian Muralikrishnan, Craig M. Shakarji, Joseph J. Chen, Eliot L. Siegel
(a) Purpose: We wanted to test the extent to which two common methods of determining the sizes of tumors would perform when compared to a statistically significant number of well-characterized reference objects. The size of the objects was chosen to

Performance Evaluation and Metrics for Perception in Intelligent Manufacturing

December 31, 2009
Author(s)
Roger D. Eastman, Tsai H. Hong, Jane Shi, Tobias Hanning, Bala Muralikrishnan, S. S. Young, Tommy Chang
Real-time three-dimensional vision has been rapidly advancing over the past twenty years, leading to a number of successful laboratory demonstrations, including real-time visual servoing, autonomous vehicle navigation , and real-time people and vehicle
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