Related Experiment Video
Updated: Mar 16, 2026
07:58
Automatic Laser-based Geometry Capture for Finite Element Analysis of Weld Beads
Published on: July 25, 2025
1.0K
ASME B89.4.19 Performance Evaluation Tests and Geometric Misalignments in Laser Trackers.
B Muralikrishnan1, D Sawyer1, C Blackburn1
1Precision Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Summary
This study analyzes how laser tracker misalignments affect measurements. New tests are proposed to better detect these errors, improving the accuracy of laser tracker performance evaluations.
Area of Science:
- Metrology
- Optical Engineering
- Mechanical Engineering
Background:
- Laser trackers are susceptible to systematic errors from mechanical and optical component misalignments.
- These errors impact spherical coordinate measurements (angles, range) and artifact length calculations.
- Current ASME B89.4.19 Standard tests aim to identify these geometric misalignments.
Purpose of the Study:
- To analyze the sensitivity of ASME B89.4.19 Standard tests to laser tracker misalignments.
- To propose novel length measurement system tests with enhanced sensitivity to misalignments.
- To validate proposed tests through experimental results.
Main Methods:
- Utilizing error models and numerical simulations to assess test sensitivity.
- Evaluating the performance of existing length measurement system and two-face system tests.
- Conducting experimental validation with a misaligned laser tracker.
Main Results:
- Identified specific misalignments and their impact on laser tracker measurements.
- Demonstrated that proposed new length measurement tests exhibit improved sensitivity to certain misalignments.
- Experimental data confirmed the effectiveness of the proposed tests in detecting misalignments.
Conclusions:
- Existing ASME B89.4.19 Standard tests can be improved for misalignment detection.
- The proposed length measurement system tests offer a more sensitive approach to identifying geometric errors.
- Accurate performance evaluation of laser trackers requires robust tests sensitive to systematic misalignments.
Related Concept Videos
01:18Errors in Taping
417
Errors in taping arise from multiple factors that can significantly impact measurement accuracy in surveying. Misalignment of the tape, often due to human error, is one primary source. A skilled rear tapeman, using a telescope, can help correct alignment by guiding the head tapeman; however, human limitations still lead to small inaccuracies. These errors may include misplacement of pins or inaccurate tape readings due to common visual confusions, such as mistaking a six for a nine. Such...
417
01:12Adjusting a Traverse
420
In the site survey of a four-sided traverse, internal angles are essential to ensure geometric accuracy. The survey revealed that the sum of the measured internal angles was 359 degrees and 48 minutes, which is 12 minutes less than the expected 360 degrees. This discrepancy signals an error likely arising from measurement inaccuracies during the fieldwork.To rectify this error, the adjustment process involved distributing the 12-minute shortfall equally across the four internal angles. By...
420
01:17Common Leveling Mistakes and Errors
568
A survey team is tasked with determining the elevation difference between points Point A and Point B, separated by uneven terrain. They use a leveling instrument and a leveling rod.Common MistakesMisreading the Rod: During a backsight reading at Point A, the instrumentman observes the rod partially obscured by tall grass. Instead of reading 1.135 m, they mistakenly record 1.735 m due to the misalignment of the crosshair with the wrong graduation. This error adds 0.600 m to all subsequent...
568
01:10Design Example: Measuring Distance Between Two Points with Obstructions
472
When measuring distances in areas with physical obstructions, such as a lake in a field, surveyors must employ techniques to calculate accurate lengths without direct line measurements. One effective method is the offset technique, which allows for precise distance estimation over inaccessible stretches.In this scenario, a surveyor must measure a side of an area that crosses a lake. Since the measuring tape cannot span the lake, the surveyor begins by establishing a baseline that aligns with...
472