---
_id: '61825'
abstract:
- lang: eng
text: "Abstract\r\n Industrial x-ray
computed tomography (CT) systems with high geometric flexibility are increasingly
utilized for large-scale measurement objects or challenging measurement tasks.
To maintain high accuracy when deviating from the established circular scan trajectory,
trajectory calibration methods using multi-sphere reference objects with known
marker positions are commonly employed. These multi-sphere objects can either
be scanned together with the measurement object (online trajectory calibration)
or in a separate scan (offline trajectory calibration). While offline calibration
increases machine time, it generally results in higher scan quality. However,
a sufficient pose repeatability is necessary to ensure comparable or even superior
accuracy to online calibration. In this contribution, we present a straightforward
procedure to compare both types of trajectory calibration in a way that the differences
of the results can directly be traced back to the influence of the pose repeatability.
The multi-sphere reference object is not only used for trajectory calibration,
but simultaneously as a measurement object for repeated measurements. The methodology
is tested on both a twin robotic CT system and a conventional CT system that is
additionally equipped with a hexapod manipulator for adaptive object tilting.
Results showed, independent from the type of trajectory calibration, systematic
measurement errors in the order of 10−5–10−4
of measured sphere distances and sphericity values below 50 \r\n
\ \r\n \r\n \r\n \r\n
\ μ\r\n \r\n
\ \r\n m\r\n \r\n
\ \r\n \r\n .
For sphere distances, random errors were increased by a factor of 5 due to the
offline trajectory calibration, but were still low (\r\n
\ \r\n \r\n \r\n \r\n
\ <\r\n \r\n
\ \r\n 1\r\n
\ \r\n \r\n \r\n μ\r\n
\ \r\n \r\n
\ m\r\n \r\n
\ \r\n \r\n )
in comparison to systematic errors and the spread of different measurement features.
Overall, both investigated systems demonstrated sufficient positioning repeatability
for offline trajectory calibration. The method is in general also applicable to
any other types of manipulator systems used for CT devices. It provides a workflow
for the decision which type of trajectory calibration is preferable for a given
CT system."
article_number: '025401'
author:
- first_name: Lorenz
full_name: Butzhammer, Lorenz
last_name: Butzhammer
- first_name: Niklas
full_name: Handke, Niklas
last_name: Handke
- first_name: Simon
full_name: Wittl, Simon
last_name: Wittl
- first_name: Gabriel
full_name: Herl, Gabriel
last_name: Herl
- first_name: Tino
full_name: Hausotte, Tino
last_name: Hausotte
citation:
ama: Butzhammer L, Handke N, Wittl S, Herl G, Hausotte T. Direct assessment of the
influence of pose repeatability on the accuracy of dimensional measurements for
computed tomography systems with high degrees of freedom. Measurement Science
and Technology. 2025;36(2). doi:10.1088/1361-6501/ada05a
apa: Butzhammer, L., Handke, N., Wittl, S., Herl, G., & Hausotte, T. (2025).
Direct assessment of the influence of pose repeatability on the accuracy of dimensional
measurements for computed tomography systems with high degrees of freedom. Measurement
Science and Technology, 36(2), Article 025401. https://doi.org/10.1088/1361-6501/ada05a
bibtex: '@article{Butzhammer_Handke_Wittl_Herl_Hausotte_2025, title={Direct assessment
of the influence of pose repeatability on the accuracy of dimensional measurements
for computed tomography systems with high degrees of freedom}, volume={36}, DOI={10.1088/1361-6501/ada05a},
number={2025401}, journal={Measurement Science and Technology}, publisher={IOP
Publishing}, author={Butzhammer, Lorenz and Handke, Niklas and Wittl, Simon and
Herl, Gabriel and Hausotte, Tino}, year={2025} }'
chicago: Butzhammer, Lorenz, Niklas Handke, Simon Wittl, Gabriel Herl, and Tino
Hausotte. “Direct Assessment of the Influence of Pose Repeatability on the Accuracy
of Dimensional Measurements for Computed Tomography Systems with High Degrees
of Freedom.” Measurement Science and Technology 36, no. 2 (2025). https://doi.org/10.1088/1361-6501/ada05a.
ieee: 'L. Butzhammer, N. Handke, S. Wittl, G. Herl, and T. Hausotte, “Direct assessment
of the influence of pose repeatability on the accuracy of dimensional measurements
for computed tomography systems with high degrees of freedom,” Measurement
Science and Technology, vol. 36, no. 2, Art. no. 025401, 2025, doi: 10.1088/1361-6501/ada05a.'
mla: Butzhammer, Lorenz, et al. “Direct Assessment of the Influence of Pose Repeatability
on the Accuracy of Dimensional Measurements for Computed Tomography Systems with
High Degrees of Freedom.” Measurement Science and Technology, vol. 36,
no. 2, 025401, IOP Publishing, 2025, doi:10.1088/1361-6501/ada05a.
short: L. Butzhammer, N. Handke, S. Wittl, G. Herl, T. Hausotte, Measurement Science
and Technology 36 (2025).
date_created: 2025-10-14T13:50:32Z
date_updated: 2026-02-12T10:45:36Z
department:
- _id: '630'
doi: 10.1088/1361-6501/ada05a
intvolume: ' 36'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://iopscience.iop.org/article/10.1088/1361-6501/ada05a/pdf
oa: '1'
project:
- _id: '130'
name: 'TRR 285: Methodenentwicklung zur mechanischen Fügbarkeit in wandlungsfähigen
Prozessketten'
- _id: '133'
name: TRR 285 - Project Area C
- _id: '149'
name: TRR 285 - Subproject C05
publication: Measurement Science and Technology
publication_identifier:
issn:
- 0957-0233
- 1361-6501
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
status: public
title: Direct assessment of the influence of pose repeatability on the accuracy of
dimensional measurements for computed tomography systems with high degrees of freedom
type: journal_article
user_id: '93720'
volume: 36
year: '2025'
...