Publications

@conference{Pekel2023,

title = {Spherical acquisition trajectories for X-ray Computed Tomography with a robotic sample holder},

author = {E. Pekel, M. Dierolf, F. Pfeiffer, T. Lasser},

year  = {2023},

date = {2023-07-16},

urldate = {2023-07-16},

booktitle = {Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine (Fully 3D)},

address = {Stony Brook, USA},

abstract = {In this work we present an X-ray computed tomography setup that integrates a seven degree of freedom robotic arm as a sample holder. The path planning and robot control algorithms are optimized for seamless execution of spherical trajectories. A precision manufactured sample holder part is attached to the robotic arm for the calibration procedure. We present experimental results with the robotic sample holder where a sample measurement on a spherical trajectory achieves superior reconstruction quality compared to a conventional circular trajectory. The proposed system is a step towards higher image reconstruction quality in X-ray CT systems.},

keywords = {},

pubstate = {published},

tppubtype = {conference}

}

@conference{ctmeeting2022,

title = {Geometric calibration of seven degree of freedom robotic sample holder for x-ray CT},

author = {Erdal Pekel and Florian Schaff and Martin Dierolf and Franz Pfeiffer and Tobias Lasser},

url = {https://doi.org/10.1117/12.2646492},

doi = {10.1117/12.2646492},

year  = {2022},

date = {2022-10-17},

urldate = {2022-10-17},

booktitle = {7th International Conference on Image Formation in X-Ray Computed Tomography},

address = {Baltimore, USA},

abstract = {We present a geometric calibration method for integrating a seven degrees of freedom robotic arm as a sample holder within an existing laboratory X-ray computed tomography setup. We aim to provide a flexible sample holder that is able to execute non-standard and task-specific trajectories for complex samples. The calibration is necessary to identify the accurate pose of the sample which deviates from the expected pose due to inaccurate placement of the robotic arm. The robotic arm is integrated with a unified software package that allows for path planning, collision detection, geometric calibration and reconstruction of the sample. With our software the user is able to command the robotic arm to execute arbitrary trajectories for a given sample in a safe manner and output its reconstruction to the user. We present experimental results with a circular trajectory where the robotic sample holder achieves identical visual quality compared to a conventional sample holder.},

keywords = {},

pubstate = {published},

tppubtype = {conference}

}

@conference{ctmeeting2020,

title = {X-ray Computed Tomography with a Robotic Sample Holder},

author = {Erdal Pekel and Martin Dierolf and Franz Pfeiffer and Tobias Lasser},

url = {https://ct-meeting.org/wp-content/uploads/2021/11/ProceedingsCTMeeting2020.pdf},

year  = {2020},

date = {2020-08-03},

urldate = {2020-08-03},

booktitle = {International Conference on Image Formation in X-ray Computed Tomography (CT Meeting)},

address = {Regensburg, Germany},

abstract = {In this work we present the integration of a robotic arm with seven degrees of freedom as a sample holder within an experimental X-ray computed tomography setup. The robot enables arbitrary rotations of the sample and hence different non-standard acquisition trajectories that are not possible with conventional sample holding mechanisms. Our framework provides a programmatic interface for trajectory inputs and their motion planning, a robotic arm calibration mechanism for accurate target placement utilizing a single RGB camera, and both passive and active collision detection mechanisms based on a set of depth cameras. We elaborate on the challenges of precisely positioning samples into the X-ray beam and propose a method together with a discussion on its current limitations, in particular in view of performing X-ray computed tomography.},

keywords = {},

pubstate = {published},

tppubtype = {conference}

}