3,906 research outputs found
Automated Optical Inspection and Image Analysis of Superconducting Radio-Frequency Cavities
The inner surface of superconducting cavities plays a crucial role to achieve
highest accelerating fields and low losses. For an investigation of this inner
surface of more than 100 cavities within the cavity fabrication for the
European XFEL and the ILC HiGrade Research Project, an optical inspection robot
OBACHT was constructed. To analyze up to 2325 images per cavity, an image
processing and analysis code was developed and new variables to describe the
cavity surface were obtained. The accuracy of this code is up to 97% and the
PPV 99% within the resolution of 15.63 . The optical obtained
surface roughness is in agreement with standard profilometric methods. The
image analysis algorithm identified and quantified vendor specific fabrication
properties as the electron beam welding speed and the different surface
roughness due to the different chemical treatments. In addition, a correlation
of with a significance of between an obtained
surface variable and the maximal accelerating field was found
Experimental setup for the investigation of reproducibility of novel tool changing systems in nanofabrication machines
Nanomeasuring machines developed at the Technische Universität Ilmenau enable three-dimensional measurements and manufacturing processes with the lowest uncertainties. Due to the requirements for these processes, a highly reproducible and long-term stable tool changing system is needed. For this purpose, kinematically determined couplings are widely used. The state-of-the-art investigations on those are not sufficient for the highest demands on the reproducibility required for this application. A theoretical determination of the reproducibility based on analytical or numerical methods is possible, however not in the desired nanometer range. Due to this, a measurement setup for the determination of the reproducibility in five degrees of freedom with nanometer uncertainty was developed. First, potential measuring devices are systematically examined and measurement principles were developed out of this. A three-dimensional vector-based uncertainty analysis is performed to prove the feasibility of the measurement principle and provides a basis for further design. As a result, a translatory measurement uncertainty of 10 nm and a rotatory uncertainty of 11 nrad can be reached. Afterwards, the measurement setup is designed, focusing on the metrological frame and the lift-off device. The developed setup exceeds the uncertainties of the measurement setups presented in the state-of-the-art by an order of magnitude, allowing new in-depth investigations of the reproducibility of kinematic couplings
A continuum robotic platform for endoscopic non-contact laser surgery: design, control, and preclinical evaluation
The application of laser technologies in surgical interventions has been accepted in the clinical
domain due to their atraumatic properties. In addition to manual application of fibre-guided
lasers with tissue contact, non-contact transoral laser microsurgery (TLM) of laryngeal tumours
has been prevailed in ENT surgery. However, TLM requires many years of surgical training
for tumour resection in order to preserve the function of adjacent organs and thus preserve the
patient’s quality of life. The positioning of the microscopic laser applicator outside the patient
can also impede a direct line-of-sight to the target area due to anatomical variability and limit
the working space. Further clinical challenges include positioning the laser focus on the tissue
surface, imaging, planning and performing laser ablation, and motion of the target area during
surgery. This dissertation aims to address the limitations of TLM through robotic approaches and
intraoperative assistance. Although a trend towards minimally invasive surgery is apparent, no
highly integrated platform for endoscopic delivery of focused laser radiation is available to date.
Likewise, there are no known devices that incorporate scene information from endoscopic imaging
into ablation planning and execution. For focusing of the laser beam close to the target tissue, this
work first presents miniaturised focusing optics that can be integrated into endoscopic systems.
Experimental trials characterise the optical properties and the ablation performance. A robotic
platform is realised for manipulation of the focusing optics. This is based on a variable-length
continuum manipulator. The latter enables movements of the endoscopic end effector in five
degrees of freedom with a mechatronic actuation unit. The kinematic modelling and control of the
robot are integrated into a modular framework that is evaluated experimentally. The manipulation
of focused laser radiation also requires precise adjustment of the focal position on the tissue. For
this purpose, visual, haptic and visual-haptic assistance functions are presented. These support
the operator during teleoperation to set an optimal working distance. Advantages of visual-haptic
assistance are demonstrated in a user study. The system performance and usability of the overall
robotic system are assessed in an additional user study. Analogous to a clinical scenario, the
subjects follow predefined target patterns with a laser spot. The mean positioning accuracy of the
spot is 0.5 mm. Finally, methods of image-guided robot control are introduced to automate laser
ablation. Experiments confirm a positive effect of proposed automation concepts on non-contact
laser surgery.Die Anwendung von Lasertechnologien in chirurgischen Interventionen hat sich aufgrund der atraumatischen Eigenschaften in der Klinik etabliert. Neben manueller Applikation von fasergeführten
Lasern mit Gewebekontakt hat sich die kontaktfreie transorale Lasermikrochirurgie (TLM) von
Tumoren des Larynx in der HNO-Chirurgie durchgesetzt. Die TLM erfordert zur Tumorresektion
jedoch ein langjähriges chirurgisches Training, um die Funktion der angrenzenden Organe zu
sichern und damit die Lebensqualität der Patienten zu erhalten. Die Positionierung des mikroskopis chen Laserapplikators außerhalb des Patienten kann zudem die direkte Sicht auf das Zielgebiet
durch anatomische Variabilität erschweren und den Arbeitsraum einschränken. Weitere klinische
Herausforderungen betreffen die Positionierung des Laserfokus auf der Gewebeoberfläche, die
Bildgebung, die Planung und Ausführung der Laserablation sowie intraoperative Bewegungen
des Zielgebietes. Die vorliegende Dissertation zielt darauf ab, die Limitierungen der TLM durch
robotische Ansätze und intraoperative Assistenz zu adressieren. Obwohl ein Trend zur minimal
invasiven Chirurgie besteht, sind bislang keine hochintegrierten Plattformen für die endoskopische
Applikation fokussierter Laserstrahlung verfügbar. Ebenfalls sind keine Systeme bekannt, die
Szeneninformationen aus der endoskopischen Bildgebung in die Ablationsplanung und -ausführung
einbeziehen. Für eine situsnahe Fokussierung des Laserstrahls wird in dieser Arbeit zunächst
eine miniaturisierte Fokussieroptik zur Integration in endoskopische Systeme vorgestellt. Experimentelle Versuche charakterisieren die optischen Eigenschaften und das Ablationsverhalten. Zur
Manipulation der Fokussieroptik wird eine robotische Plattform realisiert. Diese basiert auf einem
längenveränderlichen Kontinuumsmanipulator. Letzterer ermöglicht in Kombination mit einer
mechatronischen Aktuierungseinheit Bewegungen des Endoskopkopfes in fünf Freiheitsgraden.
Die kinematische Modellierung und Regelung des Systems werden in ein modulares Framework
eingebunden und evaluiert. Die Manipulation fokussierter Laserstrahlung erfordert zudem eine
präzise Anpassung der Fokuslage auf das Gewebe. Dafür werden visuelle, haptische und visuell haptische Assistenzfunktionen eingeführt. Diese unterstützen den Anwender bei Teleoperation
zur Einstellung eines optimalen Arbeitsabstandes. In einer Anwenderstudie werden Vorteile der
visuell-haptischen Assistenz nachgewiesen. Die Systemperformanz und Gebrauchstauglichkeit
des robotischen Gesamtsystems werden in einer weiteren Anwenderstudie untersucht. Analog zu
einem klinischen Einsatz verfolgen die Probanden mit einem Laserspot vorgegebene Sollpfade. Die
mittlere Positioniergenauigkeit des Spots beträgt dabei 0,5 mm. Zur Automatisierung der Ablation
werden abschließend Methoden der bildgestützten Regelung vorgestellt. Experimente bestätigen
einen positiven Effekt der Automationskonzepte für die kontaktfreie Laserchirurgie
Map building fusing acoustic and visual information using autonomous underwater vehicles
Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Journal of Field Robotics 30 (2013): 763–783, doi:10.1002/rob.21473.We present a system for automatically building 3-D maps of underwater terrain fusing
visual data from a single camera with range data from multibeam sonar. The six-degree
of freedom location of the camera relative to the navigation frame is derived as part of the
mapping process, as are the attitude offsets of the multibeam head and the on-board velocity
sensor. The system uses pose graph optimization and the square root information smoothing
and mapping framework to simultaneously solve for the robot’s trajectory, the map, and
the camera location in the robot’s frame. Matched visual features are treated within the
pose graph as images of 3-D landmarks, while multibeam bathymetry submap matches are
used to impose relative pose constraints linking robot poses from distinct tracklines of the
dive trajectory. The navigation and mapping system presented works under a variety of
deployment scenarios, on robots with diverse sensor suites. Results of using the system to
map the structure and appearance of a section of coral reef are presented using data acquired
by the Seabed autonomous underwater vehicle.The work described herein was funded by the National Science Foundation Censsis ERC under grant number
EEC-9986821, and by the National Oceanic and Atmospheric Administration under grant number
NA090AR4320129
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