06 Fakultät Luft- und Raumfahrttechnik und Geodäsie
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/7
Browse
5 results
Search Results
Item Open Access On the heritage of Kurt Magnus in gyro technology(2024) Wagner, Jörg F.Kurt Magnus (1912-2003) is one of the personalities who shaped research and teaching in applied mechanics during the 20th century. Through his work with his doctoral supervisor Max Schuler at the University of Göttingen, gyrodynamics became his most important field of work, which also led to his research in oscillations, multi‐body systems, and mechatronics. Magnus made significant contributions in all these fields. He was regarded as a gifted lecturer, and the close connection between scientific research and practical application was important to him. Life and scientific work of Kurt Magnus were, however, also characterized by his 7‐year deportation to the USSR in 1946. Despite this fate, he was able to continue his research under certain restrictions during this time. After returning to Germany, he became Professor of Mechanics at the University of Stuttgart in 1958. His appointment coincided with the gradual resumption of industrial activities in Germany in the field of gyro technology-activities that had come to a standstill at the end of World War II. In the years that followed, Magnus' institute became the scientific center for gyrodynamics in Germany. The activities of that time are reflected in a preserved collection of gyro instruments for research and teaching as well as in the co‐founding of an annual international conference on inertial technology, which continues to this day. Magnus' subsequent move to the Technical University of Munich in 1966 did nothing to change this. At that time, he was regarded as a doyen of gyro technology. After a short biography of Kurt Magnus, the paper addresses the recent revision and digitization of the gyro instrument collection and presents an outline of the history of the conference series providing details on how gyro technology has developed since his work in Stuttgart.Item Open Access Making historical gyroscopes alive - 2D and 3D preservations by sensor fusion and open data access(2021) Fritsch, Dieter; Wagner, Jörg F.; Ceranski, Beate; Simon, Sven; Niklaus, Maria; Zhan, Kun; Mammadov, GasimThe preservation of cultural heritage assets of all kind is an important task for modern civilizations. This also includes tools and instruments that have been used in the previous decades and centuries. Along with the industrial revolution 200 years ago, mechanical and electrical technologies emerged, together with optical instruments. In the meantime, it is not only museums who showcase these developments, but also companies, universities, and private institutions. Gyroscopes are fascinating instruments with a history dating back 200 years. When J.G.F. Bohnenberger presented his machine to his students in 1810 at the University of Tuebingen, Germany, nobody could have foreseen that this fascinating development would be used for complex orientation and positioning. At the University of Stuttgart, Germany, a collection of 160 exhibits is available and in transition towards their sustainable future. Here, the systems are digitized in 2D, 2.5D, and 3D and are made available for a worldwide community using open access platforms. The technologies being used are computed tomography, computer vision, endoscopy, and photogrammetry. We present a novel workflow for combining voxel representations and colored point clouds, to create digital twins of the physical objects with 0.1 mm precision. This has not yet been investigated and is therefore pioneering work. Advantages and disadvantages are discussed and suggested work for the near future is outlined in this new and challenging field of tech heritage digitization.Item Open Access Reevaluation of algorithmic basics for ZUPT-based pedestrian navigation(2022) Wagner, Jörg F.; Kohl, Michael; Györfi, BenediktDuring the last 10 to 15 years, pedestrian navigation based on zero velocity updates (ZUPT) has become very popular. One of the main reasons for this is the increasing availability of small, low-cost inertial measurement units. However, the processing of the data from these units for pedestrian navigation is almost exclusively based on algorithmic features that originate from classical inertial navigation with high-grade sensors. In addition, the historical background of the ZUPT approach presupposes also sensors with high accuracy. This leads to the problem that neither the ZUPT approach nor the algorithmic features mentioned are consistent with the accuracy level of the inertial measurement units used normally for pedestrian navigation. Therefore, the question arises of whether the usual algorithmic basics and numerical procedures employed by ZUPT-based pedestrian navigation are adequate. Supported by a literature review showing the state of the art, this study investigates the effect of basics such as the system states and the usage of Runge-Kutta method on the navigation accuracy from pedestrian inertial data aided by ZUPT. To this end, a comparative processing of a well-known, published dataset of a short walk and of own data from the authors using different data fusion algorithms was employed. The important results of this study are that the often-used omission of inertial sensor biases cannot be recommended, that a continuous-discrete Kalman filter in combination with a Runge-Kutta algorithm performs better than traditional filter configurations, and that total navigation states are an interesting alternative to classical navigation error-states.Item Open Access Integration of geometric computer vision, endoscopy and computed tomography for 3D modeling of gyroscopic instruments(2022) Zhan, Kun; Fritsch, Dieter (Prof. Dr.-Ing. habil. Prof. h. c.)3D digitization is of vital importance for cultural heritage assets for modern civilizations regarding safekeeping and promotion. Generally, cultural heritage indicates old buildings, ancient status or unearthed relics for the public. However, the objectives to be digitized also include tools and instruments that have been widely applied in the past decades, even though they have been replaced with more advanced technologies. We call these technical instruments and artifacts Tech Heritage (TH). Gyroscopes are one group of such fascinating instruments with a history dating back to 200 years. The main characteristics of gyroscopes regarding 3D digitization are (1) having highly complex structure; (2) consisting of different materials; (3) not only the surfaces but also the internal structures are important. All these features decide that no single methodology could meet the demand for their 3D digitization. To fulfill the requirements of gyroscopes in our research, photogrammetry, endoscopy and Computed Tomography (CT) are introduced for complete 3D digitization. With colored point clouds or textured meshes as result, photogrammetry is mainly for the global surface reconstruction of the object. For some cavities, holes or other parts that the regular camera hardly has access to, endoscopy is applied for a local 3D reconstruction, as supplement. As internal structures are also important, X-Ray computed tomography is utilized for volumetric 3D digitization. These three 3D sensor data should then be integrated for a complete 3D model. Additionally, the registration method should be adaptive to the data characteristics such as the geometry, point cloud density, etc. In this thesis, 3D reconstructions with each method as well as the data fusion are investigated. 1. Firstly, we study the stability and reliability of camera calibration before 3D reconstruction with photogrammetry and endoscopy. As the standard pre-calibration solution, Zhang's method suffers from the instability due to the correlations between the calibration parameters. To reduce this effect, the image configuration should be well considered with adequate oblique angles, distance difference as well as roll angels for a convergent image block. In our research, a quantitative analysis is implemented by a statistical approach using large bundles of images and get calibrations from randomly chosen image subsets. In addition, the recovered expected values of parameters are utilized as ground truth to scrutinize the single influencing factors of the imaging configuration. 2. Secondly, the 3D reconstruction processes are investigated with practical implementations. For the endoscope 3D reconstruction, the data acquisition process is the first challenge resulting from the image blur which may caused by the hand shaking as well as the small overlap. The imaging assistant setup and a mixture of image and video strategy are the methods adopted in our research as the solution. With the accurate calibration information and the improved image quality and configuration, we optimize the entire process through optimization of the Structure-from-Motion (SfM) method. As for CT 3D reconstruction, a stack of X-ray images, carrying the information of attenuation, is to be collected from different perspectives of the object. All reconstructed slices are integrated into an uniform 3D coordinate system to construct the complete 3D volumetric representation. 3. Thirdly, data registration methods are proposed regarding different data features. To register these two 3D data with few overlaps such as photogrammetry and endoscopic point clouds, a Gauss-Helmert model with manually picked control points is applied for transformation estimation with precision assessments. To take advantage of the pair-wise point cloud registration research, CT point cloud conversion and surface extraction are implemented from the volumetric CT data. As for the CT and photogrammetry data registration, it could be divided into two cases regarding the completeness of the CT surface representation. If the surface material is completely indicated in the CT data, we could directly project the color information from photogrammetric images to the CT surface after both datasets are transformed into the same coordinate system. In this way, we combine the high precision of CT data with the rich texture information. While low density surface material causes an incomplete representation of the CT surface, the transformation is estimated via the primitive based virtual control points from both surface data. With the determined transformation, the photogrammetric model could then be integrated with the CT model for a complete 3D representation. 4. Finally, in terms of 3D model expression, point clouds are of too big data volume if precision is required and have limited interaction possibilities. Therefore, the point clouds need to be vectorized into Constructive Solid Geometry (CSG) models to enable easier human-computer interaction. This process could be precisely done via manual work with sufficient caution via a Random Sample Consensus (RANSAC)-based geometric fitting process or even with a deep learning strategy via an end-to-end trained framework. The vectorized 3D model could be applied in AR/VR related applications to make full use of the work of 3D digitization. For the first time, three totally different sensors are studied for a fused 3D reconstruction in this research. Among the workflow, the practical application of endoscopy is fully investigated. The integration methods are adaptively designed according to the characteristics of each sensor as well as of the reconstructed object. It provides more possibilities and ideas for the digital tasks of different types of cultural heritage.Item Open Access Orientierung im Raum - 200 Jahre Maschine von Bohnenberger : Ausstellung im Foyer Universitätsbibliothek Stuttgart, 10. Dezember 2010 bis 29. Januar 2011(Stuttgart: Universität Stuttgart, Organisationsteam Bohnenberger, 2010) Hügel, Hubert; Fritsch, Dieter; Wagner, Jörg; Brullo, Giovanni; Hügel, Hubert; Eickholt, Mechthild (Grafik)Die Broschüre dokumentiert die Ausstellung in der Universitätsbibliothek Stuttgart, die aus Anlass des Jubiläums "200 Jahre Maschine von Bohnenberger" vom 10. Dezember 2010 bis 29. Januar 2011 zu sehen war.