TY - CHAP A1 - Zentgraf, Peter A1 - Berge, S. A1 - Edfors, A. A1 - Olsson, T. A1 - Pionnier, G. A1 - Björk, M. A1 - Chasset, C. A1 - Nordebäck, T. A1 - Rieschel, M. A1 - Lübke- Ossenbeck, B. T1 - Advanced AOCS Design on the First Small GEO Telecom Satellite T2 - 60th International Astronautical Congress, Oct. 12 -16, 2009, Daejon, South Korea N2 - The advanced Attitude and Orbit Control System (AOCS) design of the Small GEO platform is now being adapted for the first commercial mission. The Small GEO telecommunications satellite is a new development to fill a niche in the telecom industry for small platforms weighing about 1.5 tonnes and targeting payloads of 300 kg and 3 kW. The first mission will launch into Geostationary Transfer Orbit (GTO). Small GEO is being developed by a Consortium led by OHBSystem AG. The Swedish Space Corporation is a partner in the Consortium and supplies the AOCS and Electric Propulsion (EP) subsystems. The project is currently in Phase C and the first mission will fly in 2012. This article gives an overview of the AOCS development status. The AOCS architecture is a three-axis stabilized system using reaction wheels for attitude control, star trackers for attitude determination, and EP for orbit control. The AOCS software is being developed using model-based design techniques and test driven development. Results from subsystem level testing of flight code will be presented. The AOCS design is characterized by a number of advances in technology beyond traditional telecom satellite designs. Perhaps the largest deviation from a traditional design is complete reliance on EP for orbit control. Angular momentum management of the reaction wheels relies solely upon EP in the nominal modes. The EP is not used in the safe modes and therefore a cold gas system is included On-board. The cold gas system uses Xenon, the same fuel used by the EP. Another advance is the reliance upon APS-based star trackers. APS (Active Pixel Sensor) star trackers have a number of advantages over their CCD-based cousins in terms of robustness. The traditional fine sun sensor is simplified to a fault tolerant system of solar cells giving low, but more than adequate, accuracy. In addition, a GPS sensor will be flown on-board as an experiment. KW - AOCS (Attitude and orbit control system) design KW - Small Geo Telecom Satellite Y1 - 2018 ER - TY - JOUR A1 - Zentgraf, Peter A1 - Bernatzky, Andreas A1 - Hager, Ralf A1 - Heigl, Martin A1 - Huber, Michaela A1 - Vogl, Georg A1 - Wolf, Christopher A1 - Zeitler, Adrian T1 - Hagelnavigator RO-BERTA für ein Hagelabwehrflugzeug JF - CRISIS PREVENTION Das Fachmagazin für Gefahrenabwehr, Innere Sicherheit und Katastrophenhilfe KW - Hagel Y1 - 2021 VL - 2021 IS - 2 SP - 38 EP - 40 ER - TY - GEN A1 - Zentgraf, Peter A1 - Erb, S. ED - Zentgraf, Peter T1 - IMPACT OF ELECTRIC PROPULSION UNCERTAINTY ON ORBIT PREDICTION N2 - This paper analyses the achievable performance of the orbit prediction for a geostationary satellite using clusters of electrical propulsion (EP) thrusters for station-keeping and a star tracker based attitude control system. The challenge in the orbit prediction is that the real electrical propulsion thrust is known with limited accuracy only. In combination with thrust pointing errors, these inaccuracies can accumulate to large orbit position errors during long low thrust burn arcs. The discrepancy between real and predicted satellite position is determined in terms of probability and as a worst case scenario. KW - Orbit prediction KW - Electric propulsion KW - Satellite position Y1 - 2018 ER - TY - JOUR A1 - Zentgraf, Peter A1 - Huber, Michaela T1 - Störgrößenkompensation in geregelten Systemen - Eine einfache Methode T1 - Compensating for disturbances in control systems - Demonstrating the practical benefits of a simple method JF - atp magazin N2 - Ein gutes Modell der Regelstrecke erhöht die Erfolgsaussicht, eine in der Simulation gut funktionierende Regelung in der Praxis genauso gut betreiben zu können. Gute Modelle eröffnen auch noch weitere Perspektiven: Sind die störenden Einflüsse auf den Regelkreis, die Störgrößen, die Messfehler und die Ungenauigkeiten im Simulationsmodell insgesamt kleiner als die Genauigkeitsanforderungen an die Regelgröße, dann kann man durch entsprechende Filterung des Eingangssignals sogar auf eine Rückführung der Regelgröße sogar verzichten. Andernfalls lassen sich deren Auswirkung auf die Regelgröße durch eine Rückführung verkleinern. Der Prozess kann für schnelle und hochgenaue Anwendungen durch die vorgestellte Methode weiter verbessert werden, wenn die störenden Einflüsse auf den Regelkreis direkt geschätzt und gleich kompensiert werden, bevor sie sich in der Regelgröße bemerkbar machen können. N2 - Control design engineers prefer precise models of a plant because these increase the chances to successfully transfer the design from simulation to reality. Furthermore, if the influence of disturbances, the noise content of the signals, and the model inaccuracy are small enough, then an open loop control might be sufficient. Otherwise, a feedback control loop is required to reduce the impact of the disturbances on the controlled variable. Using the method presented here, the time needed to reduce the impact during the process can be shortened significantly by directly estimating and compensating for the effects caused by disturbances and noise before these become noticeable in the controlled variable. KW - Regelstrecke KW - Regelkreis Y1 - 2022 VL - 2022 IS - 04 ER - TY - CHAP A1 - Zentgraf, Peter A1 - Reggio, D. T1 - MAGNETIC RATE DAMPING FOR SATELLITES IN LEO T2 - 32nd ANNUAL AAS GUIDANCE AND CONTROL CONFERENCE N2 - This article deals with the topic of damping the rates of a satellite after separation from the launcher by sensing the rates with magnetometers or gyroscopes and actually damping it with torquerods or thrusters. In literature problems of this kind are treated by linearization which is not adequate here due to the high nonlinearity of the problem caused by the high gyroscopic torque. This paper addresses the observability and controllability of the rate dynamics for symmetric satellite bodies. Furthermore, robust stability of any bodies is investigated by means of the Krasovskii–LaSalle principle which is a variant of Ljapunov’s Second Method. It is found that – apart from one exception - the system is robustly stable for certain conditions depending only on the gain matrix and not depending on the orbit, moments of inertia or initial conditions. The exception is that of the intuitive case of an equator type orbit, in which the satellite rotates around the magnetic field lines, in this case the satellite’s rate cannot be damped. Several design configurations are analysed with respect to their performance and cost: Rate damping with magnetometers or gyroscopes as sensors, and torquerods and thrusters as actuators. The results are evaluated with respect to the time to reach the desired rate, the propellant and the power equivalent battery mass used. The goal is to use the results to allow an AOCS equipment and architecture trade-off at an early project phase. The design of the rate damping control of the SWARM project is presented as an example and demonstrated with simulations. KW - Magnetic Rate Damping KW - Satellites KW - symmetric satellite bodies Y1 - 2018 ER - TY - CHAP A1 - Zenz, Vitus A1 - Muscat, Dirk A1 - Strübbe, Nicole T1 - Development of a new granulate feeding system for gas pressurized extrusion processes T2 - ANTEC 2023 N2 - One major problem of a continuous process like plastic extrusion is their incapability to deal with non-local gas pressure. This is an inherent problem because a continuous process has an open end in the feeding port where pressure can escape. In this study a novel feeding system was developed to enable granulate feeding into gas pressurized processes inside a single- or twin-screw extruder. With this apparatus gas pressure can be applied inside the extrusion process. The apparatus separates the pressurized extruder from the dosing equipment that feeds the extruder. It keeps the pressure inside the system while continuously feeding new material into the process. A small-scale prototype was designed for proof-of concept. The small size of the prototype was able to handle small amounts of granulates of around 100 - 200 g/h. An applied gas pressure of 8 bar was achieved. In future optimizations, throughput can be increased and maximum applied gas pressure towards 15-20 bar. KW - Plastic feeding KW - Granulate KW - Extrusion KW - Compounding KW - Reactive Extrusion Y1 - 2023 PB - SPE ANTEC ER - TY - JOUR A1 - Zenz, Vitus A1 - Muscat, Dirk A1 - Strübbe, Nicole T1 - So wird Bernsteinsäure aus Holzreststoffen gewonnen JF - Plastverarbeiter N2 - Die effiziente Umwandlung von lignocellulosehaltiger Biomasse wie Restholz ist eine wissenschaftliche sowie technologische Herausforderung weltweit. Die Technische Hochschule Rosenheim entwickelt gemeinsam mit Partnern ein neues Verfahren zur Herstellung von Bernsteinsäure aus Holzreststoffen. KW - Bernsteinsäure KW - Reaktive Extrusion Y1 - 2023 VL - 2023 IS - 04 SP - 22 EP - 25 PB - Hüthig GmbH CY - Heidelberg ER - TY - JOUR A1 - Ziegler, Felix A1 - Spindler, Uli T1 - An ammonia refrigerator with an absorption circuit as economizer JF - International Journal of Refrigeration KW - Refrigeration KW - absorption circuit Y1 - 1993 IS - 7/93 SP - 230 EP - 239 ER - TY - JOUR A1 - Zillmer, M. A1 - Karlinger, Peter A1 - Zentgraf, Peter A1 - Würtele, M. A1 - Grimm, G. A1 - Wolf, W. T1 - Vorausschauende Zylindertemperierung BT - Modellprädiktive Regelung verkürzt den Aufheizvorgang und erhöht die Energieeffizienz JF - Kunststoffe KW - Modellprädikative Regelung KW - Aufheizvorgang Y1 - 2016 IS - 10/2016 ER - TY - BOOK A1 - Zimmermann, J. A1 - Beneken, Gerd T1 - Verteilte Komponenten und Datenbankanbindung . Mehrstufige Architekturen mit SQLJ und Enterprise JavaBeansTM 2.0 (Allgemein: Datenbanken) N2 - Mehrstufige Architekturen mit SQLJ und Enterprise JavaBeans Datenbankanbindung und Erstellung von Komponenten sind ein essentieller Bestandteil von Java-Anwendungen. Bei Java-Schnittstellen rückt der neue ANSI-Standard SQLJ für relationale und objektrelationale Datenbanken immer mehr in den Blickpunkt. Bei mehrstufigen Architekturen ist darüber hinaus die Komponentenbildung unabdingbar, und dabei entwickelt sich EJB zu einem De-facto-Standard. Nach einer grundlegenden Einführung geht es im zweiten Teil des Buches um Java-Schnittstellen zu Datenbanken: JDBC, ODMG und SQLJ8. Wie EJB-Komponenten erstellt werden und auf Java-Datenbanken zugreifen, wird im dritten Teil beschrieben. KW - Enterprise JavaBeansTM 2.0 KW - Datenbanken KW - SQLJ Architekturen Y1 - 2000 PB - Addison-Wesley CY - München ER - TY - CHAP A1 - Zinßer, T. A1 - Schmidt, Jochen A1 - Niemann, H. T1 - Performance Analysis of Nearest Neighbor Algorithms for ICP Registration of 3-D Point Sets T2 - Vision, Modeling, and Visualization 2003 N2 - There are many nearest neighbor algorithms tailor made for ICP,but most of them require Special input data like range Images or triangle meshes. We focus on efficient nearest neighbor algorithms that do not impose this limitation, and thus can also be used with 3-D point sets generated by structure-frommotion techniques. We shortly present the evaluated algorithms and introduce the modifications we made to improve their efficiency. In particular, several enhancements to the well-known k-D tree algorithm are described. The first part of our Performance Analysis consists of Experiments on synthetic point sets, whereas the second part features experiments with the ICP algorithm on real point sets. Both parts are completed by a thorough evaluation of the obtained results. KW - ICP Algorithm KW - 3D Point-Sets Y1 - 2003 ER - TY - CHAP A1 - Zinßer, T. A1 - Schmidt, Jochen A1 - Niemann, H. T1 - A Refined ICP Algorithm for Robust 3-D Correspondence Estimation T2 - Proceedings of the IEEE International Conference on Image Processing, volume 2, pages 695-698, Barcelona, Spain N2 - Robust registration of two 3-D point sets is a common problem in computer vision. The iterative closest point (ICP) algorithm is undoubtedly the most popular algorithm for solving this kind of problem. In this paper, we present the Picky ICP algorithm, which has been created by merging several extensions of the standard ICP algorithm, thus improving its robustness and computation time. Using pure 3-D point sets as input data, we do not consider additional information like point color or neighborhood relations. In addition to the standard ICP algorithm and the Picky ICP algorithm proposed in this paper, a robust algorithm due to Masuda and Yokoya and the RICP algorithm by Trucco et al. are evaluated. We have experimentally determined the basin of convergence, robustness to noise and outliers, and computation time of these four ICP based algorithms KW - Iterative closest point algorithm KW - Iterative algorithms KW - Noise robustnes KW - Computer vision Y1 - 2003 ER - TY - CHAP A1 - Zinßler, T. A1 - Schmidt, Jochen A1 - Niemann, H. T1 - Point Set Registration with Integrated Scale Estimation T2 - Proceedings of the Eighth International Conference on Pattern Recognition and Image Processing (PRIP 2005), pages 116-119, Minsk, Republic of Belarus N2 - Wepresentaniterativeregistrationalgorithmfor aligning two differently scaled 3-D point sets. It extends the popular Iterative Closest Point (ICP) algorithm by estimating a scale factor between the two point sets in every iteration. The presented algorithm is especially useful for the registration of point sets generated by structure-frommotion algorithms, which only reconstruct the 3-D structure of a scene upto scale. LiketheoriginalICPalgorithm,thepresentedalgorithm requires a rough pre-alignment of the point sets. In order to determine the necessary accuracy of the pre-alignment, wehaveexperimentallyevaluatedthebasinofconvergence of the algorithm with respect to the initial rotation, translation, andscale factor between the two point sets. KW - Iterative Closest Point KW - Scale Estimation Y1 - 2005 ER - TY - JOUR A1 - Zobel, M. A1 - Denzler, J. A1 - Heigl, B. A1 - Nöth, E. A1 - Paulus, D. A1 - Schmidt, Jochen A1 - Stemmer, G. T1 - MOBSY: Integration of vision and dialogue in service robots JF - Machine Vision and Applications N2 - This contribution introduces MOBSY, a fully integrated, autonomous mobile service robot system. It acts as an automatic dialogue-based receptionist for visitors to our institute. MOBSY incorporates many techniques from different research areas into one working stand-alone system. The techniques involved range from computer vision over speech understanding to classical robotics. Along with the two main aspects of vision and speech, we also focus on the integration aspect, both on the methodological and on the technical level. We describe the task and the techniques involved. Finally, we discuss the experiences that we gained with MOBSY during a live performance at our institute. KW - Service robots KW - Computer vision KW - Speech understanding and dialogue KW - Integrated System Y1 - 2003 ER - TY - JOUR A1 - Zobel, M. A1 - Denzler, J. A1 - Heigl, B. A1 - Nöth, E. A1 - Paulus, D. A1 - Schmidt, Jochen A1 - Stemmer, G. T1 - Demonstration von Bildverarbeitung und Sprachverstehen in der Dienstleistungsrobotik JF - Autonome Mobile Systeme N2 - Die typischerweise gewünschten Einsatzgebiete für Dienstleistungsroboter, z. B. Krankenhäuser oder Seniorenheime, stellen sehr hohe Anforderungen an die Mensch-Maschine-Schnittstelle. Diese Erfordernisse gehen im Allgemeinen über die Möglichkeiten der Standardsensoren, wie Ultraschalloder Infrarotsensoren, hinaus. Es müssen daher ergänzende Verfahren zum Einsatz kommen. Aus der Sicht der Mustererkennung sind die Nutzung des Rechnersehens und des natürlichsprachlichen Dialogs von besonderem Interesse. Dieser Beitrag stellt das mobile System MOBS Y vor. MOBS Y ist ein vollkommen integrierter autonomer mobiler Dienstleistungsroboter. Er dient als ein automatischer dialogbasierter Empfangsservice für Besucher unseres Instituts. MOBSY vereinigt vielfältige Methoden aus unterschiedlichsten Forschungsgebieten in einem eigenständigen System. Die zum Einsatz kommenden Methoden aus dem Bereich der Bildverarbeitung reichen dabei von Objektklassifikation über visuelle Selbstlokalisierung und Rekalibrierung bis hin zu multiokularer Objektverfolgung. Die Dialogkomponente umfasst Methoden der Spracherkennung, des Sprachverstehens und die Generierung von Antworten. Im Beitrag werden die zu erfüllende Aufgabe und die einzelnen Verfahren dargestellt. KW - Dienstleistungsroboter KW - multiokulare Objektverfolgung KW - Spracherkennung KW - Sensorik bei Robotern Y1 - 2001 ER - TY - CHAP A1 - Zobel, M. A1 - Denzler, J. A1 - Heigl, B. A1 - Nöth, E. A1 - Paulus, D. A1 - Schmidt, Jochen A1 - Stemmer, G. T1 - MOBSY: Integration of vision and dialogue in service robots T2 - Computer Vision Systems, Proceedings Second International Workshop, ICVS 2001, Vancouver, Canada N2 - MOBSY is a fully integrated autonomous mobile service robot system. It acts as an automatic dialogue based receptionist for visitors of our institute. MOBSY incorporates many techniques from different research areas into one working stand-alone system. Especially the computer vision and dialogue aspects are of main interest from the pattern recognition’s point of view. To summarize shortly, the involved techniques range from object classification over visual self-localization and recalibration to object tracking with multiple cameras. A dialogue component has to deal with speech recognition, understanding and answer generation. Further techniques needed are navigation, obstacle avoidance, and mechanisms to provide fault tolerant behavior. This contribution introduces our mobile system MOBSY. Among the main aspects vision and speech, we focus also on the integration aspect, both on the methodological and on the technical level. We describe the task and the involved techniques. Finally, we discuss the experiences that we gained with MOBSY during a live performance at the 25th anniversary of our institute KW - Speech recognition KW - Obstacle Avoidance  KW - Humanoid Robot  KW - Service Robot Y1 - 2001 ER - TY - RPRT A1 - Zscheile, Mathias A1 - Auer, Veronika A1 - Gilly, Alexander T1 - BioXfrac: Machbarkeitsstudie zur dezentralen Biomassekonversion durch Kombination innovativer thermo-mechanischer und biochemischer Technologien zur Gewinnung von fermentierbaren Zuckern und BioEnergie. N2 - Ziel des Vorhabens war Prüfung die Untersuchung der technischen und wirtschaftlichen Machbarkeit einer dezentralen Prozesskette zur nachhaltigen Bereitstellung von hochwertigen Grundstoffen aus bislang schwer nutzbarer Non-Food-Biomasse zur stofflichen Nutzung. Die Untersuchung erfolgt mittels der Weiterentwicklung einer mechanischen Aufschluss- und Fraktionierungstechnologie mit anschließender biochemischer Konversion. Insgesamt fanden 14 verschiedene Versuchsläufe innerhalb der Projektlaufzeit statt. In allen Ausgangsmaterialien konnten Zuckerbestandteile mit der enzymatischen Hydrolyse nachgewiesen werden. Somit konnte die technische Machbarkeit bewiesen werden. Nach dem Prinzip einer integrierten Nutzungskaskade wurden die einzelnen Komponenten miteinander verbunden. Die wirtschaftliche Machbarkeit war jedoch nur gegeben, da die Erlöse aus der Biogasanlage die Verluste in der enzymatischen Hydrolyse ausglichen. Die enzymatische Hydrolyse hätte für eine eigene Wirtschaftlichkeit höhere Zuckerausbeuten erzielen müssen. Dies konnte auch unter Verwendung verschiedener zusätzlicher Maßnahmen für keinen der Eingangsstoffe reproduzierbar bewiesen werden. Aus diesem Grund untersucht ein Teil des Konsortiums die wirtschaftliche Machbarkeit einer alternativen Aufschlusstechnologie im Anschluss an das Projekt weiter. KW - Biomassekonversion KW - Fermentation KW - enzymatische Hydrolyse Y1 - 2016 ER - TY - JOUR A1 - Zscheile, Matthias T1 - Holz statt Braunkohle JF - UmweltMagazin N2 - Der BioEconomy Cluster in Halle (Saale) treibt seit 2012 den Strukturwandel in der Wirtschaftsregion Südliches Sachsen-Anhalt voran. Ziel ist, dort und in angrenzenden Gebieten des mitteldeutschen Braunkohlereviers eine holzbasierte Bioökonomie voranzutreiben. KW - Bioökonomie Y1 - 2020 VL - 50 IS - 10-11 SP - 28 EP - 29 PB - VDI Fachmedien GmbH & Co. KG ER - TY - JOUR A1 - Zscheile, Matthias T1 - Holz statt Braunkohle JF - UmweltMagazin KW - Bioökonomie Y1 - 2020 VL - 50 IS - 10-11 ER - TY - CHAP A1 - Zscheile, Matthias A1 - Auer, Veronika A1 - Lang, Tobias A1 - Wojaczek, Adrian A1 - Werndl, Peter T1 - Dimensionserhaltende Altholznutzung – Lösungsansatz auch oder gerade für die Holzverpacker? T2 - VERPACKERTAGE 2023 - Der Zuschnitt im Fokus KW - Altholz KW - Bioökonomie KW - Fertigungstechnik KW - Holztechnik KW - Prozesstechnologie Y1 - 2023 ER -