381 research outputs found

    Control of a launcher in atmospheric ascent with guardian maps

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    This paper describes the synthesis of a SISO scheduled controller for a launcher vehicle. The problem consists in designing a control law which will be valid on the atmospheric ascent trajectory from time 25 s to time 60 s, while ensuring robustness and performance requirements. Moreover a flexible model with two bending modes is considered, making the problem more challenging. An algorithm based upon guardian maps has been retained in order to find an a priori fixed architecture controller. The algorithm yields a sequence of controllers that ensures that pole confinement constraints are fulfilled for any time between 25 s and 60 s. The user can then interpolate those controllers to find a scheduled controller with respect to time

    Wings in Orbit: Scientific and Engineering Legacies of the Space Shuttle, 1971-2010

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    The Space Shuttle is an engineering marvel perhaps only exceeded by the station itself. The shuttle was based on the technology of the 1960s and early 1970s. It had to overcome significant challenges to make it reusable. Perhaps the greatest challenges were the main engines and the Thermal Protection System. The program has seen terrible tragedy in its 3 decades of operation, yet it has also seen marvelous success. One of the most notable successes is the Hubble Space Telescope, a program that would have been a failure without the shuttle's capability to rendezvous, capture, repair, as well as upgrade. Now Hubble is a shining example of success admired by people around the world. As the program comes to a close, it is important to capture the legacy of the shuttle for future generations. That is what "Wings In Orbit" does for space fans, students, engineers, and scientists. This book, written by the men and women who made the program possible, will serve as an excellent reference for building future space vehicles. We are proud to have played a small part in making it happen. Our journey to document the scientific and engineering accomplishments of this magnificent winged vehicle began with an audacious proposal: to capture the passion of those who devoted their energies to its success while answering the question "What are the most significant accomplishments?" of the longestoperating human spaceflight program in our nation s history. This is intended to be an honest, accurate, and easily understandable account of the research and innovation accomplished during the era

    Issues in Modeling Military Space

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    Fighter Pilots students undertake an intense 120-day training program. New classes of students enter the training program at regular interval. Students endured rigorous academic, simulator, and aircraft training throughout the program. Squadron schedulers ensure the multiple classes and students are scheduled for the activities. Simulator and aircraft training are scheduled individual for each student. Academic training are taught to the class. Aircraft utilization must also be considered. Aircraft Sortie training are also constrained by daylight hours. Additionally, students are limited to a maximum of three training events in a given day. Squadron schedulers must balance these requirements to ensure students meet their training requirements and successfully graduate. The dynamic training environment requires advanced robust schedules with flexibility to accommodate changes. A Visual Interactive Modeling approach is used to generate schedules. Current schedules are being generated manually with an Excel spreadsheet. Taking advantage of Excel\u27s Visual Basic Programming language, the Excel tool is modified in several ways. Scheduling Dispatch rules are implemented to automatically generate feasible schedules. Graphical User Interfaces are used to create a user-friendly environment. Schedulers guide the schedule building process to produce a robust schedule. An attrition environment is created to simulate attrition probabilities of aircraft sortie training due to operations, maintenance, weather, and other cancellations. Analysis of dispatch rules are analyzed

    Proceedings of the Seventh Annual Summer Conference. NASA/USRA: University Advanced Design Program

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    The Advanced Design Program (ADP) is a unique program that brings together students and faculty from U.S. engineering schools with engineers from the NASA centers through integration of current and future NASA space and aeronautics projects into university engineering design curriculum. The Advanced Space Design Program study topics cover a broad range of projects that could be undertaken during a 20-30 year period beginning with the deployment of the Space Station Freedom. The Advanced Aeronautics Design Program study topics typically focus on nearer-term projects of interest to NASA, covering from small, slow-speed vehicles through large, supersonic passenger transports and on through hypersonic research vehicles. Student work accomplished during the 1990-91 academic year and reported at the 7th Annual Summer Conference is presented

    DRONE DELIVERY OF CBNRECy – DEW WEAPONS Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD)

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    Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD) is our sixth textbook in a series covering the world of UASs and UUVs. Our textbook takes on a whole new purview for UAS / CUAS/ UUV (drones) – how they can be used to deploy Weapons of Mass Destruction and Deception against CBRNE and civilian targets of opportunity. We are concerned with the future use of these inexpensive devices and their availability to maleficent actors. Our work suggests that UASs in air and underwater UUVs will be the future of military and civilian terrorist operations. UAS / UUVs can deliver a huge punch for a low investment and minimize human casualties.https://newprairiepress.org/ebooks/1046/thumbnail.jp

    Cyber-Human Systems, Space Technologies, and Threats

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    CYBER-HUMAN SYSTEMS, SPACE TECHNOLOGIES, AND THREATS is our eighth textbook in a series covering the world of UASs / CUAS/ UUVs / SPACE. Other textbooks in our series are Space Systems Emerging Technologies and Operations; Drone Delivery of CBNRECy – DEW Weapons: Emerging Threats of Mini-Weapons of Mass Destruction and Disruption (WMDD); Disruptive Technologies with applications in Airline, Marine, Defense Industries; Unmanned Vehicle Systems & Operations On Air, Sea, Land; Counter Unmanned Aircraft Systems Technologies and Operations; Unmanned Aircraft Systems in the Cyber Domain: Protecting USA’s Advanced Air Assets, 2nd edition; and Unmanned Aircraft Systems (UAS) in the Cyber Domain Protecting USA’s Advanced Air Assets, 1st edition. Our previous seven titles have received considerable global recognition in the field. (Nichols & Carter, 2022) (Nichols, et al., 2021) (Nichols R. K., et al., 2020) (Nichols R. , et al., 2020) (Nichols R. , et al., 2019) (Nichols R. K., 2018) (Nichols R. K., et al., 2022)https://newprairiepress.org/ebooks/1052/thumbnail.jp

    Air Force Institute of Technology Research Report 2018

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    This Research Report presents the FY18 research statistics and contributions of the Graduate School of Engineering and Management (EN) at AFIT. AFIT research interests and faculty expertise cover a broad spectrum of technical areas related to USAF needs, as reflected by the range of topics addressed in the faculty and student publications listed in this report. In most cases, the research work reported herein is directly sponsored by one or more USAF or DOD agencies. AFIT welcomes the opportunity to conduct research on additional topics of interest to the USAF, DOD, and other federal organizations when adequate manpower and financial resources are available and/or provided by a sponsor. In addition, AFIT provides research collaboration and technology transfer benefits to the public through Cooperative Research and Development Agreements (CRADAs). Interested individuals may discuss ideas for new research collaborations, potential CRADAs, or research proposals with individual faculty using the contact information in this document

    Contrôle d'attitude d'un lanceur en phase atmosphérique approche par applications gardiennes

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    RÉSUMÉ: Dans un premier temps, la modélisation d’un lanceur spatial met en avant l’importance des variations des paramètres au cours de l’ascension. Ils sont en effet fortement dépendants de la variation de la masse avec la consommation des ergols. Le modèle utilisé prend ainsi en compte cette évolution en linéarisant les équations autour de 6 points de vol principaux, pour obtenir des modèles linéaires invariants dans le temps. Chacun de ces modèles devra être stabilisé par une unique loi de commande, tout en respectant les performances désirées. La considération des modes de flexion du lanceur rend alors la synthèse plus complexe. Une autre conséquence de l’évolution temporelle est le séquencement des gains des contrˆo- leurs obtenus. Il est en effet montré dans le mémoire qu’aucun réglage constant du correcteur adopté ne permet de respecter le cahier des charges sur toute la trajectoire. Ensuite, la complexité de modélisation du lanceur complet amène à considérer les erreurs et les incertitudes de modèle. Elles sont là encore un enjeu majeur du projet puisqu’il faut pouvoir assurer les performances nominales précédentes de façon robuste. Les applications gardiennes, de par leur propriétés, se sont révélées les plus adaptées pour traiter un tel pro- blème de séquencement avec respect de performances robustes. Dans cette optique, un aspect essentiel de la Maîtrise porte sur le développement de méthodes de synthèse basées sur les applications gardiennes. Il est en effet apparu que les quelques travaux portant sur ce sujet développaient essentiellement la théorie, et que la mise en œuvre de ces méthodes pouvait être améliorée. Deux approches sont ainsi développées à travers le projet. La première s’appuie sur une vi- sualisation graphique des lieux d’annulation des applications gardiennes. Un programme basé sur l’analyse d’image permet de vérifier automatiquement les réglages des gains qui satisfont les contraintes. La seconde méthode s’appuie sur une optimisation portant sur les applications gardiennes dans des zones d’intérêt. Par itérations successives, il est alors possible de partir du système en boucle ouverte pour aboutir à un réglage des gains acceptable en boucle fermée. Les méthodes élaborées ont été testées et éprouvées sur le cas du lanceur, avec le cahier des charges fourni par ASTRIUM-ST. Cette application pratique a été motivée par la complexité du système, les contraintes variées à considérer et l’importance de la robustesse pour ce type de commande. Autant de contraintes qui ont permis de valider l’intérêt et l’efficacité des applications gardiennes sur ce type de problème.---------- ABSTRACT: In a first phase, the modelling process underlines the presence of highly time varying parameters during the ascent, due to a fast mass variation along with propellant consumption. Linearizing the dynamical equations at six main flight instants yields linear time invariant models to be considered during control design. Each of them is to be stabilized by one control law, while respecting given specifications. The synthesis becomes even more complex when the bending modes are taken into account. Moreover, scheduling appears necessary to deal with the time variations. Indeed it is shown that no single gain setting is able to respect all the specifications along the trajectory. Furthermore, increasing complexity when modelling a whole launch vehicle pushes one to consider the model’s errors and uncertainties. They represent a major issue in this study since it is asked to ensure the nominal performances in a robust fashion. Owing to their properties, guardian maps appear to be the most suitable tool to deal with such a problem of scheduling with robust performances. In light of this, the development of synthesis methods based on guardian maps is the main contribution of the project. It appears that actual state of the art in this field is focused on theoretical issues, whereas practical ones could be improved. Two approches are presented in the memoire. The first one is based on a graphical ap- proach consisting in drawing the vanishing locus of guardian maps. A program using image analysis techniques is devised to check automatically which gain settings satisfy the con- straints. The second one is based on an optimisation procedure involving guardian maps. Starting with the open loop system, the iterative process proposed ends up with a satisfactory gain setting for the closed-loop. These methods are tried and tested for the launch vehicle, with specifications from ASTRIUM-ST. Their practical application is motivated by the system complexity, the differ- ent kinds of constraints and the essential need for robustness. Many restrictions that finally bring about the interest and the efficiency of guardian maps for such a problem

    Moon Missions:The Way Ahead (NIAS/CSS/ISSSP/U/RR/10/2023)

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    The lunar missions gained impetus in the 21st century after decades of lull. The newer sprite in lunar missions began with orbiter and impact missions, which included India’s moon -impact probe onboard the Chandrayaan 1, in 2008. Subsequent robotic missions included orbiters, landers and rovers as well as sample collection missions. The Lunar south polar regions which is under permanent shadow is expected to have reserves of water-ice, essential for lunar habitation and as a source for future deep space missions(space) operating from lunar surface. Other Lunar resources include helium 3 a potential source for nuclear fusion reactors and other minerals which can be commercially exploited and in-situ resource utilization. Consequently, number of countries, space agencies and private parties are keen on lunar exploration. This report details the lunar explorations carried out and being planned, the initiatives taken by leading space faring countries and the technological aspects of lunar exploration. The role of international cooperation is emphasized
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