Mission Analysis For Multiple Rendezvous Of Near-Earth Asteroids Using Earth Gravity Assist,
2010
Air Force Institute of Technology
Mission Analysis For Multiple Rendezvous Of Near-Earth Asteroids Using Earth Gravity Assist, Uriah J. Tobey
Theses and Dissertations
The Jet Propulsion Laboratory (JPL) catalog of near-Earth objects (NEOs) such as asteroids and comets contains over 6600 asteroids and 150 comets as of February of 2010. This includes over 1000 potentially hazardous asteroids, or objects with orbits that pass close enough to Earth to pose a potential impact threat. The asteroid community believes there are a significant number of objects still undiscovered, which makes finding, tracking, and calculating missions to study these objects an active area of research. This study was based on finding orbit solutions using Earth gravity assist to visit one near-Earth object (NEO) a year for …
Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications,
2010
Air Force Institute of Technology
Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications, Jeffrey P. Massman
Theses and Dissertations
The ability to manipulate a complex impedance sheet about a PEC or general dielectric cylinder of arbitrary diameter to control the overall scattering characteristics at particular angles for shielding or scattering applications is presented. It is shown that with the capability to readily control both the real and imaginary components of a percolated lossy film's effective impedance, specific impedance distributions can be obtained to effectively direct the overall nulls in the bistatic scattering pattern. The exact approach only requires negligible truncation error of the matrix solution and can be applied to cylinders of arbitrary size. This approach relies on general …
Global Navigation Satellite System Software Defined Radio,
2010
Air Force Institute of Technology
Global Navigation Satellite System Software Defined Radio, Jason M. Mcginthy
Theses and Dissertations
The GNSS world is quickly growing. The United States’ GPS, the European Union’s Galileo, China’s Compass, and Russia’s GLONASS systems are all developing or modernizing their signals, and there will soon be more navigation satellites in space than ever before. The goal of this research was to develop an initial capability for an AFIT GNSS software receiver. This software receiver is intended to be used for research purposes at the Advanced Navigation Technology (ANT) Center. First a GPS-only software receiver was built. It successfully acquired, tracked, and provided reasonable position estimates. Next, the receiver was successfully modified to acquire and …
Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station,
2010
Air Force Institute of Technology
Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse
Theses and Dissertations
This thesis outlines the design of the electrical components for the space-based ChromoTomography Experiment (CTEx). CTEx is the next step in the development of high-speed chromotomography at the Air Force Institute of Technology. The electrical design of the system is challenging due to the large amount of data that is acquired by the imager and the limited resources that is inherent with space-based systems. Additional complication to the design is the need to know the angle of a spinning prism that is in the field of view very precisely for each image. Without this precise measurement any scene that is …
System Integration And Attitude Control Of A Low-Cost Spacecraft Attitude Dynamics Simulator,
2010
California Polytechnic State University, San Luis Obispo
System Integration And Attitude Control Of A Low-Cost Spacecraft Attitude Dynamics Simulator, Ryan L. Kinnett
Master's Theses
The CalPoly Spacecraft Attitude Dynamics Simulator mimics the rotational dynamics of a spacecraft in orbit and acts as a testbed for spacecraft attitude control system development and demonstration. Prior to this thesis, the simulator platform and several subsystems had been designed and manufactured, but the total simulator system was not yet capable of closed-loop attitude control. Previous attempts to make the system controllable were primarily mired by data transport performance. Rather than exporting data to an external command computer, the strategy implemented in this thesis relies on a compact computer onboard the simulator platform to handle both attitude control processing …
Control Law Design And Validation For A Helicopter In-Flight Simulator,
2010
California Polytechnic State University, San Luis Obispo
Control Law Design And Validation For A Helicopter In-Flight Simulator, Brian T. Fujizawa
Master's Theses
In-flight simulation allows one aircraft to simulate the dynamic response of another aircraft. A control system designed to give RASCAL, a JUH-60A Black Hawk helicopter based at Moffett Field, CA, in-flight simulation capabilities has been designed, optimized and validated in this research. A classical explicit model following control system with a frequency dependent feedback controller was used. The frequency dependent controller allows model following of the attitude in the short term and the velocity in the long term. Controller gains were optimized using a high order, linearized model of UH-60 dynamics. Non-linear simulations of the control laws were performed, first …
Adaptive Control Applied To The Cal Poly Spacecraft Attitude Dynamics Simulator,
2010
California Polytechnic State University, San Luis Obispo
Adaptive Control Applied To The Cal Poly Spacecraft Attitude Dynamics Simulator, Matthew C. Downs
Master's Theses
The goal of this thesis is to use the Cal Poly Spacecraft Attitude Dynamics Simulator to provide proof of concept of two adaptive control theories developed by former Cal Poly students: Nonlinear Direct Model Reference Adaptive Control and Adaptive Output Feedback Control. The Spacecraft Attitude Dynamics Simulator is a student-built air bearing spacecraft simulator controlled by four reaction wheels in a pyramidal arrangement. Tests were performed to determine the effectiveness of the two adaptive control theories under nominal operating conditions, a “plug-and-play” spacecraft scenario, and under simulated actuator damage. Proof of concept of the adaptive control theories applied to attitude …
Adaptive Pid Control Based On Rbf Network Approximating The Satellite Clock Thermal Model,
2010
Nanyang Technological University, Singapore
Adaptive Pid Control Based On Rbf Network Approximating The Satellite Clock Thermal Model, Bin Xu
Bin Xu
The accuracy o f t ime information prov ided by sate llite clock g reat ly depends on its frequency stab ili ty, w hich is up to the stability o f the co re tempera ture. Th is paper introduces an adaptive PID control for the sate llite c lock system whose mode l is approx imated based on RBF neural netw orks. Simu lation resu lts demonstrate the va lid ity o f the proposed contro.l
Designing For The Future: A Cognitive-Adaptive-Man-Machine-Interface,
2010
Iowa State University
Designing For The Future: A Cognitive-Adaptive-Man-Machine-Interface, Claudia Keinrath, Michael C. Dorneich, Jiri Vasek
Michael C. Dorneich
The forecasts of the International Civil Aviation Organization envisage a growth in world air travel of 5% per annum until 2020. The air traffic in Europe is therefore expected to more than double by 2020. In order to deal with the growth, the European Air Traffic Management (ATM) system will undergo major changes. The envisaged next generation ATM will require new technologies to meet future collaborative decision making, self separation, precision 4D path following, and closer aircraft spacing. The CAMMI (Cognitive Adaptive Man Machine Interface) program addresses human factors priorities in various domains by developing concepts that balance operator workload, …
Efficient Tether Dynamic Model Formulation Using Recursive Rigid-Body Dynamics,
2010
University of Alabama - Huntsville
Efficient Tether Dynamic Model Formulation Using Recursive Rigid-Body Dynamics, Brad Hembree, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
A computationally efficient discrete model for low-strain tethers used in many engineering applications is developed without the use of elastic elements. The tether is modelled using N links, with each link treated as a body of revolution where it is assumed the tether spin is negligible to the dynamics, resulting in each link having only two degrees of freedom. A recursive algorithm is developed for the dynamic equations, with the solution procedure being an order N method requiring only a 2 x 2 matrix inversion, resulting in approximately half the computations of the general recursive algorithm. A comparison between the …
Effects Of Canopy-Payload Relative Motion On Control Of Autonomous Parafoils,
2010
George Fox University
Effects Of Canopy-Payload Relative Motion On Control Of Autonomous Parafoils, Nathan Slegers
Faculty Publications - Biomedical, Mechanical, and Civil Engineering
An 8 degree-of-freedom model is developed that accurately models relative pitching and yawing motion of a payload with respect to a parafoil. Constraint forces and moments are found analytically rather than using artificial constraint stabilization. A turn rate controller common in precision placement algorithms is used to demonstrate that relative yawing motion of the payload can result in persistent oscillations of the system. A model neglecting relative payload yawing failed to predict the same oscillations. It is shown that persistent oscillations can be eliminated by reduction of feedback gains; however, resulting tracking performance is poor. A reduced order linear model …
Fusion Of Imprecise Qualitative Information,
2010
University of New Mexico
Fusion Of Imprecise Qualitative Information, Florentin Smarandache, Xinde Li, Xianzhong Dai, Jean Dezert
Branch Mathematics and Statistics Faculty and Staff Publications
In this paper, we present a new 2-tuple linguistic representation model, i.e. Distribution Function Model (DFM), for combining imprecise qualitative information using fusion rules drawn from Dezert-Smarandache Theory (DSmT) framework. Such new approach allows to preserve the precision and efficiency of the combination of linguistic information in the case of either equidistant or unbalanced label model. Some basic operators on imprecise 2-tuple labels are presented together with their extensions for imprecise 2-tuple labels. We also give simple examples to show how precise and imprecise qualitative information can be combined for reasoning under uncertainty. It is concluded that DSmT can deal …
