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Articles 1 - 30 of 39
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Radar Based Navigation In Unknown Terrain, Kyle J. Kauffman
Radar Based Navigation In Unknown Terrain, Kyle J. Kauffman
Theses and Dissertations
There is a great need to develop non-GPS based methods for positioning and navigation in situations where GPS is not available. This research focuses on the development of an Ultra-Wideband Orthogonal Frequency Division Multiplexed (UWB-OFDM) radar as a navigation sensor in GPS-denied environments. A side-looking vehicle-fixed UWB-OFDM radar is mounted to a ground or aerial vehicle continuously collecting data. A set of signal processing algorithms and methods are developed which use the raw radar data to aide in calculating the vehicle position and velocity via a simultaneous localization and mapping (SLAM) approach. The radar processing algorithms detect strong, persistent, and …
Modeling The Effects Of The Local Environment On A Received Gnss Signal, Marshall E. Haker
Modeling The Effects Of The Local Environment On A Received Gnss Signal, Marshall E. Haker
Theses and Dissertations
There is an ongoing need in the GNSS community for the development of high-fidelity simulators which generate data that replicates what can truly be expected from a challenging environment such as an urban canyon or an indoor environment. The algorithm developed for use in the research in this dissertation, the Signal Decomposition and Parameterization Algorithm (SDPA), is presented in order to respond to this need. This algorithm is designed to decompose a signal received using a GNSS recording and playback system and output parameters that can be used to reconstruct the effects on the signal of the environment local to …
Operationally Responsive Spacecraft Using Electric Propulsion, Thomas C. Co
Operationally Responsive Spacecraft Using Electric Propulsion, Thomas C. Co
Theses and Dissertations
A desirable space asset is responsive and flexible to mission requirements, low-cost, and easy to acquire. Highly-efficient electric thrusters have been considered a viable technology to provide these characteristics; however, it has been plagued by limitations and challenges such that operational implementation has been severely limited. The technology is constantly improving, but even with current electric propulsion, a spacecraft is capable of maneuvering consistently and repeatedly in low-Earth orbit to provide a responsive and flexible system. This research develops the necessary algorithm and tools to demonstrate that EP systems can maneuver significantly in a timely fashion to overfly any target …
Intelligent Behavioral Action Aiding For Improved Autonomous Image Navigation, Kwee Guan Eng
Intelligent Behavioral Action Aiding For Improved Autonomous Image Navigation, Kwee Guan Eng
Theses and Dissertations
In egomotion image navigation, errors are common especially when traversing areas with few landmarks. Since image navigation is often used as a passive navigation technique in Global Positioning System (GPS) denied environments; egomotion accuracy is important for precise navigation in these challenging environments. One of the causes of egomotion errors is inaccurate landmark distance measurements, e.g., sensor noise. This research determines a landmark location egomotion error model that quantifies the effects of landmark locations on egomotion value uncertainty and errors. The error model accounts for increases in landmark uncertainty due to landmark distance and image centrality. A robot then uses …
Ground Vehicle Navigation Using Magnetic Field Variation, Jeremiah A. Shockley
Ground Vehicle Navigation Using Magnetic Field Variation, Jeremiah A. Shockley
Theses and Dissertations
The Earth's magnetic field has been the bedrock of navigation for centuries. The latest research highlights the uniqueness of magnetic field measurements based on position due to large scale variations as well as localized perturbations. These observable changes in the Earth's magnetic field as a function of position provide distinct information which can be used for navigation. This dissertation describes ground vehicle navigation exploiting variation in Earth's magnetic field using a self-contained navigation system consisting of only a magnetometer and magnetic field maps. In order to achieve navigation, effective calibration enables repeatable magnetic field measurements from different vehicles and facilitates …
Passive Synthetic Aperture Radar Imaging Using Commercial Ofdm Communication Networks, Jose R. Gutierrez Del Arroyo
Passive Synthetic Aperture Radar Imaging Using Commercial Ofdm Communication Networks, Jose R. Gutierrez Del Arroyo
Theses and Dissertations
Modern communication systems provide myriad opportunities for passive radar applications. OFDM is a popular waveform used widely in wireless communication networks today. Understanding the structure of these networks becomes critical in future passive radar systems design and concept development. This research develops collection and signal processing models to produce passive SAR ground images using OFDM communication networks. The OFDM-based WiMAX network is selected as a relevant example and is evaluated as a viable source for radar ground imaging. The monostatic and bistatic phase history models for OFDM are derived and validated with experimental single dimensional data. An airborne passive collection …
Adaptive Routing Algorithm For Priority Flows In A Network, Timothy J. Carbino
Adaptive Routing Algorithm For Priority Flows In A Network, Timothy J. Carbino
Theses and Dissertations
This research presents the development of an Adaptive Routing Algorithm for Priority (ARAP) flows in a Network. Devices in today's battle space require information to function. Additional bandwidth requirements for such devices place an increased burden on the already congested networks in the battle space. Some devices require real time information (high priority) and other devices will not require real time information (low priority). Existing protocols treat the network like an opaque entity and have little knowledge of user requirements. User requirement information is available in tactical networks and we can take advantage of the known requirements to better optimize …
Decentralized Riemannian Particle Filtering With Applications To Multi-Agent Localization, Martin J. Eilders
Decentralized Riemannian Particle Filtering With Applications To Multi-Agent Localization, Martin J. Eilders
Theses and Dissertations
The primary focus of this research is to develop consistent nonlinear decentralized particle filtering approaches to the problem of multiple agent localization. A key aspect in our development is the use of Riemannian geometry to exploit the inherently non-Euclidean characteristics that are typical when considering multiple agent localization scenarios. A decentralized formulation is considered due to the practical advantages it provides over centralized fusion architectures. Inspiration is taken from the relatively new field of information geometry and the more established research field of computer vision. Differential geometric tools such as manifolds, geodesics, tangent spaces, exponential, and logarithmic mappings are used …
Enhancing Trust In The Smart Grid By Applying A Modified Exponentially Weighted Averages Algorithm, Andrew T. Kasperek
Enhancing Trust In The Smart Grid By Applying A Modified Exponentially Weighted Averages Algorithm, Andrew T. Kasperek
Theses and Dissertations
The main contribution of this thesis is the development and application of a modified Exponentially Weighted Moving Algorithm (EWMA) algorithm, and its ability to robustly function in the face varying numbers of bad (malicious or malfunctioning) Special Protection System (SPS) nodes. Simulation results support the use of the proposed modified EWMA reputation based trust module in SPSs within a smart grid environment. This modification results in the ability to easily maintain the system above the minimum acceptable frequency of 58.8 Hz at the 95% confidence interval, when challenged with test cases containing 5, 10 and 15 bad node test cases …
Cross Hallway Detection And Indoor Localization Using Flash Laser Detection And Ranging, Istvan M. Prileszky
Cross Hallway Detection And Indoor Localization Using Flash Laser Detection And Ranging, Istvan M. Prileszky
Theses and Dissertations
A flash LADAR is investigated as a source of navigation information to support cross-hallway detection and relative localization. To accomplish this, a dynamic, flexible simulation was developed that simulated the LADAR and the noise of a LADAR system. Using simulated LADAR data, algorithms were developed that were shown to be effective at detecting cross hallways in simulated ideal environments and in simulated environments with noise. Relative position was determined in the same situations. A SwissRanger SR4000 flash LADAR was then used to collect real data and to verify algorithm performance in real environments. Hallway detection was shown to be possible …
An Application Of Con-Resistant Trust To Improve The Reliability Of Special Protection Systems Within The Smart Grid, Crystal M. Shipman
An Application Of Con-Resistant Trust To Improve The Reliability Of Special Protection Systems Within The Smart Grid, Crystal M. Shipman
Theses and Dissertations
This thesis explores an application of a con-resistant trust mechanism to improve the performance of communications-based special protection systems to further enhance their effectiveness and resiliency. New initiatives in the energy sector are paving the way for the emergent communications-based smart grid technology. Smart grids incorporate modern technologies in an effort to be more reliable and efficient. However, with the benefits of this new technology comes added risk. This research utilizes a con-resistant trust mechanism as a method to quickly identify malicious or malfunctioning protection system nodes in order to mitigate the resulting instabilities in the smart grid. The feasibility …
Multi-Observation Continuous Density Hidden Markov Models For Anomaly Detection In Full Motion Video, Matthew P. Ross
Multi-Observation Continuous Density Hidden Markov Models For Anomaly Detection In Full Motion Video, Matthew P. Ross
Theses and Dissertations
An increase in sensors on the battlefield produces an abundance of collected data that overwhelms the processing capability of the DoD. Automated Visual Surveillance (AVS) seeks to use machines to better exploit increased sensor data, such as by highlighting anomalies. In this thesis, we apply AVS to overhead Full Motion Video (FMV). We seek to automate the classification of soldiers in a simulated combat scenario into their agent types. To this end, we use Multi-Dimensional Continuous Density Hidden Markov Models (MOCDHMMs), a form of HMM which models a training dataset more precisely than simple HMMs. MOCDHMMs are theoretically developed but …
Resource Provisioning In Large-Scale Self-Organizing Distributed Systems, M. Brent Reynolds
Resource Provisioning In Large-Scale Self-Organizing Distributed Systems, M. Brent Reynolds
Theses and Dissertations
This dissertation researches the mathematical translation of resource provisioning policy into mathematical terms and parameters to solve the on-line service placement problem. A norm called the Provisioning Norm is introduced. Theorems presented in the work show the Provisioning Norm utility function and greedy, random, local search effectively and efficiently solve the on-line problem. Caching of placements is shown to reduce the cost of change but does not improve response time performance. The use of feedback control theory is shown to be effective at significantly improving performance but increases the cost of change. The theoretical results are verified using a decentralized, …
Integration, Testing And Validation, Of A Small Hybrid-Electric Remotely-Piloted Aircraft, Joseph K. Ausserer
Integration, Testing And Validation, Of A Small Hybrid-Electric Remotely-Piloted Aircraft, Joseph K. Ausserer
Theses and Dissertations
Parallel hybrid-electric technology offers a wide variety of new mission capabilities including low-observable loiter operations and increased fuel efficiency for small remotely-piloted aircraft. This research focused on the integration, validation, and testing of a hybrid-electric propulsion system consisting of commercially available components to fabricate a small remotely-piloted aircraft capable of extended low-observable operation. Three novel aspects contributed to the success of the design: optimization of the propulsive components to the integrated system, torque control of the components for additive power, and a one-way bearing/ pulley mechanism (patent pending) mechanically linking the hybrid system components. To the knowledge of the author …
Development Of A Star Tracker-Based Reference System For Accurate Attitude Determination Of A Simulated Spacecraft, Jorge G. Padro
Development Of A Star Tracker-Based Reference System For Accurate Attitude Determination Of A Simulated Spacecraft, Jorge G. Padro
Theses and Dissertations
The goal of this research effort is to investigate the analysis, design, integration, testing, and validation of a complete star tracker and star field simulator system concept for AFIT's satellite simulator, SimSat. Previous research has shown that while laboratory-based satellite simulators benefit from star trackers, the approach of designing the star field can contribute significant error if the star field is generated on a flat surface. To facilitate a star pattern that better represents a celestial sky, a partially hemispherical dome surface is suspended above SimSat and populated with a system of light emitting diodes of various intensities and angles …
Application Of Multi-Input Multi-Output Feedback Control For F-16 Ventral Fin Buffet Alleviation Using Piezoelectric Actuators, Tomoyuki D. Ono
Application Of Multi-Input Multi-Output Feedback Control For F-16 Ventral Fin Buffet Alleviation Using Piezoelectric Actuators, Tomoyuki D. Ono
Theses and Dissertations
Control of structural vibrations has been a popular topic. Use of MFC piezoelectric actuators and co-located sensors allows for an active rather than passive control method. The F-16 ventral fin is susceptible to buffet induced vibrations and is a perfect test structure for active vibration control for flight-testing. The research follows the previous ACTIVE FIN project and improves on the design by increasing the number of actuator layers, available actuator power, and using multi-input multi-output (MIMO) control algorithms. The research involved experimental identification of the ventral fin and its principle strain directions, selection of system components, determination of mathematical plant …
Context Aware Routing Management Architecture For Airborne Networks, Joan A. Betances
Context Aware Routing Management Architecture For Airborne Networks, Joan A. Betances
Theses and Dissertations
This thesis advocates the use of Kalman filters in conjunction with network topology information derived from the Air Tasking Order (ATO) during the planning phase for military missions. This approach is the basis for an algorithm that implements network controls that optimize network performance for Mobile Ad hoc Networks (MANET). The trajectories of relevant nodes (airborne platforms) participating in the MANET can be forecasted by parsing key information contained in the ATO. This information is used to develop optimum network routes that can significantly improve MANET performance. Improved MANET performance in the battlefield enables decision makers to access information from …
Integration Of Cold Atom Interferometry Ins With Other Sensors, Aaron J. Canciani
Integration Of Cold Atom Interferometry Ins With Other Sensors, Aaron J. Canciani
Theses and Dissertations
Inertial navigation systems (INS) using cold-atom interferometry are currently under development, and sensors in these systems are expected to be several orders of magnitude more ccurate than current navigation grade sensors. This signi cant increase in accuracy motivates the need to explore how these high accuracy inertial navigation systems can be integrated with other sensors. This research focuses on methods of integrating cold atom interferometry INS with conventional navigation grade INS, as well as with GPS. Results from a full 6 degree of freedom simulation show that integrating CAI INS with navigation grade INS is a successful way to address …
Cooperative Localization On Computationally Constrained Devices, Randy S. Cicale Ii
Cooperative Localization On Computationally Constrained Devices, Randy S. Cicale Ii
Theses and Dissertations
Cooperative localization is a useful way for nodes within a network to share location information in order to better arrive at a position estimate. This is handy in GPS contested environments (indoors and urban settings). Most systems exploring cooperative localization rely on special hardware, or extra devices to store the database or do the computations. Research also deals with specific localization techniques such as using Wi-Fi, ultra-wideband signals, or accelerometers independently opposed to fusing multiple sources together. This research brings cooperative localization to the smartphone platform, to take advantage of the multiple sensors that are available. The system is run …
Automated Aerial Refueling Position Estimation Using A Scanning Lidar, Joseph A. Curro Ii
Automated Aerial Refueling Position Estimation Using A Scanning Lidar, Joseph A. Curro Ii
Theses and Dissertations
This research examines the application of using a scanning Light Detection and Ranging(LiDAR) to perform Automated Aerial Refueling(AAR). Specifically this thesis presents two algorithms to determine the relative position between the tanker and receiver aircraft. These two algorithms require a model of the tanker aircraft and the relative attitude between the aircraft. The first algorithm fits the measurements to the model of the aircraft using a modified Iterative Closest Point (ICP) algorithm. The second algorithm uses the model to predict LiDAR scans and compare them to actual measurements while perturbing the estimated location of the tanker. Each algorithm was tested …
Universal Plug-N-Play Sensor Integration For Advanced Navigation, Daniel L. Elsner
Universal Plug-N-Play Sensor Integration For Advanced Navigation, Daniel L. Elsner
Theses and Dissertations
This research investigates the potential for Plug-n-Play sensor integration for navigation and other applications. Specifically, the requirements of such a system are outlined and attempts are made to achieve them using two separate systems: one using Robot Operating System (ROS) as middleware and the other using more traditional software design patterns. The end result is not so much a deliverable in terms of software, but more of a feasibility analysis comparing the two approaches.
Modeling, Simulation, And Flight Test For Automatic Flight Control Of The Condor Hybrid-Electric Remote Piloted Aircraft, Christopher Giacomo
Modeling, Simulation, And Flight Test For Automatic Flight Control Of The Condor Hybrid-Electric Remote Piloted Aircraft, Christopher Giacomo
Theses and Dissertations
This thesis describes the modeling and verification process for the stability and control analysis of the Condor hybrid-electric Remote-Piloted Aircraft (HE-RPA). Due to the high-aspect ratio, sailplane-like geometry of the aircraft, both longitudinal and lateral/directional aerodynamic moments and effects are investigated. The aircraft is modeled using both digital DATCOM as well as the JET5 Excel-based design tool. Static model data is used to create a detailed assessment of predictive flight characteristics and PID autopilot gains that are verified with autonomous flight test. PID gain values were determined using a six degree of freedom linear simulation with the Matlab/SIMULINK software. Flight …
Air-To-Air Missile Enhanced Scoring With Kalman Smoothing, Jonathon S. Gipson
Air-To-Air Missile Enhanced Scoring With Kalman Smoothing, Jonathon S. Gipson
Theses and Dissertations
A correct estimate of a missile's flight path is essential to USAF test and evaluation efforts. The USAF air-to-air Weapons System Evaluation Program (WSEP) targets unmanned aerial drones in hundreds of live-fire missile tests each year. The current QF-4 drone inventory is expected to be depleted by 2015. The QF-16 Full Scale Aerial Target (FSAT) contract has been awarded to convert usable early model F-16s into remote-controlled drones. The QF-16 will provide a highly-maneuverable, realistic testing environment for 5th generation fighters. To accomplish their mission, WSEP requires a scoring system capable of estimating the trajectory of a missile relative to …
The Effects Of Cognitive Jamming On Wireless Sensor Networks Used For Geolocation, Michael A. Huffman
The Effects Of Cognitive Jamming On Wireless Sensor Networks Used For Geolocation, Michael A. Huffman
Theses and Dissertations
The increased use of Wireless Sensor Networks (WSN) for geolocation has led to an increased reliance on this technology. Jamming, protecting jamming, and detecting jamming in a WSN are areas of study that have greatly increased in interest. This research uses simulations and data collected from hardware experiments to test the effects of jamming on a WSN. Hardware jamming was tested using a Universal Software Radio Peripheral (USRP) Version 2 to assess the effects of jamming on a cooperative network of Java Sun SPOTs. The research combines simulations and data collected from the hardware experiments to see the effects of …
Augmenting The Global Positioning System With Foreign Navigation Systems And Alternative Sensors, Christopher B. Killion
Augmenting The Global Positioning System With Foreign Navigation Systems And Alternative Sensors, Christopher B. Killion
Theses and Dissertations
The United States Global Positioning System (GPS), with its great accuracy, receives extensive use by civilians and military organizations throughout the world. However, in areas with limited or partially obstructed views of the sky, such as amongst tall buildings or imposing geographic features, a position solution can be difficult or impossible to obtain as the limited view of the sky decreases the number of visible satellites. Augmenting the GPS constellation by receiving signals from foreign satellite navigation systems as well as using measurements from inertial and barometric sensors can increase the availability of a position solution in a degraded reception …
Uhf Antenna Design For Afit Random Noise Radar, Matthew T. Ludwig
Uhf Antenna Design For Afit Random Noise Radar, Matthew T. Ludwig
Theses and Dissertations
The design of a small ultra-high frequency (UHF) antenna for an ultra-wideband (UWB) random noise radar (RNR) system was undertaken to improve system bandwidth and reduce overall system size. The Vivaldi dipole antenna class showed the greatest potential for high performance in this specific application. After extensive computer simulation, three designs were built using two printed circuit board antenna construction methods. The antipodal chopped Vivaldi dipole antenna, built with a milling machine, achieved a wider bandwidth and more uniform spectral performance characteristics. Though current results show improvement over the current log-periodic antenna (LPA) used on the system, greater performance could …
Covariance Analysis Of Vision Aided Navigation By Bootstrapping, Andrew L. Relyea
Covariance Analysis Of Vision Aided Navigation By Bootstrapping, Andrew L. Relyea
Theses and Dissertations
Inertial Navigation System (INS) aiding using bearing measurements taken over time of stationary ground features is investigated. A cross country flight, in two and three dimensional space, is considered, as well as a vertical drop in three dimensional space. The objective is to quantify the temporal development of the uncertainty in the navigation states of an aircraft INS which is aided by taking bearing measurements of ground objects which have been geolocated using ownship position. It is shown that during wings level flight at constant speed and a fixed altitude, an aircraft that tracks ground objects and over time sequentially …
Passive Multistatic Radar Imaging Using An Ofdm Based Signal Of Opportunity, Matthew B. P. Rapson
Passive Multistatic Radar Imaging Using An Ofdm Based Signal Of Opportunity, Matthew B. P. Rapson
Theses and Dissertations
This paper demonstrates a proof of concept in using an OFDM-based signal of opportunity for SAR imaging purposes within a passive, multistatic radar construct. Two signal processing methods have been proposed to create phase history data. The same methods are applied in both a simulated software model and an experimental data collection environment to produce simulated SAR images using the CBP imaging algorithm. The images generated from both the experimental and simulated data were observed to be consistent with each other and with expectations in terms of resolution. Coherent addition of the images results in improved image resolution due to …
Air-To-Air Missile Vector Scoring, Nicholas Sweeney
Air-To-Air Missile Vector Scoring, Nicholas Sweeney
Theses and Dissertations
An air-to-air missile vector scoring system is proposed for test and evaluation applications. Three different linear missile dynamics models are considered: a six-state constant velocity model and nine-state constant acceleration and three-dimensional coordinated turn models. Frequency modulated continuous wave radar sensors, carefully located to provide spherical coverage around the target, provide updates of missile kinematic information relative to a drone aircraft. Data from the radar sensors is fused with predictions from one of the three missile models using either an extended Kalman filter, an unscented Kalman filter or a particle filter algorithm. The performance of all nine model/filter combinations are …
Enhanced Image-Aided Navigation Algorithm With Automatic Calibration And Affine Distortion Prediction, Juan D. Jurado
Enhanced Image-Aided Navigation Algorithm With Automatic Calibration And Affine Distortion Prediction, Juan D. Jurado
Theses and Dissertations
This research aims at improving two key steps within the image aided navigation process: camera calibration and landmark tracking. The camera calibration step is improved by automating the point correspondence calculation within the standard camera calibration algorithm, thereby reducing the required time for calibration while maintaining the output model accuracy. The feature landmark tracking step is improved by digitally simulating affine distortions on input images in order to calculate more accurate feature descriptors for improved feature matching in high relative viewpoint change. These techniques are experimentally demonstrated in an outdoor environment with a consumer-grade inertial sensor and three imaging sensors, …