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Articles 1 - 30 of 80
Full-Text Articles in Physical Sciences and Mathematics
Direct Digital Synthesis: A Flexible Architecture For Advanced Signals Research For Future Satellite Navigation Payloads, Pranav R. Patel
Direct Digital Synthesis: A Flexible Architecture For Advanced Signals Research For Future Satellite Navigation Payloads, Pranav R. Patel
Theses and Dissertations
In legacy Global Positioning System (GPS) Satellite Navigation (SatNav) payloads, the architecture does not provide the flexibility to adapt to changing circumstances and environments. GPS SatNav payloads have largely remained unchanged since the system became fully operational in April 1995. Since then, the use of GPS has become ubiquitous in our day-to-day lives. GPS availability is now a basic assumption for distributed infrastructure; it has become inextricably tied to our national power grids, cellular networks, and global financial systems. Emerging advancements of easy to use radio technologies, such as software-defined radios (SDRs), have greatly lowered the difficulty of discovery and …
Physics-Constrained Hyperspectral Data Exploitation Across Diverse Atmospheric Scenarios, Nicholas M. Westing
Physics-Constrained Hyperspectral Data Exploitation Across Diverse Atmospheric Scenarios, Nicholas M. Westing
Theses and Dissertations
Hyperspectral target detection promises new operational advantages, with increasing instrument spectral resolution and robust material discrimination. Resolving surface materials requires a fast and accurate accounting of atmospheric effects to increase detection accuracy while minimizing false alarms. This dissertation investigates deep learning methods constrained by the processes governing radiative transfer to efficiently perform atmospheric compensation on data collected by long-wave infrared (LWIR) hyperspectral sensors. These compensation methods depend on generative modeling techniques and permutation invariant neural network architectures to predict LWIR spectral radiometric quantities. The compensation algorithms developed in this work were examined from the perspective of target detection performance using …
Design And Test Of An Autonomy Monitoring Service To Detect Divergent Behaviors On Unmanned Aerial Systems, Loay Y. Almannaei
Design And Test Of An Autonomy Monitoring Service To Detect Divergent Behaviors On Unmanned Aerial Systems, Loay Y. Almannaei
Theses and Dissertations
Operation of Unmanned Aerial Vehicles (UAV) support many critical missions in the United State Air Force (USAF). Monitoring abnormal behavior is one of many responsibilities of the operator during a mission. Some behaviors are hard to be detect by an operator, especially when flying one or more autonomous vehicles; as such, detections require a high level of attention and focus to flight parameters. In this research, a monitoring system and its algorithm are designed and tested for a target fixed-wing UAV. The Autonomy Monitoring Service (AMS) compares the real vehicle or simulated Vehicle with a similar simulated vehicle using Software …
Object Detection With Deep Learning To Accelerate Pose Estimation For Automated Aerial Refueling, Andrew T. Lee
Object Detection With Deep Learning To Accelerate Pose Estimation For Automated Aerial Refueling, Andrew T. Lee
Theses and Dissertations
Remotely piloted aircraft (RPAs) cannot currently refuel during flight because the latency between the pilot and the aircraft is too great to safely perform aerial refueling maneuvers. However, an AAR system removes this limitation by allowing the tanker to directly control the RP A. The tanker quickly finding the relative position and orientation (pose) of the approaching aircraft is the first step to create an AAR system. Previous work at AFIT demonstrates that stereo camera systems provide robust pose estimation capability. This thesis first extends that work by examining the effects of the cameras' resolution on the quality of pose …
Event-Based Visual-Inertial Odometry Using Smart Features, Zachary P. Friedel
Event-Based Visual-Inertial Odometry Using Smart Features, Zachary P. Friedel
Theses and Dissertations
Event-based cameras are a novel type of visual sensor that operate under a unique paradigm, providing asynchronous data on the log-level changes in light intensity for individual pixels. This hardware-level approach to change detection allows these cameras to achieve ultra-wide dynamic range and high temporal resolution. Furthermore, the advent of convolutional neural networks (CNNs) has led to state-of-the-art navigation solutions that now rival or even surpass human engineered algorithms. The advantages offered by event cameras and CNNs make them excellent tools for visual odometry (VO). This document presents the implementation of a CNN trained to detect and describe features within …
Comparison Of Visual Simultaneous Localization And Mapping Methods For Fixed-Wing Aircraft Using Slambench2, Patrick R. Latcham
Comparison Of Visual Simultaneous Localization And Mapping Methods For Fixed-Wing Aircraft Using Slambench2, Patrick R. Latcham
Theses and Dissertations
Visual Simultaneous Localization and Mapping (VSLAM) algorithms have evolved rapidly in the last few years, however there has been little research evaluating current algorithm's effectiveness and limitations when applied to tracking the position of a fixed-wing aerial vehicle. This research looks to evaluate current monocular VSLAM algorithms' performance on aerial vehicle datasets using the SLAMBench2 benchmarking suite. The algorithms tested are MonoSLAM, PTAM, OKVIS, LSDSLAM, ORB-SLAM2, and SVO, all of which are built into the SLAMBench2 software. The algorithms' performance is evaluated using simulated datasets generated in the AftrBurner Engine. The datasets were designed to test the quality of each …
Relational Database Design And Multi-Objective Database Queries For Position Navigation And Timing Data, Sean A. Mochocki
Relational Database Design And Multi-Objective Database Queries For Position Navigation And Timing Data, Sean A. Mochocki
Theses and Dissertations
Performing flight tests is a natural part of researching cutting edge sensors and filters for sensor integration. Unfortunately, tests are expensive, and typically take many months of planning. A sensible goal would be to make previously collected data readily available to researchers for future development. The Air Force Institute of Technology (AFIT) has hundreds of data logs potentially available to aid in facilitating further research in the area of navigation. A database would provide a common location where older and newer data sets are available. Such a database must be able to store the sensor data, metadata about the sensors, …
Maximizing Accuracy Through Stereo Vision Camera Positioning For Automated Aerial Refueling, Kirill A. Sarantsev
Maximizing Accuracy Through Stereo Vision Camera Positioning For Automated Aerial Refueling, Kirill A. Sarantsev
Theses and Dissertations
Aerial refueling is a key component of the U.S. Air Force strategic arsenal. When two aircraft interact in an aerial refueling operation, the accuracy of relative navigation estimates are critical for the safety, accuracy and success of the mission. Automated Aerial Refueling (AAR) looks to improve the refueling process by creating a more effective system and allowing for Unmanned Aerial Vehicle(s) (UAV) support. This paper considers a cooperative aerial refueling scenario where stereo cameras are used on the tanker to direct a \boom" (a large, long structure through which the fuel will ow) into a port on the receiver aircraft. …
Use Of Lidar In Automated Aerial Refueling To Improve Stereo Vision Systems, Michael R. Crowl
Use Of Lidar In Automated Aerial Refueling To Improve Stereo Vision Systems, Michael R. Crowl
Theses and Dissertations
The United States Air Force (USAF) executes five Core Missions, four of which depend on increased aircraft range. To better achieve global strike and reconnaissance, unmanned aerial vehicles (UAVs) require aerial refueling for extended missions. However, current aerial refueling capabilities are limited to manned aircraft due to technical difficulties to refuel UAVs mid-flight. The latency between a UAV operator and the UAV is too large to adequately respond for such an operation. To overcome this limitation, the USAF wants to create a capability to guide the refueling boom into the refueling receptacle. This research explores the use of light detection …
The Impact Of Changing The Size Of Aircraft Radar Displays On Visual Search In The Cockpit, Justin R. Marsh
The Impact Of Changing The Size Of Aircraft Radar Displays On Visual Search In The Cockpit, Justin R. Marsh
Theses and Dissertations
Advances in sensor technology have enabled our fighter aircraft to find, fix, track, target, engage (F2T2E) at greater distances, providing the operator with more data within the battlefield. Modern aircraft are designed with larger displays while our legacy aircraft are being retrofitted with larger cockpit displays to enable display of the increased data. While this modification has been shown to enable improvements in human performance of many cockpit tasks, this effect is often not measured nor fully understood at a more generalizable level. This research outlines an approach to comparing human performance across two display sizes in future F-16 cockpits. …
Pedestrian Navigation Using Artificial Neural Networks And Classical Filtering Techniques, David J. Ellis
Pedestrian Navigation Using Artificial Neural Networks And Classical Filtering Techniques, David J. Ellis
Theses and Dissertations
The objective of this thesis is to explore the improvements achieved through using classical filtering methods with Artificial Neural Network (ANN) for pedestrian navigation techniques. ANN have been improving dramatically in their ability to approximate various functions. These neural network solutions have been able to surpass many classical navigation techniques. However, research using ANN to solve problems appears to be solely focused on the ability of neural networks alone. The combination of ANN with classical filtering methods has the potential to bring beneficial aspects of both techniques to increase accuracy in many different applications. Pedestrian navigation is used as a …
Determining Virtual Practicality From Physical Stereo Vision Images And Gps, Bradley S. French
Determining Virtual Practicality From Physical Stereo Vision Images And Gps, Bradley S. French
Theses and Dissertations
Current research efforts for Automated Aerial Refueling (AAR) at The Air Force Institute of Technology (AFIT) utilize Stereo Computer Vision to compute a relative pose between a tanker and receiver aircraft. Due to costs, time, and availability, it can be onerous to test these algorithms using actual Air Force (AF) aircraft. Our solution to this problem consists of using a 3D Graphics Engine to simulate AAR endeavors. However, the question then arises, “Does the virtual world accurately represent the physical world?” This can be explored by comparing a set of truth data to a similar set of virtual data. First, …
The Trust-Based Interactive Partially Observable Markov Decision Process, Richard S. Seymour
The Trust-Based Interactive Partially Observable Markov Decision Process, Richard S. Seymour
Theses and Dissertations
Cooperative agent and robot systems are designed so that each is working toward the same common good. The problem is that the software systems are extremely complex and can be subverted by an adversary to either break the system or potentially worse, create sneaky agents who are willing to cooperate when the stakes are low and take selfish, greedy actions when the rewards rise. This research focuses on the ability of a group of agents to reason about the trustworthiness of each other and make decisions about whether to cooperate. A trust-based interactive partially observable Markov decision process (TI-POMDP) is …
Integrity Monitoring For Automated Aerial Refueling: A Stereo Vision Approach, Thomas R. Stuart
Integrity Monitoring For Automated Aerial Refueling: A Stereo Vision Approach, Thomas R. Stuart
Theses and Dissertations
Unmanned aerial vehicles (UAVs) increasingly require the capability to y autonomously in close formation including to facilitate automated aerial refueling (AAR). The availability of relative navigation measurements and navigation integrity are essential to autonomous relative navigation. Due to the potential non-availability of the global positioning system (GPS) during military operations, it is highly desirable that relative navigation can be accomplished without the use of GPS. This paper develops two algorithms designed to provide relative navigation measurements solely from a stereo image pair. These algorithms were developed and analyzed in the context of AAR using a stereo camera system modeling that …
Physical Layer Defenses Against Primary User Emulation Attacks, Joan A. Betances
Physical Layer Defenses Against Primary User Emulation Attacks, Joan A. Betances
Theses and Dissertations
Cognitive Radio (CR) is a promising technology that works by detecting unused parts of the spectrum and automatically reconfiguring the communication system's parameters in order to operate in the available communication channels while minimizing interference. CR enables efficient use of the Radio Frequency (RF) spectrum by generating waveforms that can coexist with existing users in licensed spectrum bands. Spectrum sensing is one of the most important components of CR systems because it provides awareness of its operating environment, as well as detecting the presence of primary (licensed) users of the spectrum.
Understanding Effects Of Autonomous Agent Timing On Human-Agent Teams Using Iterative Modeling, Simulation And Human-In-The-Loop Experimentation, Tyler J. Goodman
Understanding Effects Of Autonomous Agent Timing On Human-Agent Teams Using Iterative Modeling, Simulation And Human-In-The-Loop Experimentation, Tyler J. Goodman
Theses and Dissertations
Recent U.S. Air Force Research Laboratory strategy documents have suggested the need for research in human-agent teaming. Teaming supports a dynamic shift in roles between the human and the agent, depending upon human performance and mission needs. Further, because the performance of these agents will be highly dependent upon the state of the human and the mission, this strategy suggests the need for increased use of modeling to provide a broader understanding of the automated agent’s behavior. This thesis applies a combination of static modeling in SysML activity diagrams, dynamic modeling of human and agent behavior in IMPRINT, and human …
Adaptive Automation Design And Implementation, Jason M. Bindewald
Adaptive Automation Design And Implementation, Jason M. Bindewald
Theses and Dissertations
Automations allow us to reduce the need for humans in certain environments, such as auto-pilot features on unmanned aerial vehicles. However, some situations still require human intervention. Adaptive automation is a research field that enables computer systems to adjust the amount of automation by taking over tasks from or giving tasks back to the user. This research develops processes and insights for adaptive automation designers to take theoretical adaptive automation ideas and develop them into real-world adaptive automation system. These allow developers to design better automation systems that recognize the limits of computers systems, enabling better designs for systems in …
Effects Of Data Replication On Data Exfiltration In Mobile Ad Hoc Networks Utilizing Reactive Protocols, Corey T. Willinger
Effects Of Data Replication On Data Exfiltration In Mobile Ad Hoc Networks Utilizing Reactive Protocols, Corey T. Willinger
Theses and Dissertations
A swarm of autonomous UAVs can provide a significant amount of ISR data where current UAV assets may not be feasible or practical. As such, the availability of the data the resides in the swarm is a topic that will benefit from further investigation. This thesis examines the impact of le replication and swarm characteristics such as node mobility, swarm size, and churn rate on data availability utilizing reactive protocols. This document examines the most prominent factors affecting the networking of nodes in a MANET. Factors include network routing protocols and peer-to-peer le protocols. It compares and contrasts several open …
Examining The Return On Investment Of Test And Evaluation, Nathan C. Smith
Examining The Return On Investment Of Test And Evaluation, Nathan C. Smith
Theses and Dissertations
This research examined the return on investment of Department of Defense test and evaluation. The thesis analyzed the return on investment of the cost avoidance achieved if an issue discovered late in the program had been discovered and corrected during developmental test and evaluation. The methodology utilized two case study examples from the Joint Primary Training Aircraft System to calculate the potential cost avoidance and the potential return on investment if the program had discovered and corrected the issues during developmental test and evaluation. The result of one case was a 9,260% return on investment. The other case results ranged …
Distributed Kernelized Locality-Sensitive Hashing For Faster Image Based Navigation, Scott A. Hutchison
Distributed Kernelized Locality-Sensitive Hashing For Faster Image Based Navigation, Scott A. Hutchison
Theses and Dissertations
Content based image retrieval (CBIR) remains one of the most heavily researched areas in computer vision. Different image retrieval techniques and algorithms have been implemented and used in localization research, object recognition applications, and commercially by companies such as Facebook, Google, and Yahoo!. Current methods for image retrieval become problematic when implemented on image datasets that can easily reach billions of images. In order to process extremely large datasets, the computation must be distributed across a cluster of machines using software such as Apache Hadoop. There are many different algorithms for conducting content based image retrieval, but this research focuses …
The Dynamic Multi-Objective Multi-Vehicle Covering Tour Problem, Joshua S. Ziegler
The Dynamic Multi-Objective Multi-Vehicle Covering Tour Problem, Joshua S. Ziegler
Theses and Dissertations
This work introduces a new routing problem called the Dynamic Multi-Objective Multi-vehicle Covering Tour Problem (DMOMCTP). The DMOMCTPs is a combinatorial optimization problem that represents the problem of routing multiple vehicles to survey an area in which unpredictable target nodes may appear during execution. The formulation includes multiple objectives that include minimizing the cost of the combined tour cost, minimizing the longest tour cost, minimizing the distance to nodes to be covered and maximizing the distance to hazardous nodes. This study adapts several existing algorithms to the problem with several operator and solution encoding variations. The efficacy of this set …
Mobile Network Defense Interface For Cyber Defense And Situational Awareness, James C. Hannan
Mobile Network Defense Interface For Cyber Defense And Situational Awareness, James C. Hannan
Theses and Dissertations
Today's computer networks are under constant attack. In order to deal with this constant threat, network administrators rely on intrusion detection and prevention services (IDS) (IPS). Most IDS and IPS implement static rule sets to automatically alert administrators and resolve intrusions. Network administrators face a difficult challenge, identifying attacks against a vast number of benign network transactions. Also after a threat is identified making even the smallest policy change to the security software potentially has far-reaching and unanticipated consequences. Finally, because the administrator is primarily responding to alerts they may lose situational awareness of the network. During this research a …
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 …
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, …
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 …
A Dempster-Shafer Method For Multi-Sensor Fusion, Bethany G. Foley
A Dempster-Shafer Method For Multi-Sensor Fusion, Bethany G. Foley
Theses and Dissertations
The Dempster-Shafer Theory, a generalization of the Bayesian theory, is based on the idea of belief and as such can handle ignorance. When all of the required information is available, many data fusion methods provide a solid approach. Yet, most do not have a good way of dealing with ignorance. In the absence of information, these methods must then make assumptions about the sensor data. However, the real data may not fit well within the assumed model. Consequently, the results are often unsatisfactory and inconsistent. The Dempster-Shafer Theory is not hindered by incomplete models or by the lack of prior …
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 …
Context Aided Tracking With Adaptive Hyperspectral Imagery, Andrew C. Rice
Context Aided Tracking With Adaptive Hyperspectral Imagery, Andrew C. Rice
Theses and Dissertations
A methodology for the context-aided tracking of ground vehicles in remote airborne imagery is developed in which a background model is inferred from hyperspectral imagery. The materials comprising the background of a scene are remotely identified and lead to this model. Two model formation processes are developed: a manual method, and method that exploits an emerging adaptive, multiple-object-spectrometer instrument. A semi-automated background modeling approach is shown to arrive at a reasonable background model with minimal operator intervention. A novel, adaptive, and autonomous approach uses a new type of adaptive hyperspectral sensor, and converges to a 66% correct background model in …