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Articles 1 - 28 of 28
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Forensics Image Background Matching Using Scale Invariant Feature (Sift)Transform And Speeded Up Robust Features (Surf), Paul N. Fogg Ii
Forensics Image Background Matching Using Scale Invariant Feature (Sift)Transform And Speeded Up Robust Features (Surf), Paul N. Fogg Ii
Theses and Dissertations
In criminal investigations, it is not uncommon for investigators to obtain a photograph or image that shows a crime being committed. Additionally, thousands of pictures may exist of a location, taken from the same or varying viewpoints. Some of these images may even include a criminal suspect or witness. One mechanism to identify criminals and witnesses is to group the images found on computers, cell phones, cameras, and other electronic devices into sets representing the same location. One or more images in the group may then prove the suspect was at the crime scene before, during, and/or after a crime. …
A Unified Framework For Solving Multiagent Task Assignment Problems, Kevin Cousin
A Unified Framework For Solving Multiagent Task Assignment Problems, Kevin Cousin
Theses and Dissertations
Multiagent task assignment problem descriptors do not fully represent the complex interactions in a multiagent domain, and algorithmic solutions vary widely depending on how the domain is represented. This issue is compounded as related research fields contain descriptors that similarly describe multiagent task assignment problems, including complex domain interactions, but generally do not provide the mechanisms needed to solve the multiagent aspect of task assignment. This research presents a unified approach to representing and solving the multiagent task assignment problem for complex problem domains. Ideas central to multiagent task allocation, project scheduling, constraint satisfaction, and coalition formation are combined to …
A Hybrid Multi-Robot Control Architecture, Daylond J. Hooper
A Hybrid Multi-Robot Control Architecture, Daylond J. Hooper
Theses and Dissertations
Multi-robot systems provide system redundancy and enhanced capability versus single robot systems. Implementations of these systems are varied, each with specific design approaches geared towards an application domain. Some traditional single robot control architectures have been expanded for multi-robot systems, but these expansions predominantly focus on the addition of communication capabilities. Both design approaches are application specific and limit the generalizability of the system. This work presents a redesign of a common single robot architecture in order to provide a more sophisticated multi-robot system. The single robot architecture chosen for application is the Three Layer Architecture (TLA). The primary strength …
Multi-Objective Optimization For Speed And Stability Of A Sony Aibo Gait, Christopher A. Patterson
Multi-Objective Optimization For Speed And Stability Of A Sony Aibo Gait, Christopher A. Patterson
Theses and Dissertations
Locomotion is a fundamental facet of mobile robotics that many higher level aspects rely on. However, this is not a simple problem for legged robots with many degrees of freedom. For this reason, machine learning techniques have been applied to the domain. Although impressive results have been achieved, there remains a fundamental problem with using most machine learning methods. The learning algorithms usually require a large dataset which is prohibitively hard to collect on an actual robot. Further, learning in simulation has had limited success transitioning to the real world. Also, many learning algorithms optimize for a single fitness function, …
Common Aero Vehicle Autonomous Reentry Trajectory Optimization Satisfying Waypoint And No-Fly Zone Constraints, Timothy R. Jorris
Common Aero Vehicle Autonomous Reentry Trajectory Optimization Satisfying Waypoint And No-Fly Zone Constraints, Timothy R. Jorris
Theses and Dissertations
To support the Global Strike mission, an autonomous trajectory optimization technique is presented to minimize the flight time, satisfy terminal and intermediate constraints, and remain within the specified vehicle heating and control limitations. "Waypoints" are specified for reconnaissance or multiple payload deployments and "no-fly zones" are specified for geopolitical restrictions or threat avoidance. The Hypersonic Cruise Vehicle (HCV) is used as a simplified two-dimensional platform to compare multiple solution techniques. The solution techniques include a unique geometric approach, an analytical dynamic optimization technique, and a numerical approach. This numerical technique is a direct solution method involving pseudospectral methods and nonlinear …
Efficient Gps Position Determination Algorithms, Thao Nguyen
Efficient Gps Position Determination Algorithms, Thao Nguyen
Theses and Dissertations
This research is aimed at improving the state of the art of GPS algorithms, namely, the development of a closed-form positioning algorithm for a standalone user and the development of a novel differential GPS algorithm for a network of users. The stand-alone user GPS algorithm is a direct, closed-form, and efficient new position determination algorithm that exploits the closed-form solution of the GPS trilateration equations and works in the presence of pseudorange measurement noise for an arbitrary number of satellites in view. A two-step GPS position determination algorithm is derived which entails the solution of a linear regression and updates …
Real-Time Gps-Alternative Navigation Using Commodity Hardware, Jordon L. Fletcher
Real-Time Gps-Alternative Navigation Using Commodity Hardware, Jordon L. Fletcher
Theses and Dissertations
Modern navigation systems can use the Global Positioning System (GPS) to accurately determine position with precision in some cases bordering on millimeters. Unfortunately, GPS technology is susceptible to jamming, interception, and unavailability indoors or underground. There are several navigation techniques that can be used to navigate during times of GPS unavailability, but there are very few that result in GPS-level precision. One method of achieving high precision navigation without GPS is to fuse data obtained from multiple sensors. This thesis explores the fusion of imaging and inertial sensors and implements them in a real-time system that mimics human navigation. In …
Development Of Cursor-On-Target Control For Semi-Autonomous Unmanned Aircraft Systems, Joshua D. Crouse
Development Of Cursor-On-Target Control For Semi-Autonomous Unmanned Aircraft Systems, Joshua D. Crouse
Theses and Dissertations
The research presented in this thesis focuses on developing, demonstrating, and evaluating the concept of a Cursor-on-Target control system for semi-autonomous unmanned aircraft systems. The Department of Defense has mapped out a strategy in which unmanned aircraft systems will increasingly replace piloted aircraft. During most phases of flight autonomous unmanned aircraft control reduces operator workload, however, real-time information exchange often requires an operator to relay decision changes to the unmanned aircraft. The goal of this research is to develop a preliminary Cursor-on-Target control system to enable the operator to guide the unmanned aircraft with minimal workload during high task phases …
Automated Carrier Landing Of An Unmanned Combat Aerial Vehicle Using Dynamic Inversion, Nicholas A. Denison
Automated Carrier Landing Of An Unmanned Combat Aerial Vehicle Using Dynamic Inversion, Nicholas A. Denison
Theses and Dissertations
Dynamic Inversion (DI) is a powerful nonlinear control technique which has been applied to several modern flight control systems. This research utilized concepts of DI in order to develop a controller to land an Unmanned Combat Aerial Vehicle (UCAV) on an aircraft carrier. The Joint Unmanned Combat Air System (J-UCAS) Equivalent Model was used as the test aircraft. An inner-loop DI controller was developed to control the pitch, roll, and yaw rate dynamics of the aircraft, while an outer-loop DI controller was developed to provide flight path commands to the inner-loop. The controller design and simulation were conducted in the …
A Small-Scale 3d Imaging Platform For Algorithm Performance Evaluation, Steven A. James
A Small-Scale 3d Imaging Platform For Algorithm Performance Evaluation, Steven A. James
Theses and Dissertations
In recent years, world events have expedited the need for the design and application of rapidly deployable airborne surveillance systems in urban environments. Fast and effective use of the surveillance images requires accurate modeling of the terrain being surveyed. The process of accurately modeling buildings, landmarks, or other items of interest on the surface of the earth, within a short lead time, has proven to be a challenging task. One approach of high importance for countering this challenge and accurately reconstructing 3D objects is through the employment of airborne 3D image acquisition platforms. While developments in this arena have significantly …
Controller Design For Accurate Antenna Pointing Onboard A Spacecraft, Victor M. Barba
Controller Design For Accurate Antenna Pointing Onboard A Spacecraft, Victor M. Barba
Theses and Dissertations
Controller design for a spacecraft mounted flexible antenna is considered. The antenna plant model has a certain degree of uncertainty. Additionally, disturbances from the host spacecraft are transmitted to the antenna and need to be attenuated. The design concept explored herein entails feedforward control to slew the antenna. Feedback control is then used to compensate for plant uncertainty and to reject the disturbance signals. A tight control loop is designed to meet performance specifications while minimizing the control gains. Simulations are conducted to show that the integration of feedforward control action and feedback compensation produces better responses than the implementation …
Performance Analysis And Comparison Of Multiple Routing Protocols In A Large-Area, High Speed Mobile Node Ad Hoc Network, Daniel K. Roberts
Performance Analysis And Comparison Of Multiple Routing Protocols In A Large-Area, High Speed Mobile Node Ad Hoc Network, Daniel K. Roberts
Theses and Dissertations
The U.S. Air Force is interested in developing a standard ad hoc framework using "heavy" aircraft to route data across large regions. The Zone Routing Protocol (ZRP) has the potential to provide seamless large-scale routing for DOD under the Joint Tactical Radio System program. The goal of this study is to determine if there is a difference between routing protocol performance when operating in a large-area MANET with high-speed mobile nodes. This study analyzes MANET performance when using reactive, proactive, and hybrid routing protocols, specifically AODV, DYMO, Fisheye, and ZRP. This analysis compares the performance of the four routing protocols …
Holes: Ionospheric Scintillation, Gps And Imputation, Robert A. Steenburgh
Holes: Ionospheric Scintillation, Gps And Imputation, Robert A. Steenburgh
Theses and Dissertations
Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active, although not limited to, a belt encircling the earth within ± 20 degrees of the geomagnetic equator. This belt also hosted roughly half of the completed U.S. military operations in the last decade. The authors examined scintillation data from Ascension Island, United Kingdom, and Ancon, Peru, in the Atlantic longitudinal sector as well as data from Parepare, Indonesia, and Marak Parak, Malaysia, in the Pacific longitudinal sector. From these data, they calculate percent probability of occurrence …
Development Of An Experimental Platform For Testing Autonomous Uav Guidance And Control Algorithms, Justin R. Rufa
Development Of An Experimental Platform For Testing Autonomous Uav Guidance And Control Algorithms, Justin R. Rufa
Theses and Dissertations
With the United States' push towards using unmanned aerial vehicles (UAVs) for more military missions, wide area search theory is being researched to determine the viability of multiple vehicle autonomous searches over the battle area. Previous work includes theoretical development of detection and attack probabilities while taking into account known enemy presence within the search environment. Simulations have been able to transform these theories into code to predict the UAV performance against known numbers of true and false targets. The next step to transitioning these autonomous search algorithms to an operational environment is the experimental testing of these theories through …
Optimal Wind Corrected Flight Path Planning For Autonomous Micro Air Vehicles, Michael D. Zollars
Optimal Wind Corrected Flight Path Planning For Autonomous Micro Air Vehicles, Michael D. Zollars
Theses and Dissertations
This research effort focuses on determining the optimal flight path required to put a micro air vehicle's (MAVs) fixed sensor on a target in the presence of a constant wind. Autonomous flight is quickly becoming the future of air power and over the past several years, the size and weight of autonomous vehicles has decreased dramatically. As these vehicles were implemented into the field, it was quickly discovered that their flight paths are severely altered by wind. However, since the size of the vehicle does not allow for a gimbaled camera, only a slight perturbation to the attitude of the …
Autonomous Unmarked Aerial Rendezvous For Automated Aerial Refueling (Aar), Brian S. Burns
Autonomous Unmarked Aerial Rendezvous For Automated Aerial Refueling (Aar), Brian S. Burns
Theses and Dissertations
As unmanned aerial vehicles (UAVs) increase in capability, the ability to refuel them in the air is becoming more critical. Aerial refueling will extend the range, shorten the response times, and extend loiter time of UAVs. Executing aerial refueling autonomously will reduce the command and control, logistics, and training efforts associated with fielding UAV systems. Currently, the Air Force Research Lab is researching the various technologies required to conduct automated aerial refueling (AAR). One of the required technologies is the ability to autonomously rendezvous with the tanker. The goal of this research is to determine the control required to fly …
Wide Area Search And Engagement Simulation Validation, Michael J. Marlin
Wide Area Search And Engagement Simulation Validation, Michael J. Marlin
Theses and Dissertations
As unmanned aerial vehicles (UAVs) increase in capability, the ability to refuel them in the air is becoming more critical. Aerial refueling will extend the range, shorten the response times, and extend loiter time of UAVs. Executing aerial refueling autonomously will reduce the command and control, logistics, and training efforts associated with fielding UAV systems. Currently, the Air Force Research Lab is researching the various technologies required to conduct automated aerial refueling (AAR). One of the required technologies is the ability to autonomously rendezvous with the tanker. The goal of this research is to determine the control required to fly …
An Analysis Of Aircraft Handling Quality Data Obtained From Boundary Avoidance Tracking Flight Test Techniques, Jason D. Dotter
An Analysis Of Aircraft Handling Quality Data Obtained From Boundary Avoidance Tracking Flight Test Techniques, Jason D. Dotter
Theses and Dissertations
Cooper-Harper ratings (CHRs) have been used to describe and compare aircraft handling qualities for over 40 years, but are by their very nature, subjective. The subjective and sometimes ambiguous results obtained from qualitative handling quality ratings are inconsistent with the rest of the flight test process, where quantifiable results followed by statistical analysis are the norm. This thesis presents a method for obtaining accurate and consistent flight test data that quantifies the handling qualities of a specific aircraft. The method is demonstrated using both pilot-in-the-loop simulations and flight tests with the NF-16D Variable-Stability In-Flight Simulator Test Aircraft (VISTA). Boundary Avoidance …
Optimal Sensor Threshold Control And The Weapon Operating Characteristic For Autonomous Search And Attack Munitions, Roland A. Rosario
Optimal Sensor Threshold Control And The Weapon Operating Characteristic For Autonomous Search And Attack Munitions, Roland A. Rosario
Theses and Dissertations
This Thesis considers the optimal employment of a wide area search munition in a battlespace where a target is known to be uniformly distributed among false targets which are Poisson distributed. The Poisson distribution's parameter is obtained from readily available battlespace intelligence. This work formulates and solves the optimal control problem for deriving the optimal sensor threshold schedule in order to maximize the probability of attacking the target during the battlespace sweep while constraining the probability of attacking a false target. The efficiency gained by optimally varying the sensor threshold is compared against the performance achieved with a static, optimum …
Use Of Two-Way Time Transfer Measurements To Improve Geostationary Satellite Navigation, Benjamin G. Dainty
Use Of Two-Way Time Transfer Measurements To Improve Geostationary Satellite Navigation, Benjamin G. Dainty
Theses and Dissertations
An emerging use of GPS is to provide accurate navigation information for satellites in orbit. The GPS satellites are designed to provide service to terrestrial users, so the antenna array points directly towards the Earth and uses a narrow primary beamwidth. Because GEO altitudes are well above the GPS constellation, the Earth occludes most of the GPS signals to the satellite. Decreased satellite visibility is debilitating, as GPS navigation requires at least four visible satellites to determine position. To assist with the visibility problem, the receiver can look at the GPS satellite transmit antenna side lobes, but this does not …
Sub-Surface Navigation Using Very-Low Frequency Electromagnetic Waves, Alan L. Harner
Sub-Surface Navigation Using Very-Low Frequency Electromagnetic Waves, Alan L. Harner
Theses and Dissertations
This research proposes two schemes utilizing very-low frequency (VLF) electromagnetic waves to navigate underground. The first scheme consists of using above-ground beacon transmitters to broadcast VLF signals to an underground mobile receiver which uses methods such as triangulation and trilateration to obtain a position solution. The second scheme consists of using above-ground reference receivers along with an underground mobile receiver to form time-difference- of-arrival measurements of incoming VLF signals of opportunity, such as lightning strike emissions, to calculate a position solution. The objective of this thesis is to develop positioning algorithms and use simulations as a tool to characterize the …
Distributed Fault-Tolerant Quality Of Service Routing In Hybrid Directional Wireless Networks, Larry C. Llewellyn Ii
Distributed Fault-Tolerant Quality Of Service Routing In Hybrid Directional Wireless Networks, Larry C. Llewellyn Ii
Theses and Dissertations
This thesis presents a distributed fault-tolerant routing protocol (EFDCB) for QoS supporting hybrid mobile ad hoc networks with the aim of mitigating QoS disruption time when network failures occur. The experimental design presented in this thesis describes 22 experiments aimed at illustrating EFDCB's ability to handle fault-tolerance. The interpreted results show that EFDCB excels over a global rerouting protocol at this challenge which is the goal of this work.
Heuristically Driven Search Methods For Topology Control In Directional Wireless Hybrid Network, Roger L. Garner
Heuristically Driven Search Methods For Topology Control In Directional Wireless Hybrid Network, Roger L. Garner
Theses and Dissertations
Information and Networked Communications play a vital role in the everyday operations of the United States Armed Forces. This research establishes a comparative analysis of the unique network characteristics and requirements introduced by the Topology Control Problem (also known as the Network Design Problem). Previous research has focused on the development of Mixed-Integer Linear Program (MILP) formulations, simple heuristics, and Genetic Algorithm (GA) strategies for solving this problem. Principal concerns with these techniques include runtime and solution quality. To reduce runtime, new strategies have been developed based on the concept of flow networks using the novel combination of three well-known …
Passive Geolocation Of Low Power Emitters In Urban Environments Using Tdoa, Myrna B. Montminy
Passive Geolocation Of Low Power Emitters In Urban Environments Using Tdoa, Myrna B. Montminy
Theses and Dissertations
Low-power devices are commonly used by the enemy to control Improvised Explosive Devices (IEDs), and as communications nodes for command and control. Quickly locating the source of these signals is difficult, especially in an urban environment where buildings and towers can cause interference. This research presents a geolocation system that combines several geolocation and error mitigation methods to locate an emitter in an urban environment. The proposed geolocation system uses a Time Difference of Arrival (TDOA) technique to estimate the location of the emitter of interest. Using sensors at known locations, TDOA estimates are obtained by cross-correlating the signal received …
Multi-Robot Fastslam For Large Domains, Choyong G. Koperski
Multi-Robot Fastslam For Large Domains, Choyong G. Koperski
Theses and Dissertations
For a robot to build a map of its surrounding area, it must have accurate position information within the area, and to obtain accurate position information within the area, the robot needs to have an accurate map of the area. This circular problem is the Simultaneous Localization and Mapping (SLAM) problem. An efficient algorithm to solve it is FastSLAM, which is based on the Rao-Blackwellized particle filter. FastSLAM solves the SLAM problem for single-robot mapping using particles to represent the posterior of the robot pose and the map. Each particle of the filter possesses its own global map which is …
Unified Behavior Framework For Reactive Robot Control In Real-Time Systems, Brian G. Woolley
Unified Behavior Framework For Reactive Robot Control In Real-Time Systems, Brian G. Woolley
Theses and Dissertations
Endeavors in mobile robotics focus on developing autonomous vehicles that operate in dynamic and uncertain environments. By reducing the need for human-in- the-loop control, unmanned vehicles are utilized to achieve tasks considered dull or dangerous by humans. Because unexpected latency can adversely affect the quality of an autonomous system's operations, which in turn can affect lives and property in the real-world, their ability to detect and handle external events is paramount to providing safe and dependable operation. Behavior-based systems form the basis of autonomous control for many robots. This thesis presents the unified behavior framework, a new and novel approach …
Performance Evaluation Of Ad Hoc Routing In A Swarm Of Autonomous Aerial Vehicles, Matthew T. Hyland
Performance Evaluation Of Ad Hoc Routing In A Swarm Of Autonomous Aerial Vehicles, Matthew T. Hyland
Theses and Dissertations
This thesis investigates the performance of three mobile ad hoc routing protocols in the context of a swarm of autonomous unmanned aerial vehicles (UAVs). It is proposed that a wireless network of nodes having an average of 5.1774 log n neighbors, where n is the total number of nodes in the network, has a high probability of having no partitions. By decreasing transmission range while ensuring network connectivity, and implementing multi-hop routing between nodes, spatial multiplexing is exploited whereby multiple pairs of nodes simultaneously transmit on the same channel. The proposal is evaluated using the Greedy Perimeter Stateless Routing (GPSR), …
Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey
Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey
Theses and Dissertations
An extended Kalman filter is used to estimate size and packet arrival rate of network queues. These estimates are used by a LQG steady state linear perturbation PI controller to regulate queue size within a computer network. This paper presents the derivation of the transient queue behavior for a system with Poisson traffic and exponential service times. This result is then validated for ideal traffic using a network simulated in OPNET. A more complex OPNET model is then used to test the adequacy of the transient queue size model when non-Poisson traffic is combined. The extended Kalman filter theory is …