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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Performance Analysis Of Angle Of Arrival Algorithms Applied To Radiofrequency Interference Direction Finding, Taylor S. Barber
Performance Analysis Of Angle Of Arrival Algorithms Applied To Radiofrequency Interference Direction Finding, Taylor S. Barber
Theses and Dissertations
Radiofrequency (RF) interference threatens the functionality of systems that increasingly underpin the daily function of modern society. In recent years there have been multiple incidents of intentional RF spectrum denial using terrestrial interference sources. Because RF based systems are used in safety-of-life applications in both military and civilian contexts, there is need for systems that can quickly locate these interference sources. In order to meet this need, the Air Force Research Laboratory Weapons Directorate is sponsoring the following research to support systems that will be able to quickly geolocate RF interferers using passive angle-of-arrival estimation to triangulate interference sources. This …
High Fidelity Satellite Navigation Receiver Front-End For Advanced Signal Quality Monitoring And Authentication, Andrew D. Braun
High Fidelity Satellite Navigation Receiver Front-End For Advanced Signal Quality Monitoring And Authentication, Andrew D. Braun
Theses and Dissertations
Over the last several years, interest in utilizing foreign satellite timing and navigation (satnav) signals to augment GPS has grown. Doing so is not without risks; foreign satnav signals must be vetted and determined to be trustworthy before use in military applications. Advanced signal quality monitoring methods can help to ensure that only authentic and reliable satnav signals are utilized. To effectively monitor and authenticate signals, the front-end must impress as little distortions upon the received signal as possible. The purpose of this study is to design, fabricate, and test the performance of a high-fidelity satnav receiver front-end for advanced …
Cyber-Attack Drone Payload Development And Geolocation Via Directional Antennae, Clint M. Bramlette
Cyber-Attack Drone Payload Development And Geolocation Via Directional Antennae, Clint M. Bramlette
Theses and Dissertations
The increasing capabilities of commercial drones have led to blossoming drone usage in private sector industries ranging from agriculture to mining to cinema. Commercial drones have made amazing improvements in flight time, flight distance, and payload weight. These same features also offer a unique and unprecedented commodity for wireless hackers -- the ability to gain ‘physical’ proximity to a target without personally having to be anywhere near it. This capability is called Remote Physical Proximity (RPP). By their nature, wireless devices are largely susceptible to sniffing and injection attacks, but only if the attacker can interact with the device via …
Convolutional Neural Network Architecture Study For Aerial Visual Localization, Jedediah M. Berhold
Convolutional Neural Network Architecture Study For Aerial Visual Localization, Jedediah M. Berhold
Theses and Dissertations
In unmanned aerial navigation the ability to determine the aircraft's location is essential for safe flight. The Global Positioning System (GPS) is the default modern application used for geospatial location determination. GPS is extremely robust, very accurate, and has essentially solved aerial localization. Unfortunately, the signals from all Global Navigation Satellite Systems (GNSS) to include GPS can be jammed or spoofed. To this response it is essential to develop alternative systems that could be used to supplement navigation systems, in the event of a lost GNSS signal. Public and governmental satellites have provided large amounts of high-resolution satellite imagery. These …
Monocular Visual Odometry For Fixed-Wing Small Unmanned Aircraft Systems, Kyung M. Kim
Monocular Visual Odometry For Fixed-Wing Small Unmanned Aircraft Systems, Kyung M. Kim
Theses and Dissertations
The popularity of small unmanned aircraft systems (SUAS) has exploded in recent years and seen increasing use in both commercial and military sectors. A key interest area for the military is to develop autonomous capabilities for these systems, of which navigation is a fundamental problem. Current navigation solutions suffer from a heavy reliance on a Global Positioning System (GPS). This dependency presents a significant limitation for military applications since many operations are conducted in environments where GPS signals are degraded or actively denied. Therefore, alternative navigation solutions without GPS must be developed and visual methods are one of the most …
Aerial Simultaneous Localization And Mapping Using Earth's Magnetic Anomaly Field, Taylor N. Lee
Aerial Simultaneous Localization And Mapping Using Earth's Magnetic Anomaly Field, Taylor N. Lee
Theses and Dissertations
Aerial magnetic navigation has been shown to be a viable GPS-alternative, but requires a prior-surveyed magnetic map. The miniaturization of atomic magnetometers extends their application to small aircraft at low altitudes where magnetic maps are especially inaccurate or unavailable. This research presents a simultaneous localization and mapping (SLAM) approach to constrain the drift of an inertial navigation system (INS) without the need for a magnetic map. The filter was demonstrated using real measurements on a professional survey flight, and on an AFIT unmanned aerial vehicle.
Analysis Of Satellite Timing And Navigation Receiver Pseudorange Biases Due To Spreading Code Puncturing And Phase Optimized Constant Envelope Transmission, Nathaniel J. Raquet
Analysis Of Satellite Timing And Navigation Receiver Pseudorange Biases Due To Spreading Code Puncturing And Phase Optimized Constant Envelope Transmission, Nathaniel J. Raquet
Theses and Dissertations
There is a desire for future GPS satellites to be software-defined to enable greater operational flexibility and adapt to a variety of current and future threats. This includes implementing new modulation techniques such as phase optimized constant envelope transmission (POCET) and asymmetric signal authentication methods such as chips message robust authentication (Chimera). Any new GPS signal transmitted must be backwards compatible with the millions of receivers already in use. This thesis shows a variety of tests performed to demonstrate the effects of Chimera and POCET-enabled signals. It is shown through actual radio frequency signal generation, testing the response of current-generation …
Verification Of Autonomous Systems: Developmental Test And Evaluation Of An Autonomous Uas Swarming Algorithm Combining Simulation, Formulation And Live Flight, Corey A. Combs
Theses and Dissertations
This research was driven by the increase of autonomous systems in the current millennium and the challenging nature of testing and evaluating their performance. A review of the current literature revealed proposed methods for verifying autonomous systems, but few implementations. It exposed several gaps in the current verification and validation methods and suggested goals for filling them. Through the use of modeling, software in the loop (SITL), and flight test, this research verified an autonomous swarming algorithm for unmanned aerial systems (UAS) and validated an exemplar of a testing framework. Thirteen sets of three-vehicle swarm data produced over two days …
Simulation And Piloted Simulator Study Of An Automatic Ground Collision Avoidance System For Performance Limited Aircraft, James D. Carpenter
Simulation And Piloted Simulator Study Of An Automatic Ground Collision Avoidance System For Performance Limited Aircraft, James D. Carpenter
Theses and Dissertations
The F-16 Automatic-Ground Collision Avoidance System (Auto-GCAS) has been a resounding success since implementation in Nov 2014, saving 8 pilots and 7 aircraft from Controlled Flight into Terrain (CFIT). However, there is no implemented Auto- GCAS for "heavy" performance limited aircraft. This research endeavors to expand on the success of F-16 Auto-GCAS to other aircraft in the Air Force inventory such as the C-130, C-17, and B-1. MIL-STD-1797 classifies performance limited aircraft as large, heavy, and low to medium maneuverability. Using a stitched Learjet-25D model (LJ-25D), an Auto-GCAS algorithm was developed to predict multiple escape-maneuver trajectories, compare these paths to …
Multi-Path Automatic Ground Collision Avoidance System For Performance Limited Aircraft With Flight Tests: Project Have Medusa, Kenneth C. Gahan
Multi-Path Automatic Ground Collision Avoidance System For Performance Limited Aircraft With Flight Tests: Project Have Medusa, Kenneth C. Gahan
Theses and Dissertations
A multi-path automatic ground collision avoidance system (Auto-GCAS) for performance limited aircraft was further developed and improved to prevent controlled flight into terrain. This research includes flight test results from the United States Test Pilot School's Test Management Project (TMP) titled Have Multi-Path Escape Decisions Using Sophisticated Algorithms (MEDUSA). Currently, the bomber and mobility air- craft communities lack an Auto-GCAS. The F-16 Auto-GCAS was proven successful for fighter-type aircraft with seven aircraft and eight lives saved from 2014 to 2018. The newly developed and tested Rapidly Selectable Escape Trajectory (RSET) sys- tem included a 5-path implementation which continuously updated at …
A Mixed Integer Programming Framework For The Fuel Optimal Guidance Of Complex Spacecraft Rendezvous And Proximity Operation Missions, Andrew S. Levalley
A Mixed Integer Programming Framework For The Fuel Optimal Guidance Of Complex Spacecraft Rendezvous And Proximity Operation Missions, Andrew S. Levalley
Theses and Dissertations
Space is a contested, congested, and competitive environment where space situational awareness (SSA) is a key factor in the long term sustainability of space as a national interest. Space-based SSA conducted by inspector satellites is critical to the detecting, tracking, and attribution of actions in space. Thus, space-based fuel-optimal maneuvers are essential to increasing mission life and improving the capability of inspector satellites working to characterize resident space objects (RSOs) in geosynchronous orbit (GEO). Additionally, on-orbit inspection missions can be characterized by multiple waypoint visits where an inspector is accomplishing a set of proximity operation mission objectives through the visit …
Evaluation Of Unmanned Aircraft Flying Qualities Using A Stitched Learjet Model, Patrick M. Callaghan
Evaluation Of Unmanned Aircraft Flying Qualities Using A Stitched Learjet Model, Patrick M. Callaghan
Theses and Dissertations
In recent years, military UAVs have taken over missions that were too dull, dirty, or dangerous for manned aircraft. The increased demand has led to a build-fly-fix-fly development mentality, plaguing the early lifecycle with staggering mishap rates. Currently, MIL-STD-1797 lists flying qualities for UAVs as TBD, and the standards for manned fixed wing are inadequate when applied to UAVs. In an effort to expand the database of UAV flying qualities, an analysis was completed on a Simulink model of an LJ-25D developed from Calspans Variable Stability System aircraft at the United States Test Pilot School. Three maneuvers were simulated: (1) …
Magnetic Field Aided Indoor Navigation, William F. Storms
Magnetic Field Aided Indoor Navigation, William F. Storms
Theses and Dissertations
This research effort examines inertial navigation system aiding using magnetic field intensity data and a Kalman filter in an indoor environment. Many current aiding methods do not work well in an indoor environment, like aiding using the Global Positioning System. The method presented in this research uses magnetic field intensity data from a three-axis magnetometer in order to estimate position using a maximum – likelihood approach. The position measurements are then combined with a motion model using a Kalman filter. The magnetic field navigation algorithm is tested using a combination of simulated and real measurements. These tests are conducted using …