Aerospace Engineering Commons^™

A High-Quality Mach-Zehnder Interferometer Fiber Sensor By Femtosecond Laser One-Step Processing, Longjiang Zhao, Lan Jiang, Sumei Wang, Hai Xiao, Yongfeng Lu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During new fiber sensor development experiments, an easy-to-fabricate simple sensing structure with a trench and partially ablated fiber core is fabricated by using an 800 nm 35 fs 1 kHz laser. It is demonstrated that the structure forms a Mach-Zehnder interferometer (MZI) with the interference between the laser light passing through the air in the trench cavity and that in the remained fiber core. The fringe visibilities are all more than 25 dB. The transmission spectra vary with the femtosecond (fs) laser ablation scanning cycle. The free spectral range (FSR) decreases as the trench length increases. The MZI structure is …

Modeling Of A Gyro-Stabilized Helicopter Camera System Using Neural Networks, Nicholas Joseph Layshot

Master's Theses

On-board gimbal systems for camera stabilization in helicopters are typically based on linear models. Such models, however, are inaccurate due to system nonlinearities and complexities. As an alternative approach, artificial neural networks can provide a more accurate model of the gimbal system based on their non-linear mapping and generalization capabilities.

This thesis investigates the applications of artificial neural networks to model the inertial characteristics (on the azimuth axis) of the inner gimbal in a gyro-stabilized multi-gimbal system. The neural network is trained with time-domain data obtained from gyro rate sensors of an actual camera system. The network performance is evaluated …

A 24ft/7.3m Parabolic Reflector Antenna Performance & Feed Design Analysis, Anthony Shelley

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science & Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Anthony Shelley on November 29, 2010.

Fault-Injection Experiment For The Statistical Characterization Of Faults In Avionics Communication System, Amy M. Yates

Electrical & Computer Engineering Theses & Dissertations

Since flight control systems perform safety-critical functions, it is important to understand the possible effects on the closed-loop dynamical system's performance caused by these faults. The purpose of this project is to design the software and hardware needed to add fault-injection and monitoring capabilities to ROBUS-2, a flight communication system. ROBUS-2 is the current version of the fault-tolerant computer communication system used by the Scalable Processor-Independent Design for Enhanced Reliability (SPIDER), a general-purpose fault-tolerant integrated modular architecture (IMA) developed at the NASA Langley Research Center. The major components of SPIDER include processing elements (PEs) to perform calculations, bus interface units …

Stochastic Optimal Control In Nonlinear Systems, Celestin Nkundineza

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Stochastic control is an important area of research in engineering systems that undergo disturbances. Controlling individual states in such systems is critical. The present investigation is concerned with the application of the stochastic optimal control strategy developed by To (2010) and its implementation as well as providing computed results of linear and nonlinear systems under stationary and nonstationary random excitations. In the strategy the feedback matrix is designed based on the achievement of the objectives for individual states in the system through the application of the Lyapunov equation for the system. Each diagonal element in the gain or associated gain …

Kalman Filtering With State Constraints: A Survey Of Linear And Nonlinear Algorithms, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

The Kalman filter is the minimum-variance state estimator for linear dynamic systems with Gaussian noise. Even if the noise is non-Gaussian, the Kalman filter is the best linear estimator. For nonlinear systems it is not possible, in general, to derive the optimal state estimator in closed form, but various modifications of the Kalman filter can be used to estimate the state. These modifications include the extended Kalman filter, the unscented Kalman filter, and the particle filter. Although the Kalman filter and its modifications are powerful tools for state estimation, we might have information about a system that the Kalman filter …

Scan Loss Pattern Synthesis For Adaptive Array Ground Stations, William C. Barott, Mary Ann Ingram, Paul G. Steffes

Publications

We present several techniques for maximizing the contact time between low Earth orbiting satellites (LEOs) and a ground station (GS). The GS comprises an adaptive array of electronically steered space-fed lenses (SFLs). Each SFL is manufactured as a low-cost printed circuit with the result that it exhibits scanning loss. By differently orienting the boresights of the SFLs in the adaptive array, the SFL's scanning losses can be made to optimally complement the path loss of the LEO, thereby reducing the cost of the GS while maximizing the download capacity of the satellite link. The optimization, implemented with a genetic algorithm …

Uav Pirates And Silentrack Integration, Travis Dean, Hushnak Singh, Ashley Wager, Matthew (Matt) Woolridge

Electrical Engineering

The integration of the UAV pirating system with the SilenTrack video tracking system will allow the combined system to automatically identify and track a suspicious air vehicle visually as well as identify and decode the RF control signal. Once a threat has been identified, the system will execute an algorithm to associate each control channel with the corresponding flight control surface. Once the control channels have been decoded the user can use a hand held radio controller to maneuver the drone which is now under their command.

Analytic Confusion Matrix Bounds For Fault Detection And Isolation Using A Sum-Of-Squared-Residuals Approach, Daniel J. Simon, Donald L. Simon

Electrical and Computer Engineering Faculty Publications

Given a system which can fail in 1 of n different ways, a fault detection and isolation (FDI) algorithm uses sensor data to determine which fault is the most likely to have occurred. The effectiveness of an FDI algorithm can be quantified by a confusion matrix, also called a diagnosis probability matrix, which indicates the probability that each fault is isolated given that each fault has occurred. Confusion matrices are often generated with simulation data, particularly for complex systems. In this paper, we perform FDI using sum-of-squared residuals (SSRs). We assume that the sensor residuals are s-independent and Gaussian, which …

Aircraft Data Collection System, Amy Kronsteiner, Danny Marx, Collin Heller, Nathaniel Garcia, Nicholas Riccobono, Scott Parks, Albert Liu

Biomedical Engineering

This report outlines the design and building process for an interchangeable testing device that collects aircraft performance data. Included is the project objectives, system requirements, management plan, design concept development, design details, manufacturing procedures, and project verification test plans. The device is a wing-mounted Pitot-static system integrated with an Electronic Flight Instrument System (EFIS).

Adverse Elevator Effect In Landing Flare, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Modeling And Analysis Of Low Earth Orbit Satellite And Ground Station Data Exchange Topology, Ersin Kocoglu

Mechanical & Aerospace Engineering Theses & Dissertations

In order to utilize space effectively, the primary function of satellite control in orbit around the Earth must be accomplished. This controlling process includes two main segments, ground stations serving as the controller units and orbiting satellites as the units to be controlled. This thesis explores a topological data exchange model that contains one satellite and multiple ground stations. The model is implemented in digital computer software. This model has multiple purposes and can be used to simulate satellite passes over ground stations and can also be used to predict communication time and the amount of transferred data. The model …

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 …

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 …

Aiding Gps With Additional Satellite Navigation Services, Yasin A. Mutlu

Theses and Dissertations

In modern warfare navigation services are very important. GPS is currently providing service for accurate navigation, except in some areas, especially urban areas, where GPS signals cannot always be tracked by users. In these cases some additional navigation support could be provided by other global navigation satellite systems. If GPS is combined with other navigation systems than the navigation gap will be minor. In this thesis, the effect of combining GPS with other satellite navigation systems, specifically GLONASS, Galileo and Compass, is evaluated in terms of availability and position dilution of precision (PDOP) values. First, satellite constellations are simulated in …

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 …

Constrained Kalman Filtering Via Density Function Truncation For Turbofan Engine Health Estimation, Daniel J. Simon, Donald L. Simon

Electrical and Computer Engineering Faculty Publications

Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This article develops an analytic method of incorporating state variable inequality constraints in the Kalman filter. The resultant filter truncates the probability density function (PDF) of the Kalman filter estimate at the known constraints and then computes the constrained …

Real-Time On-Board Object Tracking For Cooperative Flight Control, Ajay Kumar Mandava, Emma Regentova, Henry Selvaraj

Electrical & Computer Engineering Faculty Research

One of possible cooperative Situations for flights could be a scenario when the decision on a new path is taken by A Certain fleet member, who is called the leader. The update on the new path is Transmitted to the fleet members via communication That can be noisy. An optical sensor can be used as a back-up for re-estimating the path parameters based on visual information. For A Certain topology, the issue can be solved by continuous tracking of the leader of the fleet in the video sequence and re-adjusting parameters of the flight, accordingly. To solve such a problem …

Reinforcement-Learning-Based Output-Feedback Control Of Nonstrict Nonlinear Discrete-Time Systems With Application To Engine Emission Control, Peter Shih, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning-based output adaptive neural network (NN) controller, which is also referred to as the adaptive-critic NN controller, is developed to deliver the desired tracking performance for a class of nonlinear discrete-time systems expressed in nonstrict feedback form in the presence of bounded and unknown disturbances. The adaptive-critic NN controller consists of an observer, a critic, and two action NNs. The observer estimates the states and output, and the two action NNs provide virtual and actual control inputs to the nonlinear discrete-time system. The critic approximates a certain strategic utility function, and the action NNs minimize the strategic utility …

Aerodynamic Analysis Of An Urban Magnetic Levitation Vehicle, John Matthew Wells

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis will detail the aerodynamic qualities of a magnetic levitation concept vehicle designed to be installed on Old Dominion University's campus. The vehicle is representative of a class of small, low-speed Maglev systems commonly referred to as Urban Maglev. A 1:12 scale model underwent testing in Old Dominion's low speed wind tunnel. Force and moment coefficients were measured over a wide range of yaw angles. Results give insight into crosswind effects and how these forces affect vehicle dynamics. An analysis of this type is important in understanding the ride quality and safety of the system. Force Coefficients range from …

Dynamic Interaction Of Elevated Guideway With Uncontrolled Maglev Vehicles, Sumanth Reddy Velma

Mechanical & Aerospace Engineering Theses & Dissertations

A flexible guideway on an elevated foundation is a key to affordable maglev urban transit. The flexible guideway can undergo significant dynamic motion, either when a vehicle solely relies on an open-loop control system or when a vehicle equipped with feedback control system experiences failure, due to fluctuating magnetic forces between the vehicle and the guideway. In an attempt to understand the effect of the uncontrolled vehicle on the structural response of the guideway, its dynamic interaction with maglev vehicles is investigated under various operating conditions. To this end, two vehicle models using Electrodynamic suspension (EDS) and Electromagnetic suspension (EMS) …

The Navigation Potential Of Ground Feature Tracking, Guner Mutlu

Theses and Dissertations

This research effort examines the reduction of error in inertial navigation aided by vision. This is part of an effort focused on navigation in a GPS denied environment. The navigation concept examined here consists of two main steps. First, extract the position of a tracked ground object using vision and geo-locate it in 3 dimensional navigation frame. In this first step multiple positions of the UAV are assumed known; think of a synthetic aperture. The only information about the tracked ground objects/features is the unit vector that points to the objects from the center of the camera. Two such vectors …

Stability Analysis, Modeling, Simulation And Experimental Testing Of An Ems Maglev System With Structural Flexibility, Aravind M. Hanasoge

Mechanical & Aerospace Engineering Theses & Dissertations

Vehicle-guideway interaction studies of Magnetically Levitated (Maglev) vehicles indicate that structural flexibility can adversely affect the overall stability and performance of such systems. This is one of the reasons why guideways are generally made very rigid. This in turn leads to increased cost of the overall system since guideway construction forms a significant portion of the overall cost. In this dissertation, the influence of structural flexibility on the stability of Electromagnetic Suspension (EMS) Maglev systems is studied. It is shown how inherently unstable and flexible structure EMS Maglev systems can achieve guaranteed stability by using collocated actuators and sensors, along …

Multidisciplinary Design Optimization Of An Extreme Aspect Ratio Hale Uav, Bryan J. Morrisey

Master's Theses

ABSTRACT

Multidisciplinary Design Optimization of an Extreme Aspect Ratio HALE UAV

Bryan J. Morrisey

Development of High Altitude Long Endurance (HALE) aircraft systems is part of a vision for a low cost communications/surveillance capability. Applications of a multi payload aircraft operating for extended periods at stratospheric altitudes span military and civil genres and support battlefield operations, communications, atmospheric or agricultural monitoring, surveillance, and other disciplines that may currently require satellite-based infrastructure. Presently, several development efforts are underway in this field, including a project sponsored by DARPA that aims at producing an aircraft that can sustain flight for multiple years and …

A Pipeline Analog-To-Digital Converter For A Plasma Impedance Probe, Mohamad A. El Hamoui

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Space instrumentation technology is an essential tool for rocket and satellite research, and is expected to become popular in commercial and military operations in fields such as radar, imaging, and communications. These instruments are traditionally implemented on printed circuit boards using discrete general-purpose Analog-to-Digital Converter (ADC) devices and other components. A large circuit board is not convenient for use in micro-satellite deployments, where the total payload volume is limited to roughly one cubic foot. Because micro-satellites represent a fast growing trend in satellite research and development, there is motivation to explore miniaturized custom application-specific integrated circuit (ASIC) designs to reduce …

A Compact Lidar For Aircraft Ozone Atmospheric Measurements, Joel A. Marcia

Electrical & Computer Engineering Theses & Dissertations

Researchers and the general public have expressed great concern over how human activities exacerbate pollution's deteriorating impact upon the environment. Effects such as global warming, air quality and ozone layer depletion are but a few examples that can have a dramatic effect on the quality of life worldwide.

A compact lidar system for the purpose of aircraft ozone atmospheric measurements was tested and evaluated. This system will eventually be deployed for aircraft-based, and possibly unpiloted atmospheric vehicle (UAV), ozone and aerosol measurements to improve our understanding of ozone production and transport. Each of the major subsystems was characterized and from …

Shielding Effectiveness Of Superalloy, Aluminum, And Mumetal Shielding Tapes, Cindy Suit Cheung

Master's Theses

Using MIL-HDBK-419A, MATLAB and Nomographs, Shielding Effectiveness for the Magnetic Field, Electric Field, and Plane Wave were calculated over a frequency range from 10 Hz to 1 GHz. The three shielding tapes used included superalloy, aluminum, and mumetal. Calculations for Shielding Effectiveness involve the computation of Absorption Loss, Reflection Loss, and Re-Reflection Correction Factor. From the outcome of the calculations, it was suitable to conclude that all three metals fulfill the 40 dB Shielding Effectiveness requirements for SGEMP fields for frequencies greater or equal to 1 MHz. Accordingly, all three shielding tapes provide at least 40 dB of shielding to …

Failure Detection Of A Pseudolite-Based Reference System Using Residual Monitoring, Michael A. Ciampa

Theses and Dissertations

The 746th TS uses a flight reference system referred to as the Central Inertial and GPS Test Facility (CIGTF) Reference System (CRS). Currently the CRS is the modern standard flight reference system for navigation testing, but high accuracy is dependent on the availability of GPS. A pseudolite system is currently being developed to augment the CRS and supply the capability to maintain high accuracy navigation under normal and jamming conditions. Pseudolite measurements typically contain cycle slips and other errors (such as multipath, tropospheric error, measurement noise) that can affect reliability. Past work relied on the receiver-reported signal-to-noise (SNR) value to …

Fusion Of Inertial Sensors And Orthogonal Frequency Division Multiplexed (Ofdm) Signals Of Opportunity For Unassisted Navigation, Jason G. Crosby

Theses and Dissertations

The advent of the global positioning system (GPS) has provided worldwide high-accuracy position measurements. However, GPS may be rendered unavailable by jamming, disruption of satellites, or simply by signal shadowing in urban environments. Thus, this thesis considers fusion of Inertial Navigation Systems (INS) and Orthogonal Frequency Division Multiplexed (OFDM) signals of opportunity (SOOP) for navigation. Typical signal of opportunity navigation involves the use of a reference receiver and uses time difference of arrival (TDOA) measurements. However, by exploiting the block structure of OFDM communication signals, the need for the reference receiver is reduced or possibly removed entirely. This research uses …

Characterizing The Exhaust Plume Of The Three-Electrode Micro Pulsed Plasma Thrusters, Myeongkyo Seo

Theses and Dissertations

Three-electrode micro-PPTs are a new version of two electrode micro-PPTs devices. Performance predictions and contamination expectations are essential characteristics needed by satellite designers. In order to focus on thruster specific impulse, thrust and efficiency, measuring the exhaust velocity or impulse bit and propellant consumption rate is essential. While this is not always possible to measure directly, focusing on the ejected mass from the PPT provides significant information allowing determination of these performance statistics. Specifically, focusing on exhaust angle distribution and velocity of the exhaust particles is the emphasis of this work. The results show that the three-electrode micro-PPT is more …