Aerospace Engineering Commons^™

Optimal Placement Of Artificial Hair-Cell Airflow Sensors For Bioinspired Flight-By-Feel, Alex C. Hollenbeck

Theses and Dissertations

The Sparse Sensor Placement Optimization for Prediction (SSPOP) algorithm reduces highdimensional airflow data to a low-dimensional sparse approximation to identify an optimal placement for any number of sensors on airfoil or wing models of arbitrary shape and size, and outperforms conventional optimization techniques in accuracy and speed. For 2D flow this algorithm found a sensor placement solution (design point, or DP) which predicts AoA to within 0.10 degrees and ranks within the top 1 percent of the design space. On 3D wing models SSPOP found four-sensor DPs ranked well within the top 0.10 percent. Experimental validation with velocity and pressure …

A Review Of Avian-Inspired Morphing For Uav Flight Control, Christina Harvey, Lawren L. Gamble, Christian R. Bolander, Douglas F. Hunsaker, James J. Joo, Daniel J. Inman

Mechanical and Aerospace Engineering Faculty Publications

The impressive maneuverability demonstrated by birds has so far eluded comparably sized uncrewed aerial vehicles (UAVs). Modern studies have shown that birds’ ability to change the shape of their wings and tail in flight, known as morphing, allows birds to actively control their longitudinal and lateral flight characteristics. These advances in our understanding of avian flight paired with advances in UAV manufacturing capabilities and applications has, in part, led to a growing field of researchers studying and developing avian-inspired morphing aircraft. Because avian-inspired morphing bridges at least two distinct fields (biology and engineering), it becomes challenging to compare and contrast …

Model Predictive Control Synthesis For The Innovative Control Effector Tailless Fighter Aircraft, Christopher Proctor

Masters Theses

A nonlinear model predictive control law was developed for the Lockheed Martin Innovative Control Effector tailless fighter aircraft to track way points. In general, aircraft are described by nonlinear dynamics that are dependent on the regime of flight. Additionally strict requirements on state and actuator constraints are common to all aircraft. Tailless aircraft are usually overdetermined systems, meaning solutions to control problems are not unique, and the system is non-affine. The proposed nonlinear control law considers those constraints during run-time, and solves the nonlinear control problem for a range of points within different flight regimes. The control law was developed …

Learn-To-Fly Control System Design, Alexander Brent Streit

Electrical & Computer Engineering Theses & Dissertations

In order to improve aircraft flight control system development life cycle, new flight control techniques are being explored to allow the system to ``learn-to-fly" with limited a priori information of the aircraft's aerodynamic characteristics. One approach is to have a system identification process operating on-the-fly to generate mathematical models which can be used to update control laws. In this thesis, a wind tunnel experiment was conducted with a model aircraft set up to be free-to-roll, so system identification and control methods could be explored for a one-degree-of-freedom case. In particular this thesis covers the design of a novel control system …

Design Of Flight Control Laws For A Novel Stratospheric Dual-Aircraft Platform, Cindy Nshuti

Doctoral Dissertations and Master's Theses

Dual-aircraft platform (DAP) is a novel concept that features two glider-like unmanned aerial systems (UAS) tethered via a thin adjustable cable allowing them to sail back-and-forth, without propulsion, using vertical wind shear. DAP offers the potential of a low-cost atmospheric satellite. This thesis presents the results of an initiative to demonstrate this novel flight concept through modeling, simulation, and flight testing at Embry-Riddle Aeronautical University (ERAU). A realistic simulation environment, described herein, was developed to support the development and testing of flight control systems. This environment includes nonlinear aerodynamic models for the aircraft, a multi-element cable dynamics model, propeller-motor thrust …

Formation Flight For Fuel Saving In Coronet Missions Of Kc-135r And F-15c/E, Christopher Allen Kniffin

Mechanical and Aerospace Engineering Theses - Archive

The fuel saving benefit of formation flight has been demonstrated through theoretical and computational analyses, simulation, wind tunnel and flight tests. When an aircraft flies in a specific region in the wake of another aircraft, it experiences upwash, which results in reduced drag and thus reduced thrust requirement. One specific USAF mission that can potentially benefit from formation flight is coronet missions. In a coronet mission, fighter aircraft are escorted and refueled, as needed, by tanker aircraft over a long range. During the flight, the receiver aircraft fly in formation with the tanker but outside of the wake of the …

Performance Analysis, Dynamic Simulation And Control Of Mass-Actuated Airplane, Sukru Akif Erturk

Mechanical and Aerospace Engineering Dissertations - Archive

The control of space, aerial and underwater vehicles requires moment generation mechanisms to change their orientation. In addition to or in place of conventional moment generation actuators, internally moving-mass actuation has been proposed and/or used for such vehicles. The primary principle for mass-actuation is to reposition gravitational force to change the associated moment while the secondary effect may come from the inertial force due to the motion of the masses. Recent development/miniaturization in flight control sensor, computing and actuation, and electric motors and expansion of applications for small UAV (Unmanned Aerial Vehicle) offer a potential for implementation of internal mass-actuation …

Design Of Synthetic Jet Actuator For Flight Control Of Small Uav, Priyanka Pagadala

Doctoral Dissertations and Master's Theses

The main idea of this project is to develop a prototype SJA - Synthetic Jet Actuator to embed into a small UAV with modified Glauert wing cross-section for Active Flow Control. Apart from lift enhancement, drag reduction, or separation control, etc; LCO suppression might be possible by modifying the boundary layer through the use of these actuators. For initial investigation, a wing section with span of 12.4 cm and chord of 14 cm was fabricated and tests were conducted in the subsonic wind tunnel at the free stream velocities of 5 and 10 m / s. From these experiments, lift …

Control Design And Performance Analysis For Autonomous Formation Flight Experiments, Caleb M. Rice

Graduate Theses, Dissertations, and Problem Reports (ETD)

Autonomous Formation Flight is a key approach for reducing greenhouse gas emissions and managing traffic in future high density airspace. Unmanned Aerial Vehicles (UAV’s) have made it possible for the physical demonstration and validation of autonomous formation flight concepts inexpensively and eliminates the flight risk to human pilots. This thesis discusses the design, implementation, and flight testing of three different formation flight control methods, Proportional Integral and Derivative (PID); Fuzzy Logic (FL); and NonLinear Dynamic Inversion (NLDI), and their respective performance behavior. Experimental results show achievable autonomous formation flight and performance quality with a pair of low-cost unmanned research fixed …

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 …

An Investigation Into The Feasibility Of Using A Modern Gravity Gradient Instrument For Passive Aircraft Navigation And Terrain Avoidance, Marshall M. Rogers

Theses and Dissertations

Recently, Gravity Gradient Instruments (GGIs) - devices which measure the spatial derivatives of gravity, have improved remarkably due to development of accelerometer technologies. Specialized GGIs are currently flown on aircraft for geological purposes in the mining industries. As such, gravity gradient data is recorded in flight and detailed gradient maps are created after post mission processing. These maps, if stored in a database onboard an aircraft and combined with a GGI, form the basis for a covert navigation system using a map matching process. This system is completely passive and essentially unjammable. To determine feasibility of this method, a GGI …

Multivariable Flight Control Design Tool Incorporating Gain And Phase Root Locus, Yong Ki Yoon

Mechanical & Aerospace Engineering Theses & Dissertations

A challenging problem in flight control system design for highly maneuverable aircraft is the coordinated control of the lateral-directional axes. Design goals are based on desired flying qualities giving an indication of whether the response to pilot inputs will be acceptable. Satisfying these closed-loop design objectives employing a computerized flight control system requires multiple feedback and crossfeed paths which operate in a well coordinated fashion. Contemporary control design tools, which close all loops simultaneously, have addressed this problem for several decades. Concerns associated with these strategies are the complicated mathematical relationships between the designer inputs and resulting closed-loop properties, and …

Velocity Estimate Following Air Data System Failure, Scott A. Mclaren

Theses and Dissertations

Modern high performance aircraft can provide amazing performance due in part to their advanced flight control systems that require gain scheduling to provide optimum performance over a huge flight envelope. In modern fighter aircraft, this gain scheduling is a function of airspeed, and almost all of the research involving aircraft gain scheduling assumes aircraft airspeed to be a known quantity. The purpose of this research was to investigate a method of determining an aircraft’s airspeed in the event of total air data system failure. The process began by combining known aircraft information following an air data system failure to determine …

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 …

Development Of A Low-Latency, High Data Rate, Differential Gps Relative Positioning System For Uav Formation Flight Control, Stephen J. Comstock

Theses and Dissertations

In order for Unmanned Aerial Vehicles (UAVs) to be able to fly missions currently performed by manned aircraft, they must be able to conduct in-flight refueling. Additionally, significant fuel savings can be realized if multiple UAV's are able to fly in precise formation and align wingtip vortices. In either case, the precise relative position between the aircraft must be known to an accuracy of only a few centimeters. Previous research at the Air Force Institute of Technology culminated in the development of a relative positioning system for manned aircraft. This thesis presents the development of the next-generation system designed for …

Performance Analysis Of Recoverable Flight Control Systems Subject To Neutron-Induced Upsets Using Hybrid Dynamical Models, Hong Zhang

Electrical & Computer Engineering Theses & Dissertations

It has been observed that atmospheric neutrons can produce single-event upsets in digital flight control hardware. Potentially, they can reduce system performance and introduce a safety hazard. One experimental system-level approach investigated to help mitigate the effects of these upsets is NASA Langley's Recoverable Computer System. It employs rollback error recovery using dual-lock-step processors together with new fault tolerant architectures and communication subsystems.

In this dissertation, a class of stochastic hybrid dynamical models, which consists of a jump-linear system and a stochastic finite-state automaton, is used to describe the performance of a Boeing 737 aircraft system in closed-loop with a …

A Markovian Statistical Analysis Of Single-Event Upsets On Closed-Loop Flight Control Systems, Anushka Vishnukumar Lakdawaia

Electrical & Computer Engineering Theses & Dissertations

The operation of aircrafts depend heavily on closed-loop digital flight control systems which can be disrupted or upset by errant neutrons at aircraft flight altitudes. These upsets, called single-event upsets, range from data corruption to short circuits which can potentially cause physical damage to digital devices and unexpected behaviors in flight controls. Experiments conducted at the Los Alamos Neutron Science Center consisted of irradiating an experimental flight control computer (FCC) architecture with a high intensity neutron beam while the FCC controlled a simulation of a Boeing 737. It was postulated that the upset statistics on the FCC could be fitted …

Formation Flight Control For Aerial Refueling, Steven M. Ross

Theses and Dissertations

A controller is designed for an aircraft to autonomously fly formation during aerial refueling. Requirements for a refueling autopilot are stated. A six-degree-of-freedom model is developed for an F-16 lead aircraft and a Learjet LJ-25 wing aircraft. Bare airframe stability of both aircraft is investigated, and stability augmentation is performed. A Matlab Simulink® simulation is built to reproduce the sensor inputs that will be available to the wing aircraft in flight, including disturbances. Control frames are investigated to determine the optimum presentation of the error vector for control during the task of air refueling. Control laws are developed from the …

Contemporary-Classical Sequential Loop Design With Parameter Uncertainty, Donghyuk Jeong

Mechanical & Aerospace Engineering Theses & Dissertations

Standard sequential loop closure design based on Evans root migration concepts is a well accepted, insightful and effective technique for meeting nominal performance objectives and traditional gain-phase stability margin requirements. Unfortunately, assessment of closed-loop variations resulting from parameter error is a post-process, implying an undesirable design-assess-redesign procedure is necessary if variations are found unacceptable. Further, the modem parameter uncertainty assessment framework is often inconsistent, both quantitatively and qualitatively, with the redesign task. Specifically, the parameter uncertainty assessment variables are not readily apparent in the sequential loop design framework, and these variables provide little guidance for the redesign strategy. Therefore, enhancing …

Nonlinear Regression Methods For Estimation, Eric B. Nelson

Theses and Dissertations

Regression techniques are developed for batch estimation and applied to three specific areas, namely, ballistic trajectory launch point estimation, adaptive flight control, and radio-frequency target triangulation. Specifically, linear regression with an intercept is considered in detail. An augmentation formulation is developed. Extensions of theory are applied to nonlinear regression as well. The intercept parameter estimate within the linear regression is used to identify the effects of trim change that are associated with the occurrence of a control surface failure. These estimates are used to adjust the inner loop control gains via a feed-forward command, hence providing an automatic reconfigurable retrim …

Characterization Of A Rotary Flat Tail As A Spoiler And Parametric Analysis Of Improving Directional Stability In A Portable Uav, Troy A. Leveron

Theses and Dissertations

The United States Air Force Research Lab, Munitions Directorate, Flight Vehicles, Integration Branch (AFRL/MNAV), has developed a flexible wing micro air vehicle (MAV) to be used with special tactics groups. In keeping with the requirement that this MAV be compact, previous research developed a rotatable tail mechanism which resulted in tail movement similar to that of a bird's tail. In this study the design of this tail was modified to produce a more storable vehicle. The redesign also allowed the tail to deflect upward to large angles, enabling the tail to be used as a spoiler. The aerodynamic effects of …

Full Capability Formation Flight Control, Ryan K. Osteroos

Theses and Dissertations

The subject of automatic formation flight control is of current interest to the development of Unmanned Aerial Vehicles (UAV). Previous control approaches have been refined in this work to allow more robust maneuvering and to include a fourth control parameter. The equations of motion for each aircraft as a point mass, expressed in a wind-axis coordinate system, are coupled into differential equations that model the two aircraft system dynamics. Control laws are developed that include proportional and integral action. Gains are determined based on formation performance. Lead maneuvers are simulated and the controller is gauged on its ability to maintain …

Prediction Of Rigid Body Aircraft Acceleration Response Due To Atmospheric Disturbances, Billy Keith Buck

Mechanical & Aerospace Engineering Theses & Dissertations

Methodology to predict aircraft transient motion resulting from flight within an unsteady atmospheric environment, coupled with validation using flight test data is proposed. A family of five linear dynamic models is developed for describing the normal acceleration throughout an aircraft cabin due to vertical gust excitation. The five models successively build upon each other by incorporating higher fidelity gust penetration effects while simultaneously maintaining a unified modeling framework. Six wind fields reconstructed from flight test data are used to excite the vehicle models. Simulation responses are compared with forward, center, and aft accelerometer response data recorded during the test. Each …

Experimental Investigation Into The Aerodynamic Performance Of Both Rigid And Flexible Wing Structured Micro-Air-Vehicles, Anthony M. Deluca

Theses and Dissertations

The Air Force Research Lab, Munitions Directorate, Eglin Air Force Base, Florida has designed a man-portable carbon-fiber Micro-Air-Vehicle (MA V) used for on-the-spot surveillance by Special Operations Forces (SOF) for enemy reconnaissance as well as post-strike Battle Damage Assessment (BDA).The main goals of this experiment are: 1) characterize the flow quality of the new AFIT 3' x 3' wind tunnel and 2) determine the aerodynamic performance characteristics of the 24" span, 6" chord flexible and rigid wing MA V s. The turbulent intensity of the wind tunnel was approximately 2%. Both MA Vs had an average lift slope within 3.5% …

Outside Loop Control In Asymmetrical Trimmed Flight Conditions, Gary D. Miller

Theses and Dissertations

Traditionally flight control systems have used linearized equations of motion solved around a single trim point. This thesis proposes a nested-loop controller directly solved from the equations of motion. The control equations were developed as a solution to asymmetrically trimmed flight conditions. A two-loop design was proposed for the controller. The outer loop modeled the aircraft as a point mass and all forces were balanced to find the aircraft states. The equations input the control variables and output the aircraft states. The inner-loop utilizes the six-degree of freedom model of the aircraft to solve the moment equations. With the input …

A Comparison Of Nonlinear Algorithms To Prevent Pilot-Induced Oscillations Caused By Actuator Rate Limiting, James G. Hanley

Theses and Dissertations

The objective of this study was to compare the ability of the Feedback-with-Bypass (FWB) and the Derivative-Switching (DS) flight control system filters to prevent PIO during actuator rate limiting, and the filters' effects on aircraft handling qualities. This comparison was conducted in three steps: computer simulation, ground simulation in the Large Amplitude Multimode Aerospace Research Simulator (LAMARS), and flight tests conducted in the Variable Stability In-flight Simulator Test Aircraft (VISTA). During computer simulation, the FWB filter better reduced the phase lag and prevented sustained or divergent oscillations during the closed-loop analysis. During both ground simulation and flight tests, the FWB …

Analysis Of Error Recovery Effects On Digital Flight Control Systems, Arturo Tejada Ruiz

Electrical & Computer Engineering Theses & Dissertations

Life-critical, real-time applications like flight-by-wire aircraft, rely on closed-loop digital control systems and fault-tolerant computer systems to reliably achieve the desired operation. The computer systems, however, may be affected by random hardware/software faults induced mainly by environmental conditions such as high intensity radiated fields (HIRF) and lightning. These harsh electromagnetic environments are known to induce common­ mode faults (CMF) in aircraft electronic systems, which disrupt fault-tolerant provisions and possibly affect the operation of the digital control system. Current flight-by-wire aircraft have computer systems that can neither detect CMF nor recover from them. New systems are under investigation that can recover …

Flight Control Failure Detection And Control Redistribution Using Multiple Model Adaptive Estimation With Filter Spawning, Michael L. Torres Jr.

Theses and Dissertations

In the current research, the MMAE with Filter Spawning and Control Redistribution (MMAE/FS/CR) are used together to identify failures and apply appropriate corrections. This effort explores the performance of the MMAE/FS/CR in different regions of the flight envelope using model and gain scheduling. The MMAE/FS/CR is able to detect complete and partial actuator/surface failures, as well as complete sensor failures. Once the actuator/surface failure is identified and the effectiveness is determined in the case of partial failures, proper control is applied in order to accomplish the desired pilot command. Improvements in the algorithm are required in order to enhance the …

Optimal Aeroelastic Vehicle Sensor Placement For Root Migration Flight Control Applications, Abdul Ghafoor Al-Shenhabi

Mechanical & Aerospace Engineering Theses & Dissertations

An important step in control design for elastic systems is the determination of the number and location of control system components, namely sensors. The number and placement of sensors can be critical to the robust functioning of active control systems, especially when the system of interest is a large high-speed aeroelastic vehicle. The position of the sensors affects not only system stability, but also the performance of the closed-loop system. In this dissertation, a new approach for sensor placement in the integrated rigid and vibrational control of flexible aircraft structures is developed. Traditional rigid-body augmentation objectives are addressed indirectly through …

Three Dimensional Formation Flight Control, James K. Hall

Theses and Dissertations

Automating the control of an aircraft flying in formation necessitates the extension of the theory of formation flight control to allow for three dimensional maneuvers. The formation was modeled as a two-aircraft, leader and wingspan, formation. Both aircraft has its own three dimensional, rotating and translating, Cartesian axes system, with special attention being given to the motion of the leader in relation to the wingspan. The controller operated using the equations of motion expressed in the rotating reference frame of the wing aircraft. The control system has seven states, three inputs and three disturbance signals to model the dynamics of …