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Articles 1 - 27 of 27
Full-Text Articles in Controls and Control Theory
An Analytic Study Of Pursuit Strategies, Mark E. Vlassakis
An Analytic Study Of Pursuit Strategies, Mark E. Vlassakis
Theses and Dissertations
The Two-on-One pursuit-evasion differential game is revisited where the holonomic players have equal speed, and the two pursuers are endowed with a circular capture range ℓ > 0. Then, the case where the pursuers' capture ranges are unequal, ℓ1 > ℓ2 ≥ 0, is analyzed. In both cases, the state space region where capture is guaranteed is delineated and the optimal feedback strategies are synthesized. Next, pure pursuit is considered whereupon the terminal separation between a pursuer and an equal-speed evader less than the pursuer's capture range ℓ > 0. The case with two pursuers employing pure pursuit is considered, and …
Active Control Of A Morphing Wing Aircraft And Failure Analysis For System Reliability, Madison J. Montgomery
Active Control Of A Morphing Wing Aircraft And Failure Analysis For System Reliability, Madison J. Montgomery
Theses and Dissertations
A morphing wing aircraft has the ability to increase the efficiency of an aircraft by better optimizing lift and drag characteristics during a flight. A morphing wing UAV was designed and constructed by AFRL/RQVS and required a means of control and method of characterizing the performance of the aircraft through flight testing. This research presents the design and construction of a control system capable of adjusting the morphing wing shape based on pilot commands and current flight status. The control system was tested and improved following a flight test crash utilizing failure mode analysis.
Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse
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 …
Model-Based Control Using Model And Mechanization Fusion Techniques For Image-Aided Navigation, Constance D. Hendrix
Model-Based Control Using Model And Mechanization Fusion Techniques For Image-Aided Navigation, Constance D. Hendrix
Theses and Dissertations
Unmanned aerial vehicles are no longer used for just reconnaissance. Current requirements call for smaller autonomous vehicles that replace the human in high-risk activities. Many times these activities are performed in GPS-degraded environments. Without GPS providing today's most accurate navigation solution, autonomous navigation in tight areas is more difficult. Today, image-aided navigation is used and other methods are explored to more accurately navigate in such areas (e.g., indoors). This thesis explores the use of inertial measurements and navigation solution updates using cameras with a model-based Linear Quadratic Gaussian controller. To demonstrate the methods behind this research, the controller will provide …
Nonlinear Regression Methods For Estimation, Eric B. Nelson
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 …
Swarming Reconnaissance Using Unmanned Aerial Vehicles In A Parallel Discrete Event Simulation, Joshua J. Corner
Swarming Reconnaissance Using Unmanned Aerial Vehicles In A Parallel Discrete Event Simulation, Joshua J. Corner
Theses and Dissertations
Current military affairs indicate that future military warfare requires safer, more accurate, and more fault-tolerant weapons systems. Unmanned Aerial Vehicles (UAV) are one answer to this military requirement. Technology in the UAV arena is moving toward smaller and more capable systems and is becoming available at a fraction of the cost. Exploiting the advances in these miniaturized flying vehicles is the aim of this research. How are the UAVs employed for the future military? The concept of operations for a micro-UAV system is adopted from nature from the appearance of flocking birds, movement of a school of fish, and swarming …
Adaptive And Reconfigurable Flight Control, Yih Shiun Huang
Adaptive And Reconfigurable Flight Control, Yih Shiun Huang
Theses and Dissertations
An indirect adaptive and reconfigurable flight control system is developed. The three-module controller consists of: (1) a system identification module, (2) a parameter estimate smoother, and (3) a proportional and integral compensator for tracking control. Specifically: (1) The identification of a linear discrete-time control system's open-loop gain is addressed. The classical Kalman filter theory for linear control systems is extended and the control system's state and loop gain are jointly estimated on-line. Explicit formulae for the loop gain's estimate and estimation error covariance are derived. The estimate is unbiased and the predicted covariance is reliable. (2) An adaptive smoother is …
Phugoid Damping Control, Nicolas J. Schindeler
Phugoid Damping Control, Nicolas J. Schindeler
Theses and Dissertations
A novel phugoid damping control design methodology is developed, based on the use of wind axes and a point-mass aircraft model. The state variables are air speed, flight path angle, and heading angle, the control variables are thrust setting, angle of attack, bank angle, and sideslip angle, and the command signals are airspeed, flight path angle, and heading angle or heading rate. All the variables and parameters are nondimensionalized. A multivariable set point controller is developed which consists of: (1) a trim calculation-based nonlinear feed-forward control computer; thus, given a commanded new trim state (air speed, flight path angle, and …
Design Of Flight Control Laws For Aircraft With Flexible Wings Using Quantitative Feedback Theory, Christina L. Osmon
Design Of Flight Control Laws For Aircraft With Flexible Wings Using Quantitative Feedback Theory, Christina L. Osmon
Theses and Dissertations
Aircraft composed of lightweight composite materials are extremely enticing since their structural weight is greatly reduced. However, the control of these aircraft is complicated by the resultant flexibility of the wings. Two avenues of approach are possible; stiffen the wings thus losing some of the weight reduction benefits, or design the lateral/directional flight control system cognizant of the wing's flexibility. In this thesis the second approach is taken. The design of three lateral/directional flight control systems for the sub-sonic flight envelope of the F-18 is presented. The Quantitative Feedback Theory (QFT) robust control design technique is used. These designs incorporate …
Multiple Model Adaptive Control Of The Vista F-16, Michael J. Stepaniak
Multiple Model Adaptive Control Of The Vista F-16, Michael J. Stepaniak
Theses and Dissertations
Multiple model adaptive control (MMAC) is investigated using the high-fidelity, nonlinear, six-degree-of-freedom Simulation Rapid-Prototyping Facility VISTA F-16. Detection of single actuator and sensor failures is considered, with an MMAC algorithm initially pursued which allows a controller specifically designed for each particular failure condition to replace the standard F-16 Block 40 flight control system (FCS) once the failure is detected. The synthesis of certain discrete-time LQG/PI controllers (those using control variables linearly dependent on state derivatives) is shown to be unattainable due to numerical difficulties. A novel control technique, termed control redistribution, is introduced which redistributes control commands (that would normally …
Applications Of ℓ1 And Mixed H2/ℓ1 Optimization, Mark S. Spillman
Applications Of ℓ1 And Mixed H2/ℓ1 Optimization, Mark S. Spillman
Theses and Dissertations
This thesis explores the use of ℓ1 and mixed H2/ℓ1 optimization methods to design flight control systems. ℓ1 optimization is used to handle tracking issues in the design of digital compensators. Control deflection and rate limitations, overshoot and undershoot limitations and steady-state error requirements are discussed. Model-matching techniques which produce acceptable tracking results with lower order controllers are also examined. New numerical methods for continuous H2/L1 and discrete H2/ℓ1 optimization are presented. These methods are used to design an aircraft controller in continuous and discrete time and the results are compared.
Improved Numerical Solution Of Mixed H2/H∞ Optimization With Applications, Linda D. Smith
Improved Numerical Solution Of Mixed H2/H∞ Optimization With Applications, Linda D. Smith
Theses and Dissertations
This study improved the numerical optimization technique used to compute mixed H2/H∞ controllers. The run time to generate the full curve of an H2/H∞ design was reduced by a factor of almost 200 for a specific example. This was accomplished by improving gradient calculations, upgrading the H∞ norm calculation to capture multiple peaks in the singular value plot and using routines that minimized processing time. The optimization routine used was the MATLAB CONSTR' Sequential Quadratic Programming (SQP) routine. This SQP routine was compared to a FORTRAN SQP numerical optimizer, IMSL-DNCONG. The method was …
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr.
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr.
Theses and Dissertations
A moving bank multiple model adaptive estimator-controller (MMAE-MMAC), based on linear system, quadratic cost, and Gaussian noise (LQG) assumptions, is used to quell unwanted vibrations in a large flexible space structure. The structure, known as the SPace Integrated Controls Experiment, or SPICE, exists at Phillips Laboratory, Kirtland AFB, NM. The structure consists of a large platform and a smaller platform connected by a tripod of flexible legs. The purpose of the control system is to maintain a very precise line-of- sight vector through the center of the spacecraft. Kalman filtering, used to estimate the position and velocity of the bending …
A Gain Scheduling Optimization Method Using Genetic Algorithms, Robert C. Martin Iv
A Gain Scheduling Optimization Method Using Genetic Algorithms, Robert C. Martin Iv
Theses and Dissertations
Gain scheduling. the traditional method of providing adaptive control to a nonlinear system, has long been an ad hoc design process. Until recently; little theoretical guidance directed this practitioners' art. For this reason a systematic study of this design process and its potential for optimization has never been accomplished. Additionally, the nonlinearities and the large search space involved in gain scheduling also precluded such an optimization study. Traditionally, the gain scheduling process has been some variation of a linear interpolation between discrete design points. By using powerful non-traditional optimization tools such as genetic algorithms there are ways of improving this …
A Comparison Of The Neal-Smith And ΩSpΤΘ2, ΣSp, ΤΘ Flying Qualities Criteria, Brian A. Kish
A Comparison Of The Neal-Smith And ΩSpΤΘ2, ΣSp, ΤΘ Flying Qualities Criteria, Brian A. Kish
Theses and Dissertations
Aircraft pitch response is a vital element of piloted vehicle flying qualities. There has been controversy over both the form and the substance of the requirements for short-term pitch response. Currently, MIL-STD- 1797A offers six different methods for evaluating short-term pitch response. These six methods often give conflicting results. Two methods are analyzed in this thesis - the Neal-Smith criteria and the ωspΤθ2, ςsp, τθ criteria. Domains from both criteria are mapped into each other identifying regions of conflict and regions of agreement. Parametric studies are performed and evaluated for trends. Further, a …
Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker
Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker
Theses and Dissertations
This thesis examines the use of the mixed H2-Microns optimal control synthesis method in the design of a flight control system for the lateral-directional axes of the F-16 Variable Stability In-Flight Simulator Test Aircraft (VISTA). The method is designed to minimize the H2 norm (two-norm) for a given value of microns. This should provide adequate noise and disturbance rejection while maintaining robustness against several types of uncertainties in the system. This thesis finds that, for this problem, the two-norm is not an accurate representation of the outputs of interest. When the two-norm is broken up into its constituent parts an …
Mixed H2-H∞ Optimization With Multiple H Infinity Constraints, Julio C. Ullauri
Mixed H2-H∞ Optimization With Multiple H Infinity Constraints, Julio C. Ullauri
Theses and Dissertations
A general mixed H2/H∞ optimal control design with multiple H∞ constraints is developed and applied to two systems, one SISO and the other MIMO. The SISO design model is normal acceleration command following for the F- 16. This design constitutes the validation for the numerical method, for which boundaries between the H2 design and the H∞ constraints arc shown. The MIMO design consists of a longitudinal aircraft plant (short period and phugoid modes) with stable weights on the H2 and H∞ transfer functions, and is linear- time-invariant. The controller order is reduced …
Direct Reduced Order Mixed H2/H∞ Control For The Short Take-Off And Landing-Maneuver Technology Demonstrator (Stol-Mtd), William C. Reigelsperger Jr.
Direct Reduced Order Mixed H2/H∞ Control For The Short Take-Off And Landing-Maneuver Technology Demonstrator (Stol-Mtd), William C. Reigelsperger Jr.
Theses and Dissertations
One of the conclusions from the STOL/MTD program was the need for a multivariable method of designing controllers of low order. This research investigated that problem by studying reduced order mixed H2/H∞ control theory applied to the STOL Landing configuration which employs both thrust vectoring and the use of a canard. Model matching techniques were used to obtain responses that met handling qualities criteria and reduced pilot workload by decoupling pitch rate and velocity commands. The time responses were found through nonlinear simulation and showed that the full order designs did match the ideal models very well …
A Handling Qualities Investigation Of Conventional, Rate Command- Attitude Hold, And Attitude Command-Attitude Hold Response-Types In The Probe And Drogue Air Refueling Task, Michael J. Taschner
A Handling Qualities Investigation Of Conventional, Rate Command- Attitude Hold, And Attitude Command-Attitude Hold Response-Types In The Probe And Drogue Air Refueling Task, Michael J. Taschner
Theses and Dissertations
This investigation examines the suitability of conventional, rate command/attitude hold (RCAH), and attitude command attitude hold (ACAH) response-types for the probe and drogue air refueling task. Data from a 1974 Calspan handling qualities investigation involving conventional response-types in the probe and drogue air refueling task were analyzed using the Bandwidth and STI Dropback criterions. Flight control laws were developed to achieve twelve superaugmented and two conventional configurations. The NT-33A analog variable stability system was used to simulate a relaxed static stability fighter and the NT-33A programmable digital flight control computer simulated the desired response-types. The handling qualities of the fourteen …
Automation Of Formation Flight Control, Vincent P. Reyna
Automation Of Formation Flight Control, Vincent P. Reyna
Theses and Dissertations
The research contained in this thesis explores the concepts of Automated Formation Flight Control documented in three previous AFIT theses. The generic formation analyzed consists of a Leader and Wingman, with the Wingman referencing its maneuvers off of Leader maneuvers. Specifically, planar formation flight control concerning only heading and velocity changes is considered. Next, the vertical separation constraint is relaxed to allow wing maneuvers outside of the flight plane of the lead in order to minimize the energy expended by the wing in a maneuver. Analysis of the two forms of formation flight control investigated in this thesis reveals the …
Evaluation Of Moderate Angle Of Attack Roll Of A Dual Engine, Thrust Vectoring Aircraft Using Quantitative Feedback Theory, Kevin E. Boyum
Evaluation Of Moderate Angle Of Attack Roll Of A Dual Engine, Thrust Vectoring Aircraft Using Quantitative Feedback Theory, Kevin E. Boyum
Theses and Dissertations
This thesis develops an innovative approach to the design of a flight control system for performing the large-amplitude velocity vector roll maneuver at high angles of attack AOAs. A six degree of freedom aircraft model is developed from the fundamental nine-state equations of motion using a modified linearization technique. The MIMO multiple-input multiple-output Quantitative Feedback Theory QFT robust control design technique is then used to jointly address the system nonlinearities present in this maneuver and the changes in the system parameters due to changes in flight condition, treating them as structured uncertainty in the design of a three-axis rate-commanded control …
Design Of A Flight Controller For An Unmanned Research Vehicle With Control Surface Failures Using Quantitative Feedback Theory, Mark S. Keating
Design Of A Flight Controller For An Unmanned Research Vehicle With Control Surface Failures Using Quantitative Feedback Theory, Mark S. Keating
Theses and Dissertations
This thesis describes the application of the multiple-input multiple- output (MIMO) Quantitative Feedback Theory (QFT) design technique to the design of a digital flight control system for the Lambda Unmanned Research Vehicle (URV). The QFT technique allows the synthesis of a control system which is robust in the presence of structured plant uncertainties. Uncertainties considered in this design are the aircraft's plant variation within the flight envelope and the effects of damage to aircraft control surfaces. Mathematical models of control surface failure effects on aircraft dynamics are derived and used to modify an existing small perturbation model of the Lambda. …
Optimal Control Design Advantages Utilizing Two-Degree-Of-Freedom Controllers, Michael J. Stephens
Optimal Control Design Advantages Utilizing Two-Degree-Of-Freedom Controllers, Michael J. Stephens
Theses and Dissertations
The purpose of this study was to investigate and describe the differences between a one-degree-of-freedom (1-DOF) controller, in which a controller is placed in a single location in the control loop, and a two-degree- of-freedom (2-DOF) controller, in which two separate controllers are designed -- one in the feedback loop and the other as a prefilter in the forward loop. The approach involved summarizing the major rules governing loop shaping for performance and robustness in the 1-DOF case and then extending the concepts to the 2-DOF case. H2 optimization was utilized to perform several types of SISO examples and …
Analysis And Characteristics Of Compressor Stall Precursor Signals In Forward And Aft Swept High Speed Compressor, Bernard J. Frank
Analysis And Characteristics Of Compressor Stall Precursor Signals In Forward And Aft Swept High Speed Compressor, Bernard J. Frank
Theses and Dissertations
The stall characteristic of four single-stage transonic compressor rotors were investigated as they were throttled to stall. Forward-swept, backward-swept, and straight leading edge rotors were examined. Three methods of analysis (1) windowed power spectrum densities of pressure and spatial Fourier coefficients, (2) phase tracking analysis, and (3) system identification were used to identify the first appearance of modal waves and their accompanying frequencies in order to identify a stall warning time. A direct correlation between the amount of stall warning time and the shape of the compressor characteristic was found. Specifically, if the compressor characteristic had a significant period of …
Design Of A Subsonic Envelope Flight Control System For The Vista F-16 Using Quantitative Feedback Theory, Odell R. Reynolds
Design Of A Subsonic Envelope Flight Control System For The Vista F-16 Using Quantitative Feedback Theory, Odell R. Reynolds
Theses and Dissertations
A controlled plant's characteristics can vary widely throughout its operational envelope. This is a major problem in nominal plant-based control system design. Hence, gain scheduling is often used for full envelop design. In this paper, it is proposed to address the plant's variability using robust control design concepts. In particular, the frequency domain based Quantitative Feedback Theory Multiple-Input Multiple-Output robust control design method is employed for the synthesis of a full envelop flight control system for an F-16 derivative. Compensators for the aircraft's pitch and lateral directional channels are designed, and the designs are validated using linear simulations.
Neural Networks For Dynamic Flight Control, Ronald E. Setzer
Neural Networks For Dynamic Flight Control, Ronald E. Setzer
Theses and Dissertations
This thesis examines the application of artificial neural networks (NNs) to the problem of dynamic flight control. The specific application is the control of a flying model helicopter. The control interface is provided through a hardware and software test bed called the Fast Adaptive Maneuvering Experiment (FAME). The NN design approach uses two NNs: one trained as an emulator of the plant and the other trained to control the emulator. The emulator neural network is designed to reproduce the flight dynamics of the experimental plant. The controller is then designed to produce the appropriate control inputs to drive the emulator …
Exploring Qdes As A Tool For Determining Limits Of Achievable Performance In Aircraft Design, Mark F. Reidinger
Exploring Qdes As A Tool For Determining Limits Of Achievable Performance In Aircraft Design, Mark F. Reidinger
Theses and Dissertations
This thesis explores the usefulness of a computer aided control design software package called QDES in determining the limits of achievable aircraft performance as it relates to controller capability. Modern aircraft, particularly fighters, are being designed to be statically unstable to enhance their maneuverability and performance. It is possible that the aircraft, although physically capable of a certain level of performance due to its engine/ airframe combination, may be uncontrollable up to this level. This study sought to develop a methodology to use QDES to make a preliminary analysis of an aircraft design to determine if there exists a controller …