Open Access. Powered by Scholars. Published by Universities.®

Controls and Control Theory Commons™

Open Access. Powered by Scholars. Published by Universities.®

PDF

1994

Articles 1 - 16 of 16

Full-Text Articles in Controls and Control Theory

Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker Dec 1994

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 …

Go to article

Applications Of ℓ1 And Mixed H2/ℓ1 Optimization, Mark S. Spillman Dec 1994

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.

Go to article

Next Generation Real-Time Systems: Investigating The Potential Of Partial-Solution Tasks, Robert E. J. Caley Dec 1994

Next Generation Real-Time Systems: Investigating The Potential Of Partial-Solution Tasks, Robert E. J. Caley

Theses and Dissertations

While the cyclic executive and fixed-priority scheduling strategies have been sufficient to handle traditional real- time requirements. they are insufficient for dealing with the complexities of next-generation real-time systems. New methods of intelligent control must be developed for guaranteeing on-time task completion for real-time systems that are faced with unpredictable and dynamically changing requirements. Implementing real-time processes as partial-solution tasks is one technique that may be beneficial. This type of task. when combined with intelligent control, has the potential for increasing pre-runtime schedulability, system maintainability. and runtime robustness. This research investigates the benefits of partial-solution tasks by experimentally measuring the …

Go to article

Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr. Dec 1994

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 …

Go to article

Improved Numerical Solution Of Mixed H2/H∞ Optimization With Applications, Linda D. Smith Dec 1994

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 …

Go to article

A Quantitative Feedback Theory Fcs Design For The Subsonic Envelope Of The Vista F-16 Including Configuration Variation, Scott N. Phillips Dec 1994

A Quantitative Feedback Theory Fcs Design For The Subsonic Envelope Of The Vista F-16 Including Configuration Variation, Scott N. Phillips

Theses and Dissertations

An aircraft's response to control inputs varies widely throughout its flight envelope. The aircraft configuration also impacts control response through variations in center of gravity and moments of inertia. Designing a flight control system (FCS) to accommodate the full flight envelope and configuration set of an aircraft is clearly a complex undertaking. Quantitative feedback theory (QFT) is a design tool which enables the engineer to attack this task in an efficient way. Although QFT is a robust control design technique, it is an interactive algorithm allowing the engineer full control over compensator order and gain. In this research effort, a …

Go to article

A Comparison Of The Neal-Smith And ΩSpΤΘ2, ΣSp, ΤΘ Flying Qualities Criteria, Brian A. Kish Dec 1994

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 …

Go to article

A Gain Scheduling Optimization Method Using Genetic Algorithms, Robert C. Martin Iv Dec 1994

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 …

Go to article

Mixed H2-H∞ Optimization With Multiple H Infinity Constraints, Julio C. Ullauri Jun 1994

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 …

Go to article

H2 Optimal Control With H∞, Μ, And L1 Constraints, David E. Walker Jun 1994

H2 Optimal Control With H∞, Μ, And L1 Constraints, David E. Walker

Theses and Dissertations

H2 optimization with convex constraints is considered. The optimal order-free solution is shown to be unique through convex analysis. H∞ constraints with feedforward terms and singular constraints are also allowed. The optimal fixed-order solution is shown to have the same characteristics as a mixed problem with regular H∞ constraints. Furthermore, these results are shown to hold for controller orders as low as the optimal H2 order. A numerical method is developed based on analytical gradients which results in sub- and super-optimal fixed-order controllers. The problem is extended to include an upper bound on a mu constraint …

Go to article

Direct Reduced Order Mixed H2/H∞ Control For The Short Take-Off And Landing-Maneuver Technology Demonstrator (Stol-Mtd), William C. Reigelsperger Jr. Mar 1994

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 …

Go to article

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 Mar 1994

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 …

Go to article

Model Parameter And Time Delay Estimation Using Gradient Methods, Aidan O'Dwyer, John Ringwood Jan 1994

Model Parameter And Time Delay Estimation Using Gradient Methods, Aidan O'Dwyer, John Ringwood

Conference papers

A number of approaches have been proposed for parameter and time delay estimation of process models in single input, single output (SISO) control systems using gradient descent algorithms; some of these approaches involve the selection of a rational polynomial that is used to approximate time delay variations. This paper takes a generalised approach to the investigation of the most appropriate choice of the rational polynomial, and the gradient descent algorithm, to be used.

Go to article

Automation Of Formation Flight Control, Vincent P. Reyna Jan 1994

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 …

Go to article

A Frequency Domain Based Self-Tuning Pid Controller, John Ringwood, Aidan O'Dwyer Jan 1994

A Frequency Domain Based Self-Tuning Pid Controller, John Ringwood, Aidan O'Dwyer

Conference papers

Traditionally, both explicit and implicit self-tuning controllers have employed time domain techniques for the identification and tracking of plant and controller parameters. The use of the frequency domain provides concise information on the dynamics of the process which has led to its wide acceptance as a domain for controller design. This paper demonstrates a method employing recursive, on-line measurement of the process frequency response, with a straightforward calculation of PID controller parameters. The computational effort involved is comparable with that of a time domain technique.

Go to article

Logic Synthesis With High Testability For Cellular Arrays, Andisheh Sarabi Jan 1994

Logic Synthesis With High Testability For Cellular Arrays, Andisheh Sarabi

Dissertations and Theses

The new Field Programmable Gate Array (FPGA) technologies and their structures have opened up new approaches to logic design and synthesis. The main feature of an FPGA is an array of logic blocks surrounded by a programmable interconnection structure. Cellular FPGAs are a special class of FPGAs which are distinguished by their fine granularity and their emphasis on local cell interconnects. While these characteristics call for specialized synthesis tools, the availability of logic gates other than Boolean AND, OR and NOT in these architectures opens up new possibilities for synthesis. Among the possible realizations of Boolean functions, XOR logic is …

Go to article