Controls and Control Theory Commons^™

Model-Based Reasoning In The Detection Of Satellite Anomalies, Ralph W. Dries

Theses and Dissertations

Automatic fault detection and recovery would be a mandatory requirement for a satellite where some degree of autonomy is required. This thesis reviews some AI techniques used for the detection of satellite anomalies, and concludes that the model-based reasoning paradigm is best suited for automated on-board fault detection because it can cope with situations not necessarily programmed into the knowledge base. Using the Scheme language and its SCOOPS object oriented extension, development of software is described that models the pitch control channel in the attitude and velocity control subsystem of a typical geo-stationary communications satellite. This model is used by …

Automatic Flight Control System Design For An Unmanned Research Vehicle Using Discrete Quantitative Feedback Theory, David G. Wheaton

Theses and Dissertations

This thesis presents the application of non-minimum phase (NMP) w'- plane discrete MIMO (multiple-input-multiple-output) Quantitative Feedback Theory (QFT) to the design of a three-axis rate-commanded automatic flight control system for an unmanned research vehicle (URV). The URV model used has seven inputs and three outputs derived from the small-angle perturbation equations of motion. Plant parameter uncertainty consists of six flight conditions derived from variations in the aircraft center of gravity, airspeed, and gross weight. A weighting matrix delts is used to post-multiply the plants for blending the seven effector inputs into three effective rate-command inputs and resulting in an effective …

Comparison Of Digital Controllers Used In Magnetic Suspension And Balance Systems, William A. Kilgore

Mechanical & Aerospace Engineering Faculty Publications

Dynamic systems that were once controlled by analog circuits are now controlled by digital computers. Presented is a comparison of the digital controllers presently used with magnetic suspension and balance systems. The overall responses of the systems are compared using a computer simulation of the magnetic suspension and balance system and the digital controllers. The comparisons include responses to both simulated force and position inputs. A preferred digital controller is determined from the simulated responses.

Transient Stability Hierarchical Control In Multimachine Power Systems, A Rubbai, F. Eugenio Villaseca

Electrical and Computer Engineering Faculty Publications

The authors present the optimal transient stability control problem in a hierarchical structure for multimachine power systems. The two-level structure retains the local closed-loop controls, thereby easing its implementation on existing systems. The formulation accounts for nonlinearities and interconnections, and the optimization of the system transient performance is obtained with less computational effort. Since the computations are distributed among the many local feedback subsystems, the storage and solution times are considerably less than those required by a single overall centralized controller. This advantage becomes much stronger as the system size increases. For illustration purposes, this technique was applied successfully to …

Study Of Direct Semiconductor Materials For An Optically Controlled Switch, Sung Taek Ko

Electrical & Computer Engineering Theses & Dissertations

A model for a bulk GaAs photoconductive switch has been developed and solved to determine the performance of the device in closing and opening switch applications. The GaAs material has been characterized by deep level transient spectroscopy (DLTS). Two electron traps (EL2 and EL5) and one hole trap (Cu_B} have been detected and were included in the model. Simulation studies are performed on several GaAs switch systems composed of different combinations and density of deep levels to investigate the influence of deep traps in a photoconductive switch system. The electron occupancy of each deep trap is traced in …

Design Of Multivariable Feedback Control Systems Via Spectral Assignment, Mohsen Marefat

Electrical & Computer Engineering Theses & Dissertations

During the past 15 year s significant advances have been made towards developing viable synthesis- techniques for multivariable feedback control systems. The entire aggregate of this theoretical work has been reviewed and consolidated. Diverse notations have been standardized into a single system. A two-step design philosophy for spectral assignment has been developed which first meets stability and time response requirements by assigning eigenvalues and eigenvector s and then provides for attainment of secondary objectives without significant deviation from the initial assignment. Finally, a computer-aided design package has been created to streamline the process of mathematical calculation and to allow users …

Electronic Control Of Electric Motors, Armando Castillo

Graduate Research Papers

The purpose of this study was to investigate the theoretical information on electronic control of electric motors as well as the current state-of-the-art on this topic. It was also intended to carry out some of the experimental circuits discussed, for future instructional situations.

Study Of Longitudinal Landing Flying Qualities Evaluation Using Pilot Model Theory, Eric D. Didomenico

Theses and Dissertations

Control Anticipation Parameter (CAP), used in MIL-SPEC-8785C as a longitudinal handling qualities criterion does not adequately distinguish between different flight phases. Recent flight test data from the Landing Approach Higher Order Systems (LAHOS) study further indicate the inadequacy of the second order approximations for higher order longitudinal landing flying qualities. Nine Aircraft that fall within the Level 1 boundary reveal pilot ratings ranging from 1.5 to 10 (Cooper/Harper). These nine aircraft are studied by combining their longitudinal dynamics with pilot modelling to examine a better method of landing flying quality prediction and evaluation. Pilot model theory (cross-over pilot model) is …

Design Of Multivariable Feedback Control Systems Via Spectral Assignment Using Reduced-Order Models And Reduced-Order Observers, Preston Ivanhoe Carraway Iii

Electrical & Computer Engineering Theses & Dissertations

The feasibility of using reduced-order models and reduced-order observers with eigenvalue/eigenvector assignment procedures is investigated. A review of spectral assignment synthesis procedures is presented. Then, a reduced-order model which retains essential system characteristics is formulated. A constant state feedback matrix which assigns desired closed loop eigenvalues and approximates specified closed loop eigenvectors is calculated for the reduced-order model. It is shown that the eigenvalue and eigenvector assignments made in the reduced order system are retained when the feedback matrix is implemented about the full order system. In addition, those modes and associated eigenvectors which are not included in the reduced-order …

Derivations For Discrete-Time Cumulant Control, Henk Albert Roelant

Electrical & Computer Engineering Theses & Dissertations

Expressions for discrete-time cumulant control systems are derived. These expressions are useful for both control system performance analysis and controller selection. Derivation of the performance cumulant expressions parallels the development for the continuous-time case. Two matrix difference equations based on the first two-cumulants are derived. A heuristic procedure for controller selection using the two matrix difference equations paralleling the procedure for the continuous-time case is developed.

The Development Of A Microprocessor Controlled Linearly Actuated Valve Assembly, Raymond H. Wall

Mechanical & Aerospace Engineering Theses & Dissertations

The development of a proportional fluid control valve/assembly is presented. This electro-mechanical system is needed for space applications to replace the current proportional flow controllers that use bulky hydraulic or pneumatic actuation systems. The flow is controlled by a microprocessor system that monitors the control parameters of upstream pressure and requested volumetric flow rate. The microprocessor achieves the ·proper valve stem displacement by means of a digital linear actuator. A linear displacement sensor is used to measure the valve stem position. 'Ibis displacement is monitored by the microprocessor system as a feedback signal to close the control loop. With an …

Error Codes In Digital Data Communication Systems, Robert Hadley Cravens

Dissertations and Theses

Today’s digital communication systems perform data transfers at the rate of millions of bits per minute, with data errors in the order of 1/6th error per day. This magnitude of errorless communication is now possible because of sophisticated error correcting codes. Many types of error codes are employed today in three distinct areas of digital data communication: human to computer; data source to computer; computer to computer; and intra-computer; we are concerned here with intra-computer communication.

This research is primarily a mathematical study of error codes in general to explore the possibilities of each major type for the purpose of …

The Random Sequence Closing Control System, Henri Bernard Joyaux

Dissertations and Theses

This thesis describes a digital control system used by the Network Analog Group of the Bonneville Power Administration. This system, the Random Sequence Closing Control System, provides automatic control for a special purpose analog computer used in the study of switching surge over voltages on power transmission lines. This system, which uses pseudorandom data, has made it feasible to analyze switching surge phenomena on a statistical basis.

Simulation And Analysis Of A Second-Order System With An Added Finite Pole And/Or Zero, William Robert Bodwell

Electrical & Computer Engineering Theses & Dissertations

An original system whose transfer functions consist of two infinite zeros and two finite poles is modified by the addition of a finite pole and/or finite zero. Statespace techniques are used to obtain equations for simulating the transfer functions on both analog and digital computers. Sample cases were selected and simulated to demonstrate the various types of responses. Analysis of the computer results and mathematical analysis of the transfer functions provide nomographs for estimating the response of the systems to a step-input and methods for obtaining equivalent pole/zero configurations.