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Zhao, YueAutomatic Prevention and Recovery of Aircraft Loss-of-Control by a Hybrid Control Approach
Doctor of Philosophy (PhD), Ohio University, 2016, Electrical Engineering & Computer Science (Engineering and Technology)
In this dissertation, an integrated automatic flight controller for fixed-wing aircraft Loss-of-Control (LOC) Prevention and Recovery (iLOCPR) is designed. The iLOCPR system comprises: (i) a baseline flight controller for six degrees-of-freedom (6DOF) trajectory tracking for nominal flight designed by trajectory linearization, (ii) a bandwidth adaption augmentation to the baseline controller for LOC prevention using the timevarying PD-eigenvalues to trade tracking performance for increased stability margin and robustness in the presence of LOC-prone flight conditions, (iii) a controller reconfiguration for LOC arrest by switching from the trajectory tracking task to the aerodynamic angle tracking in order to recover and maintain healthy flight conditions at the cost of temporarily abandoning the mission trajectory, (iv) a guidance trajectory designer for mission restoration after the successful arrest of a LOC upset, and (v) a supervisory discrete-eventdriven Automatic Flight Management System (AFMS) to autonomously coordinate the control modes (i) - (iv). Theoretical analysis and simulation results are shown for the effectiveness of the proposed methods.

Committee:

Jim Zhu (Advisor); Douglas Lawrence (Committee Member); Frank Van Grass (Committee Member); Robert Williams (Committee Member); Aili Guo (Committee Member); Sergiu Aizicovici (Committee Member)

Subjects:

Aerospace Engineering; Engineering

Keywords:

Aircraft Loss-of-control; hybrid; arrest; prevention; recovery; flight control system; arrest; guidance; trajectory linearization control; switching mode; reconfiguration; bandwidth adaptation; multiple-time-scale nested loop

Bhatia, AbhishekMultivariable Feedback Control of Unstable Aircraft Dynamics
MS, University of Cincinnati, 2016, Engineering and Applied Science: Aerospace Engineering
The purpose of a flight control system is to provide stability and control for the aircraft with the help of control surfaces. FCS helps improve aircraft performance characteristics during flight. Stability is secured by the mechanism of feedback. Feedback plays an important part in providing a baseline control approach for stabilizing a non-linear unstable aircraft. It helps suppress effects of disturbances. Numerical Linearization is used to design a stabilizing controller for a non-linear model of the F-16 Fighting Falcon jet initialized with nominal flight condition. First a single-loop at a time feedback is designed using Matlab for longitudinal stabilization. Then the lateral modes of the aircraft are fed back and used in a single-loop at a time fashion to stabilize the lateral dynamics. Then, a multivariable feedback approach is used to stabilize the lateral dynamics for a constant turn rate condition using a cost function optimization approach to find suitable gains for the feedback loops. All of these controllers are tested by using a non-linear Simulink simulation of the scale-model F-16 dynamics

Committee:

Bruce Walker, Sc.D. (Committee Chair); Kelly Cohen, Ph.D. (Committee Member); David Thompson, Ph.D. (Committee Member)

Subjects:

Aerospace Materials

Keywords:

Flight Control System;F-16;Feedback;Linearization;Stabilization;Optimization