Metin Kus

ORCID Identifier(s)

0000-0003-1928-1618

Graduation Semester and Year

2019

Language

English

Document Type

Thesis

Degree Name

Master of Science in Aerospace Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Kamesh Subbarao

Abstract

This study focuses on the design, implementation, and evaluation of an autonomous carrier landing system featuring an airborne deck motion estimation module. The three-dimensional dynamics of a fixed-wing UAV with the actuator and engine dynamics are considered. A carrier motion model that accounts for the perturbations caused by various sea states is built. An airborne measurement system, which is composed of a calibrated camera and light-emitting beacons, is utilized to detect several coplanar target points on the moving carrier deck. The known correspondence between the locations of the target points and their coordinates on the focal plane of the camera is exploited in the estimation of the desired touchdown point location and runway attitude. The estimation problem is posed as a nonlinear least-squares problem where the error between the actual value and a current estimate of the measurement is minimized in successive iterations. A second-order, low-pass filter is employed to estimate the velocity of the desired touchdown point. A reference trajectory is generated based on the estimated motion of the desired touchdown point and a glide path. The dynamic inversion technique is used in the derivation of guidance laws to produce a flight-path command to achieve the reference trajectory. A Linear-Quadratic-Integral (LQI) optimal controller is designed to track the flight-path command and stabilize the aircraft around an equilibrium point. The system is evaluated through simulation. Monte Carlo simulations for various sea states with randomized initial conditions demonstrate robustness, ensuring a wide range of initial conditions and possible scenarios are covered. The system performance is shown to be satisfactory based on several figures of merit, including boarding rate, landing dispersion, angular alignment, and impact velocity even in the worst sea condition considered in this study. Also, the efficiency of the estimation algorithm indicates the feasibility of real-time implementations. In the navigation system, a Position Sensing Diode (PSD) is located on the focal plane of the camera to detect the modulated light emitted by the beacons. The system performance is evaluated for a range of sampling rates of the PSD. Monte Carlo simulations indicate satisfactory performance for a wide range of sampling rates, from 5Hz to 100Hz.

Keywords

Carrier landing, Guidance, Vision navigation, Optimal control, Airborne estimation, Nonlinear least squares, Linear quadratic regulator, Trajectory planning

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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