Agressive flight control techniques for a fixed wing unmanned aerial vehicle
Date
2009-03
Authors
Gaum, Dunross Rudi
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
This thesis investigates aggressive all-attitude flight control systems. These are flight controllers
capable of controlling an aircraft at any attitude and will enable the autonomous
execution of manoeuvres such as high bank angle turns, steep climbs and aerobatic flight
manoeuvres. This class of autopilot could be applied to carry out evasive combat manoeuvres
or to create more efficient and realistic target drones.
A model for the aircraft’s dynamics is developed in such a way that its high bandwidth
specific force and moment model is split from its lower bandwidth kinematic
model. This split is done at the aircraft’s specific acceleration and roll rate, which enables
the design of simple, decoupled, linear attitude independent inner loop controllers to
regulate these states. Two outer loop kinematic controllers are then designed to interface
with these inner loop controllers to guide the aircraft through predefined reference trajectories.
The first method involves the design of a linear quadratic regulator (LQR) based
on the successively linearised kinematics, to optimally control the system. The second
method involves specific acceleration matching (SAM) and results in a linear guidance
controller that makes use of position based trajectories. These position based trajectories
allow the aircraft’s velocity magnitude to be regulated independently of the trajectory
tracking. To this end, two velocity regulation algorithms were developed. These
involved methods of optimal control, implemented using dynamic programming, and
energy analysis to regulate the aircraft’s velocity in a predictive manner and thereby
providing significantly improved velocity regulation during aggressive aerobatic type
manoeuvres.
Hardware in the loop simulations and practical flight test data verify the theoretical
results of all controllers presented
Description
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.
Keywords
Drone aircraft, Flight control, Dissertations -- Electronic engineering, Theses -- Electronic engineering