Thesis-2016-Coombes.pdf (47.2 MB)
Download fileLanding site reachability and decision making for UAS forced landings
thesis
posted on 2016-05-05, 15:25 authored by Matthew CoombesAfter a huge amount of success within the military, the benefits of the use of unmanned
aerial systems over manned aircraft is obvious. They are becoming cheaper and their functions
advancing to such a point that there is now a large drive for their use by civilian operators.
However there are a number of significant challenges that are slowing their inevitable
integration into the national airspace systems of countries. A large array of emergency
situations will need to be dealt with autonomously by contingency management systems
to prevent potentially deadly incidences. One such emergency situation that will need autonomous
intervention, is the total loss of thrust from engine failure. The complex multi
faceted task of landing the stricken aircraft at a potentially unprepared site is called a forced
landing.
This thesis presents methods to address a number of critical parts of a forced landing
system for use by an unmanned aerial system. In order for an emergency landing site to be
considered, it needs to be within glide range. In order to find a landing site s reachability
from the point of engine failure the aircraft s glide performance and a glide path must be
known. A method by which to calculate the glide performance, both from aircraft parameters
or experiments is shown. These are based on a number of steady state assumptions to
make them generic and quick to compute. Despite the assumptions, these are shown to have
reasonable accuracy.
A minimum height loss path to the landing site is defined, which takes account of a
steady uniform wind. While this path is not the path to be flown it enables a measure of how
reachable a landing site is, as any extra height the aircraft has once it gets to the site makes
a site more reachable. It is shown that this method is fast enough to be run online and is
generic enough for use on a range of aircraft.
Based on identified factors that make a landing site more suitable, a multi criteria decision
making Bayesian network is developed to decide upon which site a unmanned aircraft
should land in. It can handle uncertainty and non-complete information while guaranteeing
a fast reasonable decision, which is critical in this time sensitive situation.
A high fidelity simulation environment and flight test platform are developed in order to
test the performance of the developed algorithms. The test environments developed enable rapid prototyping of algorithms not just within the scope of this thesis, but on a range of
vehicle types. In simulation the minimum height loss paths show good accuracy, for two
completely different types of aircraft. The decision making algorithms show that they are
capable of being ran online in a flight test. They make a reasonable decision and are capable
of quickly reacting to changing conditions, enabling redirection to a more suitable landing
site.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Aeronautical and Automotive Engineering
Publisher
© Matthew CoombesPublisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2016Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.Language
- en