autonomous collision avoidance for unmanned aerial systems

222 Pages·2014·19.97 MB·English

by  Marco Melega

Cranfield University
Marco Melega
AUTONOMOUS COLLISION
AVOIDANCE FOR UNMANNED
AERIAL SYSTEMS
School of Engineering
Department of Engineering Physics
Autonomous and Intelligent Systems Group
Ph.D.Thesis
Supervisors:
Dr. Al Savvaris
Dr. Antonios Tsourdos
2014

Cranfield University
School of Engineering
Department of Engineering Physics
Autonomous and Intelligent Systems Group
Ph.D.Thesis
Marco Melega
AUTONOMOUS COLLISION
AVOIDANCE FOR UNMANNED
AERIAL SYSTEMS
Supervisors:
Dr. Al Savvaris
Dr. Antonios Tsourdos
2014
This thesis is submitted in partial fulfilment of the requirements for the degree of Ph.D..
c Cranfield University 2014. All Rights Reserved. No part of this publication may be
(cid:13)
reproduced without the written permission of the copyright holder.

Abstract
Unmanned Aerial System (UAS) applications are growing day by day and this will
lead Unmanned Aerial Vehicle (UAV) in the close future to share the same airspace
of manned aircraft.This implies the need for UAS to define precise safety standards
compatible with operations standards for manned aviation. Among these standards
the need for a Sense And Avoid (S&A) system to support and, when necessary, sub-
stitute the pilot in the detection and avoidance of hazardous situations (e.g. midair
collision, controlled flight into terrain, flight path obstacles, and clouds).
This thesis presents the work come out in the development of a S&A system taking
into account collision risks scenarios with multiple moving and fixed threats. The
conflict prediction is based on a straight projection of the threats state in the future.
The approximations introduced by this approach have the advantage of high update
frequency (1Hz) of the estimated conflict geometry. This solution allows the algorithm
to capture the trajectory changes of the threat or ownship. The resolution manoeuvre
evaluation is based on a optimisation approach considering step command applied to
the heading and altitude autopilots. The optimisation problem takes into account
the UAV performances and aims to keep a predefined minimum separation distance
between UAV and threats during the resolution manouvre. The Human-Machine
Interface (HMI) ofthisalgorithmisthenembeddedinapartialGround Control Station
(GCS) mock-up with some original concepts for the indication of the flight condition
parameters and the indication of the resolution manoeuvre constraints.
Simulations of the S&A algorithm in different critical scenarios are moreover in-
cludedtoshowthealgorithmcapabilities. Finally, methodologyandresultsofthetests
and interviews with pilots regarding the proposed GCS partial layout are covered.
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Acknowledgements
The author wishes to express sincere appreciation to Dr. Al Savvaris for the support
given in the accomplishment of the work here described. He wants moreover to warmly
thanks my family for believing in me and getting behind me in this important part of
my life.
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List of Contents
Abstract i
Acknowledgements iii
1 Introduction 1
1.1 UAVs and UASs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Unmanned Aerial System Today . . . . . . . . . . . . . . . . . . . . . 2
1.3 New Rules to Allow UAVs to Fly . . . . . . . . . . . . . . . . . . . . 4
1.4 UAS Human Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Situation Awareness and Equivalent Level of Safety for UAS . . . . . 6
1.6 UAS Airworthiness . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.7 Contributions to Knowledge of this Project . . . . . . . . . . . . . . . 8
1.8 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.9 Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.10 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Control of UAVs 13
2.1 Short History of UASs evolution . . . . . . . . . . . . . . . . . . . . . 13
2.1.1 Early Developments . . . . . . . . . . . . . . . . . . . . . . . 13
2.1.2 World War I . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.1.3 Interwar Period . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.4 World War II . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.1.5 Post-War . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.1.6 Vietnam War . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.1.7 Modern Era . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.2 UAV Level of Autonomy . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3 Supervisory Controller . . . . . . . . . . . . . . . . . . . . . . . . . . 26
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2.4 GCS Human-Machine Interface Design . . . . . . . . . . . . . . . . . 28
2.5 Direct Control Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.6 Multimodal/Multisensory Interface . . . . . . . . . . . . . . . . . . . 30
2.7 Supervisory Control Interfaces . . . . . . . . . . . . . . . . . . . . . . 31
2.8 Novel Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.8.1 Soft Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.8.2 PDA Based Interface . . . . . . . . . . . . . . . . . . . . . . . 35
2.8.3 Speech-Based Input . . . . . . . . . . . . . . . . . . . . . . . . 35
2.9 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3 Sense and Avoid Literature Review 39
3.1 General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.2 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3 Operating Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.4 Rules of Air and S&A . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.5 Operator Involvement in S&A Systems . . . . . . . . . . . . . . . . . 45
3.5.1 Effect of Link Latency and Criticality . . . . . . . . . . . . . . 46
3.6 Automatic Collision Detection in Manned Aviation . . . . . . . . . . 48
3.7 Alerting System Design . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.8 Design Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.8.1 Conflict Detection . . . . . . . . . . . . . . . . . . . . . . . . 53
3.8.2 Avoidance manoeuvre Planning . . . . . . . . . . . . . . . . . 56
3.8.3 General notes . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.9 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4 Previous Works on GCS and S&A Integration 61
4.1 GCS and situation awareness . . . . . . . . . . . . . . . . . . . . . . 61
4.2 UAS and Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.3 GCS Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4.4 Primary Flight Display . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.5 S&A Display Design Guidelines . . . . . . . . . . . . . . . . . . . . . 69
4.6 CDTI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.7 2D Planner Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.8 Synthetic Vision System . . . . . . . . . . . . . . . . . . . . . . . . . 74