Fit-for-purpose Unmanned
Aerial Vehicle Flight
Dynamics Model for Sense
and Avoid Maneuvers
PhD Proposal Presentation – June 8
th
2017
by
Oihane Cereceda
2
Content
Introduction
–
Problem Statement
–
Technical difficulties
–
Objectives
–
Scope
–
End goals
–
Contributions
Literature review and theoretical background
Experimental results
–
Fixed-wing UAV FDM first approach
–
V&V Methodology for UAV FDM
–
Design and V&V 6-DOF EPP-FPV JSBSim FDM
–
SAA high performance maneuver
Expected results
Conclusions
Introduction
3
Problem Statement
PhD Proposal Presentation – June 8
th2017
UAV
current
status
More
restrictive
regulations
Integration of
UAVs in the
current
airspace
Limited flight
tests
Flight
Dynamics
Model
SAA
techniques
integrated in
the UAVs
V&V
Methodology
Has led to..
Has led to..
Meaning that..
Consequence
+
How to develop SAA
with limited flight tests?
• Small signals
• Medium signals
• Large signals
SAA strategies
SIMULATORS
How to design a
high fidelity model?
Introduction
4
Technical difficulties
PhD Proposal Presentation – June 8
th2017
• Open source software
• Minimum flight tests
Scope
• Design and definition of the FDM (computer modeling)
• Minimum flight tests only when designing the model
Objectives
• Design a UAV FDM whose performance is the same as a real model using a
V&V methodology
• Implement the model in a computer environment
• Simulate a defined SAA strategy
5
PhD Proposal Presentation – June 8
th2017
End Goals
Introduction
1. Develop a 6-DOF UAV FDM in
JSBSim for testing SAA
2. Specify a V&V method for UAV FDM
3. Validate the FDM designed in 1)
4. Requirements for an optimal
avoidance maneuver
5. Calculate the maneuver properties
from the performance
6. Determine those properties form a
mathematical point of view
V&V methodology for UAV FDM
JSBSim FDM for UAVs
Avoidance maneuver
1.
Add two UAV FDM to the online library: GiantBig Stik and EPP FPV
2.
Technical report: Simplified version of JSBSim for UAVs
3.
Open the discussion to UAV FDM V&V
4.
Demonstrate the V&V methodology reliability
5.
Validate JSBSim as a computer model software for fixed-wing UAVs
6
End Goals
1. Develop a 6-DOF UAV FDM in
JSBSim for testing SAA
2. Specify a V&V method for UAV FDM
3. Validate the FDM designed in 1)
4. Requirements for an optimal
avoidance maneuver
5. Calculate the maneuver properties
from the performance
6. Determine those properties form a
mathematical point of view
V&V methodology for UAV FDM
JSBSim FDM for UAVs
Avoidance maneuver
Introduction
6.
Define the best avoidance maneuver according to the current regulations
7.
Converge the simulation and mathematical results into a 2D manauver
8.
Synchronization of manned and unmanned aircrafts in a computer environment
PhD Proposal Presentation – June 8
th2017
Visualization
software
Related work
7
PhD Proposal Presentation – June 8
th2017
FDMs and simulation software
Software
Visual Environment
Highlights
Status
Comments
ODE
[10]+
V-REP or ROS
[12]Included in the software
Models collisions between dynamic
bodies
Active
Rejected
ROS
[12]+
Gazebo
[11]Gazebo
Does
not
require
significant
computation
Publish/subscribe system
Active
Dismissed in
2015
MATLAB/Simu
link
AeroSim
[13]Simulink +
FlightGear
[16]
Graphical environment and setup
Well-known software
Out-of-date
Not viable
JSBSim
In current
develop-ment
Not enough
resources
JSBSim + scripts
FlightGear
Open to design with an on-line library
Flexible programming
No incompatibilities with neither OS
nor old versions
Up-to-date
Best solution
FDM
Ref: [7]-[17]
Simulation
software
8
PhD Proposal Presentation – June 8
th2017
Related work
V&V techniques
Categories for general aircraft validation [22]:
• Generalized software V&V
• Observation/Inspection of aircrafts model
actions and performance
• Regulatory agency simulation qualification
• Experimental flight testing
• Maintenance flight testing
• Pilot manual standardization
• Pilot’s operating handbook
V&V expressed in High Level [19]
V&V
methodology
for UAV FDM
Existing
V&V FDM
Methods
•
Time
delays
in
communication
•
Human in-the-loop
•
Cockpit view vs. R/C view
(excluding first-person view)
•
Maneuvers nature
9
PhD Proposal Presentation – June 8
th2017
Related work
Sense and Avoid (SAA) strategies
Sense and Avoid
“The capability to see, sense or detect conflicting
traffic or other hazards and take the appropriate
action to comply with the applicable rules of
flight” [23]
Other applications of SAA methods
•
Landing approaches
•
Target detection and recognition
•
Search and Rescue
SAA
maneuver
Time to
collision
UAV
capabilities
Environment
Separation thresholds [25]:
WCV: Well-clear violation
CAT: Collision avoidance threshold
NMAC: Near Mid-Air collision. R:500ft, H:200ft
10
PhD Proposal Presentation – June 8
th2017
Theoretical background
Flight Dynamics Model and Flight control
Equations
of motion
Propulsion
Aerodynamics
Atmosphere
and Earth
Linear velocities
Angular velocities
Attitude
Location
11
Aerodynamics
Lift coefficient as an example:
The Lift coefficient is calculated from all the contributions to the force.
The aerodynamic force is then calculated using the dynamic pressure.
The same procedure is done for the Side and Drag forces and Roll, Pitch
and Yaw moments.
12
Equations
of motion
From the second
Newton’s law including the rotating
reference frame:
The motion rates according to the rotating moment of inertia definition are:
13
Fixed-wing UAV FDM first
approach
PhD Proposal Presentation – June 8
th2017
AeroSim in MATLAB/Simulink
Waypoints
Tracking path
Roll, Pitch and Throttle
Suggested V&V method
14
PhD Proposal Presentation – June 8
th2017
What is the problem to overcome?
What is the scope of the final simulation?
What is the computer model for?
What are the criteria and the accuracy to fulfill?
PHASE 1
*Submitted to
IEEE
Transactions on
Aerospace and
Electronic Systems
Suggested V&V method
15
PhD Proposal Presentation – June 8
th2017
Method A: Flying Recommendations -> follow manufacturers suggestions for taking off, landing and
level flight.
Method B: Model observation -> R/C pilot testing
PHASE 2
*Submitted to
IEEE
Transactions on
Aerospace and
Electronic Systems
16
Elevator test
Aileron test
Rudder test
Suggested V&V method
PHASE 3A – Computer test
16
PhD Proposal Presentation – June 8
th2017
*Submitted to
IEEE
Transactions on
Aerospace and
Electronic Systems
Suggested V&V method
PHASE 3B
17
PhD Proposal Presentation – June 8
th2017
Case study
18
PhD Proposal Presentation – June 8
th2017
EPP-FPV FDM using JSBSim
What is the problem to overcome?
What is the scope of the final simulation?
What is the computer model for?
What are the criteria and the accuracy to fulfill?
PHASE 1
-
Sense and Avoid trajectories with extreme maneuvers
-
AeroSim in MATLAB/Simulink as the reference FDM in Phase 3A
-
Full range of signals
-
Large signals in computer test –
Phase 3A
-
Small and medium signals in
Phase 3B
-25
o-20
o-15
o-10
o10
o15
o20
o25
oElevator
Aileron
Case study
19
EPP-FPV FDM using JSBSim
Method A: Flying Recommendations -> follow manufacturers suggestions for taking off, landing and
level flight.
Method B: Model observation -> R/C pilot testing
PHASE 2
No
relevant
information
in
the
flying
recommendations from the manufacturer.
From R/C pilots in online forums:
-
Rudder should be used to support turns in
addition to the ailerons.
-
Very light and hard to fly it manually.
By inspection:
-
Poor stability in the first seconds.
-
Sensitive to the change of commands
20
PhD Proposal Presentation – June 8
th2017
Case study
EPP-FPV FDM using JSBSim
PHASE 3A – Computer test
Static test
Elevator test
Aileron test
Rudder test
21
Phase 3A: Static test
22
Phase 3A: Open-loop test ELEVATOR
The responses are considered the same with:
-
Max error in pitch: 1%
-
Error in airspeed: 2.5%
When the angle of attack is increased in the aircraft due to a downward lift
created by a negative elevator deflection, the nose pitches up and the airspeed
decreases; making the opposite effect when the elevator deflection is positive.
23
Phase 3A: Open-loop test AILERONS
•
Significant effect of roll on sideslip
motion
•
The system is coherent from a physical point of view
•
JSBSim has a faster performance
24
Phase 3A: Open-loop test RUDDER
•
JSBSim has better stability
25
Phase 3B: Flight tests
•
Offset due to different initial states
•
External forces in the flight tests that are not modelled in a computer test
•
Communication delay between controller and actuators
26
Case study
EPP-FPV FDM using JSBSim
END PHASE. Discussion
•
The rudder should be used as support when turning as demonstrated in
Phase 3A. No flight tests were done with the use of rudder.
•
SAA maneuvers require extreme maneuvers with large signals even in
Phase 3B.
•
Certain differences must be allowed due to the no implementation of
those in the computer environment.
27
PhD Proposal Presentation – June 8
th2017
SAA high performance
maneuver
1.
Obtain the maximum achievable climb and
descend rate for vertical only SAA
maneuver.
2.
Obtain the maximum achievable turn rate
with no changes in altitude for horizontal
only maneuver
Objectives
Manned
aircraft
detects the
UAV
Manned
aircraft does
not detect
Manned
aircraft
anticipates
the UAV
Unlikely scenario in
civil applications
1
stapproach
Real case
In which scenarios?
GiantBig Stick:
-Provides high performance for extreme maneuvers
-Large range of signals
-Representative UAV for testing SAA maneuvers in NMAC
scenarios
28
Expected results
Semester
Tasks
Spring 2014
ENGI9940 – Advanced Robotics: Completed
Fall 2014
ENGI9516 – Design of Experiments: Completed
Spring 2016
Comprehensive examination: Passed
Spring 2017
Paper 1 submitted to IEEE Transactions on Aerospace and Electronic
Systems
Spring 2017
Research proposal presentation
Fall 2017
Paper 2
End of 2017 Finalize the research
Winter 2018 Write thesis – Paper 3
Spring 2018 PhD Defense
PhD Proposal Presentation – June 8
th2017
PAPER 1: Verification and Validation Methodology for a Fixed-wing Unmanned Aerial Vehicle using
JSBSim as a case study (O. Cereceda, K. Murrant, L. Rolland and S. O’Young)
Submitted to IEEE Transactions on Aerospace and Electronic Systems
PAPER 2: Definition of the SAA maneuver. Adjust the current computer model fit for purpose for the
task. Determine the inputs to the system according to the scenarios described in previous slide.
29
Summary
A
B
C
Mathematical
model
Computer
model
Flight/Real
model
PART I. Modelling and V&V
•
A
≈ B allowing certain differences on top of
the mathematical model
•
B ≈ C allowing certain tolerance between the
computer
and
the
flight
model
due
to
uncontrollable elements like delays and external
forces
•
A≠C
Objective: Design a FDM that expresses the
dynamics of the real system for a desired
and well-defined task
Tool: V&V Methodology for UAV FDM
PART II. SAA
maneuvers
PhD Proposal Presentation – June 8
th2017
30
Summary
PART II. Sense and Avoid
PhD Proposal Presentation – June 8
th2017
•
Context:
Representative UAV: GiantBig Stik
Representative manned aircraft: Cessna 172
•
Scenarios. Synchronized environments:
The manned aircraft does not detect the presence of the UAV
The manned aircraft is assumed to be in manual mode
The manned aircraft knows and anticipates the UAV future states
Objective: Definition of vertical and horizontal SAA maneuvers:
Maximum achievable climb and descend rate
Maximum achievable turn rate holding altitude
Conclusions
31
PhD Proposal Presentation – June 8
th2017
• SAA maneuvers need full 6-DOF computer models for large
signals.
• Certain tolerances must be allowed between the mathematical,
computer and real model.
• A fit-for-purpose computer model for a specific task mitigates those
differences.
• A V&V methodology has been defined as the tool to design a UAV
6-DOF FDM in JSBSim. This work has been submitted to
IEEE
Transactions on Aerospace and Electronic Systems.
• Knowing the limitations of the manned aircraft and the current
regulations it can be determined the UAV climb/descent and turn rate
for different scenarios.
32
References
32
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