etd-tamu-2005A-AERO-Hur

222 Pages·2005·3.85 MB·English

IDENTIFICATION OF POWERED PARAFOIL-VEHICLE DYNAMICS
FROM MODELLING AND FLIGHT TEST DATA
A Dissertation
by
GI-BONG HUR
Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
May 2005
Major Subject: Aerospace Engineering
© 2005

GI-BONG HUR

ALL RIGHTS RESERVED
IDENTIFICATION OF POWERED PARAFOIL-VEHICLE DYNAMICS
FROM MODELLING AND FLIGHT TEST DATA
A Dissertation
by
GI-BONG HUR
Submitted to Texas A&M University
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
Approved as to style and content by:
John Valasek
(Chair of Committee)
Donald Ward John Junkins
(Member) (Member)
John Painter Helen Reed
(Member) (Head of Department)
May 2005
Major Subject: Aerospace Engineering
iii
ABSTRACT
Identification of Powered Parafoil-Vehicle Dynamics from Modelling and Flight Test
Data. (May 2005)
Gi-Bong Hur, B.S.; M.S., Seoul National University, Korea
Chair of Advisory Committee: Dr. John Valasek
During the final approach and landing phase of the X-38/Crew Return Vehicle, a
steerable parafoil is used to maneuver and land at a targeted ground base under
autonomous control. To simulate and verify performance of the onboard Parafoil
Guidance, Navigation and Control system (PGNC), a commercial powered parafoil-
vehicle, called the Buckeye consisting of a parafoil and vehicle two-body system like
the X-38/CRV was modified to accommodate the avionics and scale-downed parafoil
for aerodynamic similarity and a series of flight tests were conducted.
Dynamic modelling and system identification results for the Buckeye are de-
scribed in this dissertation. The vehicle dynamics are modelled as all 8 degrees-of-
freedom system comprising 6 states for the parafoil and 2 states for the relative pitch
and yaw motion of the vehicle with respect to the parafoil. Modal analysis for the
linearized model from the nonlinear model shows the number and order of dynamic
modes as well as the system is controllable and observable. For system identifica-
tion, the overparameterized Observer/Kalman Filter Identification (OKID) method
is applied to identify a linear model of the Buckeye two-body system from the flight
data assuming that disturbances at a calm day are represented as periodic distur-
bances. The identification results show that the overparameterized OKID works well
for powered parafoil-vehicle two-body system identification under calm day condi-
tions using flight data. For the data with possible discrete gusts the OKID shows
limitation to identify a linearized model properly. Several sensor packages including
airdata and Inertial Measurement Unit are designed and installed for the parameters
for identification. The sensor packages successfully supply data of the parameters for
identificationandsuggest afeasible, lowcostmethodfortheparafoil-vehicletwo-body
dynamic parameters.
iv
With love,
this dissertation is dedicated to
my mother who has sacrificed all her life for her children,
my wife Eunju,
my adorable kids Yoonjung and Jaewon, and
my parents-in-law who presented me more than a lovely wife.
v
ACKNOWLEDGMENTS
The author wishes to thank all of the people whose assistance, support and love have
contributed by whatever amount to this research effort. The author would like to
thank Dr. John Valasek for his academic guidance and financial support. Without
his advice and encouragement, this work could not have been completed. The author
also wishes thank to Dr. John Junkins, Dr. John Painter and Dr. Don Ward for their
precious advice and support in serving as committee members. All of them impressed
the author with their virtuous life as well as academic achievements. Dr. Ward and
Mr. David Lund deserve special recognition for their extensive help in flight testing
as well as financial support for the test. Their support with valuable flight data
continued after the project concluded and will not be forgotten. The author would
like to give special thanks to NASA’s Alan Strahan and Ron Sostaric for supporting
theflighttestproject. Theauthoralsoacknowledges DavidOgdenandCarlBargainer
from SwRI for supporting the hardware implementation and testing. Valencia Lund,
John Wilkey, Edward Caicedo, Bryan Wood and the others in the Flight Mechanics
Lab. must be included in the author’s appreciation for their extensive support during
the tests in the field.
The author’s mother, brother and sisters merit special recognition for their love,
trustandsupportthroughout. Inaddition,theauthorwouldliketothankhisparents-
in-law for their love and support throughout the study.
Finally the author thanks his wife, Eunju, for her love, patience, prayers and
encouragement through the duration of his stay in America and his kids, Yoonjung
and Jaewon, who have been waiting for their daddy till late every night. The author
would like to tell his kids, ”I will spend much more time with you from now on.”
vi
TABLE OF CONTENTS
CHAPTER Page
. . . . . . . . . . . . . .
I INTRODUCTION AND BACKGROUND 1
1.1 Research Objectives . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Flight Test Vehicle Description . . . . . . . . . . . . . . . . . 6
1.3 Organization of the Dissertation . . . . . . . . . . . . . . . . . 9
. . . . . . . . . . . . . . . . . . . . . . .
II ANALYTICAL MODEL 10
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Coordinate Systems . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Nonlinear Equations of Motion . . . . . . . . . . . . . . . . . 14
2.3.1 Introduction of Kane’s Equation . . . . . . . . . . . . . 14
2.3.2 8-DOF Equations of Motion . . . . . . . . . . . . . . . 18
2.3.2.1 Kinematics . . . . . . . . . . . . . . . . . . . . . 19
2.3.2.2 Generalized Forces . . . . . . . . . . . . . . . . . 23
2.4 Linearized Equation of Motion . . . . . . . . . . . . . . . . . . 35
2.4.1 Linearized Model . . . . . . . . . . . . . . . . . . . . . 37
2.5 Modal Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.5.1 Longitudinal Motion . . . . . . . . . . . . . . . . . . . . 49
2.5.2 Lateral/Directional Motion . . . . . . . . . . . . . . . . 54
2.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
. . . . . . . . . . . . . .
III SYSTEM IDENTIFICATION METHOD 58
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.2 Observer Kalman-Filter Identification Formulation . . . . . . 58
3.3 OKID under Disturbance . . . . . . . . . . . . . . . . . . . . . 68
3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
. . . . . . . . . . . . . . . . . . . . . . .
IV EXPERIMENT DESIGN 75
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.2 Data Acquisition System and Installation . . . . . . . . . . . . 76
4.2.1 Air Data sensor . . . . . . . . . . . . . . . . . . . . . . 77
4.2.2 Inertial Measurement Unit . . . . . . . . . . . . . . . . 78
4.2.3 Sensors for Parafoil Motion . . . . . . . . . . . . . . . . 82
4.2.3.1 Accelerometers . . . . . . . . . . . . . . . . . . . 82
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CHAPTER Page
4.2.3.2 Wireless Data Acquisition System . . . . . . . . . 84
4.2.4 Multi-rate Data Acquisition . . . . . . . . . . . . . . . . 86
4.3 OKID Application for Nonlinear Simulation Data . . . . . . . 86
4.3.1 Identified Linear Model and Time Histories . . . . . . . 87
4.3.2 Input Survey through Simulation Analysis . . . . . . . . 87
4.4 Flight Test Design . . . . . . . . . . . . . . . . . . . . . . . . 92
4.4.1 Test Procedures . . . . . . . . . . . . . . . . . . . . . . 93
4.4.2 Test Inputs . . . . . . . . . . . . . . . . . . . . . . . . . 94
4.4.3 Flight Tests . . . . . . . . . . . . . . . . . . . . . . . . 94
4.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
. .
V IDENTIFICATION RESULTS FROM FLIGHT TEST DATA 100
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
5.2 Data Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . 100
5.2.1 Air Data . . . . . . . . . . . . . . . . . . . . . . . . . . 100
5.2.2 IMU Data . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.2.3 Parafoil Accelerometers . . . . . . . . . . . . . . . . . . 111
5.2.4 Synchronization of Multi-rate Sensor Outputs . . . . . . 114
5.3 OKID Application to Flight Test Data . . . . . . . . . . . . . 115
5.3.1 Identified Linear System Model . . . . . . . . . . . . . . 117
5.3.1.1 Longitudinal Model . . . . . . . . . . . . . . . . . 123
5.3.1.2 Lateral/Directional Model . . . . . . . . . . . . . 126
5.3.2 Time History Comparison . . . . . . . . . . . . . . . . . 128
5.3.2.1 Longitudinal Motion . . . . . . . . . . . . . . . . 128
5.3.2.2 Lateral/Directional Motion . . . . . . . . . . . . . 133
5.4 Modal Analysis of Identified Model . . . . . . . . . . . . . . . 135
5.4.1 Longitudinal . . . . . . . . . . . . . . . . . . . . . . . . 135
5.4.2 Lateral/Directional . . . . . . . . . . . . . . . . . . . . 140
5.5 Comparison of Trajectories between Analytical and Iden-
tified Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
5.6 Error Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
. . . . . . . . . . . . . . . . .
VI SUMMARY AND CONCLUSIONS 152
. . . . . . . . . . . . . . . . . . . . . . . .
VII RECOMMENDATIONS 155
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REFERENCES 157
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDIX A 162
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Page

APPENDIX B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

APPENDIX C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

APPENDIX D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

VITA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
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LIST OF TABLES
TABLE Page
. . . . . . . . . . . .
2.1 Summary of Longitudinal Dimensional Derivatives 48
. . . . . . . . .
2.2 Summary of Lateral/Directinal Dimensional Derivatives 48
. . . . . . . . . . . .
2.3 Summary of Nominal Non-Dimensional Derivatives 49
. . . . . . . .
2.4 Geometric, Aerodynamic, and Mass Data for the Buckeye 50
. . . . . . . . . . . . . . . . . . . . .
2.5 Eigenvalues of Longitudinal Motion 54
. . . . . . . . . . . . . . . . .
2.6 Eigenvalues of Lateral/Directional Motion 57
. . . . . . . . . . . .
4.1 Technical Specification of Multifunction Aeroprobe 78
. . . . . . . . . . . . . . . . . . . . . . .
4.2 Technical Specification of IMU 78
. . . . . . . . .
4.3 Technical Specification of Accelerometers on the Parafoil 85
. . . . . . . . . . . . . . . . . . . . . .
4.4 Flight Test Log for Identification 97
. . . . . . . . . . . . . . .
5.1 Eigenvalues of Identified Longitudinal Model 126
. . . . . . . . . . . .
5.2 Eigenvalues of Identified Lateral/Directional Model 128