DEVELOPMENT OF VISION BASED NAVIGATION FOR MICRO AERIAL VEHICLES IN HARSH ...

128 Pages·2017·15.19 MB·English

DEVELOPMENT OF VISION BASED NAVIGATION FOR
MICRO AERIAL VEHICLES IN HARSH ENVIRONMENTS
HAILONG QIN
SUPERVISOR
Professor Chen Benmei
Associate Professor Zhang Yunfeng
EXAMINER
Dr Peng Kemao
Associate Professor Prahlad Vadakkepat
NATIONAL UNIVERSITY OF SINGAPORE
2017

DEVELOPMENT OF VISION BASED NAVIGATION FOR
MICRO AERIAL VEHICLES IN HARSH ENVIRONMENTS
HAILONG QIN
A THESIS SUBMITTED
FOR THE DEGREE OF MASTER OF ENGINEERING
DEPARTMENT OF ELECTRICAL AND COMPUTER
ENGINEERING
NATIONAL UNIVERSITY OF SINGAPORE
2017

Declaration
I hereby declare that this thesis is my original work and it has been
written by me in its entirety. I have duly acknowledged all the
sources of information which have been used in the thesis.
This thesis has also not been submitted for any degree in any
university previously.
HAILONG QIN
October 25, 2017
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Acknowledgements
During my four years’ research and study in NUS UAV group. I have experienced numerous
challengingprojectsandcompetitions. Luckily,withthehelpofmybestfriends,Yingcai,Jiaxin,
Menglu, Wenqi and Shan Mo, we have successfully achieved a lot of amazing achievements
together. Iwillkeepthesepreciousmomentsandmoveforward.
In addition, I’m so lucky to have Professor Ben M. Chen and Professor Yunfeng Zhang to
be my academic supervisors. They both give me a lot of precious advice and guidance on my
research project. Especially Prof.Chen, who has contributed all his efforts and time to bond
everyoneinthisgroupsothatwecanovercomesomanytoughchallenges. Hisdeterminationis
alwaysanexampletolearn.
I also want to express my great gratitude to all my colleagues in Temasek lab. Kevin, Xu
Ge,Yuchao,Pengfei,QinGeng,Xudong,Mingjie,Dandan,Dr. Gao,Yanxu,ZhangShuai. We
haveworkedtogetherandenjoyedalothappymoments. Iwanttoexpressallmygratitudeand
best wishes to my mentor, Dr. Lin Feng. Dr. Lin opens a door for me so that I can have the
opportunitytostudyandworkinUAVgroup. Moreover,hehasgivenmesomanyopportunities
andsupporttoexploretheareaswhichI’minterested.
Atlast,I’dliketothankmywife,Dr. ChenZihao,whoalwaysbymysideandsupportme.
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Contents
Acknowledgements v
Summary xi
ListofTables xiii
ListofFigures xv
ListofSymbols xix
1 Introduction 1
2 PlatformDesign 21
2.1 PlatformDesignandSpecification . . . . . . . . . . . . . . . . . . . . . . . . 21
2.1.1 Pixhawk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.1.2 OnboardComputer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.1.3 VisualSensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2 ControllerArchitecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3 VisionBasedNavigation 31
3.1 VisionBasedNavigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1.1 FeatureBasedVO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.1.2 DirectVO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
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3.1.3 MonocularOdometry . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.1.4 StereoOdometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.1.5 RGBDOdometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.2 DepthEstimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.2.1 DirectDepthSensing . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.2.2 TriangularDepthSensing . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3 Visual-InertialOdometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3.1 IMUPreintegration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.3.2 VisualOdometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.3 Downward-facingVelocityEstimation . . . . . . . . . . . . . . . . . . 45
4 DenseReconstructionandObstacleFreeTrajectoryPlanning 47
4.1 Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.2 PathPlanning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.3 DenseReconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.4 ObstacleFreeMotionPlanning . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.4.1 GlobalPathPlanner . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.4.2 LocalTrajectoryGeneration . . . . . . . . . . . . . . . . . . . . . . . 54
5 AStereoandRotatingLaserFramework 57
5.1 TerminologyandNotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.2 OverviewofMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.2.1 MotionEstimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5.3 RotatingLaserBasedMotionEstimation . . . . . . . . . . . . . . . . . . . . . 65
5.3.1 FeatureExtraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.3.2 FeatureAssociation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.3.3 MotionEstimationandMapping . . . . . . . . . . . . . . . . . . . . . 70
5.4 EKFBasedSensorFusionforStateEstimation . . . . . . . . . . . . . . . . . 73
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