Integration of RTK GPS and IMU for Accurate UAV Positioning

127 Pages·2015·15.6 MB·English

by  Bjørn Amstrup Spockeli

Integration of RTK GPS and IMU for
Accurate UAV Positioning
Integrasjon av RTK GPS og IMU for nøyaktig
UAV-posisjonering
Bjørn Amstrup Spockeli
Master of Science in Cybernetics and Robotics
Submission date: June 2015
Supervisor: Thor Inge Fossen, ITK
Norwegian University of Science and Technology
Department of Engineering Cybernetics

NTNU Faculty of Information Technology,
Norwegian University of Mathematics and Electrical Engineering
Science and Technology Department of Engineering Cybernetics

MSC THESIS DESCRIPTION SHEET

Name: Bjørn Spockeli
Department: Engineering Cybernetics
Thesis title (Norwegian): Integrasjon av RTK GPS og IMU for nøyaktig UAV-posisjonering
Thesis title (English): Integration of RTK GPS and IMU for Accurate UAV Positioning

Thesis Description: The purpose of the thesis is to improve the accuracy and reliability of RTK GPS
by implementing an observer for velocity, position and attitude of the X8 fixed-wing UAV using RTK
GPS and IMU measurements.

The following items should be considered:

1. Define the scope of the thesis and clarify what your contributions are.
2. Develop a navigational payload for the X8 fixed-wing UAV
3. Implement an observer for velocity, position and attitude based on RTK GPS and IMU data.
4. Investigate if the RTK GPS position data must be compensated for time delays and modify the
observer to compensate for time delays if necessary.
5. Test the observer in Hardware-in-the-Loop(HIL) simulations
6. Experimental testing of the observer using the payload mounted in the X8 fixed-wing UAV
7. Conclude your results.

Start date: 2015-01-05
Due date: 2015-06-18

Thesis performed at: Department of Engineering Cybernetics, NTNU
Supervisor: Professor Thor I. Fossen, Dept. of Eng. Cybernetics, NTNU
Co-Supervisor: Dr Nadia Sokolova, Dept. of Eng. Cybernetics, NTNU
Jakob Mahler Hansen, Dept. of Eng. Cybernetics, NTNU
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Abstract
Real-Time Kinematic GPS (RTK GPS) can provide centimeter accuracy and may
be used for high accuracy positioning of Unmanned Aerial Vehicles (UAVs). In
ordertocomputeitspositionaGlobalNavigationSatelliteSystem(GNSS)receiver
processes measurements of signals from GNSS satellites. The processing results in
a delay before the position measurement is available to the UAV. If the UAV is
highlydynamicthedelayedmeasurementwilldescribeapastposition, resultingin
reduced accuracy.
This thesis presents the hardware and software architecture of an integrated Real-
TimeKinematicGPS/InertialNavigationSystem(RTKGPS/INS)forUAVappli-
cations that compensates for the time-delay. The RTK GPS system is constructed
using single-frequency GPS receivers and the open-source Real-Time Kinematic
Library (RTKLIB). The RTK GPS/INS navigation system is implemented in the
DUNE(DUNE:Uni(cid:28)edNavigationEnvironment)-frameworkrunningontheembed-
dedpayloadcomputeroftheUAV.TheintegrationofRTKGPSandineartialmea-
surements is performed by a nonlinear observer estimating the delayed states and
recovering the current states using inertial measurements. Hardware-in-the-Loop
simulations and experimental (cid:29)ights with the x8 Skywalker UAV are used to test
the navigation system.
Keywords: Unmanned Aerial Vehicle, Real-Time Kinematic GPS, Inertial Navi-
gation, Nonlinear Observer
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Sammendrag
(Norwegian Translation of the Abstract)
Real-TimeKinematicGPSkangiposisjonsm(cid:229)lingermedcentimeternłyaktighetog
kanbrukestilsv(cid:230)rtnłyaktigposisjoneringavubemannedeluftfartły,ogs(cid:229)referert
til som droner. For at en GPS-mottaker skal kunne beregne sin egen posisjon m(cid:229)
den prosesserer satellitm(cid:229)linger som fłrer til en forsinkelse fra m(cid:229)letidspunktet til
posisjonsm(cid:229)lingen er tilgjengelig for dronen. Dersom dronen beveger seg i hły
hastighet, vil dette fłre til at posisjonsm(cid:229)lingen er utdatert n(cid:229)r den ankommer
dronen og fłrer til redusert nłyaktighet.
Denne masteroppgaven presenterer hardware- og softwarearkitekturen til et inte-
grert Real-Kinematic GPS/Treghetsnavigasjonssystem for ubemannede luftfartły
som kompenserer for denne tidsforsinkelsen. RTK GPS-systemet er konstruert
ved (cid:229) bruke to GPS-mottakere og Real-Time Kinematic Library (RTKLIB), et
(cid:229)pentkildekodebibliotekforsanntidsposisjonering. Navigasjonssystemeterimple-
mentert i DUNE: Uni(cid:28)ed Navigational Environment (DUNE)-rammeverket som
kjłres p(cid:229) en datamaskinen i nyttelasten til dronen. Integrasjonen av posisjons-
m(cid:229)linger og treghetsm(cid:229)linger utfłres av en uline(cid:230)r estimator som estimerer de
forsinkede tilstandene til dronen og predikerer de n(cid:229)v(cid:230)rende tilstandene ved hjelp
treghetsm(cid:229)linger. Hardware-in-the-Loopsimuleringerogeksperimentelle(cid:29)yvninger
er utfłrt for (cid:229) teste navigasjonssystemet.
Nłkkelord: Ubemannetluftfartły,Real-TimeKinematicGPS,Treghetsnavigasjon,
Uline(cid:230)r estimator
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Preface
This thesis is submitted in partial ful(cid:28)llment of the requirements for the degree
MSc. at the Norwegian University of Science and Technology. The initiative of
thisthesiscamefromtheAutonomousUAVprojectattheCenterforAutonomous
Marine Operations and Systems (AMOS).
I would like to thank my supervisor Professor Thor I. Fossen for his guidance and
feedback. Iwouldalsoliketothankmyco-supervisors;NadiaSokolovaforvaluable
feedback on RTK matters and Jakob Mahler Hansen for excellent comments and
productive discussions.
A huge thanks goes to Joªo Fortuna and Kristian Klausen for their invaluable
help at the Unmanned Aerial Vehicles Laboratory (UAV-Lab). Furthermore I
wanttothanktheUAV-pilotLarsSembforexcellent(cid:29)yinginduringexperimental
testing and the technical sta(cid:27) at the electronics and mechanical workshops at the
Department of Engineering Cybernetics for all their help.
Lastly I want to thank my family and girlfriend for their never-ending support.
Trondheim, June 18, 2015
Bjłrn Amstrup Spockeli
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