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    Mobile Robot Navigation

    Andersen, Jens Christian; Ravn, Ole; Andersen, Nils Axel

    Publication date:2007

    Document VersionPublisher's PDF, also known as Version of record

    Link back to DTU Orbit

    Citation (APA):Andersen, J. C., Ravn, O., & Andersen, N. A. (2007). Mobile Robot Navigation.

    http://orbit.dtu.dk/en/publications/mobile-robot-navigation(79104a01-7308-413e-8d20-7424c03fc13b).html

  • Jens Christian Andersen

    Mobile Robot Navigation

    PhD thesis, September 2006

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  • Technical University of Denmark

    Mobile Robot Navigation

    PhD thesisJens Christian Andersen

    September 2006

    Supervisors: Associate Professor Ole Ravn,Associate Professor Nils A. Andersenboth at Automation rstedDTU

    ISBN: 87-91184-64-9

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  • Preface

    This thesis is submitted in partial fulfilment of the requirements for thePhD degree at the Technical University of Denmark. The work was performedin the period March 2003September 2006 at Automation rstedDTU .

    The supervisors have been Associate Professor Ole Ravn and AssociateProfessor Nils A. Andersen both Automation rstedDTU.

    Working with robots is an inspiring, satisfactory occupation and a constantsource of enjoyment. Especially I remember a small event where a class ofabout 10-year-old pupils visited our lab. I gave a short demonstration of a fewof our robots, and one of the boys asked with wide open eyes: Is this a sort ofplayground for adults? And when I confirmed with a smile, he replied: Thisis where I want to go when I get older.

    I would like to thank both supervisors for the cooperation and encourage-ments in the project period and for the gentle pushes especially in situationswhere details became prohibitive for progress.

    Additionally I would like to thank the other members of the robotics groupfor the many informal discussions which have been a source of inspirationthroughout the years, and to the service-minded workshop for assistance andideas with the mechanical, electronic and logistic issues when needed.

    A special thank to Lisbeth Winter for her (patient) proofreading assistanceduring the writing of this thesis.

    And finally: this project would never have been possible without the supportand encouragement from my beloved family: my wife Birte and my son Mikkel.

    Kgs. Lyngby, September 2006

    J. Christian Andersen

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  • Abstract

    Robots will soon take part in everyones daily life. In industrial productionthis has been the case for many years, but up to now the use of mobile robotshas been limited to a few and isolated applications like lawn mowing, surveil-lance, agricultural production and military applications. The research is nowprogressing towards autonomous robots which will be able to assist us in ourdaily life. One of the enabling technologies is navigation, and navigation is thesubject of this thesis.

    Navigation of an autonomous robot is concerned with the ability of therobot to direct itself from the current position to a desired destination. Thisthesis present and experimentally validates solutions for road classification,obstacle avoidance and mission execution. The road classification is based onlaser scanner measurements and supported at longer ranges by vision. The roadclassification is sufficiently sensitive to separate the road from flat roadsides,and to distinguish asphalt roads from gravelled roads. The vision-based roaddetection uses a combination of chromaticity and edge detection to outline thetraversable part of the road based on a laser scanner classified sample area.

    The perception of these two sensors are utilised by a path planner to allowa number of drive modes, and especially the ability to follow road edges areinvestigated.

    The navigation mission is controlled by a script language. The navigationscript controls route sequencing, junction detection, junction crossing calcula-tions and drive mode selection.

    The entire system is tested on a combination of narrow asphalt and gravelledroads connected by a number of junctions. Missions of up to 3 km in lengthhave been successfully completed using the described system.

    The main focus of the thesis has been the experimental validation of theimplemented solutions and the ability of the methods to solve real world prob-lems.

    The amount of software needed by an autonomous robot can be overwhelm-ing. Software reuse and distributed development are therefore important issues.The thesis describes a new component architecture for robotics software thatpromotes software reuse and distributed development and maintenance.

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  • Dansk Resume

    Robotter vil om fa ar blive en del af vores daglige liv. Inden for pro-duktionsindustrien har det allerede vre tilfldet i mange ar, men anven-delsen af mobile robotter har hidtil vret henvist til isolerede omrader somgrsslaning, overvagning, landbrugsproduktion og militre funktioner. Frem-skridt i forskningen der gr, at robotter vil kunne assistere os i mange af voredaglige gremal i en ikke safjern fremtid. En af de teknologier, der skal gredette muligt, er navigation, og navigation er emnet for denne afhandling.

    Navigation for autonome robotter handler om robottens evne til autonomtat manvrere fra den nuvrende position til et nsket bestemmelsessted. Denneafhandling prsenterer og validerer eksperimentelt lsninger til detektering affarbar vej, omgaelse af forhindringer og gennemfrelse af missioner. Vejklassi-fikationen er baseret pa laserscanner malinger og assisteret med vision for ln-gere rkkevidde. Vejklassifikationen er tilstrkkelig selektiv til at kunne ad-skille selv flade vejrabatter fra selve vejen og kan isolere asfaltveje fra grusveje.Vejgenkendelse ud fra kamera billeder tager udgangspunkt i klassifikationenfra laserscanneren og bruger en kombination af farve og kantdetektering til atestimere farbar vej pa lngere afstande.

    Resultatet af disse to sensorer anvendes under planlgning af en farbar rute,og her er det isr robottens evne til at flge vejens kanter, der er undersgt.

    Navigationen i en mission er styret af et sekventielt manuskript. Manuskr-iptsproget giver mulighed for detektering af vejkryds, for beregninger til brugunder passagen af disse kryds og til valg a styringsmetode ivrigt.

    Det samlede system er testet pa en kombination af asfalt- og grusveje, medet antal forgreninger og vejkryds. Missioner pa op til 3 km lngde er gen-nemkrt autonomt med det beskrevne system.

    Fokus i afhandlingen har vret den eksperimentelle validering af de im-plementerede metoder og metodernes evne til at lse problemer i en virkeligeverden.

    Der skal en betydelig mngde software til for at styre en autonom robot, em-ner som software genbrug og distribueret udvikling er derfor essentielle. Denneafhandling beskriver yderligere en komponentbaseret arkitektur for robotter,som kan fremme software genbrug og distribueret udvikling og vedligeholdelse.

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  • Contents

    1 Introduction 17

    1.1 State of the art . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

    1.2 Unsolved aspects . . . . . . . . . . . . . . . . . . . . . . . . . . 20

    1.3 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

    1.4 Navigation disciplines . . . . . . . . . . . . . . . . . . . . . . . . 23

    1.5 Navigation platform elements . . . . . . . . . . . . . . . . . . . 24

    1.6 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

    1.7 Thesis structure . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

    2 Overview 27

    2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

    2.2 Robot conceptual model . . . . . . . . . . . . . . . . . . . . . . 27

    2.3 Task breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

    2.3.1 Behaviour generation . . . . . . . . . . . . . . . . . . . . 29

    2.3.2 World model and value judgement . . . . . . . . . . . . . 30

    2.3.3 Sensor processing . . . . . . . . . . . . . . . . . . . . . . 31

    2.4 Experimental platform . . . . . . . . . . . . . . . . . . . . . . . 32

    2.4.1 Mechanical capabilities . . . . . . . . . . . . . . . . . . . 32

    2.4.2 Posture detector . . . . . . . . . . . . . . . . . . . . . . 33

    2.4.3 GPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

    2.4.4 Laser scanner . . . . . . . . . . . . . . . . . . . . . . . . 35

    2.4.5 Camera . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

    2.4.6 Computer . . . . . . . . . . . . . . . . . . . . . . . . . . 36

    2.4.7 Security . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

    2.5 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

    2.5.1 Road navigation . . . . . . . . . . . . . . . . . . . . . . . 37

    2.5.2 Vision support . . . . . . . . . . . . . . . . . . . . . . . 38

    2.

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