Mälardalen University Licentiate Thesis 288 Lan Anh Trinh Dependable Path Planning For DEPENDABLE PLANNING PATH FOR AUTONOMOUS CONTROL Autonomous Control Lan Anh Trinh Address: P.O. Box 883, SE-721 23 Västerås. Sweden ISBN 978-91-7485-451-0 2019 Address: P.O. Box 325, SE-631 05 Eskilstuna. Sweden E-mail: [email protected] Web: www.mdh.se ISSN 1651-9256 1 Mälardalen University Press Licentiate Theses No. 288 DEPENDABLE PATH PLANNING FOR AUTONOMOUS CONTROL Lan Anh Trinh 2019 School of Innovation, Design and Engineering 2 Copyright © Lan Anh Trinh, 2019 ISBN 978-91-7485-451-0 ISSN 1651-9256 Printed by E-Print AB, Stockholm, Sweden 3 To my family. 4 Acknowledgments I would like to express my thanks to many persons who have directly and indi- rectly helped me on the path that leads to this dissertation. First and foremost, I especially thank my supervisors, Professor Dr. Mikael Ekstrom¨ and Dr. Baran Cur¨ ukl¨ u,¨ who have guided and supported my research with warm encourage- ment and insightful advice. I also thank for their great helps in life so that I can understand more about Swedish culture, overcome all difficulties, settle down and feel that Sweden is my second mother land. I also especially thank all MDH gangs, PhD students in Malardalen Uni- versity, who are very good, friendly, and enthusiastic. Even though we do not communicate much, you guys always give me nice advices when needed. Many thanks to all of my friends in Robotics Group, who have been always very nice and friendly teammates, Fredrik, Carl, and others, especially two my office-mates Gita and Branko, who have helped me a lots in both researches and life. Many next thanks to DPAC leaders who have proposed an excellent project so that I have learnt a lots and enjoyed working within the project. I am always thankful to administrative ladies who have made all the complicated administrative procedures to become easy and smooth. Last but not least, I would like to especially thank my family in Vietnam, my husband, and my little Sam for their unconditional supports, endless love, and encouragement. They are my accompany at every stage in my educa- tion and life. They are the ones I can always share the burden of stress. My motivation is also contributed by the love from them and their belief for this iv 5 v dissertation. I want to dedicate this thesis to them whom I love most in my life. Lan Anh Trinh Vaster¨ as,˚ December, 2019 6 7 Sammanfattning Att byta fran˚ automatisk till autonom kontroll har visat sig vara ett av de vik- tigaste teknikskiften vid utvecklingen av robotar idag. Den autonoma kon- trollen gor¨ det mojligt¨ for¨ en robot att ha mer frihet samt mojlighet¨ till di- rekt interaktion med manniskor¨ och andra robotar. Att ha en palitlig˚ plattform for¨ autonom kontroll blir daavg˚ orande¨ nar¨ vid byggandet av ett sadant˚ sys- tem. Tillforlitligheten¨ hos en robotagent representeras av ett antal huvudat- tribut sasom˚ tillganglighet,¨ dvs systemets kontinuerliga drift over¨ ett tidsinter- vall, tillforlitlighet,¨ dvs systemets form¨ aga˚ att tillhandahalla˚ korrekta tjanster,¨ och sakerhet,¨ dvs. robotagenten maste˚ sakerst¨ alla¨ sakra¨ kontroller for¨ att und- vika katastrofala konsekvenser for¨ anvandare,¨ andra robotar och slutligen miljon.¨ Med tanke paatt˚ banplanering ar¨ en av nyckelkomponenterna i ett autonomt kontrollsystem for¨ robotagenter, syftar arbetena som presenteras i denna avhan- dling att bygga en palitlig,˚ dvs saker,¨ palitlig˚ och effektiv banplaneringsal- goritm for¨ en grupp robotar som delar sitt arbetsutrymme med manniskor.¨ For¨ det forsta¨ foresl¨ as˚ en ny metod for¨ banplanering av flera robotagenter baserat padipolfl˚ odesf¨ alt.¨ For¨ att initialisera vagarna¨ fran˚ en startpunkt till ett mal˚ anvands¨ banplanering med Theta* - algoritmen for¨ en uppsattning¨ av agenter. For¨ att hantera statiska hinder for¨ en robot som ar¨ pav˚ ag¨ till malet˚ definieras ett statiskt flodesf¨ alt¨ langs¨ den konfigurerade banan. Ett dipolfalt¨ beraknas¨ sedan for¨ att undvika kollision med andra agenter och personer. I detta tillvagag¨ angss˚ att¨ antas varje robotagent vara en kalla¨ till ett magnetiskt dipolfalt,¨ i vilket det magnetiska momentet ar¨ riktat i agentens rorelseriktning,¨ vii 8 viii med en styrka som ar¨ proportionell mot dess hastighet. De magnetiska dipol- dipolinteraktionerna mellan dessa agenter genererar darepulsiva˚ krafter for¨ att hjalpa¨ dem att undvika kollision. Samtidigt anvands¨ felanalys med Petri-nat¨ av flera robotar for¨ att forst¨ asamarbetet˚ mellan flera robotagenter for¨ att losa¨ de gemensamma uppgifterna. Darefter¨ appliceras Petri-natet¨ tillsammans med vagplaneringen¨ for¨ att undvika kollisioner genom synkroniserade rorelser¨ hos robotar genom exempelvis en korsning. Under tiden har kontinuerligt flervags-¨ planering undersokts¨ for¨ att stodja¨ feltoleransen for¨ sokplaneringsalgoritmen.¨ Detta for¨ att hantera dodl¨ aget¨ dar¨ agenten tar mycket lang˚ tid att nam˚ alet˚ eller till och med inte kan gora¨ det. Agenten har forsetts¨ med olika planer- ade vagar¨ till malet˚ och vaxlar¨ proaktivt mellan dessa nar¨ det behovs¨ for¨ att undvika dodl¨ aget.¨ Slutligen har hela ramverket implementerats i en allmant¨ anvand¨ plattform, robotoperativsystem (ROS), och utvarderats¨ genom Gazebo- simulator. 9 Abstract Changing from automatic to autonomous control has emerged as the main shift on the development of robots nowadays. The autonomous control allows robot to have more freedom as well as direct interactions with human and other robots. Having a dependable platform for autonomous control becomes crucial when building such a system. The dependability of a robotic agent is presented by main attributes including availability, i.e. the continuous operations of the system over a time interval, reliability, i.e. the ability of the system to provide correct services, and safety, i.e. the robotic agent must ensure safe controls to avoid any catastrophic consequences on users, other robots, and finally the environment. Considering path planning is one of the key components of an autonomous control system for robotic agents, the works presented in this the- sis aim at building a dependable, i.e. safe, reliable and effective, path planning algorithm for a group of robots that share their working space with humans. Firstly, the method for path planning of multiple robotic agents is proposed based on a novel dipole flow field idea. The any angle-path planning with Theta* algorithm is employed to initialise the paths from a starting point to a goal for a set of agents. To deal with static obstacles while a robot is going on the way to its goal, a static flow field along the configured path is defined. A dipole field is then calculated to avoid the collision of agents with the other agents and human subjects. In this approach, each robotic agent is assumed to be a source of a magnetic dipole field in which the magnetic moment is aligned with the moving direction of the agent, with a strength proportional the ix 10 x velocity. The magnetic dipole-dipole interactions between these agents gen- erate repulsive forces to help them to avoid collision. Meanwhile, the fault analysis of multiple robots with Petri net is demonstrated to understand the cooperation of multiple robotic agents to solve the shared tasks. Thereafter, the Petri net is applied together with the path planning to address the collision avoidance by synchronising the movement of robots through a cross. Continu- ously, the multiple path planning has investigated to support fault tolerance for the path planning algorithm. This is to deal with the deadlock situation where the agent takes very long time to reach the goal or even is not able to do so. The agent is equipped with different paths to the goal and proactively switch among the plans whenever needed to avoid the deadlock. Finally, the whole framework has been implemented by a widely used platform, robot operating system (ROS), and evaluated through Gazebo simulator. 11 List of Publications Papers Included in the Licentiate Thesis1 Paper A Fault Tolerant Analysis for Dependable Autonomous Agents Using Colored Time Petri Nets Authors: Lan Anh Trinh, Baran Cur¨ ukl¨ u,¨ Mikael Ekstrom¨ Status: Published in 9th International Conference on Agents and Artificial In- telligence, ICAART 2017. Paper B Toward Shared Working Space of Human and Robotics Agents Through Dipole Flow Field for Dependable Path Planning Authors: Lan Anh Trinh, Mikael Ekstrom,¨ Baran Cur¨ ukl¨ u¨ Status: Published in Frontiers in Neurorobotics, volume 12, May 2018. Paper C Petri Net Based Navigation Planning with Dipole Field and Dy- namic Window Approach for Collision Avoidance Authors: Lan Anh Trinh, Mikael Ekstrom,¨ Baran Cur¨ ukl¨ u¨ Status: Published in 6th International Conference on Control, Decision and Information Technologies, CODIT 2019. Paper D Multi-Path Planning for Autonomous Navigation of Multiple Robots in a Shared Workspace with Humans 1The included papers have been reformatted to comply with the thesis layout xi 12 xii Authors: Lan Anh Trinh, Mikael Ekstrom,¨ Baran Cur¨ ukl¨ u¨ Status: Submitted. 13 xiii Additional Peer-Reviewed Publications, not Included in the Licentiate Thesis • ”Dipole Flow Field for Dependable Path Planning of Multiple Agents”. Lan Anh Trinh, Mikael Ekstrom,¨ Baran Cur¨ ukl¨ u.¨ Workshop on Shared Autonomoy, IEEE/RSJ International Conference on Intelligent Robots and Systems, 2017. • ”Failure Analysis for Adaptive Autonomous Agents using Petri Nets”. Mirgita Frasheri, Lan Anh Trinh, Baran Cur¨ ukl¨ u,¨ Mikael Ekstrom.¨ The 11th International Workshop on Multi-Agent Systems and Simulation (MAS&S’17). • ”Dependability for Autonomous Control with a Probability Approach”. Lan Anh Trinh, Baran Cur¨ ukl¨ u,¨ Mikael Ekstrom.¨ Newsletter in ERCIM News 109, Autonomous Vehicles. 14 15 Contents I Thesis 1 1 Introduction 3 2 Backgrounds 7 2.1 DEPENDABILITY AND PETRI NET . .7 2.1.1 Dependability . .7 2.1.2 Petri nets . 10 2.2 PATH PLANNING AND THETA* . 11 2.3 DYNAMIC WINDOW APPROACH . 14 3 Related Works 17 3.1 DEPENDABILITY FOR AUTONOMOUS CONTROL .