This thesis is submitted to the School of Computing at Blekinge Institute of Technology in partial fulfillment of the requirements for the degree of Master of Science in Computer Science. The thesis is equivalent to 20 weeks of full time studies. Master’s Thesis Computer Science Thesis no: MCS-2013-10 Month Year Collision Detection and Overtaking Using Artificial Potential Fields in Car Racing game TORCS using Multi-Agent based Architecture Muhammad Salman [email protected] [email protected] Contact Information: Author: Muhammad Salman Address: Lindblomsvägen 98 LGH 1205 , 372 33 Ronneby Sweden E-mail: [email protected] University advisor(s): Dr. Stefan J. Johansson, PhD School of Computing Blekinge Institute of Technology School of Computing Internet : www.bth.se/com Blekinge Institute of Technology Phone : +46 455 38 50 00 SE – 371 79 Karlskrona Fax : +46 455 38 50 57 Sweden ABSTRACT The Car Racing competition platform is used for evaluating different car control solutions under competitive conditions [1]. These competitions are organized as part of the IEEE Congress on Evolutionary Computation (CEC) and Computational Intelligence and Games Sym-posium (CIG). The goal is to learn and develop a controller for a car in the TORCS open source racing game [2]. Oussama Khatib [3] (1986) introduced Artificial potential fields (APFs) for the first time while looking for new ways to avoid obstacles for manipulators and mobile robots in real time. In car racing games a novel combination of artificial potential fields as the major control paradigm for car controls in a multi-agent system is being used to coordinate control interests in different scenarios [1]. Here we extend the work of Uusitalo and Stefan J. Johansson by introducing effective collision detection, overtaking maneuvers, run time evaluation and detailed analysis of the track using the concept of multi-agent artificial potential fields MAPFs. The results of our extended car controller in terms of lap time, number of damages and position in the race is improved. Keywords: Artificial Potential Fields, TORCS, Simulated Car Racing Championship, Collision Detection, Overtaking 1 ACKNOWLEDGMENTS “In the name of God Almighty, the Beneficent, the Merciful” I would like to thank my supervisor Dr. Stefan J. Johansson, who was very kind and supportive during my thesis work. He has been a great help and support on the way to my findings. I will always look forward to work under his kind supervision in the future. I would also like to thank my parents for their prayers and support during my long stay outside the country. I would also like to thank the developers behind the open racing car simulator (TORCS) for providing such a wonderful platform to test AI concepts and techniques., the star up tutorial written by Bernard Way man to develop a controller bot in TORCS. The last acknowledgement goes to the organizers of the simulated car racing championship. They developed a client server based module to TORCS in a rather complex but challenging environment. 2 Contents ABSTRACT .......................................................................................................................................... 1 ACKNOWLEDGMENTS .................................................................................................................... 2 1 INTRODUCTION ....................................................................................................................... 7 1.1 TORCS .................................................................................................................................. 7 1.2 SIMULATED CAR RACING CHAMPIONSHIP ............................................................................. 8 1.3 MOTIVATION ....................................................................................................................... 10 1.4 THESIS STRUCTURE .............................................................................................................. 10 2 RELATED WORK .................................................................................................................... 11 3 RESEARCH QUESTION AND HYPOTHESIS ..................................................................... 12 3.1 RESEARCH QUESTIONS ........................................................................................................ 12 3.2 AIMS AND OBJECTIVES ........................................................................................................ 12 3.3 HYPOTHESIS ........................................................................................................................ 12 3.3.1 Path Finding and Navigation.......................................................................................... 13 3.3.2 Fields of Curvature ......................................................................................................... 13 3.3.3 Collision Detection ......................................................................................................... 13 3.3.4 Overtaking ...................................................................................................................... 13 3.3.5 Keep the car on track ...................................................................................................... 13 3.4 VERIFICATION OF HYPOTHESIS ............................................................................................ 13 4 METHODOLOGY .................................................................................................................... 14 4.1 ARTIFICIAL POTENTIAL FIELDS ............................................................................................ 14 4.2 MULTI-AGENT POTENTIAL FIELDS ...................................................................................... 15 4.3 THE IDENTIFICATION OF OBJECTS ......................................................................................... 16 4.4 MOTIVATING FORCES IN TORCS ......................................................................................... 16 4.5 OBJECTS ASSIGNMENT TO DIFFERENT FIELDS ...................................................................... 17 4.6 THE GRANULARITY OF TIME AND SPACE .............................................................................. 17 4.7 MAS ARCHITECTURE .......................................................................................................... 18 5 STRATEGIES AND TECHNIQUES ....................................................................................... 19 5.1 TRACK ................................................................................................................................. 19 5.1.1 Track View (TORCS) ...................................................................................................... 19 5.1.2 Track Sensors (Simulated Car Racing Championship) .................................................. 19 5.2 LOOKAHEAD POINTS ............................................................................................................ 20 5.2.1 Determine the length of lookahead points ...................................................................... 21 5.3 THE AGENTS ........................................................................................................................ 22 5.3.1 Driver Agent ................................................................................................................... 22 5.3.2 Track Agent ..................................................................................................................... 22 5.3.3 Curvature Agent .............................................................................................................. 24 5.3.4 Speed Agent .................................................................................................................... 25 5.3.5 Overtaking Agent ............................................................................................................ 26 5.3.6 Traction Control Agent ................................................................................................... 27 5.3.7 The Interface Agent ......................................................................................................... 28 5.3.8 Track Analysis Agent ...................................................................................................... 28 5.3.9 Determine left/right placement of latitude position ........................................................ 28 6 EXPERIMENTS ........................................................................................................................ 30 6.1 BRIEF DESCRIPTION OF THE OPPONENTS ............................................................................... 30 6.1.1 Autopia ............................................................................................................................ 30 6.1.2 Olethros .......................................................................................................................... 31 6.1.3 Inferno, Lilliaw and dammned ........................................................................................ 31 6.2 THE TRACKS ........................................................................................................................ 31 6.3 PREPARATION ...................................................................................................................... 33 6.4 EXPERIMENT 1 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