Modeling and control of the coordinated motion of a group of autonomous mobile robots

Abstract

BIR GRUP OTONOM MOBIL ROBOTUNKOORDINELI HAREKETININ MODELLENMESI VE KONTROLUNusrettin GULECOzetBir grup otonom mobil robotun, verilen bir gorevi basarmak icin koordinelihareketi son on yilda onemli bir arastirma konusu olmustur. Robotlarin engellerleve grubun diger elemanlariyla carpismalarinin engellenmesi onceki calismalarin dagosterdigi gibi, bu alandaki en temel problemlerden biridir. Onemli miktarda aras-tirma cabasi koordineli davranis icindeki bir grup otonom mobil robot icin refer-ans yorungeler ortaya koyacak sanal kuvvetler tanimlama yonunde yogunlasmistir.Eger mobil robotlar holonom degillerse, holonom olmama kisitlamasi yanal yondekihareketi engelleyecegi icin, bu yaklasim koordineli hareketi kesin olarak saglamaya-bilir. Bu tez calismasinda bir grup otonom holonom olmayan mobil robotun ko-ordineli hareketini modelleme ve kontrol etme problemine, yeni bir carpisma en-gelleme algoritmasi da iceren, iki yeni yaklasim gelistirilmistir. Birinci yaklasimda,cevrimici carpismasiz yorungeler ortaya koyacak sanal kutle-yay-amortisor birim-lerinden olusan bir sanal referans model kullanilarak, otonom holonom olmayanmobil robotlar icin yeni bir koordinasyon metodu gelistirilmistir. Ikinci yaklasimdaise, robotlar icin cevrimici referans yorungeler dogrusal ve acisal hizlari cinsindenolusturulmustur. Ayrica, onerilen iki modelde de bir carpisma ongoruldugu zamanrobotlarin hizlarini guncelleyen yeni bir carpisma engelleme algoritmasi gelistirilmis-tir. Bazi koordineli gorev orneklerinin sunulmasiyla birlikte, onerilen modeller ben-zetimlerle dogrulanmistir. Carpisma engelleme algoritmasinin performansinin dog-rulanmasi icin deneyler yapilmistir.

MODELING AND CONTROL OF THE COORDINATED MOTIONOF A GROUP OF AUTONOMOUS MOBILE ROBOTSNusrettin GULECAbstractThe coordinated motion of a group of autonomous mobile robots for the achieve-ment of a coordinated task has received signiï¬cant research interest in the lastdecade. Avoiding the collisions of the robots with the obstacles and other mem-bers of the group is one of the main problems in the area as previous studies haverevealed. Substantial amount of research eï¬ort has been concentrated on deï¬ningvirtual forces that will yield reference trajectories for a group of autonomous mobilerobots engaged in coordinated behavior. If the mobile robots are nonholonomic, thisapproach fails to guarantee coordinated motion since the nonholonomic constraintblocks sideway motions. Two novel approaches to the problem of modeling coordi-nated motion of a group of autonomous nonholonomic mobile robots inclusive of anew collision avoidance scheme are developed in this thesis. In the ï¬rst approach, anovel coordination method for a group of autonomous nonholonomic mobile robotsis developed by the introduction of a virtual reference system, which in turn impliesonline collision-free trajectories and consists of virtual mass-spring-damper units.In the latter, online generation of reference trajectories for the robots is enabled interms of their linear and angular velocities. Moreover, a novel collision avoidancealgorithm, that updates the velocities of the robots when a collision is predicted,is developed in both of the proposed models. Along with the presentation of sev-eral coordinated task examples, the proposed models are veriï¬ed via simulations.Experiments were conducted to verify the performance of the collision avoidancealgorithm.