MODELING AND CONTROL OF THE COORDINATED MOTION OF A GROUP OF AUTONOMOUS MOBILE ROBOTS by NUSRETTIN GULEC

The coordinated motion of a group of autonomous mobile robots for the achievement of a coordinated task has received significant research interest in the last decade. Avoiding the collisions of the robots with the obstacles and other members of the group is one of the main problems in the area as previous studies have revealed. Substantial amount of research effort has been concentrated on defining virtual forces that will yield reference trajectories for a group of autonomous mobile robots engaged in coordinated behavior. If the mobile robots are nonholonomic, this approach fails to guarantee coordinated motion since the nonholonomic constraint blocks sideway motions. Two novel approaches to the problem of modeling coordinated motion of a group of autonomous nonholonomic mobile robots inclusive of a new collision avoidance scheme are developed in this thesis. In the first approach, a novel coordination method for a group of autonomous nonholonomic mobile robots is developed by the introduction of a virtual reference system, which in turn implies online collision-free trajectories and consists of virtual mass-spring-damper units. In the latter, online generation of reference trajectories for the robots is enabled in terms of their linear and angular velocities. Moreover, a novel collision avoidance algorithm, 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 several coordinated task examples, the proposed models are verified via simulations. Experiments were conducted to verify the performance of the collision avoidance algorithm. BIR GRUP OTONOM MOBIL ROBOTUN KOORDINELI HAREKETININ MODELLENMESI VE KONTROLU