Experimental Study of Motion of the Mobile Robots Moving in the Convoy Type Formation

Abstract

In this paper the authors describe the experiment, which consists in studying the motion of the mobile robots moving in the convoy type formation, including one leader-robot and several follower-robots. The components of the educational robots and their sensor devices including Hokuyo urg-04lx-urg01 scanning laser rangefinder (only the leader-robot has it) are introduced. A distributed control system of the robots in ROS (Robot Operating System) is described, at the same time the functions of each node of the robots are presented in detail. The authors describe the SLAM algorithm of the leader-robot and its computational process in practice, and simultaneously the algorithm of the trajectory planning in real-time is described briefly. The authors present the PID controller for DC (direct current) motors and discuss the performance of DC motor according to its step response in the loading conditions. The motion control algorithm of the follower-robot is also presented. Experimental results including the map of environment and the trajectory of robots on the map are provided, which demonstrate effectiveness of the used algorithms. The authors analyze the reasons for discrepancy in the trajectories of some robots in a group, for example, different positioning accuracy of the leader-robot and follower-robots, delays in communication, insufficient performance of the actuator. The further research direction consists of two aspects: firstly, the coordinated movements of the drone and a group of mobile robots moving in the convoy type formation; secondly, logical control of a group of robots when changing the formation topology. The control mechanism ensured the execution of various convoy behaviors, for example, convoy separation.