Dynamic Object-Transportation Control Method by Multiple Mobile Robots

This paper proposes a dynamic control method to transfer a common object by the coordination of multiple wheeled mobile robots. The coupler which comprises an active prismatic joint and a passive rotary one is installed on each robot so that even the mobile robot with non-holonomy can correctly manipulate the object. The coordinative control system composed of a leader and other staff robots is designed to perform the accurate and high-speed object transportation based on the synchronous motions of the robots under their dynamical interactions. The leader robot successively defines the desired acceleration of the object to move along its target trajectory, and broadcasts the information to the staff robots. Each staff robot controls the motions of its own body and the on-board prismatic joint so as to achieve the desired acceleration of the object. When the prismatic joint approaches its mechanical limit, the staff robot requests to modify the desired acceleration of the object to the leader. The control algorithm is formulated on the basis of the kinematics and the dynamics of both the object and the robot. The simulation results for the transportation of an object by four mobile robots illustrate the validity of the proposed coordinative control method.