Design and locomotion analysis of a novel modular rolling robot

Abstract

Abstract This paper proposes a novel morphological modular robot that is capable of switching multiple directions and rolling locomotion. The mechanism of the robot resembles a spherical grid and it composes of 6 node modules and 12 planar RRR chain modules. The mobility of the mechanism is analyzed based on screw theory, and a kinematic model with 6° of freedom is obtained. The full kinematics including forward, inverse kinematics, Jacobian matrix and singularity analysis are presented to demonstrate the motion and deformation characters of the robot. The rolling locomotion of the robot can be realized by deforming its shape to change the center of gravity. In order to guarantee a stable rolling locomotion, a mathematical model and a control algorithm for rolling the robot as a planar mechanism are presented. The robot can be used to carry some payload such as a battery or camera at its center via a tension system of spring cables. The influence of the payload on the rolling locomotion of the robot is analyzed. Finally, the modules were manufactured and a prototype robot was assembled, and the deformation and rolling locomotion experiments were conducted to validate the design of the robot.