Dynamics of a rolling robot of closed five-arc-shaped-bar linkage

A morphological rolling robot of closed five-arc-shaped-bar linkage is presented. The rolling locomotion of the robot can effectively be propelled by morphing the shape of the robot to shift its center of gravity and forming surface-compliant configuration. Herein, we present the mechanical structure of the robot, kinematics modeling, and then dynamics of the rolling robot is analyzed with Lagrange's equation to obtain the generalized forces. Besides, the joint paths confined by rolling constraints are generated with the optimal principle of minimal module between the joint position and the reference joint trajectory. Then four schemes of dynamic rolling motion laws are presented with the purpose of comparison, and the simulation results show that the sinusoid motion law is more suitable for the dynamic rolling of the robot, due to the non-sharp transition in the rolling path and also the relatively small velocities and accelerations of the joints. Furthermore, dynamic rolling experiments on the prototype are used to verify the proposed concept and the results show that the dynamic rolling locomotion of this robot has favorable characteristics in speed, compliance and continuity.