High-speed and energy-efficient locomotion of a seed-like underactuated robot on level surface by utilizing asymmetric wobbling effects

It was clarified that forward locomotion of a seed-like robot on level road surface can be obtained by adding a 2-DOF active wobbling mass. This paper improves the velocity and efficiency of the robot by utilizing 1-DOF wobbling mass with asymmetric wobbling effects. First, we develope the mathematical model and generate the rotation motion of the underactuated robot by applying asymmetric torque. Second, the rotation is efficiently utilized to move forward by introducing asymmetric friction. The robot therefore achieves high-speed locomotion like a seal crawling on the beach. Third, the nonlinear dynamics is analyzed from the synchronization point of view. Finally, we check whether the motor efficiency is increased by our proposed methods. Better than previous studies, the 1-DOF underactuation at the ground-contact point is passively controlled by our proposed methods.