Locomotion of two vibration-driven modules connected by a mechanical position limiter

Abstract

The dynamics of a new kind of vibration-driven system with two modules connected by a mechanical position limiter under isotropic dry friction is studied in this paper. To this end, the dynamical equations of the two-module system are established and simplified based on the properties of the position limiter, which is a passive component but plays an important part in the motion of the system in cooperation with the specific motion control on the internal masses. The motion control of the system is built on a two-phase acceleration control, which consists of two uniformly variable motions of the internal mass. The driving force generated from the internal mass overcomes the dry friction for forward motion but does not exceed the friction force for backward motion, thus an always-forward motion is found. Some discussions on the motion are taken to optimize the driving parameters and show some good properties and limitations of the system. Afterwards, an experimental prototype is designed to show the motion capability of the system. The prototype succeeds in imitating the motion of the system and demonstrating the importance of the position limiter during the motion qualitatively although still needs to be improved in the future.