Vibration-induced Friction Modulation to Enable Controlled Sliding for In-hand Manipulation

Abstract

Achieving controlled sliding of objects on finger surfaces is a significant challenge for robots, substantially constraining their ability to perform complex in-hand manipulation tasks. In this work, we investigate the role of surface vibration in modulating the effective friction at the object-finger contact locations to facilitate controlled sliding. We demonstrate that friction at contact points can be reduced by applying targeted vibrations at specific locations on a robotic finger, creating regions that are suitable for sliding. In this way, we create sticking/sliding regions on finger surfaces on demand and can easily switch between sliding and rolling contacts. To investigate this phenomenon, we embedded an array of vibration modules into robotic fingers. We first analyzed the velocity fields created by surface vibrations on a single finger. Then, we developed a method to select the appropriate activation states of the modules that achieve the desired velocity field at a given object location. Utilizing these fingers and the vibration selection method, we formed a two-finger robotic hand and demonstrated controlled sliding and rotation of a held object within the hand. To the best of our knowledge, this is the first work that utilizes vibration-induced friction modulation for in-hand manipulation that can achieve combinations of object sliding and rolling actions.