Push resistance in in-hand manipulation

Haptic perception plays an important role in human life. It provides comprehensive information about the world, especially in in-hand manipulation tasks. For human the in-hand manipulation is an easy work; for robots it is still a challenge. One of its issues lies in the uncertainty of the interaction state. This paper researches robot object interaction from a novel angle, the method is called haptic exploration, which helps robots acquire the ability to explore the object in hand. For in-hand manipulation task, the haptic exploration is a process where the robot hand perceives contact force feedback from slightly push along different directions. In order to describe the force feedback, two definitions are given: pushable direction and push resistance. Additionally, a single finger push model and spatial multi-finger push model are proposed to illustrate push resistance. Furthermore an object push strategy is presented to reduce the number of push directions. At last real robot experiments are conducted to verify the proposed models. And its result also shows the feasibility of haptic exploration method.