In-hand Manipulation with Fixed and Spring Support Fingers

Abstract

In-hand manipulation is one of distinctive skills in anthropomorphic hands. Lots of research has been done, however modeling the process of robotic in-hand manipulations is a challenging topic in robotics. In this paper, a novel in-hand manipulation model is proposed based on push and support fingers. In this model, we consider the in-hand manipulation process as a finger pushing an unknown object to roll onto other fingers, where only one finger is controlled actively to push the in-hand object. This actively controlled finger is called push finger. Moreover the support fingers also play important roles. Two kinds of support fingers are proposed in this model: fixed support finger and spring support finger. The fixed support finger is uncontrolled and fixed as a pivot around which the object rotates. The spring support finger performs as an elastic spring. It can not only press the object against other fingers to ensure the stability of the system but also can help to rotate the object with proper contact force. To achieve the spring-like attribute, a stiffness controller was applied on the spring support finger. At last, in-hand manipulation experiments have been carried out successfully on a real anthropomorphic hand platform to verify the feasibility of our proposed model. Although the object’s rotated angle is small in experiments, our proposed method has great potential in perceiving interaction state of the in-hand manipulation system.