In-hand manipulation using a 3-PRS-finger-based parallel dexterous hand with bidirectional pinching capability

Abstract

Considering the defects of the traditional dexterous hand in precise in-hand manipulation and bidirectional pinching capability, this paper proposes a 3-PRS-finger-based parallel dexterous hand (PDH). The PDH structure is composed of three 3-PRS parallel fingers. First, a pinching shape analysis is conducted to demonstrate the PDH's bidirectional pinching capability. Then, by analyzing the workspace of the PDH pinching nine objects, the influence on the in-hand manipulation workspace of different objects is determined. The PDH can perform symmetrical in-hand manipulation to address the issue that almost all humanoid dexterous hands pinch objects in a single direction. The force transmission capability of the PDH is compared with that of the 3R serial dexterous hand (SDH) under the same trajectory. The results indicate that the PDH have the possibility to possess a good pinching force performance through the specific trajectory planning. Bidirectional pinching experiments are conducted, and the experimental results demonstrate that the PDH can realize the accurate in-hand manipulation under almost frictionless conditions. The proposed PDH provides a feasible design for the theoretical development and practical application of dexterous hands.