Pinching at Fingertips for Humanoid Robot Hand

Delicate actions such as picking up paper or a needle with the fingertips – an important function for robot hands – are extremely difficult. We propose a lightweight robot hand based on extracting minimum required motor functions and implementing them in a robot. We also propose a robot hand that realizes appropriate pinching by adding the minimum required degree of supplementary freedom realizable only mechanically. In the robot hand, we focus mainly on adding degrees of freedom for independent finger motion to the terminal joints and a degree of freedom for twisting by the thumb. The results showed that providing the fingertip with a joint with broad force control even with weak force effectively ensures delicate fingertip control in a humanoid robot hand.