The multifingered NAIST hand system for robot in-hand manipulation

This paper presents the mechanical design of a multifingered robotic hand referred to as the “NAIST hand.” The hand has a total of 12 degrees of freedom (DOFs) in four fingers. Each finger has a total of three DOFs where two DOF for the metacarpal phalangeal (MP) joint and one DOF for the proximal interphalangeal (PIP) joint; the distal interphalangeal (DIP) joint is coupled with the PIP joint. A novel three-axis gear driving mechanism that enables the placement of all three electrical motors that drive the finger joints in the palm region has been developed without the use of tendons. In addition, the mechanism requires less space for the actuators and reduces the burden on the motors in terms of finger-tip force generation. A direct teaching system that involves observation of the contact points between the operator’s fingertips and the instrumented object has been successfully implemented to reproduce dextrous in-hand manipulation using the NAIST hand.