Three-dimensional object manipulation by two robot fingers with soft tips and minimum D.O.F

This paper shows through faithfully deriving Paffian forms of 3D rolling contact constraints that 3D pinching can be stabilized by using a pair of robot fingers with a hemispherical soft tip and minimum degrees of freedom under the gravity effect. The proposed control input is based on fingers-thumb opposition without using object information or external sensing. Stability analysis of the closed-loop dynamics is presented by using a Lyapunov method. Finally, for the sake of confirmation of effectiveness of the proposed control signals, numerical simulations are carried out.