Micromanipulation using micro hand with two rotational fingers

Abstract

An 8-DOF micro hand consisting of two rotational fingers is developed. Each finger has 4 DOF: 3-DOF translation of the fingertip driven by three linear stages and 1-DOF rotation about the finger’s cylindrical axis driven by one rotation stage. The finger is a glass rod attached to the rotation stage. The two fingers are tilted and placed on an inverted microscope’s stage from both sides of the objective lens. The fingertips cross each other and grasp an object above the objective lens. The fingers translate the grasped object spatially by moving in the same direction together. The fingers can also rotate the object about its two axes if the fingers move along their cylindrical axes in the opposite directions or rotate about their cylindrical axes. Because of the eccentricity of rotation, the finger cannot rotate exactly on its cylindrical axis only using the rotation stage. This error is cancelled by moving the three linear stages in the opposite directions to the error. Virtual stick method for manual operation of this micro hand is implemented. A human operator commands 3-DOF translation and 2-DOF rotation of the grasped object using a PHANTOM omni-device, as if the operator directly manipulates the stick which is virtually fixed to the center of the object. The commanded motion of the object is converted to the motions of the two fingers, which are inputs to the controllers of the fingers. The developed micro hand can grasp and translate a spherical soft object of about 120[μm] in diameter spatially by virtual stick method. The hand can also rotate the object about its two axes by virtual stick method.