Realizing Dexterous Motions of Robotic Fingers with Spherical Rigid-Tips

This paper addresses a principle of linear superposition for realizing dexterous motions of a pair of dual multiDOF robotic fingers with spherical rigid tips during manipulation of an object. Firstly, sensory feedback control algorithms to (1) realize specified contact forces between the finger-tips and object surfaces and (2) regulate a rotational angle of the object to a given set-point value are proposed for a pair of dual 2-DOF robotic fingers. Secondly, a pair of dual 3-DOF robotic fingers is concerned in order to increase versatility and dexterity of object manipulation. Sensory feedback control inputs for regulating position of the mass center of the object in the reference coordinate frame are proposed. Principle of superposition is applied to design general control inputs for realizing stable grasping and regulating both the orientation of the object and its mass center position. Computer simulation work is carried out to evaluate effectiveness of the proposed control algorithms through examining performances of the contact forces, the rotational angle of the object, and the position of object’s mass center in two cases: (1) the desired rotational angle of the object is a pre-specified set-point value and (2) the desired rotational angle of the object is a periodic function.