Inverse kinematics and workspace analysis of the metamorphic hand

Abstract

This paper investigates for the first time inverse kinematics of a four-fingered metamorphic hand. Compared with the current existing robotic hands, the most significant feature of the metamorphic hand is the introduction of a foldable and reconfigurable palm and its function of metamorphism, which greatly improves the ability of posture adjustment and inter-coordination between fingers. Geometric constraints of the palm are analyzed by using geometric method and constraint equation method, on the basis of which, kinematics of the metamorphic hand are transformed from a hybrid mechanism into serial mechanisms and forward kinematics can be obtained directly. To avoid the complexity of inverse kinematics of the thumb, a method taking advantage of geometric constraints of the palm is introduced to simplify the inverse kinematics of the metamorphic hand and analytical solutions are obtained in a concise form. The workspace of the metamorphic hand is decomposed into palm workspace and finger workspace. A triangle determined by the mounting points is introduced to measure the palm workspace and the simulation of the finger workspace augmented by the palm reveals that the reconfigurable palm contributes tremendously to the flexibility and versatility of the metamorphic hand.