The nature of human prehension: Three dextrous hands in one

The human hand is versatile in its interactions with the environment, demonstrating skills that designers of dextrous robot hands would like to emulate. From the many attempts that have been made to understand the use of the human hand and to establish classifications of prehensile activity, common themes emerge. Two key issues seem to be balanced in prehensile tasks: that of affixing the object in the hand, and that of gathering information about the state of the object during the task. In this paper, we show these being balanced through combinations of three basic methods of applying oppositions around obiects, and we show how these relate to the postures of standard prehensile classifications.