Why the State of the Art Matters: The Importance of Functional Abstraction in Robot Hand Design

Abstract

Despite 40 years of research in the field of robotic hands, the reproduction of human capabilities for dexterous manipulation still seems far to be achieved by state-of-the-art technologies. From a design perspective, even defining what are the “optimal functionalities” of a robotic hand is a very challenging task due to the number of different requirements in terms of degrees of freedom, force, speed, compactness, robustness and so on. In the specific fields of humanoid robotics and prosthetics, the robotic hand is expected to provide high flexibility and adaptability, ideally replicating the overall functionality of the human hand. The general perception, however, is that current robotic hands able to provide (even limited) human-like dexterity and functionalities are either too complex and expensive or too bulky and unreliable to truly represent effective solutions for the market, limiting their usage to research labs. A closer look to the specific aspects involved in the development of a robotic hand shows that, even if the mechanical structure of the device is somehow inspired by the biological counterpart, a large range of solutions can be found for the implementation of joints, actuators and sensors, but none of those represents “the” solution to the specific problem. Also from the point of view of control algorithms and user interfaces, the actual scenario is quite controversial, since the use of current robotic hands is in some way largely limited by the difficulties in task planning, problem that is sometimes amplified by the limited portability of the solutions developed for a specific hand to the others. The result is that only very specialized and well-trained experts can effectively use a specific robotic hand exploiting its full potential, while the generalization and the standardization of the robotic hand control problem is still a serious issue.