Mapping synergies from human to robotic hands with dissimilar kinematics: an object based approach

Robotic hands differ in kinematics, dynamics, programming, control and sensing frameworks. Their common character is redundancy, which undoubtedly represents a key feature for dexterity and flexibility, but it is also a drawback for integrated automation since it typically requires additional efforts to seamlessly integrate devices, particularly robotic hands, in industrial scenario. This paper focuses on the mapping between hands with dissimilar kinematics. It is based on the argument that the reflected optimality of the pattern of grasping forces emerging from human hand synergies should be matched, in some sense, by the sought for postural synergies of robotic hands. As a natural consequence of the proposed approach, postural synergies for different kinematic structures could look entirely different in geometric shape. This difference should be a consequence of aspects such as different dimensions, kinematic structures, number of fingers, compliance, contact properties which cannot come into play if a gross geometric mapping is applied. The proposed mapping is based on the use of a virtual sphere and will be mediated by a model of an anthropomorphic robotic hand able to capture the idea of synergies in human hands.