The Sixth-Finger: A modular extra-finger to enhance human hand capabilities

Abstract

Robotic prosthesis are usually intended as artificial device extensions replacing a missing part of a human body. A new approach regarding robotic limbs is presented here. A modular robot is used not only for replacing a missing part of the body but also as an extra-limb in order to enhance manipulation dexterity and enlarge the workspace of human beings. In this work, the model and control of an additional finger, the Sixth-Finger, is presented as a case study of this type of robotic limbs. The robotic finger has been placed on the wrist opposite to the hand palm. This solution allows to enlarge the hand workspace, increasing the grasp capability of the user. An object-based mapping algorithm is proposed to control the robotic extra-finger by interpreting the whole hand motion in grasping action. A four DoFs modular prototype is presented along with numerical simulations and real experiments. The proposed Sixth-Finger can lead to a wide range of applications in the direction of augmenting human capabilities through wearable robotics

Modification of body schema by use of extra robotic thumb

“…That have been studied to increase grasping range and ability to perform activities with one hand [13]. They have been also studied to help the recovery of stroke patients with somatosensory feedback [14] and without it [15].…”

Grand Challenges in Shape-Changing Interface Research

“…Many examples of external augmentation come from the robotics community (e.g. prosthesis or the sixth finger device [71]) to enhance manipulation dexterity. Conversely, smart fabric can change its stiffness around the user's joints to restrict their movement in gaming, training, or rehabilitation [1].…”

Soft wearable assistive robotics: exosuits and supernumerary limbs

“…However, even after extensive therapeutic interventions in acute rehabilitation, the probability of regaining functional use of the impaired hand is low [59]. For this reason, we recently started studying robotic devices for the compensation of hand function in chronic stroke patients, and in [60,61,62] we introduced a wearable robotic extra finger that can be used as an active compensatory tool for grasping objects.…”