A Multi-DoF Exoskeleton Haptic Device for the Grasping of a Compliant Object Adapting to a User's Motion Using Jamming Transitions

In the recently growing field of virtual reality, the virtual grasping sensation remains in its infancy, and the discrep- ancy between real and virtual grasping has become a problem. This article develops a new haptic glove that presents the sensation of different types of grasping (e.g., power/precision/intermediate grasping)acompliantobject.Tothisend,wedevelopanexoskeleton that fixes the movements of fingers to present a braking force and a flexible pad that reproduces a wide range of stiffness. By applying the “string jamming mechanism,” our exoskeleton has functions thatexistingdevicesdonot.Inthat,itconstrainsthemotionoffinger extension/flexion and adduction/abduction with only one actuator and presents the braking force to all surfaces of the finger. In addition, we propose a lightweight and compact variable-stiffness pad that reproduces an extensive stiffness range based on the layer jamming technique. We conducted experiments to evaluate the me- chanical performance of the prototype integrating the exoskeleton and the variable-stiffness pad and demonstrated the usefulness of the proposed glove.