Back-to-back skin stretch feedback for communicating five degree-of-freedom direction cues

This paper presents the design and development of a novel device for providing tactile feedback in five degrees of freedom (5-DOF). Four translational and four rotational motions of the hand can be communicated to a user using two independently controlled 2-DOF skin stretch feedback devices placed back-to-back. An additional two rotational motions of the hand can be communicated through spiral motions of the two skin stretch feedback devices. The user´s index finger and thumb grasp the device at the location of the moving contactor (tactor) of each of the 2-DOF skin stretch displays, respectively. Experiments show user responses to have high directional accuracy (> 98%) for each of the five degrees of freedom communicated by the device. A second experiment also shows a proof of concept for using the back-to-back skin stretch display to guide users´ hand motions to match a specified target angle in a one degree-of-freedom wrist rotation task. Findings from this preliminary study will be used in future studies to investigate users´ ability to track paths in multiple degrees of freedom or to direct the hand motions of a user, which could be relevant to tasks such as upper limb rehabilitation, swing training, or other motion training.