Midair Hand Guidance by an Ultrasound Virtual Handrail

This paper attempts to verify that human subjects can move a hand along a virtual path produced by ultrasound without visual information. The path, from start to finish (the ‘goal’), is presented by switching ultrasound focal points. The movement of focal points produces vibrotactile stimuli on the hand, and users perceive it as a line. The users can move their hand to the goal by tracing this line. With our method, users actively trace the path, therefore no feedback of hand position is necessary. In the experiment, we verified that the participants can move their hand to the goal with a deviation of less than 50 mm. Also, the average deviation between the trajectory of the hand and a curved path is less than 40 mm. Thus, we concluded that users move their hand along the path while perceiving it.