Midair Haptic Display to Human Upper Body

In this paper, we present a calibration method for multi-unit midair haptic display that can cover a workspace larger than one-meter cube. In typical previous midair haptic displays, the workspace was smaller than a 30-cm cube, where the display target was limited to a hand and fingers. To achieve a large workspace covering a human upper body, we develop a system where arbitrarily located multiple display units with sensors can determine the relative positions and postures by a simple calibration process. In a prototype system using two units of 45 cm by 57 cm phased arrays, we examine the ultrasound convergence from the multiple units. We also show that the midair haptic stimulation is perceivable through clothes on the upper body.