HaptiCeiling: An Encountered-type Overhead Haptic Interface in Virtual Reality

Environmental haptic interfaces have been extensively researched for their ability to enhance spatial realism, diversity, and immersion in Virtual Reality (VR). Among these, the Overhead Haptic Interface (OHI) has shown unique interaction opportunities in VR, such as space design, training, and entertainment. However, direct touch interaction with encountered-type OHI and users' perceptual abilities in these contexts remain underexplored. In this paper, we introduce HaptiCeiling, an OHI utilizing a parallel mechanical system driven by three linear actuators. The system allows translational motion along the z-axis from 0 to $450 m m$ and angular motion from −30 degrees to 30 degrees around both x and y-axes, enabling the rendering of various OHIs in VR. Through three user studies, we explored (1) just-noticeable difference (JND) in perceiving changes of HaptiCeiling's height and tilt angle, (2) the perceptual thresholds for virtual overhead interface height and tilt angle compared to HaptiCeiling without causing any semantic violations, and (3) the perceived realism and immersion of our system across three VR applications.