Mid-Air Haptic Algorithms for Rendering 3D Shapes

Mid-air haptic technology works by focusing ultrasonic radiation pressures onto the user’s bare hands, thereby delivering a localized vibrotactile effect. Advanced spatial and temporal modulation of the focused pressures expands the haptic capabilities of this technology and can enable the rendering of volumetric shapes. To that end, we explore ten different algorithms for the haptic rendering of virtual 3D objects and describe their respective implementations, weight their pros and cons, and discuss their applicability in different settings and paradigms. The two best performing algorithms are then user-tested to assess their applicability. We conclude that salient features, and especially object corners, should be emphasized by the mid-air haptic rendering algorithms when shape information is important and provide easy to follow guidelines. We also note that the visual representations of haptified objects can pre-condition our haptic expectations. We thus propose alternative graphic representations in order to mitigate such discordance.