Rendering spatiotemporal mid-air tactile patterns

Mid-air haptics is a recent ?eld concerned with conveying haptic feedback in midair to complement 3D interfaces which are already integrating gesture tracking or volumetric displays. While the community has mainly spent the last decade focusing on the technical challenges of developing a mid-air haptic display, little attention has been spent on haptic pattern-rendering techniques. The work presented here targets this last consideration and investigates the perceptual implications of varying the parameters of a recently developed rendering technique called spatiotemporal modulation. The technique aims at producing spatially distributed mid-air haptic patterns, by rapidly and repeatedly moving a tactile point along a given pattern path. However, it is unclear how the rendering parameters a?ect skin deformation and haptic perception. In addition, especially when two parameters are interdependent, it is unclear which should be optimised. In the ?rst study, I used vibrometry to compare the e?ects of pattern-rendering speed (i.e. the speed at which the tactile point moves along the pattern) and rendering rate (i.e. the rate at which a given pattern is repeated) on skin displacement. The study highlights the importance of rendering speed over rendering rate in maximising the skin displacement. A user study showed later that rendering speed also maximised pattern perceived strength, corroborating that increased displacement leads to increased perceived strength. A second user study investigated the importance of the pattern sampling rate (i.e. the sampling position number along a pattern) while rendering a given mid-air haptic pattern. The results show that decreasing the sampling rate enhanced the pattern strength, especially for patterns rendered at a rate of under 20Hz. These results also allow the unlocking of low rate stimuli that could not be perceived with the traditional sampling approach. In each of these studies, the discoveries are summarised in comprehensive guidelines, so designers can bene?t through an implementation of my results in their design of mid-air haptic patterns