Texture compensation for haptic feedback signal compression
Recently proposed haptic offline compression algorithms remove perceptually irrelevant haptic samples to achieve data reduction. At display-time, the irregularly subsampled haptic signal is resampled at a higher constant sampling rate using interpolation. Such algorithms, however, have an important drawback. Although they are well suited for large-amplitude quasi-static feedback forces, low-amplitude high-frequency texture information is adversely affected. This informative tactile high-frequency component, critical to convey convincing realistic haptic impressions, needs to be treated separately for compression. To this end, we extract important tactile elements crucial to texture perception from the haptic signal in the time domain and propose a method to encode them so that the overall storage requirements are minimized. We then synthesize and superimpose them onto the reconstructed signal at display-time. Psychophysical tests confirm that the proposed approach significantly improves the texture assessment quality during playback, while reducing storage space requirements by up to 97%.