Haptic Exploration During Fast Video Playback: Vibrotactile Support for Event Search in Robot Operation Videos

Fast playback allows quick video exploration, but it also decreases the saliency of short events. We propose a haptic exploration for detection of short events during fast video playback, considering that event-related information in vibrotactile feedback can be preserved during fast playback using Time Scale Modification (TSM) methods developed for audio. We evaluate our proposal in two collision detection experiments using first-person view (FPV) videos. In the first experiment, viewers watched at a fixed playback speed, i.e.,
$1\times$
or
$2\times$
, videos recorded with a camera mounted on a platform cart. In this experiment, event-related vibrations were measured at the back of the camera. In the second experiment, viewers used a media controller to adjust the playback speed in videos simulating an exploration with a mobile robot. In this experiment, event-related vibrations were generated from the measurements used in the first experiment. We show that a haptic exploration improves collision awareness under either constant or adjustable playback speed. In both experiments, the number of collisions reported without vibrotactile feedback deviated the greatest from the actual number of collisions in a video. Moreover, collision detection performance with vibrations time-scaled without Time Scale Modification (TSM) methods was not significantly different from performance without vibrations.