Rotational Skin Stretch Feedback: A Wearable Haptic Display for Motion.

We present a wearable haptic feedback device that imparts rotational skin stretch to the hairy skin, along with the results of psychophysical tests to determine its resolution and accuracy for motion display. Tracking experiments with visual markers reveal the pattern of skin motion and strain imparted by the device, confirming subjective impressions that the design represents a trade-off between perception at low stimulus levels and comfort at maximum stimulus levels. In an isolated environment, users were able to discriminate between different rotational displacements of stretch within two to five degrees, depending on the reference stimulus. In a more realistic setting, subjects were able to use feedback from the device to control the positioning of a virtual object within six degrees or ±6.5 degrees of the total range of motion. When subjects were passive and exposed to arbitrary rotations of the device, the accuracy was poorer, although it improved with training. The results suggest that wearable skin stretch devices can be an effective means of providing feedback about a user's controlled joint or limb motions for motion training and similar applications.