Tactor-Induced Skin Stretch as a Sensory Substitution Method in Teleoperated Palpation

When we use a tool to explore or manipulate an object, friction between the surface of the tool and the fingerpads generates skin stretch cues that are related to the interaction forces between the tool and the object. In this study, we emulate these naturally occurring skin stretch cues in order to convey force direction and magnitude information to users during teleoperation. We hypothesize that skin stretch feedback is a useful substitute for kinesthetic force feedback in force-sensitive teleoperated tasks. In this study, ten participants performed teleoperated palpation to determine the orientation of a stiff region in a surrounding artificial tissue using five feedback conditions: skin stretch, force, reduced gain force, graphic, and vibration. When participants received skin stretch feedback, they localized the stiff region as well as with force feedback, with no increase in task completion time. Additionally, participants receiving skin-stretch feedback localized the stiff region statistically significantly more accurately than those using vibration feedback. Although participants using skin stretch exhibited higher interaction forces than when using force, vibration, and graphical feedback, skin stretch statistically significantly decreased interaction forces compared with reduced gain force feedback. Thus, skin-stretch feedback is a compelling substitute for force feedback and may be useful in scenarios where force feedback is reduced or infeasible.