Fig. 7
From: Friction perception resulting from laterally vibrotactile stimuli
Temporal course of simulated friction forces caused by vibrotactile stimuli. Top When \(\dot{x}_f = 0.1\) m/s and \(\dot{x}_r(t) > 0\) constantly apply. Bottom When \(\dot{x}_f = 0.04\) m/s and \(\dot{x}_r(t)\) can be zero. For stimuli #3 and #4, the simulated friction forces are not continuous because the direction of the friction force is not always the same as that of the finger velocity