Tactile-based torque illusion controlled by strain distributions on multi-finger contact

Humans experience torque when using a tool such as a stick or a stylus when exploring or manipulating an object. Forces that exert on the tool affects the pressure distribution on contact areas of the digits involved. In this paper we proposed a tactile rendering method that can elicit torque illusion by controlling the strain distribution beneath the contact areas. We assume that controlling the strain distribution on multiple fingers can affect strain energy density to a relative extent. Also, we expect that Merkel Disk response increases with the strain energy density. We control the strain distribution beneath the contact areas using a unique vacuum driven tactile interface. Six participants are requested to perform a psychophysical experiment and evaluate the torque sensation on the tactile interface. The device can move in a rotating frame with one degree of freedom. Experimental results suggest that participants felt an increasing torque sensation during strain redistribution. Point of subjective equality increases as much as 56% from lowest to highest stimuli level. This data shows an early confirmation on a method that can induce torque illusion.