Discriminability of Virtual Roughness Presented by a Passive Haptic Interface

A passive haptic interface based on the damping brake of a DC motor was used to present surface roughness. Virtual roughness stimuli were expressed by using periodic resistance forces caused by switching the damping brake on and offat regular intervals. We investigated the ability of humans to discriminate such roughness stim uli through information transfer and signal detection theory. Our results revealed that the passive haptic interface can present three to four levels of roughness stimuli without confusion, which is slightly inferior to an active-type haptic interface.