Passive haptics: Variable asperity by using damping brake of DC motor

A passive haptic interface that is inherently safe and stable and can present variable virtual asperity was developed. This interface delivers passive resistance force by switching on and off the damping brake of a DC motor without being driven. We conducted identification experiments for six levels of asperity stimuli to investigate human perceptual properties against passive asperity. Variable asperity was found to be successfully discriminated into several levels at approximately 70%. Furthermore, information transfer was calculated to be 1.60 bits.