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The human hand is very sensitive to the high-frequency accelerations produced by tool contact with a hard object, yet most time delayed telerobots neglect this feedback band entirely in order to achieve stability. We present a control architecture that both incorporates this important information and provides the ability to scale and shape it independently of the low-frequency force feedback. Leveraging the clean power flows afforded by wave variables, this augmented controller preserves the passivity of any environment that it renders to the user, but is not subject to the limitations of being passive itself. This architecture guarantees stability in the presence of communication delay while achieving a level of feedback not possible with a passive controller. We show experimentally that this feedback augmentation and shaping can present a high-frequency acceleration profile to the user's hand that is similar to that experienced by the slave end effector. Two simple user studies also show that the feedback augmentation improves the user's perception, performance, and confidence with the given tasks. We anticipate that these natural haptic cues will make teleoperative systems easier to use and thus more widely applicable.
Date of Publication: April 2006