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Abstract: Stable User-Specific Haptic Rendering of the Virtual Wall
Stable User-Specific Haptic Rendering of the Virtual Wall
by
R. Brent Gillespie
and
M. R. Cutkosky
Proceedings of the 1996 International Mechanical Engineering Congress
and Exhibition, Atlanta, GA, DSC Vol. 58, pp. 397-406
© 1996 ASME.
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from the American Society of Mechanical Engineers.
Abstract:
Efficient control algorithms are developed to implement stiff virtual
walls without chatter. An analysis of the complete coupled system
comprising controller, interface device, and user's finger underlies
the design of a wall algorithm, thus each virtual wall is tailored to
a specific user impedance. The finger is modeled as a static second
order impedance with justification drawn from empirical studies of
limb dynamics available in the literature and from observations of the
disparity in time scales between contact instability and volitional
control. Compensation is incorporated for the destabilizing effects
of the zero order hold using either model based prediction or design
in the digital domain. The destabilizing effects of asynchronous wall
on/off switching times and sampling times are tracked by a special
watchdog while deadbeat control is used to periodically eliminate
these effects. Extensions are discussed, including on-the-fly system
identification of the user impedance.
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