Slack strategy for cable driven haptic interfaces
Résumé
Common haptic devices induce interaction with
users by transmitting direct forces, corresponding to a coupled
environment. Paradoxically, because of their intrinsic mechan-
ical limitations they struggle in cases where this last requires
null forces. Cable mechanism are investigated to improve
this situation thanks to their low structural inertia. However,
current control approaches on these interfaces implies that
all cables are always under tension. Consequently, the user is
permanently linked with the mechanism and is therefore subject
to friction and rotor inertia from actuators. He/She constantly
feels these parasites forces even during free exploration. As an
alternative, we propose to physically disconnect the user from
actuators by selectively slacking some cables when no forces are
required. The contact is rendered by ensuring that slack runs
out right at this moment. A pilot experiment tests the feasibility
of this new approach. Benefits and drawbacks on perception
are explored as well as consequences on movement. Beyond the
expected cancellation of vibrations and perceived inertia during
the free motion, results show a large improvement on velocity
performances. They also warn about a funnel effect on contact
due to shortcomings of the prediction of the point of collision.
Domaines
Sciences de l'ingénieur [physics]Origine | Fichiers produits par l'(les) auteur(s) |
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