A New Control Strategy for the Improvement of Contact Rendering with Encounter-type Haptic Displays
Résumé
Encounter-type haptic interfaces are used to interact physically with virtual environments. They allow controlling the position of an avatar in the simulation while perceiving the forces applied on it when it interacts with the surrounding objects. Contrary to usual force feedback devices, the interface tracks the real user’s finger without touching it when the user’s finger avatar moves in free space. Only when a contact occurs in the virtual environment, the interface comes in contact with the user to display the mechanical properties of the encountered objects. This way, the device’s behaviour is more natural as simulated contacts really occur in the real world. Existing control laws for such devices exhibit however limitations, especially when contacts occur at high speed. In such cases, the device tends to bounce against the user’s finger, which decreases the realism of the interaction. In this paper, we propose a new control strategy where the interface is first stabilized again st the obstacles before the user touches its end-effector. This way, contacts appear more natural, even at high speeds, as confirmed by preliminary user-tests made with an existing 2 DoF encounter type haptic interface at different speeds with the state of the art control law and the novel approach we propose here.
Domaines
Automatique / Robotique
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