Game Development Reference
In-Depth Information
Tactile rendering can be viewed from two angles: either as an interface that helps
to reproduce “gross'' tactile information, or as a communication interface. In teleop-
eration or virtual reality applications, tactile rendering proves to be useful because it
helps to restore relevant information related to the environment where one is operating,
whether it is synthetic or real, or even remote.
In these applications the interface aspect takes precedence over the communication
aspect because the tactile rendering must retranscribe the exact gross tactile informa-
tion, i.e. as felt by a direct contact. In the applications concerning the handicapped, the
communication aspect takes precedence over the interface aspect because here, it is a
question of restoring communicating information by substituting an absent modality
(the view for the visually handicapped, acceleration for patients suffering from equilib-
rium problem, etc.) by tactile information. In these applications, the “tactile language''
aspect is more important than the interface. One may wonder as to how to design an
interface that is useful to both, without it requiring a technology that would let go of
the developed concepts.
This chapter presents specific interfaces with cutaneous sensitivity, i.e. interfaces
that only get tactile stimuli, with low-intensity forces distributed on the body parts.
Note that any force feedback interface (with high intensity) automatically creates der-
mal sensations in addition to force. But in the latter interfaces, the dermal sensations
are only a result of the applied force and cannot be controlled directly. These cuta-
neous sensitivity interfaces can be used in isolation or with force feedback systems, but
the latter case involves the problem of mixing of the mechanical forces. These devices
mainly concern the hand, and are thus also a part of all the manual interfaces.
The absence of cutaneous sensitivity in a virtual world takes away a source of informa-
tion that can cause a problem for certain virtual simulations. The cutaneous sensitivity
of the person can be used wisely in spite of the difficulties and the small number of
commercial offers for this type of interface. We can distinguish between two tactile
interface functionalities:
The interfaces with tactile feedback inform the user about the mechanical effects
of the contact: Contact force intensities and sliding on the contact surface;
The interfaces with tactile feedback help the user to better interpret the superficial
aspect of the object: its local form from the surface, its material and superficial
Onemaywonder about the utility of such interfaces. Inwhat type of application are
the cutaneous sensitivity interfaces useful, or even indispensable? In the applications
of virtual reality, where at the level of the functional I 2 , 1 one of the objectives of the
application is to recognise an object from a group of objects. It is quite preferable
1 We use I 2 for Immersion and Interaction of the subject in the virtual environment
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