Game Development Reference
location tracking tasks (Patrick et al., 1990) and in the improvement of response time
(Akamatsu, 1994), in the absence or presence of poor visual conditions (Massimino &
Sheridan, 1993). The presence or absence of a tactile sensation thus necessarily has an
impact on the immersion felt by the VE users. While the dexterity of the tactile sense
in vibratory mode is crucial to determine the texture of an object, it is also valid to
determine the vibratory information per se.
The detection of vibrations has been the objective of some works, like those pre-
sented in (Kontarinis & Howe, 1995). The authors demonstrated that, in the presence
of high-vibration frequencies, it is possible to increase the performance of certain tests
by reducing the response time and minimising the applied force. The tactile sense is
also important to detect the initiation of the contact. Massimino and Sheridan (1993)
showed that tactile rendering helps to obtain significant performances to detect small
force amplitudes in the establishment phases of the contact. InHowe (1992), the author
has shown that tactile feedback is a necessary supplement to force feedback when min-
imum force is required, for example, in high-precision manipulations. In addition, the
tactile sense can support several discriminative activities that the proprioceptive sense
(by force feedback) cannot support. The tactile sense is more enhanced than the pro-
prioceptive sense. It is actually used to determine the local form and texture of objects.
It can also obtain information regarding compliance, elasticity, viscosity and electrical
and thermal conductivity of objects.
There are several possible ways to classify tactile interfaces based on the actuation
technology, architecture and fields of application. A state-of-the-art on the existing
tactile stimulators, their physical, spatial and frequency features will be presented in
the following part of this chapter. Please note that a classification based on the fields
of application has been selected. The following are the main fields from amongst the
existing fields of application that could be identified:
Teleoperation and telepresence;
Studies carried out on the various parameters of the tactile sense;
3D surface generation;
Braille display systems;
10.4.1 Tactile stimulation technologies
Tactile stimulation can be accomplished in various ways. The technologies used for
virtual environment systems first borrowed the technology of the matrix printers or
Braille display systems for the visually handicapped. We then find solutions based on
mechanical pointers activated by electromagnetic technologies (solenoids, vibrating
membranes or Voice Coils 2 ), piezoelectric elements, shape memory alloys 3 , pneumatic
systems and heat pump systems based on the Peltier effect. A description of the var-
ious technologies along with the advantages and disadvantages of each of them is
2 Voice Coil: English name of the actuator of a loudspeaker or audio coil.
3 Shape memory alloys have been referred to as AMF.