Game Development Reference
Figure 12.14 Sarcos Treadport © University of Utah
rarely compatible with reduced size display configurations. A technique lets you
get around the problem by suggesting the user to walk in place (Usoh et al., 1999).
GAITER (Templeman Naval Research Labs) is a movement analysis system letting
the user move in the virtual environment by walking in place. The system records
the movements of his legs and determines the direction and speed of movement.
Treadmills: in order to compensate the problem of space while maintaining a more
realistic simulation than walking in place, the use of treadmills is proposed. In a
unidirectional case, these are treadmills similar to exercise treadmills 12.14(a)) The
subject stands and walks on the moving treadmill. Moreover, the Sarcos Tread-
port makes simulation of a gradient possible (12.14(b)). To simulate non-linear
movements, omnidirectional treadmills have also been developed.
Treadmills fitted with sensors: other techniques use a stationary treadmill fit-
ted with sensors like the VMC or Virtual Motion Controller (Hit Lab Univ.
Washington). The VMC is made of a curved working surface incorporating 4
weight sensors thanks to which the system determines the planned direction of the
user (12.15). The “Magic Carpet'' (Georgia Tech) is similar to the VMV. It is a
floor carpet covered with piezoelectric sensors that makes measuring the position
of the feet possible.
Another metaphor consists of using skills developed by the users regarding driving
vehicles. For this, we suggest the user to control his movement by using a driving cabin:
car driving cabin (12.16), cockpit or simply a bicycle 12.17(a) 12.17(b). The bicycle is
a simple means of capturing the intention to move using 3 degrees of freedom. It is used
for simulating a movement by pedalling and with the help of a direction command.
This technique makes force feedback possible through pedals and handlebars.
In spite of the inherent advantages of the previous solutions linked to their similarities
in relation to real movements, their usage is restrictive: big space, often expensive