Game Development Reference
to the interface. This section gives some examples of interfaces that help to have
surfaces in the 3D real world.
Hirota and Hirose (1995) are interested in the concept of universal surface to
obtain haptic rendering. One of the results obtained is an interface made up of two
parts. The first is completely passive with 2 DOF. It helps to track the finger movement.
The second, consisting of 4
4 pins, is arranged on a square surface with side 20mm.
Each rod has a 50mm stroke, and the combination of the various rods helps to display
to the user the form of the surface being explored.
The Institute of Engineering Mechanics and Systems, of the University of Tsukuba,
developed FEELEX (Iwata et al., 1997). This interface includes a flexible screen, actu-
ators and a projector. The size of the screen is 24
24 cm 2 . It is connected to linear
actuators that deform its flat surface. Each linear actuator consists of a screw mech-
anism run by a DC motor. This mechanism converts the rotation of an axis of the
motor into a linear movement of a rod. The diameter of the motors is 4 cm. A 6
linear actuator matrix can thus be placed under the screen. The deformable screen
is made of a rubber layer and white nylon material. The thickness of the rubber
Another interface has been developed in the NIBH in Japan, by the Shinohara
team (Shimojo et al., 1999). Its purpose is to present three-dimensional forms to the
user by raising and lowering spikes. These spikes, which are maintained in a vertical
direction using two horizontal planes which act as guides, translate along this vertical
axis under the action of a display object (a sphere) that moves on the horizontal plane.
10.4.2.5 Braille interfaces for the visually impaired
In the context of industrial applications for tactile rendering, one of the most promising
domains is that of interfaces for assistance to the handicapped. The Braille language
that is based on tactile exploration is used by a certain number of visually impaired
persons. Several Braille systems are marketed.
In the case of the DM80 Braille interface marketed by BAUM, the content of the
screen is read by means of 80 piezoelectric tactile elements (with 8 points forming
Braille rectangles) that are fast and reliable.
The RBD (Refreshable Braille Display) Braille interface generates Braille by raising
and lowering pins, in response to an electronic signal. The RBD interface, available
in the market, consists of piezoelectric element-based actuators. Currently, the main
disadvantage of this product is its sale price (approx. $5000 for 40 cells). The Rotating-
Wheel Based Refreshable Braille Display is an innovative device that constitutes an
interesting attempt to reduce costs. The principle of this device is to turn the Braille
cells under the reader's fingertips in a way that only a few holes of these cells that
turn need to be actuated at a given moment. The main advantage of such a structure
is the reduced number of motorised actuators. This device has been developed by the
National Institute of Standards and Technology.
The Vincent Hayward team proposed a new concept called VBD (Virtual Braille
Display) in order to reduce costs of the Braille interfaces. The interface is based on a
stack of 12 lead zirconate titanate layers with a thickness of 0.38mm. The maximum
deformation (without load) is 0.5mm and the frequency can reach 500Hz. The whole
unit is placed on a translation axis with one degree of freedom. Tactile illusions that