Biomedical Engineering Reference
In-Depth Information
FIGURE 7-27
McGill University
STReSS tactile
display. [Adapted
from (Pasquero
2003)], with
permission.
FIGURE 7-28
Vibrotactile haptic
device. (Becker,
Jang et al., 2009.)
Larger tactile devices are also made for the torso or limbs where the density of sensory
corpuscles is much lower. A number of these devices are shown in Figure 7-29. They are
often made from micromotors driving an eccentric mass, similar to those commonly
found in portable consumer equipment like phones and PDAs. They are therefore very
low cost. The vibration frequency is proportional to the applied voltage, and can therefore
be controlled. Unfortunately, the response time is poor.
Alternative designs are based on the construction methods for earphones where the
diaphragm is replaced by a spring support with a central contactor pin.
7.7.2.3 Construction of Vibrotactile Devices
A trade-off is required between the minimum force, and hence displacement, of the pins
of a vibrotactile device to ensure that each one registers even after desensitization and a
