Biomedical Engineering Reference
In-Depth Information
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(a)
(b)
Figure 8.11
Upper and lower jaws are touching two different objects (with softnesses of 30 and
10 Shore A). The objects are located in parallel. (a) Tactile image display. (b) Photograph of the
grasper and elastomers
with a harder material. Finally, in Figure 8.13, sensors
U
4
and
L
2
are in touch with a soft
material while other sensors are in touch with a harder material.
8.3 Graphical Representation of a Lump
For the lump detection algorithm, another tactile sensor, as introduced in Chapter 4, was
used. The teletaction system used for the experiment consisted of this tactile sensor, a
DAQ card and its electronics, and the necessary signal-processing algorithms in order
to process the information from the sensor to the display. The tactile sensor (PVDF
film) measured the pressure across the seven sensing elements (1.5 mm width spaced
0.5 mm apart). Each sensor in the PVDF array produced an analog voltage output as
a result of the forces applied by the object. The electrical outputs of the piezoelectric
sensing elements were then conditioned and transmitted to the DAQ system. A ren-
dering algorithm, developed in LabVIEW, was used to map the extracted features of
the signal to a grayscale image. By observing these constructed images, the surgeon is
able to determine whether or not a lump is present and, if it is, its approximate size
and location.
