Biomedical Engineering Reference
In-Depth Information
60
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40
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10
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Angle (degrees)
(a)
40
20
0
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(b)
0.8
0.6
0.4
0.2
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(c)
(a) The force - angle curve, energy, and steepness measured at 40
◦
, (b) energy, and
Figure 5.16
(c) steepness
This shows that the result of applying the criteria is independent of the angle to which
the criteria are applied. Finally Figure 5.16 shows the force - angle curves of four silicone
rubber samples.
Figure 5.16b,c shows the energy and steepness of the curves; it is still possible to use
them to arrange the softness of the silicones.
As mentioned, the proposed system comprises an endoscopic grasper equipped with
force sensors, a potentiometer for measuring the jaw angle, and a signal processing unit.
It is shown that this system can, potentially, be used for softness characterization of the
grasped tissue in laparoscopic surgery.
The experiment results show that for the soft materials, the transferred force from the
grasper to the material is sinusoidal. As the material becomes harder, the pressure wave-
form changes from sinusoidal to pulse. Also it can be concluded that for harder materials,
the load applied to the object becomes larger. Finally, using the force - angle graphs plot-
ted for the test materials, it is shown that the grasped materials can be discriminated from
each other based on their softness.
