Page 72 - Flexible Robotics in Medicine

56 Chapter 3

Figure 3.8
Results for the bending capability test.

Figure 3.9
The maneuverability of the optical zooming segment: (A) t 5 n, (B) t 5 n 1 1 (front segment
contracted to avoid the obstacle), (C) t 5 n 1 2 (front segment extended), and (D) t 5 n 1 3
(obstacle is displaced).

concentric workspace provides the prototype with more path selection in order to mediate
obstacles, in addition to its ability to provide mechanical zooming.

3.4.4 Finite element analysis

Finite element analysis is a method used to analyze the prototype by subjecting the prototype to
deformations, pressure, forces, and stresses to determine the weakest point in the prototype.
After identifying the weakest point of the prototype, we can perform further analysis to
determine the threshold of the weakest point, to assess if the weakest point is able to withstand
the mechanical stresses and forces of the physiological conditions within the human body.
For the FlexDiamond, the weakest point is predicted to be the edges of the diamond cuts. The
stresses experienced at these sharp edges should be the highest, and hence render it most
vulnerable when inserted into the subject for endoscopy. The thickness of the bending segment,
which housed four holes that were cut along the bending segment, may also experience high
shear stresses when the cables are manipulated to bend the endoscope. The cables may cut
through the walls of the endoscope due to the low shear modulus of the fabrication material.
Finite element analysis needs to be conducted to determine the weakest point of the prototype
design accurately. After the analysis, revisions of the prototype design might be needed to