Page 452 - Flexible Robotics in Medicine

446 Chapter 19

19.6.2.3 Drill tip vibration

To analyze the vibration generated by the drill, we measured the force fluctuations in the X
and Y directions since this is the plane that the drill bit spins in (Fig. 19.25). To quantify
the data, processing was done in MATLAB to estimate frequency and amplitude in each
direction. The amplitude in the graphs corresponds to the fluctuations in force.

The graphs and tabulated data are shown. The lower one indicate Y direction forces, while
the upper one indicate X direction forces (Fig. 19.26)(Table 19.5).

19.6.3 Animal cartilage

To further verify the Goldrill GR3’s viability, we tested drilling through pig cartilage
(Fig. 19. 27). This test was conducted within the constraints within the lumen of the PVC
tubing to simulate the curvature and lumen of the trachea.

The Goldrill GR3 was able to successfully drill through approximately 3 4 mm thick
cartilage at the end of the tubing. Pig cartilage is a more accurate simulation of the tracheal
rings, which is also composed of cartilage. Thus, being able to drill the tissue stably
successfully helps to lend credibility to our design. The full assembly demonstrated the
feasibility of a ratchet mechanism for stabilization and the quality of the design even in a
minimal dimension.

19.6.4 Comparison with gold finger

This test demonstrates the improved design of the Goldrill GR3 compared to the model that
inspired its design, the gold finger. This test was conducted by hanging various weights to
determine the force required to cause the segments to unhinge.
As demonstrated by the hanging weights as well as the previous segment bending
OptoForce test, the Goldrill GR3 can withstand more than 13 N of force, while the gold
finger segments break away at less than 150 g. This could be due to the gold finger not
being designed to withstand large amounts of force in the Z direction.
The Goldrill GR3 is a lightweight, compact, and portable device, weighing approximately 152 g.

19.7 Future developments

Current 3D printing technology enables us to print stainless steel directly from our 3D
model. Therefore, the ideal fabrication method of the Goldrill tube is to use the stainless
steel 3D printing procedure. The Goldrill GR3 should ideally be made of stainless surgical
steel instead of 3D-printed PLA material. Stainless steel is much stronger and rigid, which