Page 236 - Flexible Robotics in Medicine

224 Chapter 9

Figure 9.7
Through-hole manipulation in gelatin and its corresponding trajectory.

Table 9.2: Average deflection and the standard deviation of the distal drill.
Bending angle
(θ s ) 0 degree 80 degrees 160 degrees
Δx Δy Dis Δx Δy Dis Δx Δy Dis
Drill speed (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm)
LOW AVE 0.4 0.6 0.72 0.9 0.4 0.98 1.1 0.4 1.17
STD 0.55 0.42 0.56 1.09 0.54 1.18 0.89 0.55 0.97
MEDIUM AVE 0.8 0.7 1.06 1 0.5 1.12 1.4 0.6 1.52
STD 0.84 0.45 0.65 0.61 0.5 0.71 1.08 0.65 1.23
HIGH AVE 1.5 1.1 1.86 3.2 1.5 3.5 3.8 1.7 4.16
STD 0.94 0.65 0.69 0.75 0.5 0.85 0.45 0.45 0.49
θ s 5 θ sm 1 θ st . AVE, Average deflection; STD, standard deviation.

9.3.3 Experimental results

In the experiments, the flexible robot was controlled to drill through the gelatin with LOW,
MEDIUM, and HIGH speed for five times each. The total bending angle of the bendable
joint was set to 0, 80, and 160 degrees, which can meet the drill practice for surgical
requirement. The average deflection of the flexible drill at the distal of the bendable joint is
presented in Table 9.2.

The relation between the deflection of the flexible drill and the bending angle of the
bendable joint is shown in Fig. 9.8.
The experimental results demonstrated that the deflection of the flexible drill gradually
increases when the bending angle rise up from 0 to 160 degrees, and the maximum average
deflection is 4.16 mm when the drill works on high speed state. Meanwhile, the deviation in
x-axis is larger than that in the y-axis.