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Handheld flexible robot with concentric tubes aiming for intraocular procedures 159
6.3.5 Casing
The casing comprises three distinct pieces: front panel, top panel, and side panel (Fig. 6.7).
Each piece is duplicated to cover the opposite sides (front and back, top and bottom, left
and right). All components are mounted to either the top and bottom panels or the front and
back panels. This facilitates easy troubleshooting of the device, as either side (or both)
panels can be removed without affecting the operation of the device. The control buttons
allow the device to be grasped with an overhand grip, which supplies a secure grip on the
device while maintaining a stable RCM. As the motors do not have inbuilt encoders, limit
switches were installed as an elementary solution to position tracking (Figs. 6.8 and 6.9).
6.4 Kinematics and motion control interface
Fig. 6.10 shows a model of the CTR, with the origin of the reference frame fixed at the
proximal end of tube 1. Given the radius of curvature, R, and the angle of curvature, θ,we
0 1
x
can relate the position of the tip of tube 2, @ A to the reference frame.
y
z
t 5 Rφ (6.1)
Figure 6.7
Device casing.