Page 173 - Flexible Robotics in Medicine
P. 173

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.
   168   169   170   171   172   173   174   175   176   177   178