Fig. 3:

Robot without outer housing. There are four tube modules, an example of which is shown in the magnified view. Two identical modules are lined up along the axis of their lead screws, which makes a half. The half is mirrored and held together along the axis of the endoscope/trocar. The back modules control the inner tube translation and rotation, while the front modules control the outer tube. The threaded gear moves the lead screw to translate the tube, while the keyed gear will translate and rotate the tube. Moving the threaded gear and keyed gear simultaneously commands a pure rotation. On the bottom right of this image can be seen the workspace of the concentric tube manipulators as well as the field of view of the endoscope.