2.3. Endoscope Robot Module

The endoscope driving actuator unit is a housing that holds the endoscope grip. A flexible endoscope can be easily set into or removed from this unit by closing or opening the door. The grip of the endoscope has two coaxial angle dials actuating the vertical and horizontal bending. The dials are driven by the two coaxial wheels with fitted couplings (Figure 3(a)). The backlash between the knobs and couplings and between the couplings and actuator unit is not large because the couplings were specially designed so that they fit the shape of the knobs. Each coaxial wheel is driven by timing belts. To actuate the twisting motion of the endoscope tip, the entire endoscope driving actuator unit rotates together with the grip part of the endoscope around the endoscope's shaft, as shown by the arc arrow in Figure 3(b). This motion is transmitted to the endoscope tip because the flexible part of the conventional endoscope is made of a torque-transmissive material. The flexible part of the endoscope is held by a push–pull arm to push or pull the endoscope into or out of the patient's mouth or anus; this motion is similar to a manually operated endoscope. The push–pull arm is coupled with the flexible part of the endoscope by an inner pipe attached to the flexible part of the endoscope and an outer pipe fixed to the push–pull arm (Figure 3(b)). The inner pipe can freely rotate inside the outer pipe; therefore, the coupling transmits the forward–backward motion without interfering with the twisting motion of the endoscope. The stroke range of the forward–backward motion is approximately 15 cm, which is sufficient to move around a lesion but not long enough for insertion from the mouth or anus. Therefore, the endoscope is inserted manually (i.e., without robotic actuation) from the mouth or anus to the lesion, as in conventional endoscopy. When the end of the endoscope is near the lesion, the head of the endoscope is affixed in the robot; after this point, the operator can control all motion from the console. The endoscope driving actuator unit contains two actuators coupled to two push valve buttons to actuate insufflation and suction (Figures 3(c) and 3(d)). Half-push and full-push of the insufflation button control the insufflation and lens washing functions, respectively.

Inside the actuator unit driving the endoscope: (a) the driving mechanism with two dials; (b) twisting motion of the entire endoscope; (c, d) air/suction button actuation mechanism.