Controlling the traditional rigid endoscopic instrumentation motion

Abstract

The paper deals with the development of a version of Navi-Robot suitable for controlling the endoscope's and instrumentation's position during a laparoscopic surgery. The basic structure is the same of Navi-Robot, a three arms measuring device where each of the arms bears a 6 DOF self balanced kinematic chain. The central arm is able to pass from passive to active mode upon command, all the arms being lockable in any position. Adding a motor to control rotation of the sixth joint of the lateral arms and another 4 DOF Robot to control the second degree of inclination of the surgical tool with respect to the patient's body surface, as well as penetration, rotation and actuation of the instrument (the first degree of inclination being controlled by the sixth DOF of the lateral arms of the Navi Robot). Another key element is the way rotation and actuation are controlled. To this purpose two spur gears are used, the first of which is to be fixed to the surgical tool, while the second, fixed to the first gear but free to rotate with respect to it, actuates the handle of the surgical tool using a four bar link and a couple of bevel gears. This pair of spur gears are positioned on a body that allows transmitting the motion through pinions coupled to other bevel gears and universal joints that allow receiving the motion from the non sterile part of the instrument. Finally two different schemes were studied to control the motion of the instrument, and are described in this paper together with their relative advantages and disadvantages. © Springer Science+Business Media B.V. 2009.