Control design and task performance in endoscopic teleoperation

Endoscopic surgery, while offering considerable gains For the patient, has created new difficulties for the surgeon. One problem is the fulcrum effect , which causes the movement of a surgical instrument, as seen on the monito r, to be in the opposite direction to the movement of the surgeon's hand. T he problem has been shown to impede the acquisition of endoscopic skills. T eleoperated robotic arms may circumvent this problem by allowing different control-response relations. Four alternative control designs of a teleopera ted device were compared in a simulated endoscopic task A rigid teleoperate d robotic arm with two degrees of Freedom representing a surgical tool was coupled to a joystick in a position control mode, Feedback was provided thr ough a video display, Participants without prior experience in endoscopy pe rformed a target acquisition task first by pointing the robotic arm at the targets, and later by maneuvering an object. Performance was measured under four different combinations of visual-motor mapping (normal/reversed), and the joystick's orientation (upwards/downwards). Task completion time under normal visual-motor mapping was found to be significantly shorter than und er reversed visual-motor mapping, emphasizing the potential advantage of a teleoperated endoscopic system. The joystick's orientation affected the man euvering of an object under only the reversed visual-motor mapping, implyin g that the positioning of a surgical tool and the manipulation of tissues o r objects with the tool may be differentially affected by the control desig n.