Experimental Assessment of Positioning Precision During Free-Hand and Robot-Assisted Tool Manipulation in Transoral Microsurgery Model

Transoral laser microsurgery (TLM) is a vocal cord cancer treatment where surgical tools reach the targeted region through the mouth. A robot-assisted system could aid in such operation yet there is limited understanding of the precision that is reachable at the level of the vocal folds. Therefore, this paper analyzed the baseline of human tool positioning capability during simulated TLM. In a simulated TLM environment, 31 participants navigated a probe to reach the target region of variable diameter ranging from 2.0 mm to 0.1 mm. The total execution time and the number of incorrect contacts were recorded. To assess the positioning potential under robotic assistance, 5 volunteers conducted the same tasks with the help of a co-manipulation robot. The minimum target diameter humans can precisely achieve at the vocal fold is 1.5 mm (time: mean ${=} \,\, 13$ .92 s, SD ${=} \,\, 12$ .30 s, incorrect contact: mean ${=} \,\, 2.71$ , SD ${=} \,\, 4.53$ ) while with the co-manipulation system, the precision can be improved to 0.2 mm (time: mean ${=} \,\, 21$ .20 s, SD ${=} \,\, 12$ .31 s, incorrect contact: mean ${=} \,\, 3.84$ , SD ${=} \,\, 2.95$ ). The experiments successfully established a baseline for free-hand precision reachable at the vocal fold and potential improvement through robot assistance.