Evaluating control modes for constrained robotic surgery

Minimally invasive surgery (MIS) constrains instrument motions to 4 DOF by precluding lateral motion at the incision. Robotic MIS systems can interpose arbitrary mappings between the surgeon´s motions at the master controller and the motions of instrument tips within the patient´s body. Our goal was to find the interface that was easiest to learn. We investigated the effects of different coordinate frame mappings (screen-mapped versus instrument-mapped) and master dexterities (6 DOF versus 4 DOF) by means of performance measures on simple surgical tasks. All four mode-dexterity combinations had approximately the same time-to-completion. The combination of instrument-based mapping and 4 DOF master had lower error rate and lower subjective workload. This mode most clearly reproduces the task constraints within the patient´s body