Evaluation of a pneumatic surgical robot with dynamic force feedback.

Robot-assisted surgery is limited by the lack of haptic feedback and increased operating times. Force scaling adjusts feedback transmitted to the operator through the use of scaling factors. Herein, we investigate how force scaling affects forces exerted in robotic surgery during simple and complex tasks, using a pneumatic surgical robot, IBIS VI. Secondary objectives were to test the effects of force scaling on operating time, depth of needle insertion and user satisfaction. Two novice males performed simple (modified block transfer) and complex (needle insertion) tasks under four scaling factors: 0.0, 0.5, 1.0 and 2.0. Single-blind experiments were repeated five times, with alternating scaling factors in random order. Increasing the scaling factor from 0.0 to 2.0 reduces forces in block transfer (p = 0.04). All feedback conditions reduce forces in needle insertion compared to baseline (0.5: p < 0.001, 1.0: p = 0.001, 2.0: p = 0.001). Time to complete block transfer is shorter for scaling factor 0.5 (p = 0.02), but not for 1.0 (p = 0.05) or 2.0 (p = 0.48), compared to baseline. Depth of needle insertion decreases consistently with incremental scaling factors (p < 0.001). Further reductions are observed upon augmenting feedback (0.5-2.0: p = 0.02). User satisfaction in block transfer is highest for intermediate scaling factors (0.0-1.0: p = 0.01), but no change is observed in needle insertion (p = 0.99). Increments in scaling factor reduce forces exerted, particularly in tasks requiring precision. Depth of needle insertion follows a similar pattern, but operating time and user satisfaction are improved by intermediate scaling factors. In summary, dynamic adjustment of force feedback can improve operative outcomes and advance surgical automation.