Method for Enhancing Stability of Tension in Cable-Driven Minimally Invasive Surgical Instruments

This study proposes a method aimed at enhancing the stability of tension in cable-driven minimally invasive surgical instruments. Despite the widespread use of cable-driven instruments due to their lightweight and flexibility, those with hinge joints encounter a significant problem of cable loosening during transmission. This is attributed to the non-circular geometric characteristics of hinge joints, leading to a loss of cable tension during transmission and subsequently compromising the precision at the instrument's end. To tackle this issue, a design solution involving a cam is proposed in this study, aiming to provide a more suitable cable length for hinge joints to reduce cable tension loss. Through a series of analytical procedures and experiments, the method optimizes the mechanical design to mitigate tension fluctuations during surgical procedures. Experimental results demonstrate that adopting the design solution with a cam can improve the stability of cable tension in hinge joints by 71% within a motor rotation angle of 30 degrees. This method offers valuable insights into the development of more reliable surgical instruments for delicate procedures.