Miniaturized Hyper-Redundant Manipulator Using Multi-Cable for Minimally Invasive Surgery

Minimally invasive surgery (MIS) using robots minimizes patient injury but is challenging due to reduced bending force in smaller-diameter tools. Lowering the bending resistance of actuating cables is critical, particularly when tool diameters are small and cable tension is limited. Traditional methods rely on costly, low-resistance materials. This study proposes a cost-effective design using multiple thin stainless-steel cables and cable slots instead of single cables and conventional cable holes. To optimize the proposed multi-cable design, simulations and polynomial regression were employed to determine the ideal slot dimensions, focusing on reducing bending resistance. Kinematic analysis and experiments confirmed reduced bending resistance in multi-cable designs. A 3 mm prototype showed 25\\% higher bending force and 63\\% increased bending distance under a 1.196 N payload compared to single-cable mechanisms. Circular trajectory experiments demonstrated improved accuracy and reduced velocity variation. A prototype successfully excised a tumor from a BALB\/c mouse, verifying sufficient force for surgical tasks. Future work will address assembly challenges and explore cable arrangement effects on bending force and hysteresis.