A Miniature 1R1T Precision Manipulator with Remote Center of Motion for Minimally Invasive Surgery

In robotic-assisted minimally invasive surgery, the remote center of motion (RCM) achieves precision and safe manipulation of surgical devices through the insertion point into the patient’s body. One of the RCM configurations, one-rotation and one-translation (1R1T) RCM based on a closed-loop design, enables two-degrees-of-freedom transmission from the proximal end of the robotic arm to the distal end. This feature offers important advantages, particularly in enhancing safety by minimizing physical contact risks with patients or other surgical tools owing to the simplified layout near the surgical field. However, conventional 1R1T RCM robots typically employ complex structures with numerous joints consisting of pin-and-hole mating mechanisms. This complexity can increase the overall size of the robot and compromise motion precision. This study presents a miniature 1R1T precision manipulator with RCM, ORIGANOID (dimensions: W60 x D120 x H30 mm, weight: 12.6 g). The robotic arm features flexure hinges, eliminates clearance issues, and can be fabricated using an origami-inspired robotic approach. Furthermore, using a novel backlash-free coupling method, the robotic arm could be easily attached and detached from the drive units. A prototype was fabricated and experimentally validated. The results demonstrated that high-resolution motion could be achieved within 10 μm. Furthermore, a demonstration using an eyeball model confirmed the successful implementation of 1R1T RCM.