Design and evaluation of a variable stiffness manual operating platform for laparoendoscopic single site surgery (LESS).

Abstract

Most of the existing robotic platforms for LESS have workspace and load capacity weaknesses, because of the limitation of one single incision. We have developed a LESS manual operating platform of which the stiffness of the insertion tube is controllable. The system included two dexterous tool manipulators, a stereo-vision module and a variable stiffness insertion tube (VSIT), which was designed using phase-change material (mixed indium, gallium and stannum). Experiments to evaluate the effectiveness of the VSIT were set up. Peg transfer tasks and trajectory tracking tasks were conducted to assess the initial performance of the overall system. The experimental results for stiffness characteristic suggested that the rigidity of the VSIT with a straight-forward pose was considerably increased by about four times in the rigid mode. Peg transfer tasks and trajectory tracking tasks were performed successfully with an average time of 97s and 52s, respectively. The experimental results for stiffness characteristic showed that the manual operating platform had great promise for solving large workspace, high manipulation force and stability problems in LESS. The tool manipulators had the ability to achieve basic operations.