| Abstract: | Large instruments are not suitable for laparoscopic surgery because they cannot pass through trocars, which are typically less than 12 mm in diameter; however, operating on large internal organs with a slender instrument is often difficult. To overcome this limitation, we have proposed an 'assemblable instrument', whose parts are inserted through trocars and assembled inside the abdominal cavity to form a large instrument. We have previously reported the development of assemblable hands that require two trocars for assembly. In this paper, we propose a simple three-fingered hand whose function is limited to retracting or grasping, but whose assembly requires a single trocar. We develop two types of finger units: one for a retracting hand and the other for a grasping hand. The two finger units can be connected to a single main unit of the hand. We conduct in vivo experiments. The retracting hand can retract several large internal organs and lift up the stomach with its three fingers from the bottom. The grasping hand can grasp the spleen stably with its two fingers from the bottom. |
