A local hybrid actuator for robotic surgery instruments

A major problem in the design of miniature scale motorised endoscopic instruments is the actuation mechanism at the instrument’s tip, especially when a high level of functionality and multi degrees of freedom (DOF) are concerned. In the present study, a new design for hybrid local-actuation of endoscopic instruments is proposed which includes a micro DC motor and a piezoelectric (PZT) actuator. A compact serial configuration was considered for the actuators. The DC motor provides the long movement course required for opening-closing function of the gripper while the PZT guaranteed the high gripping force needed for holding the needle. The efficacy of the design was evaluated in a simulation study using FEM, and it was shown that the needle holder is capable of applying a sufficiently high gripping force, up to 22 N. The feasibility of the design was further approved in experimental examination of a 4× scaled prototype of the instrument.