A Palm-Sized Anthropomorphic Parallel-Serial Robot for Ophthalmic Surgery

Deriving from the posture of instrument holding of human surgeons, this paper develops a hybrid parallel-serial robot for ophthalmic surgeries. Each serial branch makes use of a compact five-bar mechanism for distal actuation with increased rigidity in the direction of gravity. The designed robot manipulator has a variable remote center of motion (RCM), such that small eye ball motion can be compensated for without translating the entire platform. As such, the alignment can be less time-consuming, as opposed to those fixed RCM designs. To streamline the multi-tool surgery, a passive tool exchange mechanism is proposed. The mechanism utilizes the bi-stable positions of push-push button to load and unload the surgical instrument, whereas the permanent magnets and kinematic coupling on the manipulator serves to constrain the tool with adequate fixation force. The physical prototype confirms the sufficient range of motion for retinal operations and the tool exchange capability.