Synthesis and methodology for optimal design of a parallel remote center of motion mechanism: Application to robotic eye surgery

This work reports on the synthesis of a parallel Remote Center of Motion (RCM) mechanism, and an optimized design for the use-case of robot-assisted vitreoretinal surgery. A 2-DoF planar RCM mechanism is proposed and synthesised as part of a 4-DoF RCM mechanism. The proposed design substantially reduces the occupied volume at the end-effector. This solves a major problem present in related state-of-the-art, which poses limitations on sterile end-effector design and surgical instrument compatibility. Subsequently, an optimal design algorithm is proposed and implemented for the given use-case. The workspace is determined within mechanism constraints, after which performance parameters such as workspace coverage, potential energy, manipulability, reflected stiffness are determined for specific areas of interest within a desired workspace. Subsequently, these parameters are combined in a score function identifying an optimal kinematic design. When compared with the closely-related prior art, the resulting design shows improvements in relevant workspace coverage, reduced gravity compensation effort, and more isotropic manipulability. Overall reflected stiffness is reduced and should be taken into account in future design phases. Future work includes the integration of the kinematic design into a detailed conceptual design and a first prototype development. (c) 2020 Elsevier Ltd. All rights reserved.