Design of 4-DOF parallelogram-based RCM mechanisms with a translational DOF implemented distal from the End-Effector

Abstract

Numerous passive and active tool holders for minimally invasive surgery consisting of a remote center of motion (RCM) mechanism with four degrees of freedom (DOFs) have been developed. These are mostly serial mechanisms composed of three 1-DOF RCM mechanisms and a 1-DOF translation stage. In the vast majority, the translation stage is implemented proximal to the end-effector resulting into a heavy and voluminous end-effector. To provide easier access to the surgical site and facilitate use of multiple instruments and holders, this work elaborates on the design of 4-DOF parallelogram-based RCM mechanisms featuring a 1-DOF translation mechanism implemented distal from the end-effector. Kinematical design rules to develop such mechanisms are derived. Guidelines on how to apply these design rules and three interesting embodiments are given.