Optimal Design and Dynamic Analysis of a Hybrid Manipulator for Intra-ocular Surgeries

This study aims to develop a new robot for vitreo-retinal eye surgery applications, referred to as PERSIS (Precise Robotic System for Intraocular Surgeries). It consists of a linear mechanism coupled to a parallelogram mechanism that has a remote center of motion (RCM) point. The RCM point is employed for manipulating the surgical instrument about this fixed point, where it acts as a pivoting point. Moreover, as the insertion point of the robot is fixed, a gantry mechanism is designed to add three translational Degrees of Freedom (DOF) to the RCM mechanism. According to the above description, the optimal design of the proposed mechanism to achieve superior performance in eye surgery is critical. Therefore, the optimal design of 6DOF mechanism based on the constrained nonlinear optimization is performed according to the requirements of vitreo-retinal surgery and dimensions relevant to the anthropometry of the human head. Moreover, in the eye surgeon robot, due to the accuracy required in routing the surgical instrument, having a relatively accurate description of the robot dynamic equations is necessary. In this paper, a closed-form of equations of motion for PERSIS is generated. Instead of computing the coupled dynamics directly, dynamic equations of the parallelogram and the gantry mechanism are calculated separately and then, dynamic equations of the proposed hybrid mechanism are calculated.