Design, prototype and control of a 3R1T robot with RCM for eye surgery

Forward and inverse kinematic models were developed, alongside singularity analysis and dimensional synthesis, confirming the presence of an RCM and a singularity-free workspace during normal operation.<br><br>To address the stringent geometric constraints inherent to parallel RCM mechanisms, an error model and a novel metrology-assisted fabrication and assembly methodology were developed and implemented. This approach ensured the RCM geometric constraints were maintained within ±0.052 mm.

A physical prototype comprising 62 bespoke components and 341 standard parts was manufactured and assembled. A new dynamic motor-sizing methodology was also introduced to account for varying load conditions across the robot’s operational cycle.<br><br>Hardware and control integration was achieved using a MicroMACS6 master controller and EPOS4 motor controllers communicating via CAN, with a preliminary control strategy implemented in Cyclic Synchronous Position mode.

Experimental evaluation demonstrated ±40° pitch and yaw rotation, a 50 mm translational stroke, and tool orientation repeatability of ±22.86 μm. This performance is superior or comparable to reported results from existing surgical robotic systems and meets the workspace and precision requirements for cataract surgery.<br><br>The results demonstrate that the proposed 3R1T parallel robot is a viable and promising platform for robotic eye surgery.

The thesis concludes by identifying current limitations and presenting a structured roadmap for future development towards clinical deployment.<br><br><i>Thesis is embargoed until 31 July 2031.</i>