intraOcular RoBotic Interventional System (iORBIS): Mechanical design for distally-actuated instrument insertion and automatic tool change

Parallelogram-based remote center-of-motion (RCM) mechanisms have been intensively deployed in intraocular surgical robots. However, the actuation of instrument linear movement in conventional parallelogram-based RCM mechanisms is mostly done by a linear actuator installed near the end-effector. This design inevitably increases the volume and mass on the patient side of the robot. In this work, we present a novel parallelogram-based RCM mechanism that allows distally-actuated instrument insertion and retraction. Compared to the existing work, the proposed mechanism decouples the translational motion from other rotational degrees of freedom with a simple design. This feature may further enhance the safety of delicate procedures like sub-retinal injection. Based on the kinematic analysis, a method is developed for assembly error estimation and correction. Moreover, an automatic instrument changer is integrated with the robotic manipulator. Experiments are conducted on a prototypical system to validate the feasibility of the proposed design. The RCM precision is shown as better than 0.5 mm. The time required for switching surgical instruments is demonstrated as less than 10 s. ? 2021 Elsevier Ltd