Mechanical Design and Optimization of a Microsurgical Vitrectomy Robot

This research project focused on the design and optimization of the Stewart parallel robot used for vitrectomy. I designed a small linear actuator for the prismatic joints of the Stewart platform. The entire actuator is 80 mm long, and constains no backlash. The precision of the actuator is key to the success of the surgical robot, since vitrectomy requires high precision. The SolidWorks model is shown below. The width of the entire actuator is less than the diameter of a penny.

In addition to the prismatic actuators, I worked with Ph.D. student Wei Wei to simulate the configuration of the Stewart platform to cover the workspace of the eye. I developed a simulation in MATLAB to compute the optimal joint angles for mounting the legs to the base and moving platform. I also worked on the custom-designed universial joints used in the moving platform. A numerical evaluation of available plain bearings showed how we could improve the tilting range of several bearings on the market, such that they would fulfil the tilting requirements found in the joint angle simulation.

Feasibility Study of Magnetically Actuated Robots

This project looked at the possiblity of controlling a 3 DOF parallel robot from outside the body using magnetic fields. It also looked at the current requirements for the robot under the assumption that these magnetic fields could be generated very close to the robot's revolute acutators. A 3RRS robot was simulated in MATLAB and used the Jacobian to compute the current. It also performed the inverse kinematics necessary for describing the workspace.

This is the 3RRS robot I analyzed for workspace capabilities and current requirements.

The workspace of the 3RRS robot is shown in the blue dots (position) and red arrows (orientation).