Concentric Tube Robots
For this project, we derived the equations of motion necessary to control both the forward and inverse kinematics of the concentric tube robots. Despite a compressed two-week timeline, our team developed a kinematic model capable of predicting end-effector position with less than one millimeter of error in simulation across all directions.
Experimental results showed larger discrepancies, with errors reaching a few millimeters in certain directions. This deviation is likely due to the use of low-cost nylon tubing that was manually heat-formed to achieve the desired curvature. Variations in material properties, non-uniform curvature, and elastic deformation introduce modeling inaccuracies that are not captured in the ideal kinematic formulation.
A more standardized approach would involve using pre-manufactured nitinol tubing, which offers superior shape consistency and repeatability. However, nitinol is significantly more expensive and fragile, making it unnecessary for early-stage experimentation where low-cost prototyping and rapid iteration are prioritized.
Concentric Tube Robots (CTRs) are miniature, highly dexterous robotic systems constructed from multiple pre-curved, telescoping tubes. By rotating and translating these tubes relative to one another, the robot can steer along complex, curved paths that are difficult or impossible for traditional rigid instruments to follow.
Because of their small diameter and flexible motion, CTRs are particularly well-suited for navigating confined anatomical spaces such as narrow blood vessels, airways, and deep surgical corridors. This capability enables minimally invasive procedures with improved precision, reduced tissue trauma, and access to previously unreachable regions.
As a result, concentric tube robots are increasingly being explored for applications in endovascular surgery, neurosurgery, and other procedures requiring accurate manipulation within delicate and intricate anatomical structures.
The robot we used is an open sourced CTR made in the same lab we conduced our class in: the COMET lab at WPI led by Professor Fichera. Link to the robot and all educational material on how to assemble and build you own CTR can be found here: