Systematic Characterization of Drilling Parameters in Concentric Tube Steerable Drilling Robots: A Comparative Study
Daniyal Maroufi, Yash Kulkarni, Vibhu Kanna Rajesh Kanna, Jordan P. Amadio, Mohsen Khadem, Justin E. Bird, Jeff Siewerdsen, Farshid Alambeigi
AI summary
Problem
Conventional rigid spinal robots cannot navigate curved paths to target dense bone, and existing flexible Concentric Tube Steerable Drilling Robots lack quantitative guidelines for optimal feed rate and rotational speed.
Approach
The authors developed and compared custom high-speed and low-speed CT-SDR systems, systematically testing varying feed rates and rotational speeds across synthetic bone phantoms to measure torque, hole diameter, and trajectory curvature.
Key results
- High-speed drills successfully penetrate dense synthetic bone where low-speed drills stall
- Slower feed rates reduce hole enlargement and improve trajectory curvature accuracy
- Higher rotational speeds yield smoother motor current profiles and more consistent cutting torque
- Quantitative performance trade-offs established for CT-SDR design and operational control
Why it matters
Provides quantitative guidelines for designing and operating flexible steerable drilling robots to improve spinal fixation safety and efficacy in patients with varying bone densities.
Abstract
To establish a foundational understanding for creating J-shaped trajectories with Concentric Tube Steerable Drilling Robots (CT-SDRs), this paper presents a systematic characterization of two operational factors: drill feed rate and rotational speed. We developed and compared a custom High- Speed Drill (HSD) and a Low-Speed Drill (LSD) to analyze how these parameters affect performance in flexible robotic drills versus conventional systems utilizing rigid instruments. By integrating the CT-SDRs with a seven degree-of-freedom robotic manipulator, we conducted experiments in synthetic bone phantoms of varying densities, assessing metrics such as motor current, hole diameter, radius of curvature, and drilling time. The results reveal critical performance trade-offs, demonstrating that high-speed drilling in CT-SDRs is essential for successfully penetrating dense bone. Further, we found that while slower feed rates improve trajectory accuracy and reduce hole enlargement, they significantly increase procedural time. These findings offer a quantitative guideline for design choices, component selection, and operational control of CT- SDRs tailored to patient-specific bone quality.