Motion Planning for Concentric Tube Robots

Concentric tube robots are snakelike manipulators that have the potential to enable new minimally invasive surgical procedures by curving around anatomical obstacles to reach difficult-to-reach sites in body cavities. These devices consist of a set of thin, pre-curved, telescoping, concentric tubes which can each be independently rotated and extended relative to one another. Through careful manipulation of the individual tubes, the entire robot can completely change shape and trace incredibly intricate paths. However, their shape-changing properties complicate the motion planning process. Motion planning for concentric tube robots should be computationally efficient and account for obstacle avoidance; efficiency is crucial for motion plans to be computed in the time frames typical of a fast-paced surgical environment, and avoidance of anatomical structures like vessels, nerves, and tissue can prevent patient injury during a procedure. We present a sampling-based motion planner which efficiently computes actuator inputs to guide the tip of the concentric tube robot to a specified goal region while minimizing the estimated probability of colliding with anatomical obstacles like vessels and sensitive tissue. We demonstrate the effectiveness of the planner by computing a motion plan for an anatomy-based neurosurgery procedure involving endonasal access to the pituitary gland. With the help of our motion planner, concentric tube robots have the potential to open a whole new realm of possibilities for laparoscopic procedures, and to change the lives of patients with previously untreatable conditions.