Orientation estimation of a continuum manipulator in a phantom lung

Abstract

Tendon-driven continuum manipulators are widely used in minimally invasive surgeries, yet autonomous control has proven difficult given the uncertainty in modeling the robot's interaction with the anatomy. In this paper, we test the hypothesis that the anatomy's effect on the robotic manipulator can be approximated as a rotation of the model-based Jacobian. Two methods are described that estimate the orientation using a magnetic position sensor at the robot's distal tip, enabling task-space control in unknown, constrained environments. One method, R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α</sup> , determines the orientation of the robot's model using the measured orientation of the distal tip. In the second approach, R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Δx</sup> , an unscented Kalman filter transforms the tip's measured change in position into an orientation estimate. These methods are validated on the manipulator in free space at three pre-rotated positions (α = 0°, -45°, -90°) and compared to model-based control and model-less control in an autonomous trajectory-following task through an anatomically accurate silicone phantom of a human lung. The results show that by rotating the model-based Jacobian through either of the two methods presented, feedback control successfully navigates the continuum manipulator farther into the lung phantom than static model-based control and model-less control.