Trans-bronchoscopic diagnosis and intervention in the lung is a new frontier for steerable needles, where they have the potential to enable minimally invasive, accurate access to small nodules that cannot be reliably targeted today. However, the curved, flexible bronchoscope requires a much longer needle than prior systems have considered, with complex interactions between the needle and bronchoscope port, introducing new challenges in steerable needle control. Friction between the port and needle causes torsional windup along the bronchoscope. This effect cannot be directly measured at the tip using the latest small-diameter needles which feature 5 degrees of freedom magnetic tracking coils. To make use of this sensor and compensate for torsional deformation along the needle, we propose a new torsional deadband-aware Extended Kalman Filter to estimate the full needle tip pose including the axial angle, which defines its steering direction. We use the Kalman Filter estimates with an established sliding mode controller to steer along desired trajectories in lung tissue. We demonstrate that this simple torsional deadband model is sufficient to account for the complex interactions between the needle and endoscope channel for control purposes, enabling targeting to within 1.36 mm in phantom tissue and 2.14 mm in ex-vivo porcine lung.


Steerable Needle Trajectory Following in the Lung: Torsional Deadband Compensation and Full Pose Estimation With 5dof Feedback for Needles Passing Through Flexible Endoscopes

Division / Sponsors: 
Dynamic Systems & Control (DSCD)

Paper Proceedings: https://asmedigitalcollection.asme.org/DSCC/DSCC2020/volume/84270

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