Design and kinematics characterization of a laser-profiled continuum manipulator for the guidance of bronchoscopic instruments

Bronchoscopic intervention, as a minimally invasive method for the diagnosis and treatment of lung diseases, has attracted more and more attention in recent years. However, existing endobronchial instruments lack the steerability accessing the peripheral airways with difficult bifurcations. This paper presents a novel wire-driven dexterous manipulator for the guidance of such instruments. Precision laser profiling is used to cut a stainless steel tube into multiple interlocked segments with revolute joints. The outer diameter of the manipulator is 2.20 mm which is small enough to be inserted into the working channels of most commercial bronchoscopes and distal airways, while keeping a large inner lumen with a diameter of 1.44 mm for passing various bronchoscopic instruments. The small bending radius provides enough flexibility to navigate inside the complex bronchial tree. Two kinematic models are proposed to predict the manipulator configuration from the translation of actuation wires. The former model is geometrically derived with the assumption of constant curvature bending and the latter one is statistically driven by capturing the motion trajectories of manipulator joints. A prototype of our low-cost add-on instrument guidance robot for bronchoscopic intervention is presented which can be easily integrated into current clinical routine.