This paper presents an intraoperatively iterative Hough transform (IHT) based in-plane hybrid control of extracorporeal ultrasound (US) guided magnetic catheterization for arterial intervention. One uniqueness lies in that both control and tracking of the arterial robotic ultrasound end-effector have been implemented to improve performance. Firstly, the magnetic catheter model and hybrid visual/force servoing control scheme of the extracorporeal ultrasound-integrated tracking arm (EUTA) are derived based on the interaction Jacobian matrix and impedance modeling. Meanwhile, we implement a tracking method of in-plane ultrasound catheter’s tip and detection of vascular boundaries utilizing intensity-level iterative Hough-transform with Iterative End-Ponit Fitting (IEPF). The effectiveness of the proposed control and tracking method has been verified by conducting in vitro experimental studies for catheter steering of a soft tissue-imitating phantom. Results show that an average steering error of 0.56 mm and signal-to-noise-ratio (SNR) of 12.2 are obtained for the ultrasound imaging at high synchronization along with a low target lost rate (15.8%) and constant-force tracking (2.50±1.02 N).

Autonomous magnetic catheterization has become a promising technology for next-generation minimally invasive cardiovascular surgery. In this paper, a novel homocentric variable-stiffness magnetic robotic catheter (HVS-MRC) is presented. This device is controlled by a multi-arm robot-assisted catheterization system for use in radiation-free coronary ultrasound intervention. The uniqueness of the HVS-MRC is the generation of variable stiffness through the telescopic motion of three homocentric components with embedded internal magnets. These components can be used to achieve multiple curvatures and large deflections ($>$120 degrees) under a magnetic wrench provided by an external mobile magnet module (EMMM) to adapt to the complex coronary environment. The variable-stiffness kinematics modeling, multivessel selection strategy, and preoperative surgical planning of the proposed magnetic robotic catheter are established. Meanwhile, an extracorporeal mobile ultrasound module (EMUM) is adopted to intraoperatively localize the catheter's in-plane motion with a dominant visual/force feedback controller. A hierarchical relative control scheme is proposed based on the relative Jacobian method to synchronize the motions of the multi-arm robot-assisted catheterization system. The overall performance is evaluated with anin vitrohuman-sized coronary arterial phantom with challenging anatomical variabilities. The results reveal that the HVS-MRC exhibits a high-accuracy intervention performance (average error of 1.52$ \pm$0.35 mm) with smoother steering compared with conventional catheters. High synchronization with a low ultrasound target loss rate (15.8%) and constant-force tracing (2.50$\pm$1.02 N) of the multi-arm robot-assisted catheterization system demonstrate promising application potential in radiation-free autonomous ultrasonographic coronary intervention operations.