A tele-operated robotic catheterization system can significantly alleviate the surgeons from radiation exposure and fatigue resulted from long standing time with protective suits. Proximal force/torque signals imply the critical information about the contact forces between the catheter and its surrounding structures. This paper presents a compact, cost-effective force and torque sensing device suitable for catheterization procedures to measure the proximal force/torque signals of the input catheter. The device consists of a rotatable and linear retractable mechanism, a laser mouse sensor, and a coil spring. As the stretched, compressed, and twisted values vary due to the sliding joint, the force and torque signals can be computed based on the Hooke’s law. The proposed sensing device has many advantages such as cost-effective, easily miniaturized and customized, and can be extended to the MRI compatible sensors. The experimental results with step response and time-varying loads by comparing to an ATI Nano17 force/torque sensor show that the Root Mean Squared Error (RMSE) for force and torque measurement are 0.042 N and 0.228 mNm respectively.
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J. Guo; M. Li; P. Ho & H. Ren Design and Performance Evaluation of a Force/Torque Sensor for Tele-operated Catheterization Procedures IEEE Sensors Journal, 2016, PP, 1-8
Image guidance during minimally invasive cardiovascular interventions is primarily achieved based on X-ray fluoroscopy, which has several limitations including limited 3D imaging, significant doses of radiation to operators, and lack of contact force measurement between the cardiovascular anatomy and interventional tools. Ultrasound imaging may complement or possibly replace 2D fluoroscopy for intravascular interventions due to its portability, safety, and the ability of providing depth information. However, it is a challenging work to perfectly visualize catheters and guidewires in the ultrasound images. In this paper, we developed a novel method to locate the position and orientation of the catheter tip in 2D ultrasound images in real time by detecting and tracking a passive marker attached to the catheter tip. Moreover, the contact force can also be measured due to the length variation of the marker in real time. An active geometrical structure model based method was proposed to detect the initial position of the marker, and a KLT (Kanade-Lucas-Tomasi) based algorithm was developed to track the position, orientation, and the length of the marker. The ex vivo experimental results indicate that the proposed method is able to automatically locate the catheter tip in the ultrasound images and sense the contact force, so as to facilitate the operators’ work during intravascular interventions.
Research Fellow: Jin Guo
Project Investigator: Hongliang Ren