Grasping-Force-Based Passive Safety Method for a Vascular Interventional Surgery Robot System

Abstract

Robot-assisted vascular interventional surgery changes the surgeons’ original operation, which affects their judgment and surgical safety. Therefore, the reliable safety method for robot-assisted surgery is practically valuable. However, the existing active safety methods have two challenges: the difficulty in setting inserting force thresholds suitable for the current vascular environment and the response delay caused by program processing. The paper improved a SEA(series elastic actuator)-based guidewire manipulator with an adjustable grasping force function. A multifunctional finger pulp was designed to measure the guidewire inserting force and perceive the manipulating state between fingers simultaneously. Then, an orthogonal force coupling model based on the mechanical-molecular friction theory was established to demonstrate the friction mechanism of cylindrical surgical instruments grasped by elastic grasping surfaces. Based on the model, a passive safety method was proposed to adjust the grasping force autonomously, which can satisfy the inserting force requirements of the phase delivery task and control the safety threshold suitable for the current environment. The evaluation experimental results demonstrated that the designed robot system could manipulate the guidewire accurately. Then the friction experiments verified the designed orthogonal force coupling model. Finally, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vitro</i> experiments were performed to demonstrated that the designed passive safety method can automatically adjust the grasping force based on the inserting states of the guidewire, reduce the contact force with the vessels, and ensure surgical safety in real-time.