A Robot-Assisted Spine Surgery System Based on Intraoperative 2D Fluoroscopy Navigation

In this paper, a robotic system based on intraoperative 2D fluoroscopy navigation in which fluoroscopy images are obtained by C-arm popularized in the clinic, for spine surgery is proposed. The procedure of robot-assisted spine surgery is designed and described. An improved special 6-dof hybrid robot considering both the stiffness and workspace is proposed. And the kinematic model and jacobian matrix of robot are established. To realize fluroscopy images acquisition and avoid interfering with the patient during the process of positioning, human-robot cooperation based on fuzzy variable admittance control considering arm stiffness which would influence the stability of robot, is applied in robotic system. In addition, navigation techniques containing a novel bi-planar design, a robust circular control point detector and closed-loop positioning of tool, based on fluoroscopy images are proposed. In experiments, kinematic model of hybrid robot is test based on laser tracker and the distance error is 0.17 mm which is much smaller than the motion range. The effect of tool weight compensation is measured and the max mean force and torque errors are 0.7477N and 0.0617 N.M. The experimental results could meet requirements in human-robot cooperation. Furthermore, we test the the robotic system proposed in this paper on spine model bone and cadaver with the help of surgeons. The experimental results are validated by 2D image c-arm-based and 3D image CT-based and considered clinically acceptable.