An Occlusion-Free Intraoperative Active Navigation System for Orthopedic Surgery

Intraoperative optical tracking system (OTS) suffers from the visual occlusion problem when an obstacle blocks the visual cone (VC) of the OTS. In this article, angle and distance margins are proposed to quantify the degree of danger of an obstacle based on its spatial relationship to the VCs of the OTS. Based on this mathematical modeling, an active navigation system (ANS) is proposed, where the navigation robot is used to adjust the pose of the OTS before occlusion occurs. Circular and translational trajectories are proposed as basic adjusting trajectories for the OTS. A dual-step optimization is then established to find the optimal observation pose of the OTS and plan an occlusion-free adjusting trajectory for the navigation robot. Finally, simulations and experiments are conducted to validate the effectiveness of the proposed method. The results demonstrate that the proposed method effectively keeps the VCs of the OTS away from the moving path of the obstacle, and thus maintaining consistent navigation. This active navigation method is promising for the safe operations of surgical systems employing optical navigation.