Online viewpoint optimization method for high-accuracy intraoperative optical measurement in orthopedic surgeries: An active navigation approach

In robotic orthopedic surgeries, the optical tracking system (OTS) is an essential technology to obtain the high-accuracy relative pose between the patient and surgical instrument via positioning tools. Typically, the OTS viewpoint is manually placed by surgeons and remains stationary afterwards. However, due to the limited measurement volume (MV), adjustments made to either the patient’s body or surgical instruments may move positioning tools beyond the MV, potentially leading to measurement failure. To tackle this issue, this paper proposes an online viewpoint optimization method to adjust the OTS viewpoint actively. Considering the safety of the operation, the adjustment to the OTS is only implemented when necessary. In the presence of multiple moving positioning tools, the OTS’s real-time adjusting trajectory is optimized to ensure that the OTS consistently tracks all positioning tools, guaranteeing high-accuracy intraoperative navigation consistency. Tests and experimental results validate the OTS’s high dynamic accuracy. For all the experimental results, the mean Euclidean and angular distance errors are below 0.48 mm and 0.30˚ using the proposed method. The maximum Euclidean and angular distance errors are measured as 1.06 mm and 0.84˚. These experimental results demonstrate that the OTS can consistently acquire high-accuracy measurement data from all positioning tools when confronted with moving tools. This active navigation approach promises to maintain high-accuracy intraoperative navigation for the safe operation of surgical systems.