Elliptical torus-based Six-axis FBG Force Sensor with In-situ Calibration for Condition Monitoring of Orthopedic Surgical Robot*

摘要

Six-axis force/moment (6-A F/M) sensors make surgical robots effectively sense intraoperative force feedback and drilling status information, reducing the operating challenges and psychological burden of doctors, which also improves the quality and safety of surgery. However, it is difficult for current commercial electrical 6-A F/M sensors to adapt the electromagnetic environment in the operating room, and status changes after installation can also reduce accuracy. At the same time, there is a strong vibration coupling of low-frequency force information, leading to low identification accuracy and slow response speed in the drilling and milling status. Aiming at these problems, an elliptical torus-based 6-A fiber optic F/M sensor and its in-situ calibration method for orthopedic surgical robot force sensing are proposed. Furthermore, combined with the multichannel one-dimensional convolutional gated recurrent unit (M1-DCGRU), a fast and accurate identification of seven drilling stages was realized. The final force sensing error is less than 7.1%, and the drilling state identification accuracy is at least 93.9%. The designed sensor has higher accuracy, is compatible with magnetic resonance imaging (MRI), and accurately identifies finer drilling stages without relying on other sensors.