Real-Time Temperature-Compensated and Filtered Force Sensor Based on FBG String for Surgical Robot

The lack of force information in surgical robots introduces new risks, such as injuries caused by too much force. This article presents a novel real-time temperature-compensated force sensor for surgical robot, which can provide real-time multidimensional force information without changing the structure of the surgical tool, but only installing one sensing fiber with four fiber Bragg gratings (FBGs). The finite element simulation shows that each FBG is subjected to different temperature changes under the influence of heat source. In order to achieve more accurate temperature compensation (TC), the sensitivity of reflectivity of FBG to strain and temperature is analyzed by theory and experiment, and TC is also realized with the dual parameter of reflectivity and wavelength shift. In addition, a zero-phase filter based on single-sided extension of fitting point is further designed to process the force signals, which eliminates the time delay introduced by traditional filters while filtering out interference signals. Finally, the effectiveness of this study is demonstrated by comparing the results with commercial force sensor.