Calibration method for 3-dimensional tip position tracking sensor

We described a calibration method for 3-dimensional tip position tracking sensor. This sensor consists of three optical fibers containing multiple fiber Bragg gratings. Each fiber Bragg grating measures a strain at their position as the sensor bends, then curvature and bending direction at the position is calculated. Finally, the position of the sensor tip was calculated from the information. Because the location of each fiber Bragg grating is very important to calculate tip position exactly, compensation to minimize the error caused by fabrication process is inevitable. The sensor was deflected in eight directions, and the position of the sensor tip was measured exactly by the camera with telecentric lens. Next, the deflected distance and tilted angle of the tip position from the original position were calculated by shape sensor. The two data were compared and compensated using simple linear regression analysis. The final error of calibrated single bending system was less than 1%.