F-VIS: Efficient Robotic Tactile Sensing via Fiber Bragg Grating-Based Force and Vision Fusion

This article introduces F-VIS, a novel visual–tactile sensor that integrates direct force measurement based on fiber Bragg grating (FBG) with vision-based tactile sensing. F-VIS achieves multimodal tactile perception in real time by combining high-precision force and visual data, without relying on marker layers or data-driven force estimation. The sensor uses three spiral structures for 3-D force measurement (Fx, Fy, and Fz) and a designed contact body for tactile image acquisition and depth reconstruction. Static calibration experiments show that F-VIS has root-mean-square error (RMSE) values of 0.01, 0.018, and 0.022 N for$F_{x}$,$F_{y}$, and$F_{z}$within the$\pm$5 and [0, 10] N ranges. It also achieves an average RMSE of 0.12 mm in depth reconstruction. Fusion experiments show the sensor achieves RMSE of 2.5 pixels and 0.12 N for contact location and force, respectively. With high sensitivity (up to 24.95 pm/N) and a 100-Hz operating frequency, F-VIS enables rapid, precise force detection. Temperature compensation keeps FBG drift under 7 pm (25$^\circ$–50$^\circ$); after 500 cycles, transmittance rises 0.36%. F-VIS excels in hardness detection, object classification, and delicate manipulation, detecting 0.16 N forces and capturing slip forces. It outperforms existing sensors with superior precision, responsiveness, and versatility.