Polymer-Based Optical Waveguide Triaxial Tactile Sensing for 3-Dimensional Curved Shell

To realize dexterous robotic manipulation and enhance the human-machine interaction, nowadays increasing efforts have been made towards multi-dimensional force sensing. However, there are still bottlenecks in integrating these sensors into robots because of the limitation on conformability to complex surfaces and miniaturization. To overcome the above challenges, we proposed a novel polymer-based waveguide tactile sensing method by embedding elastic optical waveguide channels into a 3D curved shell. By surrounding a soft tactel with four channels, the tactel is capable to measure normal and shear forces. We demonstrated that 3-axis force sensing is achieved on a shell structure with thickness of 2.1 mm. The average gauge factor in detecting the normal force from 0 to 1.1 N is -0.2207 N-1, while the value is -0.1976 N-1 in the shear force sensing from -1 to 1 N. A force resolution of 0.1 mN has been achieved, and the proposed sensor has an average hysteresis of 22.23%. It performs well in dynamic force testing of 10 Hz and reaches average angle error 9.7357 degrees and average amplitude error 0.1555 N between real force and predicted force which is derived by the calibration matrix. The experiment results prove that the proposed sensing method can provide triaxial force sensing on the complex 3D curved surface with good performance.