A Jacobian vector correction method for the force calibration of EIT-based tactile sensor

In this paper, we present a Jacobian vector correction (JVC) method for calibrating tactile force in EIT-based tactile sensors. The JVC method addresses the non-uniform sensitivity distribution of EIT reconstruction by constructing a scaling vector for sensitivity correction based on the Jacobian vector. A thresholding segmentation strategy is employed to enhance the correction results within a region of interest (ROI). The proposed method achieves approximately constant sensitivity across all locations and eliminates the need for extensive data collection during force calibration. We provide a straightforward sensitivity analysis and visualizations to improve comprehension of EIT measurement properties and the calibration methodology. The effectiveness of the JVC method is evaluated through phantom experiments using various target objects with different conductivities or sizes, and on a non-array EIT-based tactile sensor composed of a porous elastic polymer and ionic liquid. The results demonstrate the ability of the JVC method to accurately capture strength information without being constrained by location dependency. Furthermore, the practicality of our proposed method is validated by integrating two calibrated flexible tactile sensors (each with a 100 cm2 area) into a robot arm platform.