UVDtact: UV Marker-Embedded Fingertip-Like Vision-Based Tactile Sensor for Shape Reconstruction and Force Estimation

Abstract

Vision-based tactile sensors are highly promising for enabling robots to perform dexterous, contact-rich manipulation tasks by providing high-resolution tactile data. Recent studies have attempted to implement shape reconstruction and force estimation capabilities for sensors with omnidirectional sensing surfaces and a compact form factor. However, achieving a small diameter comparable to that of a human fingertip remains challenging, and integrating the multiple functionalities within the fingertip form factor poses significant challenges. In this study, we present UVDtact, a vision-based tactile sensor with a fingertip-like form factor that incorporates a switchable translucent elastomer. The proposed switchable translucent elastomer, which integrates ultraviolet (UV) ink and a translucent elastomer, decouples tactile images for shape reconstruction and force estimation. The independent tactile images ensure that shape reconstruction remains unaffected by UV markers, making them visible when needed, thereby enabling effective force estimation. For shape reconstruction, we leverage the darkening effect of the translucent elastomer in response to tactile stimuli and introduce a calibration method that utilizes this effect in an all-around curved sensor configuration. Furthermore, we validate that embedding UV markers enhances tactile features, improving force estimation performance while preserving the quality of tactile images used for shape reconstruction. By integrating various tactile sensing capabilities into a compact, fingertip-like design, UVDtact contributes to developing robotic systems with human-like dexterity.