A Depth Camera-Based Soft Fingertip Device for Contact Region Estimation and Perception-Action Coupling

Abstract

As the demand for robotic applications in unconstrained and dynamic environments rises, so does the benefit of advancing the state of the art in soft robotic technologies. However, the complex capabilities of soft robots elicited by their high-dimensional, non-linear characteristics simultaneously yield difficult challenges in control and sensing. Moreover, embedding tactile sensing capabilities in soft materials is often expensive and difficult to fabricate. In recent years, however, the invention of small-scale depth-sensing cameras introduced a promising channel for soft tactile sensor design. In this work, we propose a novel soft device inspired by the human fingertip that not only utilizes a small depth camera as the perception mechanism, but also possesses compliance-modulating capabilities. We demonstrate its ability to accurately estimate contact regions upon interaction with an external obstacle, and show that the estimation sensitivity can be modulated via internal fluid states. In addition, we determine an empirical model of the device's force-deformation characteristics under simplifying assumptions, and validate its performance with real-time force matching control experiments.