Instantaneous Contact Localization on A Magnetically Transduced Tapered Whisker

Abstract

The whisker-inspired tactile sensor is advantageous for enhancing robotic perception in proximate range and darkness via non-intrusive contacts. However, localizing contact along the whisker shaft is challenging due to the non-injective mapping between tangential contacts and the resulting bending moments at the whisker base. Previous studies suggest that incorporating axial force measurements can resolve this ambiguity. In this work, we develop a magnetically transduced whisker sensor that integrates axial force sensing as an additional mechanical signal. The sensor features a tapered whisker with a custom slope and a 3-DoF suspension mechanism, enabling axial displacement at the base, which is proportional to the applied axial force. We construct a Penalized Gaussian Process model trained on synthetic data to estimate the whisker’s motion and refine it with real-data constraints. The design is compact, low-cost, and validated through simulations and real-world experiments to differentiate tangential contacts. Furthermore, we propose an optimization-based approach for estimating instantaneous contact locations. Experimental results demonstrate that the proposed method can effectively track contacts in millimeter-level accuracy with a mean error of 7.17 mm, achieving a higher accuracy with only 4.02 mm in large-deflection and close-to-base regions.