A multi-modal tactile fingertip design for robotic hands to enhance dexterous manipulation

Tactile sensing is critical for enhancing manipulation precision and versatility, but its adoption in robotic hands remains limited due to high sensor costs, manufacturing and integration challenges, and difficulties in extracting expressive and reliable contact information. In this work, we present a low-cost, easy-to-make, adaptable, and compact fingertip design for robotic hands that integrates multi-modal tactile sensors. We use strain gauge sensors to capture static forces and a contact microphone sensor to measure high-frequency vibrations during contact. These tactile sensors are integrated into a compact design with a minimal sensor footprint. From sensor characterization, we show that strain gauge sensors provide repeatable 3D force measurements in the 0-5~N range and the contact microphone sensor can captures distinct vibrotactile signatures associated with different material types. We evaluate our design with three types of manipulation tasks, including slip-aware closed-loop grasping to handle a wide range of objects, cup counting and unstacking with precise contact localization, and box selection and opening with hidden material identification. Given the expressiveness and reliability of tactile sensor readings, we show that different tactile sensing modalities can be used flexibly in manipulation, solely or together to achieve improved task performance. The design will be open-sourced on the project website: https://sites.google.com/view/tactilefingertip.