S-BUN: Soft Bifunctional Utility Module for Robot Sensing and Signaling

Conventional approaches in robotics for perceiving the environment and signaling the robot’s state or intention for human-robot interaction involve the use of separate sensing and signaling systems. This can sometimes result in high costs and complex system installations. In this study, we propose an alternative approach, integrating both robot sensing and signaling mechanisms into a single utility module (called S-BUN, Soft Bifunctional Utility module for robot sensing aNd signaling). Soft material (Ecoflex 00-10 silicone) is used to form its bun-like structure with a central cavity filled with a NaCl solution. Inspired by honeycombs, the module’s surface incorporates a hexagonal pattern to enhance structural robustness. The design of S-BUN enables it to function as a sensor for both non-contact proximity and touch sensing, utilizing the NaCl solution. Additionally, it serves as a signaling mechanism to indicate the robot’s state through the active inflation and deflation dynamics of the module, simulating lifelike breathing patterns. Through our experiments, we present S-BUN’s capabilities in proximity and touch sensing, including its ability to discern various touch intensities. Finally, we demonstrate the application of S-BUN in the context of reactive behavioral control for a crawling robot and human-robot interaction scenarios.