Soft Inflatable Sensing Modules for Safe and Interactive Robots

Recent advancements of technologies in human-robot interaction (HRI) significantly expanded the applications of robots from specialized areas to our daily lives. However, safety is not always guaranteed in traditional robots since they are mostly made of rigid materials and structures, which cause serious injuries to humans upon physical collisions. In this letter, we propose a soft inflatable module with self-contained tactile sensing for safe HRI applications. The proposed sensing module is made of a highly stretchable elastomer skin containing embedded microfluidic tactile sensors and a rigid bone structure. The module not only actively inflates and deflates, but also detects surface contacts using microfluidic soft pressure sensors to prevent human injuries caused by unintended collisions with robots and allowing follow-up actions to be taken, such as halting and evading. This letter describes the design and fabrication of the proposed inflatable sensing module, characterizes the performance of the soft sensors with different inflation levels, and evaluates the safety aspect of the module through collision tests. Finally, we present an example of applications for the proposed system by integrating multiple modules into a robotic arm with 4 DOF. The arm was tested for evasion at different levels of contacts.