Fabric Interface with Proximity and Tactile Sensation for Human-Robot Interaction

Human-in-the-loop task involving soft contact has become common in robotic application, especially in physical human-robot interaction. In this task, it is required that robot would sense interactions with human by touching, as well as assess possibility of human approaching by proximity sensation. In addition, it is also essential to fabricate an interface so that human does not feel uncomfortable during physical interaction with robot. This paper presents an attempt on fabrication of sensing elements that can be utilized for construction of a soft interface (or a robotic skin). Each element is made from fabrics and soft materials that can sense both proximity and applied force from human's touch. In addition, each sensing element can sense the relative distance of conductive object (or human body) that is approaching the sensing element's surface, and the 2x2 contact force distribution when the object makes contact with the sensing element. By exploiting simultaneous measurement of capacitance, each fabric sensing element can smoothly switch the proximity mode and tactile mode based on position of the object. We also constructed a model that can predict variation of capacitance measurement of proximity and tactile modes during operation for further analysis. The methods and results presented in this paper can be extended to construct a larger scale of robotic skin for robot's body, and act as a platform for study human-robot interaction.