Optical Tactile Sensing for Aerial Multicontact Interaction: Design, Integration, and Evaluation

Distributed tactile sensing for multiforce detection is crucial for various aerial robot interaction tasks. However, current contact sensing solutions on drones only exploit single end-effector sensors and cannot provide distributed multicontact sensing. Designed to be easily mounted at the bottom of a drone, we propose an optical tactile sensor that features a large and curved soft-sensing surface, a hollow structure and a new illumination system. Even when spaced only 2 cm apart, multiple contacts can be detected simultaneously using our software pipeline, which provides real-world quantities of 3-D contact locations (mm) and 3-D force vectors (N), with an accuracy of 1.5 mm and 0.17 N, respectively. We demonstrate the sensor's applicability and reliability onboard and in real time with two demos related to, first, the estimation of the compliance of different perches and subsequent realignment and landing on the stiffer one, and second, the mapping of sparse obstacles. The implementation of our distributed tactile sensor represents a significant step toward attaining the full potential of drones as versatile robots capable of interacting with and navigating within complex environments.