AcouSkin: Full Surface Contact localization Using Acoustic Waves

Contact sensing and localization capabilities that mimic human skin are highly desirable for robots. In this paper, we introduce AcouSkin, an acoustic wave based full surface contact localization system. Acoustic waves produced by piezoelectric transceivers using a monotone are coupled to surfaces turning them into an active sensor. Our system leverages information from four piezoelectric transceivers mounted on the surface of an acrylic sheet and vacuum cleaner robot bumper to localize contacts to 18 unique segments. We first characterize acoustic wave propagation based on signal and material properties and then propose hardware and software methods to realize full surface contact localization. Our results show that AcouSkin can reliably localize contact on a flat acrylic sheet with 18 uniformly spaced locations across a 54cm length with mean absolute error (MAE) of <= 1 locations using maximum likelihood estimator (MLE) and multilayer perceptron (MLP) models. On the vacuum cleaner robot bumper AcouSkin shows a zero MAE. Further, the system is also able to localize contacts made using forces as low as 2N (Newtons) and as high as 20N. Overall, AcouSkin provides full surface contact localization while requiring minimal instrumentation with easy deployment on real-world robots.