Barometric Soft Tactile Sensor for Depth Independent Contact Localization

Abstract

Soft tactile sensors are a family of versatile flexible sensors aiming to replicate the sense of touch using skin-like artificial systems, with the primary function of contact localization. Such devices can rely on a multitude of physical principles and structural designs. Most implementations exploit contact-induced changes in electrical or optical resistivity, achieving good performance, but strongly limiting the range of usable materials. On the other hand, solutions relying only on structural design and delocalized sensors have yet to be shown able to achieve the same performance. In this paper, we propose a barometric soft tactile sensor that utilizes a grid of sealed cavities and delocalized barometric sensors to perform contact localization independently from the contact depth. Moreover, since the device’s function is not material-specific, we also investigate the role of compliance by testing multiple increasingly softer materials. For each material, we characterize the cavities’ sensing field and then collect the data sets to train and test a multi-layer perceptron regressor for contact localization, both with a constant and variable contact depth. The results show that we are able to lower the contact localization mean error down to 2 mm.