Acoustic Soft Tactile Skin (AST Skin)

Acoustic Soft Tactile (AST) skin is a novel soft-flexible, low-cost sensor that can measure static normal forces and their contact location. This letter presents the design, fabrication, and experimental evaluation of AST skin. The proposed AST skin has some Acoustic channels(s) (ACs) arranged in parallel below the sensing surface. A reference acoustic wave from a speaker unit propagates through these ACs. The deformation of ACs under the contact force modulates the acoustic waves, and the change in modulation recorded by a microphone is used to measure the force magnitude and the location of the action. We used a static force calibration method to validate the performance of the AST skin. Our two best AST configurations are capable of (i) making more than 93% of their force measurements within $\pm$ 1.5 N tolerances for a range of 0-30 N and (ii) predicting contact locations with more than 96% accuracy. Furthermore, we conducted a robotic pushing experiment with the AST skin and an off-the-shelf Xela uSkin sensor, which showed that the AST skin outperformed the Xela sensor in measuring the interaction forces. With further developments, the proposed AST skin has the potential to be used for various robotic tasks such as object grasping and manipulation.