Resonant pneumatic tactile sensing for soft grippers

Soft robots capable of dexterous manipulation can enable the exploration of extreme environments. Equipping these robots with tactile sensing is a challenge, as sensors must be flexible, stretchable, and robust to environmental conditions. We present a tactile sensor design with a pneumatically driven acoustic resonator, without electronics near from the end-effector. For applications to soft grippers, we measure the resonant frequency of a soft tube undergoing stretching and bending. A small hole along the resonant tube enables contact sensing and pretouch up to 2mm away. We also measure resonant frequency for a rigid uni-axial force sensing probe. Grasping tasks utilize three sensing modalities of a soft gripper; finger pose, fingertip contact, and force in the palm all provide feedback for dexterous manipulation. We discuss and address in future work the effects of atmosphere and air flow rate on resonant frequency as well as limitations in signal processing of this sensor design.