Pneumatic Soft Actuator Capable of Visuo-tactile Sensing toward an In Vitro Tongue Simulator

The deformation of the food bolus by the human tongue represents a manipulation process in which deformable objects are brought to a desired state by sensing their shape and adjusting tongue movements accordingly. This study introduces a soft actuator equipped with a visuo-tactile sensor that enables both surface shape sensing and actuation toward an in vitro tongue simulator to elucidate the mechanism of this manipulation. The proposed soft actuator employs a mechanism in which a deformable object is pressed against the palate by a pneumatically inflated balloon to form it. Shape sensing is achieved through visuo-tactile sensors featuring concentrically arranged ring patterns on the silicone rubber surface membrane of the balloons. Experimental results validated the accuracy of shape sensing, the forming capability for deformable objects, and viscoelasticity estimation using the sensing capability.