A biomimetic soft robotic pinna for emulating dynamic reception behavior of horseshoe bats

Encoding of sensory information is fundamental to closing the performance gap between man-made and biological sensing. It has been hypothesized that the coupling of sensing and actuation, a phenomenon observed in bats among other species, is critical to accomplishing this. Using horseshoe bats as a model, we have developed a biomimetic pinna model with a soft actuation system along with a prototype strain sensor for enabling motor feedback. The actuation system used three individually controlled pneumatic actuators per pinna which actuated different portions of the baffle. This prototype produced eight different possible motions that were shown to have significant effects on incoming sound and could hence function as a substrate for adaptive sensing. The range of possible motions could be expanded by adjusting the fill and release parameters of the actuation system. Additionally, the strain sensor was able to represent the deformation of the pinna as measurements from this sensor were highly correlated with deformation estimates based on stereo vision. However, the relationship between displacements of points on the pinna and the sensor output was nonlinear. The improvements embodied in the system discussed here could lead to enhancements in the ability of autonomous systems to encode relevant information about the real world.