Scalable Arrays of Pneumatic Sensors for Multitouch Soft Skins

Soft robotic systems necessitate accurate and reliable sensor readings to detect environmental interactions and provide precise feedback for control. To be effective, soft sensors must exhibit sensitivity, reliability, repeatability, and flexibility. A versatile approach to sensing for soft robots uses soft air-filled deformable structures with pressure transducers to detect pressure changes due to applied forces. However, the common approach of employing one pressure transducer per sensing chamber limits the scalability of this sensing approach (e.g., for large arrays able to detect touch at many locations). Here we present an approach to the design of pneumatic sensor arrays that reduces the number of required transducers. We develop mathematical models to analyze the pressure variations within the sensor arrays in response to applied forces at various locations. We also introduce a method of rapidly fabricating sensor arrays by laminating elastomeric sheets patterned with laser-cut sacrificial layers. We then use our model to optimize the geometry of the sensors and evaluate the results experimentally. Finally, we devise an algorithm capable of determining the location of multiple touches anywhere within the sensor array. This work represents a step towards the practical application of soft pneumatic sensors, particularly for robotic sensing and haptic devices, enhancing the safety of human-robot interactions.