Elastomer Encapsulated Pressure Sensor With Engineered Air Cavity for Force Sensing

Ground contact and force detection sensors are of critical technical importance in the realization of articulated robots capable of navigating unknown or challenging terrains. Current force sensors for robotic ground contact have limitations, including being too heavy, vulnerability to inertial noise, and lacking robustness and redundancy against failure. In this paper, we present the design, laboratory testing, and flight testing of a novel force sensor which addresses the aforementioned difficulties. The force sensor presented here is based on a custom elastomer dome with an engineered air cavity adhered to a barometric pressure sensor. Uniquely, we may tailor the sensitivity and range of the sensor by engineering the elastomer shape and the air cavity within it. Further, the large deformations incurred by the sensor are exploited to design a sensor enclosure which transfers large loads to structural members rather than onto the force sensor itself. An experimentally validated finite element model is developed to numerically predict the response of the sensor under an applied load. The model is used to perform trade studies on the geometry and material properties of the elastomer dome with a focus on developing design rules for this new type of sensor. With these simple design rules and finite element model, we design, manufacture, and test these new sensors as individuals and within arrays specifically for use on a rotorcraft robotic landing gear.