Distributed, Embedded Sensing for Quasi-Static Shape Control of Wings

"An innovative sensor grid of shape-memory alloy wires is proposed to sense the shape of an aerodynamic surface. Shape memory alloys change resistance when deformed and they can thus be used as strain-sensors. The grid is formed by embedding a number ofshape memory alloy wires in an epoxy as one of the layers in a composite laminate. When encapsulated in an appropriate strain-gauge-like material, the grid can also be glued to the outer surface of the aerodynamic surface. Sensor wiring is significantlysimplified by only sensing resistance changes along the outer boundary of the grid. An innovative algorithm is proposed that will determine the grid-point-to-grid-point resistance using the "boundary-sensed" resistance changes. Assumed mode methods andother techniques are proposed to extract the shape of the aerodynamic surface from the measured resistance changes.In Phase I rectangular specimens will be fabricated and tested under cantilevered boundary conditions to verify feasibility. Phase I will also develop the shape-prediction algorithms. These algorithms will be implemented on DSPs or CPLDs in Phase II, inwhich a scaled wing model will either be constructed or supplied by the Air Force for instrumentation with the sensor-grid. In Phase II wind-tunnel tests will be performed and quasi-static shape prediction capability will be confirmed using otherdisplacement sensors or optical techniques. The proposed technology has wide