Integrated sensing and actuation of unsteady flow-induced membrane deformations*

The ability to monitor flow-induced deformation of a membrane in real time provides first-order insight into the surrounding flow field. Simple first-order quantities such as the mean camber can be linked to aerodynamic forces acting on the membrane, as well as flow field information such as the frequency and timing of vortex shedding. Coupling this with the ability to dynamically adjust membrane tension provides an opportunity for closed-loop flow control of membrane wings. In this work, a dielectric elastomer actuator is used as the wing membrane, actuated using a high voltage to dynamically vary the tension and camber of the wing. Either independently or simultaneously, the capacitance of the membrane is measured in real time using a recursive least squares (RLS) adaptive filter. Because the membrane is incompressible, the capacitance can be used to calculate in-plane strain, which in turn can be used to estimate the wing camber. The performance of the system acting solely as a sensor and as an integrated sensor/actuator is quantified in a series of benchtop and wind tunnel experiments.