Andrew J. LombardiA closed-loop plasma actuated control scheme which relies on the ability to detect incipient flow separation is presented. It is known that the receptivity of the boundary layer increases with the onset of separation. The detection scheme therefore hinges on the ability to measure disturbances produced by the unsteady pulsing of a plasma actuator via an on-board pressure sensor and analog circuitry.The actuator introduces the disturbances into the flow at a low powered "Sense State." An on-board pressure sensor measures the real-time pressure signal atx/c = 0.08, which is then amplified and bandpass filtered around the actuator's pulsing frequency. An integrated circuit which measures the RMS of the signal serves as a means to measure the spectral energy at the pulsing frequency. When the signal reaches a sufficiently high value, set by an adjustable threshold, the actuator is triggered to a high powered "Control State" with more flow control authority. The method not only provides a precursor for flow separation, but also an indicator when conditions exist where active re-attachment control is no longer needed. This is demonstrated on a periodically oscillating airfoil which is pitched into light, medium, and deep dynamic stall.