Theoretical and experimental investigations on an active control system for vertical fin buffeting alleviation using strain actuation

In the present investigation, the results obtained during the ground vibrat ion tests of a closed-loop control system conducted on a full-scale fighter to attenuate vertical fin buffeting response using strain actuation are pr esented. The experimental results are supported by numerical analysts using a finite element aeroelastic model of the structure. Two groups of actuato rs consisting of piezoelectric elements distributed over the structure were designed to achieve authority over the first and second modes of the verti cal fin. The control laws were synthesised using the linear quadratic Gauss ian (LQG) method for a time-invariant two-input, two-output (2x2 MIMO) cont rol system. Three different pairs of sensors including strain gauges and ac celerometers at different locations were used to close the feedback loop. T he results demonstrated that actual reductions of up to 18% in the root-mea n-square (RMS) values of the fin dynamic response measured by the strain tr ansducer at the critical point for fatigue at the root were achieved for th e secund mode under the most severe buffet condition.