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Fatigue-mitigating controller design for a slender flexible antenna

In this paper the problem of fatigue mitigation in a slender flexible antenna has been addressed. The structure is subject to wind loads, which cause continuous stress cycles, giving rise to structural fatigue and breakage and reducing the service life. A robust active controller is introduced with the aim to reduce the amplitude of the stress cycles, despite model uncertainties; in particular an output feedback μ-controller has been designed, using as feedback variables the absolute accelerations of some points along the structure. The effectiveness of the control scheme has been evaluated by means of the Miner's index for the most significant structural elements. The performance has been compared with that of a passive mass damper. Simulations show the effectiveness of the μ-controller.