Fractional active robust control : Control of lightly-damped plants using the isodamping contours and the CRONE approach

This article deals with the reduction of structural vibrations. Two approaches are possible to tackle this problem, either a passive method with dampers, or an active method with actuators that are controlled in order to decrease or even cancel the vibrations in the structure. The second method is used here. The objective is to control the damping of plants that are not only lightly damped but also whose models are uncertain. The proposed methodology is based on iso-damping contours and CRONE control. The iso-damping contour is defined thanks to fractional order integration in the Nichols plane and is graduated with the value of the damping factor of the closed-loop response. The CRONE control is a robust control method that uses fractional order integration. The methodology is here applied to a multivariable plant that is an aircraft wing model made with a beam and a tank whose different levels of fillings are considered as uncertainties.