H∞ Loop Shaping Control of Input Saturated Systems with Norm-Bounded Parametric Uncertainty

This paper proposes a gain-scheduling control design strategy for a class of linear systems with the presence of both input saturation constraints and norm-bounded parametric uncertainty. lmi conditions are derived in order to obtain a gain-scheduled controller that ensures the robust stability and performance of the closed loop system. the main steps to obtain such a controller are given. differently from other gain-scheduled approaches in the literature,this one focuses on the problem of h∞ loop shaping control design with input saturation nonlinearity and norm-bounded uncertainty to reduce the effect of the disturbance input on the controlled outputs. here,the design problem has been formulated in the four-block h∞ synthesis framework,in which it is possible to describe the parametric uncertainty and the input saturation nonlinearity as perturbations to normalized coprime factors of the shaped plant. as a result,the shaped plant is represented as a linear parameter-varying (lpv) system while the norm-bounded uncertainty and input saturation are incorporated. this procedure yields a linear parameter-varying structure for the controller that ensures the stability of the polytopic lpv shaped plant from the vertex property. finally,the effectiveness of the method is illustrated through application to a physical system: a vtol vertical taking-off landing helicopter. © 2015 renan lima pereira and karl heinz kienitz.