LPV Modeling and Tracking Control of Dissimilar Redundant Actuation System for Civil Aircraft

Dissimilar redundant actuation systems (DRAS) are in practice in advanced aircraft in order to increase reliability and to resolve the actuator failure issue due to common cause. This paper addresses the problem of force fighting that occurs due to dynamics mismatch of two dissimilar actuators in DRAS and provides a method to achieve precise tracking of aircraft control surface. The nonlinear system dynamics are first transformed into linear parameter varying (LPV) form using recursive least square (RLS) method. The LPV observer based controller is then designed to synchronize the positions of dissimilar actuators in DRAS and to drive the control surface smoothly. By applying linear matrix inequalities (LMIs), parameter dependent Lyapunov function (PDLF) is obtained to achieve global stability and to compute the controller and observer gains. To test controller according to real flight condition, an external disturbance signal that acts as air load is applied at the control surface input. Several simulations on the nonlinear system validate the dominant performance of proposed controller as compared to the existing methods in literature.