Robust Non-fragile H_∞ Control for VTOL Helicopter

In consideration of additive controller gain perturbations,a delay-dependent robust non-fragile H∞ controller for a vertical take-off and landing(VTOL)helicopter system with flight time-delays was designed based on Lyapunov stability theory and formulated in the form of linear matrix inequalities(LMIs).A descriptor system transformation was taken to derive a sufficient condition for the existence of a state feedback robust non-fragile H∞ controller.In the case of no control gain perturbations,this controller was able to ensure a larger flight time-delay.The convex optimization algorithm was introduced to obtain the minimal disturbance attenuation level and parameters of optimal H∞ controller which stabilized the closed-loop system asymptotically.Simulation results show that the designed controller has good robust and non-fragile performance.