Application of H∞ Control Based on Mixed Sensitivity in the Electro-hydraulic Load Simulator

The electro-hydraulic load simulator is an essential rig for the performance and stability test of aircraft rudder system. Its function is to reproduce, under laboratory conditions, the aerodynamic load of the rudder system. The model of electro-hydraulic load simulator is developed and the affecting factors of extraneous force are determined. To replicate the wide spectrum of aerodynamic load when the load spring stiffness varies within a definite bound, a loading controller is designed with H^∞ mixed sensitivity approach. It´s solved by the linear matrix inequality algorithm through selecting the suitable weighted functions. It´s testified by experiments that the proposed controller can satisfy robust stability and robust performance when the load spring stiffness varies. It also can eliminate extraneous force and improve the passive loading performance with the compensation networks based on the structure invariance principle.