A Robust Controller for Electrohydraulic Drives

Highly maneuverable aircraft has redundant electrohydraulic actuators that generate the forces to drive the aircraft control surfaces. Two problems are important in these actuators. First, during reconfiguration of the actuator channels the hydraulic system works in the full range of its parameters. It leads to strongly nonlinear models of the redundant servo. Second, the frequency bandwidth of elements, which are located in the feedback loop of the servo, should be as wide as possible. Therefore, it is necessary to choose proper control method for actuator, where the controller of control system adjusts the set point signal. The advanced control methods can ensure the new quality of the systems. The new, advanced methods can cope with such problem in practical applications. There are available: adaptive methods, predictive methods, etc. and first of all, the robust control methods. These methods are robust on external disturbance. The causes of disturbances are very different: the inaccuracy in the mathematical and simulation model, the change of the operation point, the weather and temperature conditions, etc. We have designed such models in the Matlab/Simulink environment and we divided the full actuator into small subsystems.