Dynamic stiffness enhancement of a flight control actuator using control techniques

In flight control systems, electro-hydraulic actuators are responsible for moving the aircraft primary control surfaces under boundary conditions defined by time and frequency response requirements and at the same time preventing control surface flutter when mass balancing strategies are not feasible. The flutter prevention is translated into a set of dynamic stiffness and dynamic damping requirements [1] for the hydraulic actuator. This work aims to investigate different actuator's position control strategies seeking compliance with performance requirements while enhancing the actuator's dynamic stiffness. Actuator performance is evaluated for classic controllers and a modern control approaches using an LQR control strategy and a linear reduced-order observer. This work will show the benefits of applying modern control techniques that contribute to an increase in the actuator dynamic stiffness.