Effect of Embedded Control Surface Actuators on Active Aeroelastic Control

Abstract

In recent studies it has been shown that by designing active aeroelastic control (AAC) through the method of receptances, the flutter instabilities can be avoided and flutter boundaries can be extended via pole placement. Such an approach is advantageous because it avoids approximation of aeroelastic system matrices associated with structures and aerodynamic forces which are generally needed for control gain computation in state space. Moreover the control design is purely based on available receptance transfer functions, which represent the true aeroelastic interaction and may also be extracted or available from the embedded sensors and actuators on the aircraft. In recent years, receptance based singleinput, multiple-input and output state feedback control has been developed. In this research, the effect of the control surface dynamics (actuator dynamics) on realizing active aeroelastic control through control surface actuation is presented. The effect of actuator dynamics on the closed loop stability and flutter margins are investigated. It is shown that arbitrary selection of actuator may lead to instability of the actuator modes despite the control of aeroelastic poles for flutter suppression and flutter boundary extension. This is overcome by simultaneous control of aeroelastic and actuator poles. The formulation to achieve active aeroelastic control with multiple actuators having actuator dynamics is developed here. This also allows the selection of actuator parameters driving the control surfaces for a given cost objective. Numerical examples are presented to demonstrate the solution strategy.