A hybrid control approach for pole assignment to second-order asymmetric systems

Structural modification in the form of adding mass and stiffness (and sometime damping) as a means of passive control to assign desirable poles and zeros for symmetric systems has been extensively studied. Pole and zero assignment by means of active control has also attracted much research. Assignment of poles to stabilise second-order damped asymmetric dynamic systems using structural modifications and state-feedback control, respectively, was carried out recently. It was found that the former is often incapable of assigning complex poles with negative real parts for asymmetric systems while the latter is nearly always capable of doing that. However, the gains required to assign poles with negative real parts using active control can be high. This paper presents a two-stage passive (structural modification) and active (state-feedback) combined control approach to assign complex poles with negative real parts to damped asymmetric dynamic systems to suppress flutter instability. This hybrid approach is motivated by possible restriction to gains of actuators and cost of sole active control. Simulated numerical examples show its effectiveness over the individual control strategies of passive control and active control.