- Clark, Robert L. and Dowell, Earl H. and Frampton, Kenneth D., Control of a three-degree-of-freedom airfoil with limit-cycle behavior,
Journal of Aircraft, vol. 37 no. 3
pp. 533 - 536 .
(last updated on 2007/04/10)
The effect of control surface freeplay nonlinearities on the closed loop performance of a three-degree-of-freedom airfoil was investigated. The controllers designed for the linear system with flap restoring force serve to reduce the limit cycle oscillations (LCO) associated with pitch and plunge while maintaining the same level of LCO in the flap response as long as the flap response is included as a performance variable in the design of the compensator. The flap LCO frequency for the open loop nonlinear system is dominated by a frequency corresponding to the lunge resonance.
Closed loop control systems;Degrees of freedom (mechanics);Oscillations;Nonlinear control systems;Control nonlinearities;