On the dynamics of flight vehicle control surfaces with inertia coupling

The influence of structure modal parameters on the dynamics of an integrated actuator and control surface system is studied in this paper. The control surface is modeled as a uniform thickness plate mounted on a push-pull hydraulic actuator. The transfer function between the command and measurement signal is formulated by including the control surface moment of inertia, actuator dynamics and most importantly, an inertia coupling term governing the control surface rigid-body motion and its flexible mode dynamics. It is shown that the resonance frequency of the integrated system is made lower by the flexible mode dynamics. However, the system performance can be improved by minimising the torsion-dominated modes.