Experimental Identification and Phase-Bsed Correction of Missile Fin Actuator Dynamic Stiffness

This paper presents a method for identifying the dynamic stiffness of a missile fin actuator using a hydraulic shaker and a fin-like dummy. The actuator was mounted on a T-slot bed, and sine wave force was applied to the dummy tip. Excitation force, actuator angle, and tip acceleration were measured over a frequency range of 0-100 Hz and transformed into the frequency domain, showing high coherence. A dynamic stiffness basic expression was derived from rotational equilibrium, comprising a moment-angle term and an inertia term, showing an artificial stiffness increase above approximately 70 Hz. To correct this issue, two correction schemes are proposed: a phasebased moment-angle formulation and an accelerometer-based refinement of the inertia term. Results indicate that the phase-based correction provides a physically consistent stiffness up to 100 Hz, whereas the accelerometer-based method, while suppressing divergence, exhibits frequency dependence.