Numerical and Experimental Analyses of a Smart Fin Using Piezoelectric Actuator

Abstract

This paper introduces the comprehensive design of a thin piezoelectric-driven fin. Because of its hinge and flexible spar component having a low torsional stiffness with a thin composite actuator, the divergence speed is also predicted to be low, which is ascertained by a wind-tunnel test. As the divergence is related to the first pitch mode, the control input magnitude may be significantly reduced at the divergence speed. An improved design of the fin is also suggested to ensure its operability up to Mach 0.6. Its equivalent aeroelastic analysis is conducted by rational function approximation, and a linear quadratic regulator control law is designed using a steady-state Kalman filter with disturbance and an integral state for the tip deflection state augmentation. Both open- and closed-loop simulations are conducted while considering the input voltage saturation and other nonlinear losses in the actuator. In the relevant simulation, it is shown that a sufficient amount of pitch rotation can be achieved without any overshoots while consuming half of the zero-load voltage. Additionally, an external disturbance such as a gust can be sufficiently suppressed by increasing the closed-loop bandwidth.