Adaptive control of projectile fin angle using piezoelectric beam actuator

The objective of this paper is to study the feasibility of using smart material to control the rotation angle of a subsonic projectile fin during flight. The fin produces maneuvering force and moment which are utilized to control the projectile. In this paper a beam model of piezoelectric actuator is used for rotating the projectile fin. The fin, which is assumed to be rigid, is rotated by a cantilever beam-based piezoelectric actuator whose both end are attached to the projectile body and the fin. An analytical model of the beam actuator is obtained by the finite element approach with each element satisfying Euler-Bernoullis theorem. A feedback linearizing adaptive control system is designed for the trajectory control of the fin angle. The controller consists of an inverse system and a high gain observer. Simulation results are presented which show that fin control is accomplished in spite of uncertainties in the system.