Guidance and Control Design for a Class of Spin-Stabilized Fin-Controlled Projectiles

Abstract

This article presents a complete design concerning the guidance and autopilot modules for a class of spin-stabilized fin-controlled projectiles. The proposed concept is composed of two sections: the rapidly spinning aft part contains the charge, whereas the front part, which is roll decoupled from the aft, includes all the necessary electronic equipment and actuator devices needed for guidance and control. As far as the front section is concerned, a skid-to-turn control configuration is adopted, employing two pairs of movable trajectory correction aerodynamic surfaces, whereas a coaxial motor is added for nose roll angle positioning. The main advantage of the overall setup is that, on the one hand, it maintains the inherent dynamic stability properties of a rapidly spinning body due to the aft part, while at the same time, the front part, containing the guidance fuse, remains easy to be fit to any unguided projectile, hence transforming it into a guided one. The design of the guidance and control modules for this configuration still remains a challenging task because the rapid spinning of the body creates a heavy coupling between the normal and lateral projectile dynamics, which must be eliminated. Furthermore, the rapidly changing operating conditions, the extended flight envelope, and the limited actuator and sensor bandwidths make this task even more demanding. A thorough yet practical procedure for the treatment of the preceding issues is described in this work involving several steps, such as nonlinear modeling of the projectile dynamics, equilibrium point computation, and linear parameter-varying modeling, autopilot design as well as guidance algorithms. Finally, complete nonlinear simulations based on realistic scenarios are performed to demonstrate the robustness of the proposed solution with respect to uncertain initial launch conditions.