Normal acceleration response to canard control with wind for spin-stabilized projectiles

Abstract

In this investigation, the normal acceleration response to the control inputs of spin-stabilized projectiles considering the atmospheric wind with the coupled effects of canard control, gravity, and aerodynamic forces, being an important reference for the guidance design of low-cost guided projectiles with less measurement information (only translational motion), is deduced and analyzed. Based on the approximate formulas predicting the angle of attack under canard control and considering the atmospheric wind obtained by a linear model of the pitch and yaw motion, estimated expressions for the normal acceleration response to canard control are deduced and analyzed. To analyze the cross-coupling between pitch and yaw and simplify the design of guidance and control, the acceleration response is divided into controllable and uncontrollable parts. The phase shift between the controllable acceleration response and the direction of the control input is defined to represent the coupling effect between the pitch and the yaw; this is found to be strongly dependent on the projectiles' state parameters rather than the control parameters. The results indicate that the acceleration and phase are dramatically altered under different control directions. This condition adversely affects guidance and control because uncontrollable directions arise when the deflection angle is smaller than the critical angle.