Coning motion stability and decoupling methods analysis of spinning missiles with angle-of-attack feedback autopilot

The angle-of-attack (AOA) three-loop feedback autopilot is an improved three-loop autopilot that has been widely employed in missile control systems. For spinning missiles, however, unstable coning motion can be induced by the cross-couple effect. For spinning missiles with an AOA feedback autopilot, this paper analyzes the coning motion stability with the consideration of the augmentation loop and the position of the accelerometer and compares the performance of three decoupling methods. First, a novel double-channel actuator AOA three-loop autopilot is established, and the sufficient and necessary condition of coning motion stability is proposed analytically on account of the complex system equations. The stability condition shows that the stable region of the design parameters for the autopilot shrinks as a result of the spinning condition. Moreover, methods associated with actuator dynamics, control coupling, static stability, and the decoupling method of setting the lead angle to the control system are presented to improve the stability of spinning missiles. Numerical simulations are implemented to demonstrate the accuracy of the proposed methods, whose results illustrate that the stability conditions can guide AOA autopilot design for the flight stabilization of spinning missiles.