Roll autopilot design for reentry vehicle with moving-mass control system

An improved roll autopilot for maneuvering reentry vehicles controlled by moving-mass element is presented in this paper. Since the bandwidth of the servo greatly restricts the dynamic response of the system, the parameters of the autopilot are designed associated with the damping ratio and undamped natural frequency of the servo. By configuring the dominant poles of the transfer function, an excellent dynamic response of the closed-loop system is achieved. Furthermore, the autopilot is applicable to various conditions in the flight envelope, and has good tracking ability for both roll angle and roll rate instruction. The effect of the roll control autopilot is validated by 6-DOF trajectory mathematical simulations.