Internal Moving Mass Actuator Control for Mars Entry Guidance

An internal moving mass actuator control system is proposed for angle-of-attack and sideslip-based Mars precision entry guidance. Internal moving mass actuators provide vehicle control moments without direct interaction with the external flowfield. This enables trajectory control without destabilization concerns associated with aerodynamic flap ablation and flowfield interaction for both flap and thruster control systems. Angle-of-attack and sideslip control is proposed as an alternative to bank angle guidance for decoupling range and crossrange control for improved precision entry guidance. A new variant of the Apollo Earth return terminal guidance algorithm is presented and used to provide closed-loop attitude commands. A linear-quadratic controller with integral error action is synthesized and tuned for a Mars Phoenix-sized entry vehicle with two internal moving mass actuators for guidance command tracking. Nonlinear simulation of the controller for the eight-degree-of-freedom system demonstrates preci...