A composite guidance law through reference trajectory tracking for Mars entry guidance

摘要

The landing accuracy of a Mars entry vehicle will be degraded duo to uncertain factors in the atmospheric entry process and a novel composite guidance law, having a composite hierarchical framework, is presented to improve the landing accuracy in this paper. It could eliminate the constraint that maximum boundary value of uncertain factors must be known in advance in the multiple sliding surface guidance law. In the atmospheric entry process, the disturbance in the flight path angle due to the aerodynamic parameters could be estimated through a disturbance observer and be incorporated in the feedforward compensation. Other disturbances could be attenuated by the multiple sliding surface techniques. Its global stability is proven by using a Lyapunov-based approach. The guidance performance is evaluated through Monte Carlo simulations and results indicate that it could track a reference trajectory with enhanced anti-disturbance capability, leading to improve landing accuracy.