High Gain Observer for Drag Tracking in Mars Entry Longitudinal Guidance

Abstract

An extended high gain state and perturbation observer combined with feedback linearization was applied in drag tracking for Mars entry longitudinal guidance. The observer estimates the drag, the drag rate and the perturbation due to model uncertainty and disturbance for drag tracking. Mars entry simulation was performed to assess the performance of the adaptive guidance law. The results demonstrate that the proposed guidance law is robust to model error, and can recover the ideal performance of the feedback linearization control.