Finite Time Anti-Disturbance Guidance Law Design for Mars Entry

This paper considers the guidance design for Mars entry vehicles with disturbance modulation, providing a composite strategy based on drag. First, according to dynamic equations of the vehicle and combining with the definition of drag, the drag dynamic equation contained with disturbance is given. Second, in order to make sure the system obtain a better anti-disturbance performance and more quickly track speed, the finite time feedback guidance law is designed based on drag dynamic equation. With the purpose of further improving the anti-disturbance ability, a disturbance observer is designed to estimate unknown disturbance and the estimated value is used for feed-forward compensation, then a composite law is obtained. In the end, a comparison simulation is carried out to examine the efficiency and superiority of this strategy.