Abstract: Abstract：To reduce the difficulties in trajectory optimization and improve the adaptability of desensitization guidance, a novel online desensitized trajectory design method is proposed for Mars entry. The weighted value of predicted terminal sail error and state sensitivity are adopted as performance indexes, which are actually convex functions of bank angle. Taking use of this property, the original optimization problem is converted into a simple dynamic optimizing process. Then, according to the mission requirement and estimated entry state, a threedegreeoffreedom desensitized trajectory that simultaneously satisfies the requirement for range and cross range can be found via iteration process. Numerical simulations show that the terminal state accuracy of the proposed method is close to the existing desensitization design.

Key words: Keywords：robust guidance, online desensitization design, mars entry guidance, desensitized optimal control