Consider unobservable uncertain parameters using radio beacon navigation during Mars entry

This paper presents a navigation algorithm based on the extended consider Kalman filter (ECKF) to mitigate the adverse effects of unobservable uncertain parameters using radio measurements during Mars entry phase. Consistency of the Mars entry navigation using a radio beacon navigation scheme is also demonstrated. A nonlinear consider approach is utilized by incorporating the covariances of the unobservable uncertain atmospheric density and the ballistic coefficient into the state estimate covariance; parameters are specifically not estimated directly to improve the navigation accuracy and robustness during the Mars entry phase. Perturbation is introduced to analyze the navigation state errors from each unobservable uncertain parameter. Numerical simulations show that the presented ECKF-based navigation algorithm is more accurate and robust than the augmented extended Kalman filter for unobservable uncertain parameters.