Analysis of predictive entry guidance for a Mars lander under high model uncertainties

Abstract

a b s t r a c tThe problem of precision landing on Mars is now considered to be an essential challenge in the planned Mars missions. The paper focused on the guided atmospheric entry as a predominant phase in achieving a desired target state, as compared with the following parachute and powered descent. The predictive algorithms for the longitudinal guidance of a low-lift entry vehicle are treated. The purpose is to investigate applicability of the predictive strategy under possible high discrepancies between the on-board dynamic model and real environment while in entry trajectory. The comparative performance analysis based on computer simulation has been made between the standard one-parametric ''shooting'' predictive algorithm and a more complex two-parametric algorithm providing lower final velocity and, thus, expanding the interval of admissible downrange. However, both algorithms display considerable degradation of downrange accuracy in the cases when the actual drag force is larger than the modelled one. An acceptable solution has been found by including to both predictive guidance schemes an identification algorithm that repeatedly adapts the on-board model to varied environment in real time scale.

Skip entry guidance using numerical predictor–corrector and patched corridor

“…More precisely, the smoothed K ρ during the down phase is recorded with respect to the height h; the relationship between K ρ and h is fitted by a polynomial function K ρ (h) before switching to the up phase; subsequently, the function K ρ (h) is used as a prior information for the trajectory prediction during the up phase. A similar philosophy was used in Hamel and de Lafontaine (2006); Kozynchenko (2011). The pseudo-code for the estimation of aerodynamic and density biases is illustrated in Algorithm 1, which implies a closed-loop system (e.g., lift and drag accelerations reported from the accelerometer).…”

“…A three-dimensional profile, including the magnitude and sign, was proposed in Fuhry (1999); Leavitt and Mease (2007); Lu (2008). Previous works also considered the potential application of planning both the angle of attack and the bank angle during the guidance (see, e.g., Gurley (1993); Kozynchenko (2011Kozynchenko ( , 2013). By comparing the predicted and prescribed ranges, a discrepancy that should be eliminated using the "corrector" was obtained.…”

Controllable set analysis for planetary landing under model uncertainties

“…To improve Mars entry precision, desensitized optimal control is adopted by minimizing the sensitivity of trajectory to entry state perturbation (Li and Peng, 2011). The effect of model uncertainties on entry trajectory and landing accuracy in Mars landing is investigated, and a comparative study of the impact of different uncertainties levels on entry is conducted (Kozynchenko, 2011). The trajectory character is also researched with initial state discrepancy and model uncertainties during Mars entry (Prabhakar and Bhattacharya, 2008).…”

Autonomous navigation method based on unbiased minimum-variance estimation during Mars entry

“…Future Mars pinpoint landing missions, such as Mars sample return, manned Mars landing and Mars base, need to achieve a pinpoint Mars landing within tens of meters to 1 km of a preselected target site; therefore, high-precision autonomous navigation and active aerodynamic lift control are essential (Levesque and de Lafontaine, 2007;Kozynchenko, 2011;Li and Peng, 2011). NASA has been seeking EDL technologies, which include hypersonic guided entry, high-precision EDL navigation technology, Mars-guided parachute, sky crane terminal descent and autonomous hazard detection and avoidance (Braun and Manning, 2007;Brand et al, 2004;Wolf et al, 2005;Chu, 2006).…”