A Semi-Analytic Mars Entry Guidance Method

Abstract

The invention discloses a semi-analytic Mars entry guidance method, comprising the following steps: taking the lander of the Mars atmosphere entry section as the research object, setting the Mars atmosphere to be stationary relative to the Mars surface, and giving the definition of the Mars fixed coordinate system and the coordinates The three-degree-of-freedom center-of-mass motion equations of the lander under the system; the three-degree-of-freedom center-of-mass motion equations of the lander under the fixed coordinate system of Mars are processed to obtain a numerical prediction model for the terminal longitudinal error, considering centrifugal acceleration and At the same time, the prediction model is updated online to ensure high-precision longitudinal error prediction; taking the predicted terminal longitudinal error as the correction object, the principle error generation mechanism of ETPC guidance is analyzed and improved, and the analysis method is designed. Terminal pitch error correction. The invention obviously improves the landing precision, and the obtained parachute opening point spread is very close to the calculation result obtained by the high-precision NPC guidance, which shows the validity of the method.

Description

technical field [0001] The invention relates to the technical field of guidance and control, in particular to a semi-analytic Mars entry guidance method. Background technique [0002] The Mars entry, descent, and landing (Entry, Descent, and Landing, EDL) process refers to the lander entering the Martian atmosphere from a height of about 125km, using the aerodynamic shape for thermal protection and deceleration, and deploying a parachute or other resistance deceleration under certain conditions The device further decelerates the lander, and then uses reverse thrust rockets, airbags, buffer legs, etc. to land safely and softly on the surface of Mars. Mars entry guidance aims to calculate guidance commands based on the lander's current motion state, reference trajectory, and target landing point parameters to drive the autopilot to control the attitude change, obtain the required aerodynamic force, change the motion trajectory, and achieve precise flight control. In recent ye...

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Problems solved by technology

[0007] The purpose of the present invention is to solve the problems of weak robustness and poor adaptability of ETPC guidance under the condition of large deviation and strong disturbance, and a large calculation amount of NPC guidance, etc., and proposes a semi-analytic entry guidance algorithm, which does not significantly increase the amount of online calculation. At the same time, the guidance accuracy is effectively improved

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