Semi-analytical Mars entry guidance method

Abstract

The invention discloses a semi-analytical Mars entry guidance method. The semi-analytical Mars entry guidance method comprises the following steps that a lander for a Mars atmosphere entry stage serves as a research object, Mars atmosphere is set to be motionless relative to the Mars surface, and the definition of a Mars fixed-connection coordinate system and a three-degree-of-freedom mass centermotion equation set of the lander under the coordinate system are given; the three-degree-of-freedom mass center motion equation set of the lander under the Mars fixed-connection coordinate system isprocessed, a numerical prediction model used for terminal longitudinal range errors is obtained, the influence of centrifugal acceleration and coriolis acceleration is taken into account, and meanwhile, the prediction model is updated online to ensure high-precision longitudinal range error prediction; and predicted terminal longitudinal range errors are taken as correction objects, the principleerror generating mechanism guided by an ETPC is analyzed and improved, and analytical terminal longitudinal range error correction is designed. According to the semi-analytical Mars entry guidance method, the landing precision is significantly improved, the obtained parachute-opening point distribution is very close to the computed results obtained by high-precision NPC guidance, and the validityof the method is indicated.

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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