A Method of Atmospheric Entry Guidance with Parachute Opening Altitude as Control Target

Abstract

The invention relates to an atmosphere entry guidance method using a parachute-opening height as a control target. The atmosphere entry guidance method comprises: (1) completing nominal trajectory design to obtain nominal guidance law uref, nominal longitudinal range sref, nominal height change rate h<.>ref, nominal resistance acceleration Dref, nominal lift force acceleration Lref, nominal to-be-flying height Htogo_ref and nominal flight path angle [gamma]ref; (2) according to the deviation of the current flight longitudinal range s, the current resistance D and the current height change rateh<.> relative to the nominal longitudinal range sref, the nominal resistance acceleration Dref and the nominal height change rate h<.>ref, and the nominal to-be-flying height Htogo_ref correspondingto the current speed, predicting the current to-be-flying height Htogo_p; (3) according to the predicted to-be-flying height Htogo_p, calculating a control compensation amount [delta]u to eliminate the deviation between the predicted to-be-flying height and the reference to-be-flying height; (4) determining the final guidance law uc by using the guidance law compensation amount [delta]u and the nominal guidance law uref obtained in the step (1); and (5) real-timely obtaining the longitudinal range s, the height change rate h<.> and the resistance acceleration D of a landing device from an atmosphere entry point to parachute-opening, generating guidance law uc, and transmitting to a landing patrol device so as to carry out closed-loop control.

Description

technical field [0001] The invention belongs to the guidance field of the thin atmosphere entry process of a small lift body in the deep space exploration planetary surface landing project, and relates to an analytical prediction correction guidance method based on a nominal trajectory. Background technique [0002] my country's first planetary exploration mission will implement planetary orbiting, landing and patrol detection through a single launch. The key to the mission is to successfully implement a soft landing on the surface of the planet. However, 18 planetary landing exploration missions have been implemented in the world at present, and only 7 of them are completely successful, with a success rate of less than 39%. It can be seen that the planetary landing exploration mission is very difficult. Among them, the entry, descent and landing process (EDL, Entry, Descent, and Landing) is the biggest challenge faced by planetary landing exploration missions. [0003] To ...

AI Technical Summary

Problems solved by technology

Compared with the reentry of the earth, the time delay of ground measurement and control during the entry process is large, the atmospheric environment on the surface of the planet is complex and changeable, and the aerodynamic parameters of the probe have large uncertainties, resulting in multiple target shooting simulations. The terminal state is widely scattered, and it is difficult to ensure that the constraints of opening the parachute are satisfied

[0004] At present, the published literature at home and abroad mainly focus on the guidance accuracy and the amount of misses as the primary control objectives, and seldom pay attention to the spread of the parachute opening height, and even less articles design guidance laws with the goal of controlling the parachute opening height.

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