Research On Guidance Technology Of Reentry For Reusable Launch Vehicle

The initial reentry stage of Reusable Launch Vehicle(RLV)is the first stage of reentry process.This stage has complex flight environment,strict process constraints,and a narrow range of terminal windows,which is a grim challenge for Reentry Guidance.In this thesis,we take example RLV as the research object,refer to the Reentry Guidance method of the space shuttle,and study the guidance technology of the initial reentry section with the aim of engineering.In this thesis,the three degree of freedom particle dynamics model of RLV is first established,and its lift drag ratio and reentry constraint characteristics are analyzed.Then the constraints of the reentry process is transformed into the reentry corridor corresponding to the Drag acceleration profile.According to the change characteristics of the constraints,the reentry trajectory is divided into Temperature Control Section,Constant Drag Section and Transition Section,and the trajectory is designed in segments.After the Drag acceleration profile is obtained,the online calculation formula of the trajectory guidance parameters can be derived from the analytical formula of the section.And the tracking guidance law of the resistance acceleration profile is designed on this basis.The trajectory tracking guidance strategy is obtained by combining the lateral guidance strategy.Based on the realization of trajectory tracking guidance strategy,the sources of the range deviation when tracking the nominal trajectory are analyzed in detail,and the prediction method of the waiting distance is given.The range correction strategy based on the prediction of the range is realized by using the iterative adjusting reentry trajectory profile.After obtaining the complete Reentry Guidance strategy,a three degree of freedom integrated simulation environment is established in the C language environment.The guidance strategy is implemented in the integrated simulation environment,and the guidance strategy is comprehensively simulated,verified and evaluated.The evaluation results in the integrated simulation environment show that,the reentry guidance strategy designed in this thesis can guide RLV safely into the Terminal Area Energy Management window with high accuracy.It can adapt to the uncertainty and initial state deviation required by the design index,which achieved the design goal.