| The recycling of the first-stage rocket by means of the brake deceleration of the rocket reversing engine has been proved to be feasible technically,and the cost of single launch can be greatly reduced.The flight height span of the first-stage rocket is wide during the reentry,also the engine thrust during work is intermittent.Beyond this,uncertain aerodynamic parameters,initial state deviation and external interference exist in trajectory control.Against these characteristics when the first-stage rocket reentry the atmosphere,the research and analysis of its related trajectory design and guidance law design are carried out in this paper.Firstly,the trajectory optimization of the entire reentry section is carried out by using the pseudo-spectral method.Taking fuel consumption as the performance index,the standard trajectory of reentry that meets the process and terminal constraints and saves the most fuel consumption is obtained.Secondly,LQR method is used to study the tracking guidance for the near ground segment.The simulation results show that the designed guidance law has good robustness and can track the standard trajectory well.Subsequently,the motion characteristics of the upper air segment were analyzed,and the sensitivity of the trajectory parameters to reentry conditions was studied.Aiming at the problem that the upper air segment interference had a great impact on the landing site deviation,a new control algorithm based on the prediction-correction idea was proposed,which could effectively control the landing point to reach the predetermined area.Finally,the overall scheme of the first-stage rocket in vertical landing is put forward.In this paper,the first-stage rocket is analyzed from reentry to vertical soft landing in a fixed point,the reentry motion model is established,the overall guidance scheme is proposed,and the guidance algorithm is simulated and analyzed.The above work can provide reference for the research on rocket recycling in China. |
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