Research On Rapid Trajectory Optimization And Guidance For Entry Gliding Vehicle

The rapid trajectory optimization technology can be applied to the optimization of the nominal trajectory of a gliding aircraft and overall design tasks to improve the design efficiency and reduce the preparation time before launch.At the same time,the online optimal guidance system based on trajectory rapid optimization get the real-time optimal trajectory to meet the process constraints and terminal constraints requirements,according to the current State of the aircraft,and gives the best guidance instructions,it has better autonomy,robustness,self-adaptation and high guidance accuracy.This paper focuses on the fast trajectory optimization technology for gliding aircraft and the closed-loop guidance technology based on rapid optimization.The current development situation of rapid trajectory optimization technology and the closed-loop guidance technology based on rapid optimization is surveyed in detail.The development and its trend is analyzed.Based on the characteristics of the trajectory optimization problem studied in this paper,the mathematical model is established.The reentry mathematical model is established in the semi-velocity system,and various constraints and performance indicators that should be considered in the optimization problem are analyzed.Converting the trajectory optimization problem into a convex op timization problem will greatly improve the efficiency of the solution.The core idea of sequence convexity is to obtain the optimal solution of an approximate convex problem by linearly approximating nonlinear dynamics and other nonlinear constraints.In this paper,Radau Pseudospectral Method is used to discretize the original problem,and the constraint of dynamic equation is transformed into algebraic constraint.After linearization,each convex sub-problem is solved for each iterations,and the optimal solution obtained from each iteration is taken as the next time.Iteratively linearizes the reference point until the optimal solution converges.The feasibility of the method is verified by simulation.Compared with the traditional methods based on Radau Pseudospectral Method for discrete and SQP method,the performance index is basically the same,but the solution efficiency is greatly improved.Research on closed-loop guidance method based on Receding Horizon control is studied in this paper,An optimization method based on Successive Convexification technique is used as a solution method for optimal control instructions.Considering that the open loop tracking trajectory optimization results in the trajectory optimization period have a large deviation i n the guidance process,this paper combines the traditional LQR nominal trajectory tracking method with receding horizon optimization,tracks the standard trajectory obtained in the last guidance period based on the LQR tracking method in each guidance per iod.The feasibility of the proposed method is verified by simulation.Compared with the traditional LQR trajectory tracking method,the guidance accuracy is slightly improved under the same combined deviation.