Re-entry trajectory optimization using a multiple- interval Radau pseudospectral method
HAN Peng ,SHAN Jia-yuan,MENG Xiu-yun ( Key Laboratory of Dynamic and Control of Flight Vehicle,Ministry of Education, Beijing Institute of Technology,Beijing 100081,China)
Aiming at increasing the calculation efficiency of the pseudospectral methods,a multiple-interval Radau pseudospectral method ( RPM) is presented to generate a reusable launch vehicle ( RLV) 's optimal reentry trajectory. After dividing the optimal control problem into many intervals,the state and control variables are approximated using many fixed-and low-degree Lagrange polynomials in each interval. Convergence of the numerical discretization is then achieved by increasing the number of intervals. With the application of the proposed method,the normal nonlinear programming ( NLP) problem transcribed from the optimal control problem can avoid being dense because of the low-degree approximation polynomials in each interval. Thus,the NLP solver can easily compute a solution. Finally,simulation results show that the optimized re-entry trajectories satisfy the path constraints and the boundary constraints successfully. Compared with the single interval RPM, the multiple-interval RPM is significantly faster and has higher calculation efficiency. The results indicate that the multiple-interval RPM can be applied for real-time trajectory generation due to its high efficiency and high precision.
【CateGory Index】： V448.235