Direct collocation with nonlinear programming (DCNLP) for RLV's re - entry trajectory optimization is proposed. Firstly, with the attack angle and bank angle as the control variables, considering strict process and terminal constraints, the optimal control problem is set to maximize the voyage of RLV. Secondly, the optimal problem is transformed to a normal nonlinear programming problem using DCNLP, which parameters to be optimized are state variables and control variables in every node. Finally, Matlab software package SNOPT is used for solving the nonlinear programming problem. Simulation results show that the optimized re - entry trajectory satisfies the process constraints, and the terminal state can accomplish the desired target condition. The DCNLP can be coded very easily, and run faster than indirect method.%介绍了DCNLP法在可重复使用运载器再人段轨迹优化中的应用.首先以可重复使用运载器为对象,以攻角和倾侧角为控制变量,并考虑严格的终端约束和过程约束,建立了以航程最远作为优化目标的最优控制问题模型.然后采用DCNLP法将最优控制问题转化为一般的非线性规划问题,选取各节点上的状态量和控制量作为优化参数.最后应用matlab软件包SNOPT对得到的非线性规划问题进行求解.仿真结果表明,优化后的再入轨迹严格遵守过程约束,终端落点的精度也较高,且易编程实现.
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