对于跳跃式再入轨迹优化问题,通常的求解方法是不经任何分析直接约束动压、过载和热流密度,再加上控制变量滚转角的约束,往往使问题变得复杂而难以求解.基于跳跃式再入轨迹的动力学特性,将轨迹进行分段,并逐段分析路径约束的特点和内在联系,建立起它们之间的解析关系式,由此得到跳跃式再入轨迹优化问题中路径约束的串行施加策略.运用该策略可以在某些情况下减少路径约束的个数,降低优化问题的复杂度;选择优化方法时,为了兼顾全局最优性与高精度结果,采用基于粒子群优化(PSO)算法和高斯伪谱法(GPM)的两层优化策略.仿真结果表明,采用两层优化策略可以得到满足约束的高精度解,路径约束串行施加策略正确可行,优化计算结果与理论分析结论一致.
For skip reentry trajectory optimization problem,path constraints (dynamic pressure,overload and heating rate) are often enforced without analysis.Besides,roll angle also needs to be constrained.These make the optimization problem very different to solve.Based on the dynamic feature,skip reentry trajectory is divided into several phases.Characteristic of path constraints and their relationship between each other in each phase are analyzed.Analytic relations of path constraints are formulated.Then,a pipelining enforcement strategy is proposed,which may reduce the number of path constraints.Considering both the global optimality and high-accuracy of solution,a two-step optimization approach based on particle swarm optimization (PSO) algorithm and Gauss pseudospectral method (GPM) is proposed.The results indicate that the proposed optimization approach can obtain high-accuracy optimal solutions which satisfy the constraints,and the proposed pipelining enforcement strategy of path constraints is valid,numerical optimization results accord with theory analytical results.