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Optimization of variable-specific-impulse gravity-assist trajectories via optimality-preserving transformation

机译：通过最优状态保持变换优化可变特异性脉冲重力辅助轨迹

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摘要

This paper concerns optimization of fuel-optimal multi-gravity-assist trajectories based on the solutions of single-leg transfers that utilize the practical solar electric propulsion with variable specific impulse. This paper studies the optimization of fuel-optimal trajectories with multiple gravity assists and variable specific impulse. The multi-gravity-assist trajectory is composed of multiple legs each of which is solved individually and combined to provide an initial guess for the multi-leg problem. The specific impulse is taken as a control variable involved in solving the optimal control problems. To reduce the strong nonlinearity of the multi-point boundary-value problem caused by multiple gravity assists, an affine transformation on the costate variables based on single-leg transfers that preserves the fuel optimality is stated and termed optimality-preserving transformation. Secondly, the optimality-preserving transformation is applied to reformulate the first-order necessary conditions for the multi-leg transfer. As a result, the solutions of the single-leg transfers can be directly used as the initial guesses for the shooting function of the multi-leg transfer. The stated optimality-preserving transformation is readily suitable to parallel computing. Additionally, the modified logarithmic homotopy method is specifically applied in variable-specific-impulse cases. The strategy combined with these two methods is efficient in optimizing the fuel-optimal multi-gravity-assist trajectories. The realistic variable-specific-impulse NASA's Evolutionary Xenon Thruster is employed in numerical simulations considering one, two, and three gravity assists cases. As a result, this proposed strategy is demonstrated to result in significant improvement of the calculation efficiency. (C) 2020 Elsevier Masson SAS. All rights reserved.
机译：本文涉及基于使用具有可变特异性脉冲的单腿转移的单腿转移的解决方案，优化燃料最佳多重重力辅助轨迹。本文研究了具有多重重力辅助和可变特定冲动的燃料最佳轨迹的优化。多重重力辅助轨迹由多个腿组成，每个腿单独解决并组合以提供对多腿问题的初始猜测。特定的脉冲被视为涉及解决最佳控制问题的控制变量。为了减少由多重重力辅助引起的多点边值问题的强非线性，基于保留燃料最优的单腿转移的成本变量对昂贵变量的仿射变换，并称为最佳保持变换。其次，应用最优性的变换以重新定制多腿转移的一阶必要条件。结果，单腿传输的解决方案可以直接用作多腿传输射击功能的初始猜测。所述最佳保持变换易于平行计算。另外，修改的对数同型方法专门应用于可变特定的脉冲案例。该策略与这两种方法相结合，在优化燃料最佳多重辅助轨迹方面是有效的。考虑一个，两个重力辅助案例，在数值模拟中使用现实的可变特异性脉冲NASA的进化氙气推进器。结果，证明了这一提出的策略导致计算效率的显着提高。 （c）2020 Elsevier Masson SAS。版权所有。

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  • 来源
    《Aerospace science and technology》 |2020年第6期|105828.1-105828.12|共12页
  • 作者

    Chi Zhemin; Jiang Fanghua; Tang Gao;

  • 作者单位

    Tsinghua Univ Sch Aerosp Engn Beijing 100084 Peoples R China;

    Tsinghua Univ Sch Aerosp Engn Beijing 100084 Peoples R China;

    Univ Illinois Dept Comp Sci Urbana IL 61801 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
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