月球软着陆下降轨迹与制导律优化设计研究

Design and Optimization of the Descending Trajectory and Guidance of Lunar Soft-Landing

对月球软着陆全过程三阶段下降轨迹和制导律进行了优化设计研究,结合工程实际给出了月球软着陆飞行轨迹初步方案。制动段基于均匀球体三维动力学模型,获得一种燃料次优解析制导律;该制导律通过单步优化得到了推力角控制量的解析形式,并在推力角中引入前馈项用以消除近月点初始偏差。接近段采用平面月球模型,利用重力转弯技术,得到了解析形式的最优开关制导律。着陆段以安全性为首要目标,基于垂直降落模型,采用程序控制策略,研究了等效连续变推力制导方法。最后,分别对三阶段下降轨迹和制导律进行了算例分析,给出了软着陆全过程飞行参数变化曲线。结果表明,软着陆下降轨迹和制导律方案的设计和优化是可行的。

This paper designed and optimized the descending trajectory and guidance laws for lunar descent,in which the engineering constraints were considered.The braking phase of soft-landing introduced a three-dimensional regular spherical model so as to derive a fuel sub-optimal analytical guidance law by one-step optimization.For this guidance law,the analytical controllers of two thrust angles were obtained.Moreover,two feedforward items were introduced into the controllers to eliminate the initial descending er...