临近空间太阳能飞机能量最优飞行航迹规划方法展望

General planning method for energy optimal flight path of solar⁃powered aircraft in near space

临近空间太阳能飞机是低速临近空间飞行器中一种极具发展潜力的技术途径,有望成为一个理想的区域通信、中继和运输平台。实现N×24小时能源闭环的超长航时飞行,是发展临近空间太阳能飞机的核心问题,也是形成“区域保持+时间持久”特色能力的关键。能量最优航迹规划方法是解决临近空间太阳能飞机跨昼夜能量闭环难题的有效技术方向。当前临近空间太阳能飞机能量最优航迹规划方法可分为2类:不考虑风场变化的能量最优航迹规划方法和不考虑大范围高度变化的能量最优航迹规划方法。分别对这2类问题的研究成果进行了分析与讨论,考虑不同处理框架给实际工程应用带来的困难与挑战,认为未来应统一考虑太阳辐射、空间高度和风场变化,并融合重力势能与梯度风场对太阳能飞机临近空间持久驻留能量变化的影响,开展基于强化学习框架的太阳能飞机能量最优“通用”飞行航迹规划方法研究。为此,有必要开展临近空间风场环境表征与重构、临近空间梯度风场对太阳能飞机滑翔轨迹能量影响分析、最优飞行航迹示教轨迹生成与分类、基于示教轨迹的太阳能飞机强化学习框架构建等关键技术研究。可为设计太阳能飞机能量最优航迹规划方法提供参考,为规划太阳能飞机研究技术路线提供支撑。

Solar-powered aircraft is one of the most promising technical route for the development of low-speed aerial vehicle in near space,and is expected to be an ideal platform for regional communication,relay and transportation.N×24-hour energy closed loop is the crucial problem for the development of near space solar-powered aircraft,and is also a key technology for aircraft to have the ability of“regional maintenance&time sustainability”.The energy optimal flight path planning method is an effective technical route to solve the problem of day-night energy closed-loop of solarpowered aircraft in near space.Currently,there are two methods for energy optimal flight path planning:one is the method without considering the change of wind field,and the other is the method without considering the change of large-scale altitude.Analysis and comment are given to the research results of these two methods.In order to conquer the difficulties and challenges brought by these two different processing frameworks in practical engineering applica⁃tion,suggestion is proposed to build a uniform framework based on reinforcement learning to form a“general”flight path planning method.This framework should consider the changes of solar radiation,space altitude and wind field,and also the effects of energy stored by gravity potential and energy harvested from wind shear.The key technologies to achieve this aim are analyzed:The environmental characterization and reconstruction of wind field;the impact of near space gradient wind field on the energy of solar aircraft glide trajectory;The generation and classification of opti⁃mal flight path demonstration trajectory;the construction of solar aircraft reinforcement learning framework based on demonstration trajectory.This paper provides theoretical support for the design method of energy optimal flight path planning,and technical support for realization of high-altitude long-endurance flight.