The indirect method for the continuous low-thrust near minimum cumulative longitude orbit transfer problem is addressed.The movement of the satellite is described by the Gauss equation using the modified equinoctial e...The indirect method for the continuous low-thrust near minimum cumulative longitude orbit transfer problem is addressed.The movement of the satellite is described by the Gauss equation using the modified equinoctial elements and replacing time as the system independent variable by the cumulative longitude.The maximum principle is adapted to design the optimal control in order to minimize the final cumulative longitude, and the twopoint-boundary-value problem is derived from the orbit transfer problem.The single shooting method is applied in a numerical experiment, and the simulations demonstrate that the orbit transfer mission is fulfilled and the product of the maximal thrust and the minimum cumulative longitude is near constant.展开更多
The problem of optimal aeroassisted symmetric transfer between elliptical orbits is concerned.The complete trajectory is assumed as consisting of two impulsive velocity changes at the beginning and the end of an inter...The problem of optimal aeroassisted symmetric transfer between elliptical orbits is concerned.The complete trajectory is assumed as consisting of two impulsive velocity changes at the beginning and the end of an interior atmospheric subarc,where the vehicle is controlled via the lift coefficient and thrust.The corresponding dynamic equations are built and bounded controls are considered.For the purpose of optimization computation,the equations are normalized.In order to minimize the total fuel consumption,the geocentric radius of initial elliptical transfer orbital perigee and controls during atmospheric flight should all be optimized.It is an optimal control problem which involves additional parameter optimization.To solve the problem,a two-level optimization method denoted by ＂genetic algorithm ＋ Gauss pseudospectral method＂ is adopted：the genetic algorithm is used for parameter optimization and the Gauss pseudospectral method is used for optimal control problems.The flow chart of simulation is given.On this basis,the issue of more realistic modeling with two finite-thrust subarcs in the nonatmospheric part of the trajectory is simultaneously addressed.The orbital transfer problem is transformed to three continuous optimal control problems,and the constraints at different times are given,which are respectively solved by using the Gauss pseudospectral method.The obtained numerical results indicate that the optimal thrust control is of bangbang type.The minimum-fuel trajectory in the atmosphere consists of aeroglide,aerocruise and aeroglide.They are compared with the results of pure impulsive model,and the conclusions that a significant fuel saving will be achieved by synergetic maneuver are drawn.展开更多
为实现逆行地球同步轨道(retrograde geostationary earth orbit,retro-GEO)航天器的轨道转移,提出一种利用超同步转移轨道(super synchronous transfer orbit,SSTO)实现从地球同步转移轨道(geostationary transfer orbit,GTO)至Retro-...为实现逆行地球同步轨道(retrograde geostationary earth orbit,retro-GEO)航天器的轨道转移,提出一种利用超同步转移轨道(super synchronous transfer orbit,SSTO)实现从地球同步转移轨道(geostationary transfer orbit,GTO)至Retro-GEO轨道的轨道转移方法.分析Retro-GEO轨道转移任务的特点,并建立了相应的轨道转移动力学模型.给出传统的GTO轨道转移方案、月球借力轨道转移方案和SSTO转移方案的实施策略.最后通过仿真分析表明,SSTO轨道转移方案能有效降低轨道转移所需要的速度增量,容错率高,具备工程实施可能,可用于未来Retro-GEO轨道转移任务.展开更多
基金supported by the National Natural Science Foundation of China (10832006 60874011)
文摘The indirect method for the continuous low-thrust near minimum cumulative longitude orbit transfer problem is addressed.The movement of the satellite is described by the Gauss equation using the modified equinoctial elements and replacing time as the system independent variable by the cumulative longitude.The maximum principle is adapted to design the optimal control in order to minimize the final cumulative longitude, and the twopoint-boundary-value problem is derived from the orbit transfer problem.The single shooting method is applied in a numerical experiment, and the simulations demonstrate that the orbit transfer mission is fulfilled and the product of the maximal thrust and the minimum cumulative longitude is near constant.
基金supported by the National High Technology Research and Development Program of China(863Program)(2011AA0469)
文摘The problem of optimal aeroassisted symmetric transfer between elliptical orbits is concerned.The complete trajectory is assumed as consisting of two impulsive velocity changes at the beginning and the end of an interior atmospheric subarc,where the vehicle is controlled via the lift coefficient and thrust.The corresponding dynamic equations are built and bounded controls are considered.For the purpose of optimization computation,the equations are normalized.In order to minimize the total fuel consumption,the geocentric radius of initial elliptical transfer orbital perigee and controls during atmospheric flight should all be optimized.It is an optimal control problem which involves additional parameter optimization.To solve the problem,a two-level optimization method denoted by ＂genetic algorithm ＋ Gauss pseudospectral method＂ is adopted：the genetic algorithm is used for parameter optimization and the Gauss pseudospectral method is used for optimal control problems.The flow chart of simulation is given.On this basis,the issue of more realistic modeling with two finite-thrust subarcs in the nonatmospheric part of the trajectory is simultaneously addressed.The orbital transfer problem is transformed to three continuous optimal control problems,and the constraints at different times are given,which are respectively solved by using the Gauss pseudospectral method.The obtained numerical results indicate that the optimal thrust control is of bangbang type.The minimum-fuel trajectory in the atmosphere consists of aeroglide,aerocruise and aeroglide.They are compared with the results of pure impulsive model,and the conclusions that a significant fuel saving will be achieved by synergetic maneuver are drawn.
文摘为实现逆行地球同步轨道(retrograde geostationary earth orbit,retro-GEO)航天器的轨道转移,提出一种利用超同步转移轨道(super synchronous transfer orbit,SSTO)实现从地球同步转移轨道(geostationary transfer orbit,GTO)至Retro-GEO轨道的轨道转移方法.分析Retro-GEO轨道转移任务的特点,并建立了相应的轨道转移动力学模型.给出传统的GTO轨道转移方案、月球借力轨道转移方案和SSTO转移方案的实施策略.最后通过仿真分析表明,SSTO轨道转移方案能有效降低轨道转移所需要的速度增量,容错率高,具备工程实施可能,可用于未来Retro-GEO轨道转移任务.
