The various uncertainties of Mars environment have great impact on the process of vehicles entering the atmosphere.To improve the robustness of control system against the model errors and to reduce the computational b...The various uncertainties of Mars environment have great impact on the process of vehicles entering the atmosphere.To improve the robustness of control system against the model errors and to reduce the computational burden, an optimal feedback based tracking control law is developed. The control scheme presented in this paper determines the amplitude and the reversals of bank angle respectively in the longitudinal and lateral flight plane. At each control cycle, the amplitude of the bank angle is obtained by an optimal feedback controller to minimize tracking errors. The control gains are tuned according to the closed-loop error dynamics by using optimization methods. The bank reversals are executed if the crossrange exceeds a predetermined corridor which is designed by setting a boundary function. The accuracy and robustness of the proposed closed-loop optimal feedback based control law in tracking the reference trajectory is verified via500 deviation simulations, in which modeling errors and external disturbances are considered.展开更多
Point return orbit(PRO) of manned lunar mission is constrained by both lunar parking orbit and reentry corridor associated with reentry position.Besides,the fuel consumption and flight time should be economy.The patch...Point return orbit(PRO) of manned lunar mission is constrained by both lunar parking orbit and reentry corridor associated with reentry position.Besides,the fuel consumption and flight time should be economy.The patched conic equations which are adaptive to PRO are derived first,the PRO is modeled with fuel and time constraints based on the design variables of orbit parameters with clear physical meaning.After that,by combining analytical method with numerical method,a serial orbit design strategy from initial value design to precision solution is proposed.Simulation example indicates that the method has excellent convergence performance and precision.According to a great deal of simulation results by the method,the PRO characteristics such as Moon centered orbit parameters,Earth centered orbit parameters,transfer velocity change,etc.are analyzed,which can supply references to the manned lunar mission orbit scheme.展开更多
To expand mission capabilities needed without a proportional increase in cost or risk for exploration of the solar system,the multiple objective trajectory using low-thrust propulsion and gravity-assist technique is c...To expand mission capabilities needed without a proportional increase in cost or risk for exploration of the solar system,the multiple objective trajectory using low-thrust propulsion and gravity-assist technique is considered.However,low-thrust,gravity-assist trajectories pose significant optimization challenges because of their large design space.Here,the planets are selected as primal scientific mission goals,while the asteroids are selected as secondary scientific mission goals,and a global trajectory optimization problem is introduced and formulated.This multi-objective decision making process is transformed into a bi-level programming problem,where the targets like planets with small subsamples but high weight are optimized in up level,and targets like asteroids with large subsamples but low weight are optimized in down level.Then,the selected solutions for bi-level programming are optimized thanks to a cooperative Differential Evolution(DE) algorithm that is developed from the original DE algorithm;in addition,an sequential quadratic programming(SQP) method is used in low-thrust optimization.This solution approach is successfully applied to the simulation case of the multi-objective trajectory design problem.The results obtained are presented and discussed.展开更多
基金supported by the National Natural Science Foundation of China(11372345)
文摘The various uncertainties of Mars environment have great impact on the process of vehicles entering the atmosphere.To improve the robustness of control system against the model errors and to reduce the computational burden, an optimal feedback based tracking control law is developed. The control scheme presented in this paper determines the amplitude and the reversals of bank angle respectively in the longitudinal and lateral flight plane. At each control cycle, the amplitude of the bank angle is obtained by an optimal feedback controller to minimize tracking errors. The control gains are tuned according to the closed-loop error dynamics by using optimization methods. The bank reversals are executed if the crossrange exceeds a predetermined corridor which is designed by setting a boundary function. The accuracy and robustness of the proposed closed-loop optimal feedback based control law in tracking the reference trajectory is verified via500 deviation simulations, in which modeling errors and external disturbances are considered.
基金supported by the Open Research Foundation of Science and Technology on Aerospace Flight Dynamics Laboratory (Grant No.2012afdl005)
文摘Point return orbit(PRO) of manned lunar mission is constrained by both lunar parking orbit and reentry corridor associated with reentry position.Besides,the fuel consumption and flight time should be economy.The patched conic equations which are adaptive to PRO are derived first,the PRO is modeled with fuel and time constraints based on the design variables of orbit parameters with clear physical meaning.After that,by combining analytical method with numerical method,a serial orbit design strategy from initial value design to precision solution is proposed.Simulation example indicates that the method has excellent convergence performance and precision.According to a great deal of simulation results by the method,the PRO characteristics such as Moon centered orbit parameters,Earth centered orbit parameters,transfer velocity change,etc.are analyzed,which can supply references to the manned lunar mission orbit scheme.
基金supported by the Open Research Foundation of Science and Technology on Aerospace Flight Dynamics Laboratory of China (Grant No. 2012afdl005)
文摘To expand mission capabilities needed without a proportional increase in cost or risk for exploration of the solar system,the multiple objective trajectory using low-thrust propulsion and gravity-assist technique is considered.However,low-thrust,gravity-assist trajectories pose significant optimization challenges because of their large design space.Here,the planets are selected as primal scientific mission goals,while the asteroids are selected as secondary scientific mission goals,and a global trajectory optimization problem is introduced and formulated.This multi-objective decision making process is transformed into a bi-level programming problem,where the targets like planets with small subsamples but high weight are optimized in up level,and targets like asteroids with large subsamples but low weight are optimized in down level.Then,the selected solutions for bi-level programming are optimized thanks to a cooperative Differential Evolution(DE) algorithm that is developed from the original DE algorithm;in addition,an sequential quadratic programming(SQP) method is used in low-thrust optimization.This solution approach is successfully applied to the simulation case of the multi-objective trajectory design problem.The results obtained are presented and discussed.
