An extended-state-observer(ESO) based predictive control scheme is proposed for the autopilot of lunar landing.The slosh fuel masses exert forces and torques on the rigid body of lunar module(LM),such disturbances wil...An extended-state-observer(ESO) based predictive control scheme is proposed for the autopilot of lunar landing.The slosh fuel masses exert forces and torques on the rigid body of lunar module(LM),such disturbances will dramatically undermine the stability of autopilot system.The fuel sloshing dynamics and uncertainties due to the time-varying parameters are considered as a generalized disturbance which is estimated by an ESO from the measured attitude signals and the control input signals.Then a continuous-time predictive controller driven by the estimated states and disturbances is designed to obtain the virtual control input,which is allocated to the real control actuators according to a deadband logic.The 6-DOF simulation results reveal the effectiveness of the proposed method when dealing with the fuel sloshing dynamics and parameter perturbations.展开更多
The response of fuel-tank-sloshing to aircraft maneuver is a difficult mathematical problem to be solved. Beginning with setting up the mechanical model and the respective mathematical model, this paper uses both F.E....The response of fuel-tank-sloshing to aircraft maneuver is a difficult mathematical problem to be solved. Beginning with setting up the mechanical model and the respective mathematical model, this paper uses both F.E. and B.E.M. to imitate the sloshing process. The paper has developed some special techniques to deal with strong nonlinear characteristics, and provided satisfactory numerical results of displacements and stress for low frequency, resonance, high frequency and fuel tank dynamic response characteristics. The program not only assures convergence and stability of the solution, but also has the function of graphic display. It is a valuable technique to deal with the strong nonlinear oscillation of fuel tank with large amplitude and moving boundary condition on free surface.展开更多
为研究燃料储罐纵荡过程内部液体最大冲击力随储罐内部液体的充注率、容积及液体的黏度、密度、加速度等参数变化的特性,采用Volume of Fluid方法建立燃料储罐模型,采用单一变量法对不同充注率和容积下的罐内液体冲击进行数值模拟,分析...为研究燃料储罐纵荡过程内部液体最大冲击力随储罐内部液体的充注率、容积及液体的黏度、密度、加速度等参数变化的特性,采用Volume of Fluid方法建立燃料储罐模型,采用单一变量法对不同充注率和容积下的罐内液体冲击进行数值模拟,分析参数变化对最大液体冲击力的影响,并对最大液体冲击力与惯性力的关系进行多项式拟合。结果表明:最大液体冲击力出现时刻随储罐容积的增大而滞后,随充注率的增大而提前;最大液体冲击力不受容积、黏度、密度和加速度等参数的影响,与惯性力的比值与充注率呈4次多项式关系。展开更多
The fuel slosh in the storage tanks affects the attitude dynamics of the liquid-filled spacecraft during orbit transferring. To describe the interactions between the fuel slosh dynamics and the spacecraft attitude dyn...The fuel slosh in the storage tanks affects the attitude dynamics of the liquid-filled spacecraft during orbit transferring. To describe the interactions between the fuel slosh dynamics and the spacecraft attitude dynamics, a novel nonlinear dynamic model for three-axis liquid-filled spacecraft is presented, and in this paper, the multi-body dynamics method is utilized. In this model, the fuel slosh is represented by the motions of an equivalent sphere pendulum, and the fuel slosh is underactuated. The proposed dynamics model meets the demand of attitude controller design of liquid-filled spacecraft. Then, a nonlinear proportional-plus-derivative (PD) type controller is designed for the proposed model based on the Lyapunov direct approach. This controller can suppress the fuel slosh and stabilize the attitude of the liquid-filled spacecraft. Numerical simulations are presented to verify the effectiveness of the proposed nonlinear dynamic model and the designed underactuated controller when compared with the conventional control scheme.展开更多
目的研究燃油在汽车油箱中的晃动规律,为汽车油箱的结构可靠性设计和汽车燃油的稳定供给提供参考和依据。方法建立某款汽车油箱的几何模型,利用VOF(volume of fluid)方法进行数值模拟。采用控制变量法,对比分析有无隔板、不同冲击加速...目的研究燃油在汽车油箱中的晃动规律,为汽车油箱的结构可靠性设计和汽车燃油的稳定供给提供参考和依据。方法建立某款汽车油箱的几何模型,利用VOF(volume of fluid)方法进行数值模拟。采用控制变量法,对比分析有无隔板、不同冲击加速度、不同充液比对燃油晃动及油箱壁面所受压力的影响。结果无隔板、较大冲击加速度的情况下,燃油晃动更为剧烈,吸油管出现瞬间吸空现象,导致燃油供给不稳定,油箱受到的压力更大,影响油箱的结构可靠性。较小充液比的情况下,由于燃油晃动,吸油管容易出现瞬间吸空现象,导致燃油供给困难。结论汽车油箱采用隔板、保持较小的冲击加速度和较大充液比有利于防止吸油管瞬间吸空,从而保证燃油的稳定供给。充液比太大会造成油箱壁面所受压力增大,因此,应该保持合理的充液比。展开更多
基金Project(020301)supported by the Manned Spaceflight Advanced Research,ChinaProject(14JJ3024)supported by Hunan Natural Science Foundation,China
文摘An extended-state-observer(ESO) based predictive control scheme is proposed for the autopilot of lunar landing.The slosh fuel masses exert forces and torques on the rigid body of lunar module(LM),such disturbances will dramatically undermine the stability of autopilot system.The fuel sloshing dynamics and uncertainties due to the time-varying parameters are considered as a generalized disturbance which is estimated by an ESO from the measured attitude signals and the control input signals.Then a continuous-time predictive controller driven by the estimated states and disturbances is designed to obtain the virtual control input,which is allocated to the real control actuators according to a deadband logic.The 6-DOF simulation results reveal the effectiveness of the proposed method when dealing with the fuel sloshing dynamics and parameter perturbations.
文摘The response of fuel-tank-sloshing to aircraft maneuver is a difficult mathematical problem to be solved. Beginning with setting up the mechanical model and the respective mathematical model, this paper uses both F.E. and B.E.M. to imitate the sloshing process. The paper has developed some special techniques to deal with strong nonlinear characteristics, and provided satisfactory numerical results of displacements and stress for low frequency, resonance, high frequency and fuel tank dynamic response characteristics. The program not only assures convergence and stability of the solution, but also has the function of graphic display. It is a valuable technique to deal with the strong nonlinear oscillation of fuel tank with large amplitude and moving boundary condition on free surface.
文摘为研究燃料储罐纵荡过程内部液体最大冲击力随储罐内部液体的充注率、容积及液体的黏度、密度、加速度等参数变化的特性,采用Volume of Fluid方法建立燃料储罐模型,采用单一变量法对不同充注率和容积下的罐内液体冲击进行数值模拟,分析参数变化对最大液体冲击力的影响,并对最大液体冲击力与惯性力的关系进行多项式拟合。结果表明:最大液体冲击力出现时刻随储罐容积的增大而滞后,随充注率的增大而提前;最大液体冲击力不受容积、黏度、密度和加速度等参数的影响,与惯性力的比值与充注率呈4次多项式关系。
基金Sponsored by the Innovative Team Program of the National Natural Science Foundation of China ( Grant No. 61021002)
文摘The fuel slosh in the storage tanks affects the attitude dynamics of the liquid-filled spacecraft during orbit transferring. To describe the interactions between the fuel slosh dynamics and the spacecraft attitude dynamics, a novel nonlinear dynamic model for three-axis liquid-filled spacecraft is presented, and in this paper, the multi-body dynamics method is utilized. In this model, the fuel slosh is represented by the motions of an equivalent sphere pendulum, and the fuel slosh is underactuated. The proposed dynamics model meets the demand of attitude controller design of liquid-filled spacecraft. Then, a nonlinear proportional-plus-derivative (PD) type controller is designed for the proposed model based on the Lyapunov direct approach. This controller can suppress the fuel slosh and stabilize the attitude of the liquid-filled spacecraft. Numerical simulations are presented to verify the effectiveness of the proposed nonlinear dynamic model and the designed underactuated controller when compared with the conventional control scheme.
文摘目的研究燃油在汽车油箱中的晃动规律,为汽车油箱的结构可靠性设计和汽车燃油的稳定供给提供参考和依据。方法建立某款汽车油箱的几何模型,利用VOF(volume of fluid)方法进行数值模拟。采用控制变量法,对比分析有无隔板、不同冲击加速度、不同充液比对燃油晃动及油箱壁面所受压力的影响。结果无隔板、较大冲击加速度的情况下,燃油晃动更为剧烈,吸油管出现瞬间吸空现象,导致燃油供给不稳定,油箱受到的压力更大,影响油箱的结构可靠性。较小充液比的情况下,由于燃油晃动,吸油管容易出现瞬间吸空现象,导致燃油供给困难。结论汽车油箱采用隔板、保持较小的冲击加速度和较大充液比有利于防止吸油管瞬间吸空,从而保证燃油的稳定供给。充液比太大会造成油箱壁面所受压力增大,因此,应该保持合理的充液比。
