Study On The Hybrid Control Method For The Attitude Maneuver Of Flexible Spacecraft With Multiple Mode Liquid Sloshing

In order to complete the complex long time space mission, the modern spacecraft needto carry large amounts of liquid fuel, and the liquid mass has large proportion of satellitetotal mass. The mass increase of the liquid fuel would easily lead to the liquid sloshing inthe fuel tank, and the sloshing might couple with the attitude motion and the vibration ofthe flexible appendages, that will affect the stability of spacecraft and cause the failure ofthe launch for spacecraft. Therefore, it is necessary to guarantee the attitude stabilization ofthe liquid-filled flexible spacecraft, at the same time, to suppress the sloshing of the fueland vibration of flexible appendage.In this thesis, the coupled dynamics modeling of the large flexible liquid-filledspacecraft with multiple mode liquid sloshing and the hybrid control method for large angleattitude maneuver are studied. In the process of dynamics modeling, the rigid-flexible-liquid-control coupling problems are fully considered. The main research contents andresults of this dissertation are shown as follows:(1) The coupled dynamics equations of the three-axis stabilized liquid-filled spacecraftare established using theorem of moment of angular momentum. The sloshing liquiddynamics is modeled as the equivalent two-mode spring-mass and incorporated with thecoupled spacecraft dynamical model. The control method is designed based on the adaptiveoutput-feedback controller and multi-mode shaped input controller to control the spacecraftlarge attitude maneuver and simultaneously suppress the liquid fuel sloshing. The numericalresults show the controller is irrelevant to the inertia term of the spacecraft, and has goodrobustness to the external disturbance. The multiple mode ZVD input shaper can effectivelysuppresses the sloshing of liquild for the spacecraft.(2) The partially liquid-filled spacecraft dynamics system is typical under-actuatedsystem. The adaptive sliding mode control law is designed for this kind of under-actuatedsystem, and Lyapunov stability analysis guarantees that all system trajectories reach andremains on the sliding mode surface. And, the state observer is designed to estimate thetwo-mode of the sloshing liquid. Then, the corresponding hybrid controller is designed byadding the input shaper into the control system. The numerical results show the adaptivesliding mode control law has more excellent control accuracy and robustness than theconventional controllers for the partially liquid-filled spacecraft. (3) For an in-orbit fuel-filled spacecraft with one flexible solar panel, the attituderesponses of the fuel-filled flexible spacecraft subjected to the thermal bending momentduring eclipse transitions are investigated. The influence of thermal bending moment on thestability of the spacecraft is analyzed. The flexible solar panel is modeled as a cantileverEuler-Bernoulli beam, the governing equations of motion for this interaction system arefounded by using Lagrange’s principle and the law of conservation of angular momentum.Numerical results show that effect of thermal payload on precision of the attitude motioncan’t be ignored. Then, we design the adaptive sliding mode law with actuator saturationand the positive position feedback control technique to control the attitude disturbance. Thepiezoelectric materials are also utilized in the active control for the flexible structure, andan inner loop Positive Position Feedback Controller is designed. Numerical results showthat the hybrid control method reaches the control precision of the attitude maneuver andsuppressed the jitter and liquid sloshing of the spacecraft, when considering the nonlinearsaturation constraint.(4) The dynamics modeling and vibration suppression of the large flexible fuel-filledspacecraft are investigated. The large flexible appendage is modeled as a nonlinearEuler-Bernoulli beam, and the nonlinear dynamics equations are established by usingLagrange method. In view of the complexity of the control equation, the dynamics systemof the flexible liquid-filled satellite is divided into the slow and fast subsystems using thesingular perturbation theory. In order to improve the control precision, the hybrid controlmethod of thrusters and reaction wheels is designed for the slow dynamic subsystem. Forthe fast subsystem, the Lyapunov approach control law is designed using piezoelectricmaterials, and the jitter of flexible appendage is suppressed in a short time. The simulationresults show the effectiveness of the proposed hybrid controller.