Attitude And Orbit Control For Spacecrafts With Actuator Failures

Spacecraft have the characteristics of high cost and high risk.The great loss will be caused by the failure of the spacecraft.For example,the failures of actuators in the attitude and orbit control system,which is a key subsystem of the spacecraft,will make the spacecraft unable to complete the assigned tasks due to the decline of the attitude and orbit control ability,and even will make the spacecraft scrapped.In case of partial actuator failure,the own capability of spacecraft is adopted with priority for completing the established mission.For example,part of the established functions can be completed through the remaining actuators,and the auxiliary control of the external environment such as ultra-low orbit aerodynamics,etc.If the established functions cannot be accomplished through its own capability,other serving spacecraft must be used to achieve in-orbit maintenance.The long-range rendezvous and formation configuration maintenance are prerequisites for achieving on-orbit maintenance.Especially when actuators of serving spacecraft system also have partial failures,the control difficulty of long-range rendezvous and formation configuration maintenance is increased.Therefore,it is of great research value and practical engineering significance to carry out the research on attitude control,long-range rendezvous and formation configuration maintenance with actuator failures,focusing on the key problems concerned in practical engineering.Taking the spacecraft with actuator failures as the research object,this dissertation carries out specific and in-depth research on attitude and orbit control issues involved in engineering.For the problem that three-axis stable control cannot be achieved when partial actuator faults in the axisymmetric spacecraft,an adaptive integral sliding mode finite time rotation axis pointing control method is proposed considering that there are only two torques perpendicular to the symmetry axis.This method is to integrate the H(?)lder continuous controller with finite time stabilization,the sliding mode controller and the adaptive controller for realizing the stable pointing control of the rotation axis in the axisymmetric spacecraft,through the real time estimation and active compensation of coupling factors such as uncertain inertia,unknown external disturbance and actuator failure.For the attitude control problem of the ultra-low orbit spacecraft with partial actuator failure,the variation law of aerodynamic torque with attitude angle and aerodynamic wing angle is found through the analysis of aerodynamic characteristics based on the designed aerodynamic wing layout and an adaptive attitude control method is proposed in order to achieve stable co ntrollability of three-axis spacecraft attitude in the case of partial actuator failures.For the configuration control problem of multi spacecraft formation under the condition of limited communication and partial actuator failures,an attitude orbit coupling control law is designed based on the presented event trigger conditions through the analysis of the closed-loop system stability and the event trigger Zeno phenomenon,an event triggering mechanism coupled with state and constant value is designed by the introduced state expansion observer,which is used to overcome the influence of the unknown disturbance on the spacecraft,and an adaptive control strategy based on event triggering is proposed finally by the comprehensive consideration for the effects of actuator failure,event triggering mechanism and unknown disturbance.For the problem of far-range rendezvous trajectory planning and control under thrust fault,considering the case of coplanar orbital transfer,an optimal trajectory planning method for finite variable thrust fuel is proposed.On this basis,an optimal design scheme of trajectory transfer based on particle swarm optimization can be achieved,through the dimensionless motion state equations for coplanar orbit transfer established by polar coordinates,the continuous thrust implementation strategy based on polynomial function,and the optimization model of the probl em without trajectory terminal constraints obtained by the penalty function,respectively.Considering the case of non-coplanar orbital transfer,a trajectory planning method based on the shape approach is proposed.On this basis,a sub-optimal fast implementation scheme of trajectory transfer is obtained,which can solve the polynomial coefficients without parameter optimization under boundary constraints,through the state equation of non-coplanar orbital transfer motion established by cylindrical coordinates,the analytical expressions of trajectory radial shape and elevation angle based on inverse polynomial and trigonometric function,respectively.