Research On Attitude Control Of Flexible Spacecraft Considering Dynamic Characteristics Of Actuator

During rapid large-angle maneuver of flexible spacecraft,attitude stability and accuracy will be affected by the vibration of the flexible attachment that is caused by its own characteristics.This paper focuses on flexible spacecraft attitude rapid maneuver and stability considering the dynamic characteristics of actuator.First,the dynamic and kinematic modeling of a spacecraft system with large flexible attachments is studied.The dynamic model of the flexible spacecraft is established based on the Kane method considering the dynamic characteristics of actuator.Next,the vibration suppression strategy for flexible spacecraft is studied separately.Two representative vibration suppression methods are studied: the positive position feedback method and the input molding method.In the former,the modal coordinates of the flexible structure are directly fed back to the compensator,and the active damping of the controlled object is increased by the design of the compensator parameters,thereby providing vibration suppression for the flexible attachment during and after the attitude maneuvering;the latter Is a pre-feedback control technique that can be used to suppress the residual vibration of the flexible structure.Two kinds of methods are simulated and verified respectively in MATLAB.It is feasible and effective to obtain two kinds of vibration suppression strategies.However,the former stability and coordination to be improved,while the latter has a delay.Finally,based on the finite time control algorithm,Gaussian pseudospectral method and fixed time control method are used to control the maneuverability of the flexible spacecraft in the maneuvering process.The former is the open-loop planning of the whole process of attitude maneuver,and the fast maneuvering problem of spacecraft is transformed into the time optimal problem to solve.The latter uses a fixed-time control algorithm to rapidly converge the attitude to the equilibrium point in an estimated time while suppressing the vibration of the attachment.Simulation results show that the Gaussian pseudospectral method can make the system converge in finite time,but the accuracy is limited and it is sensitive to the initial value of the open-loop programming.As a fixed-time control of closed-loop control,the control method can estimate the convergence time of the system independently of the initial state of the system,and has high convergence speed,high precision and strong robustness.