Attitude Maneuver Control Of Flexible Spacecraft With SGCMGs As Actuator

It is well established that,to minimize the mass of spacecraft structure and span the service life of spacecraft,for the complex space missions with high precision,for example earth observation,satellite rendezvous and so on,flexible spacecraft plays a crucial role.At the same time,as the actuator of flexible spacecraft,single gimbaled control moment gyroscopes(SGCMGs)have been widely used for attitude maneuver because of their large output torque,and sound dynamic performance.Based on the rapid attitude maneuver and rapid stabilization requirement for the flexible spacecraft with SGCMGs as actuator,the SGCMG gimbal servo system tracking control methods,SGCMGs steering law design and SGCMGs-based flexible spacecraft attitude controllers are investigated here.The main works and contributions lie in the following:For the SGCMG gimbal servo system with parametric uncertainties,external disturbance and friction nonlinearity,based on the adaptive control,robust control and finite-time control method,to gaurantee the finite-time convergence of the tracking error,a finite-time adaptive robust control law is proposed,which shows good robustness to inertia perturbation and reduce the adverse effects of external disturbance.Furthermore,based on the previous controllers,to deal with the friction nonlinearit,a desired compensation adaptive robust controller is designed and it can minimize the adverse effects caused by the measured signal noise and external disturbance.The effectiveness of the proposed controllers is demonstrated via theoretical analysis and numerical simulation.To avoid the singularity in the SGCMGs and guarantee the precise output torque,based on the singular robust inverse steering law and singular value decomposition method,an improved variable robust coefficient based inverse steering law is put forward,which enables the SGCMGs to avoid singularity and output precise desired torque.To evaluate the output torque performance of the steering law,the quadratic sum of output torque error is defined as a performance index.The simulation results of SGCMGs as well as the flexible spacecraft attitude maneuver show the effectiveness of the proposed steering law.For attitude control issue of flexible spacecraft with SGCMGs as actuator,to reduce the adverse effect of unknown spacecraft inertia,coupling effect and external disturbance,a SGCMGs-based flexible spacecraft adaptive controller is designed,with the SGCMGs dynamics taken into consideration,which shows good robustness to parameter perturbation and restrain the disturbance.Furthermore,to solve the problems caused by the friction nonlinearity of the actuator,a RBF neural network-based attitude adaptive control law is proposed.To further relax this condition in which the upper bound of the disturbance and coupling effect is known,a robust adaptive controller independent of the upper bound of the disturbance is presented.The Lyapunov technique is adopted to analyze and demonstrate the stabilization of the closed-loop systems,with the above three methods.The effectiveness of the methods is also demonstrated via simulations.A finite-time based adaptive robust controller is proposed for the flexible spacecraft,in which the friction nonlinearity,electromagnetic disturbance in the single gimbaled control moment gyroscopes,inertia perturbation and external disturbance exist.The unknown parameters and upper bound of the disturbance are estimated via the adaptive laws and compensated by the controller so that the controller can be designed regardless of the information of the parameters and the adverse effect of external disturbance on the system is reduced.Via the Lyapunov stability theory,it can be proved that the error of the attitude angle and attitude angular velocity can converge to an small neighborhood containing origin.The simulation results of the flexible spacecraft attitude maneuver show that,with the presented controller,the rapid attitude maneuver of the flexible spacecraft with high pointing precision and stability can be fulfilled.