Research On Attitude Control System With Solar Arrays Spacecraft Via Extended Disturbance Observer Based Controller

With the deepening of research on space technology and the increasing complexity of space mission,more and more spacecraft have begun to use large flexible structures.Due to the flexible and low stiffness characteristics of the flexible attachment,vibration is generated,which affects the stability of the star body and the accuracy of the posture.This paper mainly focuses on the attitude maneuvering of single solar array spacecraft and studies the attitude control strategy.First,the dynamic modeling of spacecraft systems with large flexible attachments is studied.On the premise of ignoring the specific form of the actuator structure,the coupling relationship and coupling characteristics between the star body and the flexible attachment are analyzed,and a dynamic model is established based on the Kane equation.Second,an extended disturbance observer is studied.The observer can obtain external disturbances and estimates of their derivatives by only measuring the angular velocity information.From the establishment of the inference model to the design of the extended disturbance observer,the observer is analyzed.The reason why the observation accuracy increases with the increase of the observer order is pointed out.Third,we study the attitude control strategy of flexible spacecraft.This section designs a PD controller based on improved Rodrigues parameters.By combining the PD controller with extended disturbance observer,disturbance compensation is performed on the PD controller using the extended disturbance observer to improve the control performance of the PD controller.Using MATLAB to simulate the control effect of the attitude control strategy for two hypothetical tasks,small-angle maneuver and large-angle maneuver,respectively.It was found that after the extended disturbance observer was added,the control system has significantly improved the control accuracy of the spacecraft attitude,but the accuracy of the model coordinates of the flexible attachment decreases.Finally,for the control strategy where the PD controller plus extended disturbance observer is not ideal for suppressing vibration of the modal coordinates of the flexible attachment,an independent modal space control method is used,assuming that the modal coordinates of the flexible attachment and its first derivative are measurable and the specific form of the actuator is not considered.A PD plus sliding mode vibration active suppressor was introduced to actively suppress the modal coordinates of spacecraft’s flexible accessories.Simulations of small-angle and large-angle maneuvering missions are performed by MATLAB.The results demonstrate the effectiveness of the independent modal space control method for modal vibration suppression of flexible attachments,but the convergence speed will be lengthened.