Research On High Stability Pointing Control Technology Of Optical Remote Sensing Satellite In High Orbit

The payload of an optical remote sensing satellite in high orbit need ultra-quietmechanical environment and thus more stringent attitude pointing accuracy and stability are required for the satellite.For high precision spacecraft,the effect of spacecraft micro vibration on attitude control must be considered because it is difficult to realize high attitude accuracy and stability of the satellite by control algorithms only.In this thesis,the suppression scheme of spacecraft micro vibration and active control technology of the optical axis of payload are mainly researched.In order to attenuate the micro vibration resulting from rotating attitude control actuators,the passive isolation method is applied and the performances of the concentrated vibration isolation and the distributed vibration isolation for the attitude actuators are compared in this work.The simulation result indicates that by using high-stiffness isolators,the concentrated vibration isolation has a similar performance as the distributed vibration isolation in the satellite maneuvering processes.Using the low-stiffness isolators,the concentrated vibration isolation loses stability more easily than the distributed vibration isolation.The concentrated and distributed vibration isolations have similar performances for attitude stabilizing with both the high-stiffness and the low-stiffness isolators.Besides passive isolation method for the attitude control actuators,the double-layer vibration isolation configuration in which vibration isolator is also used to payload is further studied.The integrated dynamics and control model of the satellite containing typical vibration sources and the payload-body vibration isolator is derived and the attitude control simulation of the satellite is implemented.The performances of the passive isolation and passive-active hybrid isolation are compared in attitude control simulation.The results confirm that the performance of passive isolation in low frequency is insufficient,although its structure is simpler.And the passive-active hybrid isolation improves the accuracy and stability of the payload attitude control by two orders of magnitude.In addition to the general vibration isolation methods,the dynamic modeling and control of a novel satellite named separated satellite which is designed as noncontact is considered in this work.The rigid-flexible coupling dynamics model of a separated satellite with flexible cables is derived using Lagrange method.Based on the proposed model,the flexible cableeffect on the vibration isolation performance and pointing control of the satellite is investigated.The simulation result indicates that as the existence of flexible cables the isolation performance at low frequencies is decreased and steady-state error of pointing control is increased significantly.To reduce the impact of flexible cables,the 6-DOF decoupled controller of payload module based Active Disturbance Rejection Control is designed.Based on the high attitude pointing accuracy and stability of the payload module,the optical axis active pointing control of the steering mirror which is a common optical payload is investigated.The coupled dynamic and the control model of the steering mirror and the satellite is established and the PID controller is designed.The performance of the controller is verified by a semi-physical experiment.The experimental result shows that the pointing control error of the steering mirror is only 0.25?rad.The high accuracy pointing control of the optical axis of the steering mirror is thus achieved.